1
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Lee KH, Park JW, Sung HS, Choi YJ, Kim WH, Lee HS, Chung HJ, Shin HW, Cho CH, Kim TY, Li SH, Youn HD, Kim SJ, Chun YS. PHF2 histone demethylase acts as a tumor suppressor in association with p53 in cancer. Oncogene 2014; 34:2897-909. [PMID: 25043306 DOI: 10.1038/onc.2014.219] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 05/05/2014] [Accepted: 06/15/2014] [Indexed: 12/14/2022]
Abstract
Plant homeodomain finger 2 (PHF2) has a role in epigenetic regulation of gene expression by demethylating H3K9-Me2. Several genome-wide studies have demonstrated that the chromosomal region including the PHF2 gene is often deleted in some cancers including colorectal cancer, and this finding encouraged us to investigate the tumor suppressive role of PHF2. As p53 is a critical tumor suppressor in colon cancer, we tested the possibility that PHF2 is an epigenetic regulator of p53. PHF2 was associated with p53, and thereby, promoted p53-driven gene expression in cancer cells under genotoxic stress. PHF2 converted the chromatin that is favorable for transcription by demethylating the repressive H3K9-Me2 mark. In an HCT116 xenograft model, PHF2 was found to be required for the anticancer effects of oxaliplatin and doxorubicin. In PHF2-deficient xenografts, p53 expression was profoundly induced by both drugs, but its downstream product p21 was not, suggesting that p53 cannot be activated in the absence of PHF2. To find clinical evidence about the role of PHF2, we analyzed the expressions of PHF2, p53 and p21 in human colon cancer tissues and adjacent normal tissues from patients. PHF2 was downregulated in cancer tissues and PHF2 correlated with p21 in cancers expressing functional p53. Colon and stomach cancer tissue arrays showed a positive correlation between PHF2 and p21 expressions. Informatics analyses using the Oncomine database also supported our notion that PHF2 is downregulated in colon and stomach cancers. On the basis of these findings, we propose that PHF2 acts as a tumor suppressor in association with p53 in cancer development and ensures p53-mediated cell death in response to chemotherapy.
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Affiliation(s)
- K-H Lee
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - J-W Park
- 1] Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea [2] Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - H-S Sung
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Y-J Choi
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - W H Kim
- Department of Pathology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - H S Lee
- Department of Pathology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - H-J Chung
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - H-W Shin
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - C-H Cho
- 1] Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea [2] Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - T-Y Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - S-H Li
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - H-D Youn
- 1] Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea [2] Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - S J Kim
- 1] Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea [2] Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea [3] Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Y-S Chun
- 1] Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Republic of Korea [2] Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea [3] Department of Physiology, Seoul National University College of Medicine, Seoul, Republic of Korea
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2
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Choi HH, Choi HK, Jung SY, Hyle J, Kim BJ, Yoon K, Cho EJ, Youn HD, Lahti JM, Qin J, Kim ST. CHK2 kinase promotes pre-mRNA splicing via phosphorylating CDK11(p110). Oncogene 2012. [PMID: 23178491 DOI: 10.1038/onc.2012.535] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Checkpoint kinase 2 (CHK2) kinase is a key mediator in many cellular responses to genotoxic stresses, including ionizing radiation (IR) and topoisomerase inhibitors. Upon IR, CHK2 is activated by ataxia telangiectasia mutated kinase and regulates the S-phase and G1-S checkpoints, apoptosis and DNA repair by phosphorylating downstream target proteins, such as p53 and Brca1. In addition, CHK2 is thought to be a multi-organ cancer susceptibility gene. In this study, we used a tandem affinity purification strategy to identify proteins that interact with CHK2 kinase. Cyclin-dependent kinase 11 (CDK11)(p110) kinase, implicated in pre-mRNA splicing and transcription, was identified as a CHK2-interacting protein. CHK2 kinase phosphorylated CDK11(p110) on serine 737 in vitro. Unexpectedly, CHK2 kinase constitutively phosphorylated CDK11(p110) in a DNA damage-independent manner. At a molecular level, CDK11(p110) phosphorylation was required for homodimerization without affecting its kinase activity. Overexpression of CHK2 promoted pre-mRNA splicing. Conversely, CHK2 depletion decreased endogenous splicing activity. Mutation of the phosphorylation site in CDK11(p110) to alanine abrogated its splicing-activating activity. These results provide the first evidence that CHK2 kinase promotes pre-mRNA splicing via phosphorylating CDK11(p110).
