Cellular Physiology and Biochemistry

Aim: to investigate the association between vitamin D receptor polymorphisms and circulating 1,25-Dihydroxyvitamin D (1,25(OH)2D) levels with keloid scar (KS) risk. Methods: A total of 261 patients with KS and 261 normal healthy individuals were enrolled. VDR gene polymorphisms were determined. Circulating 1,25(OH)2D levels were detected. Results: In this study, we investigated the role of four loci of VDR gene polymorphisms in determining the risk of KS in a Chinese cohort. We found that the TaqI C>T polymorphism was closely associated with the KS incidence. Carriers with CC genotype of TaqI had a higher chance of developing KS. Stratification analyses by sex showed that this trend exists only in female subjects but not in male subjects. Furthermore, the TaqI C>T polymorphism affects the circulating 25-Hydroxyvitamin D levels. The CC carriers had a significantly lower mean circulating 1,25(OH)2D level than TT carriers and CT carriers. KS subjects had significantly lower mean serum circulating 1,25(OH)2D level than controls. The receiver operating characteristic curve analysis revealed that the serum circulating 1,25(OH)2D level at the cut-off point of 16.1 ng/ml could discriminate KS subjects from controls. Conclusion: Collectively, these data provide evidence that the vitamin D/VDR pathway plays an important role in the development of KS. The TaqI gene polymorphisms of VDR and circulating 1,25(OH)2D levels may thus be used as potential markers for prediction of KS development.

8-Cyclopentyl-1,3-dipropylxanthine (CPX) is a selective A1-adenosine receptor antagonist which has been reported to activate Cl- efflux at very low concentrations in cells carrying the cystic fibrosis (CF) defect, but not in cells expressing the wild-type form of the CF transmembrane conductance regulator (CFTR). CPX was suggested as a new therapeutic drug for the treatment of CF. In the present study, we examined the effects of CPX on various types of recombinant cells (Xenopus oocytes, Chinese hamster ovary cells, CF tracheal cells) and native non-CF and CF respiratory epithelial cells. CPX did not activate a whole-cell conductance when applied at concentrations ranging from 1 nmol/l to 100 micromol/l in oocytes injected with water or expressing either wild-type CFTR or mutant deltaF508-CFTR. Correspondingly, CPX (10 micromol/l) did not activate whole-cell conductance in non-CF or CF respiratory epithelial cells and Chinese hamster ovary cells expressing either wild-type CFTR or deltaF508-CFTR. Instead, CPX depolarized Vm by inhibition of a K+ conductance in CF respiratory epithelial cells. At 10 micromol/l CPX marginally decreased intracellular pH in respiratory epithelial cells, independent of expression of wild-type CFTR or mutant CFTR. According to these data, CPX-induced 36Cl efflux reported in previous studies cannot be attributed to direct activation of deltaF508-CFTR Cl- conductance and is probably related to the CPX-induced changes in intracellular pH.

MicroRNAs (miRNAs) are identified as crucial gene regulators in response to myocardial infarction (MI). However, the overall relationships between miRNAs and the gene targets which contribute to the cellular phenotypes in MI are not fully elucidated. To make a better understanding towards functional roles of miRNAs in MI, useful information was mined through bioinformatic techniques. MI-related miRNAs were retrieved from publications, and PicTar, TargetScanS, and miRanda programs were used to predict their gene targets. Gene ontology (GO) and pathway analyses of gene targets were applied to uncover functional roles of miRNAs. The miRNA-gene networks were illustrated by Pajek tool. Finally, validation experiments were performed towards two important miRNAs in the networks. Up to 119 MI-related miRNAs were retrieved from publications. GO and pathway analyses for their predicted gene targets demonstrated that these dysregulated miRNAs were enriched in cardiovascular-related phenotypes. Through illustrating miRNA-gene networks, overall relationships between miRNAs and gene targets were detected especially in processes of apoptosis and angiogenesis. Moreover, experimental data supported bioinformatic predictions that miR-106b served as an anti-apoptotic modulator through inhibition of p21 expression and miR-15b displayed anti-angiogenesis activity. The miRNAs played essential roles in pathological processes of MI. Further, miR-106b and miR-15b maybe mediated as robust regulators in apoptosis or angiogenesis following MI, respectively.

In sensory neurons heat is transduced by a subfamily of TRP channels sharing sequence homology with the capsaicin-sensitive vanilloid receptor subtype 1 (TRPV1), but differing in their thermal response thresholds. To identify a neuronal cell line endogenously expressing noxious heat-transducing ion channels, we examined F-11 cells, a hybridoma derived from rat dorsal root ganglia and mouse neuroblastoma. Using RT-PCR, transcripts homologous to TRPV2 and TRPV4, but not to TRPV1 or TRPV3, were found. We isolated a full-length cDNA of 2.4 kb coding for a 757-amino acid protein corresponding to mouse TRPV2, which was further characterized by immunocytochemistry and electrophysiology. Using the whole-cell patch-clamp technique, we observed a heat-evoked increase in outward and inward currents with a threshold of 51.6 +/- 0.2 degrees C. The current-voltage relationship stimulated by a temperature of 52 degrees C was characterized by an outward rectification with a reversal potential close to -10 mV. Heat-evoked currents could be inhibited by ruthenium red. There was no activation by stimulation with capsaicin or 2-aminoethoxydiphenyl borate. Our results indicate that F-11 cells express functional noxious heat-sensitive TRPV2 channels. Thus, we propose that F-11 cells represent a valuable in vitro model to characterize the properties of TRPV2 in a native neuronal environment.

Background: CC chemokine ligand 11 (CCL11) is related to Th2 cells migration via CC chemokine receptor 3 (CCR3). Th2 cells are involved in the etiology of periodontal disease. However, how the infiltration of Th2 cells is controlled in periodontally diseased tissues is unknown. (-)-Epigallocatechin gallate (EGCG), the major catechin in green tea, has multiple beneficial effects, but the effects of EGCG on CCL11 production are uncertain. In this study, we investigated whether cytokines could induce CCL11 production in human gingival fibroblasts (HGFs). Moreover, we examined the effects of EGCG on CCL11 production in HGFs. Methods and results: ELISA analysis disclosed that interleukin (IL)-4 synergistically enhanced CCL11 production in IL-1β or tumor necrosis factor (TNF)-α-stimulated HGFs. EGCG prevented IL-1β/ IL-4 or TNF-α/IL-4-mediated CCL11 production in a concentration dependent manner. CCL11 production in HGFs was positively regulated by p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK), and c-Jun N terminal kinase (JNK). Western blot analysis revealed that EGCG treatment prevented IL-1β/IL-4 or TNF-α/IL-4-induced ERK and JNK activation in HGFs. Conclusions: These data provide that CCL11 production in HGFs could be associated with Th2 cells infiltration in periodontal lesions. Moreover, EGCG is useful for periodontitis treatment to inhibit CCL11 production.

The preclinical compounds Bay 11-7082 and parthenolide trigger apoptosis, an effect contributing to their antiinflammatory action. The substances interfere with the activation and nuclear translocation of nuclear factor NFκB, by inhibiting NFκB directly (parthenolide) or by interfering with the inactivation of the NFκB inhibitory protein IκB-α (Bay 11-7082). Beyond that, the substances may be effective in part by nongenomic effects. Similar to apoptosis of nucleated cells, erythrocytes may undergo apoptosis-like cell death (eryptosis) characterized by cell membrane scrambling with phosphatidylserine exposure, and cell shrinkage. Thus, erythrocytes allow the study of nongenomic mechanisms contributing to suicidal cell death, e.g. Ca(2+) leakage or glutathione depletion. The present study utilized Western blotting to search for NFκB and IκB-α expression in erythrocytes, FACS analysis to determine cytosolic Ca(2+) (Fluo3 fluorescence), phosphatidylserine exposure (annexin V binding), and cell volume (forward scatter), as well as an enzymatic method to determine glutathione levels. As a result, both NFκB and IκB-α are expressed in erythrocytes. Targeting the NFκB pathway by Bay 11-7082 (IC(50) ≈ 10 μM) and parthenolide (IC(50) ≈ 30 μM) triggered suicidal erythrocyte death as shown by annexin V binding and decrease of forward scatter. Bay 11-7082 treatment further increased intracellular Ca(2+) and led to depletion of reduced glutathione. The effects of Bay 11-7082 and parthenolide on annexin V binding could be fully reversed by the antioxidant N-acetylcysteine. In conclusion, the pharmacological inhibitors of NFκB, Bay 11-7082 and parthenolide, interfere with the survival of erythrocytes involving mechanisms other than disruption of NFκB-dependent gene expression.

