title: MicroRNA-133a-1 regulates inflammasome activation through uncoupling protein-2.
abstract: Inflammasomes are multimeric protein complexes involved in the processing of IL-1β through Caspase-1 cleavage. NLRP3 is the most widely studied inflammasome, which has been shown to respond to a large number of both endogenous and exogenous stimuli. Although studies have begun to define basic pathways for the activation of inflammasome and have been instrumental in identifying therapeutics for inflammasome related disorders; understanding the inflammasome activation at the molecular level is still incomplete. Recent functional studies indicate that microRNAs (miRs) regulate molecular pathways and can lead to diseased states when hampered or overexpressed. Mechanisms involving the miRNA regulatory network in the activation of inflammasome and IL-1β processing is yet unknown. This report investigates the involvement of miR-133a-1 in the activation of inflammasome (NLRP3) and IL-1β production. miR-133a-1 is known to target the mitochondrial uncoupling protein 2 (UCP2). The role of UCP2 in inflammasome activation has remained elusive. To understand the role of miR-133a-1 in regulating inflammasome activation, we either overexpressed or suppressed miR-133a-1 in differentiated THP1 cells that express the NLRP3 inflammasome. Levels of Caspase-1 and IL-1β were analyzed by Western blot analysis. For the first time, we showed that overexpression of miR-133a-1 increases Caspase-1 p10 and IL-1β p17 cleavage, concurrently suppressing mitochondrial uncoupling protein 2 (UCP2). Surprisingly, our results demonstrated that miR-133A-1 controls inflammasome activation without affecting the basal expression of the individual inflammasome components NLRP3 and ASC or its immediate downstream targets proIL-1β and pro-Caspase-1. To confirm the involvement of UCP2 in the regulation of inflammasome activation, Caspase-1 p10 and IL-1β p17 cleavage in UCP2 of overexpressed and silenced THP1 cells were studied. Suppression of UCP2 by siRNA enhanced the inflammasome activity stimulated by H2O2 and, conversely, overexpression of UCP2 decreased the inflammasome activation. Collectively, these studies suggest that miR-133a-1 suppresses inflammasome activation via the suppression of UCP2.
authors.affiliation: Division of Allergy and Immunology, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., Tampa, FL 33612, USA.
authors.forename: Sayantani
authors.initials: S
authors.lastname: Bandyopadhyay
authors.forename: Troy
authors.initials: T
authors.lastname: Lane
authors.forename: Rajanbabu
authors.initials: R
authors.lastname: Venugopal
authors.forename: Prasanna Tamarapu
authors.initials: PT
authors.lastname: Parthasarathy
authors.forename: Young
authors.initials: Y
authors.lastname: Cho
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Galam
authors.forename: Richard
authors.initials: R
authors.lastname: Lockey
authors.forename: Narasaiah
authors.initials: N
authors.lastname: Kolliputi
mesh_terms: D000818:Animals; D051017:Apoptosis Regulatory Proteins; D053468:CARD Signaling Adaptor Proteins; D002352:Carrier Proteins / Q000235:genetics; D020170:Caspase 1 / Q000276:immunology; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D003598:Cytoskeletal Proteins / Q000235:genetics; D015536:Down-Regulation; D020868:Gene Silencing; D006801:Humans; D058847:Inflammasomes / Q000276:immunology*; D053583:Interleukin-1beta / Q000276:immunology*; D007473:Ion Channels / Q000235:genetics / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D035683:MicroRNAs / Q000276:immunology*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000276:immunology*; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D000071246:Uncoupling Protein 2; D015854:Up-Regulation
chemical_list: D051017:Apoptosis Regulatory Proteins; D053468:CARD Signaling Adaptor Proteins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D058847:Inflammasomes; D053583:Interleukin-1beta; D007473:Ion Channels; C548234:MIRN133 microRNA, human; D035683:MicroRNAs; D024101:Mitochondrial Proteins; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C492716:Nlrp3 protein, mouse; C498534:Pycard protein, mouse; C000604389:UCP2 protein, human; C000604390:Ucp2 protein, mouse; D000071246:Uncoupling Protein 2; D020170:Caspase 1
keywords: IL-1β; Inflammasome; Inflammation; Mitochondria; ROS; THP1; UCP2; human monocyte cell line; interleukin 1 beta; miR; micro RNA; microRNA; siRNA; silencing RNA; uncoupling protein 2