title: Differential Regulation of ERK1/2 and mTORC1 Through T1R1/T1R3 in MIN6 Cells.
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 G(I) is not central to either pathway. Although glucagon-like peptide 1, an agonist for a G(s-)coupled receptor, activated ERK1/2 well and mTORC1 to a small extent, AAs had no effect on cytosolic cAMP accumulation. Ca(2+) entry is required for ERK1/2 activation by AAs but is dispensable for AA activation of mTORC1. Pretreatment with UBO-QIC, a selective G(q) inhibitor, reduced the activation of ERK1/2 but had little effect on the activation of mTORC1 by AAs, suggesting a differential requirement for G(q). Inhibition of G(12/13) by the overexpression of the regulator of G protein signaling domain of p115 ρ-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.
authors.affiliation: Department of Pharmacology (E.M.W., M.L.G., J.D., K.M., E.M.R., M.H.C.) and the Green Center for Systems Biology (J.D., E.M.R.), University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041; and Department of Physiology and Pharmacology (E.M.W., J.G.), Des Moines University, Des Moines, Iowa 50312.
authors.forename: Eric M
authors.initials: EM
authors.lastname: Wauson
authors.affiliation: Department of Pharmacology (E.M.W., M.L.G., J.D., K.M., E.M.R., M.H.C.) and the Green Center for Systems Biology (J.D., E.M.R.), University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041; and Department of Physiology and Pharmacology (E.M.W., J.G.), Des Moines University, Des Moines, Iowa 50312.
authors.forename: Marcy L
authors.initials: ML
authors.lastname: Guerra
authors.affiliation: Department of Pharmacology (E.M.W., M.L.G., J.D., K.M., E.M.R., M.H.C.) and the Green Center for Systems Biology (J.D., E.M.R.), University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041; and Department of Physiology and Pharmacology (E.M.W., J.G.), Des Moines University, Des Moines, Iowa 50312.
authors.forename: Julia
authors.initials: J
authors.lastname: Dyachok
authors.affiliation: Department of Pharmacology (E.M.W., M.L.G., J.D., K.M., E.M.R., M.H.C.) and the Green Center for Systems Biology (J.D., E.M.R.), University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041; and Department of Physiology and Pharmacology (E.M.W., J.G.), Des Moines University, Des Moines, Iowa 50312.
authors.forename: Kathleen
authors.initials: K
authors.lastname: McGlynn
authors.affiliation: Department of Pharmacology (E.M.W., M.L.G., J.D., K.M., E.M.R., M.H.C.) and the Green Center for Systems Biology (J.D., E.M.R.), University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041; and Department of Physiology and Pharmacology (E.M.W., J.G.), Des Moines University, Des Moines, Iowa 50312.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Giles
authors.affiliation: Department of Pharmacology (E.M.W., M.L.G., J.D., K.M., E.M.R., M.H.C.) and the Green Center for Systems Biology (J.D., E.M.R.), University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041; and Department of Physiology and Pharmacology (E.M.W., J.G.), Des Moines University, Des Moines, Iowa 50312.
authors.forename: Elliott M
authors.initials: EM
authors.lastname: Ross
authors.affiliation: Department of Pharmacology (E.M.W., M.L.G., J.D., K.M., E.M.R., M.H.C.) and the Green Center for Systems Biology (J.D., E.M.R.), University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041; and Department of Physiology and Pharmacology (E.M.W., J.G.), Des Moines University, Des Moines, Iowa 50312.
authors.forename: Melanie H
authors.initials: MH
authors.lastname: Cobb
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D050417:Insulin-Secreting Cells / Q000166:cytology; D008247:Lysosomes / Q000378:metabolism; D000076222:Mechanistic Target of Rapamycin Complex 1; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D055503:Protein Multimerization; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D046912:Multiprotein Complexes; D043562:Receptors, G-Protein-Coupled; C431926:taste receptors, type 1; D000242:Cyclic AMP; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; C535150:MAPK1 protein, human; C535148:Mapk1 protein, mouse; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D002118:Calcium