Dynamique - PDF document

Cours III (Fin) Dynamique de l함踀t踀rochromatine facultative Dynamics of facultative heterochromatin Cours IV Les troubles neurologiques liŽs au chromosome X AnnŽe 2017-2018 : 툀Le chromosome X - paradigme de la 枎溎tique et l햎pi枎netique CHAIRE₃PIG茀N茀TIQUE ET M茀MOIRE CELLULAIRE 19 暎vrier , 2018 E. Heard, February 19 th , 2018 Summary of Xi status in Somatic Cells of Mice, Humans and Marsupials ! E. Heard, February 12 th , 2018 "#$%&'â ©!$⤀*%⤀+,#+-!.+.&/$#$!0⤀1⤀.&⤀2!(3.(!450!.&&!6%(!5+⤀! 78&#+9⤀2!-⤀+⤀!⤀:.;#+⤀2! =$: �?!@05;5â ©0!ABC!;⤀(3/&.D5+!E.$! .6$⤀+(!.+2?!(3%$?!+5(!,500⤀&.()2!E#(3!@.0⤀+(854850#-#+!2#F⤀0⤀+D.&! .&&⤀&#,!⤀:@0⤀$$#5+G!H3#$!#$!,5+$#$â ©+(!E#(3!@0⤀1#5%$!$#+-&⤀8-⤀+⤀! .+.&/$⤀$!#+!;.0$%@#.&$! I.$&5E !.+2! J#-⤀5+ !KLMNO! P5)6)& !.+2! Q5

3+$(5+!KLLRO! S50+⤀,9⤀0 !⤀(!.&G!TUUN⤀?!6%(!,5+(0.0/!(5!(3⤀!2#F⤀0⤀+D.&! ;⤀(3/&.D5+!2⤀⠩,⠩2!6/!(E5! 2#F⤀0⤀+(;⤀(3525&5-#⤀$ !.(! (3⤀!E35&⤀8,305;5$5;⤀!&⤀1⤀&! P5)6)& !.+2!Q53+$(5+!KLLVO! =)+$ ! ⤀(!.&G!TUKU⤀G!H3#$!2#$,0⤀@.+,/!$%--⤀$($!(3.(!E3#&⤀!2#F⤀0⤀+D.&!ABC! ;⤀(3/&.D5+!54!;.0$%@#.&!7!,305;5$5;⤀$!,.+!5,,%0?!#(!#$!+5(! ,3.0.,⠩0#$D,!54!(3⤀!@05;5⠩0!0⤀-#5+$!54!(3⤀!;.W50#(/!54!78&#+9⤀2! -⤀+⤀$!.(!&⤀.$(!#+!5@5$$%;⤀?!.+2!(3⤀0⤀450⤀!;%$(!5,,%0!#+!5(3⤀0! 0⤀-#5+$!54!(3⤀!,305;5$5;⤀G! Marsupial Afrotherian Eutherian Xi CEN Xi CEN H3K9me2 ! ? ! H3K27me3 ! ! H4K20me1 ! H3K9me3 ! ! ! H3K27me1 ! ! H4K20me3 ! ! ! Pc? MacroH2A H2AK119Ub H3K27me3 H3K9me2 H4 K20me1 DNA methylation H3K36me3 H3Ac Ac H3K4me2, me3 H4Ac RNA Pol II Xist RNA Active X chromatin In

active X chromatin Barr body Late replicating MOUSE Pc? MacroH2A H2AK119Ub? H3K27me3 H3K9me3 H4K20me3 Rsx RNA Inactive X chromatin Barr body Late replicating MARSUPIAL Pc? H4 K20me1 DNA methylation H3K9me3 H4K20me3 HUMAN Diversity in heterochromatin marks: facultative heterochromatin is a means to an end: to compensate for X-linked gene dose Scaffold for repressor recruitment ? Nuclear compartmentalisation ? Chromatin changes ? How is Facultative Heterochromatin established? How does XIST work ? (X-Inactive-Speci�c-Transcript⤀ RNA-DNA binding ? E. Heard, February 12 th , 2018 E. Heard, February 12 th , 2018 Chromosome 3D organisation Transcriptional interference ? Post- transcriptional interference ? X&.)$ ! Y.3&⤀$â ©2⠀ ?!TUKV! !"#$%&"'⠀⤀*+,' Y.+-?!IX!.+2!X3.+-!SZ?!J5&⤀,%&.0! J),3.+#$;$!54!P5+-!B5

+,52#+-!=BC$G! J5& !X)&&G!TUKK![)@! &#xR000;KRO\V\\!! Long non-coding RNAs: from spurious transcription to functional entities E. Heard, February 12 th , 2018 !" #" $" %" &" '" ^!KN!UUU!8!KL!UUU! +( ?!$@&#,)2?! %+(0.+$&.()2 ?!+%,&⤀.0!(0.+$,0#@(! -' ./0% !#$! ⠩⤀(*+,- !450!7!#+.,D1.D5+!#+! 1/0 ' I_$?!(0.+$-⤀+⤀$!#+!;5%$⤀!⤀;60/5$?!`[!,⤀&&$⤀! ^!=BC!⤀:@0⤀$$⤀2!405;!.+2! ,5.($ !(3⤀!#+.,D1⤀!7!,305;5$5;⤀!#+! 1/0 ' +5(! %)#20 � ! ^!a550!$⤀*%⤀+,⤀!,5+$⤀01.D5+!6⤀(E⤀⤀+!;.;;.&$!8!⤀:,⤀@(!450!0⤀@⤀.($!C8b ' ^! 7#$⠀ !6#+2$!605.2&/!.,05$$!(3⤀!7!,305;5$5;⤀?!⤀:@&5#D+-!VA!$(0%,(%0⤀!450!#+#D.&!6#+2#+-! ^!`$D;.()2!cTUUU!;5&⤀,%&⤀$!54! 7#$⠀ !=BC!@⤀0!+%,&⤀%$! ^!X5+$⤀01⤀2! C !0⤀@⤀.($!⤀+$%0⤀! $#&)+,#+- !4%+,D5+! ^!J%&D@&⤀! 7#$⠀ !25;.#+$!0⤀*%#0⤀2!450! ,5.D+- !#+,&%2#+-!X!0⤀@⤀.($! ^! 7#$⠀ !=BC!0⤀@50â ©2!(5!0⤀,

0%#(!,305;.D+!4.,(50$! )- ! a5&/,5;6 !-05%@!@05â ©#+$?!;.,05STCd! ! ! !! ^! 7#$⠀ !,.+!5+&/!#+2%,⤀!$#&⤀+,#+-!2%0#+-!.+!⤀.0&/!2⤀1⤀&5@;⤀+(.&!D;⤀!E#+25E! e)+)!$#&)+,#+-! 3+=Ba !f!6#+2#+-! ggg!!!!!!!!!ggg!!!!!!!!!!!!!!!!!!!!!!ggg!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! ! ggg ! X305;5$5;⤀!,5.D+-! E. Heard, February 12 th , 2018 XIST RNA: A Multi-Tasking Molecule 0 1 2 3 4 5 6 7 8 9 Xist RNA coating begins in XX cells Transcriptional silencing begins Northerns , allele-speci� RT PCR, RNA FISH Days of in vitro differentiation (ES cells⤀ INITIATION Xist-dependent IRREVERSIBLE INACTIVATION Xist-independent Inducible Xist cDNA : Xist Tet Cellular Memory? Epigenetic Marks? Wutz et al Cell 2001, Nat. Genet. 2002 When does Xist trigger chromosome- wide silencing ? Xist RNA as a trigger for XCI E. Heard, February 12 th , 2018 Inducible Xist c

DNA : (Wutz and Jaenisch, 2001) Xist X Y TRE-Xist Tet X Y X Y Gene activity Survival Functional nullisomy for the X chromosome Cell death What are the Functional Domains of Xist RNA ? E. Heard, February 12 th , 2018 Wutz et al, Nature Genetics 2002 silencing association in cis E. Heard, February 12 th , 2018 What are the Functional Domains of Xist RNA ? e)+)!$#&)+,#+-! 0)-#5+! 3+=Ba!f!6#+2#+-! 0)-#5+ ! ggg!!!!!!!!!!!!!!!!ggg!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!ggg!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!ggg ! CCCC ! `! A! X! "! b! C! =)-#5+$!#+15&1⤀2!#+! 7#$(! =BC!,5.D+-!]! !"#$% ./!0 % E. Heard, February 12 th , 2018 What are the Functional Partners of Xist RNA ? 12,3 ",4("32(" 56*7+8*,- " 9,43*(4⤀ "85" :;)3 "./!" X3%!⤀(!.&?!X⤀&&!TUKh! E. Heard, February 12 th , 2018 e)+)!$#&)+,#+-! X305;5$5;)! ,5.D+-! X305;.D+! ;52#',.D5+! [#&⤀+(!+%,&⤀

