# HOIL-1L deficiency induces cell cycle alteration which causes immaturity of skeletal muscle and cardiomyocytes

## TL;DR

This study shows that a deficiency in HOIL-1L leads to cell cycle issues that impair the development of muscle and heart cells, contributing to myopathy and dilated cardiomyopathy.

## Contribution

The study identifies HOIL-1L as a key regulator of cell cycle and maturation in muscle and heart cells using both mouse and human cell models.

## Key findings

- HOIL-1L deficiency causes mitotic cell accumulation and impaired differentiation in myotubes.
- Patient-derived heart cells show abnormal morphology and excessive multinucleation.
- HOIL-1L is essential for proper cell cycle regulation and maturation of muscle and heart cells.

## Abstract

HOIL-1L deficiency was recently reported to be one of the causes of myopathy and dilated cardiomyopathy (DCM). However, the mechanisms by which myopathy and DCM develop have not been clearly elucidated. Here, we sought to elucidate these mechanisms using the murine myoblast cell line C2C12 and disease-specific human induced pluripotent stem cells (hiPSCs). Myotubes differentiated from HOIL-1L-KO C2C12 cells exhibited deteriorated differentiation and mitotic cell accumulation. CMs differentiated from patient-derived hiPSCs had an abnormal morphology with a larger size and were excessively multinucleated compared with CMs differentiated from control hiPSCs. Further analysis of hiPSC-derived CMs showed that HOIL-1L deficiency caused cell cycle alteration and mitotic cell accumulation. These results demonstrate that abnormal cell maturation possibly contribute to the development of myopathy and DCM. In conclusion, HOIL-1L is an important intrinsic regulator of cell cycle-related myotube and CM maturation and cell proliferation.