Pioneer Transcription Factors in Pituitary Development And

1 184

H Juliette and others Pioneer transcription factors in 184:1 R1–R15 Review pituitary

MECHANISMS IN ENDOCRINOLOGY Pioneer transcription factors in pituitary development and tumorigenesis Correspondence should be addressed Juliette Harris, Arthur Gouhier and Jacques Drouin to J Drouin Institut de Recherches Cliniques de Montréal, Laboratory of Molecular Genetics, Montréal, Quebec, Canada Email [email protected]

Abstract

Pioneer transcription factors have key roles in development as master regulators of cell fate specification. Only a small fraction of all transcription factors have the pioneer ability that confers access to target genomic DNA sites embedded in so-called ‘closed’ heterochromatin. This ability to seek and bind target sites within the silenced portion of the epigenome is the basis for their role in changing cell fate. Upon binding heterochromatin sites, pioneer factors trigger remodeling of chromatin from a repressed into an active organization. This action is typically exerted at enhancer regulatory sequences, thus allowing activation of new gene subsets. During pituitary development, the only pioneer with a well-documented role is Pax7 that specifies the intermediate lobe melanotrope cell fate. In this review, a particular focus is placed on this Pax7 function but its properties are also considered within the general context of pioneer factor action. Given their potent activity to reprogram gene expression, it is not surprising that many pioneers are associated with tumor development. Overexpression or chromosomal translocations leading to the production of chimeric pioneers have been implicated in different cancers. We review here the current knowledge on the mechanism of pioneer factor action.

European Journal of Endocrinology (2021) 184, R1–R15 European Journal of Endocrinology

The essence of pioneer action

Pioneer factors are transcription factors that have, in of this chromatin (1, 2). This unique property allows addition to the usual properties of other transcription pioneer factors to implement new programs of gene factors (TF), the unique ability to recognize their target expression through opening of the chromatin landscape DNA sequence within condensed, so-called ‘closed’, at regulatory elements, such as enhancers and promoters. chromatin or heterochromatin, and to trigger opening Consequently, this property enables pioneer factors to act

Invited Author’s profile Jacques Drouin is Director of the Laboratory of Molecular Genetics at the Institut de recherches cliniques de Montréal, Canada. He is Professor of Biochemistry at Université de Montréal and a member of its Molecular Biology Program. He is a member of the Departments of Biochemistry, Anatomy and Cell Biology, and of the Division of Experimental Medicine at McGill University, Canada. His research interests center on the molecular basis of pituitary gland function, development and diseases, and encompass discovery of transcriptional regulators (Pitx1, Tpit and Pax7) that control cell differentiation, organogenesis and are implicated in diseases. He also studies transcriptional mechanisms of hormone action and hormone resistance in Cushing’s disease.

https://eje.bioscientifica.com © 2021 European Society of Endocrinology Published by Bioscientifica Ltd. https://doi.org/10.1530/EJE-20-0866 Printed in Great Britain Downloaded from Bioscientifica.com at 10/03/2021 11:46:00PM via free access

