SPERM-1 - A POU-DOMAIN GENE TRANSIENTLY EXPRESSED IMMEDIATELY BEFORE MEIOSIS-I IN THE MALE GERM-CELL

Members of the POU-domain gene family encode for transcriptional regul atory molecules that are important for terminal differentiation of sev eral organ systems, including anterior pituitary, sensory neurons, and B lymphocytes. We have identified a POU-domain factor, referred to as sperm 1 (Sprm-1). This factor is most related to the transactivator O ct-3/4, which is expressed in the early embryo, primordial germ cells, and the egg. However, in contrast with Oct-3/4, rat Sprm-1 is selecti vely expressed during a 36- to 48-hr period immediately preceding meio sis I in male germ cells. Although the POU-domain of Sprm-1 is diverge nt from the POU-domains of Oct-1 and Oct-2, random-site-selection assa y reveals that Sprm-1 preferentially binds to a specific variant of th e classic octamer DNA-response element in which the optimal sequence d iffers from that preferred by Oct-1 and Pit-1. These data suggest that the Sprm-1 gene encodes a DNA-binding protein that may exert a regula tory function in meiotic events that are required for terminal differe ntiation of the male germ cell.