TRANSCRIPTION OF C-MOS PROTOONCOGENE IN THE PIG INVOLVES BOTH TISSUE-SPECIFIC PROMOTERS AND ALTERNATIVE POLYADENYLATION SITES

The function of the c-mos gene has been intensively studied, but its r ole in the mammal is still a subject for debate. For this reason, and because the gene is regulated posttranscriptionally, further study of the gene from other mammalian species is timely. The pig c-mos gene ha s been cloned, and the genomic sequence is presented here. The gene ha s no introns and shows close similarity to human and monkey genes, wit h striking sequence similarities in both the 5' and 3' flanking region s. The significance of this similarity in the context of gene regulati on is discussed. c-mos expression was found to be restricted to gonada l tissues in the pig. The major start sites for transcription initiati on in ovary and testis were identified by primer extension and found t o be distinct, as in the mouse. Within the ovary, expression is confin ed to oocytes. Messenger RNA is synthesized in growing oocytes, and re mains stable during oocyte maturation, but begins to be degraded in el ectrically stimulated eggs. Unexpectedly, RNase protection assays reve aled that the 3' ends of transcripts in the pig ovary are heterogeneou s, and this, together with the identification of three distinct cDNA c lones, shows that multiple polyadenylation sites are used. The signifi cance of these transcripts in terms of translational control is discus sed. (C) 1996 Wiley-Liss, Inc.