-
[show abstract]
[hide abstract]
ABSTRACT: Liver X receptor α (LXRα) plays a critical role in the transcriptional control of lipid metabolism. LXR activation induces the expression of lipogenic genes, which promotes hepatic steatosis and steatohepatitis. However, the regulation of LXR is not fully understood. MicroRNAs (miRs) are regarded as important negative regulators of gene expression. In this study, we found that miR-1/miR-206 repressed LXRα-induced accumulation of lipid droplets in hepatocytes. In addtion, Bioinformatics analysis predicted a same putative target-site for miR-1/miR-206 located within the 3'-untranslated region (3'-UTR) of LXRα mRNA. The reporter assay revealed that miR-1/miR-206 directly targeted 3'-UTR of LXRα mRNA. Furthermore, miR-1/miR-206 repressed LXRα expression at both mRNA and protein levels, accompanied with the inhibition of expression of LXRα target genes, such as sterol-regulatory element binding protein 1c, fatty acid synthase, carbohydrate responsive element-binding protein and acetyl-CoA carboxylase 1, which are important effectors of LXRα implicated in lipogenesis. Moreover, ectopic expression of LXRα without 3'-UTR dramatically attenuated the miR-1/miR-206-induced decrease of lipogenic genes and lipid droplet accumulation. Taken together, we for the first time demonstrated that miR-1/miR-206 attenuated LXRα-induced lipogenesis by targeting 3'-UTR of LXRα mRNA, suggesting that miR-1/miR-206-LXRα pathway may be a novel target for the treatment of lipogenesis-associated diseases.
Cellular signalling 03/2013; · 4.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: BACKGROUND: MicroRNAs (miRNAs) emerge as new important regulators of lipid homeostasis by regulating corresponding genes. MiR-613 is a newly discovered microRNA, of which the biological function is unknown. A recent report has shown that miR-613 downregulates liver X receptor ¿ (LXR¿), a ligand-activated nuclear receptor playing an important role in the regulation of lipid metabolism. The purpose of this study is to explore the effect and the molecular basis of miR-613 on lipogenesis in HepG2 cells. METHODS: HepG2 cells were transiently transfected with miR-613 mimic or control microRNA. Real time PCR, Western blot, Luciferase reporter assay and Oil Red O staining were employed to examine the expression of LXR¿ and its target genes involved in lipogenesis, binding site for miR-613 in 3¿-untranslated region (3¿-UTR) of LXR¿ mRNA and lipid droplet accumulation in the cells. RESULTS: MiR-613 dramatically suppressed the expression of LXR¿ and its target genes including sterol-regulatory element binding protein 1c (SREBP-1c), fatty acid synthase (FAS), carbohydrate responsive element-binding protein (ChREBP) and acetyl-CoA carboxylase (ACC). Reporter assay showed that miR-613 directly bound to 3¿-UTR of LXR¿ mRNA. Moreover, miR-613 significantly repressed LXR¿-induced lipid droplet accumulation in HepG2 cells. Ectopic expression of LXR¿ without 3¿-UTR markedly attenuated the miR-613-mediated downregulation of LXR¿¿s target genes and LXR¿-induced lipid droplet accumulation. CONCLUSIONS: MiR-613 suppresses lipogenesis by directly targeting LXR¿ in HepG2 cells, suggesting that miR-613 may serve as a novel target for regulating lipid homeostasis.
