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Association of IRF5 in UK SLE families identifies a variant involved in polyadenylation.

ABSTRACT: Results from two studies have implicated the interferon regulatory gene IRF5 as a susceptibility gene in systemic lupus erythematosus (SLE). In this study, we conducted a family-based association analysis in 380 UK SLE nuclear families. Using a higher density of markers than has hitherto been screened, we show that there is association with two SNPs in the first intron, rs2004640 (P = 3.4 x 10(-4)) and rs3807306 (P = 4.9 x 10(-4)), and the association extends into the 3'-untranslated region (UTR). There is a single haplotype block encompassing IRF5 and we show for the first time that the gene comprises two over-transmitted haplotypes and a single under-transmitted haplotype. The strongest association is with a TCTAACT haplotype (T:U = 1.92, P = 5.8 x 10(-5)), which carries all the over-transmitted alleles from this study. Haplotypes carrying the T alleles of rs2004640 and rs2280714 and the A allele of rs10954213 are over-transmitted in SLE families. The TAT haplotype shows a dose-dependent relationship with mRNA expression. A differential expression pattern was seen between two expression probes located each side of rs10954213 in the 3'-UTR. rs10954213 shows the strongest association with RNA expression levels (P = 1 x 10(-14)). The A allele of rs10954213 creates a functional polyadenylation site and the A genotype correlates with increased expression of a transcript variant containing a shorter 3'-UTR. Expression levels of transcript variants with the shorter or longer 3'-UTRs are inversely correlated. Our data support a new mechanism by which an IRF5 polymorphism controls the expression of alternate transcript variants which may have different effects on interferon signalling.

SUBMITTER: Cunninghame Graham DS

PROVIDER: S-EPMC3706933 | biostudies-literature | 2007 Mar

REPOSITORIES: biostudies-literature

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Association of IRF5 in UK SLE families identifies a variant involved in polyadenylation.

Cunninghame Graham Deborah S DS Manku Harinder H Wagner Susanne S Reid Julia J Timms Kirsten K Gutin Alexander A Lanchbury Jerry S JS Vyse Tim J TJ

Human molecular genetics 20061222 6

Results from two studies have implicated the interferon regulatory gene IRF5 as a susceptibility gene in systemic lupus erythematosus (SLE). In this study, we conducted a family-based association analysis in 380 UK SLE nuclear families. Using a higher density of markers than has hitherto been screened, we show that there is association with two SNPs in the first intron, rs2004640 (P = 3.4 x 10(-4)) and rs3807306 (P = 4.9 x 10(-4)), and the association extends into the 3'-untranslated region (UTR ...[more]

PMID: 17189288

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Project description:Polymorphisms in the interferon regulatory factor 5 (IRF5) gene have been consistently replicated and shown to confer risk for or protection from the development of systemic lupus erythematosus (SLE). IRF5 expression is significantly upregulated in SLE patients and upregulation associates with IRF5-SLE risk haplotypes. IRF5 alternative splicing has also been shown to be elevated in SLE patients. Given that human IRF5 exists as multiple alternatively spliced transcripts with distinct function(s), it is important to determine whether the IRF5 transcript profile expressed in healthy donor immune cells is different from that expressed in SLE patients. Moreover, it is not currently known whether an IRF5-SLE risk haplotype defines the profile of IRF5 transcripts expressed. Using standard molecular cloning techniques, we identified and isolated 14 new differentially spliced IRF5 transcript variants from purified monocytes of healthy donors and SLE patients to generate an IRF5 variant transcriptome. Next-generation sequencing was then used to perform in-depth and quantitative analysis of full-length IRF5 transcript expression in primary immune cells of SLE patients and healthy donors by next-generation sequencing. Evidence for additional alternatively spliced transcripts was obtained from de novo junction discovery. Data from these studies support the overall complexity of IRF5 alternative splicing in SLE. Results from next-generation sequencing correlated with cloning and gave similar abundance rankings in SLE patients thus supporting the use of this new technology for in-depth single gene transcript profiling. Results from this study provide the first proof that 1) SLE patients express an IRF5 transcript signature that is distinct from healthy donors, 2) an IRF5-SLE risk haplotype defines the top four most abundant IRF5 transcripts expressed in SLE patients, and 3) an IRF5 transcript signature enables clustering of SLE patients with the H2 risk haplotype.

Project description:Understanding how genomes encode complex cellular and organismal behaviors is an outstanding challenge of modern genetics. Unlike classical screening methods, analysis of the genetic variation that occurs naturally in wild populations can enable rapid, genome-scale trait mapping with a medium-throughput experimental design. Here we describe the results of the first genome-wide association analysis (GWAS) of a microbial eukaryote, using wild isolates of the filamentous fungus Neurospora crassa. We transcriptionally profiled each of 112 individuals collected in Louisiana and used RNA-seq data to genotype each strain at thousands of genetic loci genome-wide. We used these genotypes in a mapping analysis of microbial communication. In N. crassa, germinated asexual spores (germlings) sense the presence of other germlings, grow toward them in a coordinated fashion, and fuse. We evaluated germlings of each strain for their ability to chemically sense, chemotropically seek, and undergo cell fusion. GWAS identified one gene, NCU04379 (cse-1, encoding a homolog of neuronal calcium sensor), at which inheritance was strongly associated with the efficiency of germling communication. Deletion of cse-1 significantly lowered germling communication and fusion, and two genes encoding predicted binding partners of CSE-1 were also required for the communication trait. Additionally, mining our association results for signaling and secretion genes with a potential role in germling communication, we validated six more novel determinants of germling communication, including a secreted protease and two other genes whose deletion conferred a novel phenotype of increased communication and multi-germling fusion. These results establish protein secretion as a linchpin of germling communication in N. crassa and shed light on the regulation of communication molecules in this fungus. Our study demonstrates the power of population-genetic analyses for the rapid identification of genes contributing to complex traits in microbial species. 112 mycelial mRNA profiles of 16 hour wild type (WT) Neurospora crassa strains were generated by deep sequencing, using Illumina GAIIx.

Dataset Information

Association of IRF5 in UK SLE families identifies a variant involved in polyadenylation.

Publications

Association of IRF5 in UK SLE families identifies a variant involved in polyadenylation.

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