Motor protein KIF13B orchestrates hepatic metabolism to prevent metabolic dysfunction-associated fatty liver disease.

BACKGROUND: Kinesin family member 13B (KIF13B), a crucial motor protein, exerts multiple cellular biological functions. However, the implication of KIF13B in metabolic dysfunction-associated fatty liver disease (MAFLD) has not been explored yet. This study aimed to investigate KIF13B's role and underlying mechanism in MAFLD and proposes it as a potential pharmacological target. METHODS: We assessed KIF13B expression in MAFLD patients and rodent models. The roles of Kif13b in lipid metabolism and MAFLD were investigated using whole-body Kif13b knockout mice, hepatocyte-specific Kif13b-deficient mice and hamsters exposed to different diets. The underlying mechanisms by which Kif13b governed hepatic lipid homeostasis and MAFLD progression were explored in vitro. Finally, the Kif13b's impact on atherosclerotic development was studied in the context of MAFLD. RESULTS: KIF13B expression was reduced in patients and murine models with MAFLD. Rodents with global or liver-specific knockout of the Kif13b gene exhibit spontaneous hepatic steatosis, which is further exacerbated by different overnutrition diets. Overexpression of human KIF13B by lentivirus effectively prevented metabolic dysfunction-associated steatohepatitis (MASH) in methionine-choline-deficient diet (MCD)-fed mice. Furthermore, Kif13b deficiency accelerates atherosclerosis in the context of MAFLD. Mechanistically, Kif13b depletion increases hepatic lipid synthesis and impairs mitochondrial oxidative phosphorylation. Further screening reveals that Kif13b interacts with AMP-activated catalytic subunit alpha 1 (AMPKα1) to regulate the phosphorylation of AMPKα1, governing mitochondrial homeostasis and suppressing sterol regulatory element binding protein 1 (Srebp1)-mediated de novo lipogenesis in the liver. CONCLUSION: This work establishes a causal relationship between KIF13B deficiency and MAFLD, emphasizing KIF13B as a potential therapeutic target for treating MAFLD.