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Almalki NAR, Sabir JSM, Ibrahim A, Alhosin M, Asseri AH, Albiheyri RS, Zari AT, Bahieldin A, Javed A, Mély Y, Hamiche A, Mousli M, Bronner C. UHRF1 poly-auto-ubiquitination induced by the anti-cancer drug, thymoquinone, is involved in the DNA repair machinery recruitment. Int J Biochem Cell Biol 2024; 171:106582. [PMID: 38649007 DOI: 10.1016/j.biocel.2024.106582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 03/20/2024] [Accepted: 04/16/2024] [Indexed: 04/25/2024]
Abstract
DNA methylation is one of the most important epigenetic mark involved in many physiologic cellular processes and pathologies. During mitosis, the transmission of DNA methylation patterns from a mother to the daughter cells is ensured through the action of the Ubiquitin-like, containing PHD and RING domains, 1/DNA methyltransferase 1 (UHRF1/DNMT1) tandem. UHRF1 is involved in the silencing of many tumor suppressor genes (TSGs) via mechanisms that remain largely to be deciphered. The present study investigated the role and the regulation of UHRF1 poly-ubiquitination induced by thymoquinone, a natural anti-cancer drug, known to enhance or re-activate the expression of TSGs. We found that the auto-ubiquitination of UHRF1, induced by TQ, is mediated by reactive oxygen species, and occurs following DNA damage. We demonstrated that the poly-ubiquitinated form of UHRF1 is K63-linked and can still silence the tumor suppressor gene p16INK4A/CDKN2A. We further showed that TQ-induced auto-ubiquitination is mediated via the activity of Tip60. Since this latter is known as a nuclear receptor co-factor, we investigated if the glucocorticoid receptor (GR) might be involved in the regulation of UHRF1 ubiquitination. Activation of the GR, with dexamethasone, did not influence auto-ubiquitination of UHRF1. However, we could observe that TQ induced a K48-linked poly-ubiquitination of GR, probably involved in the proteosomal degradation pathway. Mass-spectrometry analysis of FLAG-HA-tagged UHRF1 identified UHRF1 partners involved in DNA repair and showed that TQ increased their association with UHRF1, suggesting that poly-ubiquitination of UHRF1 is involved in the DNA repair process. We propose that poly-ubiquitination of UHRF1 serves as a scaffold to recruit the DNA repair machinery at DNA damage sites.
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Affiliation(s)
- Naif A R Almalki
- Department of Functional Genomics, Institute of Genetics and Molecular and Cellular Biology (IGBMC), INSERM U1258, CNRS UMR 7104, University of Strasbourg, "équipe labellisée" Ligue contre le Cancer, Illkirch-Graffenstaden 67404, France; Experimental Biochemistry unit, King Fahad medical research Centre, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Jamal S M Sabir
- Department of Biological Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia; Centre of Excellence in Bionanoscience, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Abdulkhaleg Ibrahim
- Department of Functional Genomics, Institute of Genetics and Molecular and Cellular Biology (IGBMC), INSERM U1258, CNRS UMR 7104, University of Strasbourg, "équipe labellisée" Ligue contre le Cancer, Illkirch-Graffenstaden 67404, France; National Research Centre for Tropical and Transboundary Diseases (NRCTTD), Alzentan 99316, Libya
| | - Mahmoud Alhosin
- Department of Biochemistry, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Amer H Asseri
- Department of Biochemistry, King Abdulaziz University, Jeddah 21589, Saudi Arabia; Centre for Artificial Intelligence in Precision Medicines, King Abdul-Aziz University, Jeddah 21589, Saudi Arabia
| | - Raed S Albiheyri
- Department of Biological Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia; Centre of Excellence in Bionanoscience, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ali T Zari
- Department of Biological Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia; Centre of Excellence in Bionanoscience, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ahmed Bahieldin
- Department of Biological Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia; Centre of Excellence in Bionanoscience, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Aqib Javed
- Laboratory of Bioimaging and Pathologies, UMR 7021 CNRS, University of Strasbourg, Faculty of Pharmacy, Illkirch-Graffenstaden 67401, France
| | - Yves Mély
- Laboratory of Bioimaging and Pathologies, UMR 7021 CNRS, University of Strasbourg, Faculty of Pharmacy, Illkirch-Graffenstaden 67401, France
| | - Ali Hamiche
- Department of Functional Genomics, Institute of Genetics and Molecular and Cellular Biology (IGBMC), INSERM U1258, CNRS UMR 7104, University of Strasbourg, "équipe labellisée" Ligue contre le Cancer, Illkirch-Graffenstaden 67404, France; Centre of Excellence in Bionanoscience, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Marc Mousli
- Laboratory of Bioimaging and Pathologies, UMR 7021 CNRS, University of Strasbourg, Faculty of Pharmacy, Illkirch-Graffenstaden 67401, France
| | - Christian Bronner
- Department of Functional Genomics, Institute of Genetics and Molecular and Cellular Biology (IGBMC), INSERM U1258, CNRS UMR 7104, University of Strasbourg, "équipe labellisée" Ligue contre le Cancer, Illkirch-Graffenstaden 67404, France.
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Vogt A, He Y, Lees-Miller SP. How to fix DNA breaks: new insights into the mechanism of non-homologous end joining. Biochem Soc Trans 2023; 51:1789-1800. [PMID: 37787023 PMCID: PMC10657183 DOI: 10.1042/bst20220741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 08/26/2023] [Accepted: 09/22/2023] [Indexed: 10/04/2023]
Abstract
Non-homologous end joining (NHEJ) is the major pathway for the repair of ionizing radiation-induced DNA double-strand breaks (DSBs) in human cells and is essential for the generation of mature T and B cells in the adaptive immune system via the process of V(D)J recombination. Here, we review how recently determined structures shed light on how NHEJ complexes function at DNA DSBs, emphasizing how multiple structures containing the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) may function in NHEJ. Together, these studies provide an explanation for how NHEJ proteins assemble to detect and protect DSB ends, then proceed, through DNA-PKcs-dependent autophosphorylation, to a ligation-competent complex.
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Affiliation(s)
- Alex Vogt
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, U.S.A
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, U.S.A
| | - Yuan He
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, U.S.A
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL, U.S.A
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, U.S.A
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Northwestern University, Chicago, U.S.A
| | - Susan P. Lees-Miller
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre and Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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3
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Qin S, Kitty I, Hao Y, Zhao F, Kim W. Maintaining Genome Integrity: Protein Kinases and Phosphatases Orchestrate the Balancing Act of DNA Double-Strand Breaks Repair in Cancer. Int J Mol Sci 2023; 24:10212. [PMID: 37373360 DOI: 10.3390/ijms241210212] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/13/2023] [Accepted: 06/14/2023] [Indexed: 06/29/2023] Open
Abstract
DNA double-strand breaks (DSBs) are the most lethal DNA damages which lead to severe genome instability. Phosphorylation is one of the most important protein post-translation modifications involved in DSBs repair regulation. Kinases and phosphatases play coordinating roles in DSB repair by phosphorylating and dephosphorylating various proteins. Recent research has shed light on the importance of maintaining a balance between kinase and phosphatase activities in DSB repair. The interplay between kinases and phosphatases plays an important role in regulating DNA-repair processes, and alterations in their activity can lead to genomic instability and disease. Therefore, study on the function of kinases and phosphatases in DSBs repair is essential for understanding their roles in cancer development and therapeutics. In this review, we summarize the current knowledge of kinases and phosphatases in DSBs repair regulation and highlight the advancements in the development of cancer therapies targeting kinases or phosphatases in DSBs repair pathways. In conclusion, understanding the balance of kinase and phosphatase activities in DSBs repair provides opportunities for the development of novel cancer therapeutics.
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Affiliation(s)
- Sisi Qin
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
| | - Ichiwa Kitty
- Department of Integrated Biomedical Science, Soonchunhyang Institute of Medi-Bio Science (SIMS), Soonchunhyang University, Cheonan 31151, Chungcheongnam-do, Republic of Korea
| | - Yalan Hao
- Analytical Instrumentation Center, Hunan University, Changsha 410082, China
| | - Fei Zhao
- College of Biology, Hunan University, Changsha 410082, China
| | - Wootae Kim
- Department of Integrated Biomedical Science, Soonchunhyang Institute of Medi-Bio Science (SIMS), Soonchunhyang University, Cheonan 31151, Chungcheongnam-do, Republic of Korea
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Chen S, Vogt A, Lee L, Naila T, McKeown R, Tomkinson AE, Lees-Miller SP, He Y. Cryo-EM visualization of DNA-PKcs structural intermediates in NHEJ. SCIENCE ADVANCES 2023; 9:eadg2838. [PMID: 37256947 PMCID: PMC10413680 DOI: 10.1126/sciadv.adg2838] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 04/28/2023] [Indexed: 06/02/2023]
Abstract
DNA double-strand breaks (DSBs), one of the most cytotoxic forms of DNA damage, can be repaired by the tightly regulated nonhomologous end joining (NHEJ) machinery (Stinson and Loparo and Zhao et al.). Core NHEJ factors form an initial long-range (LR) synaptic complex that transitions into a DNA-PKcs (DNA-dependent protein kinase, catalytic subunit)-free, short-range state to align the DSB ends (Chen et al.). Using single-particle cryo-electron microscopy, we have visualized three additional key NHEJ complexes representing different transition states, with DNA-PKcs adopting distinct dimeric conformations within each of them. Upon DNA-PKcs autophosphorylation, the LR complex undergoes a substantial conformational change, with both Ku and DNA-PKcs rotating outward to promote DNA break exposure and DNA-PKcs dissociation. We also captured a dimeric state of catalytically inactive DNA-PKcs, which resembles structures of other PIKK (Phosphatidylinositol 3-kinase-related kinase) family kinases, revealing a model of the full regulatory cycle of DNA-PKcs during NHEJ.
