Role of the pleckstrin homology domain of PLCγ1 in its interaction with the insulin receptor
Year: 2003
Type: article
Abstract: A thiol-reactive membrane-associated protein (TRAP) binds covalently to the cytoplasmic domain of the human insulin receptor (IR) beta-subunit when cells are treated with the homobifunctional cross-linker reagent 1,6-bismaleimidohexane. Here, TRAP was found to be phospholipase C gamma1 (PLCgamma1) by mass spectrometry analysis. PLCgamma1 associated with the IR both in cultured cell lines and in a primary culture of rat hepatocytes. Insulin increased PLCgamma1 tyrosine phosphorylation at Tyr-783 and its colocalization with the IR in punctated structures enriched in cortical actin at the dorsal plasma membrane. This association was found to be independent of PLCgamma1 Src homology 2 domains, and instead required the pleckstrin homology (PH)-EF-hand domain. Expression of the PH-EF construct blocked endogenous PLCgamma1 binding to the IR and inhibited insulin-dependent phosphorylation of mitogen-activated protein kinase (MAPK), but not AKT. Silencing PLCgamma1 expression using small interfering RNA markedly reduced insulin-dependent MAPK regulation in HepG2 cells. Conversely, reconstitution of PLCgamma1 in PLCgamma1-/- fibroblasts improved MAPK activation by insulin. Our results show that PLCgamma1 is a thiol-reactive protein whose association with the IR could contribute to the activation of MAPK signaling by insulin.
Source: The Journal of Cell Biology
Authors: Yong-Kook Kwon, Hyeung-Jin Jang, Sutapa Kole, Hua-Jun He, Michel Bernier
Institutions: National Institutes of Health, National Institute on Aging
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2063030664