1
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Lorton BM, Warren C, Ilyas H, Nandigrami P, Hegde S, Cahill S, Lehman SM, Shabanowitz J, Hunt DF, Fiser A, Cowburn D, Shechter D. Glutamylation of Npm2 and Nap1 acidic disordered regions increases DNA mimicry and histone chaperone efficiency. iScience 2024; 27:109458. [PMID: 38571760 PMCID: PMC10987829 DOI: 10.1016/j.isci.2024.109458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 01/08/2024] [Accepted: 03/07/2024] [Indexed: 04/05/2024] Open
Abstract
Histone chaperones-structurally diverse, non-catalytic proteins enriched with acidic intrinsically disordered regions (IDRs)-protect histones from spurious nucleic acid interactions and guide their deposition into and out of nucleosomes. Despite their conservation and ubiquity, the function of the chaperone acidic IDRs remains unclear. Here, we show that the Xenopus laevis Npm2 and Nap1 acidic IDRs are substrates for TTLL4 (Tubulin Tyrosine Ligase Like 4)-catalyzed post-translational glutamate-glutamylation. We demonstrate that to bind, stabilize, and deposit histones into nucleosomes, chaperone acidic IDRs function as DNA mimetics. Our biochemical, computational, and biophysical studies reveal that glutamylation of these chaperone polyelectrolyte acidic stretches functions to enhance DNA electrostatic mimicry, promoting the binding and stabilization of H2A/H2B heterodimers and facilitating nucleosome assembly. This discovery provides insights into both the previously unclear function of the acidic IDRs and the regulatory role of post-translational modifications in chromatin dynamics.
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Affiliation(s)
- Benjamin M. Lorton
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Christopher Warren
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Humaira Ilyas
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Prithviraj Nandigrami
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Department of Systems & Computational Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Subray Hegde
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Sean Cahill
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Stephanie M. Lehman
- Department of Chemistry, University of Virginia, Charlottesville, VA 22908, USA
| | - Jeffrey Shabanowitz
- Department of Chemistry, University of Virginia, Charlottesville, VA 22908, USA
| | - Donald F. Hunt
- Departments of Chemistry and Pathology, University of Virginia, Charlottesville, VA 22908, USA
| | - Andras Fiser
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Department of Systems & Computational Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - David Cowburn
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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2
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Venkatasubramanian M, Schwartz L, Ramachandra N, Bennett J, Subramanian KR, Chen X, Gordon-Mitchell S, Fromowitz A, Pradhan K, Shechter D, Sahu S, Heiser D, Scherle P, Chetal K, Kulkarni A, Myers KC, Weirauch MT, Grimes HL, Starczynowski DT, Verma A, Salomonis N. Broad de-regulated U2AF1 splicing is prognostic and augments leukemic transformation via protein arginine methyltransferase activation. bioRxiv 2024:2024.02.04.578798. [PMID: 38370617 PMCID: PMC10871255 DOI: 10.1101/2024.02.04.578798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
The role of splicing dysregulation in cancer is underscored by splicing factor mutations; however, its impact in the absence of such rare mutations is poorly understood. To reveal complex patient subtypes and putative regulators of pathogenic splicing in Acute Myeloid Leukemia (AML), we developed a new approach called OncoSplice. Among diverse new subtypes, OncoSplice identified a biphasic poor prognosis signature that partially phenocopies U2AF1-mutant splicing, impacting thousands of genes in over 40% of adult and pediatric AML cases. U2AF1-like splicing co-opted a healthy circadian splicing program, was stable over time and induced a leukemia stem cell (LSC) program. Pharmacological inhibition of the implicated U2AF1-like splicing regulator, PRMT5, rescued leukemia mis-splicing and inhibited leukemic cell growth. Genetic deletion of IRAK4, a common target of U2AF1-like and PRMT5 treated cells, blocked leukemia development in xenograft models and induced differentiation. These analyses reveal a new prognostic alternative-splicing mechanism in malignancy, independent of splicing-factor mutations.
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Affiliation(s)
- Meenakshi Venkatasubramanian
- Division of Biomedical Informatics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
- Department of Electrical Engineering and Computer Science, University of Cincinnati, Cincinnati, OH
| | - Leya Schwartz
- Blood Cancer Institute, Albert Einstein College of Medicine, Montefiore Medical Center, The Bronx, NY
| | - Nandini Ramachandra
- Blood Cancer Institute, Albert Einstein College of Medicine, Montefiore Medical Center, The Bronx, NY
| | - Joshua Bennett
- Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
| | - Krithika R. Subramanian
- Division of Biomedical Informatics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
| | - Xiaoting Chen
- Divisions of Human Genetics and Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
| | - Shanisha Gordon-Mitchell
- Blood Cancer Institute, Albert Einstein College of Medicine, Montefiore Medical Center, The Bronx, NY
| | - Ariel Fromowitz
- Blood Cancer Institute, Albert Einstein College of Medicine, Montefiore Medical Center, The Bronx, NY
| | - Kith Pradhan
- Blood Cancer Institute, Albert Einstein College of Medicine, Montefiore Medical Center, The Bronx, NY
| | - David Shechter
- Blood Cancer Institute, Albert Einstein College of Medicine, Montefiore Medical Center, The Bronx, NY
| | - Srabani Sahu
- Blood Cancer Institute, Albert Einstein College of Medicine, Montefiore Medical Center, The Bronx, NY
| | - Diane Heiser
- Prelude Therapeutics Incorporated, Wilmington, DE
| | | | - Kashish Chetal
- Division of Biomedical Informatics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
| | - Aishwarya Kulkarni
- Division of Biomedical Informatics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
- Department of Electrical Engineering and Computer Science, University of Cincinnati, Cincinnati, OH
| | - Kasiani C. Myers
- Division of Bone Marrow Transplantation and Immune Deficiency, Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH
| | - Matthew T. Weirauch
- Division of Biomedical Informatics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
- Divisions of Human Genetics and Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
| | - H. Leighton Grimes
- Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
- Division of Immunobiology and Center for Systems Immunology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
| | - Daniel T. Starczynowski
- Experimental Hematology and Cancer Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
- Division of Bone Marrow Transplantation and Immune Deficiency, Cancer and Blood Diseases Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
| | - Amit Verma
- Blood Cancer Institute, Albert Einstein College of Medicine, Montefiore Medical Center, The Bronx, NY
| | - Nathan Salomonis
- Division of Biomedical Informatics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
- Department of Electrical Engineering and Computer Science, University of Cincinnati, Cincinnati, OH
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH
- Division of Immunobiology and Center for Systems Immunology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
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3
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Lorton BM, Warren C, Ilyas H, Nandigrami P, Hegde S, Cahill S, Lehman SM, Shabanowitz J, Hunt DF, Fiser A, Cowburn D, Shechter D. Glutamylation of Npm2 and Nap1 acidic disordered regions increases DNA charge mimicry to enhance chaperone efficiency. bioRxiv 2023:2023.09.18.558337. [PMID: 37790377 PMCID: PMC10542154 DOI: 10.1101/2023.09.18.558337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Histone chaperones-structurally diverse, non-catalytic proteins enriched with acidic intrinsically disordered regions (IDRs)-protect histones from spurious nucleic acid interactions and guide their deposition into and out of nucleosomes. Despite their conservation and ubiquity, the function of the chaperone acidic IDRs remains unclear. Here, we show that the Xenopus laevis Npm2 and Nap1 acidic IDRs are substrates for TTLL4 (Tubulin Tyrosine Ligase Like 4)-catalyzed post-translational glutamate-glutamylation. We demonstrate that, to bind, stabilize, and deposit histones into nucleosomes, chaperone acidic IDRs function as DNA mimetics. Our biochemical, computational, and biophysical studies reveal that glutamylation of these chaperone polyelectrolyte acidic stretches functions to enhance DNA electrostatic mimicry, promoting the binding and stabilization of H2A/H2B heterodimers and facilitating nucleosome assembly. This discovery provides insights into both the previously unclear function of the acidic IDRs and the regulatory role of post-translational modifications in chromatin dynamics.
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Affiliation(s)
- Benjamin M. Lorton
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Christopher Warren
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461
- Current address: Merck & Co., Inc., 2025 E Scott Ave., Rahway, NJ 07065
| | - Humaira Ilyas
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Prithviraj Nandigrami
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461
- Department of Systems & Computational Biology, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Subray Hegde
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Sean Cahill
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Stephanie M Lehman
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904
- GSK, Collegeville, Pennsylvania 19426
| | | | - Donald F. Hunt
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904
- Departments of Chemistry and Pathology, University of Virginia, Charlottesville, VA 22904
| | - Andras Fiser
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461
- Department of Systems & Computational Biology, Albert Einstein College of Medicine, Bronx, NY 10461
| | - David Cowburn
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461
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Chi P, Lewis PW, Lu C, Lu J, Ruthenburg AJ, Sabari BR, Shechter D, Wan L, Wang GG. Charles David Allis (1951-2023). Nat Genet 2023; 55:522-523. [PMID: 36849658 DOI: 10.1038/s41588-023-01331-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Affiliation(s)
- Ping Chi
- Human Oncology and Pathogenesis Program, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Peter W Lewis
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Chao Lu
- Department of Genetics and Development, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA.