Lipids in Health and Disease 03/2013; 12(1):32. · 2.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: PURPOSE: The aim of the present study was to evaluate whether the anti-Rheumatoid arthritis (RA) effect of curcumin is associated with the regulation of B cell-activating factor belonging to the TNF family (BAFF) production. METHODS: Collagen-induced arthritis (CIA) was induced in DBA/1 J mice by immunization with bovine type II collagen. To investigate the anti-arthritic effect of curcumin in the CIA model, mice were injected intraperitoneally with curcumin (50 mg/kg) on every other day either from day 1 or from day 28 after the first immunization. The clinical severity of arthritis was monitored. BAFF, interleukin-6 (IL-6) and interferon-γ (IFNγ) production in serum were measured. Furthermore, the effect of curcumin on IFNγ-induced BAFF expression and transcriptional activation in B lymphocytes was determined by qPCR, Western Blot, and luciferase assay. Finally, IFNγ related signal transducers and activators of transcription 1 (STAT1) signaling in B lymphocytes were studied using Western Blot. RESULTS: Curcumin dramatically attenuated the progression and severity of CIA in DBA/1 J mice, accompanied with decrease of BAFF production in serum and spleen cells as well as decrease of serum IFNγ and IL-6. Treatment of B lymphocytes with curcumin suppressed IFNγ-induced BAFF expression, STAT1 phosphorylation and nuclear translocation, suggesting that curcumin may repress IFNγ-induced BAFF expression via negatively interfering with STAT1 signaling. CONCLUSION: The results of the present study suggest that suppression of BAFF production may be a novel mechanism by which curcumin improves RA.
Journal of Clinical Immunology 11/2012; · 3.08 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Octamer-binding transcription factor 4 (Oct4), an important embryonic transcriptional factor, is highly expressed in several tumors and is considered as a hallmark of cancer stem cells. Knowledge about the expression and regulatory mechanisms of Oct4 can contribute to the treatment of cancers. As for cervical cancer, however, details remain obscure about Oct4 expression and its regulatory mechanism. In this study, we found that the level of Oct4 in human papillomavirus 16 (HPV16)- positive cervical cancer cells (CaSki cells) was higher than that in HPV-negative cervical cancer cells (C-33A cells), whereas both the level of histone deacetylase 1 (HDAC1) and DNA methyltransferase 3A (DNMT3A) were lower in CaSki cells than those in C-33A cells. Treatment with valproic acid, an HDAC inhibitor, could significantly increase the expression of Oct4 in C-33A cells, but only slightly increased Oct4 in CaSki cells. Co-immunoprecipitation assays showed that HDAC1 and DNMT3A existed in a common complex. The co-immunoprecipitated DNMT3A or HDAC1 was dose-dependently decreased with valproic acid treatment. These results indicated that HDAC1/DNMT3A-containing complex is associated with the suppression of Oct4 in cervical cancer cells, and the activity of HDAC1 is required in the repression of Oct4.
Biochemistry (Moscow) 08/2012; 77(8):934-40. · 1.06 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Cytokine inducible SH2-containing protein (CISH), which negatively regulates cytokine signaling by inhibiting JAK2/STAT5 activity, is regarded as a therapeutic target for inflammatory diseases. Farnesoid X receptor (FXR), a ligand-activated transcription factor, has been proposed to play a protective function in the inflammatory responses. However, the role of FXR in modulation of CISH expression is unknown. In the present study, we for the first time identified that in human hepatoma cell line HepG2 the activation of FXR by the natural agonist chenodeoxycholic acid (CDCA) and the synthetic specific agonist GW4064 upregulated CISH at both transcriptional and translational levels, and inhibited interleukin (IL)6-induced STAT5 activation. Moreover, the in vivo experiment demonstrated that gavaging mice with CDCA increased CISH expression and reduced basal STAT5 phosphorylation in liver tissues. Reporter assay showed that FXR agonists enhanced the transcriptional activity of CISH promoter. These data suggest that FXR may serve as a novel molecular target for manipulating CISH expression in hepatocytes. FXR-mediated upregulation of CISH may play an important role in the homeostasis of cytokine signal networks and be beneficial to control cytokine-associated inflammatory diseases.