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Affiliation(s)
- H-H Choi
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Samsung Biomedical Research Institute, Suwon, Republic of Korea
| | - H-K Choi
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Samsung Biomedical Research Institute, Suwon, Republic of Korea
| | - S Y Jung
- Center for Molecular Discovery, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, USA
| | - J Hyle
- Department of Genetics and Tumor Cell Biology, St Jude Children's Research Hospital, Memphis, TN, USA
| | - B-J Kim
- Center for Molecular Discovery, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, USA
| | - K Yoon
- School of Life Science and Biotechnology, Sungkyunkwan University, Suwon, Republic of Korea
| | - E-J Cho
- School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - H-D Youn
- National Research Laboratory for Metabolic Checkpoint, Departments of Biomedical Sciences and Biochemistry and Molecular Biology, Cancer Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - J M Lahti
- Department of Genetics and Tumor Cell Biology, St Jude Children's Research Hospital, Memphis, TN, USA
| | - J Qin
- Center for Molecular Discovery, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, USA
| | - S-T Kim
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Samsung Biomedical Research Institute, Suwon, Republic of Korea
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3
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Abstract
Germline mutations in the von Hippel-Lindau (VHL) tumor suppressor gene cause VHL disease, a rare and autosomal-dominant genetic syndrome. Because VHL protein (pVHL) is the master regulator of hypoxia-inducible factor alpha (HIFα), the most prominent feature of VHL disease is the deregulation of HIFα proteins. However, the precise mechanism by which the loss of pVHL function contributes to tumorigenesis is not fully understood. Here, we show that pVHL destabilizes the F-box protein Skp2, a chief component of Skp, Cullin, F-box-containing complex that promotes DNA synthesis in the S phase. The β-domain of pVHL interacts with Skp2, stimulating proteasome-dependent Skp2 degradation, but the destabilization of Skp2 does not depend on the E3 ubiquitin ligase activity of pVHL. Notably, the generation of DNA damage induces Skp2 degradation, which is attenuated by the suppression of endogenous pVHL expression. One possible mechanism of pVHL-dependent Skp2 degradation entails the antagonizing of Akt-mediated Skp2 phosphorylation, which maintains Skp2 stability. Reintroduction of VHL into VHL-null renal cell carcinoma (RCC) cells decreased Skp2 levels and restored DNA damage-dependent Skp2 degradation. These results identify the tumor suppressor function of pVHL in delaying the S-phase progression to inhibit cell proliferation on DNA damage. Clinically, this report explains as to why Skp2 accumulates abnormally in RCC tissues.
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Affiliation(s)
- J-S Roe
- National Research Laboratory for Metabolic Checkpoint, Departments of Biomedical Sciences and Biochemistry and Molecular Biology, Cancer Research Institute, Seoul National University College of Medicine, Republic of Korea
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4
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Cho IR, Koh SS, Min HJ, Park EH, Ratakorn S, Jhun BH, Jeong SH, Yoo YH, Youn HD, Johnston RN, Chung YH. Down-regulation of HIF-1α by oncolytic reovirus infection independently of VHL and p53. Cancer Gene Ther 2010; 17:365-72. [DOI: 10.1038/cgt.2009.84] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Lee SM, Kim JH, Cho EJ, Youn HD. A nucleocytoplasmic malate dehydrogenase regulates p53 transcriptional activity in response to metabolic stress. Cell Death Differ 2009; 16:738-48. [DOI: 10.1038/cdd.2009.5] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
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Zhang LH, Youn HD, Liu JO. Inhibition of cell cycle progression by the novel cyclophilin ligand sanglifehrin A is mediated through the NFkappa B-dependent activation of p53. J Biol Chem 2001; 276:43534-40. [PMID: 11557753 DOI: 10.1074/jbc.m104257200] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sanglifehrin A belongs to a novel family of immunophilin-binding ligands. Sanglifehrin A is similar to cyclosporin A in that it binds to cyclophilins. Unlike cyclosporin A, however, the cyclophilin-sanglifehrin A complex has no effect on the calcium-dependent protein phosphatase calcineurin. It has been previously shown that sanglifehrin A specifically blocks T cell proliferation in response to interleukin 2 by inhibiting the appearance of cell cycle kinase activity cyclinE-Cdk2. How sanglifehrin A treatment leads to the cell cycle blockade has remained unknown. We report that sanglifehrin A is capable of activating the tumor suppressor gene p53 at the transcription level, leading to up-regulation of p21 that then binds and inhibits the cylcinE-Cdk2 complex. Further analysis of different elements in the p53 promoter showed that sanglifehrin A activates p53 transcription primarily through the activation of the transcription factor NFkappaB by activating IkappaB kinase in a manner that is similar to several genotoxic agents. Unlike other genotoxic drugs, sanglifehrin A does not cause DNA damage, making it a unique natural product that is capable of activating the NFkappaB signaling pathway without affecting DNA.