.0! ,5;@.0(;⤀+(! #6⤀ " e)+)!$#&)+,#+-! 0)-#5+! CCCC ! `! A! X! "! b! C! !"#$% ./!0 % Xist RNA Functional Partners E. Heard, February 12 th , 2018 X3%!⤀(!.&?!X⤀&&!TUKh! e)+)!$#&)+,#+-! 0)-#5+! 3+=Ba!f!6#+2#+-! 0)-#5+ ! ggg!!!!!!!!!!!!!!!!ggg!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!ggg!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!ggg ! CCCC ! `! A! X! "! b! C! =)-#5+$!#+15&1⤀2!#+! 7#$(! =BC!,5.D+-!]! !"#$% ./!0 % ^! =*4�*9 "?@!#A!B" #$!0⤀*%#0⤀2!450! 7#$⠀ ! &5,.&#$.D5+ !.$!@0⤀1#5%$&/! �$35E+! ! ^! @9(* !A05$5@3#&.![@&#(!⤀+2$!35;5&5-!⤀!#+â ©0.,($!1#.!(3⤀!C80⤀@⤀.(! 25;.#+!54! 7#$⠀ !.+2!#$!0⤀*%#0⤀2!450!-⤀+⤀!$#&⤀+,#+-! ! ^! 13,9 " i!=BC!;⤀(3/&.D5+!;.,3#+⤀0/! ! ^! a5&/,5;6 !a=XK!4.,(50$! C7DEF" .GH9 " i!6%(! 2* !a=XT!4.,(50$! ! ^! =*4*9I ?!@.0D,#@.()$!#+! 7#$⠀ 8;⤀2#.()2!-⤀+⤀!$#&⤀+,#+-!.+2! 0⤀,0%#(;⤀+(!54!+5+8,.+5+#,.&! @5&/,5;6 !a=XK

!,5;@&⤀:!6%(!+5(! 7#$⠀ ! &5,.&#j.D5+! ! ^!P"=!i! J,K;* "$"4⠀7⠀9384"L"*67-⠀,4" 84D,*;),+8* ! X3%!⤀(!.&?!X⤀&&!TUKh! Xist RNA Functional Partners : a few examples E. Heard, February 12 th , 2018 :;)3 "./!"9,43*⠀4";⤀8-,+8*0" X3%!⤀(!.&?!X⤀&&!TUKh! J,S%-3!⤀(!.&?!B.(%0⤀!TUKh!! X3⤀+!⤀(!.&![,#⤀+,⤀!TUKR! J#+.W#-# !!⤀(!.&?![,#⤀+,⤀!TUKh! ! M(*(+7")74((*)"584" :;)3 "56*7+8*)0" J5#+205⠀ !⤀(!.&?!X⤀&&!=)@G!TUKh! J5+450⠀ !!⤀(!.&?!X⤀&&!=)@G!TUKh! E. Heard, February 12 th , 2018 Identi�cation of the Protein Partners of Xist RNA and the Factors that are implicated in Xist -mediated Silencing Holy Grail Or Pandora픀s box? Molecular investigation of Xist RNA function A new era of X-inactivation research! :;)3 "./!"9,43*⠀4";⤀8-,+8*0" X3%!⤀(!.&?!X⤀&&!TUKh! J,S%-3!⤀(!.&?!B.(%0⤀!TUKh!! X3⤀+!⤀(!.&![,#⤀+,⤀!TUKR! J#+.W#-#

!!⤀(!.&?![,#⤀+,⤀!TUKh! ! M(*(+7")74((*)"584" :;)3 "56*7+8*)0" J5#+205⠀ !⤀(!.&?!X⤀&&!=)@G!TUKh! J5+450⠀ !!⤀(!.&?!X⤀&&!=)@G!TUKh! [#;.5 !H⤀#:⤀#0.!2.!=5,3.! E. Heard, February 12 th , 2018 Xist non- coding RNA is a multi- tasking molecule essential for initiation of XCI ꔀ It induces gene silencing , spatial reorganisation of the X chromosome and chromatin changes ꔀ Mass- spec analysis of proteins bound to Xist RNA provide the �rst molecular handle for exploring its functions ꔀ The⃞rst regions Xist targets contain the⃞rst genes silenced Subsequent spreading due t漠윀 relay ! elements , or chromatin proteins , or spatial dynamics ? SUMMARY Xist RNA and the initiation of X inactivation E. Heard, February 12 th , 2018 Xist non- coding RNA is a multi- tasking molecule essential for

initiation of XCI ꔀ It induces gene silencing , spatial reorganisation of the X chromosome and chromatin changes ꔀ Mass- spec analysis of proteins bound to Xist RNA provide the �rst molecular handle for exploring its functions ꔀ The⃞rst regions Xist targets contain the⃞rst genes silenced Subsequent spreading due t漠윀 relay ! elements , or chromatin proteins , or spatial dynamics ? SUMMARY Xist RNA and the initiation of X inactivation E. Heard, February 12 th , 2018 Xist RNA exploits 3D genome architecture to spread across the X chromosome `+-0⤀#(j !⤀(!.&?!TUKV! =BC!C+D$⤀+$⤀!a%0#',.D5+!=Ca&#x-0.2;]! J.@@#+-!54! 7#$⠀ ! &+,=BC !! #+â ©0.,D5+$!E#(3!,305;.D+! b05;! e)+20)& !.+2!S).02?!TUK尀! P#⤀6⤀0;.+8C#2⤀+!⤀(!.&?!TUUL! X5;@0⤀3⤀+$#1⤀!;.@@#+-!54!&5+-80.+-⤀! #+â ©0.,D5+$!0⤀1⤀.&$!45&2#+-

!@0#+,#@&⤀$! 54!(3⤀! 3%;.+! -)+5;) ! E. Heard, February 12 th , 2018 b#0$(!0⤀-#5+$!54!(3⤀!7!,305;5$5;⤀!(3.(! .$$5,#.()!E#(3! 7#$⠀ !=BC!,5+(.#+!$5;⤀!54!(3⤀! '0$(!-⤀+⤀$!$#&⤀+,⤀2!2%0#+-!7Xk ! N4,*)74;9+8*" K,72;*(4G " "?./!" C8-OO B" :;)3 "./!"#O@= "P" M⠀*⠀"&/!"#O@=" :;)3 "./!" &/!" Xist RNA forms a silent nuclear compartment and triggers spatial reorganisation of the Xi during XCI Xist RNA X3.%;⤀#& !⤀(!.&?! e)+)$ ! A)1 G!TUUR! 7#$⠀ !=BC! ./!"C8-"OO"O# P ./!"#O@=" 78 &#+9⤀2 ! -)+⤀ ! K .0/ ! (0.+$,0#@⠀ ! =BC!a5&!kk! Xa k+$#2⤀! _%⠩0 ! )2-) ! Genes undergoing inactivation are internalised into the Xist RNA compartment, expressed genes (escapees) remain external CTCF-driven looping out? Transcription-driven sequestration? Xist A-repeat proteins Spen , WTAP) facilitate interbalisation ? Chaumeil et al, Genes Dev. 2006; Chow et al,

Cell 2010 E. Heard, February 12 th , 2018 3/&4&⤀+#25 !/"&2 '&%'#67'899: ' 128-⠀ " D(*8K( " K,9 " O*34,7248K8)8K,- " 78*3,73" K,9⤀ " N898-8D;7,--G " ,))87;,+*D " Q8K,;*) " ; ' 1⤀= ' �?.'16@0%&⤀ ' 1⤀A ' 1⤀8 ' 1⤀B ' 1⤀C ' 1⤀D ' 1⤀= ' Investigating the molecular architecture of the active and inactive X chromosomes using Hi-C Q56!A)99)0! %8K9,43K(*3⤀ ! E#(3!2#$D+,D1⤀! @.l⤀0+$!54! )@#-)+5;#, !4⤀.(%0⤀$! m.0#.6&⤀!6⤀(E⤀⤀+!D$$%⤀$?!! X⤀&&8(/@⤀!$@⤀,#', ! N!&⤀ !KUU968KJ6! $,.&⤀ �! k+1.0#.+(! .&;5$⠀ �! 6⤀(E⤀⤀+ !D$$%)$! B50.!⤀(!.&?!TUKT! X5+$)01⤀2 !;.+n;5%$⤀⤀! A#:5+!⤀(!.&?!TUKT! E. Heard, February 12 th , 2018 mRNAseq analysis of 8 independent NPC clones (4 XX and 4 XY⤀ Bioninformatic and statistical analysis Autosomal genes showing random monoallelic expression in NPCs In vitro and in viv

o validation in non-polymorphic (inbred) cells ꔀ Mono vs biallelic expression: identi�cation and in vivo validation of RME autosomal genes ꔀ X-inactivation status based on RNA- Seq in four independent female NPC clones: F1 Hybrid ES cell line (129xCast� = 1 SNP /~100bp) Neural Progenitor cells Differentiation X-chromosome inactivation (XCI) NPC clone isolation RNA Seq Ð allele-speci�c analysis of gene expression Plate low density Generation of clonal cell lines Allele-speci�c RNA seq and Hi-C in clonal F1 129/Cast ESCs and NPCs 129 Cast Chr X Xa 129 Xa Cast Differentiation Neural Progenitor cells (NPC) Random X chromosome inactivation (XCI) Isolate NPC clones 100% cells with 129 or cast Xi Subcloning Xa 129 Xi Cast Xi 129 Xa Cast Gendrel et al, Dev. Cell 2014) Dekker Lab: Ye Zhan, Bryan Lajoie Heard Lab: Mikael Attia ,

