ABSTRACT
<p><b>OBJECTIVE</b>Interferon-γ (IFN-γ) plays an important role in apoptosis and was shown to increase the risk of diabetes. Visfatin, an adipokine, has anti-diabetic, anti-tumor, and regulating inflammatory properties. In this study we investigated the effect of visfatin on IFN-γ-induced apoptosis in rat pancreatic β-cells.</p><p><b>METHODS</b>The RINm5F (rat insulinoma cell line) cells exposed to IFN-γ were treated with or without visfatin. The viability and apoptosis of the cells were assessed by using MTT and flow cytometry. The expressions of mRNA and protein were detected by using real-time PCR and western blot analysis.</p><p><b>RESULTS</b>The exposure of RINm5F cells to IFN-γ for 48 h led to increased apoptosis percentage of the cells. Visfatin pretreatment significantly increased the cell viability and reduced the cell apoptosis induced by IFN-γ. IFN-γ-induced increase in expression of p53 mRNA and cytochrome c protein, decrease in mRNA and protein levels of anti-apoptotic protein Bcl-2 were attenuated by visfatin pretreatment. Visfatin also increased AMPK and ERK1/2 phosphorylation and the anti-apoptotic action of visfatin was attenuated by the AMPK and ERK1/2 inhibitor.</p><p><b>CONCLUSION</b>These results suggested that visfatin protected pancreatic islet cells against IFN-γ-induced apoptosis via mitochondria-dependent apoptotic pathway. The anti-apoptotic action of visfatin is mediated by activation of AMPK and ERK1/2 signaling molecules.</p>
Subject(s)
Animals , Rats , Adenylate Kinase , Metabolism , Apoptosis , Physiology , Cell Line , Cytokines , Physiology , Flow Cytometry , Interferon-gamma , Physiology , Islets of Langerhans , Cell Biology , MAP Kinase Signaling System , Nicotinamide Phosphoribosyltransferase , Physiology , Real-Time Polymerase Chain Reaction , Signal TransductionABSTRACT
<p><b>BACKGROUND</b>Suppressor of cytokine signaling (SOCS) proteins are inhibitors of cytokine signaling pathway involved in negative feedback loops. Although SOCS1 is an important intracellular suppressor of apoptosis in a variety of cell types, its role in cytokine-induced pancreatic β-cell apoptosis remains unclear. The present study investigated potential effects of SOCS1 on the cytokine-induced pancreatic β-cell apoptosis.</p><p><b>METHODS</b>After successfully transfected with SOCS1/pEGFP-C1 or pEGFP-C1 plasmids to overexpress SOCS1, RINm5F (rat insulinoma cell line) cells were exposed to cytokines, interferon (IFN)-γ alone, IFN-γ+interleukin (IL)-1β, IFN-β+IL-1β+tumor necrosis factor (TNF)-α respectively. Pancreatic β-cell apoptosis was assessed by using MTT, FACS, and caspase-3 activity assays. Protein phosphorylation of Janus kinase 2 (JAK2) and signal transducers and activators of transcription 1 (STAT1) were verified by Western blotting and mRNA expression of inducible nitric oxide synthase (iNOS), NF-κB and Fas were analyzed by RT-PCR.</p><p><b>RESULTS</b>Overexpression of SOCS1 in RINm5F cells was shown to attenuate IFN-γ alone, IFN-γ+IL-1β and IFN-γ+TNF-α+IL-1β mediated apoptosis. Phosphorylation of JAK2 and STAT1 significantly decreased in RINm5F cells which overexpressed SOCS1 protein. Overexpression of SOCS1 significantly suppressed cytokine-induced iNOS mRNA levels.</p><p><b>CONCLUSION</b>Overexpression of SOCS1 protects pancreatic islets from cytokine-induced cell apoptosis via the JAK2/STAT1 pathway.</p>
Subject(s)
Animals , Rats , Apoptosis , Genetics , Blotting, Western , Cell Line , Cytokines , Pharmacology , Interferon-gamma , Pharmacology , Interleukin-1 , Pharmacology , Islets of Langerhans , Cell Biology , Janus Kinase 2 , Metabolism , Phosphorylation , Reverse Transcriptase Polymerase Chain Reaction , STAT1 Transcription Factor , Genetics , Metabolism , Signal Transduction , Suppressor of Cytokine Signaling 1 Protein , Suppressor of Cytokine Signaling Proteins , Genetics , Metabolism , Tumor Necrosis Factor-alpha , PharmacologyABSTRACT
<p><b>OBJECTIVE</b>To study the differential patterns of gene expression in skeletal muscle and adipose tissue between type 2 diabetes mellitus (T2DM) patients and healthy subjects using DNA microarray analysis.</p><p><b>METHODS</b>T2DM patiens were divided into female group, young male group and old male group. DNA microarray analysis and quantitative real-time PCR were carried out to analyze the relation between gene expressions and T2DM.</p><p><b>RESULTS</b>The mRNA expression of 298, 578, and 350 genes was changed in the skeletal muscle of diabetes mellitus patients compared with control subjects. The 1320, 1143, and 2847 genes were modified in adipose tissue of the three groups. Among the genes surveyed, the change of 25 and 39 gene transcripts in skeletal muscle and adipose tissue was > or = 2 folds. These differentially expressed genes were classified into 15 categories according to their functions.</p><p><b>CONCLUSION</b>New genes are found and T2DM can be prevented or cured.</p>