Duringthedevelopmentofheartfailurecardiacfuelmetabolismswitchesfrompredominantlyfattyacidoxidation (FAO)toincreasedrelianceonglucose,especiallyglycolysis.Thismetabolicremodelingisgenerallyrecognized and considered ultimately maladaptive for sustaining myocardial energetics and function. The mechanisms responsiblefortheswitcharepoorlyunderstoodbutappeartobecoupledwithimpairedmitochondrialfunction. Downregulations of multiple transcriptional mechanisms, such as PPARa? or PGC-1a?, for FAO have been identified in heart failure. Reduced FAO could release the inhibition of glucose use through Randle cycle and thuspromotemyocardialglucoseutilization.However,thishypothesisdoesnotexplainwhyreducedFAOleads to predominantly glycolysis uncoupled with glucose oxidation, a phenomenon similar to Warburg effect. In additiontodecreasedFAO,multipleaspectsofmitochondrialfunction,inparticular,oxidativephosphorylation, oxidativestress,andredoxbalance,arealsoalteredinheartswithpathologicalhypertrophy.Theseobservations raise an intriguing possibility that increased glycolysis is driven by mitochondrial dysfunction although the molecularmediator(s)intheswitchareelusive.Recently,wefoundthattheexpressionofmitochondrialATPase inhibitorfactor1(ATPIF1)wasincreasedinrodentheartsorcardiomyocytes(CMs)withpathologicalhypertrophy. UpregulationofATPIF1innon-cardiomyocyteshasbeenshowntoincreaseglycolysis,totriggermitochondrial hyperpolarization and increase the production of mitochondrial reactive oxygen species (mtROS). In our preliminary study, ATPIF1 overexpression also shifted energy metabolism from mitochondrial oxidation to glycolysisinCMs.Therefore,weaskedwhetherandhowATPIF1connectsmitochondrialfunctionandglycolysis intheheartundergoingpathologicalhypertrophy.TheATPIF1iswellconservedfromyeasttohuman,anditis knowntoinhibitthereversedoperationofFoF1-ATPaseinComplexV(normallyfunctionsasATPsynthase)to hydrolyzeATPandthusmaintaintheprotongradientduringreducedmembranepotential,suchasischemia.The consequence ofATPIF1 upregulation in the non-ischemic heart is unknown. In the proposed study, we will determinetheinteractionofATPIF1withComplexVundernormalandstressconditionsandtestthehypothesis that increased ATPIF1 inhibits ATP synthase and triggers the metabolic switch to glycolysis via stimulationofHIF1a?signalingduringpathologicalhypertrophy.Wehavegeneratedpreliminarydataand research tools for the following three specific aims: 1) To test the hypothesis that up-regulation ofATPIF1 increasesmyocardialglycolysisthroughenhancingtheHIF1?signaling.2)Todeterminethemolecular interaction of ATPIF1 and FoF1-ATPase and changes of mitochondrial protein interactome under physiological and pathological conditions using quantitative Protein Interaction Reporter (PIR) technology. 3) To determine the in vivo role ofATPIF1 in the metabolic reprogramming and cardiac responsetostress.

Public Health Relevance

The proposed study will determine the molecular mechanisms dictating the switch of oxidative mechanism to glycolysis in pathological cardiac hypertrophy. We will first, test the hypothesis that mitochondrial dysfunction drives the metabolic switch and second, evaluate the role of a mitochondrial protein ATPIF1 as the mediator of the switch.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL142628-02
Application #
9732624
Study Section
Myocardial Ischemia and Metabolism Study Section (MIM)
Program Officer
Wong, Renee P
Project Start
2018-07-01
Project End
2022-04-30
Budget Start
2019-05-01
Budget End
2020-04-30
Support Year
2
Fiscal Year
2019
Total Cost
Indirect Cost
Name
University of Washington
Department
Anesthesiology
Type
Schools of Medicine
DUNS #
605799469
City
Seattle
State
WA
Country
United States
Zip Code
98195