Luca Giorgetti E. Heard, February 12 th , 2018 K./!)⠀R ",*,-G);)"85"S";*Q(9(*Q(*3" /C%"7-8*()"?T"::",*Q"T":UB" $;8*;*584K,+7 ",*Q" )3,+)+7,-",*,-G);)" !638⤀8K,-"D⠀*⠀⤀"⤀28V;*D"4,*Q8K" K8*8,--(-;7 "(W94());8*";*"/C%)" &'%⠀"$)*% ,*Q" "'%⠀"(*% X,-;Q,+8*" ;*"*8*A98-GK8492;7"?;*H4⠀QB" 7(--⤀"" ^!J5+5! 1$ ! 6#.&&⤀&#, !⤀:@0⤀$$#5+]!#2⤀+D',.D5+!.+2! /2'E/E*' 1..D5+!54!=J`!.%(5$5;.&!-⤀+⤀$! ^!78#+.,D1.D5+!$(.(%$!6.$⤀2!5+!=BC8 [)* !#+!45%0!#+2⤀@⤀+2⤀+(!4⤀;.&⤀!BaX!,&5+⤀$]! F1 Hybrid ES cell line (129xCast� = 1 SNP /~100bp) /(64,-"C48D(*;384"7⠀--)" A#F⤀0⤀+D.D5+ !! :A7248K8)8K⠀";*,7+X,+8*"?:%OB" /C%"7-8*(";)8-,+8*"" ./!" @(R "L",--⠀-⠀A⤀9⠀7;Y7",*,-G⤀;⤀"85"D⠀*⠀"⠀W94⠀⤀⤀;8*" a&.()!&5E!2⤀+$#(/! e⤀+⤀0.D5+!54!,&5+.&!,⤀&&!&#+⤀$! 129 Cast Chr X Xa 129 Xa Cast Differentiation Neural Progenitor cells (NPC) Ran

dom X chromosome inactivation (XCI) Isolate NPC clones 100% cells with 129 or cast Xi Subcloning Xa 129 Xi Cast Xi 129 Xa Cast e)+20)& !⤀(!.&?!A⤀1G!X⤀&&!TUK尀尀! =BC8 $)* ! e)+20)& !⤀(!.&?!TUK尀尀! S#X8$⤀* ! ,5&&.6 G!Q56!A)99⤀0⤀! CHCX8 $)* ! ,5&&.6 G!SG!X3.+-�! ./!" @(R " Allele-speci�c analysis in clonal, polymorphic embryonic stem cells & neural progenitor cells E. Heard, February 12 th , 2018 ꔀ Global silencing of one X chromosome but escape from XCI in multiple regions of the X ꔀClusters of facultative escapees in NPCs ( Gendrel et al, 2014) Ð vary between different clones Also seen in Trophoblast Giant Cells at E8.0 ( in vivo ) (Catherine Corbel⤀ Unique Chromosome Organisation of the inactive X E. Heard, February 12 th , 2018 Nora et al, Nature 2012 Giorgetti et al, 2016 3@1#' F/*)G&H ' bJk?!".$⤀&⤀!

! ! " Z"�*;R6⠀"[&" 84D,*;),+8* "85"32⠀":;0"D-8H,--G"4,*Q8K";*3⠀4,7+8*⤀F"-8⤀⤀"85"N!&⤀F"9,4++8*;*D" ;*38"3V8"-,4D⠀" K(D,Q8K,;*⤀ "⤀⠀9,4,3⠀Q"HG"32⠀"78*⤀⠀4X⠀Q"&:\T" K,748⤀,3(--;3⠀ "4(D;8*" !!!A7o尀!2⤀&⤀D5+!&⤀.2$!(5! ;⤀-.25;.#+ !2#$0%@D5+! !i!05&⤀!#+!k+$%&.D5+p!H⤀(3⤀0#+-p! " ! % ! ' " Does CTCF act as a border? Does CTCF act as a border? =_P`!54! ;⤀-.25;.#+ !@.0DD5+#+-p! J5%$⤀!I5$d! 5+-5#+3 ! X.+,⤀0!]!7#!#$!⤀052⤀2!i!E3.(!.65%(!$(0%,(%0⤀!i! S%;.+!,.+,⤀0!(55!,5;@&⤀:!.&&⤀&⤀8$@⤀,#',⤀!qr!;5%$⤀!;52⤀&! H⤀(J/, ! e#50-)s ?! P.5#⤀ ?!X.0â ©0?! Cs. !⤀(!.&G!B.(%0⤀?!TUKR! O)"⠀)7,9("548K":%O",*"877,);8*,-"⠀9;D⠀*(+7"],77;Q(*3^"84"Q8()";3"2,X⠀","5⠀K,-(A )9(7;Y7",QX,*3,D(" e#50-)s !P!⤀(!.&G!t[(0%,(%0.&!50-.+#j.D5+!54!(3⤀!#+.,D1⤀!7!,305;5$5;⤀!#+!(3⤀!;5%$⤀uG! I#%@⤀& !hVh]hNh8L! &#xTUKR; Two supe

r-domains and global absence of topological domains Facultative escape correlates with local 3D-organisation (TADs⤀ And is i滟uenced by the unusual DXZ4 regi潮준 Unique Chromosome Organisation of the inactive X E. Heard, February 12 th , 2018 " Z"�*;R6⠀"[&" 84D,*;),+8* "85"32⠀":;0"D-8H,--G"4,*Q8K";*3⠀4,7+8*⤀F"-8⤀⤀"85"N!&⤀F"9,4++8*;*D" ;*38"3V8"-,4D⠀" K(D,Q8K,;*⤀ "⤀⠀9,4,3⠀Q"HG"32⠀"78*⤀⠀4X⠀Q"&:\T" K,748⤀,3(--;3⠀ "4(D;8*" !!!A7o尀!2⤀&⤀D5+!&⤀.2$!(5! ;⤀-.25;.#+ !2#$0%@D5+! !i!05&⤀!#+!k+$%&.D5+p!H⤀(3⤀0#+-p! " ! % ! ' " Does CTCF act as a border? Does CTCF act as a border? =_P`!54! ;⤀-.25;.#+ !@.0DD5+#+-p! J5%$⤀!I5$d! 5+-5#+3 ! X.+,⤀0!]!7#!#$!⤀052⤀2!i!E3.(!.65%(!$(0%,(%0⤀!i! S%;.+!,.+,⤀0!(55!,5;@&⤀:!.&&⤀&⤀8$@⤀,#',⤀!qr!;5%$⤀!;52⤀&! H⤀(J/, ! e#50-)s ?! P.5#⤀ ?!X.0â ©0?! Cs. !⤀(!.&G!B.(%0⤀?!TUKR

! O)"⠀)7,9("548K":%O",*"877,);8*,-"⠀9;D⠀*(+7"],77;Q(*3^"84"Q8()";3"2,X⠀","5⠀K,-(A )9(7;Y7",QX,*3,D(" b05;!=5,3.!.+2!S).02!TUKN! Facultative escape correlates with local 3D-organisation of the chromatin �bre and is i滟uenced by the DXZ4 macrosatellite ? Unique Chromosome Organisation of the inactive X E. Heard, February 12 th , 2018 E. Heard, February 12 th , 2018 SVC,! SVI尀;⤀T! S\C,! ./!" C8-"OO" I+5E+ !! 7#8 .$$5,#.()2 !! @05â ©#+$ ] ! SVIVR! ;)V! SVI尀;⤀V! !7+X⠀"D⠀*⠀" TF C7 J.,05STC! STCIKKRf6! SVITN;⤀V! SVIL;⤀T! S\! ITU;)K ! ABC!! ;⤀(3/&.D5+! _,;*3⠀*,*7⠀"" ! =)1#⤀E⤀2!#+]! e)+20)& !.+2!S).02?! !227'J&E7'K&E7'L/*6 G!TUK尀! =5,3.!.+2!S).02?! IMNL ?!TUKN! OJP8Q'OJPA'RP4STUQ'' OJPA56/V&''R JW4$ U' +#1)*�8!Q'!XJ.Q'MNP�KA' PKY3Q'L!�K;' ' ? TF ? ? SVITN ;)V! SVIL;⤀T! ')7,9("548K":%O"" ? (D " +,)"-./0% 1$2 B" ./

!" C8-"OO" k+$%&.(50!⤀&⤀;⤀+($! .PZ5⤀&0/0%#2%'X[0尀' Z20@6#%*⤀'&6&+&2%0尀' M$&1/#6/]&"'1⤀*+#^2'0%#%&尀' a.(0.( !⤀(!.&?! OI!M !TUUL! X506⤀&!⤀(!.&?! K&E&6*$+&2% ?!TUKV! e)+20)& !⤀(!.&?! K&E7'P&66 ?!TUK\! X3%!⤀(!.&?!X⤀&&!TUKh! J,S%-3!⤀(!.&?!B.(%0⤀!TUKh! J#+.W#-# !⤀(!.&?![,#⤀+,⤀!TUKh! ! :;)3 "./!" SVC,! S\C,! ./!" C8-"OO" :;⤀3"./!"78,+*D" O*;+,+8*"85"D⠀*(");-(*7;*D" TF SVI尀;⤀T! SVIVR! ;)V! SVI尀;⤀V! ? LBR, SAF-A줠 SPEN RBM15 &;`(4(*3"D(*â ©",4(");-(*7(Q",3" X(4G"Q;`(4(*3"+K()"Q64;*D":%O" A)8K("D(*()");-(*7(Q";KK(Q;,3(-G" _/⠀CQ'P/1AQ'J2⠀A8 �! A832(4)");-(*7(Q"8*-G",a(4")(X(4,-"7(--" Q;X;);8*)" )- ! �@`&A �! @8K⠀"D(*()"()7,9(":%O" 78*⤀+36+X(-G"b",638*8K86⤀-G" )- ! a#)/"A1 ?!P#!.+2!X.00⤀&?! OI!M' �TUUM! " " " 'D " 34/56 "⠀⤀7,9⠀⤀":%O";*"*⠀64,-"⤀3⠀K"7⠀--⤀";*"