-20-0866 European Journal of Endocrinology https://eje.bioscientifica.com typically inactiveandwithitsDNAheavilymethylated the highlycompactedportionof(epi)genomethatis DNA sequences in heterochromatin (heterochromatin is property ofbothtypesistheirabilitytorecognizetarget target enhancers forchromatin opening. A common the pioneers involved in cell differentiation that primarily trigger large-scale chromatin rearrangements and second, the so-calledpluripotencyfactors(egSox2,Oct4)that Already, twotypesofpioneerscanbedistinguished;first, that suggest there may well be different types of pioneers. to havepioneeractivitywithaspectrumofproperties thousands ofTFs,abouttwohandfulsarecurrentlyknown hence, theyarekeyregulatorsindevelopment.Ofthe as masterregulatorsofcelldifferentiationandfate; Review H Julietteandothers various pioneerfactorswithaparticularemphasisonone unknown. Thisreviewfirstdiscussesthepropertiesof pioneers, theunderlyingmechanismsremainlargely an activechromatin,isdescribedtosomeextentformany switch fromarepressed chromatin organization toward changes associatedwithchromatinopening,namelythe culture models.Whereasthenatureofchromatin pluripotent cells(iPS),thisoccursoverweeksintissue In complexcasessuchasthereprogrammingofinduced chromatin openingbypioneersisrelativelyslow( DNA targetswithinheterochromatin,thetimecourseof for eachtypeofpioneeristhesame.Afterrecognition whether the nature ofthe permissive heterochromatin at CpGdinucleotides),butitisyettobedetermined pituitary Pioneer transcriptionfactorsin action. Themechanismofpioneer Mechanism ofpioneertranscriptionfactor Figure 1 repressed genesinagivencell type. genome thatcontainsinactive or or closedchromatinportionof the(epi) Heterochromatin isthehighly compacted demethylation ofenhancerDNA. epigenetic memoryisestablishedthrough inducible systeminAtT-20cells.Finally, left thatweredeterminedusingan follows. Thetimecourseprovidedonthe such asTpit.Targetgeneexpression other nonpioneertranscriptionfactors this isassociatedwithrecruitmentof dependent melanotropesetofenhancers, enhancer markH3K27ac.ForthePax7- accessibility anddepositionoftheactive completed byappearanceofDNA H3K4me1. Chromatinopeningis deposition oftheactiveenhancermark stabilization ofPax7bindingand H3K9me2 ( methylation andthehistonemark that istypicallymarkedbyDNA within heterochromatin(definedbelow) recognition oftargetDNAsequences aspect ofpioneeractionresidesin a melanotrope-likefate( leads tocellfatetrans-differentiationinto corticotrope modelcellline,Pax7action action inpituitaryAtT-20cells.Inthis using dataderivedfromanalysesofPax7 transcription factoractionisillustrated Downloaded fromBioscientifica.com at10/03/202111:46:00PM 6 ). Thisisfollowedby 184 :1 4 ). Theunique Fig. 1 R2 via freeaccess ). European Journal of Endocrinology heterochromatin forappropriate pioneersites.Sequence represent a scanning mechanism to scout throughout proposed thatinteractions at thesedegeneratesitesmay attranscriptionaltargets( observed conservation thanthelevelof binding motifsthatareless conserved FoxA, thissubsetofbindingsitesisassociatedwithDNA appear toberesistantthepioneeringaction( with anychromatinchange( in ChIPseq, sites (farmorethanregularnonpioneerTFsasobserved many pioneershavelargesubsetsofgenomicbinding that section. Thisabilitymayaccountfortheobservation heterochromatin proteinsasdiscussedinthenext may therefore be their ability to interact with critical them torecognizetheirtargetsinheterochromatin factor inordertoallowpioneeraction. interactions inthemselvesarenotdifferentoracritical found atpioneeredenhancerssuggestthatpioneer:DNA complex. Altogether, DNAsequencemotifs theconserved requirements forpioneeringthereforeappearmore present at all pioneered enhancers and the DNA sequence pioneering process;however, thesecompositesitesarenot suggests thathigheraffinityDNAsitesmayfavorthe is enriched compared to other enhancers ( the frequencyofitsoccurrenceatpioneeredenhancers composite motifappearstobeahigheraffinitysiteand a pairedmotifjuxtaposedto a homeodomain motif: this cellsrevealedacompositemotifthatcontains pituitary The characterizationofenhancerspioneeredbyPax7in most targetenhancerscontainingeithermotiforboth. Pax7 DBDcanrecognizeacognateDNAsequencewith (DBD), onepaireddomainandhomeodomain.Each pioneer Pax7.ThishastwoDNAbindingdomains for allpioneersstudiedsofarbutaninterestingcaseisthe their transcriptional targets ( comparedto significant differencesofmotifconservation by pioneers at their pioneered targets did not show Indeed, theanalysisofDNAsequencemotifsrecognized following pioneer-dependentchromatinremodeling. refer to‘pioneered’sitesasthosethatareopened within openchromatin.Throughoutthisreview, we that aresimilartothebindingofsameTFssites is dependentonDNAsequencerecognitionconstraints factors intumorigenesisisreviewed. pioneer actionsandfinally, theimplicationsofpioneer development isdiscussedinthecontextoftheirputative Pax7. TheimplicationofvariousTFsinearlypituitary development, pioneer extensivelystudiedinpituitary Review The discriminatingfeatureofpioneersallowing Recognition ofpioneeredgenomicDNAtargetsites Fig. 2A ) where binding is not associated 3 , 3 4 , ). This appears to be true H Julietteandothers 6 , 7 ). Thesesitesthus 4 , 3 5 ). Itwas ). This 6 ). For with facultativeandconstitutiveheterochromatin, H3K9me2 andH3K9me3marksarehistoricallyassociated or tri-methylationoflysine9histoneH3( or closedheterochromatinistypicallymarkedbydi- by marksassociatedwithactiveenhancers.Repressed replacement of repressive PMT marking heterochromatin Chromatin openingbypioneerfactorsinvolvesthe (PMT) that define euchromatin and heterochromatin. thepost-translationalmodifications and theycarry Nucleosomes are the basic units of chromatin condensation and chromatin Pioneer interactionswithnucleosomes heterochromatin interactionsfordifferentpioneers. related tointrinsicdifferencesinthemechanismsof at similar subsets of sites. These differences may be forPax7 motif degenerationwashowevernotobserved deposition oftheH3K27acmarkatactiveenhancers( that hashistoneacetylaseactivityresponsibleforthe marked bythepresenceofgeneralcoactivatorp300 Fig. 2B ATACseq (assay fortransposase-accessiblechromatin, FAIREseq andmostlyusedtoday, thetechniqueof accessibility. ThesetechniquesincludeDNasesensitivity, is typicallyrevealedbytechniquesthatmeasureDNA further associatedwithdepletionofnucleosomesthat lineage specification( condensation and arecrucial for properdevelopmental domains areassociatedwithhigher-orderchromatin maintenance ofH3K9me3areknocked-down( Oct4 andSox2recruitment,exceptifproteinsinvolvedin constitute abarriertopioneerbindingastheyimpair H3K9me3-enriched heterochromatindomainsseemto at enhancersandH3K4me3promoters( and instead,markedwiththeactivatingPTMsH3K4me1 active chromatinisdepletedoftheserepressivemarks packed intoregulararraysofnucleosomes.Incontrast, respectively, andbothtypesofheterochromatin are dependent chromatinremodelers suchastheSWI/SNF recruit and/orbedependent ontherecruitmentofATP- ( marks were characterized and are reviewed elsewhere complexes responsibleforimplementing manyofthese subsets ofgenes.Enzymesandremodelingprotein leading toenhanceractivationandexpressionofnovel chromatin organizationfromrepressivetoactivestate, Thus, pioneerfactorsinitiatetheprocessofswitching pituitary Pioneer transcriptionfactorsin 13 , At active regulatory elements, activating marks are At active regulatory 14 ) ( ). Also,multiplepioneerfactors wereshownto 12 ). Transcriptionally active enhancers arealso 11 ). Downloaded fromBioscientifica.com at10/03/202111:46:00PM https://eje.bioscientifica.com 184 :1 9 ). Notably, 10 8 ). These ). These R3 9 via freeaccess ). European Journal of Endocrinology https://eje.bioscientifica.com Pioneer actionisassociated withthesetwosubsetsof center asrevealedbyDNAaccessibility (egbyATACseq). enhancers alsoexhibitnucleosome depletionintheir are usuallyalsomarkedby p300andH3K27ac.Active whereas enhancersactivelyinvolvedintranscription may beconsideredasprimedandismarkedbyH3K4me1 actively involvedintranscription( potential to be active compared to enhancers that are identified differencesbetweenenhancersthathavethe chromatin states( in contrasttothecleardescriptionofbeforeandafter pioneer factoractionremainshoweverlargelyundefined temporal sequence of chromatinchanges occurring during complex forchromatinopening( Pax7 whereasthestrongerpeakrevealspositionofapalindromicDNAbindingTpitsite( exhibit pioneeractivityandrequiresprioractionofPax7foritsrecruitmenttotheenhancer.ThelesserTpitpeakco-migrates with H3K4me1, recruitmentofthegeneralcoactivatorp300andfinallytranscriptionfactorTpit.Tpitdoesnot itself the enhancersequence:thisisassociatedwithappearanceofanATACseqpeak,depositionactivemark enhancer ofthe sequenced tomapgenomicregionsthatexhibitDNAaccessibility.(C)ChIPseqandATACseqprofilesareshownforthelandmark double-stranded DNAwhenchromatinstructureallowsaccess.Fragmentsliberatedthroughthetransposase’saction are (Assay forTransposase-AccessibleChromatinusingsequencing)reliesontheabilityoftransposaseTn5tocleaveand tag epitopes maybetranscriptionfactorsorhistonemarksthatdefinedifferentchromatinstates.(B)ThetechniqueofATACseq throughput DNAsequencing.(A)TheChIPseqtechniqueusesanantibodytoassessthepresenceofepitopesonchromatin; these The pioneeraction.assessmentofactionisachievedusingprimarilytwogenome-widetechniquesfollowedby high Figure 2 Review Numerous studiesofenhancerchromatinlandscapes PCSK2 Fig. 2C genethatisopenedandactivatedfollowingPax7pioneering.TheChIPseqforshowsitsbindingto ). H Julietteandothers 15 9 ). Theformergroup , 16 , 17 ). Theexact condensation ( promotes chromatincondensation andspreadofthe By homodimerizing, it bridges nearby nucleosomes and mark andistherebyrecruited toheterochromatinregions. HP1 proteins suchasHP1 decorated byagroupofspecificchromatin-associated of therepressivehistonemarksdescribedabove,itisalso by linkerhistonesH1( wrapped aroundnucleosomesandfurthercompacted states definesequentialstepsinenhanceractivation. ( enhancer subsetwhereasanotherisfullyactivated enhancers: forPax7,pioneeringresultsinprimingofan pituitary Pioneer transcriptionfactorsin 6 ). This observation suggeststhatthese twoenhancer ). Thisobservation Condensed heterochromatinischaracterizedbyDNA α forinstancerecognizestherepressiveH3K9me2/3 19 ). HP1 α / β 4 / γ ). 18 Downloaded fromBioscientifica.com at10/03/202111:46:00PM ( α 19 alsohastheabilitytolead ). Inadditiontothepresence ) orKAP1(Tif1 184 :1 β /Trim28, ( 20 R4 via freeaccess )). European Journal of Endocrinology overall increaseinDNAaccessibility isdelayedandmore that even if it binds its target sites quickly, the subsequent to inducechromatinremodeling ability toopencompactednucleosomearrays involved in nucleosome interactions that impairs its interaction issupportedbyamutationinFoxAdomain their interactionwithchromatin.Theimportanceofthis may facilitate nucleosomal DNAbinding by increasing formanypioneerfactors( was observed pioneer factors. Finally, nonspecific nucleosome binding MNase-seq ( binding siteswithnucleosomesusingthetechnique of thecolocalization oftheir Oct4 andSox2byobserving binding washighlighted by transientunwrapping at its edges ( taking advantageofnucleosomedynamicscharacterized extremities ofnucleosomalDNA( can only recognize their target motif effectively at the ( its structureinawaythatincreasesDNAaccessibility either thenucleosomedyadorextremitiesandimpacting binding motif on the nucleosome, efficiently binding at their heterodimers are sensitive to the position of their exposed onthenucleosomesurface( binding motif,therebyfacilitatingtheofbases Klf4 canrecognizepartialsequencesfromtheirconsensus increased DNAaccessibility( near thenucleosomedyad,resultinginH1ejectionand histone H1andmaypreferentiallytargetmotifslocated helix DNA-bindingdomainresemblingaoflinker nucleosome binding patterns. FoxA possesses a winged- binding mechanismswereproposedtoaccountfordiverse Sox2, Klf4,Zelda,PU.1orAscl1( to bindnucleosomalDNA ( site inreconstitutedandcompactednucleosomearrays experiments of FoxA2 and GATA4 binding to their target byDNaseIfootprinting barrier camefromtheobservation barrier toTFrecruitment( this chromatinorganisationisclassicallyviewedasa others, inthedepositionofH3K9me2/3( repressive histonemethyltransferasesinvolved,among and maintenanceasitmediatestherecruitmentof factors ( condensation andtherecruitmentofotherrepressive the chromatininanenvironmentthatwouldfavorits to heterochromatinphaseseparation,thuscapturing 23 30 Review , , The firstevidenceofpioneerfactorsovercoming this The studyofPax7pioneering kinetics( 31 24 , ). To date,severalTFsandpioneerswereshown 21 32 ). KAP1iscrucialforheterochromatinformation ). Otherpioneerfactors,suchasp53orPU.1, 3 ), butsuchcolocalizationisnotseenforall 22 in vivo invitro ). 23 , H Julietteandothers forsomepioneerslike 28 in vivo 3 , includingp53,Oct4, , , 25 33 29 35 , 3 , 3 ( ). Oct4,Sox2and , 26 ). Sox2,Oct4or , 36 38 34 20 33 , Fig. 1 ). Nucleosome ). ), potentially 27 ). Altogether, , 37 in vitro ). Different ) revealed ) andthis and DNA methylation patterns is critical for the stability of cytosines withintheCpGdinucleotide. Maintenanceof with repressedchromatinstates, namelymethylationof genomic DNA also bears a modification that is associated histone tails and their associated chromatin components, were before replication. In addition to epigenetic marks on closed chromatinarereassembledafterreplicationasthey passage ofthereplicationapparatussuchthatopen or ( chromatin statesthroughcelldivisions(reviewed in this inheritanceisenactedbymechanismsthatmaintain through pioneerfactoraction).Attheepigenomelevel, divide unlessadifferentiationprocessisactivated(e.g. Cell identity must be stable and maintained as cells shot deal! Pioneering andepigeneticmemory:aone- vivo change; atanothersubset,itonlyleadstoenhancer recruitment doesnotresultinanyapparentepigenetic revealed alargesubsetofso-calledResistantsiteswhere cells the caseofPax7,itsbindingprofileinpituitary on thechromatin-associatedproteinPARP1 ( recruitment atasubsetofitsbindingsitesisdependent to asubsetofitspotentialbindingsites( instance, GATA4 significantly increases FoxAbinding the requirement ofspecificcofactorsatsomeloci.For due totheexpressionofcell-type-specificpartnersor lineage-specific bindingpatterns( of theirpotentialbindingsitesgenomewideandexhibit pioneer factorsareonlyefficientlyrecruitedtoafraction these twoprocessesmaybemechanisticallydistinct. automatically reflected bychromatin openingand that of pioneerfactorstotargetcondensedchromatinisnot will never be opened highlights that the unique ability progressive ( pioneer factorstoovercome chromatincondensation may beparamounttounderstandtheuniqueabilityof elements.Bettercharacterizingthem genes orregulatory the absence of epigenetic marks associated with active remain poorlydescribedandarestillmainlydefinedby stabilization or action. These chromatin environments more orlesspermissivetopioneerfactorrecruitment, existence ofvariouschromatinenvironmentsthatare chromatin opening( priming andnottothefullactivationcharacterizedby pituitary Pioneer transcriptionfactorsin 40 )). Indeed,chromatinorganizationismaintainedafter aswelltheirmechanismsofaction. Despite theirabilitytotargetcondensedchromatin, 6 ). Thisandthefactthatmanyboundtargets 6 ). Collectively, thissuggeststhe Downloaded fromBioscientifica.com at10/03/202111:46:00PM https://eje.bioscientifica.com 7 , 184 10 :1 ). Thiscouldbe 7 ) andSox2 39 ). In R5 via freeaccess in in European Journal of Endocrinology https://eje.bioscientifica.com methyltransferases (e.g.ubiquitination ofH3lysinesby DNA methylation.Some histone PTMsrecruitDNA There iscrosstalkbetween histonemodificationsand organization togetherwith histonemodifications. Interestingly, DNAmethylation alsoinfluenceschromatin accessibility andpreventrepressivemarksspreading. activating PMTmightnotbeenoughtomaintain by condensedchromatin,nucleosomemarkingwith term maintenance.Sincepioneeredsitesaresurrounded with theintroductionofactivatingmarksforlong- removal ofrepressivePMTs maybeneededtogether activating marks.Inthecontextofpioneeraction, randomly redistributedafterandthenre-markedwith marks appeartodissociatefromDNAatreplication,be structure ( and thusensuringmaintenanceofacondensedchromatin allowing themtospreadonnaiveadjacentnucleosomes synthesized DNA, keeping these PMTs and presumably heterochromatin aretransferredwholetonewly epigenetic marks(e.g.H3K9me3)onconstitutive study, parentalnucleosomesmarkedwithrepressive daughter cellsaftercelldivision.Accordingtoarecent of theiruniqueproperties. retention ofpioneerfactorsonreplicatingDNAisanother linked to nucleosome occupancy. We speculate that the retain thesefactors,theirmaintenanceseemingtobe Interestingly, notallthesitesboundbyFoxA1andGATA1 GATA1 ( as ‘bookmarkingproteins’.TheseincludeFoxA1( DNA replication, at least partially, and they are labeled nonetheless abletomaintaintheirpositionduring to dissociate from DNA. However, some proteins are Indeed, thereplicationapparatusforces mostproteins chromatin structureandprotein–DNAinteractions? during replicationforkpassage,aprocessthatdisrupts pioneering processbeingdependentonreplication. chromatin openingisconsistentwithsomestepsofthe fate changes,theslowtimecourseofpioneer-driven showing a need for DNA replication to implement cell methylation. Taken togetherwith ample priordata proteins andtheirmarks,togetherwithchangesinDNA state: thatinvolvesamajorreorganizationofchromatin opening ofclosedchromatinfromaninactivetoactive a newcellfate.Thisisachievedthroughpioneer-driven expression of a new repertoire of genes, thus implementing this genomicDNAmark. dependenton isvery cell identityandepigeneticmemory Review Globally, chromatin organization is maintained in How couldpioneerfactorsmarktheirgenomictargets The purposeofpioneerfactorsistoactivatethe 42 44 ) and Sox2 ( ). Incontrast,nucleosomesbearingactive 43 ), all three being pioneer factors. H Julietteandothers 41 ),