K(+)-channels fulfill several important functions in the mammalian kidney such as volume regulation, recirculation and secretion of K(+) ions, and maintaining the resting potential. In this study we used immunocytochemical methods, in situ hybridization, and nephron segment-specific RT-PCR to obtain a detailed picture of the cellular localization of two tandem pore domain potassium (K(2P)) channels, THIK-1 (K(2P)13.1, KCNK13) and THIK-2 (K(2P)12.1, KCNK12). Monospecific antibodies against C-terminal domains of rat THIK-1 and THIK-2 proteins (GST-fusion proteins) were raised in rabbits, freed from cross-reactivity, and affinity purified. All antibodies were validated by Western blot analysis, competitive ELISA, and preabsorption experiments. The expression of THIK channels in specific nephron segments was confirmed by double staining with marker proteins. Results indicate that in rat and mouse THIK-1 and THIK-2 were expressed in the proximal tubule (PT), thick ascending limb (TAL), connecting tubule (CNT), and cortical collecting duct (CCD). In human kidney THIK-1 and THIK-2 were localized in PT, TAL and CCD. Immunostaining of rat tissue revealed an intracellular expression of THIK-1 and THIK-2 throughout the identified nephron segments. However in mouse kidney THIK-2 was identified in basolateral membranes. Overall, the glomerulus, thin limbs and medullary collecting ducts were devoid of THIK-1 and THIK-2 signal. In summary, THIK-1 and THIK-2 are abundantly expressed in the proximal and distal nephron of the mammalian kidney.

Background & Aims: MicroRNAs (miRNAs) have been shown to play essential roles in HSCs activation which contributes to hepatic fibrosis. Our previous miRNA microarray results suggested that miR-126 might be decreased during HSCs activation as other studies. The aim of this study is to investigate the role of miR-126 during HSCs activation. Methods: In this study, the expression of miR-126 during HSCs activation was measured and confirmed by qRT-PCR. Then, miR-126 expression was restored by transfection of lentivirus vector encoding miR-126. Futhermore, cell proliferation was assayed by the cell counting kit-8 (CCK-8), cell migration was assayed by transwell assay, and the markers of activation of HSCs, α-SMA and collagen type I, were assayed by qRT-PCR, Western Blotting, Immunostaining and ELISA. Luciferase reporter assay was used to find the target of miR-126, and Western Blotting and Immunostaining was used to validate the target of miR-126. Then, the expression and the role of the target of miR-126 during HSCs activation was further assessed. Results: The expression of miR-126 was confirmed to be significantly decreased during HSCs activation. Overexpression of miR-126 significantly inhibited HSCs migration but did not affect HSCs proliferation. The expression of α-SMA and collagen type I were both obviously decreased by miR-126 restoration. CRK was found to be the target of miR-126 and overexpression of miR-126 significantly inhibited CRK expression. And it was found that overexpression of CRK also significantly decreased miR-126 expression and promoted HSCs activation. Conclusions: Our study showed that overexpression of miR-126 significantly inhibited the activation and migration of HSCs through targeting CRK which can also decrease miR-126 expression and promote HSCs activation. © 2014 S. Karger AG, Basel.

Murine leukotriene B(4) (LTB(4)) receptor (mBLT1) cDNA was identified by searching the EST database using human LTB(4) receptor as the query sequence. Expression of functional mBLT1 after injection of in vitro transcribed cRNA into Xenopus laevis oocytes was demonstrated as LTB(4)-evoked, Ca(2+)-activated Cl(-) currents recorded by two-electrode voltage clamp. From mBLT1-expressing oocytes, a dose-dependent relationship between the Ca(2+)-activated Cl(-) current and LTB(4) concentration was demonstrated with an apparent EC(50) of 6.7 nM. Following LTB(4) stimulation of mBLT1, we observed two transient, spatially distinct Ca(2+)-activated, inwardly directed Cl(-) currents in the oocytes: a fast peak current requiring relatively high LTB(4) concentrations, and a slowly progressing Cl(-) current. Nucleotides, PGE(2), 12R-hydroxy-5, 8, 14-cis-10-trans-eicosatetraenoic acid, and LTD(4) did not activate mBLT1. U75302, specifically targeting BLT1, significantly reduced LTB(4)-evoked Cl(-) currents. Repetitive LTB(4) administration desensitized the LTB(4)-evoked currents. Activation of protein kinase C (PKC) by PMA addition completely eliminated the LTB(4)-evoked currents, whereas down-regulation of PKC by prolonged PMA exposure (20 h) impaired mBLT1 desensitisation. In addition, Ser-127-Ala substitution of the PKC consensus phosphorylation site on the second intracellular loop prevented the mBLT1 desensitisation. These data indicate that PKC-mediated phosphorylation at Ser-127 leads to mBLT1 desensitisation.

To characterize the effects of long-term β-adrenergic receptor stimulation on Rem protein and mRNA expression in rat heart and possible involvement of miR-132. Adult rats were treated with isoproterenol (ISO, 150 µg.kg.h(-1)) for 2 d and Rem, miR-132, and α1c (the principal subunit of Cav1.2 channels) were measured at protein and mRNA levels with western blot and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) experiments, respectively. Ca(2+) currents and intracellular Ca(2+) signals were evaluated in isolated cardiomyocytes. Systemic administration of ISO led to decreases in Rem protein and mRNA levels (down to 49%). Furthermore, levels of the microRNAs (miRs) miR-132 and miR-214 were upregulated 5- and 9-fold, respectively. Transfection of miR-132, but not miR-214, into HEK293 cells reduced the expression of a luciferase reporter gene controlled by a conserved 3´-untranslated region (UTR) of Rem by half. Chronic ISO administration also led to a 25% decrease in the amplitude of peak L-type Ca(2+) currents, a 40% decrease in α1c subunit protein abundance at the membrane level, and a 60% decrease in expression of α1c channel subunit mRNA. These results suggest that Rem expression is down-regulated posttranscriptionally by miR-132 in response to long-term activation of β-adrenergic signaling, but this down-regulation does not produce a larger Ca(2+) influx through Cav1.2 channels. © 2015 S. Karger AG, Basel.

Tanshinone IIA is a lipid-soluble pharmacologically active compound extracted from the rhizome of Chinese herb Salvia miltiorrhiza, a well-known traditional Chinese medicine used for the treatment of cardiovascular disorders. Previous studies have identified that tanshinone IIA inhibited overexpression of miR-1 in hypoxic neonatal cardiomyocytes. This study was designed to examine the effects of tanshinone IIA on miR-133 expression under hypoxic condition. Neonatal rat cardiomyocytes were cultured in a hypoxic environment (2% O(2)+93% N(2)+5% CO(2)) at 37°C for 24 hours. MTT, TUNEL assays, and Flow Cytometry (FCM) were performed to identify cell apoptosis. Western blot was used to examine the expression of ERK1/2 and miR-133 level was quantified by Real-time PCR. Our results showed that apoptosis was induced by hypoxia. Typical apoptotic cells were seen by TUNEL assay, and FCM showed an apoptosis rate of 13.32% in hypoxic group. Apoptosis rate in hypoxic cells was reduced significantly by tanshinone IIA. In addition, the expression level of miR-133 was increased in hypoxic cells and further upregulated by tanshinone IIA. The stress-activated protein kinase MAPK ERK1/2 was activated by hypoxia and further increased with tanshinone IIA treatment. The present study demonstrated that tanshinone IIA enhanced cell resistance to hypoxic insult by upregulating miR-133 expression through activating MAPK ERK1/2 in neonatal cardiomyocytes.

MicroRNA-133b (miR-133b) has been shown to play a critical role in spinal cord regeneration. The aim of this study was to investigate the cellular role of miR-133b in neural cells. PC12 cells and primary cortical neurons (PCNs) were transfected with lenti-miR-133b, lenti-miR-133b inhibitor, plasmid-shRNA-RhoA, plasmid-RhoA and their negative controls. After 48 hours of transfection, the levels of proteins and mRNA or miRNA were evaluated by Western blotting and qRT-PCR, respectively. Moreover, the neurite outgrowth was analyzed by Image J. For pharmacological experiments, inhibitors of MEK1/2 kinase (PD98059), phosphoinositide-3 kinase (PI3K) (LY294002) and ROCK (Y27632) were added into the culture medium. Overexpression of miR-133b in PC12 cells enhanced neurite outgrowth. Conversely, inhibition of miR-133b reduced neurite length. We further identified RhoA as a target and mediator of mir-133b for neurite extension by Western blot and knockdown experiment. Moreover, overexpression of RhoA could attenuate the neurite growth effects of miR-133b. Also, we observed that miR-133b activated MEK/ERK and PI3K/Akt signaling pathway by targeting RhoA. Finally, in PCNs, miR-133b also increased axon growth and attenuated axon growth restrictions from chondroitin sulfate proteoglycans (CSPG). In summary, our study suggested that miR-133b regulated neurite outgrowth via ERK1/2 and PI3K/Akt signaling pathway by RhoA suppression. © 2015 S. Karger AG, Basel.

