Dataset Information

Crohn's disease IRGM risk alleles are associated with altered gene expression in human tissues.

ABSTRACT: Crohn's disease (CD) is a chronic inflammatory gastrointestinal disorder. Genetic association studies have implicated dysregulated autophagy in CD. Among risk loci identified are a promoter single nucleotide polymorphism (SNP)( rs13361189 ) and two intragenic SNPs ( rs9637876 , rs10065172 ) in immunity-related GTPase family M ( IRGM) a gene that encodes a protein of the autophagy initiation complex. All three SNPs have been proposed to modify IRGM expression, but reports have been divergent and largely derived from cell lines. Here, analyzing RNA-Sequencing data of human tissues from the Genotype-Tissue Expression Project, we found that rs13361189 minor allele carriers had reduced IRGM expression in whole blood and terminal ileum, and upregulation in ileum of ZNF300P1, a locus adjacent to IRGM on chromosome 5q33.1 that encodes a long noncoding RNA. Whole blood and ileum from minor allele carriers had altered expression of multiple additional genes that have previously been linked to colitis and/or autophagy. Notable among these was an increase in ileum of LTF (lactoferrin), an established fecal inflammatory biomarker of CD, and in whole blood of TNF, a key cytokine in CD pathogenesis. Last, we confirmed that risk alleles at all three loci associated with increased risk for CD but not ulcerative colitis in a case-control study. Taken together, our findings suggest that genetically encoded IRGM deficiency may predispose to CD through dysregulation of inflammatory gene networks. Gene expression profiling of disease target tissues in genetically susceptible populations is a promising strategy for revealing new leads for the study of molecular pathogenesis and, potentially, for precision medicine. NEW & NOTEWORTHY Single nucleotide polymorphisms in immunity-related GTPase family M ( IRGM), a gene that encodes an autophagy initiation protein, have been linked epidemiologically to increased risk for Crohn's disease (CD). Here, we show for the first time that subjects with risk alleles at two such loci, rs13361189 and rs10065172 , have reduced IRGM expression in whole blood and terminal ileum, as well as dysregulated expression of a wide array of additional genes that regulate inflammation and autophagy.

SUBMITTER: Ajayi TA

PROVIDER: S-EPMC6383377 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Crohn's disease IRGM risk alleles are associated with altered gene expression in human tissues.

Ajayi Teminioluwa A TA Innes Cynthia L CL Grimm Sara A SA Rai Prashant P Finethy Ryan R Coers Jörn J Wang Xuting X Bell Douglas A DA McGrath John A JA Schurman Shepherd H SH Fessler Michael B MB

American journal of physiology. Gastrointestinal and liver physiology 20181018 1

Crohn's disease (CD) is a chronic inflammatory gastrointestinal disorder. Genetic association studies have implicated dysregulated autophagy in CD. Among risk loci identified are a promoter single nucleotide polymorphism (SNP)( rs13361189 ) and two intragenic SNPs ( rs9637876 , rs10065172 ) in immunity-related GTPase family M ( IRGM) a gene that encodes a protein of the autophagy initiation complex. All three SNPs have been proposed to modify IRGM expression, but reports have been divergent and ...[more]

PMID: 30335469

Similar Datasets

Project description:Genome-wide association studies have identified a coronary artery disease (CAD) risk locus in a non-coding region at 9p21.3, the nearest genes being CDKN2A and CDKN2B. To understand the pathways by which this locus might influence CAD susceptibility, we investigated associations between the 9p21.3 risk genotype and global gene expression in heart tissue from donors with no diagnosed heart disease (n?=?108, predominant cause of death, cerebral vascular accident) and in carotid plaque (n?=?106), aorta (n?=?104) and mammary artery (n?=?88) tissues from heart valve and carotid endarterectomy patients. Genotyping was performed with Taqman assays and Illumina arrays, and gene expression profiles generated with Affymetrix microarrays. Associations were analyzed with an additive genetic model. In heart tissue, 46 genes were putatively altered in association with the 9p21.3 risk allele (70% down-regulated, fold-change >1.1 per allele, p<0.05 adjusted for age, gender, ethnicity, cause of death). These genes were enriched for biomarkers of myocardial infarction (p?=?1.53×10(-9)), response to wounding (p?=?2.65×10(-10)) and inflammatory processes (p<1.97×10(-7)). Among the top 10 most down-regulated genes, 7 genes shared a set of transcription factor binding sites within conserved promoter regions (p<1.14×10(-5)), suggesting they may be co-regulated. Canonical pathway modelling of the most differentially expressed transcripts across all tissues (154 genes, 60% down-regulated, fold-change >1.1 per allele, p<0.01) showed that 75% of the genes could be transcriptionally regulated through the cell cycle G1 phase progression pathway (p<1.08×10(-258)), in which CDKN2A and CDKN2B play a regulatory role. These data suggest that the cell cycle G1 phase progression pathway is activated in individuals with the 9p21.3 risk allele. This may contribute to a proliferative phenotype that promotes adverse cardiac hypertrophy and vascular remodeling, leading to an increased CAD risk.

Project description:The aim of the present meta-analysis was to evaluate the correlation between a common polymorphism, rs13361189 C>T in the immunity-related GTPase M (IRGM) gene, and susceptibility to Crohn's disease (CD). The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library and CBM databases were investigated from database inception through to October 1, 2013 without the application of any language restrictions. The meta-analysis was performed using STATA 12.0 software and the relative risk (RR) with a 95% confidence interval (CI) was calculated. Seven case-control studies were included with a total of 3,093 CD patients and 3,227 healthy control subjects. The results of the meta-analysis revealed that the IRGM rs13361189 polymorphism correlates with an increased risk of CD (T allele versus C allele: RR=1.25 with 95% CI, 1.04-1.50; P=0.016 and CT + TT versus CC: RR=1.21 with 95% CI, 1.03-1.42; P=0.018). A subgroup analysis conducted using a genotyping method indicated that the IRGM rs13361189 polymorphism was correlated with an increased risk of CD in the TaqMan® (T allele versus C allele: RR=1.32 with 95% CI, 1.01-1.73; P=0.042) and the polymerase chain reaction-restriction fragment length polymorphism subgroups (T allele versus C allele: RR=1.80 with 95% CI, 1.32-2.45; P<0.001 and CT + TT versus CC: RR=1.61 with 95% CI, 1.19-2.18; P=0.018). However, no correlation was observed in the direct sequencing subgroup (P>0.05). Further subgroup analysis by sample size demonstrated significant correlations between the IRGM rs13361189 polymorphism and an increased risk of CD in the large sample-size subgroup (T allele versus C allele: RR=1.46 with 95% CI, 1.26-1.68; P<0.001 and CT + TT versus CC: RR=1.40 with 95% CI, 1.21-1.62; P<0.001). However, no correlation was identified between the IRGM rs13361189 polymorphism and CD risk in the small sample-size subgroup (P>0.05). The present meta-analysis indicated that the IRGM rs13361189 polymorphism may contribute to susceptibility to CD. Thus, IRGM rs13361189 polymorphism may be a potential biomarker for the early diagnosis of CD.

Project description:This UH2/UH3 demonstration project entitled "Effects of Crohn's disease risk alleles on enteric microbiota" is focused on characterizing intestinal associated microbiota in patients with ileal Crohn's disease (ileal CD), ulcerative colitis (UC) and control patients without inflammatory bowel diseases (non-IBD). We hypothesize that genetic factors that affect Paneth cell function, contribute to compositional changes in intestinal microbiota. These changes in microbiota may lead to reduction of protective commensal organisms and increased numbers of aggressive organisms that incite intestinal inflammation. This hypothesis is being tested by high throughput 16S rRNA sequence analysis of de-identified ileal and colonic tissues that have been archived at Washington University St. Louis, University of North Carolina, Mount Sinai Hospital and the Cleveland Clinic. Multivariate analysis of the metagenomic data will be conducted with genotyping metadata (highly reproducible CD risk alleles, including NOD2 and ATG16L1) and phenotyping metadata (e.g. age, gender, race, body mass index, medications and smoking.) Shotgun sequencing will be performed on selected fecal specimens linked to ileal tissues to identify additional, or auxiliary, or synergistic pathogenic factors or other functional changes in the microbiome. Because members of this research team have observed that a chronic viral infection is required for the Paneth cell defect in Atg16l1 hypomorphic mice, a major focus of these studies will be towards identifying potential viral triggers for the defective Paneth cell phenotype in individuals harboring the ATG16L1 risk allele. Novel genetic probes for protective and aggressive organisms will be developed by mining bacterial genome and shotgun sequencing data. Genomic sequences will be produced for candidate protective and aggressive strains (e.g. adherent-invasive strains of E. coli) isolated from human intestinal tissues where there is limited existing genome information. Quantitative qPCR assays using the novel as well as established genetic probes will be conducted to test the hypothesis that an imbalance between protective and aggressive organisms is associated with genetic factors that affect Paneth cell function. Our combined expertise in multiple disciplines across multiple institutions, our demonstrated ability to collect a large number of well-phenotyped samples with longitudinal clinical information that will be linked to host response and morphologic studies, and our consortium's capacity for high-throughput sequencing will be used to investigate how alterations in human microbiome relate to CD risk alleles and CD pathogenesis.

Dataset Information

Crohn's disease IRGM risk alleles are associated with altered gene expression in human tissues.

Publications

Crohn's disease IRGM risk alleles are associated with altered gene expression in human tissues.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets