EXPRESSION OF RBM IN THE NUCLEI OF HUMAN GERM-CELLS IS DEPENDENT ON ACRITICAL REGION OF THE Y-CHROMOSOME LONG ARM

The association of abnormal spermatogenesis in men with Y chromosome d eletions suggests that genes important for spermatogenesis have been r emoved from these individuals. Recently, genes encoding two putative R NA-binding proteins (RBM and DAZ/SPGY) have been mapped to two differe nt regions of the human Y chromosome. Both of these genes encode prote ins that contain a single RNA recognition motif and a (different) inte rnally repeating sequence. Y-linked RBM homologues are found in all ma mmalian species. We have raised an antiserum to RBM and used it to sho w that RBM is a nuclear protein expressed in fetal, prepubertal, and a dult male germ cells. The distribution of RBM protein in the adult cor relates with the pattern of transcriptional activity in spermatogenesi s, suggesting that RBM is involved in the nuclear metabolism of newly synthesized RNA. RBM sequences are found on both arms of the Y chromos ome making genotype-phenotype correlations difficult for this gene fam ily. To address the location of the functional genes and the consequen ces of their deletion, we examined a panel of men with Y chromosome de letions and known testicular pathologies using this antiserum. This ap proach enabled us to map a region of the Y chromosome essential for RB M expression. In the absence of detectable RBM expression we see stage s of germ cell development up to early meiosis, but not past this poin t into the haploid phase of spermatogenesis.