| | - Janice Lu
- Division of Medical Oncology, Department of Medicine, University of Southern California Norris Comprehensive Cancer Center, Los Angeles, CA, USA
| | - Alexander J Ruthenburg
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL, USA
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Benjamin R Sabari
- Laboratory of Nuclear Organization, Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Liling Wan
- Department of Cancer Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Gang Greg Wang
- Lineberger Comprehensive Cancer Center, Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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Maron MI, Casill AD, Gupta V, Roth JS, Sidoli S, Query CC, Gamble MJ, Shechter D. Type I and II PRMTs inversely regulate post-transcriptional intron detention through Sm and CHTOP methylation. eLife 2022; 11:e72867. [PMID: 34984976 PMCID: PMC8765754 DOI: 10.7554/elife.72867] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [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] [Received: 08/06/2021] [Accepted: 01/03/2022] [Indexed: 12/26/2022] Open
Abstract
Protein arginine methyltransferases (PRMTs) are required for the regulation of RNA processing factors. Type I PRMT enzymes catalyze mono- and asymmetric dimethylation; Type II enzymes catalyze mono- and symmetric dimethylation. To understand the specific mechanisms of PRMT activity in splicing regulation, we inhibited Type I and II PRMTs and probed their transcriptomic consequences. Using the newly developed Splicing Kinetics and Transcript Elongation Rates by Sequencing (SKaTER-seq) method, analysis of co-transcriptional splicing demonstrated that PRMT inhibition resulted in altered splicing rates. Surprisingly, co-transcriptional splicing kinetics did not correlate with final changes in splicing of polyadenylated RNA. This was particularly true for retained introns (RI). By using actinomycin D to inhibit ongoing transcription, we determined that PRMTs post-transcriptionally regulate RI. Subsequent proteomic analysis of both PRMT-inhibited chromatin and chromatin-associated polyadenylated RNA identified altered binding of many proteins, including the Type I substrate, CHTOP, and the Type II substrate, SmB. Targeted mutagenesis of all methylarginine sites in SmD3, SmB, and SmD1 recapitulated splicing changes seen with Type II PRMT inhibition, without disrupting snRNP assembly. Similarly, mutagenesis of all methylarginine sites in CHTOP recapitulated the splicing changes seen with Type I PRMT inhibition. Examination of subcellular fractions further revealed that RI were enriched in the nucleoplasm and chromatin. Taken together, these data demonstrate that, through Sm and CHTOP arginine methylation, PRMTs regulate the post-transcriptional processing of nuclear, detained introns.
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Affiliation(s)
- Maxim I Maron
- Department of Biochemistry, Albert Einstein College of MedicineBronxUnited States
| | - Alyssa D Casill
- Department of Molecular Pharmacology, Albert Einstein College of MedicineBronxUnited States
| | - Varun Gupta
- Department of Cell Biology, Albert Einstein College of MedicineBronxUnited States
| | - Jacob S Roth
- Department of Biochemistry, Albert Einstein College of MedicineBronxUnited States
| | - Simone Sidoli
- Department of Biochemistry, Albert Einstein College of MedicineBronxUnited States
| | - Charles C Query
- Department of Cell Biology, Albert Einstein College of MedicineBronxUnited States
| | - Matthew J Gamble
- Department of Molecular Pharmacology, Albert Einstein College of MedicineBronxUnited States
- Department of Cell Biology, Albert Einstein College of MedicineBronxUnited States
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of MedicineBronxUnited States
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Maron MI, Lehman SM, Gayatri S, DeAngelo JD, Hegde S, Lorton BM, Sun Y, Bai DL, Sidoli S, Gupta V, Marunde MR, Bone JR, Sun ZW, Bedford MT, Shabanowitz J, Chen H, Hunt DF, Shechter D. Independent transcriptomic and proteomic regulation by type I and II protein arginine methyltransferases. iScience 2021; 24:102971. [PMID: 34505004 PMCID: PMC8417332 DOI: 10.1016/j.isci.2021.102971] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 06/21/2021] [Accepted: 08/09/2021] [Indexed: 12/22/2022] Open
Abstract
Protein arginine methyltransferases (PRMTs) catalyze the post-translational monomethylation (Rme1), asymmetric (Rme2a), or symmetric (Rme2s) dimethylation of arginine. To determine the cellular consequences of type I (Rme2a) and II (Rme2s) PRMTs, we developed and integrated multiple approaches. First, we determined total cellular dimethylarginine levels, revealing that Rme2s was ∼3% of total Rme2 and that this percentage was dependent upon cell type and PRMT inhibition status. Second, we quantitatively characterized in vitro substrates of the major enzymes and expanded upon PRMT substrate recognition motifs. We also compiled our data with publicly available methylarginine-modified residues into a comprehensive database. Third, we inhibited type I and II PRMTs and performed proteomic and transcriptomic analyses to reveal their phenotypic consequences. These experiments revealed both overlapping and independent PRMT substrates and cellular functions. Overall, this study expands upon PRMT substrate diversity, the arginine methylome, and the complex interplay of type I and II PRMTs.
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Affiliation(s)
- Maxim I. Maron
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Stephanie M. Lehman
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
| | - Sitaram Gayatri
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, TX, USA
- Center for Cancer Epigenetics, The University of Texas MD Anderson Cancer Center, Smithville, TX, USA
- Graduate Program in Genetics and Epigenetics, The University of Texas MD Anderson UT Health Graduate School of Biomedical Sciences, Houston, TX 77030, USA
| | - Joseph D. DeAngelo
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Subray Hegde
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Benjamin M. Lorton
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Yan Sun
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Dina L. Bai
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
| | - Simone Sidoli
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Varun Gupta
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | | | - James R. Bone
- EpiCypher, Inc., Research Triangle Park, NC 27709, USA
| | - Zu-Wen Sun
- EpiCypher, Inc., Research Triangle Park, NC 27709, USA
| | - Mark T. Bedford
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, TX, USA
- Center for Cancer Epigenetics, The University of Texas MD Anderson Cancer Center, Smithville, TX, USA
- Graduate Program in Genetics and Epigenetics, The University of Texas MD Anderson UT Health Graduate School of Biomedical Sciences, Houston, TX 77030, USA
| | - Jeffrey Shabanowitz
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
| | - Hongshan Chen
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Donald F. Hunt
- Departments of Chemistry and Pathology, University of Virginia, Charlottesville, VA 22904, USA
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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7
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Ravichandran M, Lei R, Tang Q, Zhao Y, Lee J, Ma L, Chrysanthou S, Lorton BM, Cvekl A, Shechter D, Zheng D, Dawlaty MM. Rinf Regulates Pluripotency Network Genes and Tet Enzymes in Embryonic Stem Cells. Cell Rep 2020; 28:1993-2003.e5. [PMID: 31433977 PMCID: PMC6716522 DOI: 10.1016/j.celrep.2019.07.080] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 06/07/2019] [Accepted: 07/23/2019] [Indexed: 11/30/2022] Open
Abstract
The Retinoid inducible nuclear factor (Rinf), also known as CXXC5, is a nuclear protein, but its functions in the context of the chromatin are poorly defined. We find that in mouse embryonic stem cells (mESCs), Rinf binds to the chromatin and is enriched at promoters and enhancers of Tet1, Tet2, and pluripotency genes. The Rinf-bound regions show significant overlapping occupancy of pluripotency factors Nanog, Oct4, and Sox2, as well as Tet1 and Tet2. We found that Rinf forms a complex with Nanog, Oct4, Tet1, and Tet2 and facilitates their proper recruitment to regulatory regions of pluripotency and Tet genes in ESCs to positively regulate their transcription. Rinf deficiency in ESCs reduces expression of Rinf target genes, including several pluripotency factors and Tet enzymes, and causes aberrant differentiation. Together, our findings establish Rinf as a regulator of the pluripotency network genes and Tet enzymes in ESCs.
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Affiliation(s)
- Mirunalini Ravichandran
- Ruth L. and David S. Gottesman Institute for Stem Cell and Regenerative Medicine Research, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA; Department of Genetics, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA
| | - Run Lei
- Ruth L. and David S. Gottesman Institute for Stem Cell and Regenerative Medicine Research, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA; Department of Genetics, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA
| | - Qin Tang
- Ruth L. and David S. Gottesman Institute for Stem Cell and Regenerative Medicine Research, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA; Department of Genetics, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA
| | - Yilin Zhao
- Department of Genetics, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA
| | - Joun Lee
- Ruth L. and David S. Gottesman Institute for Stem Cell and Regenerative Medicine Research, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA; Department of Genetics, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA
| | - Liyang Ma
- Ruth L. and David S. Gottesman Institute for Stem Cell and Regenerative Medicine Research, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA; Department of Genetics, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA
| | - Stephanie Chrysanthou
- Ruth L. and David S. Gottesman Institute for Stem Cell and Regenerative Medicine Research, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA; Department of Genetics, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA
| | - Benjamin M Lorton
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA
| | - Ales Cvekl
- Department of Genetics, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA
| | - Deyou Zheng
- Department of Genetics, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA; Departments of Neurology and Neuroscience, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA
| | - Meelad M Dawlaty
- Ruth L. and David S. Gottesman Institute for Stem Cell and Regenerative Medicine Research, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA; Department of Genetics, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY 10461, USA.
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8
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Warren C, Bonanno JB, Almo SC, Shechter D. Structure of a single-chain H2A/H2B dimer. Acta Crystallogr F Struct Biol Commun 2020; 76:194-198. [DOI: 10.1107/s2053230x20004604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 04/02/2020] [Indexed: 08/30/2023] Open
Abstract
Chromatin is the complex assembly of nucleic acids and proteins that makes up the physiological form of the eukaryotic genome. The nucleosome is the fundamental repeating unit of chromatin, and is composed of ∼147 bp of DNA wrapped around a histone octamer formed by two copies of each core histone: H2A, H2B, H3 and H4. Prior to nucleosome assembly, and during histone eviction, histones are typically assembled into soluble H2A/H2B dimers and H3/H4 dimers and tetramers. A multitude of factors interact with soluble histone dimers and tetramers, including chaperones, importins, histone-modifying enzymes and chromatin-remodeling enzymes. It is still unclear how many of these proteins recognize soluble histones; therefore, there is a need for new structural tools to study non-nucleosomal histones. Here, a single-chain, tailless Xenopus H2A/H2B dimer was created by directly fusing the C-terminus of H2B to the N-terminus of H2A. It is shown that this construct (termed scH2BH2A) is readily expressed in bacteria and can be purified under non-denaturing conditions. A 1.31 Å resolution crystal structure of scH2BH2A shows that it adopts a conformation that is nearly identical to that of nucleosomal H2A/H2B. This new tool is likely to facilitate future structural studies of many H2A/H2B-interacting proteins.
