Restricted expression of Ovol2/MOVO in XY body of mouse spermatocytes at the pachytene stage.

The development of multicellular organisms is controlled by sequential activation of a hierarchy of regulatory genes, which encode transcription factors having DNA-binding motifs. We previously identified a testis-specific zinc finger transcriptional factor, Ovol2/MOVO, as a mouse homologue of Drosophila Ovo. Because mice deficient in Ovol2/Movo die during early embryogenesis, its function in male germ cells has remained unknown. We have recently succeeded in preparing anti-Ovol2/MOVO antiserum for immunohistochemical use. In the present study, we demonstrated that Ovol2/MOVO protein started to be expressed in male germ cells at 2 weeks after birth and that Ovol2/MOVO expression was restricted to the XY body in spermatocytes at the pachytene stage. In a reporter assay, Ovol2/MOVO repressed the histone H1t promoter activity in the spermatogenic cell line GC-2spd. These results suggest that Ovol2/MOVO may play an important role in the XY body during spermatogenesis, possibly in the processes of XY body formation and meiotic sex chromosome inactivation.