GSK3?-dependent inhibition of AMPK potentiates activation of neutrophils and macrophages and enhances severity of acute lung injury.

ABSTRACT: Although AMP-activated protein kinase (AMPK) is involved in regulating carbohydrate and lipid metabolism, activated AMPK also plays an anti-inflammatory role in many cell populations. However, despite the ability of AMPK activation to diminish the severity of inflammatory responses, previous studies have found that AMPK activity is diminished in LPS-treated neutrophils and also in lungs of mice with LPS-induced acute lung injury (ALI). Since GSK3? participates in regulating AMPK activity, we examined potential roles for GSK3? in modulating LPS-induced activation of neutrophils and macrophages and in influencing severity of ALI. We found that GSK3?-dependent phosphorylation of T479-AMPK was associated with pT172 dephosphorylation and inactivation of AMPK following TLR4 engagement. GSK3? inhibitors BIO (6-bromoindirubin-3'-oxime), SB216763, or siRNA knockdown of GSK3?, but not the PI3K/AKT inhibitor LY294002, prevented Thr172-AMPK dephosphorylation. Exposure to LPS resulted in rapid binding between IKK? and AMPK?, and phosphorylation of S485-AMPK by IKK?. These results suggest that IKK?-dependent phosphorylation of S485-AMPK was an essential step in subsequent phosphorylation and inactivation AMPK by GSK3?. Inhibition of GSK3? activity delayed I?B? degradation and diminished expression of the proinflammatory TNF-? in LPS-stimulated neutrophils and macrophages. In vivo, inhibition of GSK3? decreased the severity of LPS-induced lung injury as assessed by development of pulmonary edema, production of TNF-? and MIP-2, and release of the alarmins HMGB1 and histone 3 in the lungs. These results show that inhibition of AMPK by GSK3? plays an important contributory role in enhancing LPS-induced inflammatory responses, including worsening the severity of ALI.

SUBMITTER: Park DW 

PROVIDER: S-EPMC4233296 | biostudies-literature | 2014 Nov

REPOSITORIES: biostudies-literature