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9
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Lorton BM, Harijan RK, Burgos ES, Bonanno JB, Almo SC, Shechter D. A Binary Arginine Methylation Switch on Histone H3 Arginine 2 Regulates Its Interaction with WDR5. Biochemistry 2020; 59:3696-3708. [PMID: 32207970 DOI: 10.1021/acs.biochem.0c00035] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Histone H3 arginine 2 (H3R2) is post-translationally modified in three different states by "writers" of the protein arginine methyltransferase (PRMT) family. H3R2 methylarginine isoforms include PRMT5-catalyzed monomethylation (me1) and symmetric dimethylation (me2s) and PRMT6-catalyzed me1 and asymmetric dimethylation (me2a). WD-40 repeat-containing protein 5 (WDR5) is an epigenetic "reader" protein that interacts with H3R2. Previous studies suggested that H3R2me2s specified a high-affinity interaction with WDR5. However, our prior biological data prompted the hypothesis that WDR5 may also interact with H3R2me1. Here, using highly accurate quantitative binding analysis combined with high-resolution crystal structures of WDR5 in complex with unmodified (me0) and me1/me2s l-arginine amino acids and in complex with the H3R2me1 peptide, we provide a rigorous biochemical study and address long-standing discrepancies of this important biological interaction. Despite modest structural differences at the binding interface, our study supports an interaction model regulated by a binary arginine methylation switch: H3R2me2a prevents interaction with WDR5, whereas H3R2me0, -me1, and -me2s are equally permissive.
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Affiliation(s)
- Benjamin M Lorton
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - Rajesh K Harijan
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - Emmanuel S Burgos
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - Jeffrey B Bonanno
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - Steven C Almo
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
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10
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Walters RO, Arias E, Diaz A, Burgos ES, Guan F, Tiano S, Mao K, Green CL, Qiu Y, Shah H, Wang D, Hudgins AD, Tabrizian T, Tosti V, Shechter D, Fontana L, Kurland IJ, Barzilai N, Cuervo AM, Promislow DEL, Huffman DM. Sarcosine Is Uniquely Modulated by Aging and Dietary Restriction in Rodents and Humans. Cell Rep 2019; 25:663-676.e6. [PMID: 30332646 DOI: 10.1016/j.celrep.2018.09.065] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 08/02/2018] [Accepted: 09/19/2018] [Indexed: 02/06/2023] Open
Abstract
A hallmark of aging is a decline in metabolic homeostasis, which is attenuated by dietary restriction (DR). However, the interaction of aging and DR with the metabolome is not well understood. We report that DR is a stronger modulator of the rat metabolome than age in plasma and tissues. A comparative metabolomic screen in rodents and humans identified circulating sarcosine as being similarly reduced with aging and increased by DR, while sarcosine is also elevated in long-lived Ames dwarf mice. Pathway analysis in aged sarcosine-replete rats identify this biogenic amine as an integral node in the metabolome network. Finally, we show that sarcosine can activate autophagy in cultured cells and enhances autophagic flux in vivo, suggesting a potential role in autophagy induction by DR. Thus, these data identify circulating sarcosine as a biomarker of aging and DR in mammalians and may contribute to age-related alterations in the metabolome and in proteostasis.
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Affiliation(s)
- Ryan O Walters
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA; Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA; Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Esperanza Arias
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA; Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Antonio Diaz
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA; Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Emmanuel S Burgos
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Fangxia Guan
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA; Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Simoni Tiano
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA; Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Kai Mao
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA; Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA; Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Cara L Green
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, Scotland, UK
| | - Yungping Qiu
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA; Einstein-Mount Sinai Diabetes Research Center, Stable Isotope and Metabolomics Core Facility, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Hardik Shah
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA; Einstein-Mount Sinai Diabetes Research Center, Stable Isotope and Metabolomics Core Facility, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Donghai Wang
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA; Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Adam D Hudgins
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Tahmineh Tabrizian
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA; Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Valeria Tosti
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Luigi Fontana
- Charles Perkins Centre, The University of Sydney, NSW 2006, Australia; Central Clinical School, The University of Sydney, NSW 2006, Australia; Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Clinical and Experimental Sciences, Brescia University Medical School, Brescia, Italy
| | - Irwin J Kurland
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA; Einstein-Mount Sinai Diabetes Research Center, Stable Isotope and Metabolomics Core Facility, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Nir Barzilai
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA; Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, USA; Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Ana Maria Cuervo
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA; Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Daniel E L Promislow
- Department of Pathology, University of Washington, Seattle, WA, USA; Department of Biology, University of Washington, Seattle, WA, USA
| | - Derek M Huffman
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA; Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA; Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, USA.
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11
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Abstract
Arginine methylation is a ubiquitous post-translational modification. Three predominant types of arginine-guanidino methylation occur in Eukarya: mono (Rme1/MMA), symmetric (Rme2s/SDMA), and asymmetric (Rme2a/ADMA). Arginine methylation frequently occurs at sites of protein-protein and protein-nucleic acid interactions, providing specificity for binding partners and stabilization of important biological interactions in diverse cellular processes. Each methylarginine isoform-catalyzed by members of the protein arginine methyltransferase family, Type I (PRMT1-4,6,8) and Type II (PRMT5,9)-has unique downstream consequences. Methylarginines are found in ordered domains, domains of low complexity, and in intrinsically disordered regions of proteins-the latter two of which are intimately connected with biological liquid-liquid phase separation. This review highlights discoveries illuminating how arginine methylation affects genome integrity, gene transcription, mRNA splicing and mRNP biology, protein translation and stability, and phase separation. As more proteins and processes are found to be regulated by arginine methylation, its importance for understanding cellular physiology will continue to grow.
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Affiliation(s)
- Benjamin M Lorton
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
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12
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Abstract
Xenopus laevis development is marked by accelerated cell division solely supported by the proteins maternally deposited in the egg. Oocytes mature to eggs with concomitant transcriptional silencing. The unique maternal chromatin state contributing to this silencing and subsequent zygotic activation is likely established by histone posttranslational modifications and histone variants. Therefore, tools for understanding the nature and function of maternal and embryonic histones are essential to deciphering mechanisms of regulation of development, chromatin assembly, and transcription. Here we describe protocols for isolating pronuclear sperm chromatin from Xenopus egg extracts and hydroxyapatite-based histone purification from this chromatin. The histones purified through this method can be directly assembled into chromatin through in vitro assembly reactions, providing a unique opportunity to biochemically dissect the effect of histone variants, histone modifications, and other factors in chromatin replication and assembly. We also describe how to isolate chromatin from staged embryos and analyze the proteins to reveal dynamic developmental histone modifications. Finally, we present protocols to measure chromatin assembly in extracts, including supercoiling and micrococcal nuclease assays. Using these approaches, analysis of maternal and zygotic histone posttranslational modifications concomitant with cell-cycle and developmental transitions can be tested.
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Affiliation(s)
- Wei-Lin Wang
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Takashi Onikubo
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461
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13
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Abstract
Chromatin, primarily a complex of DNA and histone proteins, is the physiological form of the genome. Chromatin is generally repressive for transcription and other information transactions that occur on DNA. A wealth of post-translational modifications on canonical histones and histone variants encode regulatory information to recruit or repel effector proteins on chromatin, promoting and further repressing transcription and thereby form the basis of epigenetic information. During metazoan oogenesis, large quantities of histone proteins are synthesized and stored in preparation for the rapid early cell cycles of development and to elicit maternal control of chromatin assembly pathways. Oocyte and egg cell-free extracts of the frog Xenopus laevis are a compelling model system for the study of chromatin assembly and transcription, precisely because they exist in an extreme state primed for rapid chromatin assembly or for transcriptional activity. We show that chromatin assembly rates are slower in the X. laevis oocyte than in egg extracts, while conversely, only oocyte extracts transcribe template plasmids. We demonstrate that rapid chromatin assembly in egg extracts represses RNA Polymerase II dependent transcription, while pre-binding of TATA-Binding Protein (TBP) to a template plasmid promotes transcription. Our experimental evidence presented here supports a model in which chromatin assembly and transcription are in competition and that the onset of zygotic genomic activation may be in part due to stable transcriptional complex assembly.
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Affiliation(s)
- Wei-Lin Wang
- Department of Biochemistry. Albert Einstein College of Medicine, Bronx, NY, USA
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14
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Abstract
Chromatin is the complex of DNA and histone proteins that is the physiological form of the eukaryotic genome. Chromatin is generally repressive for transcription, especially so during early metazoan development when maternal factors are explicitly in control of new zygotic gene expression. In the important model organism Xenopus laevis, maturing oocytes are transcriptionally active with reduced rates of chromatin assembly, while laid eggs and fertilized embryos have robust rates of chromatin assembly and are transcriptionally repressed. As the DNA-to-cytoplasmic ratio decreases approaching the mid-blastula transition (MBT) and the onset of zygotic genome activation (ZGA), the chromatin assembly process changes with the concomitant reduction in maternal chromatin components. Chromatin assembly is mediated in part by histone chaperones that store maternal histones and release them into new zygotic chromatin. Here, we review literature on chromatin and transcription in frog embryos and cell-free extracts and highlight key insights demonstrating the roles of maternal and zygotic histone deposition and their relationship with transcriptional regulation. We explore the central historical and recent literature on the use of Xenopus embryos and the key contributions provided by experiments in cell-free oocyte and egg extracts for the interplay between histone chaperones, chromatin assembly, and transcriptional regulation. Ongoing and future studies in Xenopus cell free extracts will likely contribute essential new insights into the interplay between chromatin assembly and transcriptional regulation.
