Abstract

) Mutationisthesourceofgeneticvariationandcangiverisetodisease,aging,andcancer.Mammalshaveso- phisticatedpathwaystoreducemutationbyrepairingerrorsoccurringduringDNAreplicationaswellasdam- ageduetoenvironmentaleffects.Whilemanybiologicalpathwayshavebeenextensivelystudied,otherun- knownDNArepairpathwaysmayremainundiscovered.Wehypothesizethatonesuchpathwayisthecircadi- anclockpathway.Thescientificpremiseofourproposalisthatstudieshaveshownmiceharboringgenetic disruptionofcircadianclockfunctionexhibitincreasedtumorformationandacceleratedaging.Further,epide- miologicalstudiessuggestcircadiandisruptionisalikelycarcinogen.Whilemammaliancorecircadianclock proteinsCRY1andCRY2seemtolackcatalyticDNArepairactivity,theyevolvedfrombacteriallight-activated DNArepairenzymes(CPDphotolyases).Lastly,wehaverecentlyshownthatCRY2-deficientcellscontain significantlyelevatednumbersofdoublestrandbreaks,andCry2-/-miceareuniquelybornatsub-Mendelian ratios,suggestinganincreaseinlethalmutations. Basedontheseobservationsandthispremise,wehypothesizethatmammalianCRY2hasmaintainedafunc- tionalconnectiontoprotectinggenomeintegrity,andthatdisruptionofthisfunctionincreasesgenome-wide mutationrates,whichinturncontributestoelevatedcancerriskcausedbyenvironmentalcircadiandisruption. Totestthishypothesis,wewillmeasuremutationratesinwildtypeandCry2-/-littermatemicesubjectedto standardhousingconditionsortoenvironmentalcircadiandisruptionbyperformingwhole-genomesequencing.
In Aim1 ofthisproject,wewilltestwhetherCry2-/-micehaveelevatedgermlinemutationratescomparedwild- type.Todothis,wewillperformthreeindependentcrossesfromwhichwewillsequencebothparentsand threeoftheirprogenyandcountthenumberofdenovomutationspresentintheprogeny.Wewillcomparethe numberofaccumulatedmutationsinprogenyborntoCry-deficientparentstothatinoffspringborntowild-type parents.Becausemutationsmaynotoccurequallyinmaleandfemaleparents,wewillexamineoffspringfrom maleorfemaleCry2-deficientparentsbredtowildtypepartners.
In Aim2 ofthisproject,wewilltestwhether environmentalcircadiandisruptionincreasesgermlinemutationrates.Todothis,wewillbreedamouseex- posedtochronicjetlaglightcyclestoawild-typeparentandsequencethegenomesoftheparentsand3of theprogeny.Wewillcomparethenumberofdenovomutationstothatnumberinoffspringborntoparentsex- posedtonormallight-darkcycles.Successfulcompletionofthisresearchwillindicatewhetherenvironmental disruptionofcircadianclockscanaffectgenomeintegrity,layingthegroundworkforfurtherstudiesofthe mechanismofcircadiandisruptionondisease.

Public Health Relevance

Environmentaldisruptionofcircadianrhythmshasbeenlinkedtoincreasedrisksofmetabolic diseaseandcancer,andreducedfertility.CRY2isacriticalcomponentofthemammalian circadianrhythmmachinerythatisrelatedtoDNArepairenzymes,butitsroleinDNArepairis unknown.ThisprojectusesfunctionalgenomicstomeasuretheimpactongermlineDNA mutationratesincurredbydisruptingcircadianrhythms,eitherbyenvironmentalalterationsof thelightcycleorbygeneticdeletionofCRY2.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21ES031000-01
Application #
9840238
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Reinlib, Leslie J
Project Start
2019-08-15
Project End
2021-07-31
Budget Start
2019-08-15
Budget End
2020-07-31
Support Year
1
Fiscal Year
2019
Total Cost
Indirect Cost

  Institution

Name
Scripps Research Institute
Department
Type
DUNS #
781613492
City
La Jolla
State
CA
Country
United States
Zip Code
92037