The Experts below are selected from a list of 7734 Experts worldwide ranked by ideXlab platform
Zihua Gong - One of the best experts on this subject based on the ideXlab platform.
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ck2 kinase mediated phf8 phosphorylation controls topbp1 stability to regulate dna replication
Nucleic Acids Research, 2020Co-Authors: Haihua Feng, Zihua Gong, Xiaotian Song, Angkana Thongkum, Fan Zhang, Lihong Lou, Ofer Reizes, Alexandru AlmasanAbstract:ATR functions as a master regulator of the DNA-damage response. ATR activation requires the ATR activator, topoisomerase IIβ-binding protein 1 (TopBP1). However, the underlying mechanism of TopBP1 regulation and how its regulation affects DNA replication remain unknown. Here, we report a specific interaction between TopBP1 and the histone demethylase PHF8. The TopBP1/PHF8 interaction is mediated by the BRCT 7+8 domain of TopBP1 and phosphorylation of PHF8 at Ser854. This interaction is cell-cycle regulated and phosphorylation-dependent. PHF8 is phosphorylated by CK2, which regulates binding of PHF8 to TopBP1. Importantly, PHF8 regulates TopBP1 protein level by preventing its ubiquitination and degradation mediated by the E3 ligase UBR5. Interestingly, PHF8pS854 is likely to contribute to regulation of TopBP1 stability and DNA replication checkpoint. Further, both TopBP1 and PHF8 are required for efficient replication fork restart. Together, these data identify PHF8 as a TopBP1-binding protein and provide mechanistic insight into how PHF8 regulates TopBP1 stability to maintain DNA replication.
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PHF6 regulates cell cycle progression by suppressing ribosomal rna synthesis
Epigenetics & Chromatin, 2013Co-Authors: Jiadong Wang, Justin W C Leung, Zihua Gong, Lin FengAbstract:Mutation of PHF6, which results in X-linked mental retardation disorder-Borjeson-Forssman-Lehmann syndrome, is also present in about 38% of adult T-cell acute lymphoblastic leukemias and 3% of adult acute myeloid leukemias. However, it remains to be determined exactly how PHF6 acts in vivo and what functions of PHF6 may be associated with its putative tumor suppressor function. Here, we demonstrate that PHF6 is a nucleolus, ribosomal RNA promoter-associated protein. PHF6 directly interacts with UBF through its PHD1 domain and suppresses rRNA transcription by affecting the protein level of UBF. Knockdown of PHF6 impairs cell proliferation and arrests cells at G2/M phase, which is accompanied by increased level of phosphorylated H2AX (γ-H2AX), indicating that PHF6 deficiency leads to the accumulation of DNA damage in the cell. We found that increased DNA damage occurs at rDNA locus in PHF6-deficient cells. This effect could be reversed by knocking-down UBF or over-expressing RNASE1, which removes RNA:DNA hybrids, suggesting that there is a functional link between rRNA synthesis and genomic stability at rDNA locus. Together, these results reveal that the key function of PHF6 is involved in regulating rRNA synthesis, which may contribute to its roles in cell cycle control, genomic maintenance and tumor suppression.
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PHF6 regulates cell cycle progression by suppressing ribosomal rna synthesis
Journal of Biological Chemistry, 2013Co-Authors: Jiadong Wang, Justin W C Leung, Zihua Gong, Lin FengAbstract:Mutation of PHF6, which results in the X-linked mental retardation disorder Borjeson-Forssman-Lehmann syndrome, is also present in about 38% of adult T-cell acute lymphoblastic leukemias and 3% of adult acute myeloid leukemias. However, it remains to be determined exactly how PHF6 acts in vivo and what functions of PHF6 may be associated with its putative tumor suppressor function. Here, we demonstrate that PHF6 is a nucleolus, ribosomal RNA promoter-associated protein. PHF6 directly interacts with upstream binding factor (UBF) through its PHD1 domain and suppresses ribosomal RNA (rRNA) transcription by affecting the protein level of UBF. Knockdown of PHF6 impairs cell proliferation and arrests cells at G2/M phase, which is accompanied by an increased level of phosphorylated H2AX, indicating that PHF6 deficiency leads to the accumulation of DNA damage in the cell. We found that increased DNA damage occurs at the ribosomal DNA (rDNA) locus in PHF6-deficient cells. This effect could be reversed by knocking down UBF or overexpressing RNASE1, which removes RNA-DNA hybrids, suggesting that there is a functional link between rRNA synthesis and genomic stability at the rDNA locus. Together, these results reveal that the key function of PHF6 is involved in regulating rRNA synthesis, which may contribute to its roles in cell cycle control, genomic maintenance, and tumor suppression.
Wenching Wang - One of the best experts on this subject based on the ideXlab platform.
