Apivotalpointincellularresourceallocationisthepointatwhichglycolyticintermediatesare partitionedtolipidbiosynthesisversusrespiration.Forexample,hyperlipidemiaoccurswhen cellsfavorlipidbiogenesisandisamajorriskfactorforcardiovasculardisease(CVD)including coronaryheartdisease,heartattackandstroke,thenumberonecausesofdeathintheUnited States.PASkinaseisaserine-threonineproteinkinasethatisakeyregulatorofthispivotal pointinglucoseallocation.PASkinase-deficientmice(PASK-/-)placedonahigh-fatdietora high-fathigh-sugardietareresistanttolivertriglycerideaccumulationanddisplayincreased wholeanimalaswellascellularrespirationrateswhencomparedtotheirwildtypelittermates. Livertriglycerideaccumulationandalteredmetabolicratearetwoprimaryriskfactorsinthe developmentofCVDaswellasrelateddiseasessuchastypeIIdiabetes.Wehaverecently identifiedtwoPASkinasesubstratesthatmayexplainitsregulationofthispivotalpointin metabolism,upstreamstimulatoryfactor1(USF1)andAtaxin-2.OurhypothesisisthatPAS kinaseregulatesthepivotalpointofpartitioningglucosetolipidversusrespiratorypathways throughphosphorylationofitssubstratesUSF1andAtaxin-2.USF1isatranscriptionfactorthat directlyregulatesfattyacidsynthaseandhumanmutationsinUSF1areassociatedwithfamilial hypercholesterolemia.PASkinasephosphorylatesandinhibitsUSF1inyeast.This phosphorylationleadstodecreasedrespirationandincreasedlipidbiosynthesis.Ataxin-2,on theotherhand,associateswithandsequestersmRNAandproteinstostressgranules, regulatingcellularmetabolismthroughtheirinhibition.PASkinase-dependentphosphorylation ofAtaxin-2activatestheproteinbyincreasingitslocalizationtostressgranulesinyeast.The focusofthisproposalistofurthercharacterizetheeffectsofPASkinase-dependent phosphorylationonthefunctionofUSF1andAtaxin-2inyeastandmammaliansystems.Our longtermgoalistoincreaseourunderstandingoftheregulationofcentralmetabolismwhile trainingundergraduatesinscientificresearch,therebyidentifyingnoveltargetsforthetreatment ofmetabolicdisease.Throughoutthisproposalwewillusethegeneticandbiochemicaltoolsof yeasttoinvestigatediseasesforwhichmostundergraduateshaveapersonalconnectionto, namelyhyperlipidemiaanddiabetes.
Yeast is a perfect model organism in which to train undergraduates in biomedical research due to the ease of efficient methods and the application to human disease. The objective of this proposal is to use the biochemical and genetic tools of S. cerevisiae to characterize molecular pathways involved in the decision to partition glucose to respiration versus lipid biosynthesis, and to validate these findings in mammalian systems. Regulation of this pivotal metabolic node is likely to be key in the development and/or progression of metabolic diseases such as hyperlipidemia, diabetes, cancer and neurodegenerative disease.
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| DeMille, Desiree; Badal, Bryan D; Evans, J Brady et al. (2015) PAS kinase is activated by direct SNF1-dependent phosphorylation and mediates inhibition of TORC1 through the phosphorylation and activation of Pbp1. Mol Biol Cell 26:569-82 |
| DeMille, Desiree; Bikman, Benjamin T; Mathis, Andrew D et al. (2014) A comprehensive protein-protein interactome for yeast PAS kinase 1 reveals direct inhibition of respiration through the phosphorylation of Cbf1. Mol Biol Cell 25:2199-215 |
| DeMille, Desiree; Grose, Julianne H (2013) PAS kinase: a nutrient sensing regulator of glucose homeostasis. IUBMB Life 65:921-9 |