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Affiliation(s)
- L H Zhang
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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7
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Esau C, Boes M, Youn HD, Tatterson L, Liu JO, Chen J. Deletion of calcineurin and myocyte enhancer factor 2 (MEF2) binding domain of Cabin1 results in enhanced cytokine gene expression in T cells. J Exp Med 2001; 194:1449-59. [PMID: 11714752 PMCID: PMC2193671 DOI: 10.1084/jem.194.10.1449] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Cabin1 binds calcineurin and myocyte enhancer factor 2 (MEF2) through its COOH-terminal region. In cell lines, these interactions were shown to inhibit calcineurin activity after T cell receptor (TCR) signaling and transcriptional activation of Nur77 by MEF2. The role of these interactions under physiological conditions was investigated using a mutant mouse strain that expresses a truncated Cabin1 lacking the COOH-terminal calcineurin and MEF2 binding domains. T and B cell development and thymocyte apoptosis were normal in mutant mice. In response to anti-CD3 stimulation, however, mutant T cells expressed significantly higher levels of interleukin (IL)-2, IL-4, IL-9, IL-13, and interferon gamma than wild-type T cells. The enhanced cytokine gene expression was not associated with change in nuclear factor of activated T cells (NF-AT)c or NF-ATp nuclear translocation but was preceded by the induction of a phosphorylated form of MEF2D in mutant T cells. Consistent with the enhanced cytokine expression, mutant mice had elevated levels of serum immunoglobulin (Ig)G1, IgG2b, and IgE and produced more IgG1 in response to a T cell-dependent antigen. These findings suggest that the calcineurin and MEF2 binding domain of Cabin1 is dispensable for thymocyte development and apoptosis, but is required for proper regulation of T cell cytokine expression probably through modulation of MEF2 activity.
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Affiliation(s)
- C Esau
- Center for Cancer Research and Department of Biology, Massachusetts Institute of Technology, 40 Ames St., Cambridge, MA 02139, USA
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8
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Abstract
Thapsigargin (TG), which inhibits endoplasmic reticulum-dependent Ca(2 +)-ATPase and thereby increases cytosolic Ca(2 +), has been reported to cause apoptosis in T lymphocytes another cell types. In this study, we investigated the molecular mechanisms that are involved in the apoptosis induced by TG in T cell hybridomas. Exposure to TG results in rapid induction of the orphan steroid receptor, Nur77, accompanied by apoptosis of T cell hybridomas. The expression of Nur77 in response to TG treatment is sensitive to cyclosporin A, implicating that activation of calcineurin is necessary for Nur77 expression. The TG-induced Nur77 expression is also inhibited by overexpression of Cabin1, an endogenous inhibitor of calcineurin and a corepressor of the transcription factor MEF2, suggesting that MEF2 activation is required for Nur77 expression. These results suggest that induction of Nur77 expression and apoptosis by TG are mediated by the same signaling pathways that are involved in T cell receptor-mediated thymocyte apoptosis, including the calcineurin pathway and Cabin1-MEF2 pathway.
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Affiliation(s)
- W Liu
- Center for Cancer Research, Departments of Biology and Chemistry, Massachusetts Institute of Technology, Cambridge 02139, USA
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9
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Abstract
Thapsigargin (TG), which inhibits endoplasmic reticulum-dependent Ca(2 +)-ATPase and thereby increases cytosolic Ca(2 +), has been reported to cause apoptosis in T lymphocytes another cell types. In this study, we investigated the molecular mechanisms that are involved in the apoptosis induced by TG in T cell hybridomas. Exposure to TG results in rapid induction of the orphan steroid receptor, Nur77, accompanied by apoptosis of T cell hybridomas. The expression of Nur77 in response to TG treatment is sensitive to cyclosporin A, implicating that activation of calcineurin is necessary for Nur77 expression. The TG-induced Nur77 expression is also inhibited by overexpression of Cabin1, an endogenous inhibitor of calcineurin and a corepressor of the transcription factor MEF2, suggesting that MEF2 activation is required for Nur77 expression. These results suggest that induction of Nur77 expression and apoptosis by TG are mediated by the same signaling pathways that are involved in T cell receptor-mediated thymocyte apoptosis, including the calcineurin pathway and Cabin1-MEF2 pathway.
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Affiliation(s)
- W Liu
- Center for Cancer Research, Departments of Biology and Chemistry, Massachusetts Institute of Technology, Cambridge 02139, USA
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10
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Abstract
Nuclear factor of activated T cells (NFAT) plays a key role in T cell activation. The activation of NFAT involves calcium- and calcineurin-dependent dephosphorylation and nuclear translocation from the cytoplasm, a process that is opposed by protein kinases. We show here that the peptidyl prolyl cis-trans isomerase Pin1 interacts specifically with the phosphorylated form of NFAT. The NFAT-Pin1 interaction is mediated through the WW domain of Pin1 and the serine-proline-rich domains of NFAT. Furthermore, binding of Pin1 to NFAT inhibits the calcineurin-mediated dephosphorylation of NFAT in vitro, and overexpression of Pin1 in T cells inhibits calcium-dependent activation of NFAT in vivo. These results suggest a possible role for Pin1 in the regulation of NFAT in T cells.