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Affiliation(s)
- Siyu Chen
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Interdisciplinary Biological Sciences Program, Northwestern University. Evanston, IL, USA
| | - Alex Vogt
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Interdisciplinary Biological Sciences Program, Northwestern University. Evanston, IL, USA
| | - Linda Lee
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre and Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Tasmin Naila
- Department of Internal Medicine and Molecular Genetics and Microbiology and the University of New Mexico Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM, USA
| | - Ryan McKeown
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Interdisciplinary Biological Sciences Program, Northwestern University. Evanston, IL, USA
| | - Alan E Tomkinson
- Department of Internal Medicine and Molecular Genetics and Microbiology and the University of New Mexico Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM, USA
| | - Susan P Lees-Miller
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre and Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Yuan He
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Interdisciplinary Biological Sciences Program, Northwestern University. Evanston, IL, USA
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, USA
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Northwestern University, Chicago, IL, USA
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5
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Jaime-Garza M, Nowotny CA, Coutandin D, Wang F, Tabios M, Agard DA. Hsp90 provides a platform for kinase dephosphorylation by PP5. Nat Commun 2023; 14:2197. [PMID: 37069154 PMCID: PMC10110553 DOI: 10.1038/s41467-023-37659-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 03/23/2023] [Indexed: 04/19/2023] Open
Abstract
The Hsp90 molecular chaperone collaborates with the phosphorylated Cdc37 cochaperone for the folding and activation of its many client kinases. As with many kinases, the Hsp90 client kinase CRaf is activated by phosphorylation at specific regulatory sites. The cochaperone phosphatase PP5 dephosphorylates CRaf and Cdc37 in an Hsp90-dependent manner. Although dephosphorylating Cdc37 has been proposed as a mechanism for releasing Hsp90-bound kinases, here we show that Hsp90 bound kinases sterically inhibit Cdc37 dephosphorylation indicating kinase release must occur before Cdc37 dephosphorylation. Our cryo-EM structure of PP5 in complex with Hsp90:Cdc37:CRaf reveals how Hsp90 both activates PP5 and scaffolds its association with the bound CRaf to dephosphorylate phosphorylation sites neighboring the kinase domain. Thus, we directly show how Hsp90's role in maintaining protein homeostasis goes beyond folding and activation to include post translationally modifying its client kinases.
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Affiliation(s)
- Maru Jaime-Garza
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, 94143, USA
| | - Carlos A Nowotny
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, 94143, USA
| | - Daniel Coutandin
- Novartis Institutes for BioMedical Research, San Diego, CA, 92121, USA
| | - Feng Wang
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, 94143, USA
| | - Mariano Tabios
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, 94143, USA
| | - David A Agard
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, 94143, USA.
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6
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Zhang H, Zhang Q, Tu J, You Q, Wang L. Dual function of protein phosphatase 5 (PPP5C): An emerging therapeutic target for drug discovery. Eur J Med Chem 2023; 254:115350. [PMID: 37054560 DOI: 10.1016/j.ejmech.2023.115350] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/21/2023] [Accepted: 03/28/2023] [Indexed: 04/15/2023]
Abstract
Phosphorylation of proteins is reversibly controlled by the kinases and phosphatases in many posttranslational regulation patterns. Protein phosphatase 5 (PPP5C) is a serine/threonine protein phosphatase showing dual function by simultaneously exerting dephosphorylation and co-chaperone functions. Due to this special role, PPP5C was found to participate in many signal transductions related to various diseases. Abnormal expression of PPP5C results in cancers, obesity, and Alzheimer's disease, making it a potential drug target. However, the design of small molecules targeting PPP5C is struggling due to its special monomeric enzyme form and low basal activity by a self-inhibition mechanism. Through realizing the PPP5C's dual function as phosphatase and co-chaperone, more and more small molecules were found to regulate PPP5C with a different mechanism. This review aims to provide insights into PPP5C's dual function from structure to function, which could provide efficient design strategies for small molecules targeting PPP5C as therapeutic candidates.
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Affiliation(s)
- Hengheng Zhang
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing, 210009, China; Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Qiuyue Zhang
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing, 210009, China; Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Jiaqi Tu
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing, 210009, China; Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, 210009, China
| | - Qidong You
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing, 210009, China; Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, 210009, China.
| | - Lei Wang
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing, 210009, China; Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, 210009, China.
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7
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Tirilomi A, Elakad O, Yao S, Li Y, Hinterthaner M, Danner BC, Ströbel P, Tirilomis T, Bohnenberger H, von Hammerstein-Equord A. Expression and prognostic impact of DNA-PK in human lung cancer. Medicine (Baltimore) 2023; 102:e33143. [PMID: 36862864 PMCID: PMC9981429 DOI: 10.1097/md.0000000000033143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/04/2023] Open
Abstract
Among all cancer patient's lung cancer is the leading cause of death. Prognostic biomarkers continue to be investigated for the detection and stratification of lung cancer for clinical use. The DNA-dependent protein kinase is involved in mechanisms of DNA damage repair. Deregulation and overexpression of DNA-dependent protein kinase is associated with poor prognosis in various tumor entities. In this study, we investigated the expression of DNA-dependent protein kinase in relation to clinicopathological features and overall survival in patients with lung cancer. By immunohistochemistry, expression of DNA-dependent protein kinase was analyzed in 205 cases of lung cancer; 95 cases of adenocarcinoma, 83 cases of squamous cell lung carcinoma and 27 cases of small cell lung cancer and correlated with clinicopathological characteristics as well as patient's overall survival. In patients with adenocarcinoma, a significant correlation between strong expression of DNA-dependent protein kinase and worse overall survival was found. No significant association was observed in patients with squamous cell lung carcinoma and small cell lung cancer. Strong detection of DNA-dependent protein kinase expression was most evident in small cell lung cancer (81.48 %), followed by squamous cell lung carcinoma (62.65 %) and adenocarcinoma (61.05 %). In our study, expression of DNA-dependent protein kinase was associated with poor overall survival in patients with adenocarcinoma. DNA-dependent protein kinase could serve as a new prognostic biomarker.
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Affiliation(s)
- Anna Tirilomi
- Department of Cardio-Thoracic and Vascular Surgery, University Medical Center, Göttingen, Germany
| | - Omar Elakad
- Institute of Pathology, University Medical Center, Göttingen, Germany
| | - Sha Yao
- Institute of Pathology, University Medical Center, Göttingen, Germany
| | - Yuchan Li
- Institute of Pathology, University Medical Center, Göttingen, Germany
| | - Marc Hinterthaner
- Department of Cardio-Thoracic and Vascular Surgery, University Medical Center, Göttingen, Germany
| | - Bernhard C. Danner
- Department of Cardio-Thoracic and Vascular Surgery, University Medical Center, Göttingen, Germany
| | - Philipp Ströbel
- Institute of Pathology, University Medical Center, Göttingen, Germany
| | - Theodor Tirilomis
- Department of Cardio-Thoracic and Vascular Surgery, University Medical Center, Göttingen, Germany
| | | | - Alexander von Hammerstein-Equord
- Department of Cardio-Thoracic and Vascular Surgery, University Medical Center, Göttingen, Germany
- * Correspondence: Alexander von Hammerstein-Equord, Department of Cardio-Thoracic and Vascular Surgery, University Medical Center, Robert-Koch-Str. 40, Göttingen 37075, Germany (e-mail: )
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Fielder SM, Rosenfeld JA, Burrage LC, Emrick L, Lalani S, Attali R, Bembenek JN, Hoang H, Baldridge D, Silverman GA, Schedl T, Pak SC. Functional analysis of a novel de novo variant in PPP5C associated with microcephaly, seizures, and developmental delay. Mol Genet Metab 2022; 136:65-73. [PMID: 35361529 DOI: 10.1016/j.ymgme.2022.03.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 03/13/2022] [Indexed: 11/27/2022]
Abstract
We describe a proband evaluated through the Undiagnosed Diseases Network (UDN) who presented with microcephaly, developmental delay, and refractory epilepsy with a de novo p.Ala47Thr missense variant in the protein phosphatase gene, PPP5C. This gene has not previously been associated with a Mendelian disease, and based on the population database, gnomAD, the gene has a low tolerance for loss-of-function variants (pLI = 1, o/e = 0.07). We functionally evaluated the PPP5C variant in C. elegans by knocking the variant into the orthologous gene, pph-5, at the corresponding residue, Ala48Thr. We employed assays in three different biological processes where pph-5 was known to function through opposing the activity of genes, mec-15 and sep-1. We demonstrated that, in contrast to control animals, the pph-5 Ala48Thr variant suppresses the neurite growth phenotype and the GABA signaling defects of mec-15 mutants, and the embryonic lethality of sep-1 mutants. The Ala48Thr variant did not display dominance and behaved similarly to the reference pph-5 null, indicating that the variant is likely a strong hypomorph or complete loss-of-function. We conclude that pph-5 Ala48Thr is damaging in C. elegans. By extension in the proband, PPP5C p.Ala47Thr is likely damaging, the de novo dominant presentation is consistent with haplo-insufficiency, and the PPP5C variant is likely responsible for one or more of the proband's phenotypes.
