Integrated multi-omics approach revealed TTNtv c.13254T>G causing dilated cardiomyopathy in mice.

Titin-truncating variant (TTNtv) is the most common genetic cause of dilated cardiomyopathy (DCM). In the previous study, we found a novel heterozygous TTNtv c.13254T>G (p.Tyr4418Ter) associated with DCM, but lacking functional evidence. The purpose of this study is to demonstrate the pathogenicity of TTNtv c.13254T>G. We constructed a mouse model with TTNtv Y4370* on exon 45 by CRISPR/Cas9-mediated genome engineering to imitate the TTNtv. c.13254T>G. Transmission electron microscope (TEM), immunohistochemistry, western blot (WB), Transcriptome sequencing (RNA-seq), and tandem Mass Tag (TMT) proteome analysis were performed on the mutant (KO) and WT mice cardiac tissue. Multi-omics association analysis was performed to observe the damages of cardiac tissue, and changes of inflammatory factors and Titin protein. TEM results showed that TTNtv Y4370* may lead to broken myofibrils, sparse myofilament structure, and broken Z-line and H-zone in many places of cardiac tissue of KO mice. Immunohistochemistry showed a significant increase in cTnT and TNF-α expression level in KO mice cardiac tissue. RNA-seq and TMT proteome enrichment analysis further strengthened that TTNtv Y4370* led to cardiac injury and inflammatory response in KO mice. In summary, TTNtv c.13254T>G contributed to the cardiac injury, inflammatory response and construct alterations in mice, that is TTNtv c.13254T>G may cause DCM in mice. These functional evidence of TTNtv c.13254T>G have important significance for follow-up genetic research of DCM in human.