Inhibition of Troponin C Production Without Affecting Other Muscle Protein Synthesis by the Antisense Oligodeoxynucleotide

The effect of blocking expression of a specific gene with antisense phosphodiester oligodeoxynucleotides on the coordinate regulation of myogenesis was studied. Different regions of both fast and slow troponin C (TnC) mRNAs were targeted for binding of the antisense oligomer. The 5‵-cap region of both mRNAs was found to be the most effective target for inhibiting the expression of these genes. Approximately 40%–60% inhibition of expression of a specific isoform of TnC was achieved. However, inhibition of the TnC expression did not appreciably alter the pattern of myogenesis of mouse C₂C₁₂ cells. The differentiated murine muscle cells were able to cope with this reduced level of the target gene expression by antisense phosphodiester oligomers. We have also used a phosphorothioate oligomer targeted against a common sequence within the coding region of both fast and slow TnC mRNAs. This oligomer was found to be ineffective in blocking TnC gene expression.