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Affiliation(s)
- Takashi Onikubo
- Department of Biochemistry. Albert Einstein College of Medicine, Bronx, NY, USA
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15
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Warren C, Matsui T, Karp JM, Onikubo T, Cahill S, Brenowitz M, Cowburn D, Girvin M, Shechter D. Dynamic intramolecular regulation of the histone chaperone nucleoplasmin controls histone binding and release. Nat Commun 2017; 8:2215. [PMID: 29263320 PMCID: PMC5738438 DOI: 10.1038/s41467-017-02308-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 11/17/2017] [Indexed: 12/21/2022] Open
Abstract
Nucleoplasmin (Npm) is a highly conserved histone chaperone responsible for the maternal storage and zygotic release of histones H2A/H2B. Npm contains a pentameric N-terminal core domain and an intrinsically disordered C-terminal tail domain. Though intrinsically disordered regions are common among histone chaperones, their roles in histone binding and chaperoning remain unclear. Using an NMR-based approach, here we demonstrate that the Xenopus laevis Npm tail domain controls the binding of histones at its largest acidic stretch (A2) via direct competition with both the C-terminal basic stretch and basic nuclear localization signal. NMR and small-angle X-ray scattering (SAXS) structural analyses allowed us to construct models of both the tail domain and the pentameric complex. Functional analyses demonstrate that these competitive intramolecular interactions negatively regulate Npm histone chaperone activity in vitro. Together these data establish a potentially generalizable mechanism of histone chaperone regulation via dynamic and specific intramolecular shielding of histone interaction sites.
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Affiliation(s)
- Christopher Warren
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - Tsutomu Matsui
- Department of Chemistry, Stanford University, Stanford Synchrotron Radiation Lightsource, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - Jerome M Karp
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - Takashi Onikubo
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
- Laboratory of Biochemistry and Molecular Biology, Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA
| | - Sean Cahill
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - Michael Brenowitz
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - David Cowburn
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - Mark Girvin
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY, 10461, USA.
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16
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Burgos ES, Walters RO, Huffman DM, Shechter D. A simplified characterization of S-adenosyl-l-methionine-consuming enzymes with 1-Step EZ-MTase: a universal and straightforward coupled-assay for in vitro and in vivo setting. Chem Sci 2017; 8:6601-6612. [PMID: 29449933 PMCID: PMC5676521 DOI: 10.1039/c7sc02830j] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 07/25/2017] [Indexed: 01/02/2023] Open
Abstract
Methyltransferases use S-adenosyl-l-methionine (SAM) to deposit methyl marks. Many of these epigenetic 'writers' are associated with gene regulation. As cancer etiology is highly correlated with misregulated methylation patterns, methyltransferases are emerging therapeutic targets. Successful assignment of methyltransferases' roles within intricate biological networks relies on (1) the access to enzyme mechanistic insights and (2) the efficient screening of chemical probes against these targets. To characterize methyltransferases in vitro and in vivo, we report a highly-sensitive one-step deaminase-linked continuous assay where the S-adenosyl-l-homocysteine (SAH) enzyme-product is rapidly and quantitatively catabolized to S-inosyl-l-homocysteine (SIH). To highlight the broad capabilities of this assay, we established enzymatic characteristics of two protein arginine methyltransferases (PRMT5 and PRMT7), a histone-lysine N-methyltransferase (DIM-5) and a sarcosine/dimethylglycine N-methyltransferase (SDMT). Since the coupling deaminase TM0936 displays robust activity over a broad pH-range we determined the pH dependence of SDMT reaction rates. TM0936 reactions are monitored at 263 nm, so a drawback may arise when methyl acceptor substrates absorb within this UV-range. To overcome this limitation, we used an isosteric fluorescent SAM-analog: S-8-aza-adenosyl-l-methionine. Most enzymes tolerated this probe and sustained methyltransfers were efficiently monitored through loss of fluorescence at 360 nm. Unlike discontinuous radioactive- and antibody-based assays, our assay provides a simple, versatile and affordable approach towards the characterization of methyltransferases. Supported by three logs of linear dynamic range, the 1-Step EZ-MTase can detect methylation rates as low as 2 μM h-1, thus making it possible to quantify low nanomolar concentrations of glycine N-methyltransferase within crude biological samples. With Z'-factors above 0.75, this assay is well suited to high-throughput screening and may promote the identification of novel therapeutics.
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Affiliation(s)
- Emmanuel S Burgos
- Department of Biochemistry , Albert Einstein College of Medicine , 1300 Morris Park Avenue , Bronx , New York 10461 , USA . ; ; ; Tel: +1-718-430-4120 ; Tel: +1-718-430-4128
| | - Ryan O Walters
- Department of Molecular Pharmacology , Albert Einstein College of Medicine , 1300 Morris Park Avenue , Bronx , New York 10461 , USA.,Department of Medicine , Albert Einstein College of Medicine , 1300 Morris Park Avenue , Bronx , New York 10461 , USA.,Department of Institute for Aging Research , Albert Einstein College of Medicine , 1300 Morris Park Avenue , Bronx , New York 10461 , USA
| | - Derek M Huffman
- Department of Molecular Pharmacology , Albert Einstein College of Medicine , 1300 Morris Park Avenue , Bronx , New York 10461 , USA.,Department of Medicine , Albert Einstein College of Medicine , 1300 Morris Park Avenue , Bronx , New York 10461 , USA.,Department of Institute for Aging Research , Albert Einstein College of Medicine , 1300 Morris Park Avenue , Bronx , New York 10461 , USA
| | - David Shechter
- Department of Biochemistry , Albert Einstein College of Medicine , 1300 Morris Park Avenue , Bronx , New York 10461 , USA . ; ; ; Tel: +1-718-430-4120 ; Tel: +1-718-430-4128
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17
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Warren C, Shechter D. Fly Fishing for Histones: Catch and Release by Histone Chaperone Intrinsically Disordered Regions and Acidic Stretches. J Mol Biol 2017; 429:2401-2426. [PMID: 28610839 DOI: 10.1016/j.jmb.2017.06.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 06/05/2017] [Accepted: 06/06/2017] [Indexed: 01/21/2023]
Abstract
Chromatin is the complex of eukaryotic DNA and proteins required for the efficient compaction of the nearly 2-meter-long human genome into a roughly 10-micron-diameter cell nucleus. The fundamental repeating unit of chromatin is the nucleosome: 147bp of DNA wrapped about an octamer of histone proteins. Nucleosomes are stable enough to organize the genome yet must be dynamically displaced and reassembled to allow access to the underlying DNA for transcription, replication, and DNA damage repair. Histone chaperones are a non-catalytic group of proteins that are central to the processes of nucleosome assembly and disassembly and thus the fluidity of the ever-changing chromatin landscape. Histone chaperones are responsible for binding the highly basic histone proteins, shielding them from non-specific interactions, facilitating their deposition onto DNA, and aiding in their eviction from DNA. Although most histone chaperones perform these common functions, recent structural studies of many different histone chaperones reveal that there are few commonalities in their folds. Importantly, sequence-based predictions show that histone chaperones are highly enriched in intrinsically disordered regions (IDRs) and acidic stretches. In this review, we focus on the molecular mechanisms underpinning histone binding, selectivity, and regulation of these highly dynamic protein regions. We highlight new evidence suggesting that IDRs are often critical for histone chaperone function and play key roles in chromatin assembly and disassembly pathways.
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Affiliation(s)
- Christopher Warren
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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18
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Sun J, Zhao Y, McGreal R, Cohen-Tayar Y, Rockowitz S, Wilczek C, Ashery-Padan R, Shechter D, Zheng D, Cvekl A. Pax6 associates with H3K4-specific histone methyltransferases Mll1, Mll2, and Set1a and regulates H3K4 methylation at promoters and enhancers. Epigenetics Chromatin 2016; 9:37. [PMID: 27617035 PMCID: PMC5018195 DOI: 10.1186/s13072-016-0087-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 08/31/2016] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Pax6 is a key regulator of the entire cascade of ocular lens formation through specific binding to promoters and enhancers of batteries of target genes. The promoters and enhancers communicate with each other through DNA looping mediated by multiple protein-DNA and protein-protein interactions and are marked by specific combinations of histone posttranslational modifications (PTMs). Enhancers are distinguished from bulk chromatin by specific modifications of core histone H3, including H3K4me1 and H3K27ac, while promoters show increased H3K4me3 PTM. Previous studies have shown the presence of Pax6 in as much as 1/8 of lens-specific enhancers but a much smaller fraction of tissue-specific promoters. Although Pax6 is known to interact with EP300/p300 histone acetyltransferase responsible for generation of H3K27ac, a potential link between Pax6 and histone H3K4 methylation remains to be established. RESULTS Here we show that Pax6 co-purifies with H3K4 methyltransferase activity in lens cell nuclear extracts. Proteomic studies show that Pax6 immunoprecipitates with Set1a, Mll1, and Mll2 enzymes, and their associated proteins, i.e., Wdr5, Rbbp5, Ash2l, and Dpy30. ChIP-seq studies using chromatin prepared from mouse lens and cultured lens cells demonstrate that Pax6-bound regions are mostly enriched with H3K4me2 and H3K4me1 in enhancers and promoters, though H3K4me3 marks only Pax6-containing promoters. The shRNA-mediated knockdown of Pax6 revealed down-regulation of a set of direct target genes, including Cap2, Farp1, Pax6, Plekha1, Prox1, Tshz2, and Zfp536. Pax6 knockdown was accompanied by reduced H3K4me1 at enhancers and H3K4me3 at promoters, with little or no changes of the H3K4me2 modifications. These changes were prominent in Plekha1, a gene regulated by Pax6 in both lens and retinal pigmented epithelium. CONCLUSIONS Our study supports a general model of Pax6-mediated recruitment of histone methyltransferases Mll1 and Mll2 to lens chromatin, especially at distal enhancers. Genome-wide data in lens show that Pax6 binding correlates with H3K4me2, consistent with the idea that H3K4me2 PTMs correlate with the binding of transcription factors. Importantly, partial reduction of Pax6 induces prominent changes in local H3K4me1 and H3K4me3 modification. Together, these data open the field to mechanistic studies of Pax6, Mll1, Mll2, and H3K4me1/2/3 dynamics at distal enhancers and promoters of developmentally controlled genes.
