Project description:Genome-wide association studies (GWAS) have uncovered thousands of single nucleotide polymorphisms (SNPs) that are associated with Parkinson's disease (PD) risk. The functions of most of these SNPs, including the cell type they influence, and how they affect PD etiology remain largely unknown. To identify functional SNPs, we aligned PD risk SNPs within active regulatory regions of DNA in microglia, a cell type implicated in PD development. Out of 6,749 ‘SNPs of interest’ from the most recent PD GWAS metanalysis, 73 were located in open regulatory chromatin as determined by both ATAC-seq and H3K27ac ChIP-seq. We identified an active enhancer in microglia in intron two of SNCA that overlaps two PD risk SNPs, rs2737004 and rs2619356. In iPSC-derived microglia, CRISPR/Cas9 deletion of the open chromatin encompassing these SNPs caused reduced expression of multiple genes including SNCA and the adjacent gene MMRN1. Loss of the enhancer also led to upregulation of genes involved in glucose metabolism, a process that is known to be altered in PD patients. Our work expands the role of SNCA in Parkinson’s Disease and provides a connection between PD-associated genetic variants and underlying biology that points to a risk mechanism in microglia.
Project description:Genome-wide association studies (GWAS) have uncovered thousands of single nucleotide polymorphisms (SNPs) that are associated with Parkinson's disease (PD) risk. The functions of most of these SNPs, including the cell type they influence, and how they affect PD etiology remain largely unknown. To identify functional SNPs, we aligned PD risk SNPs within active regulatory regions of DNA in microglia, a cell type implicated in PD development. Out of 6,749 ‘SNPs of interest’ from the most recent PD GWAS metanalysis, 73 were located in open regulatory chromatin as determined by both ATAC-seq and H3K27ac ChIP-seq. We identified an active enhancer in microglia in intron two of SNCA that overlaps two PD risk SNPs, rs2737004 and rs2619356. In iPSC-derived microglia, CRISPR/Cas9 deletion of the open chromatin encompassing these SNPs caused reduced expression of multiple genes including SNCA and the adjacent gene MMRN1. Loss of the enhancer also led to upregulation of genes involved in glucose metabolism, a process that is known to be altered in PD patients. Our work expands the role of SNCA in Parkinson’s Disease and provides a connection between PD-associated genetic variants and underlying biology that points to a risk mechanism in microglia.
Project description:Genome-wide association studies have identified thousands of single nucleotide polymorphisms that associate with increased risk for Parkinson's disease (PD), but the functions of most of them are unknown. Using assay for transposase-accessible chromatin (ATAC) and H3K27ac chromatin immunoprecipitation (ChIP) sequencing data, we identified 73 regulatory elements in microglia that overlap PD risk SNPs. To determine the target genes of a "risk enhancer" within intron two of SNCA, we used CRISPR-Cas9 to delete the open chromatin region where two PD risk SNPs reside. The loss of the enhancer led to reduced expression of multiple genes including SNCA and the adjacent gene MMRN1. It also led to expression changes of genes involved in glucose metabolism, a process that is known to be altered in PD patients. Our work expands the role of SNCA in PD and provides a connection between PD-associated genetic variants and underlying biology that points to a risk mechanism in microglia.
Project description:Metazoan SAGA and ATAC are distinct multi-subunits complexes that share the same catalytic HAT subunit (GCN5 or PCAF). Here we show that these human HAT complexes are targeted to different genomic loci representing functionally distinct regulatory elements both at broadly expressed and tissue specific genes. While SAGA can principally be found at promoters, ATAC is recruited to promoters and enhancers, yet only its enhancer binding is cell-type specific. Furthermore, we show that ATAC functions at a set of enhancers that are not bound by p300, revealing a new class of enhancers not yet identified. These findings demonstrate important functional differences between SAGA and ATAC coactivator complexes at the level of the genome and define a novel role for the ATAC complex in the regulation of a set of enhancers. Examination of SPT20 in two different cell types.
Project description:Microglia play a key role in the response to amyloid beta in Alzheimer’s disease (AD). In this context, the major transcriptional response of microglia is the upregulation of APOE, the strongest late-onset AD risk gene. Of its three isoforms, APOE2 is thought to be protective, while APOE4 increases AD risk. We hypothesised that the isoforms functionally alter microglia by shaping their transcriptomic and chromatin landscapes. We used ATAC- and ATAC-sequencing to profile gene expression and chromatin accessibility of human microglia isolated from a xenotransplantation model of AD. We identified widespread transcriptomic and epigenomic differences which are dependent on APOE genotype, and are corroborated across the profiling assays.
Project description:We describe that during early zebrafish development, DNA methylation has little influence on enhancer activity, and that hypo-methylation is a unique feature of primed enhancers, whereas active enhancers are generally hyper-methylated. Hypo-methylated enhancers (hypo-enhancers) are enriched close to important transcription factors (TFs) that act later in development, are specifically de-methylated before the mid blastula transition (MBT), and reside in a unique epigenetic environment. Finally, we demonstrate that hypo-enhancers are functionally active later in development and that they are physically associated with the transcriptional start site (TSS) of target-genes, irrespective of target-gene activity. we analyzed 5 novel ChIP-Seq libraries where we used the following AB (H3K27ac,H3K4me1,H3K4me2 and H3K27ac) and an Atac-Seq library.