Maternal Rnf12/RLIM is required for imprinted X-chromosome inactivation in mice.
Two forms of X-chromosome inactivation (XCI) ensure the selective silencing of female sex chromosomes during mouse embryogenesis. Imprinted XCI begins with the detection of Xist RNA expression on the paternal X chromosome (Xp) at about the four-cell stage of embryonic development. In the embryonic tissues of the inner cell mass, a random form of XCI occurs in blastocysts that inactivates either Xp or the maternal X chromosome (Xm). Both forms of XCI require the non-coding Xist RNA that coats the inactive X chromosome from which it is expressed. Xist has crucial functions in the silencing of X-linked genes, including Rnf12 (refs 3, 4) encoding the ubiquitin ligase RLIM (RING finger LIM-domain-interacting protein). Here we show, by targeting a conditional knockout of Rnf12 to oocytes where RLIM accumulates to high levels, that the maternal transmission of the mutant X chromosome (Δm) leads to lethality in female embryos as a result of defective imprinted XCI. We provide evidence that in Δm female embryos the initial formation of Xist clouds and Xp silencing are inhibited. In contrast, embryonic stem cells lacking RLIM are able to form Xist clouds and silence at least some X-linked genes during random XCI. These results assign crucial functions to the maternal deposit of Rnf12/RLIM for the initiation of imprinted XCI.
Shin
Jongdae
J
Program in Gene Function and Expression, University of Massachusetts Medical School (UMMS), Worcester, Massachusetts 01605, USA.
Bossenz
Michael
M
Chung
Young
Y
Ma
Hong
H
Byron
Meg
M
Taniguchi-Ishigaki
Naoko
N
Zhu
Xiaochun
X
Jiao
Baowei
B
Hall
Lisa L
LL
Green
Michael R
MR
Jones
Stephen N
SN
Hermans-Borgmeyer
Irm
I
Lawrence
Jeanne B
JB
Bach
Ingolf
I
D000818:Animals; D020296:Animals, Congenic; D001755:Blastocyst / Q000378:metabolism; D002460:Cell Line; D033481:Chromosomes, Mammalian / Q000235:genetics*; D020964:Embryo Loss / Q000235:genetics; D005220:Fathers; D005260:Female; D020868:Gene Silencing; D018392:Genomic Imprinting; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009035:Mothers; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated / Q000235:genetics; D012097:Repressor Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases; D014960:X Chromosome / Q000235:genetics*; D049951:X Chromosome Inactivation / Q000235:genetics*
D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D012097:Repressor Proteins; C077885:XIST non-coding RNA; C120758:Rlim protein, mouse; D044767:Ubiquitin-Protein Ligases