Definitive expression of c-mos in late meiotic prophase leads to phosphorylation of a 34 kda protein in cultured rat spermatocytes.
To investigate the role of c-mos in rat spermatogenesis, expression of c-mos, MAP kinase kinase (MAPKK), MAP kinase (MAPK), cdc2 and protein kinase A (PKA) by spermatogenic cell culture of 14 day-old rats was examined. MAPKK and PKA expressions were constitutive, whereas the expression of MAPK and cdc2 in spermatogonia initially decreased, but later increased on meiotic maturation of spermatocytes. c-mos expression was definitive of late meiotic prophase. c-mos immunoprecipitates prepared from the c-mos-enriched fraction (pI9.0-9.6) could form complex(es) in the cultured spermatogenic cell lysates. In vitro phosphorylation of the c-mos immune complexes revealed a 34 kDa protein that was phosphorylated at serine and threonine residues as a target of the c-mos signal. Its pI value was 4.4-4.5, and cdc2 was not detected, making it different from cdc2 (p34). These results suggest that the phosphorylation of the 34 kDa protein by the c-mos signal may play a crucial role in the meiotic division of rat spermatocytes.
Nagao
Yosinobu
Y
Division of Clinical Science, Medical Research Institute, and Department of Biochemistry, Kanazawa Medical University, Uchinada, Ishikawa 920-0293, Japan. y-nag@kanazawa-med.ac.jp
D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D020935:MAP Kinase Signaling System; D008297:Male; D008540:Meiosis; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D017231:Proto-Oncogene Proteins c-mos / Q000096:biosynthesis*; D051381:Rats; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction; D013090:Spermatocytes / Q000378:metabolism*; D013912:Threonine / Q000378:metabolism; D013997:Time Factors
D013912:Threonine; D012694:Serine; D017231:Proto-Oncogene Proteins c-mos; D017868:Cyclic AMP-Dependent Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases