Hexokinase dissociation from mitochondria promotes oligomerization of VDAC that facilitates NLRP3 inflammasome assembly and activation

Abstract

NLRP3 inflammasome activation is a highly regulated process for controlling secretion of the potent inflammatory cytokines IL-1β and IL-18 that are essential during bacterial infection, sterile inflammation, and disease, including colitis, diabetes, Alzheimer’s disease, and atherosclerosis. Diverse stimuli activate the NLRP3 inflammasome, and unifying upstream signals has been challenging to identify. Here, we report that a common upstream step in NLRP3 inflammasome activation is the dissociation of the glycolytic enzyme hexokinase 2 from the voltage-dependent anion channel (VDAC) in the outer membrane of mitochondria. Hexokinase 2 dissociation from VDAC triggers activation of inositol triphosphate receptors, leading to release of calcium from the ER, which is taken up by mitochondria. This influx of calcium into mitochondria leads to oligomerization of VDAC, which is known to form a macromolecule-sized pore in the outer membranes of mitochondria that allows proteins and mitochondrial DNA (mtDNA), often associated with apoptosis and inflammation, respectively, to exit the mitochondria. We observe that VDAC oligomers aggregate with NLRP3 during initial assembly of the multiprotein oligomeric NLRP3 inflammasome complex. We also find that mtDNA is necessary for NLRP3 association with VDAC oligomers. These data, together with other recent work, help to paint a more complete picture of the pathway leading to NLRP3 inflammasome activation.

Spatiotemporal proteomic profiling of cellular responses to NLRP3 agonists

“…Additionally, in contrast to a recent report [106], we find that both hexokinase 1 and 2 (HK1, HK2) accumulate, rather than dissociate from, the mitochondria upon inflammasome stimulation (Figures 3D-E). This effect could be due to different metabolic states between cell types, particularly with NF-κB stimulation in macrophages, so it warrants further study.…”

“…Imiquimod and its derivative CL097 activate the inflammasome in part by disrupting mitochondrial and metabolic homeostasis [55][56]. Additionally, inhibition of the electron transport chain dampens NLRP3 activation by multiple agonists [56], and mitochondria have been proposed as a site of inflammasome activation [106][107][108][109]. We thus profiled how inflammasome agonists remodel the mitochondrial proteome.…”

Therapeutic targeting of immunometabolism in Alzheimer’s disease reveals a critical reliance on Hexokinase 2 dosage on microglial activation and disease progression

“…Instead, we observed that the decreased catalytic activity of HK2 was associated with the increase in the levels of its cytosolic target IKBα, a regulatory protein that inhibits the nuclear translocation of NFKβ and the induction of the expression of inflammasome genes. In contrast, the complete deletion of HK2, overrode this mechanism by inducing mitochondrial dysfunction and inflammasome activation as previously described by Hu et al and others 13,15,17 .…”

“…Like other glycolytic enzymes, HK2 has non-metabolic roles that can impact inflammation independently of its canonical glycolytic role. HK2 binds to the outer mitochondrial membrane (OMM) through direct interaction with the voltage-dependent anion channel (VDAC) and its displacement induces the formation of a mitochondrial pore that triggers the activation of NLRP3 inflammasome 13 .…”

Adaptive Nanoparticle-Mediated Modulation of Mitochondrial Homeostasis and Inflammation to Enhance Infected Bone Defect Healing

“…And the generation of ROS and M1 polarization can promote each other, leading to further exacerbation of the immune regulation. Additionally, the accumulation of mitochondrial ROS (mtROS) triggers nucleotide-binding domain and leucine-rich repeat containing receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome activation, ultimately contributing to the maturation of the pro-inflammatory interleukin-1β (IL-1β). − Hence, for the successful management of IBDs, it is imperative to meticulously design a biomaterial that can fully eradicate PAMPs, control mitochondrial dynamics, and scavenge mtROS, thus aiding the re-establishment of mitochondrial homeostasis and the easing of inflammatory reactions.…”