gene promoters and 5’/3’ cis-regulatory regions( gene promotersand5’/3’cis-regulatory genome isnotrandom.Indeed,mostCpGsarefoundat than statisticallyexpected( patterns. Inmammals,CpGdinucleotidesarelessfrequent Dnmt1 that maintains established DNA methylation (Dnmts), either DNA methylationisperformedbymethyltransferases implantation. ones beingestablishedaroundembryonic determined patternsinmammaliandevelopment,thefirst chromatin. Genomic DNA methylation follows pre- repression ( High levelsofmethylationcorrelatewithtranscriptional is oneofthemostextensivelystudiedepigeneticmarks. HDAC1/2, histonedeacetylases( by MeCP2whichrecruitsSin3,acomplexcontaining induce somePTMs(e.g.methylatedDNAisbound methylase ( Uhrf1 favorstherecruitmentofDnmt1,maintenance stability ( vital forcorrectdevelopment,beingessentialgenomic ( In somaticcells,70–80%ofCpGsitesaremethylated 70% ofannotatedpromotersarewithinCpGislands( that areassociatedwithpromoters(inhuman,around often form highly enriched clusters, called CpG islands, the likelybasisoflong-term epigenetic memory. of Pax7( marks aftermorethantwelve cellpassagesintheabsence by Pax7retainaccessibility and activeepigenetichistone to itspioneeredtargetsanymore. Infact,sitespioneered their geneexpressionprofilewhenthepioneerisnotbound oftheiraction,allowing cellstopreserve long-term memory It washowevershownthatpioneerslikePax7implement a putative roleof DNA demethylationin the pioneeraction. is sufficientforittohappenunknown,aswellthe the pioneeractionorsolepresenceofafactor anymore ( opens chromatinbutdoesnottriggerDNAdemethylation DNA replication:whenthecellcycleisblocked,FoxA2still of FoxA2,thetwoprocesseswereseparatedbyblocking action, orwhetheritiscauseconsequence.Inthecase (de)methylation isaparallelmechanismofthepioneer methylation maintenance.ItisunclearwhetherDNA ( eleven-translocation (Tet) enzymes(DNAdemethylases) involving eitheractiveDNAdemethylationexertedbyTen- ( and transcriptionalregulation( pituitary Pioneer transcriptionfactorsin 51 56 7 , ) or a passive mechanism involving blockade of DNA ) orapassivemechanisminvolvingblockadeofDNA ). Themethylationpatternsandtheirmaintenanceare DNA methylation at cytosines of the CpG dinucleotides DNA methylationatcytosinesoftheCpGdinucleotides Several pioneer factors can trigger DNA demethylation Several pioneerfactorscantriggerDNAdemethylation 56 ). Different mechanisms may be responsible, ). Differentmechanismsmayberesponsible, 6 52 ). DNA demethylation of pioneered enhancers is ). DNAdemethylationofpioneered enhancersis 7 47 , ). Whether DNA demethylation is a step of ). WhetherDNAdemethylationisastepof 45 53 ) and they are highly linked with condensed ) andtheyarehighlylinkedwithcondensed )), andDNAmethylationcanindirectly ), cell differentiation ( de novo Downloaded fromBioscientifica.com at10/03/202111:46:00PM Dnmts (Dnmt3a, Dnmt3b) or Dnmts(Dnmt3a,Dnmt3b)or 48 ) and their distribution in the ) andtheirdistributioninthe 47 46 ). )). 184 54 ), imprinting ( :1 49 ). They ). They R6 50 55 via freeaccess ). ). ) European Journal of Endocrinology it isinvolvedinmaintenanceof theprogenitorstate. action ofthesefactorsisrequired forpituitarycelldifferentiation.TheTFSox2isapluripotency factor,ithaspioneeractivityand NeuroD1, MASH1(Ascl1)andGATA2 wereshowntohavepioneeractivityinothersystems,but itisnotyetclearwhetherpioneer ( investigators supportedtheroles ofvarioustranscriptionfactorsduringpituitarycelldifferentiation; thisisreviewedelsewhere Transcription factorcontrolofcelldifferentiationduringpituitary development.Alargebodyofworkfromnumerous Figure 3 critical fortheprogressionofRathke’s pouchintothe Pitx2 The stomodealectodermexpressestherelated forms at the midline in the back of the stomodeal cavity. primordium,Rathke’soral ectoderm.Thepituitary pouch, ectoderm thatformsthestomodeumandbecomes review ofestablisheddata. a relativelyspeculativediscussionratherthantraditional intermediate lobe melanotropecells, this sectionpresents development throughpioneeraction,Pax7specifyingthe only oneTFisclearlyshowntoexertitsroleinpituitary per seasthishasbeenextensivelyreviewed( development will notreviewthetopicofearlypituitary development.Thesection TFs thatarecriticalforpituitary this sectionwilldiscusstheputativepioneerfunctionof developmentandcelldifferentiation( pituitary field. Throughabriefreviewofcurrentknowledgeonearly development that has advanced the controlling pituitary andinvestigationofTFs it ismostlythediscovery formation, onpituitary first halfofthetwentiethcentury Beyond the developmental studies performed during the Early pituitarydevelopmentandpioneers 57 Review ). Pax7pioneeractivityisrequired duringpituitarydevelopmentformelanotropecellspecification. Inaddition,theTFs The pituitary developsfromtheanteriorneural The pituitary (Pituitary homeobox1/2) genes and these TF’s (Pituitary are H Julietteandothers 57 Pitx1 ). Since Fig. 3 and ), double development(attheearlypouchstage)as pituitary hence thedouble developmental rolesascribedto suggests thatthelatermayfulfillmanyofearly downstream ( does not have heterochromatin interaction properties and indeed,thelimited data available suggest that Pitx1 as yetnoevidencethatthesefactorshavepioneeractivity expression ( of thisfamilyPitx1throughitsroleincontrolPOMC property that led us to discover the founding member expression of hormone coding genes. Indeed, it is this specific role notablyinthemaintenanceofpituitary cells, these TFs are essential, playing a critical pituitary expression inthestomodeumtofullyfunctioningadult ( adult glandularpituitary but itsexactroleisnotwelldefinedanditknown stem state,theytransientlyexpresstherelatedSox9, pioneer factorSox2.Whentheseprogenitorsexittheir cleft in the adult gland express the pluripotency pituitary stemcellsthatlinethe well asthepoolofadultpituitary pituitary Pioneer transcriptionfactorsin 6 ). The Cells of the pituitary primordium,Rathke’sCells ofthepituitary pouch,as Lhx3/4 Pitx1/2 59 Lhx3/4 mutant( ). Despitetheircriticalimportance,thereis genesarerequiredforexpressionofthe Pitx1/2 TF-codinggenes and geneticevidence 58 Downloaded fromBioscientifica.com at10/03/202111:46:00PM mutanthassimilarlyarrested ). 58 ). From the onsetof their https://eje.bioscientifica.com Pitx1/2 184 :1 inthepituitary, R7 via freeaccess European Journal of Endocrinology https://eje.bioscientifica.com between neuralandsurface ectodermthatismaintained is auniquetissue:indeed, it istheonlycontactpoint In thedevelopmental context, theintermediate pituitary melanotrope fatePax7 Specification ofintermediatelobe below. intermediate lobemelanotropefateandthisisdiscussed its actionthroughpioneerisPax7thatspecifiesthe nature ofthisroleremainspoorlydefined. developmentthroughpioneeraction, butthe in pituitary intermediate lobe( lobe whereasMASH1isexclusivelyexpressedinthe primarily expressedincorticotropesoftheanterior withNeuroD1 expressed inthedevelopingpituitary 71 pioneer activityduringneuronaldevelopment( pioneer action. these twolineagesandthiscouldwellbeexertedthrough ( pituitary (both GATA2 andGATA3 areexpressed inthedeveloping share acommonprecursor, itcouldbethatGATA factors ( marker hormonegenesareexpressedlaterindevelopment the putativepioneerfactorGATA2 atthattimebuttheir lobe, namelygonadotropesandthyrotropesthatexpress at a similar time asthe corticotrope lineage in the anterior discussed below( the relatedmelanotropecellstoestablishthiscellfateas noteworthy thatTpitcooperateswiththepioneerPax7in does notappeartohavepioneeractivity( earlier andhenceitmaynotbesurprisingthatTpititself 65 terminates theprocessofcorticotropedifferentiation( differentiation bytheTboxfactorTpit( in the anterior lobe are the corticotropes driven toward known. Theearliestcellstoreachterminaldifferentiation in EMT but whether this involves pioneer action is not Pit) ( transition (EMT)thatrequirestheTFPROP1(Prophet-of- and this occurs through an epithelium-mesenchyme the ventralpartofearlyglandularepithelialpituitary ( ( progenitors TF and itsroleinmaintenance of pituitary whether ithaspioneeractivity( 67 61 Fig. 3 Review ). ThesebHLHTF’s, NeuroD1andMash1(Ascl1),are ), cellsdestinedtothislineageappearbespecified , ). Theanteriorlobedevelopsthroughexpansionof The only pituitary regulatory TFclearly showntoexert regulatory The onlypituitary Two TF’s oftheneurogenicbHLHsubfamilyexert 68 62 ) wasshownthroughitstissue-specific knockout ). Ascorticotropesandgonadotropesappearto ). PROP1directlytargetsasetofgenesinvolved 67 )) contribute to a binary switchbetween )) contributetoabinary 66 72 ). Otherlineagesappeartobespecified ). Thesefactorsmaythusplayarole H Julietteandothers 60 ). Sox2isapioneer 4 63 ). Itishowever ). WhileTpit 69 , 64 70 , , melanotrope differentiationbutnotfor ( absence ofPax7leadstodifferentiationintocorticotropes in itselfpreventdifferentiationbutTpitexpression and corticotropes ( of differentiationinbothPOMClineages,melanotropes Tpit. Whereasknockoutofthe a dayexpressionoftheterminaldifferentiationdriverTF marker expression overlapswiththeofprogenitor progenitor cellsdifferentiate,theyexpressPax7andthis the progenitor-linedlumen/cleft.Asintermediatelobe by the formation of of the developing anterior pituitary with neuraltissuesanditsisolationfromtheremainder of theintermediatelobeisuniquebyitsdirectcontact develops fromclosureofRathke’s pouch,theprimordium Rathke’s pouchderivatives( contact isasiteofintensesignaling between neuronaland throughout life.Inearlydevelopment,thispointof of ATACseq landscapesfortheselineagesaswell aswith mouse melanotropescomparedtocorticotropes( comparison of genomic accessibility profiles in normal like cells( 20, andthustransdifferentiatingthemintomelanotrope- by expressingPax7inthemodelcorticotropecelllineAtT- melanotrope-specific enhancerswereinitiallyidentified binding toabout2000enhancers( achieved throughchromatinopeningtriggeredbyPax7 Pax7 requiresitspioneeraction.Genome-widethis is The implementationofthemelanotropecellfateby not promoters expression: anaffairofenhancers, Pax7 andthemelanotropeprogramofgene antagonistic? lineage: couldthepioneeractionsofGATA2 andPax7be GATA2 expression in cells committed to the gonadotrope speculate that this incompatibility is related to early incompatible withthegonadotropefate( function transgenicexperimentwasonlyfoundtobe progenitor cellcycleexit,p57 regulate expressionofthecellcycleinhibitorthatcontrols se such as promoters and enhancers ( elements reveals accessibleDNAat activeregulatory were comparedusingthe ATACseq technique that The genomiclandscapesof thesenormalmousecells pituitary Pioneer transcriptionfactorsin 4 . ItisnonethelessinterestingthatPax7wasfoundto , 66 Overexpression of Pax7 in a pituitary-wide gain-of- Overexpression ofPax7inapituitary-wide ). Pax7 is thus the requisite binary switchfor ). Pax7isthustherequisitebinary Sox2 Fig. 2C ( 4 ). Pax7 expression precedes by about half ). Theirrelevancewasconfirmedby 64 ), the knockout of Downloaded fromBioscientifica.com at10/03/202111:46:00PM 57 Kip2 Tpit ). As the glandular pituitary ). Astheglandularpituitary ( generesultsinblockade 4 ). Fig. 2B 184 4 , :1 6 Pax7 ). Comparison ). Thissetof 4 ). We may does not R8 66 per via freeaccess ). European Journal of Endocrinology few days.Thisisthusalengthy processbycomparisonto targeted bytheseenhancers occursoverthecourseofa H3K27ac. Finally, transcriptionalactivationofthegenes the recruitmentofp300and the deposition of itsmark, transcriptional activityatthese enhancersisprovidedby of thechromatinasrevealedbyATACseq. Evidenceof This stabilisation is accompanied by progressive opening active enhancer chromatin marks such asH3K4me1. is stabilizedand this is accompanied by deposition of weak ( rapidly recruitedtothesesitesbutthisinitialbinding is not accessibletononpioneerfactorssuchasTpit.Pax7 is heterochromatin suchasH3K9me2andtheenhancersare enhancers harbours repressivemarks typical offacultative action, the chromatin of these melanotrope-specific that occuratPax7-dependentenhancers( chromatin remodelingactionofpluripotencyfactors. whether this process bears any similarity to the large-scale TAD domainsremainscompletelyelusive.Itisalsounclear responsible forthisPax7-dependentopeningofentire elements( many genesandregulatory that coverhundredsofthousandbasepairs,containing more globallytoregulatetheaccessibilityofentireTADs acts locallytoopenPax7-dependentenhancersbutalso the actionofPax7inmelanotropelineagenotonly melanotropes but not in corticotropes. This suggests that receptor 2 ( 2 ( the genesofmelanotrope-specificProteinconvertase corticotropes. Forexample,theentireTADs encompassing that exhibitmarksofactivityinmelanotropesbutnot known astopologicallyassociateddomains(TADs) ( oftenentiregenomicdomains not onlyenhancers,butvery melanotropes and corticotropes further reveals that it is differentially accessibleenhancersineachlineage( expression of these genes therefore appears todepend on of promotersareaccessibleinbothlineages.Differential corticotropes or melanotropes and for which the bulk about 250genesthatareuniquelyexpressedineither is notaccessibleinmelanotropes( accessible in corticotropes, whereas the specific regulators.Forexample,the ATAC andtheseincludethepromotersofgenesforcell- about 20promotersexhibitcell-specificaccessibilityby restricted accessibility( fewpromotersshowcell- enhancers andthatvery elements aredifferentially accessible specific regulatory revealed that cell- other cells of the mouse pituitary Review Pcsk2 We haveabetterunderstandingoflocalchanges Comparison ofthegenomiclandscapesin Fig. 1 ) aswellthatcontainingthedopamine Drd2 ). Overa period of12to24h, Pax7 binding ) gene are inactive/open conformation in 6 ). ForthePOMClineages,only H Julietteandothers 66 Pax7 ). Thiscontrastswith 66 NeuroD1 ). Themechanism promoterisnot 6 ). BeforePax7 promoter 6 , 66 73 ). ) action, andpreparetheseenhancersforfurtheractivation initial chromatinopening,thatisthehallmarkofpioneer or H3K27ac.Thisprimingprocessmayconstitutethe ATACseq/DNA accessibility signal in absenceof p300 the enhancermarkH3K4me1withlow, ifsignificant, activation ( intermediate stateintheprocessofcompleteenhancer Pax7 pioneering.Thisprimedstatemayrepresentan that switchfromaninactivetoaprimedstatefollowing act atanothersubsetabout8000putativeenhancers interesting thatinAtT-20 cells,Pax7wasalsofoundto subset.Itishowever melanotrope-specific regulatory about 2000 enhancers that constitute the bulk of the activation ofenhancersinthemodelAtT-20 cellsidentified cells and the Pax7-dependent melanotrope pituitary hours. to alreadyopenedenhancersasthisusuallyoccurswithin simple transcriptionalactivationtriggeredbyTFbinding opening initiated by Pax7 are dependent on Tpit as it is melanotrope cells,thenextstepsinenhancer pituitary relatively subtle, change in chromatin organization. In in closedheterochromatinand toinitiateaninitial,and (and presumablyotherpioneers) istorecognizetargets in thattheyindicatetheuniquepropertyofPax7 areimportant phase ofpioneeraction.Theseobservations ATACseq signals commensuratewiththeearlyorfirst Pax7 actioninTpit-deficientcellsonlyleadstomodest detected bysignificant ATACseq signalgains.Incontrast, that Tpitisrequiredforbulkchromatinopening as to theTpit-negative opening intheTpit-expressingAtT-20 cellscompared ( knockout intermediatelobesasrevealedbyATACseq and well as entire melanotrope-specific TADs (such as activity. Indeed,melanotrope-specificenhancersas of enhancersasTpitdidnotappeartohavepioneer for chromatinopeningatthemelanotroperepertoire first surprisingtorealize that bothfactors arerequired Tpit, in the process of chromatin opening ( these factors,thepioneerPax7andnonpioneer theroleofeach differentiation allowedustoquery The dependenceonbothPax7andTpitformelanotrope nonpioneer TFsPax7andTpit Cooperation betweenpioneerand through recruitmentofothernonpioneerTFs. pituitary Pioneer transcriptionfactorsin 66 ). ThereconstitutionofPax7-dependentchromatin Both thedifferentiallyaccessibleregionsinnormal Drd2 TADs) failedtoopeninboth Fig. 1 ). Itischaracterizedbythepresenceof α T3 cellssupportedtheconclusion Downloaded fromBioscientifica.com at10/03/202111:46:00PM https://eje.bioscientifica.com 184 :1 Pax7 Fig. 4 and ). It was Pcsk2 R9 Tpit via freeaccess

