Exposure to particulate crystals can induce oxidative stress in phagocytes, which triggers NLRP3 inflammasome-mediated interleukin-1β secretion to initiate undesirable inflammatory responses that are associated with both autoinflammatory and metabolic diseases. Although mitochondrial reactive oxygen species have a central role in NLRP3 inflammasome activation, how reactive oxygen species signal assembly of the NLRP3 inflammasome remains elusive. Here, we identify liposomes as novel activators of the NLRP3 inflammasome and further demonstrate that liposome-induced inflammasome activation also requires mitochondrial reactive oxygen species. Moreover, we find that stimulation with liposomes/crystals induced reactive oxygen species-dependent calcium influx via the TRPM2 channel and that macrophages deficient in TRPM2 display drastically impaired NLRP3 inflammasome activation and interleukin-1β secretion. Consistently, Trpm2^−/− mice are resistant to crystal-/liposome-induced interleukin-1β-mediated peritonitis in vivo. Together, these results identify TRPM2 as a key factor that links oxidative stress to the NLRP3 inflammasome activation. Therefore, targeting TRPM2 may be effective for the treatment of NLRP3 inflammasome-associated inflammatory disorders.

Duchenne muscular dystrophy (DMD) is a degenerative muscle disease caused by genetic mutations that lead to the disruption of dystrophin in muscle fibers. There is no curative treatment for this devastating disease. Clustered regularly interspaced short palindromic repeat/Cas9 (CRISPR/Cas9) has emerged as a powerful tool for genetic manipulation and potential therapy. Here we demonstrate that CRIPSR-mediated genome editing efficiently excised a 23-kb genomic region on the X-chromosome covering the mutant exon 23 in a mouse model of DMD, and restored dystrophin expression and the dystrophin-glycoprotein complex at the sarcolemma of skeletal muscles in live mdx mice. Electroporation-mediated transfection of the Cas9/gRNA constructs in the skeletal muscles of mdx mice normalized the calcium sparks in response to osmotic shock. Adenovirus-mediated transduction of Cas9/gRNA greatly reduced the Evans blue dye uptake of skeletal muscles at rest and after downhill treadmill running. This study provides proof evidence for permanent gene correction in DMD.

Skeletal muscle basal lamina is linked to the sarcolemma through transmembrane receptors, including integrins and dystroglycan. The function of dystroglycan relies critically on posttranslational glycosylation, a common target shared by a genetically heterogeneous group of muscular dystrophies characterized by α-dystroglycan hypoglycosylation. Here we show that both dystroglycan and integrin α7 contribute to force-production of muscles, but that only disruption of dystroglycan causes detachment of the basal lamina from the sarcolemma and renders muscle prone to contraction-induced injury. These phenotypes of dystroglycan-null muscles are recapitulated by Large ^myd muscles, which have an intact dystrophin–glycoprotein complex and lack only the laminin globular domain-binding motif on α-dystroglycan. Compromised sarcolemmal integrity is directly shown in Large ^myd muscles and similarly in normal muscles when arenaviruses compete with matrix proteins for binding α-dystroglycan. These data provide direct mechanistic insight into how the dystroglycan-linked basal lamina contributes to the maintenance of sarcolemmal integrity and protects muscles from damage.

Dilated cardiomyopathy is a life-threatening syndrome that can arise from a myriad of causes, but predisposition toward this malady is inherited in many cases. A number of inherited forms of dilated cardiomyopathy arise from mutations in genes that encode proteins involved in linking the cytoskeleton to the extracellular matrix, and disruption of this link renders the cell membrane more susceptible to injury. Membrane repair is an important cellular mechanism that animal cells have developed to survive membrane disruption. We have previously shown that dysferlin deficiency leads to defective membrane resealing in skeletal muscle and muscle necrosis; however, the function of dysferlin in the heart remains to be determined. Here, we demonstrate that dysferlin is also involved in cardiomyocyte membrane repair and that dysferlin deficiency leads to cardiomyopathy. In particular, stress exercise disturbs left ventricular function in dysferlin-null mice and increases Evans blue dye uptake in dysferlin-deficient cardiomyocytes. Furthermore, a combined deficiency of dystrophin and dysferlin leads to early onset cardiomyopathy. Our results suggest that dysferlin-mediated membrane repair is important for maintaining membrane integrity of cardiomyocytes, particularly under conditions of mechanical stress. Thus, our study establishes what we believe is a novel mechanism underlying the cardiomyopathy that results from a defective membrane repair in the absence of dysferlin.