Comparative 3D genome analysis between neural retina and RPE reveals differentialcis-regulatory interactions at retinal disease loci

Abstract

ABSTRACTVision depends on the functional interplay between the photoreceptor cells of the neural retina and the supporting cells of the underlying retinal pigment epithelium (RPE). Most genes involved in inherited retinal diseases (IRD) display highly specific spatiotemporal expression within these interconnected retinal components through the local recruitment ofcis-regulatory elements (CREs) in 3D nuclear space.To understand the role of differential chromatin architecture in establishing tissue-specific expression patterns at IRD loci in the human neural retina and the RPE, we mapped genome-wide chromatin interactions by applyingin situHi-C and H3K4me3 HiChIP to human adult post-mortem donor retinas. A comparative 3D genome analysis between neural retina and RPE/choroid revealed that almost 60% of 290 known IRD genes were marked by differential 3D genome structure and/orcis-regulatory interactions. One of these genes wasABCA4, which is implicated in the most common autosomal recessive IRD. We zoomed in on tissue-specific chromatin interactions at theABCA4locus using high-resolution UMI-4C assays. Upon integration with bulk and single-cell epigenomic datasets andin vivoenhancer assays in zebrafish, we revealed tissue-specific CREs interacting withABCA4.In summary, through extensive comparative 3D genome mapping, based on genome-wide (Hi-C), promoter-centric (HiChIP) and locus-specific (UMI-4C) assays of human neural retina and RPE, we have shown that gene regulation at key IRD loci is likely mediated by tissue-specific chromatin interactions. These findings do not only provide insight into tissue-specific regulatory landscapes of IRD genes, but also delineate the search space for non-coding genomic variation underlying unsolved IRD.Abstract Figure