Project description:Histone ubiquitination has been suggested to serve as a “tag” for nucleosome removal during histone-to-protamine exchange that is essential for chromatin packaging in round spermatids. Here, we screen for putative E3 ligase and identify that the PHF7, containing both RING finger and PHD domains, is critical for H2A ubiquitination and histone removal. Mechanistically, its PHD domain as a histone code reader can specifically bind H3K4me3/me2 and its RING domain as a histone writer can ubiquinate H2A. So we want to use ChIP-seq to see whether all PHF7-binding peaks overlapped with those of H3K4me3. We report the application of ChIP-seq for high-throughput profiling of histone modifications in spermatids. By obtaining over 240M of sequences from chromatin immunoprecipitated DNA, we generated genome-wide chromatin-state maps and PHF7 binding position of late spermatids. We find binding peaks of PHF7, H3K4me3 and ub-H2A were mainly enriched at gene-regulatory elements (-5kb to +5kb from transcriptional start site), including promoter and enhancers, indicative of important roles in gene regulations. More than 96% (n=15419) of all PHF7-binding peaks overlapped with those of H3K4me3, supporting a specific binding of PHF7 to H3k4me3. Moreover, the common binding sites between PHF7 and H3K4me3 were associated with ub-H2A. Taken together, these results demonstrate that PHF7 ubiquitinate H2A through binding with H3K4me3.
Project description:Polycomb repressive complex 1 (PRC1) catalyzes H2A monoubiquitination (uH2A) and regulates pluripotency in embryonic stem cells (ESCs). However the mechanisms controlling PRC1 recruitment and activity are largely unknown. Here we show that Fbxl10 interacts with Ring1B and Nspc1, forming a non-canonical PRC1. We demonstrate that Fbxl10-PRC1 is essential for H2A ubiquitination in mouse ESCs. Genome-wide analyses reveal that Fbxl10 preferentially binds to CpG islands and co-localizes with Ring1B on Polycomb target genes. Notably, Fbxl10 depletion causes modest dissociation of Ring1B but a major loss of uH2A on target genes. Furthermore rescue experiments for Fbxl10 reveal that its DNA binding capability and integration into PRC1 are required for proper H2A ubiquitination. ES cells lacking Fbxl10, like previously characterized Polycomb mutants, show a severely compromised capacity for successful differentiation. Our results shed light on a novel mechanism how CpG islands regulate chromatin function by affecting polycomb recruitment and activity. All ChIP-seq reactions were performed in either untransfected cells, cells expressing scrambled shRNA or Fbxl10 shRNA, Ring1b-/- or Suz12-/- mouse ES cells
Project description:Histone ubiquitination has been suggested to serve as a “tag” for nucleosome removal during histone-to-protamine exchange that is essential for chromatin packaging in round spermatids. Here, we screen for putative E3 ligase and identify that the PHF7, containing both RING finger and PHD domains, is critical for H2A ubiquitination and histone removal. Mechanistically, its PHD domain as a histone code reader can specifically bind H3K4me3/me2 and its RING domain as a histone writer can ubiquinate H2A. PHF7 deficiency results in male infertility in mice by generating Phf7 knockout mice using CRISPR-Cas9 technology. Futhermore, we find impaired histone-to-protamine exchange leads to reduced chromatin compaction in Phf7 knockout sperm. Immunostaining and western blot further confirme abnormal retention of core histones and reduced levels of protamine PRM1 and PRM2 in Phf7 knockout sperm. In order to exclude the possibility that Phf7 regulate the expession of protamine, we sorte the round spermatids from WT and Phf7 knockout females for RNA-seq. The transcriptomes in round spermatids are very similar between WT and Phf7 knockout mice. There are few differentially expressed genes in the two groups and the expression of protamine is also unchanged even if PHF7 deficiency. Therefore we find PHF7 has no effects on gene regulation in histone-to-protamine exchange.
Project description:Polycomb repressive complex 1 (PRC1) catalyzes H2A monoubiquitination (uH2A) and regulates pluripotency in embryonic stem cells (ESCs). However the mechanisms controlling PRC1 recruitment and activity are largely unknown. Here we show that Fbxl10 interacts with Ring1B and Nspc1, forming a non-canonical PRC1. We demonstrate that Fbxl10-PRC1 is essential for H2A ubiquitination in mouse ESCs. Genome-wide analyses reveal that Fbxl10 preferentially binds to CpG islands and co-localizes with Ring1B on Polycomb target genes. Notably, Fbxl10 depletion causes modest dissociation of Ring1B but a major loss of uH2A on target genes. Furthermore rescue experiments for Fbxl10 reveal that its DNA binding capability and integration into PRC1 are required for proper H2A ubiquitination. ES cells lacking Fbxl10, like previously characterized Polycomb mutants, show a severely compromised capacity for successful differentiation. Our results shed light on a novel mechanism how CpG islands regulate chromatin function by affecting polycomb recruitment and activity.
Project description:HIF2A(EPAS1) geenome_wide localization by Cut & Tag in MRC5 human fibroblasts ectopically expressing HIF2A in the pBabe vector, and in control MRC5 human fibroblasts containing only the pBabe vector. 2 biological replicates were done for the MRC5-HIF2A cells. Cut & Tag with an anti-H3-K27me3 Ab was done as a positive control for the Cut & Tag experiments.