X chromosome inactivation in the absence of Dicer.
Dicer is central to the RNA interference (RNAi) pathway, because it is required for processing of double-stranded RNA (dsRNA) precursors into small RNA effector molecules. In principle, any long dsRNA could serve as a substrate for Dicer. The X inactive specific transcript (Xist) is an untranslated RNA that is required for dosage compensation in mammals. It coats and silences 1 of the 2 X chromosomes in female cells and initiates a chromosomewide change in chromatin structure that includes the recruitment of Polycomb proteins, but it is largely unknown how Xist RNA mediates these processes. To investigate a potential link between the RNAi pathway and X inactivation, we generated and analyzed Dicer-deficient embryonic stem (ES) cells. In the absence of Dicer, coating by Xist RNA, initiation of silencing, and recruitment of Polycomb proteins occur normally. Dicer ablation had modest effects on the steady-state levels of spliced Xist RNA. Together our data indicate that the RNAi machinery is not essential for the initiation of X inactivation.
Kanellopoulou
Chryssa
C
Dana-Farber Cancer Institute, Department of Cancer Biology, Harvard Medical School, One Jimmy Fund Way, Boston, MA 02115, USA.
Muljo
Stefan A
SA
Dimitrov
Stoil D
SD
Chen
Xi
X
Colin
Christian
C
Plath
Kathrin
K
Livingston
David M
DM
D000818:Animals; D003433:Crosses, Genetic; D053487:DEAD-box RNA Helicases / Q000172:deficiency* / Q000378:metabolism; D004318:Doxycycline / Q000494:pharmacology; D053595:Embryonic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004722:Endoribonucleases / Q000172:deficiency* / Q000378:metabolism; D005260:Female; D020868:Gene Silencing / Q000187:drug effects; D050172:Genes, X-Linked; D007178:Inbreeding; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008957:Models, Genetic; D063146:Polycomb-Group Proteins; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D043244:Ribonuclease III; D013752:Tetracycline / Q000494:pharmacology; D014960:X Chromosome / Q000235:genetics; D049951:X Chromosome Inactivation / Q000187:drug effects / Q000235:genetics*
D063146:Polycomb-Group Proteins; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D012097:Repressor Proteins; C077885:XIST non-coding RNA; D004722:Endoribonucleases; C509781:Dicer1 protein, mouse; D043244:Ribonuclease III; D053487:DEAD-box RNA Helicases; D013752:Tetracycline; D004318:Doxycycline