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Affiliation(s)
- W Liu
- Center for Cancer Research, Departments of Biology and Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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11
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Youn HD, Chatila TA, Liu JO. Integration of calcineurin and MEF2 signals by the coactivator p300 during T-cell apoptosis. EMBO J 2000; 19:4323-31. [PMID: 10944115 PMCID: PMC302027 DOI: 10.1093/emboj/19.16.4323] [Citation(s) in RCA: 181] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2000] [Revised: 06/23/2000] [Accepted: 06/23/2000] [Indexed: 02/03/2023] Open
Abstract
T-cell antigen receptor (TCR)-induced thymocyte apoptosis is mediated by calcium-dependent signal transduction pathways leading to the transcriptional activation of members of the Nur77 family. The major calcium- and calcineurin-responsive elements in the Nur77 promoter are binding sites for myocyte enhancer factor-2 (MEF2). It has been shown that nuclear factor of activated T cells (NFAT) interacts with MEF2D and enhances its transcriptional activity, offering a plausible mechanism of activation of MEF2D by calcineurin. We report here that NFATp synergizes with MEF2D to recruit the coactivator p300 for the transcription of Nur77. Surprisingly, the enhancement of transcriptional activity of MEF2D by NFATp does not require its DNA-binding activity, suggesting that NFATp acts as a coactivator for MEF2D. Transient co-expression of p300, MEF2D, NFATp and constitutively active calcineurin is sufficient to recapitulate TCR signaling for the selective induction of the endogenous Nur77 gene. These results implicate NFAT as an important mediator of T-cell apoptosis and suggest that NFAT is capable of integrating the calcineurin signaling pathway and other pathways through direct protein-protein interaction with other transcription factors.
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MESH Headings
- Apoptosis
- Base Sequence
- Binding Sites
- Calcineurin/chemistry
- Calcineurin/metabolism
- Calcium/metabolism
- Cell Line
- Cell Nucleus/metabolism
- Cyclosporine/pharmacology
- DNA/metabolism
- DNA-Binding Proteins/chemistry
- DNA-Binding Proteins/metabolism
- Enzyme Inhibitors/pharmacology
- Gene Expression Regulation
- Genes, Reporter
- Humans
- Immunosuppressive Agents/pharmacology
- Interleukin-2/metabolism
- Ionomycin/pharmacology
- Ionophores/pharmacology
- Jurkat Cells
- MADS Domain Proteins
- MEF2 Transcription Factors
- Models, Biological
- Molecular Sequence Data
- Myogenic Regulatory Factors
- NFATC Transcription Factors
- Nuclear Proteins/chemistry
- Nuclear Proteins/metabolism
- Nuclear Receptor Subfamily 4, Group A, Member 1
- Plasmids/metabolism
- Promoter Regions, Genetic
- Protein Binding
- Protein Biosynthesis
- Protein Structure, Tertiary
- Receptors, Cytoplasmic and Nuclear
- Receptors, Steroid
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Homology, Nucleic Acid
- Signal Transduction
- Sirolimus/pharmacology
- T-Lymphocytes/metabolism
- T-Lymphocytes/pathology
- Tacrolimus/pharmacology
- Trans-Activators/chemistry
- Trans-Activators/metabolism
- Transcription Factors/chemistry
- Transcription Factors/metabolism
- Transcription, Genetic
- Transfection
- Tumor Cells, Cultured
- beta-Galactosidase/metabolism
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Affiliation(s)
- H D Youn
- Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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12
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Abstract
The myocyte enhancer factor 2 (MEF2) consists of a family of transcription factors that play important roles in a number of physiological processes from muscle cell differentiation to neuronal survival and T cell apoptosis. MEF2 has been reported to be associated with several distinct repressors including Cabin1(cain), MEF2-interacting transcriptional repressor (MITR), and HDAC4. It has been previously shown that Cabin1 is associated with MEF2 in a calcium-sensitive manner; activated calmodulin binds to Cabin1 and releases it from MEF2. However, it was not known whether the binding of HDAC4 and MITR to MEF2 is also regulated by calcium. We report that HDAC4 and MITR contain calmodulin-binding domains that overlap with their MEF2-binding domains. Binding of calmodulin to HDAC4 leads to its dissociation from MEF2, relieving MEF2 from the transcriptional repression by HDAC4. Together, HDAC4, MITR, and Cabin1 constitute a family of calcium-sensitive transcriptional repressors of MEF2.
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Affiliation(s)
- H D Youn
- Center for Cancer Research, Department of Chemistry and Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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13
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Youn HD, Liu JO. Cabin1 represses MEF2-dependent Nur77 expression and T cell apoptosis by controlling association of histone deacetylases and acetylases with MEF2. Immunity 2000; 13:85-94. [PMID: 10933397 DOI: 10.1016/s1074-7613(00)00010-8] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
TCR signaling leading to thymocyte apoptosis is mediated through the expression of the Nur77 family of orphan nuclear receptors. MEF2 has been shown to be the major transcription factor responsible for calcium-dependent Nur77 transcription. Cabin1 was recently identified as a transcriptional repressor of MEF2, which can be released from MEF2 in a calcium-dependent fashion. The molecular basis of repression of MEF2 by Cabin1, however, has remained unknown. We report that Cabin1 represses MEF2 by two distinct mechanisms. Cabin1 recruits mSin3 and its associated histone deacetylases 1 and 2; Cabin1 also competes with p300 for binding to MEF2. Thus, activation of MEF2 and the consequent transcription of Nur77 are controlled by the association of MEF2 with the histone deacetylases via the calcium-dependent repressor Cabin1.
