title: IGF-I stimulates CCN5/WISP2 gene expression in pancreatic β-cells, which promotes cell proliferation and survival against streptozotocin.
abstract: IGF-I is normally produced from hepatocytes and other sources, stimulates protein synthesis, cell survival, and proliferation through receptor-mediated activation of phosphatidylinositol 3-kinase and MAPK, and targets specific molecules within the pancreatic islet cells. The current study was designed to identify novel targets that may mediate its pro-islet actions. Whole-genome cDNA microarray analysis in IGF-I-overexpressing islets identified 82 genes specifically up- or down-regulated. Prominent among them was CCN5/WISP2 whose expression was increased 3- and 2-fold at the mRNA and protein levels. Dual-labeled immunofluorescence revealed that CCN5 expression was low in the β-cells of wild-type islets but was significantly induced in response to IGF-I overexpression. In vitro treatment of mouse islets with IGF-I increased both CCN5 mRNA and protein levels significantly. To define the role of CCN5 in islet cell biology, we stably overexpressed its cDNA in insulinoma MIN6 cells and detected a 2-fold increase in the proliferation of MIN6-CCN5 compared with that in control cells, which correlated with significant elevations in the levels of cyclin D1 and the phosphorylation of Akt and Erk2. Moreover, MIN6-CCN5 cells were found to be resistant to streptozotocin-induced cell death. Using confocal microscopy and subcellular fractionation, we found that overexpressed CCN5 exhibited cytoplasmic accumulation upon stimulation by high glucose. Our results indicate that CCN5, which is minimally expressed in islet β-cells, is strongly and directly induced by IGF-I. CCN5 overexpression stimulates the proliferation of insulinoma cells, activates Akt kinase, and inhibits streptozotocin-induced apoptosis, suggesting that increased CCN5 expression contributes to IGF-I-stimulated islet cell growth and/or survival.
authors.affiliation: Fraser Laboratories for Diabetes Research (S.C., C.B.S., Q.L., Y.J.G., J.-L.L.), Department of Medicine (M.F.), McGill University Health Centre, Montreal, Quebec, Canada H3A 1A1; Shanghai Institute of Endocrine and Metabolic Diseases (X.W., G.N.) and Shanghai Clinical Center for Endocrine and Metabolic Diseases, Rui Jin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China; and Montreal Diabetes Research Centre (J.-L.L.), Montreal, Quebec, Canada H1W 4A4.
authors.forename: Subrata
authors.initials: S
authors.lastname: Chowdhury
authors.forename: Xiao
authors.initials: X
authors.lastname: Wang
authors.forename: Coimbatore B
authors.initials: CB
authors.lastname: Srikant
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
authors.forename: Min
authors.initials: M
authors.lastname: Fu
authors.forename: Ying Jia
authors.initials: YJ
authors.lastname: Gong
authors.forename: Guang
authors.initials: G
authors.lastname: Ning
authors.forename: Jun-Li
authors.initials: JL
authors.lastname: Liu
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D019938:Cyclin D1 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D004351:Drug Resistance; D020868:Gene Silencing; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013311:Streptozocin / Q000494:pharmacology*; D046509:Tissue Culture Techniques; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D000903:Antibiotics, Antineoplastic; C530105:Ccnd1 protein, mouse; C583557:IGF1 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D011994:Recombinant Proteins; C539089:WISP-2 protein, mouse; C519530:insulin-like growth factor-1, mouse; D019938:Cyclin D1; D013311:Streptozocin; D007334:Insulin-Like Growth Factor I