Background/Aims: Demonstrating the molecular mechanisms of human adipose tissue-derived mesenchymal stem cells (hADSCs) differentiation and proliferation could develop hADSCs-based cell therapy. Methods: The microRNA-137 (miR-137) and cell division control protein 42 homolog (CDC42) levels were regulated by oligonucleotides transfection. The adipogenic differentiation was induced for 10 days in an adipogenic medium and assessed by using an Oil Red O stain. The regulation of miR-137 on CDC42 expression was determined by western blot, real-time PCR and luciferase reporter assay. Results: We confirmed the roles of miR-137 on hADSCs proliferation and adipogenic differentiation. We showed that overexpression of miR-137 inhibited both hADSCs proliferation and adipogenic differentiation. Overexpression of miR-137 also downregulated protein and mRNA levels of CDC42, a predicted target of miR-137. In contrast, inhibition of miR-137 with 2'-O-methyl antisense RNA increased proliferation and adipogenic differentiation in hADSCs. Luciferase reporter activity in the miR-137 target site within the CDC42 3'UTR was lower in miR-137-transfected hADSCs than in control miRNA-transfected hADSCs. RNA interference-mediated downregulation of CDC42 in hADSCs inhibited their proliferation and adipogenic differentiation. Conclusion: Our results indicate that miR-137 regulates hADSCs adipogenic differentiation and proliferation by directly targeting CDC42. These findings improve our knowledge of the molecular mechanisms governing hADSCs differentiation and proliferation. © 2014 S. Karger AG, Basel.

Excessive endoplasmic reticulum stress (ERS) triggers apoptosis in various conditions including diabetic cardiomyopathy and pressure overload-induced cardiac hypertrophy and heart failure. The primary function of 14-3-3 protein is to inhibit apoptosis, but the roles of this protein in protecting against cardiac ERS and apoptosis are largely unknown. We investigated the roles of 14-3-3 protein in vivo during cardiac ERS and apoptosis induced by pressure overload or thapsigargin injection using transgenic (TG) mice that showed cardiac-specific expression of dominant negative (DN) 14-3-3eta. Cardiac positive apoptotic cells and the expression of glucose-regulated protein (GRP)78, inositol-requiring enzyme (Ire)1alpha, tumor necrosis factor receptor (TNFR)-associated factor (TRAF)2, CCAAT/enhancer binding protein homology protein (CHOP), caspase-12, and cleaved caspase-12 protein were significantly increased in the pressure-overload induced DN 14-3-3eta mice compared with that in the WT mice. Furthermore, thapsigargin injection significantly increased the expression of GRP78 and TRAF2 expression in DN 14-3-3eta mice compared with that in the WT mice. The enhancement of 14-3-3 protein may provide a novel protective therapy against cardiac ERS and ERS-initiated apoptosis, at least in part, through the regulation of CHOP and caspase-12 via the Ire1alpha/TRAF2 pathway.

Diabetic cardiomyopathy is associated with increased oxidative stress and inflammation. Mammalian 14-3-3 proteins are dimeric phosphoserine-binding proteins that participate in signal transduction and regulate several aspects of cellular biochemistry. The aim of the study presented here was to clarify the role of 14-3-3 protein in the mitogen activated protein kinase (MAPK) and nuclear factor-kB (NF-κB) signaling pathway after experimental diabetes by using transgenic mice with cardiac-specific expression of a dominant-negative 14-3-3 protein mutant (DN 14-3-3). Significant p-p38 MAPK activation in DN 14-3-3 mice compared to wild type mice (WT) after diabetes induction and with a corresponding up regulation of its downstream effectors, p-MAPK activated protein kinase 2 (MAPKAPK-2). Marked increases in cardiac hypertrophy, fibrosis and inflammation were observed with a corresponding up-regulation of atrial natriuretic peptide, osteopontin, connective tissue growth factor, tumor necrosis factor α, interleukin (IL)-1β, IL-6 and cellular adhesion molecules. Moreover, reactive oxygen species, left ventricular expression of NADPH oxidase subunits, p22 phox, p67 phox, and Nox4, and lipid peroxidation levels were significantly increased in diabetic DN 14-3-3mice compared to diabetic WT mice. Furthermore, myocardial NF-κB activation, inhibitor of kappa B-α degradation and mRNA expression of proinflammatory cytokines were significantly increased in DN 14-3-3 mice compared to WT mice after diabetes induction. In conclusion, our data suggests that depletion of 14-3-3 protein induces cardiac oxidative stress, inflammation and remodeling after experimental diabetes induction mediated through p38 MAPK, MAPKAPK-2 and NF-κB signaling.

Somatostatin-14 (SRIF-14), a neuropeptide co-stored with acetylcholine in the cardiac parasympathetic innervation, exerts both positive and negative influences directly on contraction of ventricular cardiomyocytes, indicative of involvement of more than one of five known SRIF (SSTR) receptor subtypes. The aim was to characterize receptor subtype expression in adult rat ventricular cardiomyocytes and to investigate the influence of a series of SRIF (SSTR) subtype-selective agonists on contractile parameters. mRNA and protein expression of each receptor subtype were quantified by RT-PCR and immunoblotting respectively; for contraction studies, cells were stimulated at 0.5 Hz under basal conditions and in the presence of isoprenaline (ISO, 10(-8)M). all five SRIF (SSTR) receptor subtypes were expressed in cardiomyocytes although SRIF1A (SSTR2) and SRIF2A (SSTR1) were less abundant than the other subtypes. L803087 (10(-8)M), a SRIF2B (SSTR4) agonist, attenuated ISO-stimulated peak contractile amplitude and prolonged relaxation time (T(50)). L796778 (10(-7)M), a SRIF1C (SSTR3) agonist, augmented basal and ISO-stimulated peak contractile amplitude; L779976 (10(-8)M) and L817818 (10(-9)M), agonists at SRIF1A (SSTR2) and SRIF1B (SSTR5) receptors, respectively, also augmented ISO-stimulated peak amplitude. These data support involvement of SRIF2B (SSTR4) receptors in the negative contractile effects of SRIF-14, while one or more of the three SRIF1 receptor subtypes (SSTR2, 3 or 5) may contribute to the positive contractile effects of SRIF-14.

The present study aimed at elucidating the mechanism(s) of serotonin (5-HT) efflux induced by thapsigargin from human platelets in the absence of extra-cellular Ca2+. Efflux of pre-loaded radiolabeled serotonin was generally determined by filtration techniques. Cytosolic concentrations of Ca2+, Na+ and H+ were measured with appropriate fluorescent probes. 5-HT efflux from control or reserpine-treated platelets--where reserpine prevents 5-HT transport into the dense granules--was proportional to thapsigargin evoked cytosolic [Ca2+]c increase. Accordingly factors as prostacyclin, aspirin and calyculin which reduced [Ca2+]c-increase also inhibited the 5-HT efflux. Thapsigargin, which also caused a remarkable increase in cytosolic [Na+]c, promoted less 5-HT release, in parallel to lower [Na+]c and [Ca2+]c increase, when added to platelet suspensions containing low [Na+]. The Na+/H+ exchanger monensin increased the [Na+]c and induced 5-HT efflux without affecting the Ca2+ level. The 5-HT efflux induced by both [Ca2+] or [Na+]c increase did not depend on pH or membrane potential changes, whereas it decreased in the absence of extra-cellular K+, and increased in the absence of Cl- or Na+. Increases in [Ca2+]c and [Na+]c independently induce serotonin efflux through the outward directed plasma membrane serotonin transporter SERT. This event might be physiologically important at the level of capillaries or narrowed arteries where platelets are subjected to high shear stress which causes [Ca2+]c increase followed by 5-HT release which might exert vasodilatation.

Background/aims: MicroRNAs (miRNAs) are reported to regulate cell invasion and functions by interfering with the translation of target mRNAs, but the role of miRNAs in esophageal cancer (EC) remains unclear. Methods: RT-PCR and Western blot were used to detect the expression of miRNAs and candidate genes in EC samples (n=89). miR-140 mimics and inhibitor were tansfected in human TE-1 and Eca-109 cells. The transwell assay was used to examine the cell invasive ability. The regulation mechanism was confirmed by luciferase reporter assay. The markers of EMT were detected by using Western blot. Results: miR-140 expression was decreased in the EC tissues compared with the corresponding adjacent tumor tissues. Low expression of miR-140 promotes cell invasion by using transwell assay, while the effect of miR-140 high expression is reverse. Slug, a target gene of miR-140, was examined by luciferase assay and Western blot. Conclusions: miR-140 may regulate the cell invasion of EC via controlling Slug expression.