Journal of interferon & cytokine research: the official journal of the International Society for Interferon and Cytokine Research 07/2012; · 1.63 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Because of the anti-inflammatory actions of farnesoid X receptor (FXR) agonists, FXR has received much attention as a potential therapeutic target. However, the molecular mechanisms of actions have not yet been elucidated. In the present study, we reported that in the animal model of LPS-induced liver injury, administration of the FXR natural ligand CDCA could attenuate hepatocyte inflammatory damage, reduce transaminase activities, suppress inflammation mediators (IL-6, TNF-α and ICAM-1) expression and inhibit STAT3 phosphorylation. These protective effects of FXR were accompanied by an increased expression of suppressor of cytokine signaling 3 (SOCS3), which is a negative feedback regulator of cytokine-STAT3 signaling. We then demonstrated that the beneficial effects of FXR agonist in STAT3 activation were weakened by small interfering RNA-mediated SOCS3 knockdown in hepacytes. Moreover we observed both natural ligand CDCA and synthetic ligand GW4064 could upregulate SOCS 3 expression by enhancing the promoter activity in hepatocytes. These results suggest modulation of SOCS3 expression may represent a novel mechanism through which FXR activation could selectively affect cytokine bioactivity in inflammation response. FXR ligands may be potentially therapeutic in the treatment of liver inflammatory diseases via SOCS3 induction.
Cellular signalling 04/2012; 24(8):1658-64. · 4.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The farnesoid X receptor (FXR) is a member of the nuclear receptor superfamily that is highly expressed in liver, kidney, adrenal gland, and intestine. It plays an important role in regulating the progression of several cancers including hepatocellular carcinoma (HCC). So it is necessary to study the regulation of FXR. In this study, we found that the expression of miR-421 was inversely correlated with FXR protein level in HCC cell lines. Treatment with miR-421 mimic repressed FXR translation. The reporter assay revealed that miR-421 targeted 3' untranslated region of human FXR mRNA. Furthermore, downregulation of FXR by miR-421 promoted the proliferation, migration, and invasion of HCC cells. These results suggest that miR-421 may serve as a novel molecular target for manipulating FXR expression in hepatocyte and for the treatment of HCC.
Molecular Cancer Research 03/2012; 10(4):516-22. · 4.29 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Overexpression of B lymphocyte stimulator (BLyS) is closely involved in the pathogenesis and progression of some autoimmune diseases. Curcumin, a pharmacologically safe agent, has been shown to possess potent anti-inflammatory properties. However, it is not clear whether curcumin affects the expression of BLyS. In this study, we report that curcumin inhibits the expression of BLyS and that a DNA-binding site for the transcriptional factor NF-κB in the BLyS promoter region is required for this regulation. Moreover, we find that curcumin reduces the DNA-binding activity of NF-κB to the BLyS promoter region and suppresses nuclear translocation of p65, suggesting that curcumin may suppress BLyS expression via negatively interfering with NF-κB signaling. These results suggest that curcumin may serve as a novel therapeutic agent in the treatment of autoimmune diseases by targeting BLyS.
European journal of pharmacology 10/2010; 650(1):451-7. · 2.59 Impact Factor
-
Fan Chao,
Wei Gong,
Yingru Zheng,
Yuan Li, Gang Huang,
Min Gao,
Jialin Li,
Ramalinga Kuruba,
Xiang Gao,
Song Li,
Fengtian He
[show abstract]
[hide abstract]
ABSTRACT: The farnesoid X receptor (FXR), a member of the nuclear receptor superfamily, has been proposed to play an important role in the pathogenesis of cardiovascular diseases by regulating the metabolism and transport of cholesterol and triglyceride. Scavenger receptor class B type I (SR-BI), a high-density lipoprotein receptor, plays an important role in decreasing lipid metabolism-associated cardiovascular diseases by regulating reverse cholesterol transport. Recent studies have shown that SR-BI expression is upregulated by several nuclear receptors. However, the role of FXR in the regulation of SR-BI expression is not well known. In the present study, we investigate the regulation of SR-BI by FXR in hepatocyte and the corresponding mechanism.
