Author:
Álvarez Carlos J P,Lodeiro María,Theodoropoulou Marily,Camiña Jesús P,Casanueva Felipe F,Pazos Yolanda
Abstract
Obestatin was identified as a gut peptide encoded by the ghrelin gene that interacts with the G protein-coupled receptor, GPR39. In this work, a sequential analysis of its transmembrane signalling pathway has been undertaken to characterize the intracellular mechanisms responsible for Akt activation. The results show that Akt activation requires the phosphorylation of T308 in the A-loop by the phosphoinositide-dependent kinase 1 (PDK1) and S473 within the HM by the mammalian target of rapamycin (mTOR) kinase complex 2 (mTORC2: Rictor, mLST8, mSin1, mTOR kinase) with participation neither of Gi/o-protein nor Gβγ dimers. Obestatin induces the association of GPR39/β-arrestin 1/Src signalling complex resulting in the transactivation of the epidermal growth factor receptor (EGFR) and downstream Akt signalling. Upon administration of obestatin, phosphorylation of mTOR (S2448) and p70S6K1 (T389) rise with a time course that parallels that of Akt activation. Based on the experimental data obtained, a signalling pathway involving a β-arrestin 1 scaffolding complex and EGFR to activate Akt signalling is proposed.
Subject
Cancer Research,Endocrinology,Oncology,Endocrinology, Diabetes and Metabolism
Cited by
41 articles.
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