To examine cardiac myosin gene structure and expression in a non-human primate model for human heart development and disease we have constructed a cDNA library from baboon atrium and used baboon β-myosin heavy chain (β-MHC)* * Abbreviations: aa, amino acids; bp, base pairs; IgG, immunoglobulin G; LMM, light meromyosin; MAb, monoclonal antibody; MHC, myosin heavy chain; nt, nucleotides. cDNA probes to isolate atrial MHC clones. The nucleotide sequence of one such clone, λBMHCα3, contains sequences that encode part of the light meromyosin region (LMM) and the 3′ untranslated region of the baboon α-MHC. To study cardiac MHC gene transcription, we constructed probes from the baboon α-MHC cDNA for S1 nuclease analyses of RNA from atria and ventricles. To examine translational regulation of cardiac MHC gene expression, we used monoclonal antibodies (MAb) against specific α- and β-MHC epitopes for Western blot analyses. In atria and ventricles from adult baboons, we detected predominantly α- and β-MHC gene transcripts, respectively. In ventricles from fetal baboons at two stages of development (140 and 160 days gestation), we also detected predominantly β-MHC gene transcripts and isoforms. To investigate changes induced by parturition, we obtained ventricles from baboons that were prematurely delivered at 140 days gestation and supported for 10 days in an extrauterine environment. In contrast to adult and fetal patterns, we observed an increase in α-MHC transcripts and isoforms in ventricles of premature baboons. Because α-MHC gene expression is increased in premature baboons (total age of 150 days) compared to their older 160 day fetal counterparts, the induction of ventricular α-MHC synthesis must have resulted from factor(s) associated with parturition or prolonged mechanical ventilation rather than at predetermined stages of gestational development.
- Mechanical ventilation
- Myosin heavy chains
ASJC Scopus subject areas
- Molecular Biology
- Cardiology and Cardiovascular Medicine