Mapping DNA interaction landscapes in psoriasis susceptibility loci highlights KLF4 as a target gene in 9q31

ABSTRACT: Background: Genome-wide association studies (GWAS) have uncovered many genetic risk loci for psoriasis, yet many remain uncharacterised in terms of the causal gene and their biological mechanism in disease. This is largely a result of the findings that over 90% of GWAS variants map outside of protein-coding DNA, and instead are enriched in cell type and stimulation-specific gene regulatory regions. Results: Here, we use a disease-focused Capture Hi-C (CHi-C) experiment to link psoriasis-associated variants with their target genes in psoriasis-relevant cell lines (HaCaT keratinocytes and My-La CD8+ T cells). We confirm previously assigned genes, suggest novel candidates and provide evidence for complexity at psoriasis GWAS loci. For one locus, uniquely, we combine further epigenomic evidence to demonstrate how a psoriasis-associated region forms a functional interaction with the distant (>500 kb) KLF4 gene. This interaction occurs between the gene and active enhancers in HaCaT cells, but not in My-La cells. We go on to investigate this long-distance interaction further with Cas9 fusion protein-mediated chromatin modification (CRISPR activation) coupled with RNA-seq, demonstrating how activation of the psoriasis associated enhancer upregulates known genes in the KLF4 pathway, specific to skin cells and apoptosis. Conclusions: Taken together, our study design provides a robust pipeline to follow up GWAS disease associated variants and implicate the causal genes, cell types, direction of effect and consequences, which are vital next steps for the functional translation of genetic findings into clinical benefit.

ORGANISM(S): Homo sapiens

PROVIDER: GSE137906 | GEO | 2020/04/10

REPOSITORIES: GEO