|
Comment |
Characterization of a Novel Mouse Gene Encoding an SYCP3-Like Protein That Relocalizes from the XY Body to the Nucleolus During Prophase of Male Meiosis I. Tsutsumi M et al. Xlr6 is a novel but yet uncharacterized X-linked gene that is upregulated in meiotic prophase I during mouse spermatogenesis. Xlr6 belongs to the Xlr gene family, which includes a component of the axial/lateral element of the synaptonemal complex, Sycp3, and its transcripts are abundant in the fetal ovary and adult testis. Immunostaining and Western blot analysis demonstrate a diffuse localization pattern for this protein in the nucleus and an association with chromatin during the leptotene and zygotene stages. In males, XLR6 accumulates at the XY body of early to mid pachytene spermatocytes, although the Xlr6 gene is subjected to meiotic sex chromosome inactivation. During the late pachytene and diplotene stages, the XLR6 protein re-localizes from the XY body to the nucleolus, and eventually disappears by diakinesis. In females, XLR6 disappears at the pachytene stage, whilst it accumulates at the unpaired chromosomes occasionally observed in wild-type female mice. Although the amino acid sequence of XLR6 has a high similarity with SYCP3, its distinct localization pattern and dynamism suggest a unique chromatin modification function that leads to the transcriptional repression of ribosomal DNA in addition to sex chromosome genes.
|