Functional analysis of TTN uORFs reveals context-dependent translational regulation.

Disruption of TTN uORFs does not increase titin expression in human cardiomyocytes, revealing context-dependent regulation of TTN translation.

• Why it matters: Understanding TTN regulation is crucial because heterozygous truncating variants cause familial dilated cardiomyopathy, and therapies targeting gene expression could offer new treatments.
• What they did: The study used luciferase reporter assays and CRISPR-Cas9 editing in human-induced pluripotent stem cell-derived cardiomyocytes to investigate TTN uORFs' role in regulating titin expression.
• The result: Findings show that although uORFs repress translation in reporter systems, disrupting them in the endogenous TTN locus does not elevate titin levels, emphasizing the importance of validating regulatory elements within their native cellular context.