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Affiliation(s)
- Jian Sun
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461 USA
| | - Yilin Zhao
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461 USA
| | - Rebecca McGreal
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461 USA ; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY 10461 USA
| | - Yamit Cohen-Tayar
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Sagol school of Neuroscience, Tel-Aviv University, Tel Aviv, 69978 Israel
| | - Shira Rockowitz
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461 USA
| | - Carola Wilczek
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461 USA
| | - Ruth Ashery-Padan
- Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Sagol school of Neuroscience, Tel-Aviv University, Tel Aviv, 69978 Israel
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461 USA
| | - Deyou Zheng
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461 USA ; Department of Neurology, Albert Einstein College of Medicine, Bronx, NY 10461 USA ; Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461 USA
| | - Ales Cvekl
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461 USA ; Department of Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY 10461 USA
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19
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Stopa N, Krebs JE, Shechter D. The PRMT5 arginine methyltransferase: many roles in development, cancer and beyond. Cell Mol Life Sci 2015; 72:2041-59. [PMID: 25662273 PMCID: PMC4430368 DOI: 10.1007/s00018-015-1847-9] [Citation(s) in RCA: 312] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Revised: 01/10/2015] [Accepted: 01/29/2015] [Indexed: 10/24/2022]
Abstract
Post-translational arginine methylation is responsible for regulation of many biological processes. The protein arginine methyltransferase 5 (PRMT5, also known as Hsl7, Jbp1, Skb1, Capsuleen, or Dart5) is the major enzyme responsible for mono- and symmetric dimethylation of arginine. An expanding literature demonstrates its critical biological function in a wide range of cellular processes. Histone and other protein methylation by PRMT5 regulate genome organization, transcription, stem cells, primordial germ cells, differentiation, the cell cycle, and spliceosome assembly. Metazoan PRMT5 is found in complex with the WD-repeat protein MEP50 (also known as Wdr77, androgen receptor coactivator p44, or Valois). PRMT5 also directly associates with a range of other protein factors, including pICln, Menin, CoPR5 and RioK1 that may alter its subcellular localization and protein substrate selection. Protein substrate and PRMT5-MEP50 post-translation modifications induce crosstalk to regulate PRMT5 activity. Crystal structures of C. elegans PRMT5 and human and frog PRMT5-MEP50 complexes provide substantial insight into the mechanisms of substrate recognition and procession to dimethylation. Enzymological studies of PRMT5 have uncovered compelling insights essential for future development of specific PRMT5 inhibitors. In addition, newly accumulating evidence implicates PRMT5 and MEP50 expression levels and their methyltransferase activity in cancer tumorigenesis, and, significantly, as markers of poor clinical outcome, marking them as potential oncogenes. Here, we review the substantial new literature on PRMT5 and its partners to highlight the significance of understanding this essential enzyme in health and disease.
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Affiliation(s)
- Nicole Stopa
- Department of Biological Sciences, University of Alaska Anchorage, 3211 Providence Drive, Anchorage, AK 99508, USA
| | - Jocelyn E. Krebs
- Department of Biological Sciences, University of Alaska Anchorage, 3211 Providence Drive, Anchorage, AK 99508, USA
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine of Yeshiva University, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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20
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Burgos ES, Wilczek C, Onikubo T, Bonanno JB, Jansong J, Reimer U, Shechter D. Histone H2A and H4 N-terminal tails are positioned by the MEP50 WD repeat protein for efficient methylation by the PRMT5 arginine methyltransferase. J Biol Chem 2015; 290:9674-89. [PMID: 25713080 DOI: 10.1074/jbc.m115.636894] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Indexed: 11/06/2022] Open
Abstract
The protein arginine methyltransferase PRMT5 is complexed with the WD repeat protein MEP50 (also known as Wdr77 or androgen coactivator p44) in vertebrates in a tetramer of heterodimers. MEP50 is hypothesized to be required for protein substrate recruitment to the catalytic domain of PRMT5. Here we demonstrate that the cross-dimer MEP50 is paired with its cognate PRMT5 molecule to promote histone methylation. We employed qualitative methylation assays and a novel ultrasensitive continuous assay to measure enzyme kinetics. We demonstrate that neither full-length human PRMT5 nor the Xenopus laevis PRMT5 catalytic domain has appreciable protein methyltransferase activity. We show that histones H4 and H3 bind PRMT5-MEP50 more efficiently compared with histone H2A(1-20) and H4(1-20) peptides. Histone binding is mediated through histone fold interactions as determined by competition experiments and by high density histone peptide array interaction studies. Nucleosomes are not a substrate for PRMT5-MEP50, consistent with the primary mode of interaction via the histone fold of H3-H4, obscured by DNA in the nucleosome. Mutation of a conserved arginine (Arg-42) on the MEP50 insertion loop impaired the PRMT5-MEP50 enzymatic efficiency by increasing its histone substrate Km, comparable with that of Caenorhabditis elegans PRMT5. We show that PRMT5-MEP50 prefers unmethylated substrates, consistent with a distributive model for dimethylation and suggesting discrete biological roles for mono- and dimethylarginine-modified proteins. We propose a model in which MEP50 and PRMT5 simultaneously engage the protein substrate, orienting its targeted arginine to the catalytic site.
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Affiliation(s)
- Emmanuel S Burgos
- From the Department of Biochemistry, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461 and
| | - Carola Wilczek
- From the Department of Biochemistry, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461 and
| | - Takashi Onikubo
- From the Department of Biochemistry, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461 and
| | - Jeffrey B Bonanno
- From the Department of Biochemistry, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461 and
| | - Janina Jansong
- JPT Peptide Technologies GmbH, Volmerstrasse 5, 12489 Berlin, Germany
| | - Ulf Reimer
- JPT Peptide Technologies GmbH, Volmerstrasse 5, 12489 Berlin, Germany
| | - David Shechter
- From the Department of Biochemistry, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461 and
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Wang WL, Anderson LC, Nicklay JJ, Chen H, Gamble MJ, Shabanowitz J, Hunt DF, Shechter D. Phosphorylation and arginine methylation mark histone H2A prior to deposition during Xenopus laevis development. Epigenetics Chromatin 2014; 7:22. [PMID: 25302076 PMCID: PMC4191874 DOI: 10.1186/1756-8935-7-22] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 08/14/2014] [Indexed: 01/21/2023] Open
Abstract
Background Stored, soluble histones in eggs are essential for early development, in particular during the maternally controlled early cell cycles in the absence of transcription. Histone post-translational modifications (PTMs) direct and regulate chromatin-templated transactions, so understanding the nature and function of pre-deposition maternal histones is essential to deciphering mechanisms of regulation of development, chromatin assembly, and transcription. Little is known about histone H2A pre-deposition modifications nor known about the transitions that occur upon the onset of zygotic control of the cell cycle and transcription at the mid-blastula transition (MBT). Results We isolated histones from staged Xenopus laevis oocytes, eggs, embryos, and assembled pronuclei to identify changes in histone H2A modifications prior to deposition and in chromatin. Soluble and chromatin-bound histones from eggs and embryos demonstrated distinct patterns of maternal and zygotic H2A PTMs, with significant pre-deposition quantities of S1ph and R3me1, and R3me2s. We observed the first functional distinction between H2A and H4 S1 phosphorylation, as we showed that H2A and H2A.X-F (also known as H2A.X.3) serine 1 (S1) is phosphorylated concomitant with germinal vesicle breakdown (GVBD) while H4 serine 1 phosphorylation occurs post-MBT. In egg extract H2A/H4 S1 phosphorylation is independent of the cell cycle, chromatin assembly, and DNA replication. H2AS1ph is highly enriched on blastula chromatin during repression of zygotic gene expression while H4S1ph is correlated with the beginning of maternal gene expression and the lengthening of the cell cycle, consistent with distinct biological roles for H2A and H4 S1 phosphorylation. We isolated soluble H2A and H2A.X-F from the egg and chromatin-bound in pronuclei and analyzed them by mass spectrometry analysis to quantitatively determine abundances of S1ph and R3 methylation. We show that H2A and H4 S1ph, R3me1 and R3me2s are enriched on nucleosomes containing both active and repressive histone PTMs in human A549 cells and Xenopus embryos. Conclusions Significantly, we demonstrated that H2A phosphorylation and H4 arginine methylation form a new class of bona fide pre-deposition modifications in the vertebrate embryo. We show that S1ph and R3me containing chromatin domains are not correlated with H3 regulatory PTMs, suggesting a unique role for phosphorylation and arginine methylation.
