Calcium/calmodulin-dependent protein kinase (CaMK) Iα mediates the macrophage inflammatory response to sepsis

Abstract

Dysregulated Ca(2+) handling is prevalent during sepsis and postulated to perpetuate the aberrant inflammation underlying subsequent organ dysfunction and death. The signal transduction cascades mediating these processes are unknown. Here, we identify that CaMKIα mediates the Mϕ response to LPS in vitro and the inflammation and organ dysfunction of sepsis in vivo. We show that LPS induced active pThr(177)-CaMKIα in RAW 264.7 cells and murine peritoneal Mϕ, which if inhibited biochemically with STO609 (CaMKK inhibitor) or by RNAi, reduces LPS-induced production of IL-10. Transfection of constitutively active CaMKIα (CaMKI293), but not a kinase-deficient mutant (CaMKI293(K49A)), induces IL-10 release. This production of IL-10 is mediated by CaMKIα-dependent regulation of p38 MAPK activation. CaMKIα activity also mediates the cellular release of HMGB1 by colocalizing with and regulating the packaging of HMGB1 into secretory lysosomes. During endotoxemia, mice receiving in vivo CaMKIα(RNAi) display reduced systemic concentrations of IL-10 and HMGB1 in comparison with mice receiving NT(RNAi). These data support the biological relevance of CaMKIα-dependent IL-10 production and HMGB1 secretion. In a CLP model of sepsis, CaMKIα(RNAi) mice display reduced systemic concentrations of IL-10, IL-6, TNF-α, and HMGB1 in comparison with NT(RNAi) mice, which correlate with reductions in the development of renal dysfunction. These data support that CaMKIα signaling is integral to the Mϕ responding to LPS and may also be operant in vivo in regulating the inflammation and organ dysfunction consequent to sepsis.

CaMKIV-Dependent Preservation of mTOR Expression Is Required for Autophagy during Lipopolysaccharide-Induced Inflammation and Acute Kidney Injury

“…Peritoneal Mφ were isolated from C57BL/6 or CaMKIV −/− mice by lavaging the peritoneal cavity with five 5mL (25mL total) aliquots of 4°C PBS. (26, 33) The lavage was centrifuged at 300g for 5 minutes, and the cells were resuspended in RPMI supplemented with 10% fetal calf serum, 50U/mL penicillin, and 50μg/mL streptomycin and plated. Selected cell populations were treated with STO609 (10μM) for 1-4 hours or MG132 (10μM) for 6 hours, as described in the figure legends.…”

Calcium/Calmodulin-dependent Protein Kinase Kinase 2: Roles in Signaling and Pathophysiology

“…CaMKIV regulates survival of activated dendritic cells and the amplitude of the antibody response induced by vaccines (62,63). CaMKI has been implicated in TLR4 (Toll-like receptor 4) signaling, as well as in the inflammatory response induced by sepsis (64), and AMPK plays an important role in the inflammatory response (65). Together, these findings suggest that CaMKK2 could be involved in the control of blood cell formation and inflammatory response.…”

Redox Control of Microglial Function: Molecular Mechanisms and Functional Significance

“…Similarly, inactivation of calcium-calmodulin-dependent kinase 1 is achieved by S-glutathionylation of the active site cysteine (Cys 179 ) (120). In macrophages, this kinase mediates the in vitro response to LPS and may also operate in vivo to regulate inflammation and organ dysfunction arising from sepsis (366). Similarly, most members of the PKC family of proteins contain several cysteine-rich regions in their catalytic and regulatory domains and, as such, are likely targets of modification by thiolation.…”