Snf1 protein kinase of Saccharomyces cerevisiae is a member of the highly conserved Snf1/AMP-activated protein kinase (AMPK) family, which plays a central role in responses to metabolic stress. In humans, AMPK regulates glucose and lipid metabolism to maintain cellular energy balance and has been implicated in the pathogenesis of human disease, including diabetes, obesity, cancer, and hereditary heart disease. In yeast, the Snfl pathway has a primary role in the response to nutrient stress. We propose to continue our functional analysis of the Snfl/AMPK pathway in the yeast system, which offers the advantages of powerful genetics and has informed our understanding of the human pathway. We propose genetic and biochemical studies to address the roles of the Snf1-activating kinases (Pak1, Tos3, and Elm1) and the Reg1-Glc7 protein phosphatase 1 in regulating Snft catalytic activity. The proposed work on the noncatalytic subunits of Snf1 protein kinase, Snf4 and Gal83, will elucidate their functions in regulating the activity and localization of the protein kinase. Snf4 comprises domains that are involved in AMP binding in AMPK. The Gal83 beta subunit controls the glucose-regulated nuclear localization of the kinase. Studies of the interconnections between the Snf1 pathway and the highly conserved PKA, Yak1, and CK2 pathways will provide insight into the role of the Snf1/AMPK pathway in cellular regulation. Finally, we propose to take advantage of the yeast system for genetic analysis of mammalian LKB1, which is a major activating kinase for AMPK and AMPK-related kinases and has important roles in suppressing tumorigenesis. Mutations in LKB1 in humans cause hereditary Peutz-Jeghers cancer syndrome. LKB1 alone, or in the LKB1-STRAD- MO25 complex, functions as a Snf1-activating kinase in yeast, thereby allowing selection of mutations that improve its activating function. The proposed studies will elucidate regulatory mechanisms that control the AMPK pathway, which is important in type 2 diabetes, obesity, cancer, and hereditary heart disease. These studies will provide insight into human disease and lead to development of drugs to activate AMPK for treatment. The proposed work on mammalian LKB1, a tumor suppressor that activates AMPK, will provide clues for the design of activating drugs. ? ? ?

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Cellular Signaling and Dynamics Study Section (CSD)
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Anderson, Richard A
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Columbia University (N.Y.)
Internal Medicine/Medicine
Schools of Medicine
New York
United States
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Ruiz, Amparo; Xu, Xinjing; Carlson, Marian (2013) Ptc1 protein phosphatase 2C contributes to glucose regulation of SNF1/AMP-activated protein kinase (AMPK) in Saccharomyces cerevisiae. J Biol Chem 288:31052-8
Ruiz, Amparo; Liu, Yang; Xu, Xinjing et al. (2012) Heterotrimer-independent regulation of activation-loop phosphorylation of Snf1 protein kinase involves two protein phosphatases. Proc Natl Acad Sci U S A 109:8652-7
Momcilovic, Milica; Carlson, Marian (2011) Alterations at dispersed sites cause phosphorylation and activation of SNF1 protein kinase during growth on high glucose. J Biol Chem 286:23544-51
Ruiz, Amparo; Xu, Xinjing; Carlson, Marian (2011) Roles of two protein phosphatases, Reg1-Glc7 and Sit4, and glycogen synthesis in regulation of SNF1 protein kinase. Proc Natl Acad Sci U S A 108:6349-54
Liu, Yang; Xu, Xinjing; Carlson, Marian (2011) Interaction of SNF1 protein kinase with its activating kinase Sak1. Eukaryot Cell 10:313-9
Amodeo, Gabriele A; Momcilovic, Milica; Carlson, Marian et al. (2010) Biochemical and functional studies on the regulation of the Saccharomyces cerevisiae AMPK homolog SNF1. Biochem Biophys Res Commun 397:197-201
Momcilovic, Milica; Iram, Surtaj H; Liu, Yang et al. (2008) Roles of the glycogen-binding domain and Snf4 in glucose inhibition of SNF1 protein kinase. J Biol Chem 283:19521-9
Hedbacker, Kristina; Carlson, Marian (2008) SNF1/AMPK pathways in yeast. Front Biosci 13:2408-20
Rudolph, Michael J; Amodeo, Gabriele A; Iram, Surtaj H et al. (2007) Structure of the Bateman2 domain of yeast Snf4: dimeric association and relevance for AMP binding. Structure 15:65-74
Hong, Seung-Pyo; Carlson, Marian (2007) Regulation of snf1 protein kinase in response to environmental stress. J Biol Chem 282:16838-45

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