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Affiliation(s)
- Wei-Lin Wang
- Department of Biochemistry, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY 10461, USA
| | - Lissa C Anderson
- Department of Chemistry, Health Sciences Center, University of Virginia, Charlottesville, VA 22904, USA
| | - Joshua J Nicklay
- Department of Chemistry, Health Sciences Center, University of Virginia, Charlottesville, VA 22904, USA
| | - Hongshan Chen
- Department of Molecular Pharmacology, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY 10461, USA
| | - Matthew J Gamble
- Department of Molecular Pharmacology, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY 10461, USA
| | - Jeffrey Shabanowitz
- Department of Chemistry, Health Sciences Center, University of Virginia, Charlottesville, VA 22904, USA
| | - Donald F Hunt
- Department of Chemistry, Health Sciences Center, University of Virginia, Charlottesville, VA 22904, USA ; Department of Pathology, Health Sciences Center, University of Virginia, Charlottesville, VA 22904, USA
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY 10461, USA
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Shechter D. Seeing beyond the double helix. J Pediatr Ophthalmol Strabismus 2014; 51:268. [PMID: 25291156 DOI: 10.3928/01913913-20140819-06] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Wang WL, Nicklay JJ, Anderson L, Strukl J, Onikubo T, Shabanowitz J, Hunt DF, Shechter D. Developmental regulation of histone H2A deposition via serine-1 phosphorylation. Epigenetics Chromatin 2013. [PMCID: PMC3600798 DOI: 10.1186/1756-8935-6-s1-p74] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Wilczek C, Chitta R, Woo E, Shabanowitz J, Chait BT, Hunt DF, Shechter D. Protein arginine methyltransferase Prmt5-Mep50 methylates histones H2A and H4 and the histone chaperone nucleoplasmin in Xenopus laevis eggs. J Biol Chem 2011; 286:42221-42231. [PMID: 22009756 PMCID: PMC3234966 DOI: 10.1074/jbc.m111.303677] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 10/17/2011] [Indexed: 12/20/2022] Open
Abstract
Histone proteins carry information contained in post-translational modifications. Eukaryotic cells utilize this histone code to regulate the usage of the underlying DNA. In the maturing oocytes and eggs of the frog Xenopus laevis, histones are synthesized in bulk in preparation for deposition during the rapid early developmental cell cycles. During this key developmental time frame, embryonic pluripotent chromatin is established. In the egg, non-chromatin-bound histones are complexed with storage chaperone proteins, including nucleoplasmin. Here we describe the identification and characterization of a complex of the protein arginine methyltransferase 5 (Prmt5) and the methylosome protein 50 (Mep50) isolated from Xenopus eggs that specifically methylates predeposition histones H2A/H2A.X-F and H4 and the histone chaperone nucleoplasmin on a conserved motif (GRGXK). We demonstrate that nucleoplasmin (Npm), an exceedingly abundant maternally deposited protein, is a potent substrate for Prmt5-Mep50 and is monomethylated and symmetrically dimethylated at Arg-187. Furthermore, Npm modulates Prmt5-Mep50 activity directed toward histones, consistent with a regulatory role for Npm in vivo. We show that H2A and nucleoplasmin methylation appears late in oogenesis and is most abundant in the laid egg. We hypothesize that these very abundant arginine methylations are constrained to pre-mid blastula transition events in the embryo and therefore may be involved in the global transcriptional repression found in this developmental time frame.
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Affiliation(s)
- Carola Wilczek
- Department of Biochemistry, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461
| | - Raghu Chitta
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904
| | - Eileen Woo
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, Rockefeller University, New York, New York 10065
| | - Jeffrey Shabanowitz
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, Rockefeller University, New York, New York 10065
| | - Donald F Hunt
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904
| | - David Shechter
- Department of Biochemistry, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461.
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Abstract
PURPOSE The pharmacologic properties, clinical efficacy, and safety profile of the injectable agent denosumab for the treatment of postmenopausal women with osteoporosis are reviewed. SUMMARY Denosumab, a human monoclonal antibody that targets a key protein mediator of bone resorption, was approved by the Food and Drug Administration in June 2010 for the treatment of postmenopausal women with osteoporosis who are at high risk for fracture, including "patients who have failed or are intolerant to other available osteoporosis therapy." Available in a 60-mg prefilled syringe, denosumab should be administered subcutaneously by a health care professional at six-month intervals. In Phase III clinical efficacy trials involving nearly 10,000 postmenopausal women, the use of denosumab was associated with a number of significant benefits: reduced bone resorption, increased bone mass, and reduced rates of vertebral, nonvertebral, and hip fractures. Results of two comparison studies indicated that denosumab therapy increased bone mineral density (BMD) at various skeletal sites to a significantly greater extent than alendronate therapy. In the largest clinical trial of the drug to date, adverse effects occurring significantly more often with denosumab versus placebo included eczema-related effects and cellulitis; long-term safety evaluations are ongoing. CONCLUSION Denosumab has been shown to decrease bone resorption; increase BMD at all skeletal sites measured; and significantly reduce rates of vertebral, nonvertebral, and hip fractures in postmenopausal women with osteoporosis. Denosumab appears to have a favorable risk:benefit profile and provides a new treatment option for many patients in this population.
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Affiliation(s)
- Mona Chitre
- Clinical Services, Strategy and Policy, Excellus BlueCross BlueShield, Rochester, NY 14647, USA.
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Banaszynski LA, Allis CD, Shechter D. Analysis of histones and chromatin in Xenopus laevis egg and oocyte extracts. Methods 2010; 51:3-10. [PMID: 20051265 PMCID: PMC2868095 DOI: 10.1016/j.ymeth.2009.12.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Revised: 12/14/2009] [Accepted: 12/30/2009] [Indexed: 11/18/2022] Open
Abstract
Histones are the major protein components of chromatin, the physiological form of the genome in all eukaryotic cells. Chromatin is the substrate of information-directed biological processes, such as gene regulation and transcription, replication, and mitosis. A long-standing experimental model system to study many of these processes is the extract made from the eggs of the anuran Xenopus laevis. Since work in recent years has solidified the importance of post-translational modification of histones in directing biological processes, the study of histones in a biochemically dissectible model such as Xenopus is crucial for the understanding of their biological significance. Here we present a rationale and methods for isolating and studying histones and chromatin in different Xenopus egg and oocyte extracts. In particular, we present protocols for the preparation of: cell-free egg and oocyte extract; nucleoplasmic extract ("NPE"); biochemical purification of maternally-deposited, stored histones in the oocyte and the egg; assembly of pronuclei in egg extract and the isolation of pronuclear chromatin and histones; and an extract chromatin assembly assay. We also demonstrate aspects of the variability of the system to be mindful of when working with extract and the importance of proper laboratory temperature in preparing quality extracts. We expect that these methods will be of use in promoting further understanding of embryonic chromatin in a unique experimental system.
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Affiliation(s)
- Laura A. Banaszynski
- The Laboratory of Chromatin Biology, The Rockefeller University, New York, NY, USA
| | - C. David Allis
- The Laboratory of Chromatin Biology, The Rockefeller University, New York, NY, USA
| | - David Shechter
- The Laboratory of Chromatin Biology, The Rockefeller University, New York, NY, USA
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461
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Xiao A, Li H, Shechter D, Ahn SH, Fabrizio LA, Erdjument-Bromage H, Ishibe-Murakami S, Wang B, Tempst P, Hofmann K, Patel DJ, Elledge SJ, Allis CD. WSTF regulates the H2A.X DNA damage response via a novel tyrosine kinase activity. Nature 2008; 457:57-62. [PMID: 19092802 PMCID: PMC2854499 DOI: 10.1038/nature07668] [Citation(s) in RCA: 303] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Accepted: 11/27/2008] [Indexed: 12/20/2022]
Abstract
DNA double-stranded breaks present a serious challenge for eukaryotic cells. The inability to repair breaks leads to genomic instability, carcinogenesis and cell death. During the double-strand break response, mammalian chromatin undergoes reorganization demarcated by H2A.X Ser 139 phosphorylation (gamma-H2A.X). However, the regulation of gamma-H2A.X phosphorylation and its precise role in chromatin remodelling during the repair process remain unclear. Here we report a new regulatory mechanism mediated by WSTF (Williams-Beuren syndrome transcription factor, also known as BAZ1B)-a component of the WICH complex (WSTF-ISWI ATP-dependent chromatin-remodelling complex). We show that WSTF has intrinsic tyrosine kinase activity by means of a domain that shares no sequence homology to any known kinase fold. We show that WSTF phosphorylates Tyr 142 of H2A.X, and that WSTF activity has an important role in regulating several events that are critical for the DNA damage response. Our work demonstrates a new mechanism that regulates the DNA damage response and expands our knowledge of domains that contain intrinsic tyrosine kinase activity.
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Affiliation(s)
- Andrew Xiao
- Laboratory of Chromatin Biology, The Rockefeller University, New York, New York 10065, USA
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Shechter D, Nicklay JJ, Chitta RK, Shabanowitz J, Hunt DF, Allis CD. Analysis of histones in Xenopus laevis. I. A distinct index of enriched variants and modifications exists in each cell type and is remodeled during developmental transitions. J Biol Chem 2008; 284:1064-74. [PMID: 18957438 DOI: 10.1074/jbc.m807273200] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Histone proteins contain epigenetic information that is encoded both in the relative abundance of core histones and variants and particularly in the post-translational modification of these proteins. We determined the presence of such variants and covalent modifications in seven tissue types of the anuran Xenopus laevis, including oocyte, egg, sperm, early embryo equivalent (pronuclei incubated in egg extract), S3 neurula cells, A6 kidney cells, and erythrocytes. We first developed a new robust method for isolating the stored, predeposition histones from oocytes and eggs via chromatography on heparin-Sepharose, whereas we isolated chromatinized histones via conventional acid extraction. We identified two previously unknown H1 isoforms (H1fx and H1B.Sp) present on sperm chromatin. We immunoblotted this global collection of histones with many specific post-translational modification antibodies, including antibodies against methylated histone H3 on Lys(4), Lys(9), Lys(27), Lys(79), Arg(2), Arg(17), and Arg(26); methylated histone H4 on Lys(20); methylated H2A and H4 on Arg(3); acetylated H4 on Lys(5), Lys(8), Lys(12), and Lys(16) and H3 on Lys(9) and Lys(14); and phosphorylated H3 on Ser(10) and H2A/H4 on Ser(1). Furthermore, we subjected a subset of these histones to two-dimensional gel analysis and subsequent immunoblotting and mass spectrometry to determine the global remodeling of histone modifications that occurs as development proceeds. Overall, our observations suggest that each metazoan cell type may have a unique histone modification signature correlated with its differentiation status.
