Knockdown of Telethonin Reduces Contractions and Provokes Aberrant Ca2+-waves in Human iPS Cell-induced Cardiomyocytes.

OBJECTIVES

Dilated cardiomyopathy (DCM) is one of the leading causes of heart failure. To date, 48 genes are known to be associated with DCM. Telethonin, encoded by the TCAP gene, is a Z-disk protein that composes cytoskeletal structures and facilitates various signaling pathways in cardiomyocytes. At least, six TCAP variants have been found in patients with DCM. We sought to investigate the role of TCAP in cardiac function using TCAP-knockdown (KD) iPS cell (iPSC)-induced cardiomyocytes (CMs).

METHODS &

RESULTS

To investigate the role of TCAP in cardiomyocytes, the TCAP gene was knocked down in human iPS cells established from a healthy subject (201B7) using the CRISPR-Cas9 genome editing. The expressions of TCAP mRNA and telethonin were confirmed by RT-qPCRs and Western blot, respectively. The 201B7 wild type (WT) and the TCAP-knocked down (KD) cells were differentiated into cardiomyocytes (CMs). The contractility measured by a high-resolution block matching-based optical flow technique showed that all contractility parameters, including contraction velocity, relaxation velocity, and contraction-relaxation duration, were decreased in the KD-CMs (n = 54) compared to the WT-CMs (n = 24) (WT vs. KD: 51.28 ± 22.82 vs. 29.11 ± 22.83 µm/s, p < 0.001; 22.05 ± 8.85 vs. 12.48 ± 8.85 µm/s, p < 0.001; 0.82 ± 0.12 vs. 0.58 ± 0.12 s, p < 0.001). Ca2+-imaging studies showed aberrant Ca2+-waves in the KD-CMs.

CONCLUSIONS

We found that TCAP-KD in human iPS cell-induced CMs impairs contraction, induces triggered activities, and abnormal Ca2+-waves, which is consistent with the phenotypes of DCM.