title: Aire knockdown in medullary thymic epithelial cells affects Aire protein, deregulates cell adhesion genes and decreases thymocyte interaction.
abstract: We demonstrate that even a partial reduction of Aire mRNA levels by siRNA-induced Aire knockdown (Aire KD) has important consequences to medullary thymic epithelial cells (mTECs). Aire knockdown is sufficient to reduce Aire protein levels, impair its nuclear location, and cause an imbalance in large-scale gene expression, including genes that encode cell adhesion molecules. These genes drew our attention because adhesion molecules are implicated in the process of mTEC-thymocyte adhesion, which is critical for T cell development and the establishment of central self-tolerance. Accordingly, we consider the following: 1) mTECs contribute to the elimination of self-reactive thymocytes through adhesion; 2) Adhesion molecules play a crucial role during physical contact between these cells; and 3) Aire is an important transcriptional regulator in mTECs. However, its role in controlling mTEC-thymocyte adhesion remains unclear. Because Aire controls adhesion molecule genes, we hypothesized that the disruption of its expression could influence mTEC-thymocyte interaction. To test this hypothesis, we used a murine Aire(+) mTEC cell line as a model system to reproduce mTEC-thymocyte adhesion in vitro. Transcriptome analysis of the mTEC cell line revealed that Aire KD led to the down-modulation of more than 800 genes, including those encoding for proteins involved in cell adhesion, i.e., the extracellular matrix constituent Lama1, the CAM family adhesion molecules Vcam1 and Icam4, and those that encode peripheral tissue antigens. Thymocytes co-cultured with Aire KD mTECs had a significantly reduced capacity to adhere to these cells. This finding is the first direct evidence that Aire also plays a role in controlling mTEC-thymocyte adhesion.
authors: Molecular Immunogenetics Group, Department of Genetics, Ribeirão Preto Medical School, University of São Paulo (USP), Ribeirão Preto, SP, Brazil.
authors: Nicole
authors: N
authors: Pezzi
authors: Molecular Immunogenetics Group, Department of Genetics, Ribeirão Preto Medical School, University of São Paulo (USP), Ribeirão Preto, SP, Brazil.
authors: Amanda Freire
authors: AF
authors: Assis
authors: Molecular Immunogenetics Group, Department of Genetics, Ribeirão Preto Medical School, University of São Paulo (USP), Ribeirão Preto, SP, Brazil.
authors: Larissa Cotrim
authors: LC
authors: Cotrim-Sousa
authors: Department of Cellular and Molecular Biology, Ribeirão Preto Medical School, USP, Ribeirão Preto, SP, Brazil.
authors: Gabriel Sarti
authors: GS
authors: Lopes
authors: Molecular Immunogenetics Group, Department of Genetics, Ribeirão Preto Medical School, University of São Paulo (USP), Ribeirão Preto, SP, Brazil.
authors: Maritza Salas
authors: MS
authors: Mosella
authors: Department of Cellular and Molecular Biology, Ribeirão Preto Medical School, USP, Ribeirão Preto, SP, Brazil.
authors: Djalma Sousa
authors: DS
authors: Lima
authors: Department of Morphology, Physiology and Basic Pathology, School of Dentistry of Ribeirão Preto, USP, Ribeirão Preto, SP, Brazil.
authors: Karina F
authors: KF
authors: Bombonato-Prado
authors: Molecular Immunogenetics Group, Department of Genetics, Ribeirão Preto Medical School, University of São Paulo (USP), Ribeirão Preto, SP, Brazil; Department of Morphology, Physiology and Basic Pathology, School of Dentistry of Ribeirão Preto, USP, Ribeirão Preto, SP, Brazil. Electronic address: passos@usp.br.
authors: Geraldo Aleixo
authors: GA
authors: Passos
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002448:Cell Adhesion / Q000276:immunology*; D002454:Cell Differentiation / Q000276:immunology; D004847:Epithelial Cells / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000276:immunology; D055785:Gene Knockdown Techniques; D017404:In Situ Hybridization, Fluorescence; D051379:Mice; D008810:Mice, Inbred C57BL; D016133:Polymerase Chain Reaction; D017634:Self Tolerance / Q000276:immunology; D060168:Thymocytes / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D014157:Transcription Factors / Q000276:immunology / Q000378:metabolism*; D059467:Transcriptome / Q000276:immunology; D000096927:AIRE Protein
chemical_list: D014157:Transcription Factors; D000096927:AIRE Protein
keywords: Aire gene; Thymocyte; Thymus; mTEC; mTEC-thymocyte adhesion; siRNA