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Affiliation(s)
- Sara M Fielder
- Department of Pediatrics, Washington University in St Louis School of Medicine, St Louis, MO 63110, USA
| | - Jill A Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Lindsay C Burrage
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA
| | - Lisa Emrick
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA
| | - Seema Lalani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA
| | - Ruben Attali
- Genomic Research Department, Emedgene Technologies, 6744332 Tel Aviv, Israel
| | - Joshua N Bembenek
- Department of Obstetrics and Gynecology, C.S. Mott Center for Human Growth and Development, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Hieu Hoang
- Department of Pediatrics, Washington University in St Louis School of Medicine, St Louis, MO 63110, USA
| | - Dustin Baldridge
- Department of Pediatrics, Washington University in St Louis School of Medicine, St Louis, MO 63110, USA
| | - Gary A Silverman
- Department of Pediatrics, Washington University in St Louis School of Medicine, St Louis, MO 63110, USA
| | - Tim Schedl
- Department of Genetics, Washington University in St Louis School of Medicine, St Louis, MO 63110, USA
| | - Stephen C Pak
- Department of Pediatrics, Washington University in St Louis School of Medicine, St Louis, MO 63110, USA.
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HIF-1 Interacts with TRIM28 and DNA-PK to release paused RNA polymerase II and activate target gene transcription in response to hypoxia. Nat Commun 2022; 13:316. [PMID: 35031618 PMCID: PMC8760265 DOI: 10.1038/s41467-021-27944-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 12/15/2021] [Indexed: 12/11/2022] Open
Abstract
Hypoxia-inducible factor-1 (HIF-1) is a transcription factor that acts as a regulator of oxygen (O2) homeostasis in metazoan species by binding to hypoxia response elements (HREs) and activating the transcription of hundreds of genes in response to reduced O2 availability. RNA polymerase II (Pol II) initiates transcription of many HIF target genes under non-hypoxic conditions but pauses after approximately 30–60 nucleotides and requires HIF-1 binding for release. Here we report that in hypoxic breast cancer cells, HIF-1 recruits TRIM28 and DNA-dependent protein kinase (DNA-PK) to HREs to release paused Pol II. We show that HIF-1α and TRIM28 assemble the catalytically-active DNA-PK heterotrimer, which phosphorylates TRIM28 at serine-824, enabling recruitment of CDK9, which phosphorylates serine-2 of the Pol II large subunit C-terminal domain as well as the negative elongation factor to release paused Pol II, thereby stimulating productive transcriptional elongation. Our studies reveal a molecular mechanism by which HIF-1 stimulates gene transcription and reveal that the anticancer effects of drugs targeting DNA-PK in breast cancer may be due in part to their inhibition of HIF-dependent transcription. Hypoxia-inducible factor-1 (HIF-1) is a transcription factor that modulates target gene expression in response to changes in oxygen availability. Here the authors show that HIF-1 forms a complex with TRIM28 and DNA-dependent protein kinase (DNA-PK) that phosphorylates TRIM28. This leads to CDK9 recruitment, which stimulates RNA polymerase II (RNAPII) pause release and transcriptional elongation.
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Lee J, Choi S, Jung D, Jung Y, Kim JH, Jung S, Lee WS. Mutational Characterization of Colorectal Cancer from Korean Patients with Targeted Sequencing. J Cancer 2022; 12:7300-7310. [PMID: 35003350 PMCID: PMC8734410 DOI: 10.7150/jca.61324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 10/09/2021] [Indexed: 11/11/2022] Open
Abstract
Purpose: Effective treatment of colorectal cancer could benefit from understanding molecular characteristics including mutation profiles of important genes. This study aimed to explore the molecular characteristics of colorectal cancer based on next generation sequencing. Methods: The mutational characteristics by targeted next generation sequencing in 172 colorectal tumor samples from Korean patients were evaluated to explore their associations with clinical features. Targeted sequencing of 375 genes was performed with an average target-depth of 800X. Results: TP53 and APC showed higher mutation frequencies from the left-sided tumors, while CTNNB1 were more frequent from the right-sided tumors. The tumor suppressor NOTCH1 and the DNA strand break repair gene PALB2 were more frequently mutated in early onset tumors. KRAS and PTEN mutations were more frequent from patients with advanced cancers by cancer antigen markers. TP53 and BRAF mutations were more frequent from patients of T3 and T4 stages, where their variant allele fractions were generally higher in T4 tumors, implying that advanced tumors have higher fraction of cancer cells with TP53 and BRAF mutations. Mutational profiles of these patients were also assessed with other clinical features. Comparison of mutational characteristics with the Caucasian subjects from independent data showed that the identified mutational characteristics are largely Korean-specific except for a few key colorectal cancer genes. Conclusion: Next generation sequencing-based targeted sequencing can provide valuable information on molecular characterization of colorectal cancer patients, and its clinically relevant information can provide benefits to better understand colorectal cancer.
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Affiliation(s)
- Jongmin Lee
- Gachon Institute of Genome Medicine and Science, Gachon University Gil Medical Center, Incheon, Republic of Korea.,Gachon Advanced Institute for Health Science and Technology, Gachon University, Incheon, Republic of Korea
| | - Sangtae Choi
- Department of Surgery, Gachon University College of Medicine Gil Medical Center, Incheon, Republic of Korea
| | - Donghae Jung
- Department of Pathology, Gachon University College of Medicine Gil Medical Center, Incheon, Republic of Korea
| | - YunJae Jung
- Gachon Advanced Institute for Health Science and Technology, Gachon University, Incheon, Republic of Korea.,Department of Microbiology, Gachon University College of Medicine, Incheon, Republic of Korea
| | - Jung Ho Kim
- Department of Internal Medicine, Gachon University College of Medicine Gil Medical Center, Incheon, Republic of Korea
| | - Sungwon Jung
- Gachon Institute of Genome Medicine and Science, Gachon University Gil Medical Center, Incheon, Republic of Korea.,Gachon Advanced Institute for Health Science and Technology, Gachon University, Incheon, Republic of Korea.,Department of Genome Medicine and Science, Gachon University College of Medicine, Incheon, Republic of Korea
| | - Won-Suk Lee
- Department of Surgery, Gachon University College of Medicine Gil Medical Center, Incheon, Republic of Korea
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11
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Molinaro C, Martoriati A, Cailliau K. Proteins from the DNA Damage Response: Regulation, Dysfunction, and Anticancer Strategies. Cancers (Basel) 2021; 13:3819. [PMID: 34359720 PMCID: PMC8345162 DOI: 10.3390/cancers13153819] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/22/2021] [Accepted: 07/26/2021] [Indexed: 12/21/2022] Open
Abstract
Cells respond to genotoxic stress through a series of complex protein pathways called DNA damage response (DDR). These monitoring mechanisms ensure the maintenance and the transfer of a correct genome to daughter cells through a selection of DNA repair, cell cycle regulation, and programmed cell death processes. Canonical or non-canonical DDRs are highly organized and controlled to play crucial roles in genome stability and diversity. When altered or mutated, the proteins in these complex networks lead to many diseases that share common features, and to tumor formation. In recent years, technological advances have made it possible to benefit from the principles and mechanisms of DDR to target and eliminate cancer cells. These new types of treatments are adapted to the different types of tumor sensitivity and could benefit from a combination of therapies to ensure maximal efficiency.
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Affiliation(s)
| | | | - Katia Cailliau
- Univ. Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France; (C.M.); (A.M.)
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12
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Neumann J, Boknik P, Kirchhefer U, Gergs U. The role of PP5 and PP2C in cardiac health and disease. Cell Signal 2021; 85:110035. [PMID: 33964402 DOI: 10.1016/j.cellsig.2021.110035] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/16/2021] [Accepted: 05/03/2021] [Indexed: 02/08/2023]
Abstract
Protein phosphatases are important, for example, as functional antagonists of β-adrenergic stimulation of the mammalian heart. While β-adrenergic stimulations increase the phosphorylation state of regulatory proteins and therefore force of contraction in the heart, these phosphorylations are reversed and thus force is reduced by the activity of protein phosphatases. In this context the role of PP5 and PP2C is starting to unravel. They do not belong to the same family of phosphatases with regard to sequence homology, many similarities with regard to location, activation by lipids and putative substrates have been worked out over the years. We also suggest which pathways for regulation of PP5 and/or PP2C described in other tissues and not yet in the heart might be useful to look for in cardiac tissue. Both phosphatases might play a role in signal transduction of sarcolemmal receptors in the heart. Expression of PP5 and PP2C can be increased by extracellular stimuli in the heart. Because PP5 is overexpressed in failing animal and human hearts, and because overexpression of PP5 or PP2C leads to cardiac hypertrophy and KO of PP5 leads to cardiac hypotrophy, one might argue for a role of PP5 and PP2C in heart failure. Because PP5 and PP2C can reduce, at least in vitro, the phosphorylation state of proteins thought to be relevant for cardiac arrhythmias, a role of these phosphatases for cardiac arrhythmias is also probable. Thus, PP5 and PP2C might be druggable targets to treat important cardiac diseases like heart failure, cardiac hypertrophy and cardiac arrhythmias.
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Affiliation(s)
- Joachim Neumann
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, Magdeburger Str. 4, D-06097 Halle, Germany.
| | - Peter Boknik
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Westfälische Wilhelms-Universität, Domagkstraße 12, D-48149 Münster, Germany.
| | - Uwe Kirchhefer
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Westfälische Wilhelms-Universität, Domagkstraße 12, D-48149 Münster, Germany.
| | - Ulrich Gergs
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, Magdeburger Str. 4, D-06097 Halle, Germany.
