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: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.
Project description:We performed a massively parallel reporter assay on 2,396 genomic regions containing single nucleotide polymorphisms that are in high linkage disequilibrium with 97 lead variants from an obesity GWAS (PMID: 25673413). Regions were transfected into human SGBS preadipocytes, SGBS mature adipocytes, 3T3-L1 preadipocytes, HT22 hippocampal cells, and GT1-7 cells and assessed for enhancer activity. The processed file contains the MPRA barcodes.
Project description:Human Accelerated Regions (HARs) are the fastest-evolving regions of the human genome and many are hypothesized to function as regulatory elements that drive human-specific gene regulatory programs. We interrogate the in vitro enhancer activity of >3,100 HARs in massively parallel reporter assays (MPRAs), demonstrating that many HARs appear to act as neural enhancers and that sequence divergence at HARs has largely augmented their neuronal enhancer activity.
Project description:Homo sapiens and Macaca fascicularis neural progenitor cell lines were transduced with a lentiviral MPRA (Massively Parallel Reporter Assay) library. MPRA barcode sequencing and RNA-seq was performed on the extracted RNA. MPRA data was used to compare activity of regulatory sequences across 75 mammalian species with a focus on primates and correlate these activities with the Phenotype of gyrencephaly.
