EXPRESSION AND POTENTIAL FUNCTION OF THE C-MOS PROTOONCOGENE IN HUMANEGGS

Objective: To investigate the expression and possible function of the c-mos proto-oncogene in human eggs. Design: Eggs obtained as discarded material from assisted reproductive technology procedures were analyz ed for c-mos messenger RNA by reverse transcriptase-polymerase chain r eaction. As an approach to investigating c-mos function, we measured m aturation-promoting factor (MPF) activity (histone H1 kinase) in eggs without and with inhibition of protein synthesis. Detection of RNA tra nscripts of c-raf was included as control. Results: Transcripts of c-m os were detected in small fractions of individual eggs, indicating tha t e-nos is abundantly transcribed. Inhibition of protein synthesis res ulted in loss of MPF, leading to chromatin decondensation and reformat ion of a nucleus. C-raf maternal messages were also detectable in indi vidual human eggs. Conclusion: The c-mos proto-oncogene is an abundant maternal message in human eggs as in other species. The effects of in hibiting protein synthesis in human eggs are similar to those obtained in mouse and Xenopus eggs, either as a consequence of protein synthes is inhibition or specific ablation of c-mos RNA by injection of anti-s ense oligonucleotides. The c-mos gene product is thus likely to play a critical role in human oocyte meiosis by regulating the activity of M PF.