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Affiliation(s)
- H D Youn
- Center for Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA
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14
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Abstract
T cell receptor (TCR)-induced apoptosis of thymocytes is mediated by calcium-dependent expression of the steroid receptors Nur77 and Nor1. Nur77 expression is controlled by the transcription factor myocyte enhancer factor 2 (MEF2), but how MEF2 is activated by calcium signaling is still obscure. Cabin1, a calcineurin inhibitor, was found to regulate MEF2. MEF2 was normally sequestered by Cabin1 in a transcriptionally inactive state. TCR engagement led to an increase in intracellular calcium concentration and the dissociation of MEF2 from Cabin1, as a result of competitive binding of activated calmodulin to Cabin1. The interplay between Cabin1, MEF2, and calmodulin defines a distinct signaling pathway from the TCR to the Nur77 promoter during T cell apoptosis.
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Affiliation(s)
- H D Youn
- Center for Cancer Research, Department of Biology, Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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15
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Youn H, Kwak J, Youn HD, Hah YC, Kang SO. Lipoamide dehydrogenase from streptomyces seoulensis: biochemical and genetic properties. Biochim Biophys Acta 1998; 1388:405-18. [PMID: 9858775 DOI: 10.1016/s0167-4838(98)00200-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Lipoamide dehydrogenase was purified around 22-fold relative to the crude extracts of Streptomyces seoulensis with an overall yield of 9. 5%. The enzyme was composed of two identical subunits with a molecular mass of 54 kDa and contained 1 mol of FAD per mol of subunit. The absorption spectra of the enzyme revealed the absorption maxima of flavoprotein at 272, 349, and 457 nm. Catalytically active two-electron reduced lipoamide dehydrogenase was produced by anaerobic reduction with one equivalent of NADH. Addition of excess amount of NADH led to the four-electron reduced lipoamide dehydrogenase. The reaction of the enzyme in the reduction reaction of lipoamide or lipoic acid could be explained by a ping-pong mechanism like many other lipoamide dehydrogenases reported earlier. The enzyme also catalysed the reduction of various quinone compounds with NADH as electron donor via a ping-pong mechanism. The enzyme can catalyse a single electron transfer in case of quinone-reducing process, evidenced by the production of 1, 4-naphthosemiquinone radical anion. The quinone-reducing activity of the enzyme was dramatically inhibited by NAD+, indicating the involvement of four-electron reduced form. The structural gene for the enzyme was cloned using a DNA fragment PCR-amplified with the primers designed from N-terminal and internal amino acid sequences. The deduced amino acid sequence shared striking similarity with those of lipoamide dehydrogenases from prokaryotes and eukaryotes. The gene was named lpd. All tested Streptomyces contained one homologue of the lpd gene, which is consistent with the fact that most organisms contain only one lipoamide dehydrogenase.
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Affiliation(s)
- H Youn
- Department of Microbiology, College of Natural Sciences, and Research Centre for Molecular Microbiology, Seoul National University, Seoul 151-742, South Korea
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16
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Abstract
Calcineurin plays a pivotal role in the T cell receptor (TCR)-mediated signal transduction pathway and serves as a common target for the immunosuppressants FK506 and cyclosporin A. We report the identification of a novel endogenous calcineurin binding protein named Cabin 1 that inhibits calcineurin-mediated signal transduction. The interaction between Cabin 1 and calcineurin is dependent on PKC activation. Overexpression of Cabin 1 or its N-terminal truncation mutants inhibits the transcriptional activation of calcineurin-responsive elements in the interleukin-2 promoter and blocks dephosphorylation of NF-AT upon T cell activation. These results suggest a negative regulatory role for Cabin 1 in calcineurin signaling and provide a possible mechanism of feedback inhibition of TCR signaling through cross-talk between protein kinases and calcineurin.