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targeting the histone demethylase phf8 mediated pkcα src pten axis in her2 negative gastric cancer
Proceedings of the National Academy of Sciences of the United States of America, 2020Co-Authors: Linlu Tseng, Hsinhung Cheng, Tasen Yeh, Shihchiang Huang, Yayun Syu, Chihpin Chuu, Chiouhwa Yuh, Hsing Jien Kung, Wenching WangAbstract:Targeted treatments for advanced gastric cancer (GC) are needed, particularly for HER2-negative GC, which represents the majority of cases (80 to 88%). In this study, in silico analyses of the lysine histone demethylases (KDMs) involved in diverse biological processes and diseases revealed that PHD finger protein 8 (PHF8, KDM7B) was significantly associated with poor clinical outcome in HER2-negative GC. The depletion of PHF8 significantly reduced cancer progression in GC cells and in mouse xenografts. PHF8 regulated genes involved in cell migration/motility based on a microarray analysis. Of note, PHF8 interacted with c-Jun on the promoter of PRKCA which encodes PKCα. The depletion of PHF8 or PKCα greatly up-regulated PTEN expression, which could be rescued by ectopic expression of a PKCα expression vector or an active Src. These suggest that PTEN destabilization occurs mainly via the PKCα-Src axis. GC cells treated with midostaurin or bosutinib significantly suppressed migration in vitro and in zebrafish models. Immunohistochemical analyses of PHF8, PKCα, and PTEN showed a positive correlation between PHF8 and PKCα but negative correlations between PHF8 and PTEN and between PKCα and PTEN. Moreover, high PHF8-PKCα expression was significantly correlated with worse prognosis. Together, our results suggest that the PKCα-Src-PTEN pathway regulated by PHF8/c-Jun is a potential prognostic/therapeutic target in HER2-negative advanced GC.
Hsing Jien Kung - One of the best experts on this subject based on the ideXlab platform.
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targeting the histone demethylase phf8 mediated pkcα src pten axis in her2 negative gastric cancer
Proceedings of the National Academy of Sciences of the United States of America, 2020Co-Authors: Linlu Tseng, Hsinhung Cheng, Tasen Yeh, Shihchiang Huang, Yayun Syu, Chihpin Chuu, Chiouhwa Yuh, Hsing Jien Kung, Wenching WangAbstract:Targeted treatments for advanced gastric cancer (GC) are needed, particularly for HER2-negative GC, which represents the majority of cases (80 to 88%). In this study, in silico analyses of the lysine histone demethylases (KDMs) involved in diverse biological processes and diseases revealed that PHD finger protein 8 (PHF8, KDM7B) was significantly associated with poor clinical outcome in HER2-negative GC. The depletion of PHF8 significantly reduced cancer progression in GC cells and in mouse xenografts. PHF8 regulated genes involved in cell migration/motility based on a microarray analysis. Of note, PHF8 interacted with c-Jun on the promoter of PRKCA which encodes PKCα. The depletion of PHF8 or PKCα greatly up-regulated PTEN expression, which could be rescued by ectopic expression of a PKCα expression vector or an active Src. These suggest that PTEN destabilization occurs mainly via the PKCα-Src axis. GC cells treated with midostaurin or bosutinib significantly suppressed migration in vitro and in zebrafish models. Immunohistochemical analyses of PHF8, PKCα, and PTEN showed a positive correlation between PHF8 and PKCα but negative correlations between PHF8 and PTEN and between PKCα and PTEN. Moreover, high PHF8-PKCα expression was significantly correlated with worse prognosis. Together, our results suggest that the PKCα-Src-PTEN pathway regulated by PHF8/c-Jun is a potential prognostic/therapeutic target in HER2-negative advanced GC.
Lin Feng - One of the best experts on this subject based on the ideXlab platform.
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PHF6 regulates cell cycle progression by suppressing ribosomal rna synthesis
Epigenetics & Chromatin, 2013Co-Authors: Jiadong Wang, Justin W C Leung, Zihua Gong, Lin FengAbstract:Mutation of PHF6, which results in X-linked mental retardation disorder-Borjeson-Forssman-Lehmann syndrome, is also present in about 38% of adult T-cell acute lymphoblastic leukemias and 3% of adult acute myeloid leukemias. However, it remains to be determined exactly how PHF6 acts in vivo and what functions of PHF6 may be associated with its putative tumor suppressor function. Here, we demonstrate that PHF6 is a nucleolus, ribosomal RNA promoter-associated protein. PHF6 directly interacts with UBF through its PHD1 domain and suppresses rRNA transcription by affecting the protein level of UBF. Knockdown of PHF6 impairs cell proliferation and arrests cells at G2/M phase, which is accompanied by increased level of phosphorylated H2AX (γ-H2AX), indicating that PHF6 deficiency leads to the accumulation of DNA damage in the cell. We found that increased DNA damage occurs at rDNA locus in PHF6-deficient cells. This effect could be reversed by knocking-down UBF or over-expressing RNASE1, which removes RNA:DNA hybrids, suggesting that there is a functional link between rRNA synthesis and genomic stability at rDNA locus. Together, these results reveal that the key function of PHF6 is involved in regulating rRNA synthesis, which may contribute to its roles in cell cycle control, genomic maintenance and tumor suppression.
