KPNβ1 promotes palmitate-induced insulin resistance via NF-κB signaling in hepatocytes.

It has been intensively studied that inflammation contributes to the insulin resistance development in obesity-induced type 2 diabetes mellitus (T2DM). In this study, we assessed the effect of karyopherin β1 (KPNβ1) in hepatic insulin resistance and the underlying mechanisms using high-fat diet (HFD) fed mice and palmitate (PA)-stimulated hepatocytes (HepG2). KPNβ1 expression is increased in the HFD fed mice liver. PA upregulated KPNβ1 expression in HepG2 cells in a time-dependent manner. PA also increased pro-inflammatory cytokines expression, including tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), and interleukin 1β (IL-1β). KPNβ1 knockdown reversed PA-induced pro-inflammatory cytokines expression and insulin-stimulated glucose uptake in HepG2 cells. In addition, KPNβ1 knockdown reduced intracellular lipid accumulation. Mechanistically, KPNβ1 transports nuclear factor kB (NF-κB) p65 from the cytoplasm to the nucleus to increase pro-inflammatory genes expression. In summary, KPNβ1 acts as a positive regulator in the NF-κB pathway to enhance palmitate-induced inflammation response and insulin resistance in HepG2 cells.