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Affiliation(s)
- L Sun
- Center for Cancer Research and Deparmtent of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA
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17
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Matsugo S, Yan LJ, Konishi T, Youn HD, Lodge JK, Ulrich H, Packer L. The lipoic acid analogue 1,2-diselenolane-3-pentanoic acid protects human low density lipoprotein against oxidative modification mediated by copper ion. Biochem Biophys Res Commun 1997; 240:819-24. [PMID: 9398652 DOI: 10.1006/bbrc.1997.7711] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
1,2-Diselenolane-3-pentanoic acid, in which the sulfur atoms of alpha-lipoic acid are replaced with selenium, displayed markedly different antioxidant properties when compared to alpha-lipoic acid. 1,2-Diselenolane-3-pentanoic acid was unable to inhibit protein oxidative modification of human low density lipoprotein (LDL) and bovine serum albumin induced by copper ion or hydroxyl radical, whereas alpha-lipoic acid showed significant protection. However, 1,2-diselenolane-3-pentanoic acid was able to inhibit the formation of lipid peroxidation products in LDL after oxidation by copper, while alpha-lipoic acid did not. Hence the diselenium compound exerts its effects in a lipophilic environment whilst lipoic acid exerts its effects in a hydrophilic environment. These differences in antioxidant activities of the two compounds may be explained, at least in part, by their differing partition coefficients.
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Affiliation(s)
- S Matsugo
- Department of Molecular and Cell Biology, University of California at Berkeley 94720-3200, USA
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18
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Abstract
The taxonomic position of an actinomycete strain isolated from Korean soil was examined by a polyphasic approach. The isolate, designated IMSNU-1, was clearly assigned to the genus Streptomyces on the basis of morphological and chemotaxonomic data. The test strain was the subject of a probabilistic identification study using the identification matrices generated by Langham et al. (J. Gen. Microbiol. 135:121-133, 1989) and found to be marginally close to clusters 19 and 39. An almost complete 16S rRNA gene (rDNA) sequence was obtained for the test strain and compared with those of representative streptomycetes. 16S rDNA sequence data not only support the strain's membership in the genus Streptomyces but also provide strong evidence that our isolate is genealogically distant from representatives of clusters 19 and 39, forming a separate phyletic line in a clade encompassed by streptomycetes. It is therefore proposed from the polyphasic evidence that strain IMSNU-1 be classified in the genus Streptomyces as Streptomyces seoulensis sp. nov.
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Affiliation(s)
- J Chun
- Department of Microbiology, College of Natural Sciences, Seoul National University, Republic of Korea
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19
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Abstract
Two unique isozymes of superoxide dismutase (EC 1.15.1.1) were purified to apparent homogeneity from Streptomyces griseus by a purification procedure consisting of ammonium sulfate precipitation and chromatographies on DEAE Sephacel, Sephacryl S-200, and DEAE 5PW. Superoxide dismutase I was composed of four identical subunits of 13.0 kDa. The absorption spectrum of superoxide dismutase I exhibited absorption bands at 276 and 378 nm and a broad shoulder at 530 nm. The g values of electron paramagnetic resonance spectrum of superoxide dismutase I were g1 = 2.304, g2 = 2.248, and g3 = 2.012 and the resonance centered at g3 = 2.012 was split into triplet, indicating nickel-containing superoxide dismutase. Superoxide dismutase I contained 0.89 g-atom of nickel per mole of 13.0-kDa subunit. Superoxide dismutase II was composed of four identical subunits of 22.0 kDa. The absorption spectrum of superoxide dismutase II showed the featureless absorption band in the range of 300-500 nm. The g values of electron paramagnetic resonance spectrum of superoxide dismutase II were gz = 4.762, gx = 4.072, and gy = 3.742, indicating iron-containing superoxide dismutase. Superoxide dismutase II uniquely contains 0.40 g-atom of iron per mole of monomer as well as 0.43 g-atom of zinc per mole of monomer. The immunological cross-reactivity between two isozymes was not found. Nickel-containing superoxide dismutase was widely distributed within the genus Streptomyces; however, iron- and zinc-containing superoxide dismutase was not found in S. albus and S. longisporoflavus, on the basis of the immunological cross-reactivity.
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Affiliation(s)
- H D Youn
- Department of Microbiology, College of Natural Sciences, Seoul National University, Republic of Korea
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20
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Abstract
A novel type of superoxide dismutase (SOD) was purified to apparent homogeneity from the cytosolic fractions of Streptomyces sp. IMSNU-1 and Strep. coelicolor ATCC 10147 respectively. Both enzymes were composed of four identical subunits of 13.4 kDa, were stable at pH 4.0-8.0 and up to 70 degrees C, and were inhibited by cyanide and H2O2 but little inhibited by azide. The atomic absorption analyses revealed that both enzymes contain 0.74 g-atom of nickel per mol of subunit. Both enzymes were different from iron-containing SOD and manganese-containing SOD from Escherichia coli, and copper- and zinc-containing SODs from Saccharomyces cerevisiae and bovine erythrocytes, with respect to amino acid composition, N-terminal amino acid sequence and cross-reactivity against antibody. The absorption spectra of both enzymes were identical, exhibiting maxima at 276 and 378 nm, and a broad peak at 531 nm. The EPR spectra of both enzymes were almost identical with that of NiIII in a tetragonal symmetry of NiIII-oligopeptides especially containing histidine. The apoenzymes, lacking in nickel, had no ability to mediate the conversion of superoxide anion radical to hydrogen peroxide, strongly indicating that NiIII plays a main role in these enzymes.
