title: Dysregulated RNA-Induced Silencing Complex (RISC) Assembly within CNS Corresponds with Abnormal miRNA Expression during Autoimmune Demyelination.
abstract: MicroRNAs (miRNAs) associate with Argonaute (Ago), GW182, and FXR1 proteins to form RNA-induced silencing complexes (RISCs). RISCs represent a critical checkpoint in the regulation and bioavailability of miRNAs. Recent studies have revealed dysregulation of miRNAs in multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE); however, the function of RISCs in EAE and MS is largely unknown. Here, we examined the expression of Ago, GW182, and FXR1 in CNS tissue, oligodendrocytes (OLs), brain-infiltrating T lymphocytes, and CD3(+)splenocytes (SCs) of EAE mic, and found that global RISC protein levels were significantly dysregulated. Specifically, Ago2 and FXR1 levels were decreased in OLs and brain-infiltrating T cells in EAE mice. Accordingly, assembly of Ago2/GW182/FXR1 complexes in EAE brain tissues was disrupted, as confirmed by immunoprecipitation experiments. In parallel with alterations in RISC complex content in OLs, we found downregulation of miRNAs essential for differentiation and survival of OLs and myelin synthesis. In brain-infiltrating T lymphocytes, aberrant RISC formation contributed to miRNA-dependent proinflammatory helper T-cell polarization. In CD3(+) SCs, we found increased expression of both Ago2 and FXR1 in EAE compared with nonimmunized mice. Therefore, our results demonstrate a gradient in expression of miRNA between primary activated T cells in the periphery and polarized CNS-infiltrating T cells. These results suggest that, in polarized autoreactive effector T cells, miRNA synthesis is inhibited in response to dysregulated RISC assembly, allowing these cells to maintain a highly specific proinflammatory program. Therefore, our findings may provide a mechanism that leads to miRNA dysregulation in EAE/MS.
authors.affiliation: Department of Neurology, Laboratory of Neuroimmunology, Medical University of Lodz, 92-213 Lodz, Poland.
authors.forename: Przemysław
authors.initials: P
authors.lastname: Lewkowicz
authors.affiliation: Department of Neurology, Laboratory of Neuroimmunology, Medical University of Lodz, 92-213 Lodz, Poland.
authors.forename: Hanna
authors.initials: H
authors.lastname: Cwiklińska
authors.affiliation: Department of Neurology, Laboratory of Neuroimmunology, Medical University of Lodz, 92-213 Lodz, Poland.
authors.forename: Marcin P
authors.initials: MP
authors.lastname: Mycko
authors.affiliation: Department of Neurology, Laboratory of Neuroimmunology, Medical University of Lodz, 92-213 Lodz, Poland.
authors.forename: Maria
authors.initials: M
authors.lastname: Cichalewska
authors.affiliation: Department of Neurology, Laboratory of Neuroimmunology, Medical University of Lodz, 92-213 Lodz, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Domowicz
authors.affiliation: Department of Neurology, Laboratory of Neuroimmunology, Medical University of Lodz, 92-213 Lodz, Poland.
authors.forename: Natalia
authors.initials: N
authors.lastname: Lewkowicz
authors.affiliation: Department of Neurology, Laboratory of Neuroimmunology, Medical University of Lodz, 92-213 Lodz, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Jurewicz
authors.affiliation: Department of Neurology, Laboratory of Neuroimmunology, Medical University of Lodz, 92-213 Lodz, Poland kselmaj@afazja.am.lodz.pl.
authors.forename: Krzysztof W
authors.initials: KW
authors.lastname: Selmaj
mesh_terms: D000818:Animals; D060565:Argonaute Proteins / Q000378:metabolism; D001324:Autoantigens / Q000378:metabolism; D039481:CD11b Antigen / Q000378:metabolism; D002268:Carboxypeptidases / Q000378:metabolism*; D002490:Central Nervous System / Q000378:metabolism* / Q000473:pathology; D004195:Disease Models, Animal; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000276:immunology* / Q000473:pathology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D017493:Leukocyte Common Antigens / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000378:metabolism*; D063308:Myelin-Oligodendrocyte Glycoprotein / Q000633:toxicity; D009474:Neurons / Q000378:metabolism; D010446:Peptide Fragments / Q000633:toxicity; D012342:RNA, Small Nuclear / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism
chemical_list: C582332:Ago2 protein, rat; D060565:Argonaute Proteins; D001324:Autoantigens; D039481:CD11b Antigen; C496283:Fxr1h protein, mouse; D005904:Glial Fibrillary Acidic Protein; D035683:MicroRNAs; D063308:Myelin-Oligodendrocyte Glycoprotein; D010446:Peptide Fragments; D012342:RNA, Small Nuclear; D016601:RNA-Binding Proteins; D016693:Receptors, Antigen, T-Cell, alpha-beta; C465663:TNRC6A protein, human; C445081:myelin oligodendrocyte glycoprotein (35-55); D017493:Leukocyte Common Antigens; D002268:Carboxypeptidases; C486671:Scpep1 protein, mouse
keywords: Ago proteins; EAE; RISC; miRNA