Project description:This SuperSeries is composed of the following subset Series: GSE22477: PHF8 mediates histone demethylation events in cell cycle progression [expression] GSE22478: PHF8 mediates histone demethylation events in cell cycle progression [ChIP-Seq] Refer to individual Series
Project description:PHF8 (PHD Finger 8) mutations have been found in patients with X-linked mental retardation (XLMR) and craniofacial deformities. Here we identify PHF8 as the first enzyme that mediates demethylation of mono-methylated histone H4 lysine (K) 20 (H4K20me1), with additional activities towards H3K9me2/1 and H3K27me2. Patient mutations significantly compromise the demethylase activity, indicating functional importance. ChIP-seq identified PHF8 near the transcription start sites (TSS) of over 7000 target genes as well as in gene bodies and intergenic regions. PHF8 depletion resulted in up-regulation of H4K20me1 and H3K9me1 at the TSS-associated sites, and H3K9me2 in the gene bodies and intergenic regions, respectively, demonstrating differential substrate specificities at different target genomic locations. PHF8 depletion at the TSS results in decreased target gene expression, which is coincident with increased occupancy of the protein L3MBTL1 previously shown to induce chromatin compaction via binding to lower methyl states including H4K20me1 and H3K9me1. PHF8 RNAi and control RNAi stable HeLa cell lines were established. RNA were isolated from triplicate cell cultures. RNAs were subject to microarray expression analysis. Hybridizations were performed in duplicate.
Project description:PHF8 (PHD Finger 8) mutations have been found in patients with X-linked mental retardation (XLMR) and craniofacial deformities. Here we identify PHF8 as the first enzyme that mediates demethylation of mono-methylated histone H4 lysine (K) 20 (H4K20me1), with additional activities towards H3K9me2/1 and H3K27me2. Patient mutations significantly compromise the demethylase activity, indicating functional importance. ChIP-seq identified PHF8 near the transcription start sites (TSS) of over 7000 target genes as well as in gene bodies and intergenic regions. PHF8 depletion resulted in up-regulation of H4K20me1 and H3K9me1 at the TSS-associated sites, and H3K9me2 in the gene bodies and intergenic regions, respectively, demonstrating differential substrate specificities at different target genomic locations. PHF8 depletion at the TSS results in decreased target gene expression, which is coincident with increased occupancy of the protein L3MBTL1 previously shown to induce chromatin compaction via binding to lower methyl states including H4K20me1 and H3K9me1. HeLa cells stably expressing control and PHF8 shRNA were used to profile the histone modifications including H4K20me1, H3K9me1 and 2 by ChIP-seq. For PHF8 ChIP-seq, chromatin was obtained by formaldehyde cross-link and sonication. For chIP-seq of Histone modifcation, chromatin was prepared by MNase digestion to obtain mono-nucleosomes.
Project description:While reversible histone modifications are linked to an ever-expanding range of biological functions, the demethylases for histone H4 lysine 20 and their potential regulatory roles remain unknown. Here, we report that the PHD and Jumonji C (JmjC) domain-containing protein, PHF8, while utilizing multiple substrates, including H3K9me1/2 and H3K27me2, also functions as an H4K20me1 demethylase. PHF8 is recruited to promoters by its PHD domain based on interaction with H3K4me2/3 and controls G1/S transition in conjunction with E2F1, HCF-1 and Set1A, at least in part, by removing the repressive H4K20me1 mark from a subset of E2F1-regulated gene promoters. Phosphorylation-dependent PHF8 dismissal from chromatin in prophase is apparently required for the accumulation of H4K20me1 during early mitosis, which might represent a component of the Condensin II loading process. Accordingly, the HEAT repeat clusters in two non-SMC Condensin II subunits, N-CAPD3 and N-CAPG2, are capable of recognizing H4K20me1, and ChIP-seq. analysis demonstrate a significant overlap of Condensin II and H4K20me1 sites in mitotic HeLa cells. Thus, the identification and characterization of an H4K20me1 demethylase, PHF8, has revealed an intimate link between this enzyme and two distinct events in cell cycle progression. Keywords: Expression profiling by array HeLa cells were transfected with either control or PHF8 siRNAs. Experiments were performed in biological duplicates. RNA were extracted and sujected to microarray analysis.
Project description:PHF8 is a histone demethylase associated with X-linked mental retardation (XLMR). It has been described as a transcriptional coactivator involved in cell cycle progression, but its physiological role is still poorly understood. Here we show that PHF8 controls the expression of genes involved in cell adhesion and cytoskeleton organization such as RhoA, Rac1 and GSK3M-NM-2. A lack of PHF8 not only results in a cell cycle delay but also in a disorganized actin cytoskeleton and impaired cell adhesion. Our data demonstrate that PHF8 directly regulates the expression of these genes by demethylating H4K20me1 at promoters. Moreover, c-Myc transcription factor interacts with PHF8 and binds to the analyzed promoters, suggesting that c-Myc is involved on PHF8 recruitment to these promoters. Further analysis in the neuroblastoma cell line SH-SY5Y and in cortical neurons shows that depletion of PHF8 results in deficient neurite elongation. Overall, our results suggest that the mental retardation phenotype associated with loss of function of PHF8 could be due to abnormal neuronal connections as a result of alterations in cytoskeleton function. HeLa cells were transfected with either control or PHF8 siRNAs. Experiments were performed in biological triplicates. RNA were extracted and sujected to microarray analysis.
Project description:While reversible histone modifications are linked to an ever-expanding range of biological functions, the demethylases for histone H4 lysine 20 and their potential regulatory roles remain unknown. Here, we report that the PHD and Jumonji C (JmjC) domain-containing protein, PHF8, while utilizing multiple substrates, including H3K9me1/2 and H3K27me2, also functions as an H4K20me1 demethylase. PHF8 is recruited to promoters by its PHD domain based on interaction with H3K4me2/3 and controls G1/S transition in conjunction with E2F1, HCF-1 and Set1A, at least in part, by removing the repressive H4K20me1 mark from a subset of E2F1-regulated gene promoters. Phosphorylation-dependent PHF8 dismissal from chromatin in prophase is apparently required for the accumulation of H4K20me1 during early mitosis, which might represent a component of the Condensin II loading process. Accordingly, the HEAT repeat clusters in two non-SMC Condensin II subunits, N-CAPD3 and N-CAPG2, are capable of recognizing H4K20me1, and ChIP-seq. analysis demonstrate a significant overlap of Condensin II and H4K20me1 sites in mitotic HeLa cells. Thus, the identification and characterization of an H4K20me1 demethylase, PHF8, has revealed an intimate link between this enzyme and two distinct events in cell cycle progression. unsynchronized HeLa cells were used to profile H3K4me2 and E2F1; unsynchronized or G1 or G1/S synchronized HeLa cells were used to profile PHF8; M phase synchronized HeLa cells were used to profile SMC4 and H4K20me1