European Journal of Endocrinology https://eje.bioscientifica.com unresolved innature. and relativelysubtle,chromatin remodelingthatisstill targets inclosedheterochromatin andperformaninitial, Rather, theuniquepropertiesofpioneers istorecognized pioneers isnot enhanced chromatinopeningbutthecriticalaction of cancers. In conclusion, recruitment of most TFs leads to discussed below in the context of hormone-dependent dependent onpriorprimingbythepioneerFoxA:this is example, theactionofsteroidhormonereceptorsisoften TFs maybeinvolvedintheactionofotherpioneers.For in theseinstances. envisioned thatotherTFsmayfulfillasimilarroleasTpit enhancers donotshowTpitrecruitmentandhence,it is recruit Tpit in melanotrope cells, some Pax7-pioneered proportion ofPax7-dependentpioneeredenhancersalso large leading tonucleosomeeviction. Although avery remodeling complexessuchastheSwi/Snfcomplex with Pax7 ( DNA sequenceandthroughprotein/proteininteractions co-recruited tothesameenhancersthroughitscognate nonpioneer Tpitforestablishmentofthemelanotrope-specificchromatinlandscape( in intermediatelobesof knockout intermediatepituitarycellsthatcompletelyswitchtoacorticotropefateinabsenceofPax7.Analysischromatin states nonpioneer TpitfollowingPax7action( at asetofabout2000melanotrope-specificenhancersandlargeproportion(about70%)theserecruitthe abrogates thisdifferentiation( development, thenonpioneerTFTpitdeterminescorticotropecellfateinanteriorpituitaryandknockoutof Cooperation betweenthepioneerPax7andnonpioneerTpitforestablishmentofmelanotropecellfate.Innormal Figure 4 Review Similar relationshipsbetweenpioneerandnonpioneer 4 , 66 per se ). This involves recruitment of chromatin linkedtobulkchromatinopening. Pax7 and 64 ). Intheintermediatepituitary,expressionofpioneerPax7isrequiredforchromatinopening Tpit H Julietteandothers knockoutpituitariesshowedtheessentialcooperationbetweenpioneerPax7and 4 , 6 ). TheessentialroleofPax7pioneeringissupportedbythephenotype proliferation anddifferentiation( cells, have unique pathways controlling self-renewal, of pluripotency( Sox2 is critical for stem cell renewal and maintenance others maintainthestemcellstate.Thepluripotencyfactor or precisemechanismsaremostlylacking. of pioneersintumorigenesisseemsclear, causativelinks hormone-dependent cancers( Pax7/Pax3 inrhabdomyosarcomas ( proliferation andanchorage-independent growth( vitro expression ofSox2increases tumorcellself-renewal esophageal squamouscell carcinomas whereasectopic increased levels of Sox2 protein was found in ~20% of lung Sox2, genomicamplificationofthe to cancers,suchasSox2insquamouscellcancers( has direconsequences.Infact,manypioneerswerelinked fates andgene expression programs, their dysregulation As thenormalfunctionofpioneersistoimplementnewcell Pioneers intumorigenesis pituitary Pioneer transcriptionfactorsin Some pioneersregulatecelldifferentiationwhile , andknockdownofSox2expression decreasestumor 66 77 ). ). Stemcells,aswellcancerstem Downloaded fromBioscientifica.com at10/03/202111:46:00PM 76 ). Whiletheimplication 78 Sox2 184 75 ). With regardsto ), andFoxA1in :1 geneleadingto Tpit Pax7 gene R10

