The goal of this project is to describe in molecular detail one limb of the insulin signal transduction system. Nearly all of the classical metabolic responses to insulin require activation of the phosphatidylinositol 3' OH kinase (PI-3 Kinase). Thus to understand insulin signalling, the identity of the effectors of the PI-3 Kinase relevant to insulin must be identified and characterized. This project focuses on an outflow from PI-3 kinase to the protein (Ser/Thr) kinase known as p70 S6 kinase. This enzyme appears to be critical to the insulin control of protein synthesis, in particular to the process of ribosomal biogenesis, a crucial component of the anabolic response to insulin. We showed previously that p70 is regulated by insulin through a complex multisite phosphorylation directed at several different domains involving Thr252, Ser394, Thr412 and others, and catalyzed by an array of PI-3 Kinase-regulated protein kinases situated upstream. The activity of the p7O S6 kinase is also regulated by the availability of amino acids through a novel signal transduction pathway, largely distinct from that controlled by insulin, but which converges with the pathway controlled by the mTOR kinase, the target of the immuno- suppressant drug, rapamycin. This novel amino and mTOR responsive pathway may utilize protein phosphatases to control cell function. We recently discovered one of the enzymes responsible for the insulin activation of p70 S6 kinase. This enzyme, called PDK1 is also one of the activators of the cAkt/PKB kinase. PDK1 must work in conjunction with other, as yet unidentified Ptd Ins (3,4,5)P3 activated kinases, in order to activate effectively both p70 and PKB. The goals of this project for the next period are to: 1) Isolate and characterize the other PI-3 kinase-regulated protein kinase necessary for activation of p70, the p70 Thr412 kinase; 2 ) Characterize the protein kinase active on p70 Ser394 in vivo, and the nature and significance of mTO- catalyzed phosphorylation of p70; 3) Characterize the protein phosphatases that act on p70 and their regulation by insulin, amino acids an mTOR; 4) Characterize the regulation, cellular itinerary and cellular targets of PDK1, an important multifunctional PI-3 kinase effector. These studies will clarify several of the major new signalling outflows of the insulin receptor, and will provide new insights into the regulation of protein synthesis. These results will have implications for the design of new pharmacologic interventions in diabetes mellitus and will have wide implications for the nutritional regulation of body protein turnover.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
3R37DK017776-24S1
Application #
6132855
Study Section
Metabolism Study Section (MET)
Program Officer
Silva, Corinne M
Project Start
1999-03-15
Project End
1999-12-31
Budget Start
1999-03-15
Budget End
1999-12-31
Support Year
24
Fiscal Year
1999
Total Cost
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02199
Dai, Ning; Ji, Fei; Wright, Jason et al. (2017) IGF2 mRNA binding protein-2 is a tumor promoter that drives cancer proliferation through its client mRNAs IGF2 and HMGA1. Elife 6:
Galan, Jacob A; Avruch, Joseph (2016) MST1/MST2 Protein Kinases: Regulation and Physiologic Roles. Biochemistry 55:5507-5519
Dai, Ning; Zhao, Liping; Wrighting, Diedra et al. (2015) IGF2BP2/IMP2-Deficient mice resist obesity through enhanced translation of Ucp1 mRNA and Other mRNAs encoding mitochondrial proteins. Cell Metab 21:609-21
Papageorgiou, Angela; Rapley, Joseph; Mesirov, Jill P et al. (2015) A genome-wide siRNA screen in mammalian cells for regulators of S6 phosphorylation. PLoS One 10:e0116096
Oshiro, Noriko; Rapley, Joseph; Avruch, Joseph (2014) Amino acids activate mammalian target of rapamycin (mTOR) complex 1 without changing Rag GTPase guanyl nucleotide charging. J Biol Chem 289:2658-74
Regué, Laura; Mou, Fan; Avruch, Joseph (2013) G protein-coupled receptors engage the mammalian Hippo pathway through F-actin: F-Actin, assembled in response to Galpha12/13 induced RhoA-GTP, promotes dephosphorylation and activation of the YAP oncogene. Bioessays 35:430-5
Dai, Ning; Christiansen, Jan; Nielsen, Finn C et al. (2013) mTOR complex 2 phosphorylates IMP1 cotranslationally to promote IGF2 production and the proliferation of mouse embryonic fibroblasts. Genes Dev 27:301-12
Wu, Hongtan; Xiao, Yubo; Zhang, Shihao et al. (2013) The Ets transcription factor GABP is a component of the hippo pathway essential for growth and antioxidant defense. Cell Rep 3:1663-77
Papageorgiou, Angela; Avruch, Joseph (2012) A genome-wide RNAi screen for polypeptides that alter rpS6 phosphorylation. Methods Mol Biol 821:187-214
Avruch, Joseph; Zhou, Dawang; Fitamant, Julien et al. (2012) Protein kinases of the Hippo pathway: regulation and substrates. Semin Cell Dev Biol 23:770-84

Showing the most recent 10 out of 57 publications