Cell type-specific expression of endogenous cardiac Troponin I antisense RNA in the neonatal rat heart.

Since the number of detected natural antisense RNA is growing, investigations upon the expression pattern of the antisense RNA become more important. As we focused our work on natural occurring antisense transcripts in human and rat heart tissues, we were interested in the question, whether the expression pattern of antisense and sense RNA can vary in different cell types of the same tissue. In our previous analysis of total neonatal rat heart tissue, we demonstrated the co-expression of both cTnI RNA species in this tissue.

Regulation of the human atrial myosin light chain 1 promoter by Ca2+-calmodulin-dependent signaling pathways.

We investigated expression regulation of the human atrial myosin light chain 1 (hALC-1) gene using a cardiomyocyte H9c2 cell line stably transfected with a construct consisting of the human ALC-1 promoter cloned in front of the luciferase gene (H9c2T1). H9c2T1 cells were stimulated with vasopressin, which is known to induce cardiomyocyte hypertrophy and to activate a panel of signaling pathways. Those pathways involved in hALC-1 promoter activity regulation were dissected by using pharmacological inhibitor substances.

Role of endogenous antisense RNA in cardiac gene regulation.

Endogenous antisense RNA has been detected for a range of eukaryotic genes and now appears to be a common phenomenon in mammalian cells. Its abundance compared to levels of its complementary sense mRNA indicates that antisense RNA may be involved in posttrancriptional regulation of a gene. In general a downregulating effect on gene expression has been demonstrated or suggested.

Detection of a novel sense-antisense RNA-hybrid structure by RACE experiments on endogenous troponin I antisense RNA.

Conformational changes in the troponin/tropomyosin complex significantly alter the mechanical properties of cardiac muscle. Phosphorylation of cardiac troponin I, part of the troponin/tropomyosin complex, reduces calcium affinity, which leads to increased relaxation of cardiac muscle. Because cardiac troponin I plays a central role in tuning the heart to different work demands, detailed knowledge of troponin I protein regulation is required.

Cardiac troponin I sense-antisense RNA duplexes in the myocardium.

Natural antisense RNA is now thought to regulate, at least in part, a growing number of eukaryotic genes. It is becoming increasingly apparent that such endogenous antisense RNA molecules may modulate gene expression in a manner analogous to synthetic oligomers. Here, we report the detection of antisense-orientated RNA transcripts of cardiac specific troponin I in rat and human myocardium.