74 74 via freeaccess in ), , European Journal of Endocrinology receptor (AR). ERand AR activate the transcription of receptors, namelyestrogen receptor(ER)andandrogen cancers ( prostate cancers,aresome ofthemostpreponderant invasion ( terminal differentiation and promotescell migration and blocks stimulates cellproliferation,promotessurvival, patients) ( rhabdomyosarcomas (15%and52%respectivelyinolder transactivation domainofFOXO1inamajorityalveolar DNA binding domains of Pax7 or Pax3 fused to the related Pax3( chromosomal translocationsinvolvingPax7orthe positive forPax7( rhabdomyosarcomasfound that 83% ofembryonal are Pax7 isexpressedinmostrhabdomyosarcomas: onestudy may, therefore,promotetumorigenesis( blocked ( cells enterterminaldifferentiationandthecellcycleis allowing long-termmusclerenewal( andblockingcelldifferentiation, promoting cellsurvival injury. Pax7isrequiredtomaintainthesatellitecellpoolby muscle stemcellsthatareactivatedinresponseto in adultmusclesatellitecells( for myogenicdevelopmentanditsexpressionismaintained tumors, ithasinmyogenictumors.Indeed,Pax7iscritical type 4(MEN4)syndrome( p27 Pax7 involvementintheseadenomas.Mutationsofthe tumor development( and knockout of the adenomas,inparticularCushing’s,lost inmanypituitary Sox2 repression by p27 expression. Thisswitchmaybethedirectconsequenceof ( fromp57 the controlofcellcyclere-entry changes ingeneexpression( development and this isaccompanied by widespread development( hypothalamo-pituitary development. However, rare tumor its (mis)expression is not associated with pituitary progenitors, spite ofSox2expressionmarkingpituitary poor outcome,thismaynotbetrueinallcases( the ideathathighSox2expressionmaycorrelatewith growth initiation( 79 4 Review , ). Further, 84 Kip1 Hormone-dependent cancers, including breast and Further, many rhabdomyosarcomas have While Pax7hasnotyetbeeninvolvedinpituitary Pax7 specifiesthemelanotropefateduringpituitary ) inparallelwiththeswitchbetween geneitselfcausethemultipleendocrineneoplasia 91 97 96 95 ). AbnormaloruntimelyexpressionofPax7 ). Mostaredrivenbynuclear hormone ). ). ThesetranslocationscreateanewTFthat in vivo 94 93 ). Thesetranslocationsinvolvethe knockdown of Sox2 prevented tumor 80 ). p27 , 86 Kip1 81 Kip1 ), thereisasyetnoevidenceof ( ). Whilethesestudiessupport 87 85 gene in mice leads to pituitary gene in miceleadsto pituitary , ). While p27 Sox2 88 66 89 ). ), includingaswitchin H Julietteandothers ). Satellitecellsareadult genemutationsaffect 90 83 ). Without Pax7, ). 92 Kip1 ). Andindeed, Sox2 Kip2 expression is top27 and 82 Pax7 ). Kip1

to their target sites and enhance gene transcription ( GATA TFs appear to cooperate with FoxA1 to recruit ER/AR are also often enriched in GATA motifs. Thus, pioneer binding toenhancersequences( also requiredforhormonereceptoractivity, enablingtheir pancreas, liverandlungdifferentiation( gland, pioneer factors driving notablyprostate, mammary family, containingFoxA1,FoxA2andFoxA3,thatare activity, respectively ( and FoxA1-GATA3 inregulatingARandERtranscriptional identified, includingthesignificantroleofFoxA1-GATA2 by whichthesetumorsgrow, andprogresshavebeen natural ligand.Inthelastdecade,somemechanisms breast- andprostate-specific genesuponbindingoftheir and the gene itself is mutated in about 1.8% of breast found inseveralcancersleadingtoFoxA1overexpression, Nonetheless, genomicamplificationoftheFoxA1locusis hormone-dependent cancersstillrequireclarifications. The specificmechanismslinkingFoxA1,GATA TFsand EBP suppressor becauseloss-of-functionmutationsinthe myeloid lineages( differentiation andinducescellcyclearrestinseveral to belinkedendocrinetherapyresistance( overexpression is linked to poor prognosis and it appears cancer and3to5%inprostate( contributions andcommentsonthe manuscript. their for laboratory the of colleagues many to indebted are authors The Acknowledgements grant oftheCanadianInstitutesHealth Research. Work performed in the author’s laboratory was supported by a Foundation Funding be could that interest of conflict perceived asprejudicingtheimpartialityofthisreview. no is there that declare authors The Declaration ofinterest their damagingeffectsincancer. normal developmentinordertocomprehendandmaster pathways in their pleiotropicactionsongeneregulatory hence, weneedtounderstandthemechanismsunderlying pivotal rolesasmasterregulatorsofbasiccellfunctions: cancer development.ThesecriticalanduniqueTFshave pathways, pioneermisexpressionisoftenassociatedwith differentiation orbydirectlyregulatingcellgrowth cases. (AML) and pituitary Pioneer transcriptionfactorsin α In summary, whether it is indirectly by promoting Another pioneerfactor, C/EBP genetriggerdevelopmentofacutemyeloidleukemia C/EBP α 104 geneactivityislostin~10%ofAML ). Itwassuggestedtoactasatumor 98 Downloaded fromBioscientifica.com at10/03/202111:46:00PM ). FoxA1 is part of the FoxA https://eje.bioscientifica.com 100 α , , drivesmyeloidcells 101 184 76 :1 , ). Further, FoxA1 1 102 , 99 ). Thesesites 103 ). FoxA1is ). R11 98 via freeaccess C/ ). European Journal of Endocrinology https://eje.bioscientifica.com References 16 15 14 13 12 11 10 9 8 6 5 4 3 2 1 7 Review Vierbuchen T, Ling E,Cowley CJ,Couch CH, Wang X, Harmin DA, Takaku M, Grimm SA,Shimbo T, Perera L,Menafra R, Hublitz P, Albert M,Peters AH,Hublitz P, Albert M& Peters AHFM. Schuettengruber B, Bourbon HM,DiCroce L&Cavalli G.Genome Buenrostro JD, Giresi PG,Zaba LC,Chang HY&Greenleaf WJ. Nicetto D, Donahue G,Jain T, Peng T, Sidoli S,Sheng L,Montavon T, Soufi A, Donahue G&Zaret KS.Facilitatorsandimpedimentsof Donaghey J, Thakurela S, Charlton J, Chen JS, Smith ZD, Gu H, Pop R, Calo E &Wysocka J. Modificationofenhancerchromatin:what, Mikkelsen TS, Ku M,Jaffe DB,Issac B,Lieberman E,Giannoukos G, Mayran A, Khetchoumian K,Hariri F, Pastinen T, Gauthier Y, Pelletier A, Mayran A,Omichinski J&Drouin J.Pax7pioneeraction Balsalobre A,Gauthier Y,Budry L, Khetchoumian K,L’Honore A, Soufi A, Garcia MF, Jaroszewicz A,Osman N,Pellegrini M& Mayran A, Pelletier A&Drouin J.Paxfactorsintranscriptionand Zaret KS &Carroll JS.Pioneertranscriptionfactors:establishing molcel.2017.11.026) Cell BAF complexmediatesignal-dependent enhancerselection. Roberts CWM &Greenberg ME.AP-1 transcriptionfactorsandthe Biology domain dependentrecruitmentofachromatinremodeler. GATA3-dependent cellularreprogramming requiresactivation- Stunnenberg HG, Archer TK, Machida S,Kurumizaka H&Wade PA. 335–354. methylation. Mechanisms oftranscriptionalrepressionbyhistonelysine 2017 regulation byPolycombandtrithorax:70yearscounting. org/10.1038/nmeth.2688) position. profiling ofopenchromatin,DNA-bindingproteinsandnucleosome Transposition ofnativechromatinforfastandsensitiveepigenomic science.aau0583) specification. loss atprotein-codinggenesenablesdevelopmentallineage Becker JS, Grindheim JM,Blahnik K cell.2012.09.045) the genome. the pluripotencyreprogrammingfactors’initialengagementwith org/10.1016/j.molcel.2013.01.038) how, andwhy? 2007 of chromatinstateinpluripotentandlineage-committedcells. Alvarez P, Brockman W, Kim TK,Koche RP 50 epigenetic effectsofpioneer-factoroccupancy. Clement K, Stamenova EK,Karnik R 50 enhancer repertoireforspecificationofcellfate. Balsalobre A &Drouin J.PioneerfactorPax7deploysastable 2020. requires bothpairedandhomeoDNAbindingdomains. 2299–2310. action onchromatinremodeling. cellfatesthroughitspioneer gene Pax7dictatesalternatepituitary Vallette S, Brue T, Figarella-Branger D,Meij B&Drouin J.Theselector (https://doi.org/10.1016/j.cell.2015.03.017) nucleosomes toinitiatereprogramming. Zaret KS. PioneertranscriptionfactorstargetpartialDNAmotifson 2015 epigenetic remodelling. 2227–2241. competence forgeneexpression. 250–258. 259–269. 2017 171 448 44 (https://doi.org/10.1101/2020.10.09.332015) 2016 135–144. Nature Methods 34–57. 553–560. (https://doi.org/10.1387/ijdb.082717ph) 68 (https://doi.org/10.1101/gad.200436.112) (https://doi.org/10.1101/gad.176826.111) 1067.e12–1082.e12. (https://doi.org/10.1038/s41588-017-0034-3) 17 (https://doi.org/10.1038/s41588-017-0035-2) Cell International Journal ofDevelopmentalBiology Journal International Science 36. Molecular Cell 2012 (https://doi.org/10.1016/j.cell.2017.08.002) (https://doi.org/10.1016/j.semcdb.2015.07.007) (https://doi.org/10.1038/nature06008) (https://doi.org/10.1186/s13059-016-0897-0) 2019 151 Seminars inCellandDevelopmentalBiology 2013 363 994–1004. 2013 10 294–297. 1213–1218. Genes andDevelopment (https://doi.org/10.1016/j. Genes andDevelopment 49 et al et al H Julietteandothers 825–837. (https://doi.org/10.1016/j. . Genetic determinants and . Geneticdeterminantsand . H3K9me3-heterochromatin Cell (https://doi.org/10.1126/ et al 2015 (https://doi. Nature Genetics . Genome-widemaps (https://doi. Nature Genetics 161 555–568. 2011 2012 BioRxiv 2009 Genome Molecular 2018 2018 25 26 Cell Nature 2018 53

