eNOS deletion impairs mitochondrial quality control and exacerbates Western diet-induced NASH

Area of Science:

• Hepatology
• Mitochondrial Biology
• Molecular Medicine

Background:

• Mitochondrial dysfunction is key in nonalcoholic steatohepatitis (NASH).
• Dysregulated mitochondrial quality control contributes to liver disease progression.
• Identifying regulators of mitochondrial quality control is crucial for NASH treatment.

Purpose of the Study:

• To identify novel regulators of mitochondrial quality control in hepatocytes.
• To investigate the role of endothelial nitric oxide synthase (eNOS) in hepatic mitochondrial function and NASH.
• To elucidate the mechanisms by which eNOS influences liver health.

Main Methods:

• Utilized eNOS knockout mouse models fed a Western diet.
• Employed magnetic activated cell sorting for primary hepatocyte purification.
• Performed in vitro siRNA-mediated knockdown of eNOS in hepatocytes.
• Assessed mitochondrial biogenesis, autophagy, mitophagy, and fatty acid oxidation markers.
• Investigated the activation of nuclear factor erythroid 2-related factor 2 (NRF2).

Main Results:

• eNOS knockout mice showed increased susceptibility to diet-induced hepatic inflammation and fibrosis.
• Mitochondria from eNOS knockout mice exhibited reduced markers of biogenesis and turnover (e.g., PPARγ coactivator-1α, BNIP3, LC3).
• Primary hepatocytes lacking eNOS had impaired fatty acid oxidation and mitophagic response.
• eNOS deficiency prevented the activation of the transcription factor NRF2 in hepatocytes.

Conclusions:

• Hepatocellular eNOS is a critical regulator of mitochondrial quality control and function.
• eNOS deficiency impairs mitochondrial turnover and fatty acid metabolism, exacerbating NASH.
• eNOS plays a protective role in the liver by maintaining mitochondrial homeostasis and activating NRF2.