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13
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Song B, Liu D, Greco TM, Cristea IM. Post-translational modification control of viral DNA sensors and innate immune signaling. Adv Virus Res 2021; 109:163-199. [PMID: 33934827 PMCID: PMC8489191 DOI: 10.1016/bs.aivir.2021.03.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The vertebrate innate immune system confers host cells with mechanisms to protect against both evolutionarily ancient pathogens and newly emerging pathogenic strains. Innate immunity relies on the host cell's ability to distinguish between self and pathogen-derived molecules. To achieve this, the innate immune system uses germline encoded receptors called pattern recognition receptors (PRRs), which recognize various molecular signatures, including nucleic acids, proteins, lipids, glycans and glycolipids. Among these molecules, the recognition of pathogenic, mislocalized, or damaged DNA by cellular protein receptors, commonly called DNA sensors, represents a major surveillance pathway for initiating immune signaling. The ability of cells to temporally regulate DNA sensor activation and subsequent signal termination is critical for effective immune signaling. These same mechanisms are also co-opted by pathogens to promote their replication. Therefore, there is significant interest in understanding DNA sensor regulatory networks during microbial infections and autoimmune disease. One emerging aspect of DNA sensor regulation is through post-translational modifications (PTMs), including phosphorylation, acetylation, ubiquitination, ADP-ribosylation, SUMOylation, methylation, deamidation, glutamylation. In this chapter, we discuss how PTMs have been shown to positively or negatively impact DNA sensor functions via diverse mechanisms, including direct regulation of enzymatic activity, protein-protein and protein-DNA interactions, protein translocations and protein turnover. In addition, we highlight the ability of virus-induced PTMs to promote immune evasion. We also discuss the recent evidence linking PTMs on DNA sensors with human diseases and more broadly, highlight promising directions for future research on PTM-mediated regulation of DNA sensor-dependent immune signaling.
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Affiliation(s)
- Bokai Song
- Department of Molecular Biology, Princeton University, Princeton, NJ, United States
| | - Dawei Liu
- Department of Molecular Biology, Princeton University, Princeton, NJ, United States
| | - Todd M Greco
- Department of Molecular Biology, Princeton University, Princeton, NJ, United States
| | - Ileana M Cristea
- Department of Molecular Biology, Princeton University, Princeton, NJ, United States.
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14
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Yepes S, Tucker MA, Koka H, Xiao Y, Jones K, Vogt A, Burdette L, Luo W, Zhu B, Hutchinson A, Yeager M, Hicks B, Freedman ND, Chanock SJ, Goldstein AM, Yang XR. Using whole-exome sequencing and protein interaction networks to prioritize candidate genes for germline cutaneous melanoma susceptibility. Sci Rep 2020; 10:17198. [PMID: 33057211 PMCID: PMC7560829 DOI: 10.1038/s41598-020-74293-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 09/24/2020] [Indexed: 02/07/2023] Open
Abstract
Although next-generation sequencing has demonstrated great potential for novel gene discovery, confirming disease-causing genes after initial discovery remains challenging. Here, we applied a network analysis approach to prioritize candidate genes identified from whole-exome sequencing analysis of 98 cutaneous melanoma patients from 27 families. Using a network propagation method, we ranked candidate genes by their similarity to known disease genes in protein-protein interaction networks and identified gene clusters with functional connectivity. Using this approach, we identified several new candidate susceptibility genes that warrant future investigations such as NGLY1, IL1RN, FABP2, PRKDC, and PROSER2. The propagated network analysis also allowed us to link families that did not have common underlying genes but that carried variants in genes that interact on protein-protein interaction networks. In conclusion, our study provided an analysis perspective for gene prioritization in the context of genetic heterogeneity across families and prioritized top potential candidate susceptibility genes in our dataset.
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Affiliation(s)
- Sally Yepes
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Margaret A Tucker
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Hela Koka
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Yanzi Xiao
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Kristine Jones
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
- Cancer Genomics Research Laboratory, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Aurelie Vogt
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
- Cancer Genomics Research Laboratory, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Laurie Burdette
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
- Cancer Genomics Research Laboratory, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Wen Luo
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
- Cancer Genomics Research Laboratory, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Bin Zhu
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
- Cancer Genomics Research Laboratory, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Amy Hutchinson
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
- Cancer Genomics Research Laboratory, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Meredith Yeager
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
- Cancer Genomics Research Laboratory, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Belynda Hicks
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
- Cancer Genomics Research Laboratory, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Neal D Freedman
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Stephen J Chanock
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Alisa M Goldstein
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Xiaohong R Yang
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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15
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Sager RA, Dushukyan N, Woodford M, Mollapour M. Structure and function of the co-chaperone protein phosphatase 5 in cancer. Cell Stress Chaperones 2020; 25:383-394. [PMID: 32239474 PMCID: PMC7193036 DOI: 10.1007/s12192-020-01091-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 03/04/2020] [Accepted: 03/12/2020] [Indexed: 12/12/2022] Open
Abstract
Protein phosphatase 5 (PP5) is a serine/threonine protein phosphatase that regulates many cellular functions including steroid hormone signaling, stress response, proliferation, apoptosis, and DNA repair. PP5 is also a co-chaperone of the heat shock protein 90 molecular chaperone machinery that assists in regulation of cellular signaling pathways essential for cell survival and growth. PP5 plays a significant role in survival and propagation of multiple cancers, which makes it a promising target for cancer therapy. Though there are several naturally occurring PP5 inhibitors, none is specific for PP5. Here, we review the roles of PP5 in cancer progression and survival and discuss the unique features of the PP5 structure that differentiate it from other phosphoprotein phosphatase (PPP) family members and make it an attractive therapeutic target.
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Affiliation(s)
- Rebecca A Sager
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
- Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
- College of Medicine, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Natela Dushukyan
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
- Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Mark Woodford
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
- Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Mehdi Mollapour
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA.
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, 13210, USA.
- Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY, 13210, USA.
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16
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Cell Cycle and DNA Repair Regulation in the Damage Response: Protein Phosphatases Take Over the Reins. Int J Mol Sci 2020; 21:ijms21020446. [PMID: 31936707 PMCID: PMC7014277 DOI: 10.3390/ijms21020446] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 12/29/2019] [Accepted: 01/02/2020] [Indexed: 12/14/2022] Open
Abstract
Cells are constantly suffering genotoxic stresses that affect the integrity of our genetic material. Genotoxic insults must be repaired to avoid the loss or inappropriate transmission of the genetic information, a situation that could lead to the appearance of developmental abnormalities and tumorigenesis. To combat this threat, eukaryotic cells have evolved a set of sophisticated molecular mechanisms that are collectively known as the DNA damage response (DDR). This surveillance system controls several aspects of the cellular response, including the detection of lesions, a temporary cell cycle arrest, and the repair of the broken DNA. While the regulation of the DDR by numerous kinases has been well documented over the last decade, the complex roles of protein dephosphorylation have only recently begun to be investigated. Here, we review recent progress in the characterization of DDR-related protein phosphatases during the response to a DNA lesion, focusing mainly on their ability to modulate the DNA damage checkpoint and the repair of the damaged DNA. We also discuss their protein composition and structure, target specificity, and biochemical regulation along the different stages encompassed in the DDR. The compilation of this information will allow us to better comprehend the physiological significance of protein dephosphorylation in the maintenance of genome integrity and cell viability in response to genotoxic stress.
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17
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Dziegielewski J, Bońkowska MA, Poniecka EA, Heo J, Du K, Crittenden RB, Bender TP, Brautigan DL, Larner JM. Deletion of the SAPS1 subunit of protein phosphatase 6 in mice increases radiosensitivity and impairs the cellular DNA damage response. DNA Repair (Amst) 2019; 85:102737. [PMID: 31751917 DOI: 10.1016/j.dnarep.2019.102737] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 09/17/2019] [Accepted: 10/15/2019] [Indexed: 12/24/2022]
Abstract
Cellular responses to DNA damage include activation of DNA-dependent protein kinase (DNA-PK) through, among others, the serine/threonine protein phosphatase 6 (PP6). We previously showed that recognition of DNA-PKcs is mediated by the SAPS1 PP6 regulatory subunit. Here, we report and characterize a SAPS1 null mouse and investigate the effects of deletion on DNA damage signaling and repair. Strikingly, neither SAPS1-null animals nor cells derived from them show gross defects, unless subjected to DNA damage by radiation or chemical agents. The overall survival of SAPS1-null animals following whole body irradiation is significantly shortened as compared to wild-type mice, and the clonogenic survival of null cells subjected to ionizing radiation is reduced. The dephosphorylation of DNA damage/repair markers, such as γH2AX, p53 and Kap1, is diminished in SAPS1-null cells as compared to wild-type controls. Our results demonstrate that loss of SAPS1 confers sensitivity to DNA damage and confirms previously reported cellular phenotypes of SAPS1 knock-down in human glioma cells. The results support a role for PP6 regulatory subunit SAPS1 in DNA damage responses, and offer a novel target for sensitization to enhance current tumor therapies, with a potential for limited deleterious side effects.
