title: CaMKKβ-dependent activation of AMP-activated protein kinase is critical to suppressive effects of hydrogen sulfide on neuroinflammation.
abstract: OBJECTIVE
  The manner in which hydrogen sulfide (H2S) suppresses neuroinflammation is poorly understood. We investigated whether H2S polarized microglia to an anti-inflammatory (M2) phenotype by activating AMP-activated protein kinase (AMPK).
  
  
  RESULTS
  Three structurally unrelated H2S donors (5-(4-hydroxyphenyl)-3H-1,2-dithiocyclopentene-3-thione [ADT-OH], (p-methoxyphenyl) morpholino-phosphinodithioic acid [GYY4137], and sodium hydrosulfide [NaHS]) enhanced AMPK activation in BV2 microglial cells in the presence and absence of lipopolysaccharide (LPS). The overexpression of the H2S synthase cystathionine β-synthase (CBS) in BV2 cells enhanced endogenous H2S production and AMPK activation regardless of LPS stimulation. On LPS stimulation, overexpression of both ADT-OH and CBS promoted M2 polarization of BV2 cells, as evidenced by suppressed M1 and elevated M2 signature gene expression. The promoting effects of ADT-OH on M2 polarization were attenuated by an AMPK inhibitor or AMPK knockdown. Liver kinase B1 (LKB1) and calmodulin-dependent protein kinase kinase β (CaMKKβ) are upstream kinases that activate AMPK. ADT-OH activated AMPK in Hela cells lacking LKB1. In contrast, both the CaMKKβ inhibitor and siRNA abolished ADT-OH activation of AMPK in LPS-stimulated BV2 cells. Moreover, the CaMKKβ inhibitor and siRNA blunted ADT-OH suppression on M1 gene expression and enhancement of M2 gene expression in LPS-stimulated BV2 cells. Moreover, ADT-OH promoted M2 polarization of primary microglia in an AMPK activation- and CaMKKβ-dependent manner. Finally, in an LPS-induced in vivo neuroinflammation model, both ADT-OH and NaHS enhanced AMPK activation in the brain area where microglia were over-activated on LPS stimulation. Furthermore, ADT-OH suppressed M1 and promoted M2 gene expression in this in vivo model.
  
  
  CONCLUSIONS
  CaMKKβ-dependent AMPK activation is an unrecognized mechanism underlying H2S suppression on neuroinflammation.
authors.affiliation: 1 Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Institute of Neuroscience, Soochow University , Suzhou, China .
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Zhou
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Cao
authors.forename: Guizhen
authors.initials: G
authors.lastname: Ao
authors.forename: Lifang
authors.initials: L
authors.lastname: Hu
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.forename: Jian
authors.initials: J
authors.lastname: Wu
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Wang
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Jin
authors.forename: Shuli
authors.initials: S
authors.lastname: Zheng
authors.forename: Xuechu
authors.initials: X
authors.lastname: Zhen
authors.forename: Nabil J
authors.initials: NJ
authors.lastname: Alkayed
authors.forename: Jia
authors.initials: J
authors.lastname: Jia
authors.forename: Jian
authors.initials: J
authors.lastname: Cheng
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000818:Animals; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase / Q000378:metabolism*; D002478:Cells, Cultured; D004789:Enzyme Activation; D006862:Hydrogen Sulfide / Q000378:metabolism*; D007249:Inflammation / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000378:metabolism; D019636:Neurodegenerative Diseases / Q000378:metabolism*
chemical_list: D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase; D055372:AMP-Activated Protein Kinases; D006862:Hydrogen Sulfide