Differential regulation of ERK1/2 and mTORC1 through T1R1/T1R3 in MIN6 cells

Eric M. Wauson, Marcy L. Guerra, Julia Dyachok, Kathleen McGlynn, Jennifer Giles, Elliott M. Ross, Melanie H. Cobb

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

The MAPKs ERK1/2 respond to nutrients and other insulin secretagogues in pancreatic β cells and mediate nutrient-dependent insulin gene transcription. Nutrients also stimulate the mechanistic target of rapamycin complex 1 (mTORC1) to regulate protein synthesis. We showed previously that activation of both ERK1/2 and mTORC1 in the MIN6 pancreatic β cell-derived line by extracellular amino acids (AAs) is at least in part mediated by the heterodimeric T1R1/T1R3, a G protein-coupled receptor. We show here that AAs differentially activate these two signaling pathways in MIN6 cells. Pretreatment with pertussis toxin did not prevent the activation of either ERK1/2 or mTORC1 by AAs, indicating that Gi is not central to either pathway. Although glucagonlike peptide 1, an agonist for a Gs-coupled receptor, activated ERK1/2 well and mTORC1 to a small extent, AAs had no effect on cytosolic cAMP accumulation Ca2 entry is required for ERK1/2 activation by AAs but is dispensable for AA activation of mTORC1. Pretreatment with UBO-QIC, a selective Gq inhibitor, reduced the activation of ERK1/2 but had little effect on the activation of mTORC1 by AAs, suggesting a differential requirement for Gq. Inhibition of G12/13 by the overexpression of the regulator of G protein signaling domain of p115-guanine nucleotide exchange factor had no effect on mTORC1 activation by AAs, suggesting that these G proteins are also not involved. We conclude that AAs regulate ERK1/2 and mTORC1 through distinct signaling pathways.

Original languageEnglish (US)
Pages (from-to)1114-1122
Number of pages9
JournalMolecular Endocrinology
Volume29
Issue number8
DOIs
StatePublished - Jul 31 2015

ASJC Scopus subject areas

  • Molecular Biology
  • Endocrinology

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