GRK6 palmitoylation increasing its membrance translocation promotes LPS-induced inflammation by PI3K/ AKT pathway in kuppfer cells.

Background: G protein-coupled receptor kinases 6 (GRK6) is one kinase of GPCRs, previous studies have shown that GRK6 is involved in the regulation of inflammatory processes. However, the role of GRK6 in inflammation is not well understood and what is the effect of its palmitoylation modification on inflammatory response in macrophage are still largely unknown.

Methods: LPS stimulated Kupffer cells to simulate inflammatory injury model. SiGRK6 and GRK6 lentiviral plasmids were used to alter cellular GRK6 levels. Subcellular localization of GRK6 was detected using Membrane and Cytoplasmic Protein Extraction Kit and immunofluorescence. Palmitoylated Protein Assay Kit (Red) and modified Acyl-RAC method were used to detect palmitoylation levels.

Results: GRK6 mRNA and protein expression decreased in LPS-induced inflammatory response in Kupffer cells (P < 0.05). Overexpression of GRK6 promoted inflammatory response, while silencing GRK6 reduced inflammatory response (P < 0.05). In terms of molecular mechanisms, LPS induced increased palmitoylation of GRK6 and promoted the translocation of GRK6 to cell membranes (P < 0.05). Subsequently, GRK6 functioned through the PI3K/ AKT signaling pathway (P < 0.05). Inhibition of palmitoylation level of GRK6 can inhibit its membrane translocation and reduce inflammatory response (P < 0.05).

Conclusion: Inhibition of palmitoylation level of GRK6 might relieve LPS-induced inflammation in Kupffer cells by blocking GRK6 membrane translocation and subsequent inflammatory signaling pathway, providing a theoretical basis for targeting GRK6 to regulate inflammation.