Background: Pulmonary hypertension (PH) is a deadly disease of the lung vasculature with a complex pathophysiology that remains largely undefined. My mentor?s laboratory established the microRNA-130/301 familyasamediatorofPHdevelopmentanddefinedaseparatemechanismbywhichiron-sulfur(Fe-S)cluster deficiencypromotesPH.Fe-Sclustersarebioinorganiccofactorsessentialtomitochondrialandcellularfunction. Frataxin(FXN)isamitochondrialproteincrucialtoFe-Sbiogenesis.LossofFXNduetoatrinucleotiderepeat mutationcausesFriedreich?sataxia(FRDA),adiseasecharacterizedbyneurologicdysfunctionandhypertrophic cardiomyopathy. Hypertrophic cardiomyopathy is often accompanied by PH, thought to be the result of left ventricularstiffeningratherthandirectdysfunctionofthepulmonaryvessels.However,Ihavefoundthathypoxia, a key trigger of PH, down-regulated FXN expression in pulmonary arterial endothelial cells. FXN was also decreased in the pulmonary vasculature of mice and humans with PH. Consequently, such FXN deficiency alteredendothelialmitochondrial,vasomotor,apoptoticindices,thusleadingtopreliminarydataregardingthe alterationofPHinvivo.Takentogether,theremaybeadirectroleforFXNinPH.Hypothesis:FXNdeficiency, inducedbyhypoxiaorgeneticmutation,disruptsendothelialmetabolismandfunctiontopromotePH.
SpecificAims :1)Determinewhetherhypoxicdown-regulationofFXNiscontrolledbymiR-130b.Ihave foundthattheFXNtranscriptcontainsapossiblebindingsiteforthePH-relevantmiR-130b.Bygain-andloss- of-functionmethodsinpulmonaryarterialendothelialcells,Iwilldeterminewhetherhypoxia-inducedmiR-130b decreasesFXNexpression,thusdefiningacausativerelationshipamongmiR-130b,FXN,andFe-Sbiogenesis. 2)DeterminewhetherFXNlossattenuatesmitochondrialrespirationandendothelialfunction.Inprimary endothelialcellsandinduciblepluripotentstemcell-derivedendothelialcells(iPSC-ECs)fromFRDApatients,I willtestthehypothesisthatFXNdeficiencyinducesFe-Scluster-dependentmitochondrialdysfunction,resulting inendothelialphenotypicchanges(e.g.,apoptosis,proliferation).Ifsuccessful,findingscouldestablishakeylink betweenhypoxia-orgenetically-drivenFXNlossandendothelialdysfunctionconsistentwithPH. 3)EstablishwhetherFXNlossandresultingmitochondrialdysfunctionpredisposestoPHinvivo.Ina tamoxifen-dependentendothelialcellFXNknockoutmousemodel,IwilltestthehypothesisthatFXNdeficiency inthepulmonaryendotheliumpromotesmolecular,histologic,andhemodynamicchangesconsistentwithPH.If successful,theseresultswillvalidateanintegralanddirectroleforFXNinthedevelopmentofPH. Significance:Thisprojectisideallystructuredtotrainmeasaphysician-scientistandbridgethegapbetween basicscienceandclinicalmedicine.
I aim tocontributetothecurrentlydeficientunderstandingofFe-Sassembly proteinsinendothelialfunction.IcouldalsoidentifyFXNasakeypathogenicfactorinPH,offeringthepotential ofdiagnosingFRDApatientsatriskforPHanddefiningFXNasanewdrugtargettobenefitallPHpatients.

Public Health Relevance

Pulmonaryhypertensionisadeadlydiseaseofthevesselsthatsupplythelungthatmayinpartbecausedbya deficiencyiniron-sulfurclusters?crucialmetalcomplexesinvolvedinawiderangeofcellularfunctions.Frataxin, aniron-sulfurassemblyprotein,ismutatedinaneurologicdiseasecalledFriedreich?sataxiawherethepresence ofpulmonaryhypertensionhaslargelybeenneglected.Thisproposalaimstoestablishadirectmolecularlink between frataxin and the development of pulmonary hypertension to expand our understanding of diseases dependentuponiron-sulfurclusters,and,ifsuccessful,toimprovemanagementofFriedreich?sataxiapatients andoffernewdrugtargetsformoreeffectivetreatmentofpulmonaryhypertension.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Individual Predoctoral NRSA for M.D./Ph.D. Fellowships (ADAMHA) (F30)
Project #
1F30HL139017-01
Application #
9396442
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Colombini-Hatch, Sandra
Project Start
2017-09-01
Project End
2021-08-31
Budget Start
2017-09-01
Budget End
2018-08-31
Support Year
1
Fiscal Year
2017
Total Cost
Indirect Cost
Name
University of Pittsburgh
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213