Treatment of human hepatoma cell line HepG2 with FXR ligands resulted in upregulation of SR-BI at the levels of both mRNA and protein. Reporter assays showed that activation of FXR significantly enhanced the SR-BI promoter activity. Electrophoretic mobility shift and chromatin immunoprecipitation assays indicated that FXR induced SR-BI expression by binding to a novel FXR element (FXRE), a directed repeat DNA motif, DR8 (-703 AGGCCAcgttctagAGCTCA -684). The in vivo experiment demonstrated that gavaging mice with a natural ligand of FXR increased SR-BI expression in liver tissues.
FXR can directly upregulate SR-BI expression in hepatocyte, and DR8 is a likely novel FXRE that is involved in SR-BI regulation. FXR may serve as a novel molecular target for manipulating SR-BI expression in hepatocyte.
Atherosclerosis 10/2010; 213(2):443-8. · 3.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Luffin-a, a single-chain Type I ribosome-inactivating protein, which is known to be the most toxic of the luffin family and apparently possesses antitumor activity, was isolated from Luffa cylindrica seeds. In the present study, mature alpha-luffin was cloned from L. cylindrica and it was found that mature alpha-luffin shared 96% amino acid similarity with luffin-a. The recombinant mature alpha-luffin was successfully expressed in a partly soluble form in Escherichia coli after optimization of expression conditions. The effects of the recombinant protein on bacterial growth and its in vitro protein synthesis inhibition activity were tested. Then, its antitumor activities against different human cancer cell lines were evaluated by CCK-8 assay and flow cytometry. The results indicated that the recombinant alpha-luffin was slightly toxic to E. coli. It could inhibit protein synthesis in the rabbit reticulocyte lysate system. At the same time, it inhibited the growth of the tumor cell lines in a dose- and time-dependent manner. Additionally, recombinant alpha-luffin was able to induce cell death by apoptosis. The cytotoxicity of alpha-luffin towards tumor cells makes it a potential antitumor agent.
Acta Biochimica et Biophysica Sinica 08/2010; 42(8):585-92. · 1.38 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: High mobility group box chromosomal protein 1 (HMGB1) is a lethal mediator of systemic inflammation, and its A box domain is isolated as an antagonist of HMGB1. To enhance its expression level and its anti-HMGB1 effect, the A box cDNA was coupled with the sequence encoding lectin-like domain of thrombomodulin (TMD1). The fusion DNA fragment was ligated into the prokaryotic expression vector pQE-80L to construct the recombinant plasmid pQE80L-A/TMD1. The plasmid was then transformed into Escherichia coli DH5alpha, and the recombinant fusion protein A/TMD1 was expressed at 37 degrees C for 4 h, with induction by IPTG at the final concentration of 0.2 mM. The expression level of the fusion protein was up to 40% of the total cellular protein. The fusion protein was purified by Ni-NTA chromatography and the purity was about 95%. After passing over a polymyxin B column to remove any contaminating lipopolysaccharides, the purified protein was tested for its anti-inflammatory activity. Our data show that A/TMD1 significantly inhibits HMGB1-induced TNF-alpha release and might be useful in treating HMGB1-elevated sepsis.
Biochemistry (Moscow) 04/2010; 75(4):466-71. · 1.06 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: HMGB1, composed of the A box, B box, and C tail domains, is a critical proinflammatory cytokine involved in diverse inflammatory diseases. The B box mediates proinflammatory activity, while the A box alone acts as a specific antagonist of HMGB1. The C tail contributes to the spatial structure of A box and regulates HMGB1 DNA binding specificity. It is unknown whether the C tail can enhance the anti-inflammatory effect of A box. In this study, we generated fusion proteins consisting of the A box and C tail, in which the B box was deleted and the A box and C tail were linked either directly or by the flexible linker sequence (Gly4Ser)3. In vitro and in vivo experiments showed that the two fusion proteins had a higher anti-inflammatory activity compared to the A box alone. This suggests that the fused C tail enhances the anti-inflammatory effect of the A box.
Journal of Biomedicine and Biotechnology 01/2010; 2010:915234. · 2.44 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Antibacterial activity is a novel function of high-mobility group box 1 (HMGB1). However, the functional site for this new effect is presently unknown.