32⠀"@c\" SVITN ;)V! SVIL;⤀T! .(,7+X,+8*"548K"32⠀":;" ./!" C8-"OO" ? ? SVI尀;⤀! SVnS\C,! 3/2&#G&50$&1/b1'X[0尀' M$&1/#6/]&"'1⤀*+#^2'0%#%&尀' TF ? STCI! KKRf6! @8K⠀"D(*()"()7,9(":%O" 78*⤀+36+X(-G"b",638*8K86⤀-G" )- ! c%S ?! a#)/"A1 ?!P#!.+2!X.00⤀&?! OI!M' �TUUM! " @8K⠀"D(*()"()7,9(";*","-;*(,D("84" +)⤀6(A)9(7;Y7"5,⤀2;8*" )- ! !%)S ?! a.(0.( !⤀(!.&?! OI!M �!TUUL!! ! #+!HeX$!8!X506⤀&!⤀(!.&?! K&E&6*$+&2% ?!TUKV!! k+!BaX$!8! e)+20)& !⤀(!.&?! K&E7'P&66 ?!TUK\! e#50-)s !⤀(!.&?! I#%@⤀& ?!TUKR! ! " " " ')7,9(⠀⤀ ",4(" 8a(* " ;*X8-X⠀Q ";*" 7248K,+*A,⤀⤀87;,3(Q "" 56*7+8*⤀ " (D "d,4;Qe7F" �3W "f"=;⤀38*⠀" Q(K⠀32G-,)(⤀ " !34W "f" 7248K,+* " 4(K8Q(--(4 " ')7,9(⠀⤀ ",4(" 8a(* " ;*X8-X⠀Q ";*" 7248K,+*A,⤀⤀87;,3(Q "" 56*7+8*⤀ " (D "d,4;Qe7F" �3W "f"=;⤀38*⠀" Q(K⠀32G-,)(⤀ " !34W "f" 7248K,+* " 4(K8Q(

--(4 " " X-inactivation events: gene silencing and escape J5%$⤀!7! 'W94⠀));8*"85","Q86H-("Q8)("85")8K⠀"D(*()";)" ;K9843,*3";*"26K,*"5⠀K,-()" ?:g"0"N64*(4 )")G*Q48K⠀B" Genes that can escape from X inactivation 'W94⠀));8*"85","Q86H-("Q8)(";*"5⠀K,-()";)" *83"⠀⤩⠀*+,-" ;*" K;7( "?*8":g" 92(*83G9( B" 7'84## % $94: %9,(4%,'%"',/;(4%! % S%;.+!7! X.00⤀&!.+2!Y#&&.02?!TUUh! ^! @8K⠀"D(*()"K,G" 2,X⠀ "38"⠀⤀7,9⠀F"832⠀4⤀"K,G"⠀⤀7,9⠀"Q6⠀"38"h-⠀,iGj"84";*⠀k7;⠀*3"⤀;-⠀*7;*D" ^! &;`(4(*3"+)⤀6⠩P-;*(,D()";*"32("K86⤀(")28V"Q;`(4(*3"Q(D4(()"85"()7,9⠀ !X506⤀&!⤀(!.&?!TUKV⤀!! ^! @8K⠀"D(*()")28V"-;*(,D(A)9(7;Y7"()7,9("548K":";*,7+X,+8*" )- ! !%)S ?! a.(0.( !⤀(!.&?!TUUL⤀! ^! _(72,*;⤀K⤀"85"⠀⤀7,9⠀"6*7-⠀,4l!"48-⠀"584"7248K,+*"⤀3467364⠀"L"N!&⤀F"-889;*Dl" E. Heard, February 12 th , 2018 ! A few escapees have Y-linked h

omologs, most do not ! Escape may be accidental (epigenetic instability) or purposeful (requirement of a double dosage in XX⤀ ! Escape may underlie some sex chromosome dosage effects on several sex-biased metabolic, immune and neurological phenotypes (MORE NEXT WEEK) E. Heard, February 19 th , 2018 X-inactivation: gene silencing and escape Variability across Human Tissues Genes in the pseudoautosomal region show higher expression in XY males than in XX females� = lower activity of PAR region on Xi? Multiple regions show female bias: ie escape from XCI Ð this is variable between tissues and individuals Sex bias pattern of nine genes not classi�ed as full escape genes that follow a similar proÞle to established escape genes E. Heard, February 19 th , 2018 X-inactivation: gene silencing and escape Variability across Human Tissues E. Heard, February

19 th , 2018 Variable escape from XCI in different tissues: How does this relate to epigenetic status of the Xi? Are the different epigenomic landscapes (H3K27me3/Pc vs H3K9me3/HP1) linked to the cell type speci�c differences? Or is the difference gene-speci�c or gene cluster-speci�c? Is it related to looping/TAD formation on the Xi? Carrel and Willard (2005) Nature 434, 400-404 Variable escape from X inactivation leads to even greater female cellular mosiacism In humans, up to 25% of X-linked genes can escape from X inactivation ie are biallelic )! 10% of these escape constitutively 15% of these genes show variability between individuals Ð and tissue speci�city E. Heard, February 12 th , 2018 Huntington Willard Ð 2005: 툀Genetically speaking, if you've met one man, you've met them all. We are, I hate to say it, predict

able. You can't say that about women. Men and women are farther apart than we ever knew. It's not Mars or Venus. It's Mars or Venus, Pluto, Jupiter and who knows what other planets⻓ Everyone is unique: females even more so준 Consequences on physiology, behaviour , disease? "0.#+!$⤀,D5+! v!k;.-⤀![(0⤀.;!w!k;.-#+-!x5E! ,/(5;⤀⠩0 ! ! =5)$ �?*@,$*A =5)$ �BCD " No two females, not even twins, are identical when it comes to X-linked traits XCI mosaicism creates diversity between and within individuals. Within an individual, inhomogeneities in the XCI mosaic in any particular tissue re�ect the interplay of : (1) the ratio of founder cells to adult cells; (2) the timing and extent of cell migration during development; (3) alleles that may be counter-selected in speci�c cell types "0.#+!$⤀,D5+! ! =5)$ �?*@,$*A =5)$ �BCD " No

two females, not even twins, are identical when it comes to X-linked traits In the Central Nervous System: Cell-type differences in XCI mosaicism in the cerebral cortex; mosaicism in CNS Vasculature A diversity-generating mechanism such as XCI, which operates on all cells within the CNS and creates diversity on a spatial scale that encompasses the scale of local circuits, has the potential to add functionally relevant capabilities . Because XCI affects 50% of the individuals in every species of eutherian mammal and because it epigenetically silences one allele among 4% of genes, it may represent one of the more signi�cant mechanisms by which individual differences in CNS function are generated. HE5!6#5,3⤀;#,.&&/!2#$D+,(!(/@⤀$!54!+⤀%05+$! qr!(3⤀!⤀+$⤀;6&⤀y$!2/+.;#,!0.+-⤀!#$! ⤀&/!(5! 6⤀!⤀:@.+2⤀2!.&5+-!(3⤀!$D;%&%$!.:#$G!! E. Heard, Februar

y 19 th , 2018 Females are Mosaics However , X-chromosome activity can be skewed for different reasons b05;! e)+20)& !.+2!S).02?!A⤀1⤀&5@;⤀+(!TUKK! Different mutations or genetic variants can i滟uence the degree of mosaicism in an individual Within individuals, different organs can have different degrees of mosaicism if selection for/against cells with a particular allele expressed can occur With age the inactive X chromosome can be lost in some cells준 Implications of X inactivation for X-linked Diseases E. Heard, February 19 th , 2018 Severe phenotypes or lethality in males Variable and sometimes no phenotypes in females Eg Fragile X syndrome, Haemophilia , muscular dystrophy , Incontinentia pigmenti !H⠀44,*3":A-;*i(Q"D⠀*⠀"Q8⤀,D⠀"7,*"7,6⤀⠀"Q;⤀⠀,⤀⠀" X-linked mental retardation (XLMR) ! X-linked intellectual disabi

lity(XLID) 撎�ience intellectuelle ' !H⠀44,*3":A-;*i(Q"D⠀*⠀"Q8⤀,D⠀"7,*"7,6⤀⠀"Q;⤀⠀,⤀⠀" X-linked mental retardation (XLMR) ! X-linked intellectual disability(XLID) 撎�ience intellectuelle ' ! Mutation or silencing upon methylation of triplet expansions of FMR1 gene at Xq27 lead to dendritic spine abnormalities, impaired synaptic plasticity and mental retardation. ! FMR1 knockout mice show subtle behavioral and visual-spatial di曞culties ! FMRP loss leads to dysregulated protein translation at synapses ! Pathophysiological basis of cognitive i滟exibility in FXS? Invariant tuning of single-cell responses and inadequate discharge coordination within neural ensembles (Talbot et al, Neuron 2018) Fragile X Syndrome (FXS): ! _0+#(3#+⤀!(0.+$,.06.;/&.$⤀!2⤀',#⤀+,/!_HX&#x-0.2;! a35$@35-&/,⤀0.()!9#+.$⤀!2⤀',#⤀+,/!aeIK&#x-0.2;!

