Effects of the v-mos oncogene on Xenopus development: meiotic induction in oocytes and mitotic arrest in cleaving embryos.
Previous work has demonstrated that the Xenopus protooncogene mosxe can induce the maturation of prophase-arrested Xenopus oocytes. Recently, we showed that mosxe can transform murine NIH3T3 fibroblasts, although it exhibited only 1-2% of the transforming activity of the v-mos oncogene. In this study we have investigated the ability of the v-mos protein to substitute for the mosxe protein in stimulating Xenopus oocytes to complete meiosis. Microinjection of in vitro synthesized RNAs encoding either the mosxe or v-mos proteins stimulates resting oocytes to undergo germinal vesicle breakdown. Microinjection of an antisense oligonucleotide spanning the initiation codon of the mosxe gene blocked progesterone-induced oocyte maturation. When oocytes were microinjected first with the mosxe antisense oligonucleotide, and subsequently with in vitro synthesized v-mos RNA, meiotic maturation was rescued as evidenced by germinal vesicle breakdown. The v-mos protein exhibited in vitro kinase activity when recovered by immunoprecipitation from either microinjected Xenopus oocytes or transfected monkey COS-1 cells; however, in parallel experiments, we were unable to detect in vitro kinase activity associated with the mosxe protein. Microinjection of in vitro synthesized v-mos RNA into cleaving Xenopus embryos resulted in mitotic arrest, demonstrating that the v-mos protein can function like the mosxe protein as a component of cytostatic factor. These results exemplify the apparently conflicting effects of the v-mos protein, namely, its ability to induce maturation of oocytes, its ability to arrest mitotic cleavage of Xenopus embryo, and its ability to transform mammalian fibroblasts.
Freeman
R S
RS
Department of Chemistry, University of California at San Diego, La Jolla 92093.
Kanki
J P
JP
Ballantyne
S M
SM
Pickham
K M
KM
Donoghue
D J
DJ
D000818:Animals; D002455:Cell Division; D002460:Cell Line; D004625:Embryo, Nonmammalian / Q000166:cytology; D005260:Female; D015870:Gene Expression; D008540:Meiosis; D008938:Mitosis; D017232:Oncogene Proteins v-mos; D009857:Oncogenes; D009865:Oocytes / Q000166:cytology* / Q000201:enzymology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D015682:Retroviridae Proteins, Oncogenic / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014981:Xenopus
D017232:Oncogene Proteins v-mos; D015682:Retroviridae Proteins, Oncogenic; D011505:Protein-Tyrosine Kinases