Abstract：bjective: To investigate the mechanism of Exendin-4 regulating proliferation of pancreatic β cell line INS-1. Methods: After stimulation of Exendin-4,the proliferation rate of INS-1 cells was detected by EdU method. The expression of Wnt5a gene was detected by realtime semi-quantitative PCR and Westernblotting.The proliferation rate of INS-1 cells was evaluated by EdU method after Wnt5a gene was silenced by siRNA. Cocultured with Exendin-4 and recombinant Wnt5a protein, the proliferation rate was observed by EdU labelling method. Results: The baseline expression of Wnt5a in INS-1 reached a considerably high level, and Exendin-4 significantly decreased the expression of Wnt5a gene in INS-1 cells at both mRNA and protein level. Transient transfection of siRNA-Wnt5a into INS-1 cells decreased the proliferation rate of cells. Recombinant Wnt5a protein antagonized the pro-proliferative effect of Exendin-4 on INS-1 cells in a dose-dependent manner. Conclusion: Exendin-4 promotes INS-1 proliferation via downregulating the expression of Wnt5a gene.
［1］Holst JJ.Treatment of type 2 diabetes mellitus with agonists of the GLP1 receptor or DPPIV inhibitors\[J\].Expert Opin Emerg Drugs,2004,9(1):155-166.［2］Gordon MD, Nusse R. Wnt signaling: multiple pathways, multiple receptors, and multiple transcription factors\[J\].J Biol Chem,2006,281(32):22429-22433.［3］Moon RT,Kohn AD,De Ferrari GV,et al.WNT and βcatenin signalling: diseases and therapies\[J\]. Nat Rev Genet,2004,5(9):691-701.［4］Heller C, Kühn MC, MüldersOpgenoorth B,et al.Exendin4 upregulates the expression of Wnt4, a novel regulator of pancreatic βcell proliferation\[J\].Am J Physiol Endocrinol Metab,2011,301(5):E864-872.［5］Wang Q, Li L, Xu E,et al.Glucagonlike peptide1 regulates proliferation and apoptosis via activation of protein kinase B in pancreatic INS1 β cells\[J\].Diabetologia, 2004,47(3):478-487.［6］Liu Z,Habener JF.Glucagonlike peptide1 activation of TCF7L2dependent Wnt signaling enhances pancreatic β cell proliferation\[J\].J Biol Chem,2008,283(13): 8723-8735.［7］Rulifson IC,Karnik SK,Heiser PW,et al.Wnt signaling regulates pancreatic β cell proliferation\[J\].Proc Natl Acad Sci U S A,2007,104(15):6247-6252.［8］Murtaugh LC.The what, where, when and how of Wnt/βcatenin signaling in pancreas development\[J\].Organogenesis,2008,4(2):81-86.［9］Heller RS,Klein T,Ling Z,et al.Expression of Wnt,Frizzled,sFRP,and DKK genes in adult human pancreas\[J\].Gene Expr,2003,11(3/4):141-147.［10］Kühl M.Noncanonical Wnt signaling in Xenopus:regulation of axis formation and gastrulation\[J\].Semin Cell Dev Biol,2002,13(3):243-249.［11］Kim HJ,Schleiffarth JR,Jessurun J,et al.Wnt5 signaling in vertebrate pancreas development\[J\].BMC Biol,2005,3:23.［12］Stratton R,Rajkumar V,Ponticos M,et al.Prostacyclin derivatives prevent the fibrotic response to TGFβ by inhibiting the Ras/MEK/ERK pathway\[J\].The FASEB J,2002,16(14):1949-1951.［13］Ripka S, Knig A, Buchholz M,et al.WNT5Atarget of CUTL1 and potent modulator of tumor cell migration and invasion in pancreatic cancer\[J\].Carcinogenesis, 2007,28(6):1178-1187.［14］Schinner S,Ulgen F,Papewalis C, et al. Regulation of insulin secretion, glucokinase gene transcription and beta cell proliferation by adipocytederived Wnt signalling molecules\[J\].Diabetologia,2008,51(1):147-154.［15］Liang H,Chen Q,Coles AH,et al.Wnt5a inhibits B cell proliferation and functions as a tumor suppressor in hematopoietic tissue\[J\].Cancer Cell,2003,4(5):349-360.［16］Topol L,Jiang X,Choi H,et al.Wnt5a inhibits the canonical Wnt pathway by promoting GSK3independent βcatenin degradation\[J\].J Cell Biol,2003,162(5):899-908.
2018, Vol. 28 