[(5,,5!25$![.+(5$!IkCCKTUT&#x-0.2;! 7PJ=8,&⤀z!&#@n@.&.()!aSbM&#x-0.2;! `@#&⤀@$/n;.,05,⤀@3.&/![ZBK&#x-0.2;! K ! V ! T ! h ! T ! M ! K ! K ! K ! T ! T ! R ! T ! N ! T ! ! T ! V ! 22.3 22.2 22.1 21.3 21.2 21.1 11.4 11.3 11.1 21.1 21.2 21.3 22.1 22.2 22.3 X5{+8P5E0/!=[IT&#x-0.2;! C.0$95-!beAZ&#x-0.2;! H⤀&⤀,.+(3%$83/@5$@.2#.$!JkAK&#x-0.2;! a/0%1.()!2⤀3/205-⤀+.$⤀!2⤀',#⤀+,/!aASCK&#x-0.2;! e&/,⤀05&!9#+.$⤀!2⤀',#⤀+,/!eIA&#x-0.2;! A%,3⤀++⤀!;%$,%&.0!2/$(05@3/!AJA&#x-0.2;! J5+5.;#+⤀!5:#2.$⤀8C!2⤀',#⤀+,/!JC_C&#x-0.2;! B500#)!BA&#x-100;a! a⤀&#j.)%$8J)0j6.,3⤀0!aPa&#x-0.2;! J5308H0.+⤀6W.)0-!AAa?!HkJJMC&#x-0.2;! 78&#+9⤀2!&#$$⤀+,⤀@3.&/!AX&#x-0.2;7! P5E⤀!_X=PK&#x-0.2;! [#;@$5+8e5&.6#8"⤀3;⤀&!eaXV&#x-0.2;! P⤀$,38B/3.+!Sa=H&#x-0.2;! b0.-#&⤀!7C!bJ=K&#x-0.2;! J%,5@5&/$.,,3.0#25$#$!kkC!kA[&#x-0.2;! J/5(%6%&.0!;/5@.(3/!JHJK&#x-0.2;! C20⤀

+5&⤀%952/$(05@3/!C"XAK&#x-0.2;! 78&#+9⤀2!3/205,⤀@3.&/8JC[C!$@⤀,(0%;!PKXC&#x-0.2;J! .(m F"CC_A:"?_'%CnBo" k+,5+D+⤀+D.!@#-;⤀+D!B`J_?!kI"Ie&#x-0.2;! A/$9⤀0.(5$#$!,5+-⤀+#(.!AIXK&#x-0.2;! 7PJ=8S/@5(5+#,!b.,#⤀$! ! 8(3.&.$$⤀;#.!;⤀+(.&!0⤀(.02.D5+?!! X.0@⤀+⠩08Y.j#0#?!S5&;⤀$8e.+-?!X3%2&⤀/!P5E0/?!! Q%6⤀0-8J.0$#2#p&#x-0.2;?![;#(38b#+⤀;.+8J/⤀0$p&#x-0.2;! 7Ba?!7ST&#x-0.2;! 7PJ=85@D,!.(05@3/!CeH=T&#x-0.2;! a.0D+-(5+?!Y⤀$(?!a05%2?!7PCe!C&#x-0.2;=7! !! "|0W⤀$5+8b50$$;.+8P⤀3;.++!aSbR&#x-0.2;! _0.&84.,#.&82#-#(.&!k!_bAK&#x-0.2;! [@⤀0;#+⤀!$/+(3.$⤀!2⤀',#⤀+,/![J[&#x-0.2;! 7PJ=n-05E(3!350;5+⤀!2⤀',#⤀+,/![_7V&#x-0.2;! a⤀0#1⤀+(0#,%&.0!+52%&.0!3⤀⠩05(5@#.?!_(5@.&.(52#-#(.&!K?!!!! !!!_(5@.&.(52#-#(.&!T?!!J)&+#,98B⤀⤀2&⤀$! (FLN1, FLNA) J)+9⤀$!2#$⤀.$⤀!CHaNC&#x-0.2;! 7PJ=8#+4.+D&⤀!$⤀#j%0⤀$?!=)l! ⤀![HIL&#x-0.2;! B.+,⤀8S50.+!BS[

&#x-0.2;! 7PJ=8,⤀0⤀6⤀&&.0!2/$-⤀+⤀$#$!_aSB8K&#x-0.2;! M4((*V88Q"M(*(+7"%(*3(4F"69Q,3(Q"d6-G"nppq" 7J=`!=)+#+!0⤀,⤀@(50O!CHaRCaT⤀! C%D$;!BP&#x-100;eB\! _bXA?!P⤀+j!;#,05@3(3.&;#.!"X_&#x-0.2;=! 7PJ=8,350⤀5.(3⤀(5$#$!SCAST&#x-0.2;! Allan-Herndon (MCT8, SLC16A2) X0⤀.D+⤀!(0.+$@50⠩0!2⤀',#⤀+,/![PXRCM&#x-0.2;! A.+5+!,.02#5;/5@.(3/!PCJaT&#x-0.2;! C0($?!a=aa!$/+(3⤀(.$⤀!$%@⤀0.,D1#(/!a=a[K&#x-0.2;! 78&#+9⤀2!X50+⤀&#.!2⤀!P.+-⤀![JXKPK?![JXKC&#x-0.2;! _@#(j8I.1⤀--#.!be?!P%W.+!J`AKT?!S_aC&#x-0.2;! JkAC[!SXX[&#x-0.2;! H%0+⤀0?!7PJ=83/205,⤀@3.&/8! 6.$.&!-.+-&#.!,.&,#',.D5+!! 7PJ=83/@5-5+.2#$;8(0⤀;50!XfP尀"尀! 7PJ=8+.#&!2/$(05@3/8$⤀#j%0⤀$!f"`TC&#x-0.2;! XLMR-macrocephaly-large ears (BRWD3) 7PJ=8;.,05,⤀@3.&/8J.04.+5#2!3.6#(%$!oASSXL&#x-0.2;! X30#$D.+$5+?!C+-⤀&;.+8 ⤀!![PXLCR&#x-0.2;! benP%W.+!@3⤀+5(/@⤀!fabV"&#x-0.2;! e0.3.;!,5&565;.!ke"aK&#x

-0.2;! C%D$;!=aPKU&#x-0.2;! 7PJ=8$350(!$(.(%0⤀8;%$,&⤀!E.$D+-!B7bh&#x-0.2;! Cantagrel spastic paraplegia (KIAA2022) 78&#+9⤀2!mCXH`=P83/205,⤀@3.&%$!bCBX"&#x-0.2;! J#(5,35+20#.&!⤀+,⤀@3.&5@.(3/!BAfbCK&#x-0.2;! X3#/5+56%!7PJ=!e=kCV&#x-0.2;! =)+@⤀++#+- ?![%(3⤀0&.+28 S..+ ?! X⤀0⤀605@.&.(5,.02#., !S.;⤀&⤀?! e5&.6# 8k(58S.&&?! a50â ©5%$ ! }"aꄀ8K! 11.23 11.22 11.21 7PJ=83/@⤀0⤀9@&⤀:#.8$⤀#j%0⤀$!C=Se`bL&#x-0.2;! e5&(j!a_=XB&#x-0.2;! H%0+⤀0!;.,05,⤀@3.&/!SfY`K&#x-0.2;! !a섀K[T! `@#&⤀@$/8;⤀+(.&!0⤀(.02.D5+!&#;#â ©2!(5!4⤀;.&⤀$!aXASKL&#x-0.2;! k,3(3/5$#$!45&&#,%&.0#$?!.(0#,3#.?!@35(5@356#.!J"Ha[T&#x-0.2;! !H⠀44,*3":A-;*i(Q"D⠀*⠀"Q8⤀,D⠀"7,*"7,6⤀⠀"Q;⤀⠀,⤀⠀" X-linked mental retardation (XLMR) ! X-linked intellectual disability(XLID) 撎�ience intellectuelle ' Implications of X inactivation for X-linked Diseases E. Heard,

