Identification of a cis acting element responsible for muscle specific expression of the c-mos protooncogene.
A series of deletion constructs of the 5' flanking region of rat c-mos gene was positioned upstream to the CAT gene and transfected into muscle and non-muscle cells. CAT activities revealed that a region located downstream of a TATA box and containing the proximal transcription start site is the muscle c-mos promoter. This promoter is more efficient in L6 alpha 1 myoblasts than in L6 alpha 1 myotubes but not in C3H10T1/2 cells. Gel shift assays demonstrated that nuclear proteins from myoblasts and myotubes formed complexes migrating differently. Footprinting analyses showed that nuclear proteins from L6 alpha 1 myoblasts protected a DNA fragment located at position nt -979 to nt -938 relative to the first ATG of the rat c-mos ORF while nuclear proteins from myotubes protected the DNA between nt -998 to nt -928. Furthermore one of protein - DNA complexes containing the proximal transcription start site, included a consensus sequence TGTC(AGT/TCG)CC(A/T)G present in the initiator element (Inr) of several genes. Southwestern blot analysis pointed to a 82kDa polypeptide as a potential candidate for trans acting factor in myoblasts. In L6 alpha 1 myotubes this polypeptide is replaced by other proteins of 40-42kDa and 82kDa. An interplay between these two complexes may constitute a developmental as well as a physiologically regulated mechanism that modulates c-mos expression during the early stages of myogenesis.
Lenormand
J L
JL
Laboratoire d'Oncologie Moléculaire, UA 1148, URA 126 du CNRS, Institut Gustave Roussy, Villejuif, France.
Guillier
M
M
Leibovitch
S A
SA
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004247:DNA; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation; D016258:Genes, mos; D008969:Molecular Sequence Data; D009132:Muscles / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D009928:Organ Specificity; D010455:Peptides / Q000378:metabolism; D011401:Promoter Regions, Genetic; D051381:Rats; D015183:Restriction Mapping; D012260:Ribonucleases; D014158:Transcription, Genetic
D009687:Nuclear Proteins; D010455:Peptides; D004247:DNA; D012260:Ribonucleases