GSE168045
An autoimmune pleiotropic SNP modulates IRF5 alternative promoter usage through ZBTB3-mediated chromatin looping
Genetic sharing is extensively observed for many autoimmune diseases, but the causal variants and their underlying molecular mechanisms remain largely unknown. Through systematic investigation of known autoimmune disease pleiotropic loci, we found that most of these genetic effects are transmitted from regulatory code and colocalize with hematopoietic lineage-specific expression quantitative trait loci. We used an evidence-based strategy to functionally prioritize known pleiotropic variants and identify their target genes. A top-ranked pleiotropic variant, rs4728142, yielded many lines of evidence as being causal, and regulates IRF5 transcript expression. Mechanistically, the rs4728142-containing region interacts with the IRF5 downstream alternative promoter in an allele-specific manner and orchestrates its upstream enhancer to regulate IRF5 alternative promoter usage through chromatin looping. A putative structural regulator, ZBTB3, mediates the allele-specific chromatin looping to promote IRF5 short transcript expression at the rs4728142 risk allele, resulting in IRF5 overactivation and M1 macrophage polarization. Together, our findings establish a causal mechanism between the regulatory variant and fine-scale molecular phenotype underlying the dysfunction of pleiotropic genes in human autoimmunity. Overall design: Examination of ATAC-seq, 6 different ChIP-seq, and 2 different 4C-seq in SC cells, and RNA-Seq in the rs4728142 locus destruction (sKO) and unedited (control) SC-Cas9 cells