Project description:We performed a Massively Parallel Reporter Assay (MPRA) to screen >30,000 human-specific substitutions in ChIP-seq-identified Human Gain Enhancers (HGEs) and Human Accelerated Regions (HARs), highly conserved non-coding regions that show accelerated sequence evolution in humans. After comparing human and chimpanzee reference alleles, we used a second MPRA to deconvolute individual substitutions within differentially active enhancers from substitutions in the same fragment and from other variants (human segregating variants or chimpanzee-specific variants) to isolate their specific effects on enhancer activity.
Project description:We performed a massively parallel reporter assay (MPRA) of 2,034 genomic regions containing single nucleotide polymorphisms (4,587 regions tested with 96,328 barcodes) that are in high linkage disequilibrium with lead variants from an asthma GWAS (PMID: 31036433). Test sequences were transfected into 16HBE14o- Human Bronchial Epithelial Cells, and assessed for enhancer activity by comparing RNA counts to DNA input counts. The processed files contain the MPRA barcodes, read counts and activities.
Project description:Human accelerated regions (HARs) are evolutionarily conserved sequences that acquired human-specific nucleotide changes and reside in genomic regions associated with unique human traits and disease. The majority of HARs (96%) are noncoding, a few of which have been shown to be functional enhancers. Here, we comprehensively tested human and chimpanzee sequences of HARs (N=714) for enhancer activity using a lentivirus-based massively parallel reporter assay (lentiMPRA) in human and chimpanzee iPSC derived neural progenitors at two differentiation time points. We found that 43% (306/714) function as enhancers and over two-thirds (204/306) showed consistent differences in activity between human and chimpanzee sequences across conditions. We also tested all possible permutations of substitutions in seven HARs and found significant positive and negative interactions. Our study provides a comprehensive resource of functional neurodevelopmental HAR enhancers and shows that multiple interacting sites drive evolutionary activity differences.
Project description:Human accelerated regions (HARs) are evolutionarily conserved sequences that acquired human-specific nucleotide changes and reside in genomic regions associated with unique human traits and disease. The majority of HARs (96%) are noncoding, a few of which have been shown to be functional enhancers. Here, we comprehensively tested human and chimpanzee sequences of HARs (N=714) for enhancer activity using a lentivirus-based massively parallel reporter assay (lentiMPRA) in human and chimpanzee iPSC derived neural progenitors at two differentiation time points. We found that 43% (306/714) function as enhancers and over two-thirds (204/306) showed consistent differences in activity between human and chimpanzee sequences across conditions. We also tested all possible permutations of substitutions in seven HARs and found significant positive and negative interactions. Our study provides a comprehensive resource of functional neurodevelopmental HAR enhancers and shows that multiple interacting sites drive evolutionary activity differences.
Project description:We examined three classes of noncoding regions with different patterns of conservation and constraint: Human Accelerated Regions (HARs), which show signatures of positive selection in the human lineage; experimentally validated neural Vista Enhancers (VEs); and candidate neural enhancers (CNEs). We interrogate the in vitro enhancer activity of HARs, VEs, and CNEs in capture-based massively parallel reporter assays (caMPRAs). We also perform random mutagenesis on HARs to assess the effeects of single nucleotide variants on enhancer activity.
