title: Expression of the Ian family of putative GTPases during T cell development and description of an Ian with three sets of GTP/GDP-binding motifs.
abstract: Reports suggest that two members of the novel immune-associated nucleotide (Ian) GTPase family, Ian1 and Ian5, play roles in T cell development. We performed real-time PCR analysis of the expression of Ian genes of the rat during T cell maturation, in macrophages and in cell lines. We found that all of the genes were expressed at relatively low levels at the early double-negative thymocyte stage but were expressed more strongly at later cell stages. Our study also revealed the fact that the previously reported Ian9, Ian10 and Ian11 genes are, instead, parts of a single gene for which we retain the name Ian9, potentially encoding a GTPase with a highly unusual triplicated structure. Antisera were developed against both Ian1 and Ian9. We established that Ian9 is produced as an approximately 75-kDa protein in both T cells and thymocytes. We observed that levels of both Ian1 and Ian9 proteins are profoundly reduced in T cells from lymphopenic rats as compared with wild-type rats. It was demonstrated that thymocytes and B cells from lymphopenic rats (Ian5 null) did not show enhanced sensitivity to gamma-irradiation-induced apoptosis.
authors.affiliation: Babraham Institute, Cambridge CB2 4AT, UK.
authors.forename: Carine
authors.initials: C
authors.lastname: Dion
authors.forename: Christine
authors.initials: C
authors.lastname: Carter
authors.forename: Lucy
authors.initials: L
authors.lastname: Hepburn
authors.forename: W John
authors.initials: WJ
authors.lastname: Coadwell
authors.forename: Geoff
authors.initials: G
authors.lastname: Morgan
authors.forename: Margaret
authors.initials: M
authors.lastname: Graham
authors.forename: Nicholas
authors.initials: N
authors.lastname: Pugh
authors.forename: Graham
authors.initials: G
authors.lastname: Anderson
authors.forename: Geoffrey W
authors.initials: GW
authors.lastname: Butcher
authors.forename: J Ross
authors.initials: JR
authors.lastname: Miller
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002454:Cell Differentiation / Q000276:immunology*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000276:immunology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000276:immunology*; D006801:Humans; D008231:Lymphopenia / Q000235:genetics / Q000276:immunology; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics / Q000276:immunology*; D051381:Rats; D011922:Rats, Mutant Strains; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D019204:GTP-Binding Proteins; C494977:Gimap5 protein, rat