EXPRESSION OF THE V-MOS ONCOGENE IN MALE MEIOTIC GERM-CELLS OF TRANSGENIC MICE RESULTS IN METAPHASE ARREST

To explore the role of pp39(mos) in male germ cell meiosis, we have co nstructed transgenic mice carrying either the c-Mos or v-Mof genes lin ked to the human male germ cell-specific phosphoglycerate kinase-2 pro moter. All male transgenic mice bearing the v-Mos but not the c-Mos co nstruct were sterile due to arrest of germ cells at metaphase I. Immun ocytochemistry performed on sections from control and c-Mos transgenic testes with eight different monoclonal and polyclonal antisera agains t either alpha-, beta- or gamma-tubulins demonstrated that all could r ecognize ML spermatocyte spindles from control and c-Mos transgenics, but only one monoclonal anti-microtubule sera decorated the spindles o f v-Mos-arrested meiotic figures. Western blot analyses with this one serum revealed a change in proteins in the v-Mos samples. Immunocytoch emistry with the MPM-2 monoclonal antibody, which is specific for epit opes phosphorylated during mitosis, demonstrated an increase in cytopl asmic and spindle-associated phosphoproteins in arrested v-Mos spermat ocytes. Western analysis with MPM-2 showed an increase in a M(r) 50,00 0-55,000 and a M(r) 25,000-29,000 protein in Mos transgenic testes whe n compared to controls. An anti-MAP kinase antibody demonstrated an in crease in all four MAP kinases in testes of transgenic mice. Thus, ove rexpression of pp39(v-mos) during male germ cell meiosis resulted in a n alteration of various cell cycle related kinases and cytostatic fact or-like arrest at MI.