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Affiliation(s)
- David Shechter
- Laboratory of Chromatin Biology, The Rockefeller University, New York, New York 10065, USA
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Nicklay JJ, Shechter D, Chitta RK, Garcia BA, Shabanowitz J, Allis CD, Hunt DF. Analysis of histones in Xenopus laevis. II. mass spectrometry reveals an index of cell type-specific modifications on H3 and H4. J Biol Chem 2008; 284:1075-85. [PMID: 18957437 DOI: 10.1074/jbc.m807274200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Epigenetic information is hypothesized to be encoded in histone variants and post-translational modifications. Varied cell- and locus-specific combinations of these epigenetic marks are likely contributors to regulation of chromatin-templated transactions, including transcription, replication, recombination, and repair. Therefore, the relative abundance of histone modifications in a given cell type is a potential index of cell fate and specificity. Here, we utilize mass spectrometry techniques to characterize the relative abundance index of cell type-specific modifications on histones H3 and H4 in distinct cell types from the frog Xenopus laevis, including the sperm, the stored predeposition histones in the egg, the early embryo equivalent pronuclei, cultured somatic cells, and erythrocytes. We used collisionally associated dissociation to identify the modifications present on histone H3 in a variety of cell types, resolving 26 distinctly modified H3 peptides. We employed the electron transfer dissociation fragmentation technique in a "middle-down" approach on the H4 N-terminal tail to explore the overlap of post-translational modifications. We observed 66 discrete isoforms of the H4 1-23 fragment in four different cell types. Isolation of the stored, predeposition histone H4 from the frog egg also revealed a more varied pattern of modifications than the previously known diacetylation on Lys(5) and Lys(12). The developmental transitions of modifications on H3 and H4 were strikingly varied, implying a strong correlation of the histone code with cell type and fate. Our results are consistent with a histone code index for each cell type and uncover potential cross-talk between modifications on a single tail.
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Affiliation(s)
- Joshua J Nicklay
- Laboratory of Chromatin Biology, The Rockefeller University, New York, New York 10065, USA
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30
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Abstract
Histone proteins are the major protein components of chromatin, the physiologically relevant form of the genome (or epigenome) in all eukaryotic cells. Chromatin is the substrate of many biological processes, such as gene regulation and transcription, replication, mitosis and apoptosis. Since histones are extensively post-translationally modified, the identification of these covalent marks on canonical and variant histones is crucial for the understanding of their biological significance. Many different biochemical techniques have been developed to purify and separate histone proteins. Here, we present standard protocols for acid extraction and salt extraction of histones from chromatin; separation of extracted histones by reversed-phase HPLC; analysis of histones and their specific post-translational modification profiles by acid urea (AU) gel electrophoresis and the additional separation of non-canonical histone variants by triton AU(TAU) and 2D TAU electrophoresis; and immunoblotting of isolated histone proteins with modification-specific antibodies.
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Affiliation(s)
- David Shechter
- The Laboratory of Chromatin Biology, The Rockefeller University, New York, NY, USA
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31
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Goetzel RZ, Reynolds K, Breslow L, Roper WL, Shechter D, Stapleton DC, Lapin PJ, McGinnis JM. Health promotion in later life: it's never too late. Am J Health Promot 2007; 21:1-5, iii. [PMID: 17375496 DOI: 10.4278/0890-1171-21.4.tahp-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [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: 11/17/2022]
Abstract
The clinical and epidemiological rationale for the health improvement benefits of health promotion in the later years of life are provided in this article. The authors review the emerging scientific consensus concerning the utility of lifestyle interventions for health improvement in the context of a narrowed definition of health promotion. Governmental initiatives for testing health promotion among Medicare beneficiaries are also discussed. Major research findings are reviewed and implications for health promotion practioners are also provided.
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Goetzel RZ, Shechter D, Ozminkowski RJ, Marmet PF, Tabrizi MJ, Roemer EC. Promising Practices in Employer Health and Productivity Management Efforts: Findings From a Benchmarking Study. J Occup Environ Med 2007; 49:111-30. [PMID: 17293753 DOI: 10.1097/jom.0b013e31802ec6a3] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.4] [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: 11/25/2022]
Abstract
OBJECTIVE To identify key success factors related to employer-based health and productivity management (HPM) programs. METHODS Data regarding promising practices in HPM were gathered via literature review, discussions with subject matter experts, online inventory, and site visits. RESULTS Promising practices in HPM include 1) integrating HPM programs into the organization's operations; 2) simultaneously addressing individual, environmental, policy, and cultural factors affecting health and productivity; 3) targeting several health issues; 4) tailoring programs to address specific needs; 5) attaining high participation; 6) rigorously evaluating programs; and 7) communicating successful outcomes to key stakeholders. CONCLUSION Increased efforts should be directed at disseminating the experiences of promising practices. However, more research is needed in this area, so that additional public and private funding is made available for applied research in "real-life" business settings. Finally, employers should be provided effective tools and resources to support their HPM efforts.
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Affiliation(s)
- Ron Z Goetzel
- Institute for Health and Productivity Studies, Cornell University, Washington DC 20008, USA.
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Abstract
The impact of an aging population on escalating US healthcare costs is influenced largely by the prevalence of chronic disease in this population. Consequently, preventing or postponing disease onset among the elderly has become a crucial public health issue. Fortunately, much of the total burden of disease is attributable to conditions that are preventable. In this paper, we address whether well-designed health promotion programs can prevent illness, reduce disability, and improve the quality of life. Furthermore, we assess evidence that these programs have the potential to reduce healthcare utilization and related expenditures for the Medicare program. We hypothesize that seniors who reduce their modifiable health risks can forestall disability, reduce healthcare utilization, and save Medicare money. We end with a discussion of a new Senior Risk Reduction Demonstration, which will be initiated by the Centers for Medicare and Medicaid Services in 2007, to test whether risk reduction programs developed in the private sector can achieve health improvements among seniors and a positive return on investment for the Medicare program.
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Affiliation(s)
- Ron Z Goetzel
- Institute for Health and Productivity Studies, Cornell University Washington, DC 20008, USA.
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Ozminkowski RJ, Goetzel RZ, Wang F, Gibson TB, Shechter D, Musich S, Bender J, Edington DW. The Savings Gained From Participation in Health Promotion Programs for Medicare Beneficiaries. J Occup Environ Med 2006; 48:1125-32. [PMID: 17099448 DOI: 10.1097/01.jom.0000240709.01860.8a] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [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: 11/25/2022]
Abstract
OBJECTIVE The objective of this study was to estimate savings to Medicare associated with participation in one or more health promotion programs offered to 59,324 retirees from a large employer and their aged dependents. METHODS Propensity score and multiple regression techniques were used to estimate savings adjusted for demographic and health status differences between elderly retirees and dependents who used one or more health promotion services and nonparticipants. RESULTS Participants who completed a health risk assessment saved from $101 to $648 per person per year. Savings were generally higher as more programs were used, but differences were not always statistically significant. CONCLUSION Using the health risk assessment as a guide for health promotion programs can yield substantial savings for the elderly and the Medicare program. The federal government should test health promotion programs in randomized trials and pay for such programs if the results suggest cost savings and better health for Medicare beneficiaries.
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Affiliation(s)
- Ronald J Ozminkowski
- Health and Productivity Research, Thomson Medstat and the Institute for Health and Productivity Studies, Cornell University, 777 East Eisenhower Parkway 903R, Ann Arbor, MI 48108, USA.
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Ozminkowski RJ, Goetzel RZ, Shechter D, Stapleton DC, Baser O, Lapin P. Predictors of preventive service use among Medicare beneficiaries. Health Care Financ Rev 2006; 27:5-23. [PMID: 17290645 PMCID: PMC4194948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Despite Medicare coverage, receipt of clinical preventive services is suboptimal. Using multivariate regression analyses and Medicare Current Beneficiary Survey (MCBS) data for 2001, we estimated the relationship between the number of preventive services received in the 12-month recall period and: socioeconomics, plan type, health status, health risks, and ability to address daily needs. Results are nationally representative for the study year. With the exception of blood pressure and cholesterol screening, approximately one- to two-thirds of Medicare beneficiaries did not receive recommended preventive services. Strategies should be developed to ensure appropriate use of preventive services over time.
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Abstract
The nuclear protein kinase ATR controls S-phase progression in response to DNA damage and replication fork stalling, including damage caused by ultraviolet irradiation, hyperoxia, and replication inhibitors like aphidicolin and hydroxyurea. ATR activation and substrate specificity require the presence of adapter and mediator molecules, ultimately resulting in the downstream inhibition of the S-phase kinases that function to initiate DNA replication at origins of replication. The data reviewed strongly support the hypothesis that ATR is activated in response to persistent RPA-bound single-stranded DNA, a common intermediate of unstressed and damaged DNA replication and metabolism.
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Affiliation(s)
- David Shechter
- Department of Genetics and Development, Hammer Health Sciences Center, Room 1620, Columbia University College of Physicians and Surgeons, 701 W. 168th Street, New York, NY 10032, USA.
