title: Immune-associated nucleotide-1 (IAN-1) is a thymic selection marker and defines a novel gene family conserved in plants.
abstract: Positive selection of thymocytes is a complex and crucial event in T cell development that is characterized by cell death rescue, commitment toward the helper or cytotoxic lineage, and functional maturation of thymocytes bearing an appropriate TCR. To search for novel genes involved in this process, we compared gene expression patterns in positively selected thymocytes and their immediate progenitors in mice using the differential display technique. This approach lead to the identification of a novel gene, mIAN-1 (murine immune-associated nucleotide-1), that is switched on upon positive selection and predominantly expressed in the lymphoid system. We show that mIAN-1 encodes a 42-kDa protein sharing sequence homology with the pathogen-induced plant protein aig1 and that it defines a novel family of at least three putative GTP-binding proteins. Analysis of protein expression at various stages of thymocyte development links mIAN-1 to CD3-mediated selection events, suggesting that it represents a key player of thymocyte development and that it participates to peripheral specific immune responses. The evolutionary conservation of the IAN family provides a unique example of a plant pathogen response gene conserved in animals.
authors.affiliation: Anatomy Department, Medical School, Birmingham University, Edgbaston, United Kingdom. poirigmc@novell5.bham.ac.uk
authors.forename: G M
authors.initials: GM
authors.lastname: Poirier
authors.forename: G
authors.initials: G
authors.lastname: Anderson
authors.forename: A
authors.initials: A
authors.lastname: Huvar
authors.forename: P C
authors.initials: PC
authors.lastname: Wagaman
authors.forename: J
authors.initials: J
authors.lastname: Shuttleworth
authors.forename: E
authors.initials: E
authors.lastname: Jenkinson
authors.forename: M R
authors.initials: MR
authors.lastname: Jackson
authors.forename: P A
authors.initials: PA
authors.lastname: Peterson
authors.forename: M G
authors.initials: MG
authors.lastname: Erlander
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D001483:Base Sequence; D015415:Biomarkers / Q000737:chemistry; D017252:CD3 Complex / Q000502:physiology; D002454:Cell Differentiation / Q000276:immunology; D003001:Cloning, Molecular; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000737:chemistry / Q000302:isolation & purification; D019204:GTP-Binding Proteins / Q000737:chemistry* / Q000235:genetics*; D017343:Genes, Plant; D008214:Lymphocytes / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000276:immunology*; D009924:Organ Culture Techniques; D009928:Organ Specificity / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D013950:Thymus Gland / Q000737:chemistry / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; D015415:Biomarkers; D017252:CD3 Complex; D018076:DNA, Complementary; C400051:Ian1 protein, mouse; C485689:Ian3 protein, mouse; D010940:Plant Proteins; D012333:RNA, Messenger; D019204:GTP-Binding Proteins