The Novel Long Non-Coding RNA Nostrill Regulates Intestinal Epithelial Defense Against Cryptosporidium parvum and Modulates Microglial-Mediated Neurotoxicity

Abstract

Increasing evidence supports the role of long non-coding RNAs (lncRNAs) as critical regulators of diverse cellular processes, however, their role in antimicrobial host defense and inflammatory regulation is incompletely understood. In this study, we hypothesize that a novel lncRNA candidate broadly contributes to antimicrobial host defense and neuroinflammation through transcriptional regulation of target genes. Here we provide evidence that the lncRNA Nostrill is upregulated in the intestinal epithelium following infection by Cryptosporidium parvum, a globally prevalent protozoan parasite that causes significant diarrheal disease and an important opportunistic pathogen in the immunocompromised. Induction of Nostrill was triggered by NF-κB signaling and was observed to enhance epithelial defense by decreasing parasitic infection burden. Nostrill participates in the transcriptional regulation of C. parvum-induced Irf7 expression through interactions with NF-κB p65, and induction of Nostrill promotes activating epigenetic histone modifications and occupancy of RNA polymerase II at the Irf7 promoter. Two positionally conserved human orthologs of Nostrill were induced in response to C. parvum infection and similarly contribute to epithelial defense against C. parvum. Our data suggest that the induction of Nostrill promotes intestinal epithelial antiparasitic defense against C. parvum through contributions to transcriptional regulation of immune-related genes, such as Irf7, and may provide a novel therapeutic target to enhance treatment of cryptosporidiosis. LncRNAs may help direct proinflammatory responses of microglia, the resident immunocompetent and phagocytic cells in the central nervous system (CNS). Pro-inflammatory microglia are neurotoxic and contribute to the pathogenesis of several neurodegenerative diseases. Nostrill was induced by LPS stimulation in BV2 cells, primary murine microglia, and in cortical tissue of LPS-injected mice. Induction of Nostrill is NF-κB-dependent and promotes inducible nitric oxide synthase (iNOS) expression and downstream nitric oxide (NO) production. In vitro studies demonstrated that knockdown of Nostrill in microglia reduced LPS-stimulated microglial neurotoxicity. Investigation of the underlying molecular mechanism showed Nostrill interacts with NF-κB p65 and associates with the iNOS promoter region to enhance localization of NF-κB p65, RNA polymerase II, and activating histone modifications at the iNOS promoter. Nostrill may be an important target for reducing neurotoxicity associated with iNOS-mediated inflammatory processes in microglia during neurodegeneration.