NEAT1 regulates microglial NLRP3 inflammasome activation

Among all inflammasomes, NLRP3 inflammasome is the most studied inflammasome complex. NLRP3 inflammasome is activated by diverse pathogen-related and danger-related molecular cues, associating NLRP3 inflammasome with various diseases, including autoimmune, metabolic, neurological, and psychiatric diseases. Upon assembly of the inflammasome complex, the caspase-1 is activated and cleaves pro-inflammatory cytokines, IL-1β and IL-18, along with GSDMD, a pore-forming membrane protein causing pyroptotic cell death. The activity of NLRP3 inflammasome activation must be regulated to prevent aberrant activity. These regulations occur at many levels, and long noncoding RNAs (lncRNAs) are one of the regulatory molecules on inflammasome activation in both priming and activation steps. lncRNA NEAT 1 and RNA-binding proteins NONO and SFPQ form a protein complex called paraspeckle, which regulates gene expression inhibiting translocation of mRNAs and miRNAs into the cytoplasm. The study aims to find the regulatory role of lncRNA NEAT1 on microglial NLRP3 inflammasome activation.Materials and methods: In our study, the NLRP3 inflammasome is primed by LPS (4h, 1µg/ml) and activated by ATP (5 mM) in N9 microglia. First, the change in lncRNA NEAT1 expression and paraspeckle formation was examined by RT-qPCR, western blotting, RIP assay, and FISH. After these experiments, the regulatory effect of NEAT1 on NLRP3 inflammasome activation was tested using NEAT1 siRNA. The changes in inflammasome markers were investigated by ELISA, RT-qPCR, western blotting, and Caspase-1 activity assay.&nbsp;Results: Here, we demonstrated that the expression of lncRNA NEAT1 is increased in LPS and ATP-induced microglial NLRP3 inflammasome activation. Although the expression of RNA-binding proteins NONO and SFPQ was not changed, the localization of these proteins was changed upon NLRP3 inflammasome activation. Furthermore, knocking down NEAT1 using siRNA revealed that NEAT1 regulated the cleavage of pro-inflammatory cytokine IL-1β via caspase-1 activity.&nbsp;&nbsp;&nbsp;&nbsp;Conclusion: Our findings suggest that lncRNA NEAT1 plays a role in the regulation of microglial NLRP3 inflammasome activation. Thus, the genetic or pharmacological manipulation of NEAT1 may contribute to the development of LncRNA-targeted innovative therapeutic strategies for the various neurodegenerative and neuropsychiatric diseases in which NLRP3 inflammasome activation participates in the pathogenesis.Key words: NLRP3 inflammasome, NEAT1, Microglia, lncRNA, miR-124</p