pituitary Pioneer transcriptionfactorsin 23 30 29 28 27 26 25 24 22 21 20 19 18 17 32 31 Cirillo LA, Lin FR,Cuesta I,Friedman D,Jarnik M&Zaret KS. Li S, Zheng EB,Zhao L&Liu S.Nonreciprocalandconditional Iwafuchi-Doi M, Donahue G,Kakumanu A,Watts JA, Mahony S, Cirillo LA, McPherson CE,Bossard P, Stevens K,Cherian S,Shim EY, Fernandez Garcia M, Moore CD,Schulz KN,Alberto O,Donague G, McDaniel SL, Gibson TJ,Schulz KN,FernandezGarcia M, Nevil M, Laptenko O, Beckerman R,Freulich E&Prives C.p53bindingto Cirillo LA &Zaret KS.Anearlydevelopmentaltranscriptionfactor Thurman RE, Rynes E,Humbert R,Vierstra J, Maurano MT, Larson AG, Elnatan D,Keenen MM,Trnka MJ, Johnston JB, Jang SM, Kauzlaric A,Quivy JP, Pontis J,Rauwel B,Coluccio A, Canzio D, Larson A&Narlikar GJ.Mechanismsoffunctional Fyodorov DV, Zhou BR,Skoultchi AI&Bai Y. Emergingrolesof King HW &Klose RJ.ThepioneerfactorOCT4requiresthe Michael AK, Grand RS,Isbel L,Cavadini S, Kozicka Z,Kempf G, Dodonova SO, Zhu F, Dienemann C,Taipale J &Cramer P. 489 accessible chromatinlandscapeofthehumangenome. doi.org/10.1016/j.celrep.2019.07.103) transcription factors. cooperativity directsthepioneeractivityofpluripotency 79–91. enhancers fortissue-specificgeneactivation. factor FoxAmaintainsanaccessiblenucleosomeconfigurationat Pugh BF, Lee D,Kaestner KH&Zaret KS.ThePioneertranscription emboj/17.1.244) EMBO Journal transcription factorHNF3toalinkerhistonesiteonthenucleosome. Clark KL, Burley SK&Zaret KS.Bindingofthewinged-helix 921.e6–932.e6. factors associatingwithnucleosomebinding. Harrison MM, Zhu H&Zaret KS.Structuralfeaturesoftranscription org/10.1016/j.molcel.2019.01.014) activation. of thepioneerfactorZeldaisrequiredtodrivezygoticgenome Jain SU, Lewis PW, Zaret KS&Harrison MM.Continuedactivity (https://doi.org/10.1073/pnas.1105680108) loss andtranscriptionalactivation. nucleosomes withinthep21promoterinvivoleadstonucleosome S1097-2765(00)80225-7) free DNA. complex thatismorestableonnucleosomecoreparticlesthan 279–289. transcription factorsHNF3(FoxA)andGATA-4. Opening ofcompactedchromatinbyearlydevelopmental Haugen E, Sheffield NC,Stergachis AB, Wang H, Vernot B org/10.1038/nature22822) in heterochromatin. droplet formationbyHP1 Burlingame AL, Agard DA,Redding S&Narlikar GJ.Liquid gky580) Acids Research reinstatement ofheterochromatinafterDNAreplication. Offner S, Duc J,Turelli P, Almouzni G (https://doi.org/10.1016/j.tcb.2014.01.002) promiscuity byHP1proteins. org/10.1038/nrm.2017.94) Nature ReviewsMolecularCellBiology linker histonesinregulatingchromatinstructureandfunction. (https://doi.org/10.7554/eLife.22631) stemcells. function inmouseembryonic element chromatin remodellerBRG1tosupportgeneregulatory Bunker RD, Schenk AD,Graff-Meyer A, Pathare GR s41586-020-2195-y) factor function. Nucleosome-bound SOX2andSOX11 structureselucidatepioneer 75–82. (https://doi.org/10.1016/j.molcel.2016.03.001) (https://doi.org/10.1016/S1097-2765(02)00459-8) Molecular Cell Molecular Cell (https://doi.org/10.1038/nature11232) 1998 2018 (https://doi.org/10.1016/j.molcel.2019.06.009) Nature 17 46 Nature Cell Reports 244–254. 8788–8802. 2020 1999 2019 α Downloaded fromBioscientifica.com at10/03/202111:46:00PM suggestsaroleforphaseseparation 2017 580 Trends inCellBiology 4 74 961–969. 2019 (https://doi.org/10.1093/ 669–672. 547 185.e4–195.e4. (https://doi.org/10.1093/nar/ PNAS 2018 236–240. et al 28 2011 2689.e4–2703.e4. eLife (https://doi.org/10.1016/ 19 . KAP1facilitates (https://doi.org/10.1038/ 184 192–206. Molecular Cell Molecular Cell 2017 108 :1 (https://doi. Molecular Cell (https://doi. 2014 10385–10390. et al 6 22631. (https://doi. . Mechanisms Nature 24 Nucleic et al 2016 377–386. 2019 (https:// 2002 2012 . The R12 62 75 via freeaccess

