Analysis of sense and naturally occurring antisense transcripts of myosin heavy chain in the human myocardium

Naturally occurring antisense RNA has the potential to form a duplex with its complementary sense mRNA, thereby regulating protein expression. Previously, we demonstrated considerable amounts of endogenous antisense RNA for both alpha- and beta-myosin heavy chain (MHC) in rat heart suggesting a role in posttranscriptional MHC-regulation (Luther et al. [1997] J Mol Cell Cardiol 29(1):27-35). To evaluate whether antisense RNA is also involved in MHC regulation in human heart we analyzed ventricular myocardium transcripts in nonfailing hearts (n=3) and hearts from patients undergoing heart transplantation (n=5). Investigation of RNA by reverse transcription polymerase chain reaction (RT-PCR) detected an antisense RNA transcript for beta-MHC but none for alpha-MHC. Northern blot analysis of normal and failing hearts detected sense mRNA for beta-MHC, but not alpha-MHC suggesting no functionally relevant levels of alpha-MHC mRNA exist in the human ventricle. The results describe-for the first time-the existence of endogenous polyadenylated MHC antisense transcripts in the human heart. The potential effect of attenuating translation was shown in an in vitro translation assay using a synthetic antisense-oligonucleotide derived from the sequence of the naturally occurring antisense RNA.