Death-associated protein kinase 1 mediates interleukin-1\u03b2 production through regulating inlfammasome activation in Bv2 microglial cells and mice

Limin Song,Wei Xiong,Shanglong Yao,Lisha Hu,Lei Pei,Shangwen Pan,Yan Wu,You Shang,Min Liu

doi:10.1038/s41598-018-27842-y

Abstract

Interleukin-1β (IL-1β) plays a crucial role in mediating inflammation and innate immunity response in the central nervous system. Death-associated protein kinase 1 (DAPK1) was shown to be involved in several cellular processes. Here, we investigated the effects of DAPK1 on IL-1β production in microglial cells. We used a combination of in vitro (Bv2 microglial cell cultures) and in vivo (mice injected with amyloid-β (Aβ)) techniques to address the role of caspase-1 activation in release of IL-1β. DAPK1 involvement was postulated through genetic approaches and pharmacological blockade of this enzyme. We found that Aβ25–35 stimulation induced IL-1β production and caspase-1 activation in LPS-primed Bv2 cells and mice. DAPK1 knockdown and catalytic activity inhibition reduced IL-1β maturation and caspase-1 activation, nevertheless, DAPK1 overexpression attenuated these effects. Aβ25–35-induced lysosomal cathepsin B leakage was required for DAPK1 activation. Furthermore, repeated DAPK1 inhibitor treatment ameliorated the memory impairment in Aβ25–35-injected mice. Taken together, our findings suggest that DAPK1 facilitates Aβ25–35-induced IL-1β production through regulating caspase-1 activation in microglial cells.

Highlights

Death-associated protein kinase 1 (DAPK1) is a member of death domain-containing calcium/calmodulin-dependent serine/threonine kinase family that plays a critical role in regulating several cellular processes including cell apoptosis and autophagy[1,2,3,4]
The results showed that CA-074Me treatment had no effect on DAPK1 expression, but abolished the increase in the protein levels of p-myosin II regulatory light chain (MLC) induced by Aβ25–35 (Fig. 5A), which is indicative of less DAPK1 activation
We showed that DAPK1 which was activated downstream of Aβ25–35-triggered lysosomal cathepsin B leakage, promoted caspase-1 activation and IL-1β production in Bv2 cells and mice

Summary

Introduction

Death-associated protein kinase 1 (DAPK1) is a member of death domain-containing calcium/calmodulin-dependent serine/threonine kinase family that plays a critical role in regulating several cellular processes including cell apoptosis and autophagy[1,2,3,4]. Aβ deposition recruits and activates microglia, which results in the production of various pro-inflammatory mediators that lead to neuronal injury[8,9,10,11,12]. IL-1β is synthesized as the inactive precursor pro-IL-1β via the nuclear factor-κB (NF-κB) pathway and processed into its mature form by caspase-1 which itself is tightly controlled by intracellular inflammasomes[15]. The first step is priming through up-regulating the expression of NLRP3 via the NF-κB pathway[17]; the second step is exposing to the following or simultaneous NLRP3-specific activators that induce the assembly of the inflammasome, which leads to the autocatalytic activation of caspase-118. Our findings demonstrate that DAPK1, which is activated in the lysosomal protease cathepsin B-dependent pathway, functions as a positive regulator of the inflammasome activation. DAPK1 inhibitor administration reduces IL-1β production through inhibiting NLRP3 inflammasome activation and improves cognitive outcomes in Aβ25–35-injected mice

Methods

Results

Conclusion