Translation of c-myc mRNA is required for its post-transcriptional regulation during myogenesis.
During the differentiation of C2 myoblasts into differentiated myotubes, there is a marked decrease in the abundance of c-myc mRNA. c-myc transcription initiation and elongation do not change significantly, but the turnover of c-myc transcripts appears to be accelerated during differentiation. We examined the expression of several recombinant c-myc genes introduced into C2 cells by stable transfection and found that mRNAs containing the c-myc protein-coding region of exons 2 and 3 are appropriately regulated; the upstream c-myc sequences, the long leader sequence encoded by c-myc exon 1, and the 3' untranslated region are dispensible for proper regulation. Regulation appears to affect c-myc transcripts that are bound to polyribosomes, and the mRNA from a gene with a point mutation in the translation initiation codon is no longer properly regulated. We conclude that down-regulation of c-myc expression during myogenesis is post-transcriptional and requires the presence of sequences encoding the c-myc protein in a form that can be translated.
Wisdom
R
R
Department of Medicine, University of California, San Francisco.
Lee
W
W
D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D005786:Gene Expression Regulation; D016259:Genes, myc; D006801:Humans; D009132:Muscles / Q000166:cytology; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D014176:Protein Biosynthesis; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D015183:Restriction Mapping; D014158:Transcription, Genetic; D014162:Transfection
D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger