Project description:The major histocompatibility complex (MHC) region represents by far the strongest multiple sclerosis (MS) susceptibility loci. DNA methylation changes have been consistently detected at the MHC region in MS. However, understanding the full picture of epigenetic regulations of MHC in MS remains challenging, due in part to the limited coverage in the region by standard whole genome bisulfite sequencing or array-based methods. To fill this gap, we utilized a novel but validated MHC capture protocol with bisulfite sequencing and conducted a comprehensive analysis of MHC methylation landscapes in blood samples from 147 treatment naïve MS participants and 129 healthy controls. We identified 132 differentially methylated region (DMRs) within MHC regions and found they are significantly overlapped with MS risk variants. Integration of the MHC methylome to human leukocyte antigen (HLA) genetic data further indicate that the methylation changes are significantly associated with HLA genotypes. Using DNA methylation quantitative trait loci (mQTL) mapping and the causal inference test (CIT), we identified 643 cis-mQTL-DMRs paired associations including 71 DMRs possibly mediating causal relationships between 55 SNPs and MS risk.
Project description:Characterisation of the kinetics of abacavir-induced perturbation of the immunopeptidome of the Major Histocompatibility Complex (MHC) class I molecule HLA-B*57:01.
Project description:To dissect the requirements of membrane protein degradation from the ER, we expressed the mouse major histocompatibility complex class I heavy chain H-2K(b) in yeast. Like other proteins degraded from the ER, unassembled H-2K(b) heavy chains are not transported to the Golgi but are degraded in a proteasome-dependent manner. The overexpression of H-2K(b) heavy chains induces the unfolded protein response (UPR). In yeast mutants unable to mount the UPR, H-2K(b) heavy chains are greatly stabilized. This defect in degradation is suppressed by the expression of the active form of Hac1p, the transcription factor that upregulates UPR-induced genes. These results indicate that induction of the UPR is required for the degradation of protein substrates from the ER.
Project description:ObjectiveVariation in the major histocompatibility complex (MHC) on chromosome 6p21 is known to influence susceptibility to multiple sclerosis with the strongest effect originating from the HLA-DRB1 gene in the class II region. The possibility that other genes in the MHC independently influence susceptibility to multiple sclerosis has been suggested but remains unconfirmed.MethodsUsing a combination of microsatellite, single nucleotide polymorphism, and human leukocyte antigen (HLA) typing, we screened the MHC in trio families looking for evidence of residual association above and beyond that attributable to the established DRB1*1501 risk haplotype. We then refined this analysis by extending the genotyping of classical HLA loci into independent cases and control subjects.ResultsScreening confirmed the presence of residual association and suggested that this was maximal in the region of the HLA-C gene. Extending analysis of the classical loci confirmed that this residual association is partly due to allelic heterogeneity at the HLA-DRB1 locus, but also reflects an independent effect from the HLA-C gene. Specifically, the HLA-C*05 allele, or a variant in tight linkage disequilibrium with it, appears to exert a protective effect (p = 3.3 x 10(-5)).InterpretationVariation in the HLA-C gene influences susceptibility to multiple sclerosis independently of any effect attributable to the nearby HLA-DRB1 gene.
Project description:The multi-subunit CCR4 (carbon catabolite repressor 4)-NOT (Negative on TATA) complex serves as a central coordinator of all different steps of eukaryotic gene expression. Accordingly, members of the CCR4-NOT complex have been implicated in a variety of biological functions. Here we performed a systematic and comparative analysis of cells where the CCR4-NOT subunits CNOT1, CNOT2 or CNOT3 were individually downregulated using doxycycline-inducible shRNAs. Microarray experiments showed that downregulation of either CNOT subunit resulted in elevated expression of major histocompatibility complex class II (MHC II) target genes which are found in a gene cluster on chromosome 6. Increased expression of MHC II genes after knock-down or knock-out of CNOT subunits was seen in a variety of cell systems and also in naïve macrophages from CNOT3 conditional knock-out mice. CNOT2-mediated repression of MHC II genes occurred independent from the master regulator class II transactivator (CIITA) and detectable changes of the chromatin structure at the chromosomal MHC II locus. CNOT2 downregulation resulted in an increased de novo transcription of mRNAs and tethering of CNOT2 to a regulatory region governing MHC II expression resulted in dimished transcription. These results expand the known repertoire of CCR4-NOT members for immune regulation and identify CNOT proteins as a novel group of corepressors serving to restrict inappropriate or exaggerated class II expression, which can be causative for various diseases.
Project description:Limited access to large samples and independent replication cohorts precludes genome-wide association (GWA) studies of rare but complex traits. To localize candidate genes in an on-going study utilizing family-based GWA, a novel exploratory analysis was first tested on 1,774 major histocompatibility complex single nucleotide polymorphisms (SNPs) in 240 DNA samples from 80 children with primary liver transplantation (LTx), and their biological parents. Genotyping was performed using the Illumina HumHap550k SNP BeadArray; the genotype calls for the 1813 SNPs in the MHC region are provided in the genotype_data.zip supplementary file linked to this series (see README file in the zip archive for more information). The Affymetrix Human Exon 1.0 ST array was used to measure differential splicing patterns in archived RNA isolated from 26 of 80 children for genes found near associated SNPs. This SuperSeries is composed of the SubSeries listed below.