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Qin Lv,
Xian-Fang Meng,
Fang-Fang He, Shan Chen,
Hua Su,
Jing Xiong,
Pan Gao,
Xiu-Juan Tian,
Jian-She Liu,
Zhong-Hua Zhu,
Kai Huang,
Chun Zhang
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ABSTRACT: Current evidence suggests high serum uric acid may increase the risk of type 2 diabetes, but the association is still uncertain. The aim of the study was to evaluate the association between serum uric acid and future risk of type 2 diabetes by conducting a meta-analysis of prospective cohort studies.
We conducted a systematic literature search of the PubMed database through April 2012. Prospective cohort studies were included in meta-analysis that reported the multivariate adjusted relative risks (RRs) and the corresponding 95% confidence intervals (CIs) for the association between serum uric acid and risk of type 2 diabetes. We used both fix-effects and random-effects models to calculate the overall effect estimate. The heterogeneity across studies was tested by both Q statistic and I(2) statistic. Begg's funnel plot and Egger's regression test were used to assess the potential publication bias.
We retrieved 7 eligible articles derived from 8 prospective cohort studies, involving a total of 32016 participants and 2930 incident type 2 diabetes. The combined RR of developing type 2 diabetes for the highest category of serum uric acid level compared with the lowest was 1.56(95% CI, 1.39-1.76). Dose-response analysis showed the risk of type 2 diabetes was increased by 6% per 1 mg/dl increment in serum uric acid level (RR 1.06, 95% CI: 1.04-1.07). The result from each subgroup showed a significant association between serum uric acid and risk of type 2 diabetes. In sensitive analysis, the combined RR was consistent every time omitting any one study. Little evidence of heterogeneity and publication bias was observed.
Our meta-analysis of prospective cohort studies provided strong evidence that high level of serum uric acid is independent of other established risk factors, especially metabolic syndrome components, for developing type 2 diabetes in middle-aged and older people.
PLoS ONE 01/2013; 8(2):e56864. · 4.09 Impact Factor
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ABSTRACT: This study was aimed to construct eukaryotic expression vectors carrying the small hairpin RNA (shRNA) targeting TRPC6 gene and investigate the effect of TRPC6 knockdown on puromucin aminonucleoside (PAN)-induced podocyte injury. Two DNA sequences containing the small hairpin structure targeting TRPC6 were designed, synthesized and then inserted into the green fluorescence protein (GFP)-contained plasmids (pGC) to establish the plasmids pGCsi-TRPC6A and pGCsi-TRPC6B. Plasmids expressing scrambled shRNA were used as negative control and named pGCsi-NC. These plasmids were transfected into a conditionally immortalized murine podocyte cell line by using liposome. Flow cytometry was used to examine the transfection efficiency. TRPC6 mRNA and protein expression levels were detected by RT-PCR and Western blotting. Cultured podocytes were divided into four groups: control group, PAN treatment group, PAN+TRPC6 shRNA transfected group and PAN+scrambled shRNA transfected group. The paracelluar permeability to BSA was evaluated by Millicell-PCF Inserts and cell viability was measured by the trypan blue assay. Immunofluorescent assay was used to observe the distribution of α-actinin-4 and α-tubulin. The results showed that the transfection efficiency of the shRNA expression vector was about 45%. Expression levels of TRPC6 mRNA and protein were downregulated after transfection with pGCsi-TRPC6A and pGCsi-TRPC6B. Knocking down TRPC6 gene could effectively reverse the PAN-induced increase in the paracelluar permeability to BSA. The distribution of α-actinin-4 and α-tubulin was disrupted after treatment with PAN, which was reversed by knocking down TRPC6 gene. It was concluded that knocking down TRPC6 gene could effectively prevent podocytes from the permeability increase induced by PAN, which may be related to the regulation of podocyte cytoskeleton.
Journal of Huazhong University of Science and Technology 06/2012; 32(3):340-5. · 0.38 Impact Factor
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Shan Chen,
Fang-Fang He,
Hui Wang,
Zhan Fang,
Ning Shao,
Xiu-Juan Tian,
Jian-She Liu,
Zhong-Hua Zhu,
Yu-Mei Wang,
Sheng Wang,
Kai Huang,
Chun Zhang
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ABSTRACT: Albumin, which is the most abundant component of urine proteins, exerts injurious effects on renal cells in chronic kidney diseases. However, the toxicity of albumin to podocytes is not well elucidated. Here, we show that a high concentration of albumin triggers intracellular calcium ([Ca(2+)](i)) increase through mechanisms involving the intracellular calcium store release and extracellular calcium influx in conditionally immortalized podocytes. The canonical transient receptor potential-6 (TRPC6) channel, which is associated with a subset of familial forms of focal segmental glomerulosclerosis (FSGS) and several acquired proteinuric kidney diseases, was shown to be one of the important Ca(2+) permeable ion channels in podocytes. Therefore we explored the role of TRPC6 on albumin-induced functional and structural changes in podocytes. It was found that albumin-induced increase in [Ca(2+)](i) was blocked by TRPC6 siRNA or SKF-96365, a blocker of TRP cation channels. Long-term albumin exposure caused an up-regulation of TRPC6 expression in podocytes, which was inhibited by TRPC6 siRNA. Additionally, the inhibition of TRPC6 prevented the F-actin cytoskeleton disruption that is induced by albumin overload. Moreover, albumin overload induced expression of the endoplasmic reticulum (ER) stress protein GRP78, led to caspase-12 activation and ultimately podocyte apoptosis, all of which were abolished by the knockdown of TRPC6 using TRPC6 siRNA. These results support the view that albumin overload may induce ER stress and the subsequent apoptosis in podocytes via TRPC6-mediated Ca(2+) entry.
Cell calcium 09/2011; 50(6):523-9. · 4.29 Impact Factor
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ABSTRACT: Proteinuria is an exacerbating factor of chronic kidney diseases, leading to glomerulosclerosis. However, the molecular mechanisms mediating protein overload-induced podocyte injury are poorly understood. Recent studies have shown that apoptosis mediated by endoplasmic reticulum (ER) stress participated in the progression of a variety of kidney diseases. In the present study, we investigated the role of CD2-associated protein (CD2AP) in protein overload-induced ER stress and subsequent podocyte apoptosis. Conditionally immortalized mouse podocytes were cultured in vitro and treated with different concentrations of bovine serum albumin (BSA). In addition, CD2AP eukaryotic expression vector or siRNA was transfected into podocytes before exposed to BSA. Albumin endocytosis and podocyte apoptosis were visualized by confocal microscopy. The subcellular organelles were observed by transmission electron microscopy. The expressions of GRP78, caspase-12 and CD2AP were detected by RT-PCR or Western blot analysis. It was found that albumin was endocytosed by podocytes in a time-dependent manner. Accumulation of albumin in podocytes induced ER stress and apoptosis in a concentration-dependent manner as indicated by upregulation of GRP78 and caspase-12. Meanwhile, the subcellular organelles were disrupted and the expression of CD2AP was downregulated by high concentration of albumin. Transfection of CD2AP eukaryotic expression vector into podocytes increased CD2AP expression, depressed GRP78 and caspase-12 expressions, and inhibited podocyte apoptosis. In contrast, transfection of CD2AP siRNA deteriorated the above changes induced by BSA. It is concluded protein overload induces podocyte apoptosis via ER stress and CD2AP may play a crucial role in albumin overload-induced ER stress and apoptosis in podocytes.
