Abstract
Mitochondrial dysfunction is a critical driver of metabolic dysfunction-associated steatotic liver disease (MASLD) progression to steatohepatitis (MASH), yet the mechanisms governing mitochondrial quality control in hepatocytes remain poorly defined. Here, we identify TANK-binding kinase 1 (TBK1) as an essential regulator of hepatic mitophagy and lysosomal activity. Using TBK1-deficient hepatocytes and liver-specific TBK1 knockout (LTKO) mice, we show that TBK1 loss leads to the accumulation of depolarized, ROS-producing mitochondria due to impaired mitophagy flux, including defective lysosomal degradation. Mechanistically, TBK1 is required for p62 phosphorylation at Ser403 and partially modulates mTOR signaling to preserve lysosomal acidification. Therapeutic restoration of TBK1 expression via AAV8 delivery enhanced mitophagy, reduced mitochondrial burden, and ameliorated liver fibrosis. Notably, both human samples and murine steatohepatitis models exhibited a significant decline in TBK1 kinase activity. Collectively, these findings establish TBK1 as a critical guardian of mitochondrial and lysosomal homeostasis in MASH.