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Affiliation(s)
- Jaroslaw Dziegielewski
- Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Magdalena A Bońkowska
- Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Ewa A Poniecka
- Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Jinho Heo
- Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Kangping Du
- Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Rowena B Crittenden
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Beirne B. Carter Center for Immunology Research, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Timothy P Bender
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Beirne B. Carter Center for Immunology Research, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - David L Brautigan
- Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - James M Larner
- Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
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18
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Wang J, Shen T, Zhu W, Dou L, Gu H, Zhang L, Yang Z, Chen H, Zhou Q, Sánchez ER, Field LJ, Mayo LD, Xie Z, Xiao D, Lin X, Shou W, Yong W. Protein phosphatase 5 and the tumor suppressor p53 down-regulate each other's activities in mice. J Biol Chem 2018; 293:18218-18229. [PMID: 30262665 DOI: 10.1074/jbc.ra118.004256] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 09/17/2018] [Indexed: 12/20/2022] Open
Abstract
Protein phosphatase 5 (PP5), a serine/threonine phosphatase, has a wide range of biological functions and exhibits elevated expression in tumor cells. We previously reported that pp5-deficient mice have altered ataxia-telangiectasia mutated (ATM)-mediated signaling and function. However, this regulation was likely indirect, as ATM is not a known PP5 substrate. In the current study, we found that pp5-deficient mice are hypersensitive to genotoxic stress. This hypersensitivity was associated with the marked up-regulation of the tumor suppressor tumor protein p53 and its downstream targets cyclin-dependent kinase inhibitor 1A (p21), MDM2 proto-oncogene (MDM2), and phosphatase and tensin homolog (PTEN) in pp5-deficient tissues and cells. These observations suggested that PP5 plays a role in regulating p53 stability and function. Experiments conducted with p53 +/- pp5 +/- or p53 +/- pp5 -/- mice revealed that complete loss of PP5 reduces tumorigenesis in the p53 +/- mice. Biochemical analyses further revealed that PP5 directly interacts with and dephosphorylates p53 at multiple serine/threonine residues, resulting in inhibition of p53-mediated transcriptional activity. Interestingly, PP5 expression was significantly up-regulated in p53-deficient cells, and further analysis of pp5 promoter activity revealed that p53 strongly represses PP5 transcription. Our results suggest a reciprocal regulatory interplay between PP5 and p53, providing an important feedback mechanism for the cellular response to genotoxic stress.
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Affiliation(s)
- Jun Wang
- From the Comparative Medical Center, Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences, Beijing 100021, China,; School of Life Sciences, Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Tao Shen
- DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas 77030
| | - Wuqiang Zhu
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Longyu Dou
- From the Comparative Medical Center, Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences, Beijing 100021, China
| | - Hao Gu
- From the Comparative Medical Center, Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences, Beijing 100021, China
| | - Lingling Zhang
- From the Comparative Medical Center, Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences, Beijing 100021, China
| | - Zhenyun Yang
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Hanying Chen
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Qi Zhou
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Edwin R Sánchez
- Department of Physiology and Pharmacology, College of Medicine, University of Toledo, Toledo, Ohio 43614, and
| | - Loren J Field
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Lindsey D Mayo
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Zhongwen Xie
- School of Life Sciences, Anhui Agricultural University, Hefei, Anhui 230036, China
| | - Deyong Xiao
- Fountain Valley Institute of Life Sciences and Fountain Valley Biomedical Technology Company, Dalian Hi-Tech Industrial Zone, Dalian 116023, China
| | - Xia Lin
- DeBakey Department of Surgery, Baylor College of Medicine, Houston, Texas 77030
| | - Weinian Shou
- Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana 46202,.
| | - Weidong Yong
- From the Comparative Medical Center, Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences, Beijing 100021, China,; Herman B. Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana 46202,.
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19
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Lv JM, Chen L, Gao Y, Huang H, Pan XW, Liu X, Chen M, Qu FJ, Li L, Wang JK, Cui XG, Xu DF. PPP5C promotes cell proliferation and survival in human prostate cancer by regulating of the JNK and ERK1/2 phosphorylation. Onco Targets Ther 2018; 11:5797-5809. [PMID: 30254472 PMCID: PMC6140725 DOI: 10.2147/ott.s161280] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Background Prostate cancer (PCa) is one of the most common malignancies and a major leading cause of cancer-related deaths in males. And it is necessary to explore new molecular targets to enhance diagnosis and treatment level of the PCa. Serine/threonine protein phosphatase 5 (PPP5C) is a vital molecule that Involve in complex cell physiological activity. Purpose The objective of this study was to detecte the expression level of PPP5C in the tissue of prostate cancer patients and further discussed the PPP5C biological function and mechanisms on the PCa. Methods The expression level of PPP5C was analyzed by immunohistochemistry and ONCOM-INE datasets. Lentivirus-mediated short hairpin RNA (shRNA) was constructed to silence the expression of PPP5C in prostate cancer cell. Cell viability and proliferation were measured using MTT and colony formation, and the cell cycle and apoptosis was analyszed by flow cytometry. The changes of downstream protein level and protein phosphorylation level were detected by western blot. Results PPP5C was highly expressed in PCa tissue as analyzed by immunohistochemistry and ONCOMINE datasets. PPP5C Knockdown inhibited cell proliferation and colony formation in PCa cells. Flow cytometry analysis showed that DU145, PC3 and 22RV1 PCa cells deprived of PPP5C were arrested in G0/G1 phase and became apoptotic. Western blot analysis indicated that PPP5C knockdown could promote JNK and ERK phosphorylation. Conclusion Our study indicated that the PPP5C may become a new potential diagnostic biomarker and therapeutic target for the PCa.
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Affiliation(s)
- Jian-Min Lv
- Department of Urinary Surgery, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China, .,Department of Urinary Surgery, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China.,Department of Urinary Surgery, Third Affiliated Hospital, Second Military Medical University, Shanghai 201805, China,
| | - Lu Chen
- Department of Urinary Surgery, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China,
| | - Yi Gao
- Department of Urinary Surgery, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China,
| | - Hai Huang
- Department of Urinary Surgery, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China, .,Department of Urinary Surgery, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China.,Department of Urinary Surgery, Third Affiliated Hospital, Second Military Medical University, Shanghai 201805, China,
| | - Xiu-Wu Pan
- Department of Urinary Surgery, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China.,Department of Urinary Surgery, Third Affiliated Hospital, Second Military Medical University, Shanghai 201805, China,
| | - Xi Liu
- Department of Urinary Surgery, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China,
| | - Ming Chen
- Department of Urinary Surgery, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China
| | - Fa-Jun Qu
- Department of Urinary Surgery, Third Affiliated Hospital, Second Military Medical University, Shanghai 201805, China,
| | - Lin Li
- Department of Urinary Surgery, Third Affiliated Hospital, Second Military Medical University, Shanghai 201805, China,
| | - Jun-Kai Wang
- Department of Urinary Surgery, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China
| | - Xin-Gang Cui
- Department of Urinary Surgery, Third Affiliated Hospital, Second Military Medical University, Shanghai 201805, China, .,Department of Urinary Surgery, Gongli Hospital, Second Military Medical University, Shanghai 200135, China,
| | - Dan-Feng Xu
- Department of Urinary Surgery, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China,
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20
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Huang CY, Hsieh FS, Wang CY, Chen LJ, Chang SS, Tsai MH, Hung MH, Kuo CW, Shih CT, Chao TI, Chen KF. Palbociclib enhances radiosensitivity of hepatocellular carcinoma and cholangiocarcinoma via inhibiting ataxia telangiectasia-mutated kinase-mediated DNA damage response. Eur J Cancer 2018; 102:10-22. [PMID: 30103095 DOI: 10.1016/j.ejca.2018.07.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 07/12/2018] [Accepted: 07/13/2018] [Indexed: 12/15/2022]
Abstract
AIM Palbociclib is an oral cyclin-dependent kinase 4/6 inhibitor, which is efficacious in treating breast cancer. Currently, there are numerous active clinical trials testing palbociclib alone or in combination with other medications for treating various types of malignancies. Here, we evaluated the anti-cancer effect of palbociclib in combination with radiation therapy (RT) for treating human hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) and addressed the molecular mechanism behind the combination therapy. METHODS Immunofluorescence staining of γH2AX or 53BP1 was used to determine the effect of palbociclib on double-strand break (DSB) repair. Clonogenic assays, sphere formation and cell death ELISA were performed to study the sensitising effect of palbociclib on radiation-induced cytotoxicity. Signal alteration in DSB repair pathways was examined by Western blot analysis. Finally, we evaluated the in vivo anti-cancer activity and the associated molecular events of the combination therapy in a preclinical HCC xenograft model. RESULTS Palbociclib affected the kinetics of DNA repair and enhanced the radiation sensitivity of HCC and CCA cells. Importantly, we found that palbociclib inhibits ataxia telangiectasia-mutated (ATM) kinase, the key upstream kinase responding to RT-induced DSBs. Furthermore, we showed that the inhibitory effect of palbociclib on RT-induced ATM kinase activation is mediated by protein phosphatase 5 (PP5). Both in vitro and in vivo investigations revealed that the inhibition of the PP5-ATM axis by palbociclib after DNA damage is responsible for the synergism between palbociclib and RT. CONCLUSION Our findings provide a novel combination strategy against liver cancer cells. Clinical trials using palbociclib as an adjuvant in RT are warranted.
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Affiliation(s)
- Chao-Yuan Huang
- Division of Radiation Oncology, Department of Oncology, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan; Department of Medical Imaging and Radiological Technology, Yuanpei University, Hsinchu, Taiwan
| | - Feng-Shu Hsieh
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan.
| | - Cheng-Yi Wang
- Department of Internal Medicine, Cardinal Tien Hospital, Fu Jen Catholic University, New Taipei City, Taiwan
| | - Li-Ju Chen
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
| | - Shih-Shin Chang
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
| | - Ming-Hsien Tsai
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
| | - Man-Hsin Hung
- Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, Taipei, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Chiung-Wen Kuo
- Department of Medical Imaging and Radiological Technology, Yuanpei University, Hsinchu, Taiwan
| | - Chi-Ting Shih
- Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei, Taiwan
| | | | - Kuen-Feng Chen
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan; National Center of Excellence for Clinical Trial and Research, National Taiwan University Hospital, Taipei, Taiwan.