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PHF6 regulates cell cycle progression by suppressing ribosomal rna synthesis
Journal of Biological Chemistry, 2013Co-Authors: Jiadong Wang, Justin W C Leung, Zihua Gong, Lin FengAbstract:Mutation of PHF6, which results in the X-linked mental retardation disorder Borjeson-Forssman-Lehmann syndrome, is also present in about 38% of adult T-cell acute lymphoblastic leukemias and 3% of adult acute myeloid leukemias. However, it remains to be determined exactly how PHF6 acts in vivo and what functions of PHF6 may be associated with its putative tumor suppressor function. Here, we demonstrate that PHF6 is a nucleolus, ribosomal RNA promoter-associated protein. PHF6 directly interacts with upstream binding factor (UBF) through its PHD1 domain and suppresses ribosomal RNA (rRNA) transcription by affecting the protein level of UBF. Knockdown of PHF6 impairs cell proliferation and arrests cells at G2/M phase, which is accompanied by an increased level of phosphorylated H2AX, indicating that PHF6 deficiency leads to the accumulation of DNA damage in the cell. We found that increased DNA damage occurs at the ribosomal DNA (rDNA) locus in PHF6-deficient cells. This effect could be reversed by knocking down UBF or overexpressing RNASE1, which removes RNA-DNA hybrids, suggesting that there is a functional link between rRNA synthesis and genomic stability at the rDNA locus. Together, these results reveal that the key function of PHF6 is involved in regulating rRNA synthesis, which may contribute to its roles in cell cycle control, genomic maintenance, and tumor suppression.
Jiemin Wong - One of the best experts on this subject based on the ideXlab platform.
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phd finger protein 2 phf2 represses ribosomal rna gene transcription by antagonizing phf finger protein 8 phf8 and recruiting methyltransferase suv39h1
Journal of Biological Chemistry, 2014Co-Authors: Meng Wu, Lan Fang, Fang Yu, Shimeng Cheng, Jiwen Li, James X Du, Jiemin WongAbstract:Regulation of rDNA transcription is central to cell growth and proliferation. PHF2 and PHF8 belong to a subfamily of histone demethylases that also possess a PHD domain-dependent di-/trimethylated histone 3 lysine 4 (H3K4me2/3) binding activity and are known to be enriched in the nucleolus. In this study, we show that, unlike PHF8 that activates rDNA transcription, PHF2 inhibits rDNA transcription. Depletion of PHF2 by RNA interference increases and overexpression of PHF2 decreases rDNA transcription, respectively, whereas simultaneous depletion of PHF8 and PHF2 restores the level of rDNA transcription. The inhibition of rDNA transcription by PHF2 depends on its H3K4me2/3 binding activity that is also required for PHF2 association with the promoter of rDNA genes but not its demethylase activity. We provide evidence that PHF2 is likely to repress rDNA transcription by competing with PHF8 for binding of rDNA promoter and by recruiting H3K9me2/3 methyltransferase SUV39H1. We also provide evidence that, whereas PHF8 promotes, PHF2 represses the transcriptional activity of RARα, Oct4, and KLF4 and a few PHF8 target genes tested. Taken together, our study demonstrates a repressive role for PHF2 in transcription by RNA polymerase I and II.
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the x linked mental retardation gene phf8 is a histone demethylase involved in neuronal differentiation
Cell Research, 2010Co-Authors: Jihui Qiu, Guang Shi, Yuanhui Jia, Shuo Dong, Jiemin WongAbstract:Recent studies have identified mutations in PHF8, an X-linked gene encoding a JmjC domain-containing protein, as a causal factor for X-linked mental retardation (XLMR) and cleft lip/cleft palate. However, the underlying mechanism is unknown. Here we show that PHF8 is a histone demethylase and coactivator for retinoic acid receptor (RAR). Although activities for both H3K4me3/2/1 and H3K9me2/1 demethylation were detected in cellular-based assays, recombinant PHF8 exhibited only H3K9me2/1 demethylase activity in vitro, suggesting that PHF8 is an H3K9me2/1 demethylase whose specificity may be modulated in vivo. Importantly, a mutant PHF8 (phenylalanine at position 279 to serine) identified in the XLMR patients is defective in enzymatic activity, indicating that the loss of histone demethylase activity is causally linked with the onset of disease. In addition, we show that PHF8 binds specifically to H3K4me3/2 peptides via an N-terminal PHD finger domain. Consistent with a role for PHF8 in neuronal differentiation, knockdown of PHF8 in mouse embryonic carcinoma P19 cells impairs RA-induced neuronal differentiation, whereas overexpression of the wild-type but not the F279S mutant PHF8 drives P19 cells toward neuronal differentiation. Furthermore, we show that PHF8 interacts with RARalpha and functions as a coactivator for RARalpha. Taken together, our results suggest that histone methylation modulated by PHF8 plays a critical role in neuronal differentiation.