Molecular cloning of CSF-1 receptor from rat myoblasts. Sequence analysis and regulation during myogenesis.
We have isolated and sequenced a cDNA (mrfms) encoding rat c-fms gene (CSF-1 receptor) from proliferating L6 alpha 1 myoblasts. The predicted amino acid sequence was highly identical with the c-fms protein found in monocytes and macrophages (98, 76 and 84% identity from mouse, cat and human c-fms proteins, respectively). The mechanisms responsible for the regulation of mrfms gene expression during myogenesis were examined. Mrfms products were observed during proliferation of L6 alpha 1 myoblasts and were downregulated during differentiation. Run-on transcription assays demonstrated that the mrfms gene was transcriptionally active only in undifferentiated myoblasts. These findings suggested that mrfms levels in L6 alpha 1 myoblasts are controlled by transcriptional mechanisms. The half-life of mrfms transcripts was found to be at least 5 hr while inhibition of protein synthesis with cycloheximide (CHX) decreased this half-life to 30 min without changes in the rate of mrfms gene transcription. In addition oncogenic transformation of L6 alpha 1 myoblasts by the v-fms induced constitutive upregulation of mrfms mRNAs, and nuclear run-on assays demonstrated that mrfms transcription was not growth-factor dependent. Furthermore, these findings with others previously published indicate that mrfms gene products may play a role in the normal and neoplastic growth of muscular cells.
Borycki
A G
AG
Laboratoire d'Oncologie Moléculaire UA 1158--URA 126 du CNRS, Institut Gustave Roussy 39, Villejuif, France.
Guillier
M
M
Leibovitch
M P
MP
Leibovitch
S A
SA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002460:Cell Line; D003001:Cloning, Molecular; D003513:Cycloheximide / Q000494:pharmacology; D004247:DNA; D003609:Dactinomycin / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D009132:Muscles / Q000166:cytology / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic / Q000502:physiology*; D014170:Transformation, Genetic / Q000502:physiology
D012333:RNA, Messenger; D003609:Dactinomycin; D004247:DNA; D003513:Cycloheximide; D016186:Receptor, Macrophage Colony-Stimulating Factor