PLC-γ1 Enzyme Activity Is Required for Insulin-Induced DNA Synthesis

• Published in: Endocrinology (Philadelphia) Vol. 143; no. 2; pp. 655 - 664
• Main Authors: Eichhorn, Jens, Kayali, Ayse G, Resor, Laura, Austin, Darrell A, Rose, David W, Webster, Nicholas J. G
• Format: Journal Article
• Language: English
• Published: Endocrine Society 01.02.2002
• ISSN: 0013-7227; 1945-7170
• DOI: 10.1210/endo.143.2.8621

Previously, we had shown that inhibition of PLC activity impaired the ability of insulin to activate ERK in 3T3-L1 adipocytes. In this study, we confirmed that the insulin receptor and PLC-γ1 are physically associated in hIRcB fibroblasts, insulin stimulates PLC-γ1 enzyme activity, and inhibition of PLC activity impairs activation of ERK. We subsequently investigated whether PLC-γ1 is required for insulin-stimulated mitogenesis. First, inhibition of PLC activity using U73122 impairs the ability of insulin to stimulate DNA synthesis. Second, disruption of the interaction of the insulin receptor with PLC-γ1 by microinjection of SH2 domains derived from PLC-γ1 or Grb2 but not Shc similarly blocks insulin-induced DNA synthesis. Third, microinjection of neutralizing antibodies to PLC-γ1 blocks DNA synthesis, but nonneutralizing antibodies do not. The blockade in all three cases is rescued by synthetic diacylglycerols but not by inositol-1,4,5-trisphosphate, indicating a requirement for PLC enzyme activity. These experimental data point to a requirement for PLC-γ1 in insulin-stimulated mitogenesis in hIRcB cells.