Bifulco G, Di Carlo C, Caruso M, Oriente F, Di Spiezio Sardo A, Formisano P, Beguinot F, Nappi C. Glucose regulates insulin mitogenic effect by modulating SHP-2 activation and localization in JAr cells.
J Biol Chem 2002;
277:24306-14. [PMID:
11983706 DOI:
10.1074/jbc.m202962200]
[Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The glucose effect on cell growth has been investigated in the JAr human choriocarcinoma cells. When JAr cells were cultured in the presence of 6 mm glucose (LG), proliferation and thymidine incorporation were induced by serum, epidermal growth factor, and insulin-like growth factor 1 but not by insulin. In contrast, at 25 mm glucose (HG), proliferation and thymidine incorporation were stimulated by insulin, serum, epidermal growth factor, and insulin-like growth factor 1 to a comparable extent, whereas basal levels were 25% lower than those in LG. HG culturing also enhanced insulin-stimulated insulin receptor and insulin receptor substrate 1 (IRS1) tyrosine phosphorylations while decreasing basal phosphorylations. These actions of glucose were accompanied by an increase in cellular tyrosine phosphatase activity. The activity of SHP-2 in HG-treated JAr cells was 400% of that measured in LG-treated cells. SHP-2 co-precipitation with IRS1 was also increased in HG-treated cells. SHP-2 was mainly cytosolic in LG-treated cells. However, HG culturing largely redistributed SHP-2 to the internal membrane compartment, where tyrosine-phosphorylated IRS1 predominantly localizes. Further exposure to insulin rescued SHP-2 cytosolic localization, thereby preventing its interaction with IRS1. Antisense inhibition of SHP-2 reverted the effect of HG on basal and insulin-stimulated insulin receptor and IRS1 phosphorylation as well as that on thymidine incorporation. Thus, in JAr cells, glucose modulates insulin mitogenic action by modulating SHP-2 activity and intracellular localization.
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