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21
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The Human T-Cell Leukemia Virus Type 1 Basic Leucine Zipper Factor Attenuates Repair of Double-Stranded DNA Breaks via Nonhomologous End Joining. J Virol 2018; 92:JVI.00672-18. [PMID: 29769340 DOI: 10.1128/jvi.00672-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 05/10/2018] [Indexed: 12/27/2022] Open
Abstract
Adult T-cell leukemia (ATL) is a fatal malignancy of CD4+ T cells infected with human T-cell leukemia virus type 1 (HTLV-1). ATL cells often exhibit random gross chromosomal rearrangements that are associated with the induction and improper repair of double-stranded DNA breaks (DSBs). The viral oncoprotein Tax has been reported to impair DSB repair but has not been shown to be consistently expressed throughout all phases of infection. The viral oncoprotein HTLV-1 basic leucine zipper (bZIP) factor (HBZ) is consistently expressed prior to and throughout disease progression, but it is unclear whether it also influences DSB repair. We report that HBZ attenuates DSB repair by nonhomologous end joining (NHEJ), in a manner dependent upon the bZIP domain. HBZ was found to interact with two vital members of the NHEJ core machinery, Ku70 and Ku80, and to be recruited to DSBs in a bZIP-dependent manner in vitro We observed that HBZ expression also resulted in a bZIP-dependent delay in DNA protein kinase (DNA-PK) activation following treatment with etoposide. Although Tax is reported to interact with Ku70, we did not find Tax expression to interfere with HBZ:Ku complex formation. However, as Tax was reported to saturate NHEJ, we found that this effect masked the attenuation of NHEJ by HBZ. Overall, these data suggest that DSB repair mechanisms are impaired not only by Tax but also by HBZ and show that HBZ expression may significantly contribute to the accumulation of chromosomal abnormalities during HTLV-1-mediated oncogenesis.IMPORTANCE Human T-cell leukemia virus type 1 (HTLV-1) infects 15 million to 20 million people worldwide. Approximately 90% of infected individuals are asymptomatic and may remain undiagnosed, increasing the risk that they will unknowingly transmit the virus. About 5% of the HTLV-1-positive population develop adult T-cell leukemia (ATL), a fatal disease that is not highly responsive to treatment. Although ATL development remains poorly understood, two viral proteins, Tax and HBZ, have been implicated in driving disease progression by manipulating host cell signaling and transcriptional pathways. Unlike Tax, HBZ expression is consistently observed in all infected individuals, making it important to elucidate the specific role of HBZ in disease progression. Here, we present evidence that HBZ could promote the accumulation of double-stranded DNA breaks (DSBs) through the attenuation of the nonhomologous end joining (NHEJ) repair pathway. This effect may lead to genome instability, ultimately contributing to the development of ATL.
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22
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Zhu S, Fisher LA, Bessho T, Peng A. Protein phosphatase 1 and phosphatase 1 nuclear targeting subunit-dependent regulation of DNA-dependent protein kinase and non-homologous end joining. Nucleic Acids Res 2017; 45:10583-10594. [PMID: 28985363 PMCID: PMC5737533 DOI: 10.1093/nar/gkx686] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Accepted: 07/28/2017] [Indexed: 12/29/2022] Open
Abstract
DNA-dependent protein kinase catalytic subunit (DNA-PKcs) plays a key role in mediating non-homologous end joining (NHEJ), a major repair pathway for DNA double-strand breaks (DSBs). The activation, function and dynamics of DNA-PKcs is regulated largely by its reversible phosphorylation at numerous residues, many of which are targeted by DNA-PKcs itself. Interestingly, these DNA-PKcs phosphorylation sites function in a distinct, and sometimes opposing manner, suggesting that they are differentially regulated via complex actions of both kinases and phosphatases. In this study we identified several phosphatase subunits as potential DSB-associated proteins. In particular, protein phosphatase 1 (PP1) is recruited to a DSB-mimicking substrate in Xenopus egg extracts and sites of laser microirradiation in human cells. Depletion of PP1 impairs NHEJ in both Xenopus egg extracts and human cells. PP1 binds multiple motifs of DNA-PKcs, regulates DNA-PKcs phosphorylation, and is required for DNA-PKcs activation after DNA damage. Interestingly, phosphatase 1 nuclear targeting subunit (PNUTS), an inhibitory regulator of PP1, is also recruited to DNA damage sites to promote NHEJ. PNUTS associates with the DNA-PK complex and is required for DNA-PKcs phosphorylation at Ser-2056 and Thr-2609. Thus, PNUTS and PP1 together fine-tune the dynamic phosphorylation of DNA-PKcs after DNA damage to mediate NHEJ.
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Affiliation(s)
- Songli Zhu
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE 68583, USA
| | - Laura A Fisher
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE 68583, USA
| | - Tadayoshi Bessho
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Aimin Peng
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE 68583, USA
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23
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Abramenkovs A, Stenerlöw B. Measurement of DNA-Dependent Protein Kinase Phosphorylation Using Flow Cytometry Provides a Reliable Estimate of DNA Repair Capacity. Radiat Res 2017; 188:597-604. [PMID: 28952912 DOI: 10.1667/rr14693.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Uncontrolled generation of DNA double-strand breaks (DSBs) in cells is regarded as a highly toxic event that threatens cell survival. Radiation-induced DNA DSBs are commonly measured by pulsed-field gel electrophoresis, microscopic evaluation of accumulating DNA damage response proteins (e.g., 53BP1 or γ-H2AX) or flow cytometric analysis of γ-H2AX. The advantage of flow cytometric analysis is that DSB formation and repair can be studied in relationship to cell cycle phase or expression of other proteins. However, γ-H2AX is not able to monitor repair kinetics within the first 60 min postirradiation, a period when most DSBs undergo repair. A key protein in non-homologous end joining repair is the catalytic subunit of DNA-dependent protein kinase. Among several phosphorylation sites of DNA-dependent protein kinase, the threonine at position 2609 (T2609), which is phosphorylated by ataxia telangiectasia mutated (ATM) or DNA-dependent protein kinase catalytic subunit itself, activates the end processing of DSB. Using flow cytometry, we show here that phosphorylation at T2609 is faster in response to DSBs than γ-H2AX. Furthermore, flow cytometric analysis of T2609 resulted in a better representation of fast repair kinetics than analysis of γ-H2AX. In cells with reduced ligase IV activity, and wild-type cells where DNA-dependent protein kinase activity was inhibited, the reduced DSB repair capacity was observed by T2609 evaluation using flow cytometry. In conclusion, flow cytometric evaluation of DNA-dependent protein kinase T2609 can be used as a marker for early DSB repair and gives a better representation of early repair events than analysis of γ-H2AX.
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Affiliation(s)
- Andris Abramenkovs
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala, Sweden
| | - Bo Stenerlöw
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala, Sweden
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24
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Penndorf D, Tadić V, Witte OW, Grosskreutz J, Kretz A. DNA strand breaks and TDP-43 mislocation are absent in the murine hSOD1G93A model of amyotrophic lateral sclerosis in vivo and in vitro. PLoS One 2017; 12:e0183684. [PMID: 28832631 PMCID: PMC5568271 DOI: 10.1371/journal.pone.0183684] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 08/09/2017] [Indexed: 12/12/2022] Open
Abstract
Mutations in the human Cu/Zn superoxide dismutase type-1 (hSOD1) gene are common in familial amyotrophic lateral sclerosis (fALS). The pathophysiology has been linked to, e.g., organelle dysfunction, RNA metabolism and oxidative DNA damage conferred by SOD1 malfunction. However, apart from metabolically evoked DNA oxidation, it is unclear whether severe genotoxicity including DNA single-strand breaks (SSBs) and double-strand breaks (DSBs), originates from loss of function of nuclear SOD1 enzyme. Factors that endogenously interfere with DNA integrity and repair complexes in hSOD1-mediated fALS remain similarly unexplored. In this regard, uncontrolled activation of transposable elements (TEs) might contribute to DNA disintegration and neurodegeneration. The aim of this study was to elucidate the role of the fALS-causing hSOD1G93A mutation in the generation of severe DNA damage beyond well-characterized DNA base oxidation. Therefore, DNA damage was assessed in spinal tissue of hSOD1G93A-overexpressing mice and in corresponding motor neuron-enriched cell cultures in vitro. Overexpression of the hSOD1G93A locus did not change the threshold for severe DNA damage per se. We found that levels of SSBs and DSBs were unaltered between hSOD1G93A and control conditions, as demonstrated in post-mitotic motor neurons and in astrocytes susceptible to replication-dependent DNA breakage. Analogously, parameters indicative of DNA damage response processes were not activated in vivo or in vitro. Evidence for a mutation-related elevation in TE activation was not detected, in accordance with the absence of TAR DNA binding protein 43 (TDP-43) proteinopathy in terms of cytoplasmic mislocation or nuclear loss, as nuclear TDP-43 is supposed to silence TEs physiologically. Conclusively, the superoxide dismutase function of SOD1 might not be required to preserve DNA integrity in motor neurons, at least when the function of TDP-43 is unaltered. Our data establish a foundation for further investigations addressing functional TDP-43 interaction with ALS-relevant genetic mutations.
