Project description:Skin color is highly variable in Africans, yet little is known about the underlying molecular mechanism. We identified 1,157 candidate variants influencing skin pigmentation in indigenous Africans by genome-wide association studies and scans of natural selection based on differentiation in allele frequencies between lightly pigmented southern African Khoesan populations and other darkly pigmented African populations. We applied massively parallel reporter and chromosome conformation capture assays to identify novel regulatory variants and their target genes related to skin pigmentation in melanocytic cells. We identified 165 SNPs showing strong differential regulatory activities between alleles. Combining CRISPR-mediated genome editing, transcriptome profiling and melanin assays, we identified causal regulatory variants impacting pigmentation near MFSD12/HMG20B, MITF, OCA2, and DDB1/CYB561A3/TMEM138. We identified CYB561A3 as a novel gene regulating pigmentation by impacting genes involved in oxidative phosphorylation and melanogenesis. Our results broaden our understanding of the genetic basis of human skin color diversity and human adaptation. To test the role of candidate enhancers and variants in skin pigmentation, we performed CRISPR inhibition or knockout of enhancers containing the functional variants identified by MPRA in melanocytic cells. Then, we performed gene expression profiling analysis using data obtained from RNA-seq of these CRISPR-edited cells. We also performed RNA-seq using CYB561A3-koncout MNT1 cells or CYB561A3-overexpressing MNT1 cells
Project description:In African Americans (AA), the proportion of West African ancestry (WAA) may explain the genetic drivers of health disparities in disease. Analysis of RNA sequencing data from sixty AA-derived primary hepatocytes identified 32 gene expression profiles associated with WAA (FDR <0.05) with enrichment in angiogenesis and inflammatory pathways (FDR <0.1). Association of DNA methylation to WAA identified 1037 differentially methylated regions (FDR <0.05), with hypomethylated genes enriched for drug response pathways. Within the PharmGKB pharmacogene, VDR, PTGIS, ALDH1A1, CYP2C19 and P2RY1 were associated with WAA (p <0.05) with replication of CYP2C19 and VDR in the GTEx liver cohort. For every 1% increment in WAA, P2RY1 gene expression increased by 1.6% and CYP2C19 gene expression decreased by 1.4%, suggesting effects on clopidogrel response and platelet aggregation. We conclude that WAA contributes to variablity in hepatic gene expression and DNA methylation with identified genes indicative of health disparities prevalent in AAs.
Project description:Skin color is highly variable in Africans, yet little is known about the underlying molecular mechanism. We identified 1,157 candidate variants influencing skin pigmentation in indigenous Africans by genome-wide association studies and scans of natural selection based on differentiation in allele frequencies between lightly pigmented southern African Khoesan populations and other darkly pigmented African populations. We applied massively parallel reporter and chromosome conformation capture assays to identify novel regulatory variants and their target genes related to skin pigmentation in melanocytic cells. We identified 165 SNPs showing strong differential regulatory activities between alleles. Combining CRISPR-mediated genome editing, transcriptome profiling and melanin assays, we identified causal regulatory variants impacting pigmentation near MFSD12/HMG20B, MITF, OCA2, and DDB1/CYB561A3/TMEM138. We identified CYB561A3 as a novel gene regulating pigmentation by impacting genes involved in oxidative phosphorylation and melanogenesis. Our results broaden our understanding of the genetic basis of human skin color diversity and human adaptation. To decipher the target genes of the MFVs, we performed Hi-C and H3K27ac HiChIP assays in MNT1 cells. Hi-C is a high-throughput method for detecting chromatin interactions at whole genome scale and is often used to identify topologically associating domains (TADs) in the nucleus. H3K27ac HiChIP can identify chromatin interactions enriched for H3K27ac, a histone modification associated with active promoters and enhancers. We performed bridge linker mediated Hi-C and H3K27ac HiChIP using double (Hae3_Alu1) as well as single (Hae3) enzyme digestion in MNT-1 cells.
Project description:In African Americans (AA), the proportion of West African ancestry (WAA) may explain the genetic drivers of health disparities in disease. Analysis of RNA sequencing data from sixty AA-derived primary hepatocytes identified 32 gene expression profiles associated with WAA (FDR <0.05) with enrichment in angiogenesis and inflammatory pathways (FDR <0.1). Association of DNA methylation to WAA identified 1037 differentially methylated regions (FDR <0.05), with hypomethylated genes enriched for drug response pathways. Within the PharmGKB pharmacogene, VDR, PTGIS, ALDH1A1, CYP2C19 and P2RY1 were associated with WAA (p <0.05) with replication of CYP2C19 and VDR in the GTEx liver cohort. For every 1% increment in WAA, P2RY1 gene expression increased by 1.6% and CYP2C19 gene expression decreased by 1.4%, suggesting effects on clopidogrel response and platelet aggregation. We conclude that WAA contributes to variablity in hepatic gene expression and DNA methylation with identified genes indicative of health disparities prevalent in AAs.
Project description:In African Americans (AA), the proportion of West African ancestry (WAA) may explain the genetic drivers of health disparities in disease. Analysis of RNA sequencing data from sixty AA-derived primary hepatocytes identified 32 gene expression profiles associated with WAA (FDR <0.05) with enrichment in angiogenesis and inflammatory pathways (FDR <0.1). Association of DNA methylation to WAA identified 1037 differentially methylated regions (FDR <0.05), with hypomethylated genes enriched for drug response pathways. Within the PharmGKB pharmacogene, VDR, PTGIS, ALDH1A1, CYP2C19 and P2RY1 were associated with WAA (p <0.05) with replication of CYP2C19 and VDR in the GTEx liver cohort. For every 1% increment in WAA, P2RY1 gene expression increased by 1.6% and CYP2C19 gene expression decreased by 1.4%, suggesting effects on clopidogrel response and platelet aggregation. We conclude that WAA contributes to variablity in hepatic gene expression and DNA methylation with identified genes indicative of health disparities prevalent in AAs.