Background/Aims: Mounting evidence has shown that aberrant expression of miRNAs correlates with human cancers, and that miRNAs can function as tumor suppressors or oncogenes. Here, we investigated the role and mechanism of miR-142-3p in human osteosarcoma. Methods: We used quantitative real-time RT-PCR to measure the expression of miR-142-3p in human osteosarcoma cell lines and tissues. The roles of miR-142-3p in osteosarcoma development were studied using cultured HOS, MG63 and Saos-2 cells and tumor xenograft analyses in nude mice; their target genes were also investigated. Results: We found that miR-142-3p was significantly downregulated in osteosarcoma cell lines and clinical specimens. Overexpression of miR-142-3p suppressed osteosarcoma cell proliferation, migration and invasion, whereas miR-142-3p knockdown increased these parameters. The xenograft mouse model also revealed the suppressive effect of miR-142-3p on tumor growth. High mobility group AT-hook 1 (HMGA1) was identified as a target of miR-142-3p. Downregulation of HMGA1 induced effects on osteosarcoma cell lines similar to those induced by miR-142-3p. In contrast, restoration of HMGA1 abrogated the effects induced by miR-142-3p up-regulation. Conclusion: These results indicated that miR-142-3p may function as a tumor suppressor by targeting HMGA1 in osteosarcoma. © 2014 S. Karger AG, Basel.

MiRNAs are noncoding RNAs of 20-24 nucleotides that function as post-transcriptional negative regulators of gene expression. MiRNA genes are usually transcribed by RNA polymerase II in the nucleus. Their initial products are pre-miRNAs which have cap sequences and polyA tails. The p53-induced glycolysis and apoptosis regulator (TIGAR) was discovered through microarray analysis of gene expression following activation of p53. However, little is known about the effect of miR-144 on cell proliferation and apoptosis and how it interacts with TIGAR. We performed real-time PCR, western blotting, CCK8, colony formation, tumor growth, flow cytometry, Caspase3/7 activity, Hoechst 33342 staining, MDC staining of autophagic cells and luciferase reporter assays to detect the influence of miR-144 to lung cancer cells. miR-144 targeted TIGAR, inhibited proliferation, enhanced apoptosis, and increased autophagy in A549 and H460 cells. Our study improves our understanding of the mechanisms underlying lung cancer pathogenesis and may promote the development of novel targeted therapies. © 2015 S. Karger AG, Basel.

miR-146a polymorphisms have been involved in susceptibility to multiple diseases. The aim of the present study was to analyze the potential association between two functional miR-146a polymorphisms (rs2910164 and rs57095329) and multiple sclerosis (MS) in the Han Chinese population. A cohort of 525 patients and 568 healthy controls were genotyped to detect the two polymorphisms by SNaPshot. No significant differences were detected in the distribution of the two miR-146a polymorphisms between the patients and controls (P > 0.05). However, stratification by gender showed a statistically significant difference in the frequency of the genotype rs2910164 between MS patients and control females (P=0.009). Further stratification analysis by subgroup revealed that the miR-146a rs2910164 C allele conferred a higher risk of developing relapsing-remitting MS (RRMS) (P=0.018). In addition, the rs2910164 C allele was significantly associated with increased expression of miR-146a in patients with RRMS (P=0.025). Moreover, patients with the rs2910164 C allele released more TNF-α and IFN-γ, but not IL-1β, compared with individuals carrying the homozygous GG genotype (P < 0.05). Our results provide evidence that rs2910164 may play a role in MS susceptibility in females. The rs2910164 G>C variation may affect the expression of miR-146a and the release of proinflammatory cytokines. © 2015 S. Karger AG, Basel.

Tyrosine phosphorylation depends on the activity of receptor and non-receptor tyrosine kinases and promote cell growth, differentiation and apoptosis. Different stressors are known to stimulate tyrosine kinase activities and this could explain a wide spectrum of effects that these agents produce on different organisms. We studied the effects of heavy metals and pro-oxidants on tyrosine kinase signalling in trout hepatoma cells (RTH 149) by Western immunoblotting. Use of antiphosphotyrosine showed that Hg(2+) and Cu(2+)in the microM range, and H(2)O(2) in the mM range, induced tyrosine phosphorylation. The effect of Cu(2+)was prevented by pre-incubation with genistein, while those of Hg(2+)and H(2)O(2) were only decreased, probably due to tyrosine kinase stimulation coupled to phosphatase inhibition. Phosphospecific antibodies against the three types of MAPKs showed that ERK is activated by heavy metals only, while p38 and SAPK/JNK are activated by H(2)O(2), Hg(2+), and Cu(2+) plus low H(2)O(2). Cell pre-incubation with p38 inhibitors indicated that ERK activation by H(2)O(2) is prevented by concomitant activation of p38. Phosphospecific STAT antibodies revealed activation by H(2)O(2) only. In conclusion, fish cell exposure to heavy metals and pro-oxidants produce specific tyrosine kinase responses, involving cross talk and redox modulatory effects.

Cultured renal proximal tubule cells dedifferentiate from an oxidative metabolism to high rates of glycolysis over time. There are many reasons why cells in culture dedifferentiate, not least being a lack of homogenous nutrient supply and poor oxygenation. To this end we have developed a new cell culture device (EpiFlow), which combines continuous perfusion of medium with continuous oxygenation of cells grown on microporous supports. LLC-PK(1) cells cultured under EpiFlow conditions were compared with the same cells grown under conventional static conditions. EpiFlow maintained cells exhibited an improved oxidative metabolism as evidenced by 1) a decreased activity of glycolytic enzymes, 2) an increase in the activity of mitochondrial phosphate-dependent-glutaminase, 3) an increase in cellular ATP content, and 4) an improved morphology (increased cell height, mitochondrial density and an increased number and height of microvilli). In addition, LLC-PK(1) cells maintained under perfusion conditions exhibited an increased sensitivity to the respiratory chain blocker antimycin A as assayed by mitochondrial membrane potential (JC-1). We conclude that LLC-PK(1) cells maintained under EpiFlow conditions develop an improved oxidative metabolism that is more comparable to the in vivo situation.

In rheumatoid arthritis (RA), synovial fibroblast-like cells (SF) contribute significantly to articular inflammation. They express distinct patterns of genes associated with cell proliferation and differentiation and elevated levels of cytokines and chemoattractant factors, including IL-16. Here we investigated pathways regulating IL-16 expression in fibroblasts from RA patients in comparison to fibroblasts from osteoarthritis (OA) patients. Fibroblasts were isolated from dermal and articular biopsies, expanded and pathways of IL-16 induction were investigated by real time quantitative RT/PCR, immuno blot and ELISA. Stimulation of cAMP dependent signal transduction by forskolin induced prominent IL-16 RT/PCR signals in OA-DF and OA-SF. In contrast, in RA-DF and RA-SF staurosporine significantly augmented IL-16 RT/PCR signals, but forskolin induced less IL-16 transcript amounts. Activation of protein kinase C by PMA induced a significant IL-16 response only in RA-SF. Addition of IL-1beta or TNF-alpha did not upregulate IL-16 mRNA but secretion of the mature IL-16 cytokine was activated in serum starved cells in presence of IL-1beta. Our results suggest that RA fibroblasts differ from OA fibroblasts with respect to their sensitivities to kinase/phospatase signal transduction pathways. The enhanced expression of IL-16 in the synovial membrane early in RA vs OA may be associated in part with these distinct signaling responses.

The weak inward rectifier potassium channel ROMK is important for water and salt reabsorption in the kidney. Here we identified Golgin-160 as a novel interacting partner of the ROMK channel. By using yeast two-hybrid assays and co-immunoprecipitations from transfected cells, we demonstrate that Golgin-160 associates with the ROMK C-terminus. Immunofluorescence microscopy confirmed that both proteins are co-localized in the Golgi region. The interaction was further confirmed by the enhancement of ROMK currents by the co-expressed Golgin-160 in Xenopus oocytes. The increase in ROMK current amplitude was due to an increase in cell surface density of ROMK protein. Golgin-160 also stimulated current amplitudes of the related Kir2.1, and of voltage-gated Kv1.5 and Kv4.3 channels, but not the current amplitude of co-expressed HERG channel. These results demonstrate that the Golgi-associated Golgin-160 recognizes the cytoplasmic C-terminus of ROMK, thereby facilitating the transport of ROMK to the cell surface. However, the stimulatory effect on the activity of more distantly-related potassium channels suggests a more general role of Golgin-160 in the trafficking of plasma membrane proteins.