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Affiliation(s)
- Diane Penndorf
- Hans Berger Department of Neurology, Jena University Hospital, Jena, Thuringia, Germany
| | - Vedrana Tadić
- Hans Berger Department of Neurology, Jena University Hospital, Jena, Thuringia, Germany
| | - Otto W. Witte
- Hans Berger Department of Neurology, Jena University Hospital, Jena, Thuringia, Germany
| | - Julian Grosskreutz
- Hans Berger Department of Neurology, Jena University Hospital, Jena, Thuringia, Germany
| | - Alexandra Kretz
- Hans Berger Department of Neurology, Jena University Hospital, Jena, Thuringia, Germany
- * E-mail:
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25
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Ashton NW, Paquet N, Shirran SL, Bolderson E, Kariawasam R, Touma C, Fallahbaghery A, Gamsjaeger R, Cubeddu L, Botting C, Pollock PM, O'Byrne KJ, Richard DJ. hSSB1 phosphorylation is dynamically regulated by DNA-PK and PPP-family protein phosphatases. DNA Repair (Amst) 2017; 54:30-39. [PMID: 28448822 DOI: 10.1016/j.dnarep.2017.03.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 02/28/2017] [Accepted: 03/24/2017] [Indexed: 11/16/2022]
Abstract
The maintenance of genomic stability is essential for cellular viability and the prevention of diseases such as cancer. Human single-stranded DNA-binding protein 1 (hSSB1) is a protein with roles in the stabilisation and restart of stalled DNA replication forks, as well as in the repair of oxidative DNA lesions and double-strand DNA breaks. In the latter process, phosphorylation of threonine 117 by the ATM kinase is required for hSSB1 stability and efficient DNA repair. The regulation of hSSB1 in other DNA repair pathways has however remained unclear. Here we report that hSSB1 is also directly phosphorylated by DNA-PK at serine residue 134. While this modification is largely suppressed in undamaged cells by PPP-family protein phosphatases, S134 phosphorylation is enhanced following the disruption of replication forks and promotes cellular survival. Together, these data thereby represent a novel mechanism for hSSB1 regulation following the inhibition of replication.
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Affiliation(s)
- Nicholas W Ashton
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, 37 Kent Street, Woolloongabba 4102, QLD, Australia.
| | - Nicolas Paquet
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, 37 Kent Street, Woolloongabba 4102, QLD, Australia.
| | - Sally L Shirran
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK.
| | - Emma Bolderson
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, 37 Kent Street, Woolloongabba 4102, QLD, Australia.
| | - Ruvini Kariawasam
- School of Science and Health, University of Western Sydney, Locked Bag 1797, Penrith 2751, NSW, Australia.
| | - Christine Touma
- School of Science and Health, University of Western Sydney, Locked Bag 1797, Penrith 2751, NSW, Australia.
| | - Azadeh Fallahbaghery
- School of Science and Health, University of Western Sydney, Locked Bag 1797, Penrith 2751, NSW, Australia.
| | - Roland Gamsjaeger
- School of Science and Health, University of Western Sydney, Locked Bag 1797, Penrith 2751, NSW, Australia.
| | - Liza Cubeddu
- School of Science and Health, University of Western Sydney, Locked Bag 1797, Penrith 2751, NSW, Australia.
| | - Catherine Botting
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, UK.
| | - Pamela M Pollock
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, 37 Kent Street, Woolloongabba 4102, QLD, Australia.
| | - Kenneth J O'Byrne
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, 37 Kent Street, Woolloongabba 4102, QLD, Australia.
| | - Derek J Richard
- School of Biomedical Research, Institute of Health and Biomedical Innovation at the Translational Research Institute, Queensland University of Technology, 37 Kent Street, Woolloongabba 4102, QLD, Australia.
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26
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Nagasawa H, Lin YF, Kato TA, Brogan JR, Shih HY, Kurimasa A, Bedford JS, Chen BPC, Little JB. Coordination of the Ser2056 and Thr2609 Clusters of DNA-PKcs in Regulating Gamma Rays and Extremely Low Fluencies of Alpha-Particle Irradiation to G 0/G 1 Phase Cells. Radiat Res 2017; 187:259-267. [PMID: 28118114 DOI: 10.1667/rr14679.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The catalytic subunit of DNA dependent protein kinase (DNA-PKcs) and its kinase activity are critical for mediation of non-homologous end-joining (NHEJ) of DNA double-strand breaks (DSB) in mammalian cells after gamma-ray irradiation. Additionally, DNA-PKcs phosphorylations at the T2609 cluster and the S2056 cluster also affect DSB repair and cellular sensitivity to gamma radiation. Previously we reported that phosphorylations within these two regions affect not only NHEJ but also homologous recombination repair (HRR) dependent DSB repair. In this study, we further examine phenotypic effects on cells bearing various combinations of mutations within either or both regions. Effects studied included cell killing as well as chromosomal aberration induction after 0.5-8 Gy gamma-ray irradiation delivered to synchronized cells during the G0/G1 phase of the cell cycle. Blocking phosphorylation within the T2609 cluster was most critical regarding sensitization and depended on the number of available phosphorylation sites. It was also especially interesting that only one substitution of alanine in each of the two clusters separately abolished the restoration of wild-type sensitivity by DNA-PKcs. Similar patterns were seen for induction of chromosomal aberrations, reflecting their connection to cell killing. To study possible change in coordination between HRR and NHEJ directed repair in these DNA-PKcs mutant cell lines, we compared the induction of sister chromatid exchanges (SCEs) by very low fluencies of alpha particles with mutant cells defective in the HRR pathway that is required for induction of SCEs. Levels of true SCEs induced by very low fluence of alpha-particle irradiation normally seen in wild-type cells were only slightly decreased in the S2056 cluster mutants, but were completely abolished in the T2609 cluster mutants and were indistinguishable from levels seen in HRR deficient cells. Again, a single substitution in the S2056 together with a single substitution in the T2609 cluster abolished SCE formation and thus also effectively interferes with HRR.
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Affiliation(s)
- Hatsumi Nagasawa
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523
| | - Yu-Fen Lin
- b Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Takamitsu A Kato
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523
| | - John R Brogan
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523
| | - Hung-Ying Shih
- b Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Akihiro Kurimasa
- c Tohoku Medical and Pharmaceutical University, Sendai, Japan, 981-8558; and
| | - Joel S Bedford
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523
| | - Benjamin P C Chen
- b Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - John B Little
- d Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, Massachusetts 02115
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27
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Hu B, Wang X, Hu S, Ying X, Wang P, Zhang X, Wang J, Wang H, Wang Y. miR-21-mediated Radioresistance Occurs via Promoting Repair of DNA Double Strand Breaks. J Biol Chem 2017; 292:3531-3540. [PMID: 28096467 DOI: 10.1074/jbc.m116.772392] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 01/05/2017] [Indexed: 12/31/2022] Open
Abstract
miR-21, as an oncogene that overexpresses in most human tumors, is involved in radioresistance; however, the mechanism remains unclear. Here, we demonstrate that miR-21-mediated radioresistance occurs through promoting repair of DNA double strand breaks, which includes facilitating both non-homologous end-joining (NHEJ) and homologous recombination repair (HRR). The miR-21-promoted NHEJ occurs through targeting GSK3B (a novel target of miR-21), which affects the CRY2/PP5 pathway and in turn increases DNA-PKcs activity. The miR-21-promoted HRR occurs through targeting both GSK3B and CDC25A (a known target of miR-21), which neutralizes the effects of targeting GSK3B-induced CDC25A increase because GSK3B promotes degradation of both CDC25A and cyclin D1, but CDC25A and cyclin D1 have an opposite effect on HRR. A negative correlation of expression levels between miR-21 and GSK3β exists in a subset of human tumors. Our results not only elucidate miR-21-mediated radioresistance, but also provide potential new targets for improving radiotherapy.
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Affiliation(s)
- Baocheng Hu
- Department of Radiation Oncology, Emory University School of Medicine, Winship Cancer Institute of Emory University, Atlanta, Georgia 30322
| | - Xiang Wang
- Department of Radiation Oncology, Emory University School of Medicine, Winship Cancer Institute of Emory University, Atlanta, Georgia 30322
| | - Shuofeng Hu
- Beijing Institute of Basic Medical Sciences, Beijing 100850, China
| | - Xiaomin Ying
- Beijing Institute of Basic Medical Sciences, Beijing 100850, China
| | - Ping Wang
- Department of Radiation Oncology, Emory University School of Medicine, Winship Cancer Institute of Emory University, Atlanta, Georgia 30322
| | - Xiangming Zhang
- Department of Radiation Oncology, Emory University School of Medicine, Winship Cancer Institute of Emory University, Atlanta, Georgia 30322
| | - Jian Wang
- Department of Radiation Oncology, Emory University School of Medicine, Winship Cancer Institute of Emory University, Atlanta, Georgia 30322
| | - Hongyan Wang
- Department of Radiation Oncology, Emory University School of Medicine, Winship Cancer Institute of Emory University, Atlanta, Georgia 30322
| | - Ya Wang
- Department of Radiation Oncology, Emory University School of Medicine, Winship Cancer Institute of Emory University, Atlanta, Georgia 30322.
