The incidence of obesity has increased dramatically over the last fifty years. Over half of all Americans are over-weight and over one third are classified as clinically obese. The health ramifications of this epidemic of obesity are seen in the concomitant increase in the incidence of type 2 diabetes. An estimated 29 million Americans have diabetes with 95% of those being type 2. Metformin, the most commonly prescribed therapeutic used to treat the early stages of type 2 diabetes targets the AMP-activated protein kinase (AMPK). Therefore, defining the functions and regulation of AMPK is of great significance to human health. This proposal uses baker's yeast as its model system to study the regulation of the yeast AMPK. In both yeast and human cells, the overall structure of AMPK and the modes of regulation are highly conserved. The speed and synergy of genetic and biochemical studies in yeast make this an ideal system to dissect the regulation of AMPK and apply the new knowledge to human biology. We have found that yeast AMPK regulates glucose transport by controlling which glucose transporters are maintained on the plasma membrane. We will investigate the molecular mechanism by which yeast AMPK controls the localization, function and expression of glucose transporters. In addition we have discovered a novel mechanism by which the glucose analog, 2- deoxyglucose, inhibits glucose metabolism. Yeast and cancer cells share a metabolic strategy called aerobic glycolysis that makes them extra sensitive to 2-deoxyglucose. We will use genetic, biochemical and genomic technologies to define the mechanisms underlying the toxicity and acquired resistance to this compound. Last, we have identified Snf1 serine-214 phosphorylation as a novel mechanism for the down-regulation of Snf1 signaling. We will employ a genetic screen to identify the kinase responsible for the modification.

Public Health Relevance

This project studies the function and regulation of an enzyme called AMP-activated protein kinase. This enzyme is a key metabolic regulator in humans and is the target of the most widely prescribed drug used to treat type 2 diabetes. We take advantage of the speed and facility of genetic and biochemical studies in a model organism in order to increase our understanding of this medically important enzyme.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Cellular Signaling and Regulatory Systems Study Section (CSRS)
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Hoodbhoy, Tanya
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University of Pittsburgh
Schools of Medicine
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Offley, Sarah R; Schmidt, Martin C (2018) Protein phosphatases of Saccharomyces cerevisiae. Curr Genet :
McCartney, Rhonda R; Garnar-Wortzel, Leopold; Chandrashekarappa, Dakshayini G et al. (2016) Activation and inhibition of Snf1 kinase activity by phosphorylation within the activation loop. Biochim Biophys Acta 1864:1518-28
Chandrashekarappa, Dakshayini G; McCartney, Rhonda R; O'Donnell, Allyson F et al. (2016) The ? subunit of yeast AMP-activated protein kinase directs substrate specificity in response to alkaline stress. Cell Signal 28:1881-1893
O'Donnell, Allyson F; McCartney, Rhonda R; Chandrashekarappa, Dakshayini G et al. (2015) 2-Deoxyglucose impairs Saccharomyces cerevisiae growth by stimulating Snf1-regulated and ?-arrestin-mediated trafficking of hexose transporters 1 and 3. Mol Cell Biol 35:939-55
McCartney, Rhonda R; Chandrashekarappa, Dakshayini G; Zhang, Bob B et al. (2014) Genetic analysis of resistance and sensitivity to 2-deoxyglucose in Saccharomyces cerevisiae. Genetics 198:635-46
Schmidt, Martin C (2013) Signaling crosstalk: integrating nutrient availability and sex. Sci Signal 6:pe28
Chandrashekarappa, Dakshayini G; McCartney, Rhonda R; Schmidt, Martin C (2013) Ligand binding to the AMP-activated protein kinase active site mediates protection of the activation loop from dephosphorylation. J Biol Chem 288:89-98
Mayer, Faith V; Heath, Richard; Underwood, Elizabeth et al. (2011) ADP regulates SNF1, the Saccharomyces cerevisiae homolog of AMP-activated protein kinase. Cell Metab 14:707-14
Chandrashekarappa, Dakshayini G; McCartney, Rhonda R; Schmidt, Martin C (2011) Subunit and domain requirements for adenylate-mediated protection of Snf1 kinase activation loop from dephosphorylation. J Biol Chem 286:44532-41
Zhang, Yuxun; McCartney, Rhonda R; Chandrashekarappa, Dakshayini G et al. (2011) Reg1 protein regulates phosphorylation of all three Snf1 isoforms but preferentially associates with the Gal83 isoform. Eukaryot Cell 10:1628-36

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