Cell cycle genes c-mos and cyclin-B1 are expressed in a specific pattern in human oocytes and preimplantation embryos.
Little is known about the molecular mechanisms governing the development of human oocyte and pre-embryo. We characterized the expression pattern of c-mos, cyclin B1 and beta-actin mRNA in oocytes and granulosa cells from human and monkey, and in human early embryos, using both qualitative and semi-quantitative reverse transcriptase polymerase chain reaction. The proto-oncogene c-mos was expressed in an oocyte-specific manner and no mRNA for c-mos could be detected in the granulosa cells. Similarly, strong expression of cyclin-B1 was seen in the oocytes. In human pre-embryos, the expression of cyclin-B1 and beta-actin increased from the 6-cell stage onwards, indicating active transcription and thus activation of embryonic genome either at or before the 6-cell stage. The expression of c-mos was transient and very little c-mos mRNA could be detected in the human embryos beyond the 6-cell stage. Thus, both its time-specific and site-specific expression suggest meiosis-specific functions for the proto-oncogene c-mos in human oocytes. As judged by the disappearance of c-mos, the maternal pool of mRNA seems to be degraded towards the 6- to 8-cell stage. The transient expression of c-mos and high levels of cyclin-B1 mRNA suggest that mechanisms similar to those found in lower organisms govern the growth and development of the human oocyte and preimplantation embryo.
Heikinheimo
O
O
Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk 23507, USA.
Lanzendorf
S E
SE
Baka
S G
SG
Gibbons
W E
WE
D000199:Actins / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D001755:Blastocyst / Q000378:metabolism*; D015139:Blotting, Southern; D002453:Cell Cycle / Q000235:genetics*; D016213:Cyclins / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D016258:Genes, mos; D006107:Granulosa Cells / Q000378:metabolism; D006801:Humans; D008252:Macaca fascicularis; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger / Q000378:metabolism; D012194:RNA-Directed DNA Polymerase
D000199:Actins; D016213:Cyclins; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger; D012194:RNA-Directed DNA Polymerase