Multi-disease associated risk locus in IL6 represses the anti-inflammatory gene GPNMB through chromatin looping and recruiting MEF2-HDAC complex

Abstract

We have previously revealed a genetic association between Takayasu arteritis and a non-coding genetic variant in an enhancer region within IL6 (rs2069837 A/G). The risk allele in this variant (allele A) has a protective effect against chronic viral infection and cancer. Using a combination of experimental and bioinformatics tools, we identified the monocyte/macrophage anti-inflammatory gene GPNMB, [~]520kb away, as a target gene regulated by rs2069837. We revealed preferential recruitment of myocyte enhancer factor 2-histone deacetylase (MEF2-HDAC) repressive complex to the Takayasu arteritis risk allele. Further, we demonstrated suppression of GPNMB expression in monocyte-derived macrophages from healthy individuals with the AA compared to AG genotype, which was reversed by histone deacetylase inhibition. Our data suggest that the A allele in rs2069837 represses the expression of GPNMB by recruiting MEF2-HDAC complex, enabled through a long-range intra-chromatin looping mediated by CTCF. Suppression of this anti-inflammatory gene might mediate increased susceptibility in Takayasu arteritis and enhance protective immune responses in chronic infection and cancer. Our data highlight long-range chromatin interactions in functional genomic studies.