Expression of RUSH transcription factors in developing and adult rabbit gonads

The RUSH transcription factors 1 alpha and 1 beta bind to the Rabbit Uterog lobin promoter and are members of the SWI/SNF complex that facilitates tran scription by remodeling chromatin (Helicase). To characterize gonadal expre ssion of RUSH, a cRNA probe that recognizes both isoforms was used for in s itu hybridization studies. We found RUSH mRNA to be abundant in Sertoli cel ls from embryonic, neonatal, prepubertal, and pubertal rabbit testes. In ad ults, RUSH mRNA was detected in tubules with preleptotene spermatocytes and mature spermatids lining the lumen. However, RUSH was undetectable in tubu les that contained leptotene spermatocytes and that lacked mature spermatid s, In females, RUSH was expressed in presumptive granulosa cells of embryon ic and neonatal ovaries before follicle organization, abundant RUSH mRNA wa s detected in granulosa and theca cells surrounding preantral follicles of prepubertal and adult ovaries. Expression of RUSH remained high in granulos a cells of antral follicles in mature ovaries but was negligible in late-st age atretic follicles and in corpora lutea. Western blot analysis confirmed the RUSH-1a isoform predominated in both testicular and ovarian tissues. T he expression pattern of RUSH indicates transcriptional activity in Sertoli cells and during multiple stages of differentiating granulosa cells, espec ially those of primordial follicles, which heretofore were considered to be dormant.