Project description:The lysine-specific demethylase 2A gene (KDM2A) is ubiquitously expressed and its transcripts consist of several alternatively spliced forms, including KDM2A and the shorter form N782 that lacks the 3’ end encoding F-box and LRR. KDM2A binds to numerous CpG-rich genomic loci and regulates various cellular activities; however, the mechanism of the pleiotropic function is unknown. Here, we identify the mechanism of KDM2A played by its CXXC-PHD domain. KDM2A is necessary for a rapid proliferation of post-natal keratinocytes while its 3’ end eclipses the stimulatory effect. EGFP-N782 binds to chromatin together with the XRCC5/6 complex, and the CXXC-PHD domain regulates the CpG-rich IGFBPL1 promoter. In vitro, CXXC-PHD enhances binding of nuclear extract ORC3 to the CpG-rich promoter, but not to the AT-rich DIP2B promoter to which ORC3 binds constitutively. Furthermore, CXXC-PHD recruits 94 nuclear factors involved in replication, ribosome synthesis, and mitosis, including POLR1A to the IGFBPL1 promoter. This recruitment is unprecedented; however, the result suggests that these nuclear factors bind to their cognate loci, as substantiated by the result that CXXC-PHD recruits POLR1A to the rDNA promoter. We propose that CXXC-PHD promotes permissiveness for nuclear factors to interact, but involvement of the XRCC5/6 complex in the recruitment is undetermined.
Project description:The dysregulation of plant homeodomain (PHD) fingers has been implicated in several human diseases, including cancer. In a subset of aggressive acute myeloid leukemia (AML), chromosomal translocations that involve nucleoporin 98 (NUP98), a component of the nuclear pore complex, and a PHD finger-containing protein, such as KDM5A/JARID1A, PHF23 and BPTF, generate potent oncoproteins (namely NUP98-KDM5A, NUP98-PHF23 and NUP98-BPTF; or together termed as NUP98-PHD fusions) that are able to arrest hematopoietic differentiation and induce acute myeloid leukemia in murine models. In these processes, a PHD finger that specifically recognizes H3K4me3/2 marks was essential for leukemogenesis. Mutations in PHD fingers that abrogated H3K4me3 binding also abolished leukemic transformation. An overlap of NUP98-KDM5A oncoprotein binding sites and H3K4me3-positive loci at the Hoxa/b gene clusters and Meis1 in ChIP-seq together with NMR analysis of the H3K4me3-binding sites of the PHD fingers from PHF23, KDM5A and BPTF suggests a common PHD finger-dependent mechanism that promotes leukemogenesis by this type of NUP98-PHD finger fusions. Disulfiram (DS), a small molecule compound that directly targets the PHD finger, shows anti-proliferation effects in AML cells expressing NUP98-PHD through the conserved inhibitory mechanism. Our findings highlight the direct correlation between the abilities of NUP98-PHD finger fusion chimeras to associate with H3K4me3-enriched chromatin and leukemic transformation.
Project description:Chromatin remodeling and histone modifications are important for development and floral phase transition in plants. However, it is largely unknown whether and how these two epigenetic regulators coordinately regulate the important biological processes. Here, we identified three types of ISWI chromatin remodeling complexes in Arabidopsis thaliana. We found that ARID5, a subunit of a plant-specific ISWI complex, can regulate development and floral phase transition. The ARID-PHD dual domain cassette of ARID5 recognizes both the H3K4me3 histone mark and AT-rich DNA. We determined the ternary complex structure of the ARID5 ARID-PHD cassette with an H3K4me3 peptide and an AT-containing DNA. The H3K4me3 peptide is combinatorially recognized by the PHD and ARID domains, while the DNA is specifically recognized by the ARID domain. Both PHD and ARID domains are necessary for the association of ARID5 with chromatin. The results suggest that the dual recognition of AT-rich DNA and H3K4me3 by the ARID5 ARID-PHD cassette may facilitate the association of the ISWI complex with specific chromatin regions to regulate development and floral phase transition
Project description:To identify a cohort of rhythmically expressed genes in the murine Distal Colon,microarrays were used to measure gene expression over a 24-hour light/dark cycle.The rhythmic transcripts were classified according to expression patterns, functions and association with physiological and pathophysiological processes of the colon including motility, colorectal cancer formation and inflammatory bowel disease. Experiment Overall Design: Mice were maintained for 2 weeks on a 12 hour light/dark (LD) cycle (lights on 7 AM, lights off 7 PM) prior to all experiments. For the reference experiment, mice had ad libitum access to food. Samples were collected every four hours, at 0400, 0800, 1200, 1600, 2000 and 2400, starting 1 hour after the lights went on. Total RNA was isolated by modified guanidinium thicyanate-phenol-chloroform extraction method and was treated with DNase I (Promega, Madison, WI) at 37 oC for 30 minutes.Hybridizations and Scaning were done as per Affymetrix techniques. Three MOE 430 plus 2.0 chips were used per time point.
Project description:Lipid homeostasis is dysregulated in several forms of neurodegeneration. Here we examined changes in sterols, neutral lipids and transcripts that control their homeostasis during the neuronal death induced in the CA1 region of mouse hippocampus by focal kainic acid (KA) injection. We defined changes in the lipid economy of neurons and glial cells by staining for neutral lipids and for free cholesterol. Lipid droplets filled with neutral lipids were induced in microglia at ~24 hrs after KA-treatment. At 2-4 days after injection, filipin staining revealed punctate deposits of free cholesterol in neuronal somata. These changes were correlated with alterations in cellular organelles observed in electron microscopy and transcriptomic changes obtained with RNA-seq of tissue from the CA1 region. Mitochondria, the innate inflammatory response and lipids. Lipid droplet transcriptome. Cholesterol economy. Lipids and phagocytosis.
Project description:Mutations in PHF8 are associated with X-linked mental retardationand cleft lip/cleft palate. PHF8 contains a plant homeodomain(PHD) in its N-terminus and is member of a family of JmjC-domaincontaining proteins. While PHDs can act as methyl lysine recognitionmotifs, JmjC-domains can catalyze lysine demethylation. Here,we show that PHF8 is a histone demethylase that removes repressivehistone H3 dimethyl lysine 9 marks. Our biochemical analysisrevealed specific association of the PHF8 PHD domain with histoneH3 trimethylated at lysine 4 (H3K4me3). Chromatin-immunoprecipitationfollowed by high throughput sequencing indicated that PHF8 isenriched at transcription start sites of many active or poisedgenes, mirroring the presence of RNA polymerase II (RNAPII)and of H3K4me3-bearing nucleosomes. We show that PHF8 can actas a transcriptional co-activator and its activation functionlargely depends on binding of the PHD to H3K4me3. Furthermore,we present evidence for direct interaction of PHF8 with theC-terminal domain of RNAPII. Importantly, a PHF8 disease mutantis defective in demethylation and in co-activation. This isthe first demonstration of a chromatin-modifying enzyme whichis globally recruited to promoters through its association withH3K4me3 and RNAPII. This SuperSeries is composed of the following subset Series: GSE20563: Knockdown of PHF8 in HeLa S3 cells GSE20725: ChIP-Seq of PHF8 and H3K4me3 Refer to individual Series