Gene 06/2011; 484(1-2):18-25. · 2.34 Impact Factor
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ABSTRACT: To investigate the protective effects of eplerenone on adriamycin-induced renal injury and the possible mechanisms involved, 36 male Sprague-Dawley rats were randomly divided into control group, adriamycin nephropathy (AN) group and eplerenone-treated group (100 mg·kg(-1)·d(-1) eplerenone). Blood pressure, 24-h urinary protein, serum potassium, sodium and creatinine were measured 28 days after adriamycin injection (a single tail intravenous injection of 6.5 mg/kg adriamycin). The morphological changes of renal tissues were observed by light and electron microscopy. Immunohistochemistry and Western blotting were performed to examine the expression of TGF-β(1) and desmin in renal cortex. The results showed that 28 days after adriamycin injection, there were no significant changes in the level of serum potassium, sodium, creatinine concentrations and blood pressure values in the rats of the three groups. Meanwhile, the 24-h proteinuria excretion in the AN group was significantly higher than that in the control group (P<0.01), but that in the eplerenone-treated group was substantially reduced when compared with that in the AN group (P<0.05). Mild mesangial cell proliferation and matrix expansion, diffuse deformation and confluence of foot processes in podocytes were found in the AN group. By contrast, rats in the eplerenone-treated group exhibited obvious attenuation of these morphological lesions. The protein expression of TGF-β(1) and desmin in the AN group was markedly up-regulated in contrast to that in the control group (P<0.01), whereas that in the eplerenone-treated group was much lower than in the AN group (P<0.05). It was concluded that eplerenone may ameliorate the proteinuria and the development of pathological alteration in adriamycin-induced nephropathy presumably via the inhibition of cytokine release, and restore the morphology of podocytes independent of its blood pressure-lowing effects.
Journal of Huazhong University of Science and Technology 06/2011; 31(3):329-34. · 0.38 Impact Factor
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Fang-Fang He,
Chun Zhang, Shan Chen,
Bing-Qing Deng,
Hui Wang,
Ning Shao,
Xiu-Juan Tian,
Zhan Fang,
Xi-Feng Sun,
Jian-She Liu,
Zhong-Hua Zhu,
Xian-Fang Meng
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ABSTRACT: Proteinuria is a well-established exacerbating factor of chronic kidney diseases. However, the harmful effects of protein overload on podocytes and the underlying mechanisms are still poorly understood. In the present study, we examined the effects of high concentrations of albumin on podocytes and investigated the role of CD2AP (CD2-associated protein) in albumin overload-induced podocyte apoptosis. Conditionally immortalized mouse podocytes were cultured in vitro and treated with different concentrations of BSA. In addition, CD2AP eukaryotic expression vector or siRNA (small interfering RNA) was transfected into podocytes before they were exposed to BSA. Podocyte apoptosis, expressions of active caspase-3 (p17) and CD2AP, and the distribution of F-actin cytoskeleton were detected by flow cytometry, Western-blot analysis and fluorescent staining respectively. It was found that exposure of podocytes to BSA induced podocyte apoptosis in a concentration-dependent manner that was accompanied by up-regulation of active caspase-3, the disruption of F-actin cytoskeleton, and decreased expression of CD2AP. Transfection of CD2AP eukaryotic expression vector into podocytes increased CD2AP expression, partially restored F-actin distribution, blocked active caspase-3 expression and inhibited podocyte apoptosis. In contrast, transfection of CD2AP siRNA deteriorated the above changes induced by BSA. It is concluded that protein overload induces podocyte apoptosis via the down-regulation of CD2AP and subsequent disruption of cytoskeleton of podocytes, and CD2AP may play an important role in protein overload-induced podocyte injury.