February 19 th , 2018 Lethality in males Severe and variable phenotypes in females Rett Syndrome (MECP2) Ð affects 1/10 000 girls⃐  severe form of autism Affected daughter !H⠀44,*3":A-;*i(Q"D⠀*⠀"Q8⤀,D⠀"7,*"7,6⤀⠀"Q;⤀⠀,⤀⠀" Rett Syndrome ! ! Rett syndrome (RTT) : progressive neurodevelopmental disorder (Andreas Rett , 1966) ! One of the most common causes of mental retardation in females (incidence 1 in ~10,000) ! Patients with classic RTT appear to develop normally until 6Ð18 months of age, then gradually lose speech and purposeful hand use, and develop microcephaly, seizures, autism, ataxia, intermittent hyperventilation and stereotypic hand movements. ! After initial regression, the condition stabilizes and patients usually survive into adulthood. ! RTT occurs almost exclusively in females ! Mecp2 was identi�ed in 1999 as th

e gene responsible for Rett픀s syndrome. Mecp2 re-expression can reverse neurological defects observed in Rett Syndrome mouse model ! E. Heard, February 19 th , 2018 Functions of Mecp2 protein and role(s) in Rett Syndrome? E. Heard, February 19 th , 2018 _0+#(3#+⤀!(0.+$,.06.;/&.$⤀!2⤀',#⤀+,/!_HX&#x-0.2;! a35$@35-&/,⤀0.()!9#+.$⤀!2⤀',#⤀+,/!aeIK&#x-0.2;! [(5,,5!25$![.+(5$!IkCCKTUT&#x-0.2;! 7PJ=8,&⤀z!&#@n@.&.()!aSbM&#x-0.2;! `@#&⤀@$/n;.,05,⤀@3.&/![ZBK&#x-0.2;! K ! V ! T ! h ! T ! M ! K ! K ! K ! T ! T ! R ! T ! N ! T ! ! T ! V ! 22.3 22.2 22.1 21.3 21.2 21.1 11.4 11.3 11.1 21.1 21.2 21.3 22.1 22.2 22.3 X5{+8P5E0/!=[IT&#x-0.2;! C.0$95-!beAZ&#x-0.2;! H⤀&⤀,.+(3%$83/@5$@.2#.$!JkAK&#x-0.2;! a/0%1.()!2⤀3/205-⤀+.$⤀!2⤀',#⤀+,/!aASCK&#x-0.2;! e&/,⤀05&!9#+.$⤀!2⤀',#⤀+,/!eIA&#x-0.2;! A%,3⤀++⤀!;%$,%&.0!2/$(05@3/!AJA&#x-0.2;! J

5+5.;#+⤀!5:#2.$⤀8C!2⤀',#⤀+,/!JC_C&#x-0.2;! B500#)!BA&#x-100;a! a⤀&#j.)%$8J)0j6.,3⤀0!aPa&#x-0.2;! J5308H0.+⤀6W.)0-!AAa?!HkJJMC&#x-0.2;! 78&#+9⤀2!&#$$⤀+,⤀@3.&/!AX&#x-0.2;7! P5E⤀!_X=PK&#x-0.2;! [#;@$5+8e5&.6#8"⤀3;⤀&!eaXV&#x-0.2;! P⤀$,38B/3.+!Sa=H&#x-0.2;! b0.-#&⤀!7C!bJ=K&#x-0.2;! J%,5@5&/$.,,3.0#25$#$!kkC!kA[&#x-0.2;! J/5(%6%&.0!;/5@.(3/!JHJK&#x-0.2;! C20⤀+5&⤀%952/$(05@3/!C"XAK&#x-0.2;! 78&#+9⤀2!3/205,⤀@3.&/8JC[C!$@⤀,(0%;!PKXC&#x-0.2;J! .(m F"CC_A:"?_'%CnBo" k+,5+D+⤀+D.!@#-;⤀+D!B`J_?!kI"Ie&#x-0.2;! A/$9⤀0.(5$#$!,5+-⤀+#(.!AIXK&#x-0.2;! 7PJ=8S/@5(5+#,!b.,#⤀$! ! 8(3.&.$$⤀;#.!;⤀+(.&!0⤀(.02.D5+?!! X.0@⤀+⠩08Y.j#0#?!S5&;⤀$8e.+-?!X3%2&⤀/!P5E0/?!! Q%6⤀0-8J.0$#2#p&#x-0.2;?![;#(38b#+⤀;.+8J/⤀0$p&#x-0.2;! 7Ba?!7ST&#x-0.2;! 7PJ=85@D,!.(05@3/!CeH=T&#x-0.2;! a.0D+-(5+?!Y⤀$(?!a05%2?!7PCe!C&#x-0.2;=7! !! "|0W⤀$5+8b50$$;.+8P⤀3;.++!aSb

R&#x-0.2;! _0.&84.,#.&82#-#(.&!k!_bAK&#x-0.2;! [@⤀0;#+⤀!$/+(3.$⤀!2⤀',#⤀+,/![J[&#x-0.2;! 7PJ=n-05E(3!350;5+⤀!2⤀',#⤀+,/![_7V&#x-0.2;! a⤀0#1⤀+(0#,%&.0!+52%&.0!3⤀⠩05(5@#.?!_(5@.&.(52#-#(.&!K?!!!! !!!_(5@.&.(52#-#(.&!T?!!J)&+#,98B⤀⤀2&⤀$! (FLN1, FLNA) J)+9⤀$!2#$⤀.$⤀!CHaNC&#x-0.2;! 7PJ=8#+4.+D&⤀!$⤀#j%0⤀$?!=)l! ⤀![HIL&#x-0.2;! B.+,⤀8S50.+!BS[&#x-0.2;! 7PJ=8,⤀0⤀6⤀&&.0!2/$-⤀+⤀$#$!_aSB8K&#x-0.2;! M4((*V88Q"M(*(+7"%(*3(4F"69Q,3(Q"d6-G"nppq" 7J=`!=)+#+!0⤀,⤀@(50O!CHaRCaT⤀! C%D$;!BP&#x-100;eB\! _bXA?!P⤀+j!;#,05@3(3.&;#.!"X_&#x-0.2;=! 7PJ=8,350⤀5.(3⤀(5$#$!SCAST&#x-0.2;! Allan-Herndon (MCT8, SLC16A2) X0⤀.D+⤀!(0.+$@50⠩0!2⤀',#⤀+,/![PXRCM&#x-0.2;! A.+5+!,.02#5;/5@.(3/!PCJaT&#x-0.2;! C0($?!a=aa!$/+(3⤀(.$⤀!$%@⤀0.,D1#(/!a=a[K&#x-0.2;! 78&#+9⤀2!X50+⤀&#.!2⤀!P.+-⤀![JXKPK?![JXKC&#x-0.2;! _@#(j8I.1⤀--#.!be?!P%W.+!J`A

KT?!S_aC&#x-0.2;! JkAC[!SXX[&#x-0.2;! H%0+⤀0?!7PJ=83/205,⤀@3.&/8! 6.$.&!-.+-&#.!,.&,#',.D5+!! 7PJ=83/@5-5+.2#$;8(0⤀;50!XfP尀"尀! 7PJ=8+.#&!2/$(05@3/8$⤀#j%0⤀$!f"`TC&#x-0.2;! XLMR-macrocephaly-large ears (BRWD3) 7PJ=8;.,05,⤀@3.&/8J.04.+5#2!3.6#(%$!oASSXL&#x-0.2;! X30#$D.+$5+?!C+-⤀&;.+8 ⤀!![PXLCR&#x-0.2;! benP%W.+!@3⤀+5(/@⤀!fabV"&#x-0.2;! e0.3.;!,5&565;.!ke"aK&#x-0.2;! C%D$;!=aPKU&#x-0.2;! 7PJ=8$350(!$(.(%0⤀8;%$,&⤀!E.$D+-!B7bh&#x-0.2;! Cantagrel spastic paraplegia (KIAA2022) 78&#+9⤀2!mCXH`=P83/205,⤀@3.&%$!bCBX"&#x-0.2;! J#(5,35+20#.&!⤀+,⤀@3.&5@.(3/!BAfbCK&#x-0.2;! X3#/5+56%!7PJ=!e=kCV&#x-0.2;! =)+@⤀++#+- ?![%(3⤀0&.+28 S..+ ?! X⤀0⤀605@.&.(5,.02#., !S.;⤀&⤀?! e5&.6# 8k(58S.&&?! a50⠩5%$ ! }"aꄀ8K! 11.23 11.22 11.21 7PJ=83/@⤀0⤀9@&⤀:#.8$⤀#j%0⤀$!C=Se`bL&#x-0.2;! e5&(j!a_=XB&#x-0.2;! H%0+⤀0!;.,05,⤀@3.&/!SfY`K&#x-0.2;! !a섀K[T! `

@#&⤀@$/8;⤀+(.&!0⤀(.02.D5+!&#;#â ©2!(5!4⤀;.&⤀$!aXASKL&#x-0.2;! k,3(3/5$#$!45&&#,%&.0#$?!.(0#,3#.?!@35(5@356#.!J"Ha[T&#x-0.2;! !H⠀44,*3":A-;*i(Q"D⠀*⠀"Q8⤀,D⠀"7,*"7,6⤀⠀"Q;⤀⠀,⤀⠀" X-linked mental retardation (XLMR) ! X-linked intellectual disability(XLID) 撎�ience intellectuelle ' Mecp2 duplication in males: infantile hypotonia , severe mental retardation, autism, poor speech development, recurrent infections, epilepsy, progressive spasticity, developmental regression X-linked gene dosage matters! Yet Mecp2 can escape from XCI in the female brains? Mecp2 escape from X-inactivation in a subset of cells in the brain in vivo (Where, When, How, Why⤀ J#,⤀ ! 405; !CG! "#02 ! RN&1$85F[O' ;#,) ] 'L⤀*`2'&%'#6Q'⤀@+'+*6'G&2&%'89ADU' ! e⤀+⤀0.() !25%6&)8 (0.+$-⤀+#, ! ;#,) !.+2! 2)0#1⤀ ! B[X$ !! R *2G*/2G U' ! A⤀⠩0;#+⤀ !(3⤀! @0â¤

