Antisense-mediated regulation of exon usage in the elastic spring region of Titin modulates sarcomere function.

Summary

The authors identify TTN-AS1-276 as the predominant TTN antisense transcript in the human heart, upregulated in heart failure, and demonstrate that its knockdown reduces RBM20–TTN pre-mRNA interaction, decreases I-band exon skipping, lowers N2B isoform expression, and improves sarcomere mechanics. The data support antisense-mediated control of TTN splicing as a regulator of cardiomyocyte passive stiffness and diastolic performance.

Key Findings

• TTN-AS1-276 is the predominant TTN NAT in the human heart and is upregulated in heart failure.
• Knockdown of TTN-AS1-276 reduces RBM20–TTN pre-mRNA interaction and decreases I-band exon skipping, lowering N2B isoform expression.
• Sarcomeres became longer with preserved alignment and showed improved fractional shortening and relaxation times after TTN-AS1-276 knockdown.
• Effects were independent of sense–antisense exon overlap and polymerase II elongation rate.

Clinical Implications

Modulating TTN-AS1-276 or its interaction with RBM20 may reduce passive stiffness and improve diastolic function, suggesting an RNA-targeted strategy for HFpEF.

Limitations

• Predominantly in vitro/iPS-CM and human tissue studies without in vivo therapeutic modulation
• Translational dosing, delivery, and off-target effects of antisense manipulation remain untested

Future Directions

In vivo validation of TTN-AS1-276 targeting, development of delivery platforms, and evaluation in HFpEF models with diastolic dysfunction.