In this study, recombinant human HMGB1 A box and B box (rHMGB1 A box, rHMGB1 B box), recombinant human HMGB1 (rHMGB1) and the truncated C-terminal acidic tail mutant (tHMGB1) were prepared by the prokaryotic expression system. The C-terminal acidic tail (C peptide) was synthesized, which was composed of 30 amino acid residues. Antibacterial assays showed that both the full length rHMGB1 and the synthetic C peptide alone could efficiently inhibit bacteria proliferation, but rHMGB1 A box and B box, and tHMGB1 lacking the C-terminal acidic tail had no antibacterial function. These results suggest that C-terminal acidic tail is the key region for the antibacterial activity of HMGB1. Furthermore, we prepared eleven different deleted mutants lacking several amino acid residues in C-terminal acidic tail of HMGB1. Antibacterial assays of these mutants demonstrate that the amino acid residues 201-205 in C-terminal acidic tail region is the core functional site for the antibacterial activity of the molecule.
In sum, these results define the key region and the crucial site in HMGB1 for its antibacterial function, which is helpful to illustrating the antibacterial mechanisms of HMGB1.
Journal of Biomedical Science 09/2009; 16:83. · 2.01 Impact Factor
-
Huiguang Gao,
Aina Bian,
Yingru Zheng,
Rongfen Li,
Qing Ji, Gang Huang,
Daqiang Hu,
Li Zhang,
Wei Gong,
Ying Hu,
Fengtian He
[show abstract]
[hide abstract]
ABSTRACT: B cell activating factor belonging to the TNF family (BAFF) is a novel member of the tumor necrosis factor (TNF) ligand family and plays an important role in B lymphocyte maturation and survival. Overexpression of BAFF is closely involved in the pathogenesis and progression of many kinds of autoimmune disorders; therefore, BAFF has been considered as an ideal therapeutic target for these conditions. In this study, we generated several candidate immune inhibitors of human BAFF by conjugating foreign immunodominant T-helper cell (Th) epitopes to the N- or C-terminus of five BAFF mutants. The recombined proteins were successfully expressed in Escherichia coli (E. coli) and purified by Ni-NTA chromatography. BALB/c mice immunized with the recombinant proteins produced high levels of anti-BAFF antibodies, and their sera inhibited the lymphocyte proliferation-inducing activity of recombinant soluble BAFF and natural soluble BAFF. Moreover, antibodies cross-reactive with BAFF were detected in sera from hu-SCID mice immunized with the recombinant proteins. These results indicated that the recombinant BAFF mutants modified with Th epitopes could induce neutralizing antibodies against BAFF in vivo. This study may provide a valuable strategy for treating BAFF-associated autoimmune diseases.
FEBS Letters 03/2007; 581(4):581-6. · 3.54 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The DNA encoding soluble B lymphocyte stimulator (134-285 amino acids, sBLyS) mutant with residues 217-224 replaced by two glycines (named msBLyS) was constructed. The sequence encoding a foreign immunodominant T-helper epitope from ovalbumin (OVA) was then coupled to the 5'-end of msBLyS cDNA. After being sequenced, the recombinant DNA was ligated into the prokaryotic expression vector pQE-80L. The recombinant protein was produced in E. coli DH5alpha after induction with IPTG with the yield of more than 40% of total bacterial protein. The recombinant protein was purified with Ni-NTA chromatography and Sepharcryl S200 chromatography to a purity of more than 98%. The BALB/c mice, immunized with the recombinant protein, produced anti-BLyS antibodies at a high level, which indicated that the recombinant BLyS mutant modified with T-helper epitope elicited polyclonal antibodies with cross-reactivity with BLyS in vivo. This recombinant protein may therefore be used as immune inhibitor of BLyS for treating BLyS -associated autoimmune diseases.
Biotechnology Letters 11/2006; 28(20):1649-54. · 1.68 Impact Factor