€$)+,⤀ !.+2!&5,.D5+!54!25%6&⤀8 &.6⤀&⤀2 ! ,)&&$ ! ! A)'+) !(3⤀! )@#-)+)D, ! &.+2$,.@⤀ ! .$$5,#.()2 ! E#(3 ! N&1$8 !⤀$,.@⤀! X3ka ! .z⤀0 ! ':)2 ! +%,&)# ! $50D+- �!! ! ! A)'+) !(3⤀! -)+)D, ! 0⤀*%#0⤀;⤀+($ !450!⤀$,.@⤀]!,#$!.+2! (0.+$ !i! E/)44'# %"'%"'%("(*% -4)"(4- %,'-%FEG% -4)"(4- % HEG# N&1$8' .5 $#/2% ' H_a=_! N&1$8 ! Early post natal (P6) brain: Mecp2 escape was only seen in SVZ Ð in ~20% Sox2 positive (neural stem?) cells /,)7⠀*3 "./!A#O@="8*" ,Q6-3 " H4,;* ")(7+8*)" Gendrel et al, Dev. Cell 2014 E. Heard, February 12 th , 2018 Giorgetti et al, Nature 2016 Formation of TAD accompanies Mecp2 escape on the Xi in NPCs Which cells escape and why in vivo ? What is the chromatin and topological state of Mecp2 escapee cells in vivo ? Therapeutic targeting strategy for Mecp2 reactivation in Rett픀s syndrome? Cambiaghi et al, 200

0 Anhidrotic ectodermal dysplasia (EDA) ꔀ X-linked disorder in which males are severely affected, have no sweat glands whatsoever, few teeth, little hair, and other malformations ꔀ Females can also be affected, but the effects are much milder: for example, they have patches of skin with or without sweat glands, owing to random X inactivation and cellular mosaicism . The EDA gene encodes the Ectodysplasin -A(EDA- A) protein which regulates ectodermal appendage formation. It픀s murine homolog is the Tabby locus . In 1875, Darwin described a disorder that appeared in each generation of one family's male members, affecting some but sparing others: "...small and weak incisor teeth ... very little hair on the body ... excessive dryness of the skin .... Though the daughters in the ... family were never affected, they transmit the tendency to their sons; and no cas

e has occurred of a son transmitting it to his sons." Charles Darwin (1809-1882) ! ! Epigenetic drugs? (but non-speci�c effects⤀ ! CRISPR/dCas9 delivery of transcriptional activators to the silent Mecp2 allele ! Or of architectural proteins to promote TAD formation P⤀!$/+205;⤀!2⤀!=)l!(5%,3⤀! %+)!4);;⤀!$%0!KU!UUU?! C1⤀,!2⤀$!$/;@(~;⤀$!2⤀!(/@⤀! .%D$D*%⤀! ! Reversing Mecp2 silencing on the inactive X chromosome E. Heard, February 19 th , 2018 =BC!a5&!kk! C,! SVI尀! ;)T! C,! C,! C,! SVI尀! ;)V! C7" STC!! f6! SVITN! ;)V! SVIL! ;)T! S\ITU;⤀K! C,D1⤀!7! k+.,D1⤀!7! 7#$⠀ !=BC! ! h8;⤀(3/&!,/(5$#+⤀!! ! 3**$/2GdX!K56/V&'0%)@1%@⤀&尀' SVITN ;)V! SVIL;⤀T! Reactivation from the Xi ./!" C8-"OO" ? ? SVI尀;⤀! SVnS\C,! 3/2&#G&50$&1/b1'X[0尀' M$&1/#6/]&"'1⤀*+#^2'0%#%&尀' TF ? STCI! KKRf6! Precise timing and cellular context of Mecp2

reactivation will be critical (NB dosage sensitivity of Mecp2 during development: Mecp2 duplication syndrome⤀ Modeling Rett syndrome in CynomolgusMonkeys E. Heard, February 19 th , 2018 _0+#(3#+⤀!(0.+$,.06.;/&.$⤀!2⤀',#⤀+,/!_HX&#x-0.2;! a35$@35-&/,⤀0.()!9#+.$⤀!2⤀',#⤀+,/!aeIK&#x-0.2;! [(5,,5!25$![.+(5$!IkCCKTUT&#x-0.2;! 7PJ=8,&⤀z!&#@n@.&.()!aSbM&#x-0.2;! `@#&⤀@$/n;.,05,⤀@3.&/![ZBK&#x-0.2;! K ! V ! T ! h ! T ! M ! K ! K ! K ! T ! T ! R ! T ! N ! T ! ! T ! V ! 22.3 22.2 22.1 21.3 21.2 21.1 11.4 11.3 11.1 21.1 21.2 21.3 22.1 22.2 22.3 X5{+8P5E0/!=[IT&#x-0.2;! C.0$95-!beAZ&#x-0.2;! H⤀&⤀,.+(3%$83/@5$@.2#.$!JkAK&#x-0.2;! a/0%1.()!2⤀3/205-⤀+.$⤀!2⤀',#⤀+,/!aASCK&#x-0.2;! e&/,⤀05&!9#+.$⤀!2⤀',#⤀+,/!eIA&#x-0.2;! A%,3⤀++⤀!;%$,%&.0!2/$(05@3/!AJA&#x-0.2;! J5+5.;#+⤀!5:#2.$⤀8C!2⤀',#⤀+,/!JC_C&#x-0.2;! B500#)!BA&#x-100;a! aâ

¤€&#j.)%$8J)0j6.,3⤀0!aPa&#x-0.2;! J5308H0.+⤀6W.)0-!AAa?!HkJJMC&#x-0.2;! 78&#+9⤀2!&#$$⤀+,⤀@3.&/!AX&#x-0.2;7! P5E⤀!_X=PK&#x-0.2;! [#;@$5+8e5&.6#8"⤀3;⤀&!eaXV&#x-0.2;! P⤀$,38B/3.+!Sa=H&#x-0.2;! b0.-#&⤀!7C!bJ=K&#x-0.2;! J%,5@5&/$.,,3.0#25$#$!kkC!kA[&#x-0.2;! J/5(%6%&.0!;/5@.(3/!JHJK&#x-0.2;! C20⤀+5&⤀%952/$(05@3/!C"XAK&#x-0.2;! 78&#+9⤀2!3/205,⤀@3.&/8JC[C!$@⤀,(0%;!PKXC&#x-0.2;J! .(m F"CC_A:"?_'%CnBo" k+,5+D+⤀+D.!@#-;⤀+D!B`J_?!kI"Ie&#x-0.2;! A/$9⤀0.(5$#$!,5+-⤀+#(.!AIXK&#x-0.2;! 7PJ=8S/@5(5+#,!b.,#⤀$! ! 8(3.&.$$⤀;#.!;⤀+(.&!0⤀(.02.D5+?!! X.0@⤀+â ©08Y.j#0#?!S5&;⤀$8e.+-?!X3%2&⤀/!P5E0/?!! Q%6⤀0-8J.0$#2#p&#x-0.2;?![;#(38b#+⤀;.+8J/⤀0$p&#x-0.2;! 7Ba?!7ST&#x-0.2;! 7PJ=85@D,!.(05@3/!CeH=T&#x-0.2;! a.0D+-(5+?!Y⤀$(?!a05%2?!7PCe!C&#x-0.2;=7! !! "|0W⤀$5+8b50$$;.+8P⤀3;.++!aSbR&#x-0.2;! _0.&84.,#.&82#-#(.&!k!_bAK&#x-0.2;! [@⤀0;#+⤀!$/+(3.$⤀!2â

¤€',#⤀+,/![J[&#x-0.2;! 7PJ=n-05E(3!350;5+⤀!2⤀',#⤀+,/![_7V&#x-0.2;! a⤀0#1⤀+(0#,%&.0!+52%&.0!3⤀⠩05(5@#.?!_(5@.&.(52#-#(.&!K?!!!! !!!_(5@.&.(52#-#(.&!T?!!J)&+#,98B⤀⤀2&⤀$! (FLN1, FLNA) J)+9⤀$!2#$⤀.$⤀!CHaNC&#x-0.2;! 7PJ=8#+4.+D&⤀!$⤀#j%0⤀$?!=)l! ⤀![HIL&#x-0.2;! B.+,⤀8S50.+!BS[&#x-0.2;! 7PJ=8,⤀0⤀6⤀&&.0!2/$-⤀+⤀$#$!_aSB8K&#x-0.2;! M4((*V88Q"M(*(+7"%(*3(4F"69Q,3(Q"d6-G"nppq" 7J=`!=)+#+!0⤀,⤀@(50O!CHaRCaT⤀! C%D$;!BP&#x-100;eB\! _bXA?!P⤀+j!;#,05@3(3.&;#.!"X_&#x-0.2;=! 7PJ=8,350⤀5.(3⤀(5$#$!SCAST&#x-0.2;! Allan-Herndon (MCT8, SLC16A2) X0⤀.D+⤀!(0.+$@50â ©0!2⤀',#⤀+,/![PXRCM&#x-0.2;! A.+5+!,.02#5;/5@.(3/!PCJaT&#x-0.2;! C0($?!a=aa!$/+(3⤀(.$⤀!$%@⤀0.,D1#(/!a=a[K&#x-0.2;! 78&#+9⤀2!X50+⤀&#.!2⤀!P.+-⤀![JXKPK?![JXKC&#x-0.2;! _@#(j8I.1⤀--#.!be?!P%W.+!J`AKT?!S_aC&#x-0.2;! JkAC[!SXX[&#x-0.2;! H%0+⤀0?!7PJ=83/205,⤀@3.&/8! 6.$