To elucidate the influence and mode of action of HMR1726 (the active metabolite of leflunomide) on TNF-alpha and IL-17 activated metalloproteinases expression in synoviocytes. Synovial fibroblasts from RA and OA patients were stimulated with both cytokines and altered gene expression in the presence or absence of leflunomide was detected by microarray analyses and quantitative RT-PCR. Protein expression was detected by western blotting and commercial ELISAs. Microarray analyses revealed that the addition of HMR1726 (50 microM) to TNF-alpha and IL-17- stimulated synoviocytes induced gene expression of metallo-proteinases, especially MMP-1 and -3 in comparison to activated synoviocytes in the absence of leflunomide. To confirm these data, we examined the influence of different concentrations of HMR1726 in synoviocytes from further 5 OA and 7 RA patients by quantitative PCR. HMR1726 gradually induced MMP-1 and MMP-3 gene expression in a dose-dosedependent manner. Similar results were observed on protein levels. Examination of signal transduction pathways participating in the regulation of leflunomideinduced MMPs expression showed that the mechanism underlying activation of MMP-1 is in part p38- and activation of MMP-3 was MEK1/2- dependent. Leflunomide was not able to abolish expression of metallo-proteinases in synoviocytes activated with TNF-a and IL-17.

CC chemokine ligand 20 (CCL20) plays a pivotal role in the recruitment of Th17 cells and thus in the development of periodontal disease. Epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), the major catechins in green tea, have multiple beneficial effects, but the effects of catechins on CCL20 production in human gingival fibroblasts (HGFs) are not known. In this study, we investigated the mechanisms by which EGCG and ECG inhibit interleukin (IL)-17A-induced CCL20 production in human gingival fibroblasts. IL-17A increased CCL20 production in HGFs in a concentration-dependent manner. EGCG and ECG prevented IL-17A-mediated CCL20 production in HGFs. Inhibitors of p38 mitogen-activated protein kinase (MAPK) or extracellular signal-regulated kinase (ERK) decreased IL-17A-induced CCL20 production. EGCG and ECG prevented IL-17A-induced phosphorylation of p38 MAPK and ERK in HGFs. In addition, EGCG and ECG attenuated IL-17 receptor expression on HGFs. These data provide a novel mechanism through which the green tea flavonoids catechins could be used to provide direct benefits in periodontal disease.

Background: Interleukin (IL)-17A, a newly identified cytokine, may participate in the transition of a stable plaque into an unstable plaque. Macrophages play a critical role in the destabilization of atherosclerotic plaque . Methods: RAW 264.7 cells were stimulated with IL-17A. The mRNA expression of inflammatory cytokines was determined by RT-PCR. The cytokines production in the supernatants was measured by ELISA. Small interfering RNA (siRNA) was used to confirm that IL-17A-induced pro-inflammatory cytokines production via IL-17RA signaling. The western blot assay was used to detect the phosphorylation of MAPKinases including p38 and ERK1/2. The DNA binding activity of nuclear factor NF-κB and AP-1 were detected by EMSA. Results: IL-17A induced the production of pro-inflammatory cytokines in macrophages in a time- and dose-dependent manner, such as tumor necrosis factor (TNF)-α, IL-1β, and IL-6. Meanwhile, IL-17A resulted in the phosphorylation of p38 and ERK1/2 and increased DNA-binding activity of NF-κB and AP-1. Pharmacological inhibitors of p38 and ERK1/2 partly attenuated IL-17A-induced TNF-α, IL-1β, and IL-6 production. Either NF-κB inhibitor or AP-1 inhibitor also partly decreased the IL-17A-induced cytokine production. Conclusions: IL-17A induces pro-inflammatory cytokines production in macrophages via MAPKinases, NF-κB and AP-1 pathway. © 2013 S. Karger AG, Basel.

17β-estradiol (E2) is a risk factor for the development of breast cancer, and cause tumorigenesis in epithelial breast cells. Moreover, E2 has distinct effects on different tissues that are attributed to the presence of two estrogen receptor isoforms, ERα and ERβ. The effect of E2 on mitochondrial biogenesis and function was investigated in two breast cancer cell lines with different estrogen receptor ratios, MCF-7 (high ERα/ERβ ratio) and T47D (low ERα/ERβ ratio) cell lines treated with physiological concentrations of E2 (1 nM). Mitochondria of the MCF-7 cell line showed an increase in proliferation but a decrease in functionality, while the T47D cell line, with low ERα/ERβ ratio, maintained functionality with fewer mitochondria. Our results suggest that ERs endowment and its subtypes relation have an effect on treatment response and could contribute new ideas about mitochondria and ERs in breast cancer, as well as new indicators to the disease progression.

17β-estradiol (17βE2) plays an important cardiovascular role by activating estrogen receptors (ER) α and ERβ. Previous studies demonstrated that the novel estrogen G protein-coupled receptor (GPR30/GPER) mediates estrogen action in different tissues. We have recently shown in the rat heart that 17βE2 elicits negative inotropism through ERα, ERβ and GPR30, by triggering activation of ERK1/2, phosphatidylinositol 3-kinase (PI3K), protein kinase A (PKA) and endothelial Nitric Oxide synthase (eNOS) signaling. In the present study, using the isolated and Langendorff-perfused rat heart as a model system we analyzed: i) whether and to which extent 17βE2 modifies mammalian ventricular myocardial relaxation (lusitropism); ii) the type of ERs and the signaling pathways involved in this effect. We found that 17βE2 negatively modulated the ventricular lusitropic performance. This effect, which partially involved the vascular endothelium, recruited ERβ and occurred via PI3K, eNOS-NO-cGMP-protein kinase G (PKG) transduction cascade. Of note, 17βE2-mediated negative lusitropism associated with a modification of phospholamban (PLN) phosphorylation and S-nitrosylation (SNO) both in isolated Langendorff rat heart and in isolated cardiomyocytes. Taken together, our results allow including 17βE2 to the family of substances that control ventricular relaxation. This is of relevance in relation not only to the normal endocrine control of cardiac function, but also to physio-pathologic conditions characterized by an altered ventricular diastolic performance.

BMS-191095 is an opener of the mitochondrial ATP-regulated potassium channel, which has been shown to provide cytoprotection in models of ischemia-reperfusion induced injury in various tissues. This study aimed at checking the protective action of BMS-191095 under the conditions of oxidative stress or disruption of intracellular calcium homeostasis. Methods: The cytoprotective potential of BMS-191095 was tested in C2C12 myoblasts injured by treatment with H(2)O(2) or calcium ionophore A23187. The influence of the opener on intracellular calcium levels, calpain activity and respiration rates were determined. Results: BMS-191095 protected myoblasts from calcium ionophore A23187-induced injury, but not from H H(2)O(2)-induced injury. A23187-mediated cell damage was also prevented by calpain inhibitor PD 150606. A23187 administration led to a transient increase in cytosolic calcium levels, concomitant activation of calpains and a decrease in state 3 respiration rates, indicating mitochondrial dysfunction. Co-administration of BMS-191095 diminished calpain activation in A23187-treated cells but did not prevent mitochondrial damage. In the presence of BMS-191095, restoration of cytosolic calcium concentrations to basal levels after A23187 treatment was considerably faster which may underly the reduced activation of calpains. Conclusion: The BMS-191095-mediated cytoprotection observed in C2C12 myoblasts results probably from modulation of intracellular calcium transients leading to prevention of calpain activation.

Background/aims: Acetylcholine (ACh) is known to modulate the cardiac redox environment and thereby suppress reactive oxygen species (ROS) generation during oxidative stress. However, there is little information about its regulation on ROS clearance. Here we investigate the beneficial effects of ACh on superoxide dismutase (SOD) as key ROS-detoxifying enzyme system in cultured rat cardiomyoblasts. Methods: H9c2 cells were subjected to hypoxia/reoxygenation (H/R) to mimic oxidative stress. Western blot was used to detect the expression of SOD and related signaling molecules. Specific protein knockdown was performed with siRNA transfection. Results: ACh treatment on the beginning of reoxygenation decreased ROS and apoptosis. ACh increased ATP synthesis and mitochondrial DNA. Furthermore, ACh significantly reversed H/R-induced reduction in protein expressions and activities of SOD. ACh stimulated peroxisome proliferator activated receptor γ co-activator 1α (PGC-1α) and decreased forkhead box subfamily O3a (FoxO3a) phosphorylation. Atropine (muscarinic receptor antagonist) abolished the cytoprotection afforded by ACh. PGC-1α siRNA blocked ACh-induced invigorating effects on SOD2, whereas it did not alter SOD1 and FoxO3a phosphorylation. FoxOSa siRNA drastically decreased the expressions of SOD2 and PGC-1α, while it did not affect SOD1. Conclusion: ACh activates SOD2 within mitochondria through FoxO3a/PGC-1α pathway and up-regulates SOD1 in the cytoplasm, thus protecting against oxidative injury induced by H/R. Our findings provide new insights into mechanisms underlying the cardioprotection of ACh on ROS detoxifying.