Cell Biology International 12/2010; 35(8):827-34. · 1.48 Impact Factor
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ABSTRACT: This study examined the effect of sulodexide on podocyte injury in rats with adriamycin nephropathy (AN). A total of 36 healthy male SD rats were randomly assigned to three groups: control group, AN group and sulodexide treatment group. Rat models of AN were established by a single tail intravenous injection of adriamycin (6.5 mg/kg) in both AN group and sulodexide treatment group. Sulodexide (10 mg/kg) was administered the rats in the treatment group once daily by garage from the first day of model establishment until the 14th day or the 28th day. Samples of 24-h urine and renal cortex tissues were harvested at day 14, 28 after the model establishment. Excretion of 24-h urinary protein was measured by Coomassie brilliant blue method. The pathological changes in renal tissues were observed by light microscopy and electron microscopy respectively. Heparanase mRNA was detected by RT-PCR. Expressions of desmin, CD2AP and heparanase were determined by immunohistological staining. The results showed that the expressions of heparanase mRNA and protein were increased in the glomeruli of AN rats at day 14 and 28 after the model establishment, which was accompanied by the increased expression of desmin and CD2AP. The mRNA and protein expression of heparanase was decreased in the sulodexide-treated rats as compared with AN rats at day 14 and 28. And, the protein expression of desmin and CD2AP was reduced as with heparanase in the sulodexide- treated rats. Proteinuria and podocyte foot process effacement were alleviated in the AN rats after sulodexide treatment. There was a positive correlation between the expression of heparanase and the expression of desmin and CD2AP (as well as 24-h urinary protein excretion). It was concluded that increased heparanase is involved in podocyte injury. Sulodexide can maintain and restore podocyte morphology by inhibiting the expression of heparanase in AN.
Journal of Huazhong University of Science and Technology 12/2009; 29(6):715-9. · 0.38 Impact Factor
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ABSTRACT: To investigate the effects of albumin on the production of matrix metalloproteinases-2 (MMP-2) and matrix metalloproteinases-9 (MMP-9) in podocytes. Podocytes were treated with bovine serum albumin (BSA) at the concentration of 0.1, 0.5, 1, 2 g/L, respectively. Conditioned media were harvested 12, 24, 48 and 72 h after the treatment. The expression of MMP-2 and MMP-9 was assayed by gelatin zymography, RT-PCR and Western blotting analysis. Our results showed that in comparison with the control group, BSA increased the expression of MMP-2 and MMP-9 mRNA and protein in a dose- and time-dependent manner (P<0.05). Meanwhile, the enzymatic activities of MMP-2 and MMP-9 in the culture supernatants of podocytes were also increased (P<0.05). It is concluded that albumin up-regulated the expression of MMP-2 and MMP-9 at gene and protein levels in a time- and dose-dependent manner.
Journal of Huazhong University of Science and Technology 12/2009; 29(6):710-4. · 0.38 Impact Factor
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ABSTRACT: Trichosanthin (TCS) is a type I ribosome-inactivating protein that plays dual role of plant toxin and anti-viral peptide. The sorting mechanism of such an exogenous protein is in long pursuit. Here, we examined TCS trafficking in cells expressing the HIV-1 scaffold protein Gag, and we found that TCS preferentially targets the Gag budding sites at plasma membrane or late endosomes depending on cell types. Lipid raft membrane but not the Gag protein mediates the association of TCS with viral components. After Gag budding, TCS is then released in association with the virus-like particles to generate TCS-enriched virions. The resulting TCS-enriched HIV-1 exhibits severely impaired infectivity. Overall, the observations indicate the existence of a unique and elaborate sorting strategy for hijacking HIV-1.
Biochemical and Biophysical Research Communications.
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ABSTRACT: It was hypothesized that homologous desensitization regulates signal transduction from the beta-adrenergic receptor in the ocular ciliary epithelium to affect the circadian rhythm of aqueous humor secretion. β-arrestin-1 was cloned from the rabbit ciliary epithelium, and the full length cDNA used as a probe for Northern blot analysis to examine the diurnal expression of β-arrestin mRNA. Protein expression of β-arrestin-1 at intervals during the circadian cycle of aqueous secretion showed a decrease in β-arrestin expression when maximal activation of the β-adrenergic receptor is known to increase secretion. Diurnal expression of β-arrestin suggests that homologous desensitization can regulate the circadian rhythm of aqueous flow.
Experimental Eye Research.
