Developmental regulation of creatine kinase isoenzymes in myogenic cell cultures from chicken. Levels of mRNA for creatine kinase subunits M and B.
During the first 2 days of culture of myogenic chicken cells only minute amounts of mRNA for a subunit of creatine kinase, M-CK, could be found in cultures from the 3rd and 4th day; however, a dramatic increase of mRNA for the muscle-specific M-CK was observed. The mRNA for B-CK, another subunit of creatine kinase, was readily detectable in young cultures increased up to the 3rd day in culture but decreased significantly 1 day later. The comparison of the ratios of mRNA concentrations for M-CK and B-CK in polysomal and total cellular RNA did not reveal significant differences in polysomal and total cellular RNA from 24-, 48-, and 68-h cultures, indicating that specific accumulation of a nonpolysomal form containing translatable mRNA for M-CK prior to its appearance in the polysomes does not seem to represent a major mechanism of regulation. In RNA from cells grown in 5-bromo-2'-deoxyuridine (BrdUrd) for 3 days and subcultured into the same medium for another 3 days only mRNA for B-CK was found. If cells, however, were subcultured into standard medium both mRNAs, the one for B-CK and the one for M-CK could be detected. BrdUrd inhibition seems to affect only the mRNA for M-CK and not the one for B-CK. Removal of BrdUrd from the cultures probably allows new transcription or processing of mRNA for M-CK, or both.
D000818:Animals; D002454:Cell Differentiation; D002459:Cell Fusion; D002478:Cells, Cultured; D002642:Chick Embryo; D003402:Creatine Kinase / Q000096:biosynthesis*; D007527:Isoenzymes / Q000096:biosynthesis*; D007700:Kinetics; D009132:Muscles / Q000201:enzymology*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism*; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism
D007527:Isoenzymes; D012333:RNA, Messenger; D003402:Creatine Kinase