Pharmacological modification of protein kinase CK1 (casein kinase 1) has previously been shown to influence suicidal erythrocyte death or eryptosis, which is triggered by activation of Cl(-)-sensitive Ca(2+)-permeable cation channels. Ca(2+) entering through those channels stimulates cell membrane scrambling and opens Ca(2+)-activated K(+)-channels resulting in KCl exit and thus cell shrinkage. The specific CK1-inhibitor D4476 (1 µM) blunted, whereas the specific CK1 αactivator pyrvinium pamoate (10 µM) enhanced cell membrane scrambling. The substances were at least partially effective through modification of cytosolic Ca(2+)-activity. The present study explored, whether pyrvinium pamoate indeed influences Cl(-)-sensitive cation-channels in erythrocytes. As a result, removal of Cl(-)increased Fluo3-fluorescence (reflecting cytosolic Ca(2+)-activity), triggered cell membrane scrambling (apparent from annexin-V-binding), and decreased forward scatter (pointing to cell shrinkage). Pyrvinium pamoate significantly augmented the effect of Cl(-)-removal on Fluo3 fluorescence and annexin-V-binding, but blunted the effect on forward scatter. According to whole cell patch clamp recording, Cl(-)removal activated a cation current, which was significantly enhanced by pyrvinium pamoate. Pyrvinium pamoate inhibited Ca(2+)-activated K(+)-channels. Ca(2+)-ionophore ionomycin (1 µM) decreased forward scatter, an effect significantly blunted by pyrvinium pamoate. In conclusion, pyrvinium pamoate activates Cl(-)-sensitive Ca(2+)-permeable cation channels with subsequent Ca(2+)-entry and inhibits Ca(2+)-activated K(+)-channels thus blunting the stimulating effect of Ca(2+) on those channels, K(+)-exit and thus cell shrinkage.

FBI-1, a member of the POK (POZ and Kruppel) family of transcription factors, plays a role in differentiation, oncogenesis, and adipogenesis. eEF1A is a eukaryotic translation elongation factor involved in several cellular processes including embryogenesis, oncogenic transformation, cell proliferation, and cytoskeletal organization. CCS-3, a potential cervical cancer suppressor, is an isoform of eEF1A. We found that eEF1A forms a complex with FBI-1 by co-immunoprecipitation, SDS-PAGE, and MALDI-TOF Mass analysis of the immunoprecipitate. GST fusion protein pull-downs showed that FBI-1 directly interacts with eEF1A and CCS-3 via the zinc finger and POZ-domain of FBI-1. FBI-1 co-localizes with either eEF1A or CCS-3 at the nuclear periplasm. CCS-3 enhances transcriptional repression of the p21CIP1 gene (hereafter referred to as p21) by FBI-1. The POZ-domain of FBI-1 interacts with the co-repressors, SMRT and BCoR. We found that CCS-3 also interacts with the co-repressors independently. The molecular interaction between the co-repressors and CCS-3 at the POZ-domain of FBI-1 appears to enhance FBI-1 mediated transcriptional repression. Our data suggest that CCS-3 may be important in cell differentiation, tumorigenesis, and oncogenesis by interacting with the proto-oncogene FBI-1 and transcriptional co-repressors.

Joint cartilage defects are difficult to treat due to the limited self-repair capacities of cartilage. Cartilage tissue engineering based on stem cells and gene enhancement is a potential alternative for cartilage repair. Bone morphogenetic protein 2 (BMP2) has been shown to induce chondrogenic differentiation in mesenchymal stem cells (MSCs); however, maintaining the phenotypes of MSCs during cartilage repair since differentiation occurs along the endochondral ossification pathway. In this study, hypoxia inducible factor, or (HIF)-1α, was determined to be a regulator of BMP2-induced chondrogenic differentiation, osteogenic differentiation, and endochondral bone formation. BMP2 was used to induce chondrogenic and osteogenic differentiation in stem cells and fetal limb development. After HIF-1α was added to the inducing system, any changes in the differentiation markers were assessed. HIF-1α was found to potentiate BMP2-induced Sox9 and the expression of chondrogenesis by downstream markers, and inhibit Runx2 and the expression of osteogenesis by downstream markers in vitro. In subcutaneous stem cell implantation studies, HIF-1α was shown to potentiate BMP2-induced cartilage formation and inhibit endochondral ossification during ectopic bone/cartilage formation. In the fetal limb culture, HIF-1α and BMP2 synergistically promoted the expansion of the proliferating chondrocyte zone and inhibited chondrocyte hypertrophy and endochondral ossification. The results of this study indicated that, when combined with BMP2, HIF-1α induced MSC differentiation could become a new method of maintaining cartilage phenotypes during cartilage tissue engineering. © 2015 S. Karger AG, Basel.

Background/Aims: Acute kidney injury (AKI) is a major complication of kidney transplantation, resulting in early graft dysfunction. Since diuretic acetazolamide (AZA) has been shown to improve contrast induced AKI, we hypothesized that AZA also protected against ischemia-reperfusion (I/R) caused AKI. Methods: An in vivo mouse renal I/R injury model and an in vitro H2O2 stimulated HK-2 cell injury model were utilized to examine the renoprotective effect of AZA. Renal injury and blood flow were measured. Nitric oxide synthase (eNOS)/Nitric oxide (NO), cell apoptosis and hypoxia-inducible factor-1α (HIF-1α) changes were analyzed. Results: AZA reduced kidney injury scores and improved renal function by decreasing serum creatinine and BUN levels after I/R. Impaired renal blood flow was restored by increasing eNOS activities and NO production, as indicated by Laser Doppler imaging. TUNEL staining presented that AZA reduced apoptotic cells due to attenuated caspase activation and increased Bcl-2/Bax ratio. Furthermore, HIF-1α induction by AZA was demonstrated. AZA also enhanced in vitro NO production, reduced cell apoptosis and increased HIF-1α expression. Knockdown of HIF-1α by RNAi confirmed that AZA exerted its protective role depending on HIF-1α. AZA's effects were significantly reduced by Akt inhibitor LY294002. Conclusions: The present study demonstrated that AZA exerted a renoprotective role against I/R induced AKI through activating HIF-1α and downstream pathways. © 2013 S. Karger AG, Basel.

Background/aims: The mechanisms involved in endothelial barrier dysfunction induced by hypoxia are incompletely understood. There is debate about the role of hypoxia-inducible factor-1α (HIF-1α) in endothelial barrier disruption. The aim of this study was to investigate the effect of genetic overexpression of HIF-1α on barrier function and the underlying mechanisms in hypoxic endothelial cells. Methods: The plasmid pcDNA3.1/V5-His-HIF-1α was stably transfected into human endothelial cells. The cells were exposed to normoxia or hypoxia. The mRNA and protein expressions of HIF-1α were detected by RT-PCR and Western blot respectively. The barrier function was assessed by measuring the transendothelial electrical resistance (TER). The Western blot analysis was used to determine the protein expression of glucose transporter-1 (GLUT-1), zonular occludens-1 (ZO-1), occludin, and myosin light chain kinase (MLCK) in endothelial cells. The mRNA expression of proinflammatory cytokines was detected by qRT-PCR. Results: Genetic overexpression of HIF-1α significantly increased the mRNA and protein expression of HIF-1α in endothelial cells. The overexpression of HIF-1α enhanced the hypoxia-induced increase of HIF-1α and GLUT-1 protein expression. HIF-1α overexpression not only exacerbated hypoxia-induced endothelial barrier dysfunction but also augmented hypoxia-induced up-regulation of MLCK protein expression. HIF-1α overexpression also enhanced IL-1β, IL-6 and TNF-α mRNA expression. Conclusion: We provide evidence that genetic overexpression of HIF-1α aggravates the hypoxia-induced endothelial barrier dysfunction via enhancing the up-regulation of MLCK protein expression caused by hypoxia, suggesting a potential role for HIF-1α in the pathogenesis of endothelial barrier dysfunction in hypoxia.

Background/Aims: The components of cigarette smoke (CS) have been implicated in the development of cancer as well as in cardiopulmonary diseases. We have previously reported increased oxidative stress in rat tissues induced by tobacco-specific toxins nicotine and 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Recently, we have also shown increased oxidative stress and associated inflammatory responses in various tissues after exposure to cigarette smoke. Methods: In this study, we have further investigated the effects of nose-only cigarette smoke exposure on mitochondrial functions and glutathione-dependent redox metabolism in tissues of BALB/C mice. Liver, kidney, heart and lung tissues were analyzed for oxidative stress, glutathione (GSH) and cytochrome P450 dependent enzyme activities and mitochondrial functions after exposure to smoke generated by 9 cigarettes/day for 4 days. Control mice were exposed to air only. Results: An increase in oxidative stress as observed by increased production of reactive oxygen species (ROS) and altered GSH metabolism was apparent in all the tissues, but lung and heart appeared to be the main targets. Increased expression and activity of CYP450 1A1 and 1A2 were also observed in the tissues after exposure to cigarette smoke. Mitochondrial respiratory dysfunction in the tissues, as observed by alterations in the activities of Complex I and IV enzymes, was also observed after exposure to cigarette smoke. SDS-PAGE and Western blot results also indicate that alterations in the expression of enzyme proteins were in accordance with the changes in their catalytic functions. Conclusion: These results suggest that even short term exposure of cigarette smoke have adverse effects on mitochondrial functions and redox homeostasis in tissues which may progress to further complications associated with chronic smoking.

