Mitochondrial protein Mrpl13 regulates zebrafish liver development through the mTORC1-mitochondrial homeostasis pathway

The liver is the largest metabolic organ in the human body, performing functions as metabolism, secretion, immunity, and detoxification. Due to the high energy demand, liver cells are rich in mitochondria. Mitochondrial homeostasis is crucial for liver development and function, yet the molecular pathways linking mitochondrial dysfunction to liver defects remain incompletely understood. In this study, using the zebrafish model, we show that loss of Mrpl13, a component of the mitochondrial ribosomal subunit, results in pronounced abnormalities in liver development. The deficiency of Mrpl13 disrupts mitochondrial homeostasis, as evidenced by fragmentated mitochondria, impaired energy metabolism, excessive reactive oxygen species, and lipid accumulation in liver cells. Notably, loss of Mrpl13 triggers mTORC1 signaling, and treatment with the mTORC1 inhibitor rapamycin significantly alleviates liver developmental defects, suggesting that mTORC1 signaling mediates the role of Mrpl13 in regulating mitochondrial homeostasis and liver development. Overall, our findings reveal a regulatory axis involving Mrpl13, mTORC1, and mitochondrial homeostasis during liver development, providing a theoretical basis for exploring therapeutic strategies for liver defects associated with mitochondrial dysfunction.