Cell interactions and actin synthesis in mammalian oocytes

Abstract

In this study, we have examined the profiles of proteins synthesized by mammalian oocytes in the presence and absence of cumulus cells. The results show that the patterns of protein synthesis are broadly similar in cumulus-enclosed and denuded oocytes, but that as a consequence of removing the cumulus cells, the presence of a 45,000-dalton band is greatly reduced. This band, identified by comigration studies on two-dimensional polyacrylamide gels as actin, is strongly synthesized in both isolated cumulus cells and in oocytes labeled in the presence of cumulus cells, but is only weakly synthesized by oocytes incubated in the absence of cumulus cells. We suggest that the presence of newly synthesized actin in the oocyte is dependent upon cellular cooperation between the cumulus cells and oocytes.