.&!-.+-&#.!,.&,#',.D5+!! 7PJ=83/@5-5+.2#$;8(0⤀;50!XfP尀"尀! 7PJ=8+.#&!2/$(05@3/8$⤀#j%0⤀$!f"`TC&#x-0.2;! XLMR-macrocephaly-large ears (BRWD3) 7PJ=8;.,05,⤀@3.&/8J.04.+5#2!3.6#(%$!oASSXL&#x-0.2;! X30#$D.+$5+?!C+-⤀&;.+8 ⤀!![PXLCR&#x-0.2;! benP%W.+!@3⤀+5(/@⤀!fabV"&#x-0.2;! e0.3.;!,5&565;.!ke"aK&#x-0.2;! C%D$;!=aPKU&#x-0.2;! 7PJ=8$350(!$(.(%0⤀8;%$,&⤀!E.$D+-!B7bh&#x-0.2;! Cantagrel spastic paraplegia (KIAA2022) 78&#+9⤀2!mCXH`=P83/205,⤀@3.&%$!bCBX"&#x-0.2;! J#(5,35+20#.&!⤀+,⤀@3.&5@.(3/!BAfbCK&#x-0.2;! X3#/5+56%!7PJ=!e=kCV&#x-0.2;! =)+@⤀++#+- ?![%(3⤀0&.+28 S..+ ?! X⤀0⤀605@.&.(5,.02#., !S.;⤀&⤀?! e5&.6# 8k(58S.&&?! a50⠩5%$ ! }"aꄀ8K! 11.23 11.22 11.21 7PJ=83/@⤀0⤀9@&⤀:#.8$⤀#j%0⤀$!C=Se`bL&#x-0.2;! e5&(j!a_=XB&#x-0.2;! H%0+⤀0!;.,05,⤀@3.&/!SfY`K&#x-0.2;! !a섀K[T! `@#&⤀@$/8;⤀+(.&!0⤀(.02.D5+!&#;#⠩2!(5!4⤀;.&⤀$!aXASKL&#x-0.2;! k

,3(3/5$#$!45&&#,%&.0#$?!.(0#,3#.?!@35(5@356#.!J"Ha[T&#x-0.2;! !H⠀44,*3":A-;*i(Q"D⠀*⠀"Q8⤀,D⠀"7,*"7,6⤀⠀"Q;⤀⠀,⤀⠀" X-linked mental retardation (XLMR) ! X-linked intellectual disability(XLID) genes: Why so Many? ! Genetic disability that is X-linked is more readily detectable in males due to haploid state (no second copy)? ! The X has been proposed to have up to 3 times the density of brain genes (those essential for normal brain development) as the autosomes ! Due to natural selection on genes important for neuronal functions: behaviour in males & females? ! Almost 50% of the genes on the X are expressed in the brain and in testis줠⃒brains and balls팀 theoryÉ !H⠀44,*3":A-;*i(Q"D⠀*⠀"Q8⤀,D⠀"7,*"7,6⤀⠀"Q;⤀⠀,⤀⠀" X-linked Genes and their proposed roles in ÒIntelligence팀? ! .&&⤀&⤀$!450!.+/!-⤀+⤀!5+!(3⤀!7!,305;5$5;⤀!0⤀&.()2!(5!#

+⠩&&#-⤀+,⤀!E5%&2!6⤀! +50;.&&/!2#$(0#6%⠩2!450!4⤀;.&⤀$!#G⤀G?!;5$(!E5%&2!6⤀!3⤀⠩05j/-5%$⠩O!#+! ,5+(0.$(?!(3⤀0⤀!.0⤀!+5!3⤀⠩05j/-5⠩$!450!;.&⤀$?!$5!;.&⤀$!.0⤀!2#$(0#6%⠩2! 6#;52.&&/ !.(!(3⤀!35;5j/-5⠩!⤀:(0⤀;⤀$?!(3%$!#+,0⤀.$#+-!1.0#.+,⤀G !H⠀44,*3":A-;*i(Q"D⠀*⠀"Q8⤀,D⠀"7,*"7,6⤀⠀"Q;⤀⠀,⤀⠀" 1. Many genetic defects affecting general intelligence are located on the X chromosome and hence are observed more often in males. 2. Some of these loci are implicated i渠퐀푳pecial abilities픀픀 affecting general intelligence, both throughout the distribution and at the extremes, and that, for at least some features of general intelligence, males show greater variance than females ( ie extreme alleles:⃒genius팀 genes⤀ 3. Analysis of two data sets leads to conclusion that genes involved in general intelligence are overrep

resented on the X chromosome 4. Propose that epigenetic and genetic regulatory mechanisms and genetic and co- evolutionary processes that underpin sex differences in patterns and differences in ability and that these provide opportunities for rapid evolutionary response to changing circumstance. XLID affects 30%퀀50% more males than females, and a large number of X-linked pedigrees exist for this condition. However, autosomal genes associated with XLID are likely to be underrepresented - more difficult to detect them; Although analysis of XLID mutations and sex chromosome anueploidies supports the contribution of X-linked genes to a wide range of developmental features relevant to the brain and cognition, there is no simple way to predict whether the 퐀wild type픀픀 allele of a XLID gene will enhance IQ, even though they may be necessary for 퐀normal픀픀 brain developme

nt! .&&⤀&⤀$!450!.+/!-⤀+⤀!5+!(3⤀!7!,305;5$5;⤀!0⤀&.()2!(5!#+⠩&&#-⤀+,⤀!E5%&2!6⤀! +50;.&&/!2#$(0#6%⠩2!450!4⤀;.&⤀$!#G⤀G?!;5$(!E5%&2!6⤀!3⤀⠩05j/-5%$⠩O!#+! ,5+(0.$(?!(3⤀0⤀!.0⤀!+5!3⤀⠩05j/-5⠩$!450!;.&⤀$?!$5!;.&⤀$!.0⤀!2#$(0#6%⠩2! 6#;52.&&/ !.(!(3⤀!35;5j/-5⠩!⤀:(0⤀;⤀$?!(3%$!#+,0⤀.$#+-!1.0#.+,⤀G ! Genes that arise with male advantage, in comparison with those that arise with female disadvantage, will benefit from being X linked because their immediate expression in males is not masked by the presence of a second X. ! Evidence for accumulation of 툀male advantageous팀 genes on the X in mice: 10 of the 12 spermatogenesis genes detected were found to be located on the X ⠀Wang, Page, 2001⤀ & in Humans ⠀Ross et al, 2005⤀ remarkable concentration of X-linked testis-associated genes. ! Might X-linked genes that impact

on intelligence promote reproductive success in males ⠀sexual selection⤀? ! Might X-linked genes that escape from XCI confer a reproductive advantage to females? ! Much more difficult to prove! X-linked Genes and their proposed roles in ÒIntelligence팀? ! Genes Escaping X-Inactivation Are Commonly Related to Mental Impairment Many X chromosome ploidy alterations (including XXY and XXX, XXXX, XXXXX) are associated with learning impairments ( Rooman et al. 2002). Indeed, this may be the only consistent feature of polyX karyotypes ( Rooman et al. 2002). As all but one X is inactivated, the phenotype of X polysomies is often thought to re�ect the action of genes that escape X-inactivation. X-linked gene defects have long been considered to be important causes of mental retardation - ! mental retardation is signi�cantly more co/Users/ edith / Dropbox /C

amera Uploads/2018-01-16 09.07.35.jpg - ! mmon in males than in females - ! Clinical observations and linkage studies in families revealed that X-linked mental retardation (XLMR) is a highly heterogeneous condition. - ! The most common form of XLMR Ñ the Fragile X (Fra(X)) mental-retardation syndrome⃑  is associated with a cytogenetic marker in the distal region of the long arm of the X chromosome, which was shown to coincide with the map position of the underlying gene defect, and eventually this led to the cloning of the FMR1 gene6. - ! Since then, the number of cloned XLMR genes has been increasing exponentially. Are genes the escape X inactivation under selection? ! E. Heard, February 19 th , 2018 E. Heard, February 19 th , 2018 ꔀPervasive gender bias in the frequency of diagnosis of numerous disorders. ꔀ Identi�cation of biological variables provides diagn

ostic value and insight into disease aetiology . ꔀ Hormonal effects versus sex chromosome complement? ( ie XY, XX, escapees etc Sex Differences in Neurological functions? ! ! Autism spectrum disorder is diagnosed in boys four tæ¼ �ve times more often than girls ! Schizophrenia manifests differently in men and women across lifespan ! Unipolar depression and PTSD are up to twice as frequent in women and girls. This may be skewed by social factors such as willingness to seek treatment. ! Differences in drug and alcohol abuse in men and women are speculated to be based in sex differences in risk-seeking and reward systems. More Next Week Cours V Le chromosome X et les maladies autoimmunes AnnŽe 2017-2018 : 툀Le chromosome X - paradigme de la 枎溎tique et l햎pi枎netique CHAIRE₃PIG茀N茀TIQUE ET M茀MOIRE CELLULAIRE 26 暎vri