Biology subjects

D'haene, E.

Publications and source records attributed to D'haene, E..

5 recordsLinked to original sources

bioRxiv2023

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

Vision 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 of cis-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 applying in situ Hi-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/or cis-regulatory interactions. One of these genes was ABCA4, which is implicated in the most common autosomal recessive IRD. We zoomed in on tissue-specific chromatin interactions at the ABCA4 locus using high-resolution UMI-4C assays. Upon integration with bulk and single-cell epigenomic datasets and in vivo enhancer assays in zebrafish, we revealed tissue-specific CREs interacting with ABCA4. 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. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=75 SRC="FIGDIR/small/543842v1_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@fd0d7dorg.highwire.dtl.DTLVardef@180a5bforg.highwire.dtl.DTLVardef@101aec1org.highwire.dtl.DTLVardef@1781d1d_HPS_FORMAT_FIGEXP M_FIG C_FIG

genomics↗

bioRxiv2022

A distant global control region is essential for normal expression of anterior HOXA genes during mouse and human craniofacial development.

Defects in embryonic patterning resulting in craniofacial abnormalities account for approximately 1/3 of birth defects. The regulatory programs that build and shape the face require precisely controlled spatiotemporal gene expression, achieved through tissue-specific enhancers. Large regions with coactivation of enhancer elements and co-regulation of multiple genes, referred to as superenhancers, are important in determining cell identity and perturbation could result in developmental defects. Building upon a previously published epigenomic atlas of human embryonic craniofacial tissue in which we identified over 75,000 putative embryonic craniofacial enhancer regions, we have identified 531 superenhancer regions unique to embryonic craniofacial tissue, including 37 which fall in completely noncoding regions. To demonstrate the utility of this data for the understanding of craniofacial development and the etiology of craniofacial abnormalities, we focused on a craniofacial-specific superenhancer in a [~]600kb noncoding region located between NPVF and NFE2L3. This region harbors over 100 individual putative craniofacial enhancer segments and 7 in vivo validated craniofacial enhancers from primary craniofacial tissue as well as strong enhancer activation signatures in a culture model of cranial neural crest cell (CNCC) development. However, none of the directly adjacent genes have been implicated in neural crest specification, craniofacial development, or abnormalities. To identify potential regulatory targets of this superenhancer region, we characterized three-dimensional chromatin structure of this region in CNCCs and mouse embryonic craniofacial tissues using multiple techniques (4C-Seq, HiC). We identified long range interactions that exclude most intervening genes and specifically target the anterior portion of the HOXA gene cluster located 1.2 to 1.8 Mb away. We demonstrate the specificity of the enhancer region for regulation of anterior HOXA genes through CRISPR/Cas9 editing of human embryonic stem cells. Mice homozygous for deletion of the superenhancer confirm the specificity of the enhancer region and demonstrate that the region is essential for viability. At fetal stages homozygotes develop at the same rate as heterozygous and wild type littermates but die at P0-P1 and have high penetrance of orofacial clefts that phenocopy previously described Hoxa2-/- mice. Moreover, we identified a de novo deletion partially overlapping the superenhancer in a human fetus with severe craniofacial abnormalities. This evidence suggests we have identified a critical noncoding locus control region that specifically regulates anterior HOXA genes and whose deletion is likely pathogenic in human patients.

developmental biology↗

bioRxiv2022

Multi-omics profiling, in vitro and in vivo enhancer assays dissect the cis -regulatory mechanisms underlying North Carolina macular dystrophy, a retinal enhanceropathy