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Shechter D, Gautier J. ATM and ATR check in on origins: a dynamic model for origin selection and activation. Cell Cycle 2005; 4:235-8. [PMID: 15655372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023] Open
Abstract
Initiation of DNA replication occurs at origins of replication, traditionally defined by specific sequence elements. Sequence-dependent initiation of replication is the rule in prokaryotes and in the yeast Saccharomyces cereviseae. However, sequence-dependent initiation does not appear to be absolutely required in metazoan eukaryotes. Origin firing is instead likely dependent on stochastic initiation from chromatin-defined loci, despite the demonstration of some specific origins. Based on some recent observations in Xenopus laevis egg extracts and in mammalian cell culture, we propose that timing of origin firing is dependent on feedback from active replicons. This dynamic regulation of replication is mediated by sensing of ongoing replication by the DNA-damage checkpoint kinases ATM and ATR, which in turn downregulate neighboring and distal origins and replicons by inhibition of the S-phase kinases Cdk2 and Cdc7 and by inhibition of the replicative Mcm helicase. Origin selection, activation, and replicon progression are therefore constrained in both space and time via feedback from the cell cycle and ongoing replication.
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Affiliation(s)
- David Shechter
- Integrated Program in Cellular, Molecular, and Biophysical Studies, Department of Genetics and Development, Hammer Health Sciences Center, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
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Abstract
Minichromosome maintenance proteins (Mcm) are essential in all eukaryotes and are absolutely required for initiation of DNA replication. The eukaryotic and archaeal Mcm proteins have conserved helicase motifs and exhibit DNA helicase and ATP hydrolysis activities in vitro. Although the Mcm proteins have been proposed to be the replicative helicase, the enzyme that melts the DNA helix at the replication fork, their function during cellular DNA replication elongation is still unclear. Using nucleoplasmic extract (NPE) from Xenopus laevis eggs and six purified polyclonal antibodies generated against each of the Xenopus Mcm proteins, we have demonstrated that Mcm proteins are required during DNA replication and DNA unwinding after initiation of replication. Quantitative depletion of Mcms from the NPE results in normal replication and unwinding, confirming that Mcms are required before pre-replicative complex assembly and dispensable thereafter. Replication and unwinding are inhibited when pooled neutralizing antibodies against the six different Mcm2-7 proteins are added during NPE incubation. Furthermore, replication is blocked by the addition of the Mcm antibodies after an initial period of replication in the NPE, visualized by a pulse of radiolabeled nucleotide at the same time as antibody addition. Addition of the cyclin-dependent kinase 2 inhibitor p21(cip1) specifically blocks origin firing but does not prevent helicase action. When p21(cip1) is added, followed by the non-hydrolyzable analog ATPgammaS to block helicase function, unwinding is inhibited, demonstrating that plasmid unwinding is specifically attributable to an ATP hydrolysis-dependent function. These data support the hypothesis that the Mcm protein complex functions as the replicative helicase.
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Affiliation(s)
- David Shechter
- Integrated Program in Cellular, Molecular, and Biophysical Studies, Department of Genetics and Development, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
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Affiliation(s)
- David Shechter
- Department of Genetics and Development, Columbia University, 701 West 168th Street, New York, NY 10032
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Shechter D, Costanzo V, Gautier J. ATR and ATM regulate the timing of DNA replication origin firing. Nat Cell Biol 2004; 6:648-55. [PMID: 15220931 DOI: 10.1038/ncb1145] [Citation(s) in RCA: 346] [Impact Index Per Article: 17.3] [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] [Received: 05/05/2004] [Accepted: 06/01/2004] [Indexed: 11/10/2022]
Abstract
Timing of DNA replication initiation is dependent on S-phase-promoting kinase (SPK) activity at discrete origins and the simultaneous function of many replicons. DNA damage prevents origin firing through the ATM- and ATR-dependent inhibition of Cdk2 and Cdc7 SPKs. Here, we establish that modulation of ATM- and ATR-signalling pathways controls origin firing in the absence of DNA damage. Inhibition of ATM and ATR with caffeine or specific neutralizing antibodies, or upregulation of Cdk2 or Cdc7, promoted rapid and synchronous origin firing; conversely, inhibition of Cdc25A slowed DNA replication. Cdk2 was in equilibrium between active and inactive states, and the concentration of replication protein A (RPA)-bound single-stranded DNA (ssDNA) correlated with Chk1 activation and inhibition of origin firing. Furthermore, ATM was transiently activated during ongoing replication. We propose that ATR and ATM regulate SPK activity through a feedback mechanism originating at active replicons. Our observations establish that ATM- and ATR-signalling pathways operate during an unperturbed cell cycle to regulate initiation and progression of DNA synthesis, and are therefore poised to halt replication in the presence of DNA damage.
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Affiliation(s)
- David Shechter
- Integrated Program in Cellular, Molecular, and Biophysical Studies, and Department of Genetics and Development, Hammer Health Sciences Center, Columbia University College of Physicians and Surgeons, 701 West 168th Street, New York, NY 10032, USA
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Costanzo V, Shechter D, Lupardus PJ, Cimprich KA, Gottesman M, Gautier J. An ATR- and Cdc7-dependent DNA damage checkpoint that inhibits initiation of DNA replication. Mol Cell 2003; 11:203-13. [PMID: 12535533 DOI: 10.1016/s1097-2765(02)00799-2] [Citation(s) in RCA: 334] [Impact Index Per Article: 15.9] [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: 11/18/2022]
Abstract
We have analyzed how single-strand DNA gaps affect DNA replication in Xenopus egg extracts. DNA lesions generated by etoposide, a DNA topoisomerase II inhibitor, or by exonuclease treatment activate a DNA damage checkpoint that blocks initiation of plasmid and chromosomal DNA replication. The checkpoint is abrogated by caffeine and requires ATR, but not ATM, protein kinase. The block to DNA synthesis is due to inhibition of Cdc7/Dbf4 protein kinase activity and the subsequent failure of Cdc45 to bind to chromatin. The checkpoint does not require pre-RC assembly but requires loading of the single-strand binding protein, RPA, on chromatin. This is the biochemical demonstration of a DNA damage checkpoint that targets Cdc7/Dbf4 protein kinase.
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Affiliation(s)
- Vincenzo Costanzo
- Department of Genetics and Development, Columbia University, New York, NY 10032, USA
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Chen S, Shechter D, Chaiken S. Getting at the truth or getting along: Accuracy- versus impression-motivated heuristic and systematic processing. J Pers Soc Psychol 1996. [DOI: 10.1037/0022-3514.71.2.262] [Citation(s) in RCA: 188] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Yao N, Turner J, Kelman Z, Stukenberg PT, Dean F, Shechter D, Pan ZQ, Hurwitz J, O'Donnell M. Clamp loading, unloading and intrinsic stability of the PCNA, beta and gp45 sliding clamps of human, E. coli and T4 replicases. Genes Cells 1996; 1:101-13. [PMID: 9078370 DOI: 10.1046/j.1365-2443.1996.07007.x] [Citation(s) in RCA: 165] [Impact Index Per Article: 5.9] [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: 02/04/2023]
Abstract
BACKGROUND The high speed and processivity of replicative DNA polymerases reside in a processivity factor which has been shown to be a ring-shaped protein. This protein ("sliding clamp') encircles DNA and tethers the catalytic unit to the template. Although in eukaryotic, prokaryotic and bacteriophage-T4 systems, the processivity factors are ring-shaped, they assume different oligomeric states. The Escherichia coli clamp (the beta subunit) is active as a dimer while the eukaryotic and T4 phage clamps (PCNA and gp45, respectively) are active as trimers. The clamp can not assemble itself on DNA. Instead, a protein complex known as a clamp loader utilizes ATP to assemble the ring around the primer-template. This study compares properties of the human PCNA clamp with those of E. coli and T4 phage. RESULTS The PCNA ring is a stable trimer down to a concentration below 100 nM (Kd approximately 21 nM). On DNA, the PCNA clamp slides freely and dissociates from DNA slowly (t1/2 approximately 24 min). beta is more stable in solution (Kd < 60 PM) and on DNA (t1/2 approximately 1 h) than PCNA which may be explained by its simpler oligomeric state. The T4 gp45 clamp is a much less stable trimer than PCNA (Kd approximately 250 nM) and requires association with the polymerase to stabilize it on DNA as observed previously. The consequence of this cooperation between clamp and polymerase is that upon finishing a template and dissociation of the polymerase from DNA, the gp45 clamp spontaneously dissociates from DNA without assistance. However, the greater stability of the PCNA and beta clamps on DNA necessitates an active process for their removal. The clamp loaders (RFC and gamma complex) were also capable of unloading their respective clamps from DNA in the presence of ATP. CONCLUSIONS The stability of the different clamps in solution correlates with their stability on DNA. Thus, the low stability of the T4 clamp explains the inability to isolate gp45 on DNA. The stability of the PCNA and beta clamps predicts they will require an unloading factor to recycle them on and off DNA during replication. The clamp loaders of PCNA and beta double as clamp unloaders presumably for the purpose of clamp recycling.
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Affiliation(s)
- N Yao
- Microbiology Department, Howard Hughes Medical Institute, Cornell University Medical College, New York, NY 10021, USA
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Shechter D, Radnay J, Yochay Y, Kott E. Copaxone effect over the number of CD8,CD4,CD3 T cells, CD19 B cells and NK cells CD56+CD3-before and during treatment. J Neuroimmunol 1995. [DOI: 10.1016/0165-5728(95)99029-i] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Okun S, Mehl S, DellaCorte M, Shechter D, Esposito F. The use of prophylactic antibiotics in clean podiatric surgery. J Foot Surg 1984; 23:402-6. [PMID: 6501801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The presence of a postoperative wound infection after clean podiatric surgery may predispose the patient to a prolonged, often nonambulatory, convalescent period. Although the incidence of postoperative infection after elective podiatric surgery is small, a protocol to govern the use of prophylactic antibiotics has been developed in order to achieve their maximum benefits with a minimum of risk. Indications for chemoprophylaxis have been divided into two groups: specific operative procedures that may warrant antibiotic intervention and patients who present with specific risk factors. Additionally, it has been suggested that single dose prophylaxis is preferable to multiple dose administration.
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