Project description:<p>Our study identified candidate regions of genome involved in adaptation and identified regions associated with selected phenotypes.</p>
Project description:Natural genetic variation between two mouse strains was used as a natural mutagenesis screen to test various aspects of the proposed model for enhancer selection and function.
Project description:<p>Our study identified candidate regions of genome involved in adaptation and identified regions associated with selected phenotypes.</p>
Project description:Natural genetic variation between two mouse strains was used as a natural mutagenesis screen to test various aspects of the proposed model for enhancer selection and function. Chromatin marks H3K4me2, H3K27Ac, and transcription factors PU.1, C/EBPa, and p65 were assessed by ChIP-Seq and GRO-Seq and RNA-Seq were used to measure gene expression in C57BL6/J and BALBc/J inbred mouse strains
Project description:In Arabidopsis thaliana a high rate of spontaneous epigenetic variation can occur in the DNA methylome in the absence of genetic variation and selection. It has been of great interest, whether natural epigenetic variation is subject to selection and contributes to fitness and adaptation in selective environments. We compared the variation in selected phenotypic traits, genome-wide cytosine DNA methylation and gene expression in two Arabidopsis recombinant inbred lines, which had undergone five generations of selection in experimental landscapes relative to their genetically identical ancestors. Selected populations exerted significant differences in flowering time and the number of branches and fruits, differences that were maintained over two to three generations in the absence of selection. We identified 4,629 and 5,158 differentially methylated cytosines which were overrepresented in genes that regulate flowering time, epigenetic processes, development and morphogenesis. Differentially methylated genes were enriched in differentially expressed genes. Thus, epigenetic variation is subject to selection and may play an important role in the adaptive response of populations in rapidly changing natural environments.
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: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.