The depletion of serine beta-lactamase-like protein (LACTB) ameliorates metabolic dysfunction-associated steatotic liver disease by reducing ubiquitin-mediated degradation of carnitine palmitoyltransferase 2.

[AIMS] Metabolic dysfunction-associated steatotic liver disease (MASLD) represents one of the most common chronic liver disorders worldwide, and its incidence continues to rise each year. Serine β-lactamase-like protein (LACTB) is a serine protease that plays a crucial role in lipid metabolism and hepatocellular carcinoma, but its function in MASLD remains unclear. Therefore, the study aims to elucidate the effect and mechanism of LACTB in the progression of MASLD.

[MATERIALS AND METHODS] The expression of LACTB in liver tissues from MASLD patients and high-fat diet (HFD) fed mice was assessed. Both in vivo and in vitro models were established to examine the role and molecular mechanisms of LACTB in MASLD.

[RESULTS] LACTB protein levels were upregulated in the liver tissues from MASLD patients and HFD-fed mice. LACTB overexpression exacerbated hepatic steatosis, insulin resistance, and inflammation in HFD-fed mice. Conversely, LACTB knockdown improved these phenotypes. Mechanistically, LACTB interacted with CPT2 and promoted its ubiquitin-mediated degradation. The effect of LACTB in hepatocellular lipid metabolism was dependent on CPT2.

[CONCLUSIONS] Our findings indicate that LACTB is a novel regulatory factor in MASLD by influencing the ubiquitin-mediated degradation of CPT2 to participate in disease progression. These findings may provide a novel potential therapeutic strategy for MASLD.