Leukocyte cell-derived
chemotaxin 2 (LECT2) is a recently discovered hepatokine that mediates
obesity-related metabolic disturbances. Dipeptidyl peptidase-4 (DPP-4) inhibitors are novel therapeutic agents for inflammatory disorders including
nonalcoholic fatty liver disease (
NAFLD). However, no research has examined the connections or functions of LECT2 and the novel
DPP-4 inhibitor,
gemigliptin, in
NAFLD pathogenesis. High-fat diet (HFD)-fed C57BL/6 mice were used to investigate the effect of
gemigliptin on hepatic steatosis and LECT2 expression. In the HepG2 cell line, LECT2 and
gemigliptin signaling were analyzed by Western blot. LECT2 increased
mammalian target of rapamycin (mTOR) phosphorylation,
sterol regulatory element-binding protein (SREBP)-1 cleavage,
lipid accumulation, and
insulin resistance in HepG2 cells; these events were significantly decreased by treatment with a
c-Jun N-terminal kinase (JNK) inhibitor.
Gemigliptin increased
AMP-activated protein kinase (AMPK) phosphorylation and inhibited
tumor necrosis factor (TNF) α-induced mTOR phosphorylation, SREBP-1 cleavage,
lipid accumulation, and LECT2 expression in HepG2 cells; these events were attenuated by an AMPK inhibitor.
Gemigliptin recovered TNFα-induced inhibition of
insulin receptor substrate (IRS)-1 and Akt phosphorylation that was abolished in LECT2 knockdown cells or by AMPK inhibition. In preliminary in vivo experiments,
gemigliptin induced AMPK phosphorylation and inhibited LECT2 expression in liver tissues from HFD-fed mice. Mice fed with HFD and
gemigliptin showed improved hepatic steatosis and
insulin resistance compared to HFD-fed mice.
Gemigliptin might alleviate hepatic steatosis and
insulin resistance by inhibiting LECT2 expression by AMPK-dependent and JNK-dependent mechanisms, suggesting a direct protective effect against
NAFLD progression.