Background/Aims: Accumulating evidence has suggested that free fatty acids (FFAs) interact with protein kinases and protein phosphatases. The present study examined the effect of FFAs on protein phosphatases and Akt. Methods: Activities of protein phosphatase 1 (PP1), protein phosphatase 2A (PP2A), and protein tyrosine phosphatase 1B (PTP1B) were assayed under the cell-free conditions. Phosphorylation of Akt was monitored in MSTO-211H human malignant pleural mesothelioma cells without and with knocking-down phosphatidylinositol 3 kinase (PI3K) or 3-phosphoinositide-dependent protein kinase-1 (PDK1). Results: In the cell-free assay, unsaturated FFAs (uFFAs) such as oleic, linoleic and linolenic acid and saturated FFAs (sFFAs) such as stearic, palmitic, myristic, and behenic acid markedly reduced PTP1B activity, with the potential for uFFAs greater than that for sFFAs. All the investigated sFFAs inhibited PP2A activity, but otherwise no inhibition was obtained with uFFAs. Both uFFAs and sFFAs had no effect on PP1 activity. Oleic acid phosphorylated Akt both on Thr308 and Ser473, while stearic acid phosphorylated Akt on Thr308 alone. The effects of oleic and stearic acid on Akt phosphorylation were abrogated by the PI3K inhibitor wortmannin or the PDK1 inhibitor BX912 and also by knocking-down PI3K or PDK1. Conclusion: The results of the present study indicate that uFFAs and sFFAs could activate Akt through a pathway along a PI3K/PDK1/Akt axis in association with PTP1B inhibition. © 2013 S. Karger AG, Basel.

Since the reversible phosphorylation of tyrosyl residues is a critical event in cellular signaling pathways activated by erythropoietin (Epo), attention has been focused on protein tyrosine phosphatases (PTPs) and their coordinated action with protein tyrosine kinases. The prototypic member of the PTP family is PTP1B, a widely expressed non-receptor PTP located both in cytosol and intracellular membranes via its hydrophobic C-terminal targeting sequence. PTP1B has been implicated in the regulation of signaling pathways involving tyrosine phosphorylation induced by growth factors, cytokines, and hormones, such as the downregulation of erythropoietin and insulin receptors. However, little is known about which factor modulates the activity of this enzyme. The effect of Epo on PTP1B expression was studied in the UT-7 Epo-dependent cell line. PTP1B expression was analyzed under different conditions by Real-Time PCR and Western blot, while PTP1B phosphatase activity was determined by a p-nitrophenylphosphate hydrolysis assay. Epo rapidly induced an increased expression of PTP1B which was associated with higher PTP1B tyrosine phosphorylation and phosphatase activity. The action of Epo on PTP1B induction involved Janus Kinase 2 (JAK2) and Phosphatidylinositol-3 kinase (PI3K). The results allow us to suggest for the first time that, besides modulating Epo/Epo receptor signaling, PTP1B undergoes feedback regulation by Epo.

Background: CD40 is an important costimulatory molecule in both celluar and humoral immune responses, involved in the pathogenic processes of chronic inflammatory diseases. Few studies were performed on the association of CD40 single nucleotide polymorphism (SNP) with chronic hepatitis B virus (HBV) infection. In this study, we studied whether the CD40-1C/T polymorphism had any effect on the progression of chronic HBV infection in Chinese population. Methods: CD40 -1C/T polymorphism in the 5'-untranslated region was analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 453 chronic HBV carriers, who were divided into asymptomatic HBV carriers (ASC), moderate chronic hepatitis B group (MCHB) and severe chronic hepatitis B group (SCHB). 202 healthy individuals in the same region were enrolled in this study as the controls. The CD40 expression on B lymphocytes was detected by flow cytometry. The concentrations of soluble CD40 (sCD40) in sera were assayed by a commercial ELISA kit. Results: Our results showed the frequencies of TT genotype and T allele of CD40-1C/T polymorphism were higher significantly in ASC than those in controls (P< 0.05), while this result was not found in either MCHB or SCHB. On the surface of B lymphocytes, the CD40 expression levels in the individuals with TT genotype were significantly lower than those with CC and CT genotypes in either ASC group or healthy controls (P<0.001). The sCD40 levels in the sera of ASC, MCHB and SCHB groups were significantly higher than the controls (P<0.001). Conclusions: The CD40 -1C/T polymorphism may contribute to the susceptibility of asymptomatic HBV carriers through its effect on cell-surface CD40 expression, which indicated CD40 signaling was involved in immune tolerance of chronic HBV infection. © 2015 S. Karger AG, Basel.

Unlabelled: Alcohol causes reactive hypoglycemia by attenuating the release of counter regulatory hormones, redistribution of pancreatic blood flow and direct stimulation of insulin secretion. Objective of this study was characterization of ethanol-induced insulin secretion. Signaling of ethanol- and glucose-induced insulin release from INS-1 and INS-1E cells was compared. Both cell lines responded similarly to all experimental interventions. In contrast to glucose, ethanol-induced insulin secretion was not hindered in calcium depleted medium or by addition of 10 microM BAPTA/AM (intracellular chelator). Inhibitor of protein kinase C Bisindolylmaleimide (3 microM) abolished glucose- but not ethanol-induced insulin secretion. Tetanus toxin (20 nM), inhibitor of SNARE proteins complex formation, blocked ethanol-induced insulin secretion. Both 5 mM N-ethylamaleimide and 10 microM ZnCl(2) (inhibitor of protein tyrosine phosphatases), which block disassembly of SNARE complexes and their further participation in exocytosis, increased basal insulin secretion. In contrast to glucose, already high insulin secretion was further increased after ethanol stimulation in either treatment. Conclusion: Signaling of ethanol-induced insulin secretion from INS-1 and INS-1E cell lines bypasses calcium and PKC involving steps, is sensitive to tetanus toxin but resistant to N-ethymaleimide and ZnCl(2). An extra pool of secretory vesicles not available for glucose is exploited for exocytosis after ethanol stimulation.

A voltage-gated calcium channel containing Cav2.3e (alpha1Ee) as the ion conducting pore has recently been detected in rat heart. Functional evidence for this Ca2+ channel to be involved in the regulation of heart beating, besides L- and T-type channels, was derived from murine embryos where the gene for Cav1.2 had been ablated. The remaining "L-type like" current component was not related to recombinant splice variants of Cav1.3 containing channels. As recombinant Cav2.3 channels from rat were reported to be weakly dihydropyridine sensitive, the spontaneous activity of the prenatal hearts from Cav2.3(-|-) mice was compared to that of Cav2.3(+|+) control animals to investigate if Cav2.3 could represent such a L-type like Ca(2+) channel. The spontaneous activity of murine embryonic hearts was recorded by using a multielectrode array. Between day 9.5 p.c. to 12.5 p.c., the beating frequency of isolated embryonic hearts from Cav2.3-deficient mice did not differ significantly from control mice but the coefficient of variation within individual episodes was more than four-fold increased in Cav2.3-deficient mice indicating arrhythmia. In isolated hearts from wild type mice, arrhythmia was induced by superfusion with a solution containing 200 nM SNX-482, a blocker of some R-type voltage gated Ca2+ channels, suggesting that R-type channels containing the splice variant Cav2.3e as ion conducting pore stabilize a more regular heart beat in prenatal mice.

We investigated the effect of resveratrol on proliferation and induction of apoptosis of INS-1E rat insulinoma cells by cell counting, crystal violet staining, flow cytometry and immunoblotting. Resveratrol treatment of INS-1E cells at concentrations > or =50 microM resulted in a dose-dependent inhibition of cell proliferation, accumulation of the cells in the S and G0/G1 phase and a significant increase of the percentage of apoptotic cells. This was paralleled by an increase of cell granularity, apoptotic volume decrease (AVD), exposure of phosphatidylserine at the outer leaflet of the plasma membrane, an increase of the 7-AAD signal and caspase activation. The AMP-kinase (AMPK) inhibitor compound C (10 microM) significantly inhibited cell proliferation and induced caspase activation within 48 hours but this effect was not modified by resveratrol suggesting that AMPK is not a major target involved in mediating the proapoptotic effect of resveratrol in INS-1E cells. Immunoblotting revealed a significant inhibition of Akt (PKB) phosphorylation by 100 muM resveratrol within 1 hour. Addition of insulin (10 microM) to the culture medium strongly enhanced basal Akt phosphorylation. This enhancement was significantly attenuated by 50 and 100 microM resveratrol. We conclude that the antiproliferative/proapoptotic effect of resveratrol on INS-1E cells is due to negative interference with Akt signaling and most likely disruption of auto/paracrine insulin signaling.