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Affiliation(s)
- H D Youn
- Department of Microbiology, College of Natural Sciences, Seoul National University, Republic of Korea
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21
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Abstract
The properties of the haem environment of an extracellular peroxidase from Pleurotus ostreatus were studied by electronic absorption spectroscopy. A high-spin ferric form was predominant in the native enzyme and a high-spin ferrous form in the reduced enzyme. Cyanide was readily bound to the haem iron in the native form, thereby changing the enzyme to a low-spin cyano adduct. The electronic absorption spectra of the enzyme were similar to those of lignin peroxidase from Phanerochaete chrysosporium. Compound III of the enzyme was formed after the addition of an excess of H2O2 to the native enzyme, and thereafter spontaneously reverted to the native form. The enzyme oxidized 1-(3,5-dimethoxy-4-hydroxyphenyl)-2-(2-methoxyphenoxy)-1,3-dihydroxyp ropane in the presence of H2O2 to produce 1-(3,5-dimethoxy-4-hydroxyphenyl)-2-(2-methoxyphenoxy)-1-oxo-3-hydroxypr opane , 2,6-dimethoxyhydroquinone, 2-(2-methoxyphenoxy)-3-hydroxypropanal, 2-(2-methoxyphenoxy)-3-hydroxypropanoic acid, 2,6-dimethoxy-1,4-benzoquinone and guaiacol. A similar oxidation pattern was demonstrated with a one-electron oxidant, ammonium cerium(IV)nitrate. Free radicals were detected as intermediates of the enzyme-mediated oxidation of 1-(3,5-dimethoxy-5-hydroxyphenyl)-2-(2-methoxyphenoxy)-1,3-dihydroxyp ropane and acetosyringone. These results can be explained by the mechanisms involving an initial one-electron oxidation of the lignin substructure. This radical may undergo C alpha-C beta cleavage, C alpha-oxidation and alkyl-phenyl cleavage.
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Affiliation(s)
- Y H Han
- Department of Microbiology, College of Natural Sciences, Seoul National University, Republic of Korea
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22
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Abstract
Catalase-peroxidase was purified to near homogeneity from Streptomyces sp. The enzyme was composed of two subunits with a molecular mass of 78 kDa and contained 1.05 mol of protoporphyrin IX/mol of dimeric protein. The absorption and resonance Raman spectra of the native and its cyano-enzyme were closely similar to those of other heme proteins with a histidine as the fifth ligand. However, the peak from tyrosine ring at approximately 1612 cm-1, which is unique in catalases, was not found in resonance Raman spectra of catalase-peroxidase. The electron paramagnetic resonance spectrum of the native enzyme revealed uniquely two sets of rhombic signals, which were converted to a single high spin, hexacoordinate species after the addition of sodium formate. Cyanide bound to the sixth coordination position of the heme iron, thereby converting the enzyme to a low spin, hexacoordinate species. The time-dependent inactivation of the enzyme with diethyl pyrocarbonate and its kinetic analysis strongly suggested the occurrence of histidine residue. From the above-mentioned spectroscopic results and chemical modification, it was deduced that the native enzyme is predominantly in the high spin, ferric form and has a histidine as the fifth ligand.
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Affiliation(s)
- H D Youn
- Department of Microbiology, College of Natural Sciences, Seoul National University, Republic of Korea
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23
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Youn HD, Kim KJ, Maeng JS, Han YH, Jeong IB, Jeong G, Kang SO, Hah YC. Single electron transfer by an extracellular laccase from the white-rot fungus Pleurotus ostreatus. Microbiology (Reading) 1995; 141 ( Pt 2):393-8. [PMID: 7704270 DOI: 10.1099/13500872-141-2-393] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Two different bands with laccase activity were obtained after nondenaturing PAGE of the culture filtrate of Pleurotus ostreatus. Immunoblot analysis revealed that antisera raised against laccase I were not reactive to laccase II. Laccase I, which exhibited faster mobility on nondenaturing polyacrylamide gel, was purified 42.9-fold with an overall yield of 10.8%. Gel filtration and SDS-PAGE revealed that laccase I is a single polypeptide with a molecular mass of approximately 64 kDa. Laccase I contained 12.5% carbohydrate by weight and 3.9 mol copper (mol protein)-1. The absorption spectrum of laccase I showed a type 1 signal at 605 nm and EPR spectra showed that the parameters of the type 1 and type 2 Cu signals were g parallel = 2.197 and A parallel = 0.009 cm-1, and g parallel = 2.263 and A parallel = 0.0176 cm-1, respectively. The data obtained from the pH profiles suggested that two ionization groups, whose pKa values were 5.60-5.70 and 6.70-6.85, may play an important role in the active site of laccase I as the ligand of copper metal. The optimal pH and temperature for the activity of laccase I were 6.0-6.5 and 30-35 degrees C, respectively. The enzyme had affinity for various lignin-related phenolic compounds: the Km values for ferulic acid and syringic acid were 48 and 89 microM, respectively. EPR spectroscopic study of the action of laccase I on 3,5-dimethoxy-5-hydroxyacetophenone indicated that this enzyme catalyses single electron transfer with the formation of the phenoxy radical as an intermediate.
