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Ghrelin modulates the downstream molecules of insulin signaling in hepatoma cells.

Research paper by Masahiro M Murata, Yasuhiko Y Okimura, Keiji K Iida, Michihiro M Matsumoto, Hideaki H Sowa, Hidesuke H Kaji, Masayasu M Kojima, Kenji K Kangawa, Kazuo K Chihara

Indexed on: 29 Nov '01Published on: 29 Nov '01Published in: Journal of Biological Chemistry



Abstract

Ghrelin was identified in the stomach as an endogenous ligand specific for the growth hormone secretagogue receptor (GHS-R). GHS-R is found in various tissues, but its function is unknown. Here we show that GHS-R is found in hepatoma cells. Exposure of these cells to ghrelin caused up-regulation of several insulin-induced activities including tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1), association of the adapter molecule growth factor receptor-bound protein 2 with IRS-1, mitogen-activated protein kinase activity, and cell proliferation. Unlike insulin, ghrelin inhibited Akt kinase activity as well as up-regulated gluconeogenesis. These findings raise the possibility that ghrelin modulates insulin activities in humans.