c-mos expression in mouse oocytes is controlled by initiator-related sequences immediately downstream of the transcription initiation site.

Pal SK, Zinkel SS, Kiessling AA, Cooper GM
Mol Cell Biol. 1991 11 (10): 5190-6

PMID: 1833632 · PMCID: PMC361551 · DOI:10.1128/mcb.11.10.5190

We have employed transient expression assays to analyze the sequences that direct c-mos transcription in mouse oocytes. Plasmids containing the chloramphenicol acetyltransferase (CAT) gene fused to either a 2.4-kb or a 731-bp fragment from the 5'-flanking region of c-mos produced similar levels of CAT activity when injected into nuclei of growing oocytes. BAL 31 deletions revealed that sequences up to 20 bp upstream of the major transcription start site could be removed without any significant loss of CAT activity. Promoter activity only decreased when these deletions closely approached the transcription start site, which was mapped at 53 nucleotides upstream of the first ATG in the c-mos open reading frame. On the other hand, deletion of sequences within 20 nucleotides downstream of the transcription initiation site resulted in a 10-fold reduction in CAT expression. A similar decrease in promoter activity was observed as a result of point mutations in these 5' untranslated sequences. Thus, sequences immediately downstream of the transcription start site, including a consensus sequence (PyPyCAPyPyPyPyPy) present in the initiator elements of several genes, appear to regulate c-mos expression in mouse oocytes. Reverse transcription-polymerase chain reaction analysis of RNA from injected oocytes showed that this regulation is manifest at the transcriptional level. Expression of c-mos in mouse oocytes thus appears to be directed by a simple promoter consisting only of sequences immediately surrounding the transcription start site, including an initiator element in the untranslated leader.

MeSH Terms (18)

Animals Base Sequence Cell Line Cells, Cultured Chloramphenicol O-Acetyltransferase DNA Mutational Analysis Gene Expression Regulation Genes, mos Mice Mice, Inbred Strains Microinjections Molecular Sequence Data Oocytes Plasmids Polymerase Chain Reaction Proto-Oncogene Proteins Proto-Oncogene Proteins c-mos Regulatory Sequences, Nucleic Acid

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