European Journal of Endocrinology

37 49 48 47 46 45 44 43 42 41 40 39 36 35 34 33 38 Review Mivelaz M, Cao AM,Kubik S,Zencir S,Hovius R,Boichenko I, Jones PA &Takai D. TheroleofDNAmethylationinmammalian Jabbari K &Bernardi G.Cytosinemethylation andCpG,TpG Suzuki MM &Bird A.DNAmethylationlandscapes:provocative Nan X, Ng HH,Johnson CA,Laherty CD,Turner BM, Eisenman RN Xie S &Qian C.ThegrowingcomplexityofUHRF1-mediated Escobar TM, Oksuz O,Saldaña-Meyer R,Descostes N,Bonasio R& Deluz C, Friman ET, Strebinger D,Benke A,Raccaud M,Callegari A, Kadauke S, Udugama MI, Pawlicki JM, Achtman JC, Jain DP, Cheng Y, Caravaca JM, Donahue G,Becker JS,He X,Vinson C &Zaret KS. &Groth A.Chromatinreplication Stewart-Morgan KR, Petryk N Liu Z &Kraus WL.Catalytic-independentfunctionsofPARP-1 Iwafuchi M, Cuesta I,Donahue G,Takenaka N, Osipovich AB, Li G, Levitus M,Bustamante C&Widom J. Rapidspontaneous Polach KJ &Widom J. MechanismofproteinaccesstospecificDNA Minderjahn J, Schmidt A,Fuchs A,Schill R,Raithel J,Babina M, Yu X &Buck MJ.DefiningTP53pioneeringcapabilitieswith science.1063852) epigenetics. org/10.1016/j.gene.2004.02.043) (CpA) andTpAfrequencies. (https://doi.org/10.1038/nrg2341) insights fromepigenomics. 393 protein MeCP2involvesahistonedeacetylasecomplex. & Bird A.Transcriptional repression bythemethyl-CpG-binding org/10.3390/genes9120600) maintenance DNAmethylation. 953–963.e11. nucleosome segregationduringDNAreplication. Reinberg D. Activeandrepressedchromatindomainsexhibitdistinct 2016 SOX2 inpluripotencyanddifferentiation. Leleu M, Manley S&Suter DM.Aroleformitoticbookmarkingof (https://doi.org/10.1016/j.cell.2012.06.038) hematopoietic transcriptionfactorGATA1. Hardison RC &Blobel GA.Tissue-specific mitoticbookmarkingby 251–260. factor tomitoticchromosomes. Bookmarking byspecificandnonspecificbindingofFoxA1pioneer (https://doi.org/10.1038/s41556-020-0487-y) and epigeneticcellmemory. molcel.2017.01.017) Molecular Cell determine Sox2pioneeractivityatintractablegenomicloci. 52 pioneer transcriptionfactorandcorehistones. dependuponinteractionsbetweena network transitionsinembryos Magnuson MA, Roder H,Seeholzer SH,Santisteban P&Zaret KS.Gene org/10.1016/j.molcel.2019.10.025) factor. invasion andnucleosomedisplacementbytheRap1transcription Stachowicz AM, Kurat CF, Shore D&Fierz B.Chromatinfiber Biology accessibility ofnucleosomalDNA. doi.org/10.1006/jmbi.1995.0606) regulation. sequences inchromatin:adynamicequilibriummodelforgene doi.org/10.1038/s41467-019-13960-2) classical pioneerPU.1. governing thepioneeringandredistributioncapabilitiesofnon- Schmidl C, Gebhard C,Schmidhofer S,Mendes K 107–115. competitive nucleosomebindingassays. 1460–1465. of OCT4-SOX2motifreadoutonnucleosomes. 418–427. 386–389. 30 2005 Molecular Cell 2538–2550. (https://doi.org/10.1101/gad.206458.112) (https://doi.org/10.1101/gr.234104.117) Journal ofMolecularBiology Journal (https://doi.org/10.1126/science.abb0074) Science (https://doi.org/10.1038/s41588-020-0591-8) 12 2017 (https://doi.org/10.1016/j.cell.2019.10.009) (https://doi.org/10.1038/30764) 46–53. 2001 65 2020 (https://doi.org/10.1101/gad.289256.116) 589.e9–603.e9. Nature Communications (https://doi.org/10.1038/nsmb869) 293 77 Nature ReviewsGenetics Gene Nature CellBiology 1068–1070. 488.e9–500.e9. Genes andDevelopment Genes 2004 Nature Structural andMolecular Nature Structural H Julietteandothers 1995 2018 (https://doi.org/10.1016/j. 333 Genome Research (https://doi.org/10.1126/ Genes andDevelopment 143–149. Cell 254 9 (https://doi. 2020 600. Nature Genetics 2020 2012 Science 130–149. Cell et al 2008 (https://doi. 11 22 2019 150 (https://doi. 2020 . Mechanisms 2013 402. 361–371. Nature 9 2019 725–737. 465–476. (https:// 179 368 (https:// 27 2020 2020 1998 29

pituitary Pioneer transcriptionfactorsin 54 56 55 53 52 51 50 65 64 63 62 61 60 59 58 57 Sardina JL, Collombet S,Tian TV, Gómez A,DiStefano B, Jaenisch R. DNAmethylationandimprinting:whybother? Ziller MJ, Ortega JA,Quinlan KA,Santos DP, Gu H,Martin EJ, Zhou D &Robertson KD.RoleofDNAmethylationingenome Okano M, Bell DW, Haber DA&Li E.DNAmethyltransferases Li E &Zhang Y. DNAmethylationinmammals. Saxonov S, Berg P&Brutlag DL.Agenome-wideanalysisofCpG Pulichino A-M, Vallette-Kasic S, Couture C, Gauthier Y, Brue T, Pulichino A-M, Vallette-Kasic S, Tsai JP, Couture C,Gauthier Y Lamolet B, Pulichino AM,Lamonerie T, Gauthier Y, Brue T, Pérez Millán MI,Brinkmeier ML,Mortensen AH&Camper SA. Goldsmith S, Lovell-Badge R&Rizzoti K.SOX2issequentially Fauquier T, Rizzoti K,Dattani M,Lovell-Badge R&Robinson ICAF. Lamonerie T, Tremblay JJ, Lanctôt C,Therrien M,Gauthier Y& Charles MA, Suh H,Hjalt TA, Drouin J,Camper SA &Gage PJ.PITX development.In Drouin J. Chapter1–Pituitary Gut M Berenguer C, Brumbaugh J,Stadhouders R,Segura-Morales C, 9525(97)01180-3) in Genetics stem.2018.02.012) Stem Cell in humanmotorneurondifferentiationandphysiology. functional consequencesofdenovoDNAmethylationdynamics Galonska C, Pop R,Maidl S,DiPardo A org/10.1016/B978-0-12-803309-8.00024-0) stability. In org/10.1016/S0092-8674(00)81656-6) mammalian development. Dnmt3a andDnmt3bareessentialfordenovomethylation cshperspect.a019133) Perspectives inBiology org/10.1073/pnas.0510310103) classes ofpromoters. dinucleotides inthehumangenomedistinguishestwodistinct org/10.1101/gad.1065603) deficiency. ACTH and mouseTpitgenemutationscause earlyonsetpituitary David M, Malpuech G,Deal C,Van Vliet G,DeVroede M. Human org/10.1101/gad.1065703) differentiation. cell & Drouin J.Tpitdeterminesalternatefatesduringpituitary S0092-8674(01)00282-3) homeoproteins. Tpit, activatesPOMCtranscriptionincooperationwithPitx cell-restrictedT-boxEnjalbert A &Drouin J.Apituitary factor, eLife.14470) stemcells. pituitary PROP1 triggersepithelial-mesenchymaltransition-likeprocessin org/10.1242/dev.137984) developing pituitary. required forprogenitorproliferationandlineagespecificationinthe (https://doi.org/10.1073/pnas.0707886105) gland. in theadultmousepituitary SOX2-expressing progenitorcellsgenerateallofthemajorcelltypes gad.10.10.1284) Genes andDevelopment involved intranscriptionofpro-opiomelanocortin(POMC)gene. Drouin J. PTX1,a 0052) Endocrinology and genes arerequiredforcellsurvival org/10.1016/B978-0-12-804169-7.00001-5) ed., pp.3–22.EdSMelmed.AcademicPress,2017. e729–741.e729. demethylation toreprogramcellfate. et al 2018 1997 . Transcription factorsdriveTet2-mediated enhancer Genes andDevelopment Genome Stability 2005 22 Genes andDevelopment (https://doi.org/10.1016/j.stem.2018.08.016) 13 Cell 559.e9–574.e9. bicoid- 323–329. 19 2001 eLife 2014 PNAS Development 1893–1903. 1996 related homeoboxtranscriptionfactor 2016 104 2006 Downloaded fromBioscientifica.com at10/03/202111:46:00PM 6 Cell , pp.409–424.Elsevier, 2016. a019133. 10 (https://doi.org/10.1016/S0168- 849–859. 5 1999 1284–1295. e14470. 103 2016 2003 (https://doi.org/10.1016/j. (https://doi.org/10.1210/me.2005- PNAS https://eje.bioscientifica.com 1412–1417. 99 Cell Stem 2003 (https://doi.org/10.1101/ Lhx3 143 247–257. 17 et al (https://doi.org/10.1016/ 2008 (https://doi.org/10.7554/ 711–716. 184 2376–2388. activation. (https://doi.org/10.1101/ 17 . Dissectingthe 738–747. 105 :1 Cold SpringHarbor The Pituitary (https://doi. (https://doi. (https://doi. 2018 2907–2912. (https://doi. Molecular (https://doi. (https://doi. 23 Cell (https://doi. Trends 727. , 4th R13 via freeaccess European Journal of Endocrinology https://eje.bioscientifica.com

81 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 Review Santini R, Pietrobono S,Pandolfi S, Montagnani V, D’Amico M, Laga AC, Lai C-Y, Zhan Q,Huang SJ,Velazquez EF, Yang Q, Hsu M-Y Hussenet T, Dali S,Exinger J,Monga B,Jost B,Dembelé D, Bonnet D &Dick JE.Humanacutemyeloidleukemiaisorganized Avilion AA. Multipotentcelllineagesinearlymousedevelopment Robinson JLL &Carroll JS.FoxA1isakeymediatorofhormonal Tenente IM, Hayes MN,Ignatius MS,McCarthy K,Yohe M, Bass AJ, Watanabe H, Mermel CH, Yu S, Perner S,Verhaak RG, Szabo Q, Bantignies F&Cavalli G.Principlesofgenomefolding Zhang F, Tanasa B, Merkurjev D,Lin C,Song X,Li W, Tan Y, Wapinski OL, Lee QY, Chen AC,Li R,Corces MR, Ang CE, Vierbuchen T, Ostermeier A,Pang ZP, Kokubu Y, Sudhof TC& Pataskar A, Jung J,Smialowski P, Noack F, Calegari F, Straub T& Dasen JS, O’Connell SM,Flynn SE,Treier M, Gleiberman AS, Charles MA, Saunders TL,Wood WM, Owens K,Parlow AF, Mayran A, Sochodolsky K,Khetchoumian K,Harris J,Gauthier Y, Penachioni JY, Vinci MC, Borgognoni L&Stecca B.SOX2 regulates 903–913. factor SOX2inhumanskin. & Murphy GF. stemcelltranscription Expression oftheembryonic org/10.1371/journal.pone.0008960) lung squamouscellcarcinomas. oncogene activatedbyrecurrent3q26.3amplificationsinhuman Martinet N, Thibault C,Huelsken J,Brambilla E 730) Nature Medicine as ahierarchy thatoriginatesfromaprimitivehematopoieticcell. (https://doi.org/10.1101/gad.224503) depend onSOX2function. 3 response inbreastandprostatecancer. eLife.19214) rhabdomyosarcoma. transcriptionfactorsregulategrowthin Myogenic regulatory Oliveira ML,Ramakrishnan A,Tang QSindiri S, Gryder B, org/10.1038/ng.465) carcinomas. oncogeneinlungandesophagealsquamouscell lineage-survival Kim SY, Wardwell L, Tamayo P, Gat-Viks I eaaw1668. into topologicallyassociatingdomains. 1380–1385. corticotrope promoter-pausingrepressionprogram. Liu Z, Zhang J,Ohgi KA celrep.2017.09.011) Cell Reports switch inthedirectreprogrammingoffibroblaststoneurons. Treutlein B, Xiang C,Baubet V, Suchy FP org/10.1038/nature08797) by definedfactors. Wernig M. Directconversionoffibroblaststofunctionalneurons 24–45. landscapes toinducetheneuronalprogram. Tiwari VK. NeuroD1reprogramschromatinandtranscriptionfactor doi.org/10.1016/S0092-8674(00)80770-9) celltypes. determination ofpituitary interactions ofPit1andGATA2 mediatesignalinggradient-induced Szeto DP, Hooshmand F, &Rosenfeld MG.Reciprocal Aggarwal AK 0378) Endocrinology knockout: effectsongonadotropeandthyrotropefunction. Camper SA, Ridgway EC&Gordon DF. Gata2 Pituitary-specific 11791-9) Communications cooperation driveslineagespecificchromatinopening. Bemmo A, Balsalobre A&Drouin J.Pioneerandnonpioneerfactor . (https://doi.org/10.3389/fendo.2012.00068) (https://doi.org/10.15252/embj.201591206) (https://doi.org/10.2353/ajpath.2010.090495) 2017 (https://doi.org/10.1126/sciadv.aaw1668) (https://doi.org/10.1073/pnas.1424228112) Nature Genetics 2006 1997 2019 20 Nature 20 3236–3247. eLife 3 1366–1377. 10 730–737. et al 3807. 2010 2017 2009 Genes andDevelopment . Enhancer-boundLDB1regulatesa American Journal ofPathology American Journal 463 (https://doi.org/10.1038/s41467-019- 6 PLoS ONE (https://doi.org/10.1016/j. e19214. (https://doi.org/10.1038/nm0797- 41 (https://doi.org/10.1210/me.2005- 1035–1041. 1238–1242. Cell H Julietteandothers Frontiers inEndocrinology Science Advances et al 1999 et al 2010 (https://doi.org/10.7554/ EMBO Journal . Rapidchromatin . SOX2isanamplified 97 et al 5 (https://doi. (https://doi. e8960. 2003 587–598. PNAS . SOX2isan Nature 2019 17 2010 2015 (https://doi. 2016 et al 126–140. Molecular (https:// 5 . 176