North Carolina macular dystrophy (NCMD) is a rare autosomal dominant disease affecting macular development. The disease is caused by non-coding single nucleotide variants (SNVs) in two hotspot regions near PRDM13 and by duplications in two distinct chromosomal loci, overlapping DNase I hypersensitive sites near either PRDM13 or IRX1. To unravel the mechanisms by which these variants cause disease, we first established a genome-wide multi-omics retinal database, RegRet. Integration of UMI-4C profiles we generated on adult human retina then allowed fine-mapping of the interactions of the PRDM13 and IRX1 gene promoters, and the identification of eighteen candidate cis-regulatory elements (cCREs), the activity of which was investigated by luciferase and Xenopus enhancer assays. Next, luciferase assays showed that the non-coding SNVs located in the two hotspot regions of PRDM13 affect cCRE activity, including two novel NCMD-associated non-coding SNVs that we identified. Interestingly, the cCRE containing one of these SNVs was shown to interact with the PRDM13 promoter, demonstrated in vivo activity in Xenopus, and is active at the developmental stage when progenitor cells of the central retina exit mitosis, putting forward this region as a PRDM13 enhancer. Finally, mining of single-cell transcriptional data of embryonic and adult retina revealed the highest expression of PRDM13 and IRX1 when amacrine cells start to synapse with retinal ganglion cells, supporting the hypothesis that altered PRDM13 or IRX1 expression impairs interactions between these cells during retinogenesis. Overall, this study gained insight into the cis-regulatory mechanisms of NCMD and supports that this condition is a retinal enhanceropathy. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=149 SRC="FIGDIR/small/481329v2_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@4a85e3org.highwire.dtl.DTLVardef@9bfe55org.highwire.dtl.DTLVardef@156a9d8org.highwire.dtl.DTLVardef@a8cb92_HPS_FORMAT_FIGEXP M_FIG C_FIG

genomics↗

bioRxiv2022

Transcriptional and functional consequences of alterations to MEF2C and its topological organization in neuronal models

Point mutations and structural variants directly disrupting the coding sequence of MEF2C have been associated with a spectrum of neurodevelopmental disorders (NDDs), while recent studies have also implicated altered noncoding regulation of MEF2C expression in NDDs. However, the impact of haploinsufficiency of MEF2C on neurodevelopmental pathways and synaptic processes is not well understood, nor are the complex mechanisms that govern regulation of MEF2C. To explore the transcriptional and functional changes associated with coding and noncoding structural variants, we generated an allelic series of 204 isogenic iPSC-derived neuronal cell lines harboring CRISPR-engineered mutations that directly delete predominant isoforms of MEF2C, as well as deletions to the boundaries of topologically associating domains (TADs) and chromatin loops encompassing MEF2C. We then performed systematic profiling of mutation-specific alterations to transcriptional signatures, regulatory interactions, chromatin contacts, and electrophysiological effects. Our analyses reveal that direct deletion of MEF2C causes differential expression of genes enriched for neurodevelopmental and synaptic-associated pathways, accompanied by a significant reduction in synaptic firing and synchrony in neurons. By contrast, we observe robust buffering against MEF2C regulatory disruption upon deletion of a distal 5q14.3 TAD and loop boundary; however, homozygous loss of proximal loop boundary resulted in significant down-regulation of MEF2C expression and significantly reduced electrophysiological activity that was comparable to direct MEF2C disruption. Collectively, our findings demonstrate the functional impact of MEF2C haploinsufficiency in human-derived neural models and highlight the complex interactions of gene regulation and chromatin topology that challenge a priori regulatory predictions of structural variant disruption to three-dimensional genome organization.

genomics↗

bioRxiv2020

SOX11 is a lineage-dependency factor and master epigenetic regulator in neuroblastoma

The pediatric extra-cranial tumor neuroblastoma (NB) is characterised by a low mutation burden while copy number alterations are present in most high-risk cases. We identified SOX11 as a strong lineage dependency transcription factor in adrenergic NB based on recurrent chromosome 2p focal gains and amplifications, its specific expression in the normal sympatho-adrenal lineage and adrenergic NBs and its regulation by multiple adrenergic specific cis-interacting (super-)enhancers. Adrenergic NBs are strongly dependent on high SOX11 expression levels for growth and proliferation. Through genome-wide DNA-binding and transcriptome analysis, we identified and validated functional SOX11 target genes, several of which implicated in chromatin remodeling and epigenetic modification. SOX11 controls chromatin accessibility predominantly affecting distal adrenergic lineage-specific enhancers marked by binding sites of the adrenergic core regulatory circuitry. During normal sympathoblast differentiation we find expression of SOX11 prior to members of the adrenergic core regulatory circuitry. Given the broad control of SOX11 of multiple epigenetic regulatory complexes and its presumed pioneer factor function, we propose that adrenergic NB cells have co-opted the normal role of SOX11 as a crucial regulator of chromatin accessibility and cell identity.

cancer biology↗