title: Many X-linked microRNAs escape meiotic sex chromosome inactivation.
abstract: Meiotic sex chromosome inactivation (MSCI) during spermatogenesis is characterized by transcriptional silencing of genes on both the X and Y chromosomes in mid-to-late pachytene spermatocytes. MSCI is believed to result from meiotic silencing of unpaired DNA because the X and Y chromosomes remain largely unpaired throughout first meiotic prophase. However, unlike X-chromosome inactivation in female embryonic cells, where 25-30% of X-linked structural genes have been reported to escape inactivation, previous microarray- and RT-PCR-based studies of expression of >364 X-linked mRNA-encoding genes during spermatogenesis have failed to reveal any X-linked gene that escapes the silencing effects of MSCI in primary spermatocytes. Here we show that many X-linked miRNAs are transcribed and processed in pachytene spermatocytes. This unprecedented escape from MSCI by these X-linked miRNAs suggests that they may participate in a critical function at this stage of spermatogenesis, including the possibility that they contribute to the process of MSCI itself, or that they may be essential for post-transcriptional regulation of autosomal mRNAs during the late meiotic and early postmeiotic stages of spermatogenesis.
authors.affiliation: Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA.
authors.forename: Rui
authors.initials: R
authors.lastname: Song
authors.forename: Seungil
authors.initials: S
authors.lastname: Ro
authors.forename: Jason D
authors.initials: JD
authors.lastname: Michaels
authors.forename: Chanjae
authors.initials: C
authors.lastname: Park
authors.forename: John R
authors.initials: JR
authors.lastname: McCarrey
authors.forename: Wei
authors.initials: W
authors.lastname: Yan
mesh_terms: D000818:Animals; D041321:Chromosomes, Human, X; D041322:Chromosomes, Human, Y; D005260:Female; D020868:Gene Silencing; D006801:Humans; D008297:Male; D008540:Meiosis; D051379:Mice; D035683:MicroRNAs / Q000235:genetics*; D013090:Spermatocytes / Q000502:physiology; D014960:X Chromosome; D049951:X Chromosome Inactivation / Q000235:genetics*; D014998:Y Chromosome
chemical_list: D035683:MicroRNAs