MicroRNomics, a newly emerging approach for disease biology
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Review
MicroRNomics:anewlyemergingapproachfordiseasebiology
ChunxiangZhang
RNAandCardiovascularResearchLaboratory,DepartmentofAnesthesiology,NewJerseyMedicalSchool,University
ofMedicineandDentistryofNewJersey,Newark,NewJersey
Submitted7February2008;acceptedinfinalform21February2008
ZhangC.MicroRNomics:anewlyemergingapproachfordiseasebiology.
PhysiolGenomics33:139–147,2008.FirstpublishedFebruary26,2008;
doi:10.1152/physiolgenomics.00034.2008.—Genomicevidencerevealsthat
geneexpressioninhumansispreciselycontrolledincellular,tissue-type,
temporal,andcondition-specificmanners.Completelyunderstandingtheregu-
latorymechanismsofgeneexpressionisthereforeoneofthemostimportant
issuesingenomicmedicine.Surprisingly,recentanalysesofthehumanand
animalgenomeshavedemonstratedthatthemajorityofRNAtranscriptsare
relativelysmall,noncodingRNAs(sncRNAs),ratherthanlarge,proteincoding
messageRNAs(mRNAs).Moreover,thesesncRNAsmayrepresentanovel
importantlayerofregulationforgeneexpression.Themostimportantbreak-
throughinthisnewareaisthediscoveryofmicroRNAs(miRNAs).miRNAs
compriseanovelclassofendogenous,small,noncodingRNAsthatnegatively
regulategeneexpressionviadegradationortranslationalinhibitionoftheir
targetmRNAs.Asagroup,miRNAsmaydirectlyregulateϳ30%ofthegenes
inthehumangenome.InkeepingwiththenomenclatureofRNomics,whichis
tostudysncRNAsonthegenomicscale,“microRNomics”iscoinedhereto
describeanovelsubdisciplineofgenomicsthatstudiestheidentification,expres-
sion,biogenesis,structure,regulationofexpression,targets,andbiologicalfunc-
tionsofmiRNAsonthegenomicscale.Agrowingbodyofexcitingevidence
suggeststhatmiRNAsareimportantregulatorsofcelldifferentiation,proliferation/
growth,mobility,andapoptosis.ThesemiRNAsthereforeplayimportantrolesin
developmentandphysiology.Consequently,dysregulationofmiRNAfunctionmay
leadtohumandiseasessuchascancer,cardiovasculardisease,liverdisease,
immunedysfunction,andmetabolicdisorders.microRNomicsmaybeanewly
emergingapproachforhumandiseasebiology.
microRNAs;genomics;geneexpression;cancer;cardiovasculardisease
ITISCLEARTHATGENEEXPRESSIONinthehumanisprecisely
controlledinacell,tissue,time,andcondition-specificmanner.
Large-scalemicroarraydatasuggestthatdifferentcells,tissues,
andorgansystemswithinanorganism(includinghumans)
havedifferentgeneexpressionprofiles,althoughtheyhavethe
samegenome.Moreover,thesegeneexpressionsignaturesare
sensitivetochangesincondition,suchasdevelopment,dis-
eases,environmentchanges,andtherapeuticdrugs(10,36,75,
94).Therefore,completelyunderstandingtheregulatorymech-
anismsofgeneexpressionisoneofthemostimportantissues
ingenomicmedicine(36,59,75,97).Anyimportantbreak-
throughsinthisresearchareawillhavethepotentialtogive
risetoimpactsonmodernclinicalmedicineindiagnosisand
therapy,becausemostofhumandiseasesaremultigene(mul-
tifactor)diseases,inwhichtheexpressionofmultiplegenesis
changeddirectlyorindirectly(15,19,41,91).
SincethediscoveryoftheDNAdouble-helixstructureby
WatsonandCrick(120)in1953,thestandardpathwayofinformationflowinacellfromDNAtomessageRNA
(mRNA)toproteinhasbeenthedominantthemeinmolecular
biology.However,recentanalysesofthehumanandanimal
genomeshavedemonstratedthatthemajorityofRNAtran-
scriptsarenotproteincodingRNAs(mRNAs),butnoncoding
RNAs(ncRNAs)(77,105,108).Indeed,large-scalecomple-
mentaryDNAsequencingandgenometilingarraystudieshave
shownthatϳ50%ofgenomicDNAinhumansistranscribed
intoRNAtranscripts,ofwhich2%istranslatedintoproteins
andtheremaining98%isncRNAs(38,77,78,105,108).In
general,thesizesofthemajorityofncRNAspeciesvaryfrom
18ntto500nt,wellbelowthesizeofthemajorityofmRNA
species,andarethereforetermedsmallncRNAs(sncRNAs).
ThetermncRNAiscommonlyemployedforRNAthatdoes
notencodeaprotein,butthisdoesnotmeanthatsuchRNAsdo
notcontaininformationorhavefunction(38,77,78,105,108).
Forexample,ribosomalRNAsandtransferRNAs,whichmake
upalargeproportionofRNAbasedonamount,aretwoknown
sncRNAsthatprovidehelpforproteinexpression.Quitere-
cently,twonovelclassesofsncRNAswerediscovered:
microRNAs(miRNAs)andsmallinterferingRNAs(siRNAs)
(38,78,108).BothhavestrongregulatoryeffectsonmRNA
translationandrepresentanovelimportantlayerforgene
expression(38,78,108).AnalogoustothefirstRNA
revolu-Articlepublishedonlinebeforeprint.Seewebsitefordateofpublication
(http://physiolgenomics.physiology.org).
Addressforreprintrequestsandothercorrespondence:C.Zhang,RNAand
CardiovascularResearchLaboratory,Dept.ofAnesthesiology,NewJerseyMed-
icalSchool,Univ.ofMedicineandDentistryofNewJersey,185So.OrangeAve.,
MSB-E548,Newark,NJ07101-1709(e-mail:zhangc3@umdnj.edu).PhysiolGenomics33:139–147,2008.
FirstpublishedFebruary26,2008;doi:10.1152/physiolgenomics.00034.2008.
1094-8341/08$8.00Copyright©2008theAmericanPhysiologicalSociety139