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Affiliation(s)
- H D Youn
- Department of Microbiology, College of Natural Sciences, Seoul National University, Republic of Korea
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24
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Shin KS, Youn HD, Han YH, Kang SO, Hah YC. Purification and characterisation of D-glucose oxidase from white-rot fungus Pleurotus ostreatus. Eur J Biochem 1993; 215:747-52. [PMID: 8354282 DOI: 10.1111/j.1432-1033.1993.tb18088.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
D-Glucose oxidase was purified 27.5-fold to apparent homogeneity with an overall yield of 23.8%, from Pleurotus ostreatus, through a purification procedure of ammonium sulphate precipitation, gel-permeation, anion-exchange and hydrophobic-interaction chromatography. The molecular mass determined by gel filtration was found to be 290 kDa. SDS/PAGE revealed that the enzyme consists of four subunits with a molecular mass of 70 kDa. The absorption spectra of the enzyme exhibit maxima at 280, 360 and 460 nm. The enzyme shows a fluorescence spectrum with an excitation maximum at 470 nm and an emission maximum at 530 nm. These results indicate that the prosthetic group of the enzyme is flavin and that the enzyme contains 4 mol flavin/mol enzyme. The enzyme is optimally active at 50 degrees C and at pH 5.5-6.0. It exhibits broad affinity for various sugars and specificity for D-glucose with Km value of 1.34 mM. 2,6-Dichloroindophenol, Wurster's blue, and 4-benzoquinone can function as electron acceptors but phenazine methosulphate cannot function as an electron acceptor. The enzyme is inhibited completely by mercuric chloride and partially by silver sulphate, sodium azide 8-hydroxyquinoline.
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Affiliation(s)
- K S Shin
- Department of Microbiology, College of Sciences, Taejon University, South Korea
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25
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Kang SO, Shin KS, Han YH, Youn HD, Hah YC. Purification and characterisation of an extracellular peroxidase from white-rot fungus Pleurotus ostreatus. Biochim Biophys Acta 1993; 1163:158-64. [PMID: 8387825 DOI: 10.1016/0167-4838(93)90177-s] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A peroxidase was purified 98.3-fold from the culture filtrate of Pleurotus ostreatus with an overall yield of 12.4%. The molecular mass determined by gel filtration was found to be approx. 140 kDa. SDS-PAGE revealed that the enzyme consists of two identical subunits with a molecular mass of approx. 72 kDa. The pI value of this enzyme is approx. 4.3. The enzyme contains 41% carbohydrate by weight, and aspartic acid and asparagine (16.8%), and glutamic acid and glutamine (12.0%). The enzyme has the highest affinity toward synaptic acid and affinity towards various phenolic compounds containing methoxyl and p-hydroxyl groups, directly attached to the benzene ring. However, the enzyme does not react with veratryl alcohol and shows no affinity for nonphenolic compounds. The optimal reaction pH and temperature are 4.0 and 40 degrees C, respectively. The catalytic mechanism of the enzymic reaction is of the Ping-Pong type. The activity of the enzyme is competitively inhibited by high concentrations of H2O2 and its Ki value is 1.70 mM against H2O2. This enzyme contains approx. 1 mol of heme per mol of one subunit of the enzyme. The pyridine hemochrome spectrum of the enzyme indicates that the heme of P. ostreatus peroxidase is iron protoporphyrin IX. The EPR spectrum of the native peroxidase shows the presence of a high-spin ferric complex with g values at 6.102, 5.643 and 1.991.
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Affiliation(s)
- S O Kang
- Department of Microbiology, College of Natural Sciences, Seoul National University, South Korea
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26
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Yoon SS, Youn HD, Suh C, Bang YJ, Choi SJ, Kim BK, Kim NK, Kim EC. A case of leukemia-associated arthritis--identification of leukemic cells in synovial fluid by light microscopy. J Korean Med Sci 1987; 2:255-8. [PMID: 3268183 PMCID: PMC3053642 DOI: 10.3346/jkms.1987.2.4.255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
One case of arthritis complicating leukemia is described in which leukemic cells were identified in synovial fluid by light microscopy. Although arthritis is a well-known manifestation of leukemia with an incidence of 13.5%, the pathogenesis often is unclear, and the direct demonstration of leukemic cells in synovial fluid has been very uncommon. A 16 year-old male patient was admitted due to left elbow joint pain and swelling. Synovial fluid examination revealed blast cells and this finding has directed to a final diagnosis of acute lymphoblastic leukemia.
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Affiliation(s)
- S S Yoon
- Department of Internal Medicine, College of Medicine, Seoul National University, Korea
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