Many X-linked microRNAs escape meiotic sex chromosome inactivation

Nat Genet. 2009 Apr;41(4):488-93. doi: 10.1038/ng.338. Epub 2009 Mar 22.


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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Chromosomes, Human, X*
  • Chromosomes, Human, Y
  • Female
  • Gene Silencing
  • Humans
  • Male
  • Meiosis
  • Mice
  • MicroRNAs / genetics*
  • Spermatocytes / physiology
  • X Chromosome
  • X Chromosome Inactivation / genetics*
  • Y Chromosome


  • MicroRNAs