The function of β-cells is regulated by nutrient uptake and metabolism. The cells' metabolic state can be expressed as concentration ratios of AMP, ADP and ATP. Relative changes in these ratios regulate insulin release. An increase in the intracellular ATP concentration causes closure of K(ATP) channels and cell membrane depolarization, which triggers stimulus-secretion coupling (SSC). In addition to K(ATP) channels, the AMP-dependent protein kinase (AMPK), a major cellular fuel sensor in a variety of cells and tissues, also affects insulin secretion and β-cell survival. In a previous study we found that the widely used AMPK inhibitor compound C retards proliferation and induces apoptosis in the rat β-cell line INS-1E. We therefore tested the effects of AMPK activators (AICAR and metformin), and compound C on AMPK phosphorylation, insulin secretion, K(ATP) channel currents, cell membrane potential, intracellular calcium concentration, apoptosis and cell cycle distribution of INS-1E cells under standard cell culture conditions (11 mM glucose). Western blotting, ELISA, patch-clamp, calcium imaging and flow cytometry. We found that basal AMPK phosphorylation is enhanced by AICAR (1 mM) and metformin (1 mM) but remained unaffected by compound C (10 μM). Both AICAR and compound C stimulated basal insulin secretion whereas metformin had no effect. Pre-incubation with AICAR (1 mM) caused an inhibition of K(ATP) currents but did not significantly alter the average cell membrane potential (Vm) or the threshold potential of electrical activity. Acute administration of AICAR (300 μM) led to a depolarization of Vm, which was not due to an inhibition of the basal- or glucose-induced chloride conductance, and was not accompanied by elevations of intracellular calcium (Ca(i)). AICAR had no additive blocking effect on K(ATP) currents when applied together with tolbutamide. Compound C applied over 24 hours induced an increase in the percentage of cells positive for caspase activity, whereas AICAR (1 mM) applied for 48 hours was without effect. Medium glucose concentration <3 mM caused cell cycle arrest, caspase activation and an increase of cell granularity. We conclude that under standard cell culture conditions the AMPK modulators AICAR and compound C, but not metformin, stimulate insulin secretion by AMPK-independent mechanisms.

The metabolic coupling of insulin secretion by pancreatic beta cells is mediated by membrane depolarization due to increased glucose-driven ATP production and closure of K(ATP) channels. Alternative pathways may involve the activation of anion channels by cell swelling upon glucose uptake. In INS-1E insulinoma cells superfusion with an isotonic solution containing 20 mM glucose or a 30% hypotonic solution leads to the activation of a chloride conductance with biophysical and pharmacological properties of anion currents activated in many other cell types during regulatory volume decrease (RVD), i.e. outward rectification, inactivation at positive membrane potentials and block by anion channel inhibitors like NPPB, DIDS, 4-hydroxytamoxifen and extracellular ATP. The current is not inhibited by tolbutamide and remains activated for at least 10 min when reducing the extracellular glucose concentration from 20 mM to 5 mM, but inactivates back to control levels when cells are exposed to a 20% hypertonic extracellular solution containing 20 mM glucose. This chloride current can likewise be induced by 20 mM 3-Omethylglucose, which is taken up but not metabolized by the cells, suggesting that cellular sugar uptake is involved in current activation. Fluorescence resonance energy transfer (FRET) experiments show that chloride current activation by 20 mM glucose and glucose-induced cell swelling are accompanied by a significant, transient redistribution of the membrane associated fraction of ICln, a multifunctional 'connector hub' protein involved in cell volume regulation and generation of RVD currents.

Unlabelled: Cell swelling-induced insulin secretion represents an alternative pathway of stimulation of insulin secretion. INS-1E rat tumor beta cells do not release insulin in response to cell swelling in presence of Ca(2+) despite a good response to glucose challenge and appropriate increase in cell volume. Surprisingly, perifusion with Ca(2+)-depleted medium showed distinct secretory response of INS-1E cells to hypotonicity. Objective of this study was further characterization of the role of Ca(2+) in secretory process in INS-1 and INS-1E cell lines. Ca(2+) depleted hypotonic medium with 10 muM BAPTA/AM (intracellular chelator) induced insulin secretion from both types of cells. We demonstrated expression of L-type Ca(2+) channel Ca(v)1.2 and non-L-type Ca(2+) channels Ca(v)2.1 (P/Q-type), Ca(v)2.2 (N-type), and Ca(v)3.1 (T-type) in both cell lines. Inhibition of L type channel with nifedipine and/or P/Q type with omega-agatoxin IVA enabled distinct response to hypotonic medium also in INS-1E cells. Tetanus toxin (TeTx) in medium containing Ca(2+) and a group of calcium channel blockers inhibited hypotonicity-induced insulin secretion from INS-1 cells but not from INS-1E cells. Conclusion: Hypotonicity-induced insulin secretion from INS-1E cells is inhibited by extracellular Ca(2+), does not require intracellular Ca(2+) and is TeTx resistant.

Despite the presence of glucagon-like peptide-1 receptor (GLP-1R) in kidney tissues, its direct effect on diabetic nephropathy remains unclear. The transforming growth factor-β(1) (TGF-β(1)) and the connective tissue growth factor (CTGF) both induce extracellular matrix accumulation and persistent fibrosis in the glomerular mesangium of patients with diabetic nephropathy. Herein, we demonstrate that a GLP-1R agonist, exendin-4, exerts renoprotective effects through its influence on TGF-β(1) and CTGF in human mesangial cells (HMCs), cultured in a high glucose medium. HMCs, cultured in a high glucose medium, were used for the current study. The direct effect of exendin-4 on TGF-β(1) and CTGF expression was confirmed in HMCs. MDL-12330A (a specific adenylate cyclase inhibitor) and PKI14-22 (a protein kinase A inhibitor) were used to examine the role of the cAMP signaling pathway in exendin's anti-fibrosis action. The findings showed that exendin-4 inhibited the proliferation of HMCs, and upregulated the expression of TGF-β(1) and CTGF, induced by high glucose. The effect of exendin-4 is largely dependent on the activation of adenylate cyclase. This study provides new evidence that GLP-1 acts as an antifibrotic agent in HMCs.

Background/Aims: The 1α,25-dihydroxycholecalciferol (Vit. D) induces eNOS dependent nitric oxide (NO) production in human umbilical vein endothelial cells (HUVEC). To our knowledge, there are no reports directly relating Vit. D induced NO production to proliferation and/or migration in endothelial cells (EC). The aim of this study was to evaluate whether Vit. D addition to porcine EC could affect their proliferation and/or migration in a three-dimensional matrix via NO production. Materials and Methods: Porcine aortic endothelial cells (PAE) were used to evaluate Vit. D effects on cell proliferation and migration in a three-dimensional matrix. Results: Vit. D induced NO production in PAE cells. Moreover, it induced a significant increase in cellular proliferation and migration in a three-dimensional matrix. These effects were NO dependent, as inhibiting eNOS activity by L-NAME PAE migration was abrogated. This effect was strictly related to MMP-2 expression and apparently dependent on Vit. D and NO production. Conclusions: Vit. D can promote both endothelial cells proliferation and migration in a three-dimensional matrix via NO-dependent mechanisms. These findings cast new light on the role of Vit. D in the angiogenic process, suggesting new applications for Vit. D in such fields as tissue repair and wound healing.

Previous results indicate that enhanced glucose transporter (GLUT)1 expression mediates the deleterious effects of metabolic and hemodynamic perturbations leading to diabetic kidney disease. First screening for altered gene expression in GLUT1 overexpressing cells (GT1) by Affymetrix microarray analysis revealed upregulation of interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF) expression, which was verified by RT-PCR. Subsequently, IL-6 and VEGF protein production was more than 3-fold increased in the GT1 cells. This upregulation was independent from each other. Studies on the underlying transcriptional mechanisms by gelshift assays and siRNA approach implicated activation of AP-1 in the increased expression of both, IL-6 and VEGF. We found also increased nuclear protein levels of hypoxia-inducible factor (HIF)-1alpha and enhanced DNA binding activity to a hypoxia responsible element located in the VEGF promoter. Knock-down of HIF-1alpha reduced the VEGF expression to 50% with an additive effect of AP-1 gene silencing down to 24%. The IL-6 expression was not affected by reducing HIF-1alpha. In conclusion our results link increased GLUT1 levels leading to excess glucose metabolism under normoglycemic conditions and altered gene expression of pathogenetic factors involved in diabetic kidney disease.