BRCA1 MESSENGER-RNA IS EXPRESSED HIGHLY DURING MEIOSIS AND SPERMIOGENESIS BUT NOT DURING MITOSIS OF MALE GERM-CELLS

The 17q-linked breast and ovarian cancer susceptibility gene (BRCA1) i s believed to function as a tumor suppressor gene (Miki et al., 1994). In this report BRCA1 RNA expression has been analysed in adult mouse tissues with detailed attention to its expression in prepuberal and ad ult testis. Measurements of BRCA1 mRNA levels in highly purified somat ic cells of the testis and in staged germ cells showed that high level BRCA1 mRNA expression is limited to the germ cells. Within the germ c ell lineage, the high level expression was detected in meiotic cells, specifically pachytene spermatocytes and in post-meiotic round spermat ids. This is in contrast to premeiotic germ cells which were found to express little or no BRCA1 mRNA. These observations, considered togeth er with recent data on the expression of BRCA1 in breast epithelium, a rgues against a function for BRCA1 in early progenitor cells in both t issues and calls attention instead to roles intimately associated with terminal differentiation or with final rounds of cell division.