2012 112 35

pituitary Pioneer transcriptionfactorsin 86 85 84 83 82 95 94 93 92 91 90 89 88 87 Roussel-Gervais A, Bilodeau S,Vallette S,Roussel-Gervais A, Berthelet F, Lacroix A, Li H, Collado M,Villasante A, Matheu A,Lynch CJ, Canamero M, &Drouin J.Distinctdevelopmental Bilodeau S, Roussel-Gervais A Kelberman D, Rizzoti K, Avilion AA, Bitner-Glindzicz M, Cianfarani S, Bayo P, Jou A,Stenzinger A,Shao C,Gross M,Jensen A,Grabe N, Dumont SN, Lazar AJ,Bridge JA,Benjamin RS &Trent JC. PAX3/7– Linardic CM. PAX3–FOXO1 fusion gene inrhabdomyosarcoma. Charville GW, Varma S, Forgó E,Dumont SN,Zambrano E,Trent JC, Riuzzi F, Sorci G, Sagheddu R,Sidoni A,Alaggio R,Ninfo V& Von Maltzahn J,Jones AE,Parks RJ&Rudnicki MA.Pax7is Oustanina S, Hause G&Braun T. Pax7directspostnatalrenewaland networks and Buckingham M &Rigby PJ.Generegulatory Chasseloup F, Pankratz N,Lane J,Faucz FR,Keil MF, Chittiboina P, Marinoni I, Lee M,Mountford S,Perren A,Bravi I,Jennen L, 2010 Figarella-Branger D, Brue T&Drouin J.Cooperationbetweencyclin Cell stemcelldifferentiation. represses Sox2duringembryonic Rizzoti K, Carneiro C,Martinez G,Vidal A (https://doi.org/10.1128/MCB.01885-08) differentiated cells. of progenitorcellcycleexitfromre-entry pituitary roles ofcellcycleinhibitorsp57Kip2andp27Kip1distinguish JCI28658) Clinical Investigation axisinmiceandhumans. hypothalamo-pituitary-gonadal within Sox2/SOX2areassociatedwithabnormalitiesinthe Chong WK, Kirk JM,Achermann JC,Ross R,Carmignac D.Mutations molonc.2015.05.006) Molecular Oncology ofheadandnecksquamouscellcarcinoma.risk factorforsurvival cell motilityviavimentinup-regulationandisanunfavorable Mende CH, Rados PV, Debus J onc.2014.71) cells. self-renewal andtumorigenicityofhumanmelanoma-initiating by fluorescentinsituhybridization. FOXO1 fusionstatusinolderrhabdomyosarcoma patient population canlet.2008.03.035) Cancer Letters doi.org/10.1097/PAS.0000000000000717) ofSurgicalPathology American Journal related softtissuetumors,andsmallroundbluecellneoplasms. Lazar AJ &Van DeRijn M.PAX7 expressioninrhabdomyosarcoma, jcs.136259) of CellScience causes upregulationofPAX7 anduncontrolledproliferation. Donato R. RAGEsignalingdeficiencyinrhabdomyosarcoma cells pnas.1307680110) muscle. critical forthenormalfunctionofsatellitecellsinadultskeletal sj.emboj.7600346) EMBO Journal propagation ofmyogenicsatellitecellsbutnottheirspecification. Cell transcriptional mechanismsthatcontrolmyogenesis. clinem/dgaa160) and Metabolism with orwithoutanMEN4phenotype. CDKN1B loss-of-functionvariantscausepediatricCushing’s disease Kay DM, HusseinTayeb T, Stratakis CA,Mills JL 2990.2012.01278.x) Neurobiology tumours. of MENX-associatedpituitary Feuchtinger A, Drouin J,Roncaroli F&Pellegata NS.Characterization tumorigenesis. E andp27Kip1inpituitary 2012 2014 24 Oncogene PNAS 1835–1845. 11 28 2013 845–852. 225–238. 2008 2014 2004 2013 2014 2020 39 2015 270 127 23 Molecular andCellularBiology 110 2006 33 256–269. (https://doi.org/10.1210/me.2010-0091) 105 3430–3439. (https://doi.org/10.1016/j.stem.2012.09.014) (https://doi.org/10.1016/j.devcel.2013.12.020) 4697–4708. 10–18. 1699–1711. 16474–16479. 9 1983–2005. 1704–1719. 116 Downloaded fromBioscientifica.com at10/03/202111:46:00PM 2445–2455. et al (https://doi.org/10.1016/j. (https://doi.org/10.1111/j.1365- . LossofSOX2expressioninduces (https://doi.org/10.1038/ (https://doi.org/10.1242/ (https://doi.org/10.1038/ 2016 Journal ofCancerResearchJournal and (https://doi.org/10.1210/ Journal ofClinicalEndocrinology Journal (https://doi.org/10.1016/j. (https://doi.org/10.1073/ Neuropathology andApplied 40 Molecular Endocrinology et al (https://doi.org/10.1172/ 184 1305–1315. . p27(Kip1)directly :1 et al 2009 . Germline Developmental 29 1895–1908. (https:// Journal of Journal Cell Stem Journal Journal R14 via freeaccess European Journal of Endocrinology 100 99 98 97 96 Review Carroll JS, Liu XS,Brodsky AS,Li W, Eeckhoute J, Meyer CA,Szary AJ, Friedman JR &Kaestner KH.TheFoxafamilyoftranscriptionfactors Hankey W, Chen Z&Wang Q. Shapingchromatinstatesinprostate Ulm M, Ramesh AV, McNamara KM,Ponnusamy S,Sasano H& Margue CM, Bernasconi M,Barr FG&Schäfer BW. Transcriptional mapping ofestrogenreceptorbindingrevealslong-rangeregulation Shao W, Hestermann EV, Geistlinger TR 2006 in developmentandmetabolism. 2427–2436. cancer bypioneertranscriptionfactors. 2019 focus onprostate,breastandovariancancers. Narayanan R. Therapeuticadvancesinhormone-dependentcancers: 2921–2929. box transcriptionfactorsPAX3 andPAX3/FKHR. modulation oftheanti-apoptoticproteinBCL-XLbypaired s00432-011-1089-7) Clinical Oncology 63 8 R10–R26. 2317–2328. (https://doi.org/10.1158/0008-5472.CAN-19-3447) (https://doi.org/10.1038/sj.onc.1203607) 2012 (https://doi.org/10.1530/EC-18-0425) (https://doi.org/10.1007/s00018-006-6095-6) 138 213–220. Cellular andMolecularLifeSciences (https://doi.org/10.1007/ H Julietteandothers Cancer Research et al . Chromosome-wide Endocrine Connections Oncogene 2020 2000 80

Accepted 14October2020 Revised versionreceived2October2020 Received 30July2020 104 103 102 101 pituitary Pioneer transcriptionfactorsin Lourenço AR &Coffer PJ.AtumorsuppressorroleforC/EBP Fu X, Jeselsohn R,Pereira R,Hollingsworth EF, Creighton CJ, Lupien M, Eeckhoute J,Meyer CA,Wang Q, Zhang Y, Li W, Laganiere J, Deblois G,Lefebvre C,Bataille AR,Robert F&Giguere V. (https://doi.org/10.1038/onc.2017.151) tumors: morethanfatandblood. 2016 transcriptome andIL-8expressioninER-positivebreastcancer. overexpression mediatesendocrineresistancebyalteringtheER Li F, Shea M,Nardone A,DeAngelis C,Heiser LM 958–970. into enhancer-drivenlineage-specifictranscription. Carroll JS, Liu XS&Brown M.FoxA1translatesepigeneticsignatures pnas.0505575102) response. promoters revealsthatFOXA1definesadomainoftheestrogen From thecover:locationanalysisofestrogenreceptor{alpha}target doi.org/10.1016/j.cell.2005.05.008) requiring theforkheadproteinFoxA1. 113 E6600–E6609. (https://doi.org/10.1016/j.cell.2008.01.018) PNAS 2005 102 (https://doi.org/10.1073/pnas.1612835113) 11651–11656. Downloaded fromBioscientifica.com at10/03/202111:46:00PM Oncogene https://eje.bioscientifica.com Cell (https://doi.org/10.1073/ 2005 2017 184 :1 122 36 et al 5221–5230. Cell 33–43. . FOXA1 2008 α (https:// insolid 132 R15 PNAS via freeaccess