Influence of mechanical activity, adrenergic stimulation, and calcium on the expression of myosin heavy chains in cultivated neonatal cardiomyocytes.
It is generally accepted that mechanical stress of cardiomyocytes increases RNA and protein synthesis of myosin heavy chain (MHC) quantitatively but it is still a matter of debate whether MHC gene expression is also changed qualitatively. We investigated expression of MHC genes of spontaneously contracting neonatal cardiomyocytes experimentally arrested by permanent depolarization [potassium chloride (KCl)] as well as by electromechanical uncoupling [2,3 butanedione monoxime (BDM)]. Relative distribution of MHC mRNA isoforms (alpha and beta) was studied by quantitative polymerase chain reaction. Expression of MHC isoenzymes was the same in contracting (34.5% beta-MHC) and arrested (40.5% and 33.0% beta-MHC in KCl and BDM, respectively) cardiomyocytes. However, treatment with phenylephrine for the same period increased significantly beta-MHC expression to 55%. We conclude that hormonal factors rather than Ca2+ or mechanical stress regulate qualitatively MHC gene expression.
Luther
H P
HP
Max Delbrück Centre for Molecular Medicine, Berlin, Germany.
Hille
S
S
Haase
H
H
Morano
I
I
D018663:Adrenergic Agents / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002478:Cells, Cultured; D017931:DNA Primers; D003931:Diacetyl / Q000031:analogs & derivatives / Q000494:pharmacology; D005786:Gene Expression Regulation; D009206:Myocardium / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011189:Potassium Chloride / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic
D018663:Adrenergic Agents; D017931:DNA Primers; D012333:RNA, Messenger; C004717:diacetylmonoxime; D011189:Potassium Chloride; D018995:Myosin Heavy Chains; D003931:Diacetyl; D002118:Calcium