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28
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Liu Y, Li Y, Lu X. Regulators in the DNA damage response. Arch Biochem Biophys 2016; 594:18-25. [PMID: 26882840 DOI: 10.1016/j.abb.2016.02.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 02/11/2016] [Accepted: 02/12/2016] [Indexed: 01/05/2023]
Abstract
Maintenance of genome integrity is essential for the proper function of all cells and organisms. In response to both endogenous and exogenous DNA damaging agents, mammalian cells have evolved a delicate system to sense DNA damage, stop cell cycle progression, modulate cell metabolism, repair damaged DNA, and induce programmed cell death if the damage is too severe. This coordinated global signaling network, namely the DNA damage response (DDR), ensures the genome stability under DNA damaging stress. A variety of regulators have been shown to modulate the activity and levels of key proteins in the DDR, including kinases, phosphatases, ubiquitin ligases, deubiquitinases, and other protein modifying enzymes. Epigenetic regulators, particularly microRNAs and long noncoding RNAs, have been emerging as an important payer of regulation in addition to canonical DNA damage signaling proteins. In this review, we will discuss the functional interaction between the regulators and their targets in the DDR.
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Affiliation(s)
- Yunhua Liu
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
| | - Yujing Li
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
| | - Xiongbin Lu
- Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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29
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Zheng X, Zhang L, Jin B, Zhang F, Zhang D, Cui L. Knockdown of protein phosphatase 5 inhibits ovarian cancer growth in vitro. Oncol Lett 2015; 11:168-172. [PMID: 26870184 DOI: 10.3892/ol.2015.3828] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 09/04/2015] [Indexed: 11/06/2022] Open
Abstract
Ovarian cancer is the most common cause of gynecological cancer-related mortality. Serine/threonine protein phosphatase 5 (PP5, PPP5C) has been recognized to be involved in the regulation of multiple cellular signaling cascades that control diverse cellular processes, including cell growth, differentiation, proliferation, motility and apoptosis. In this study, to evaluate the functional role of PP5 in ovarian cancer cells, lentivirus-mediated RNA interference (RNAi) was applied to silence PPP5C in the human ovarian cancer cell line CAOV-3. Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell colony forming ability was measured by colony formation. Cell cycle progression was determined by propidium iodide staining and flow cytometry. The results demonstrated that lentivirus-mediated RNAi specifically suppressed the expression of PPP5C at the mRNA and protein levels in CAOV-3 cells. Further investigations revealed that PP5 knockdown significantly inhibited the proliferation and colony formation of CAOV-3 cells. Moreover, the cell cycle of CAOV-3 cells was arrested at the G0/G1 phase following PP5 knockdown. This study highlights the crucial role of PP5 in promoting ovarian cancer cell proliferation, and provides a foundation for further study into the clinical potential of lentiviral-mediated delivery of PP5 RNAi therapy for the treatment of ovarian cancer.
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Affiliation(s)
- Xiaojiao Zheng
- Department of Gynaecology and Obstetrics, Ningbo First Hospital, Ningbo, Zhejiang 315010, P.R. China
| | - Lianxiao Zhang
- Department of Gynaecology and Obstetrics, Ningbo First Hospital, Ningbo, Zhejiang 315010, P.R. China
| | - Bohong Jin
- Department of Gynaecology and Obstetrics, Ningbo First Hospital, Ningbo, Zhejiang 315010, P.R. China
| | - Fubin Zhang
- Department of Gynaecology and Obstetrics, Ningbo First Hospital, Ningbo, Zhejiang 315010, P.R. China
| | - Duoyi Zhang
- Department of Gynaecology and Obstetrics, Ningbo First Hospital, Ningbo, Zhejiang 315010, P.R. China
| | - Lining Cui
- Department of Gynaecology and Obstetrics, Ningbo First Hospital, Ningbo, Zhejiang 315010, P.R. China
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Wu L, Zhang J, Wu H, Han E. DNA-PKcs interference sensitizes colorectal cancer cells to a mTOR kinase inhibitor WAY-600. Biochem Biophys Res Commun 2015; 466:547-53. [PMID: 26381179 DOI: 10.1016/j.bbrc.2015.09.068] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 09/11/2015] [Indexed: 10/23/2022]
Abstract
Colorectal cancer (CRC) is one leading contributor of cancer-related mortalities. Mammalian target of rapamycin (mTOR), existing in two complexes (mTORC1/2), is a valuable target for possible CRC interference. In the current study, we showed that WAY-600, a potent mTOR inhibitor, only exerted moderate activity against primary and HT-29 CRC cells. We proposed that DNA-dependent protein kinase catalytic subunit (DNA-PKcs) could be the major resistance factor of WAY-600 in CRC cells. DNA-PKcs inhibitors, including NU7026 and NU7441, dramatically enhanced WAY-600-induced cytotoxic and pro-apoptotic effect against the CRC cells. Further, WAY-600-exerted cytotoxicity was significantly increased in DNA-PKcs-silenced (by targeted siRNA/shRNA) CRC cells, but was attenuated with DNA-PKcs overexpression. Our evidence suggested that DNA-PKcs Thr-2609 phosphorylation might be critical for WAY-600's resistance. Mutation of this site through introducing a dominant negative DNA-PKcs (T2609A) dramatically potentiated WAY-600's sensitivity in HT-29 cells. Meanwhile, overexpression of protein phosphatase 5 (PP5) dephosphorylated DNA-PKcs at Thr-2609, and significantly increased WAY-600's sensitivity in HT-29 cells. In vivo, WAY-600-induced anti-HT-29 xenograft growth activity was significantly potentiated with NU7026 co-administration. These results suggest that DNA-PKcs could be the major resistance factor of WAY-600 in CRC cells.
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Affiliation(s)
- Ling Wu
- Gastrointestinal Surgery, Tianjin Baodi Hospital, Tianjin, 301800, China
| | - Jiansheng Zhang
- Gastrointestinal Surgery, Tianjin Baodi Hospital, Tianjin, 301800, China
| | - Huiguo Wu
- Gastrointestinal Surgery, Tianjin Baodi Hospital, Tianjin, 301800, China
| | - Enkun Han
- Gastrointestinal Surgery, Tianjin Baodi Hospital, Tianjin, 301800, China.
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Measles Virus Infection Inactivates Cellular Protein Phosphatase 5 with Consequent Suppression of Sp1 and c-Myc Activities. J Virol 2015; 89:9709-18. [PMID: 26157124 DOI: 10.1128/jvi.00825-15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 07/02/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Measles virus (MeV) causes several unique syndromes, including transient immunosuppression. To clarify the cellular responses to MeV infection, we previously analyzed a MeV-infected epithelial cell line and a lymphoid cell line by microarray and showed that the expression of numerous genes was up- or downregulated in the epithelial cells. In particular, there was a characteristic comprehensive downregulation of housekeeping genes during late stage infection. To identify the mechanism underlying this phenomenon, we examined the phosphorylation status of transcription factors and kinase/phosphatase activities in epithelial cells after infection. MeV infection inactivated cellular protein phosphatase 5 (PP5) that consequently inactivated DNA-dependent protein kinase, which reduced Sp1 phosphorylation levels, and c-Myc degradation, both of which downregulated the expression of many housekeeping genes. In addition, intracellular accumulation of viral nucleocapsid inactivated PP5 and subsequent downstream responses. These findings demonstrate a novel strategy of MeV during infection, which causes the collapse of host cellular functions. IMPORTANCE Measles virus (MeV) is one of the most important pathogens in humans. We previously showed that MeV infection induces the comprehensive downregulation of housekeeping genes in epithelial cells. By examining this phenomenon, we clarified the molecular mechanism underlying the constitutive expression of housekeeping genes in cells, which is maintained by cellular protein phosphatase 5 (PP5) and DNA-dependent protein kinase. We also demonstrated that MeV targets PP5 for downregulation in epithelial cells. This is the first report to show how MeV infection triggers a reduction in overall cellular functions of infected host cells. Our findings will help uncover unique pathogenicities caused by MeV.
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Selective activators of protein phosphatase 5 target the auto-inhibitory mechanism. Biosci Rep 2015; 35:BSR20150042. [PMID: 26182372 PMCID: PMC4721540 DOI: 10.1042/bsr20150042] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 03/06/2015] [Indexed: 12/18/2022] Open
Abstract
This paper describes the identification of compounds, which stimulate the activity of the protein phosphatase PPH-5 and addresses the influence of the identified compounds on the enzymatic properties and the potential mechanism of their action. Protein phosphatase 5 (PP5) is an evolutionary conserved serine/threonine phosphatase. Its dephosphorylation activity modulates a diverse set of cellular factors including protein kinases and the microtubule-associated tau protein involved in neurodegenerative disorders. It is auto-regulated by its heat-shock protein (Hsp90)-interacting tetratricopeptide repeat (TPR) domain and its C-terminal α-helix. In the present study, we report the identification of five specific PP5 activators [PP5 small-molecule activators (P5SAs)] that enhance the phosphatase activity up to 8-fold. The compounds are allosteric modulators accelerating efficiently the turnover rate of PP5, but do barely affect substrate binding or the interaction between PP5 and the chaperone Hsp90. Enzymatic studies imply that the compounds bind to the phosphatase domain of PP5. For the most promising compound crystallographic comparisons of the apo PP5 and the PP5–P5SA-2 complex indicate a relaxation of the auto-inhibited state of PP5. Residual electron density and mutation analyses in PP5 suggest activator binding to a pocket in the phosphatase/TPR domain interface, which may exert regulatory functions. These compounds thus may expose regulatory mechanisms in the PP5 enzyme and serve to develop optimized activators based on these scaffolds.
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Serine/Threonine Protein Phosphatase-5 Accelerates Cell Growth and Migration in Human Glioma. Cell Mol Neurobiol 2015; 35:669-77. [DOI: 10.1007/s10571-015-0162-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 01/30/2015] [Indexed: 11/24/2022]
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Knockdown of PPP5C inhibits growth of hepatocellular carcinoma cells in vitro. Appl Biochem Biotechnol 2014; 175:526-34. [PMID: 25326185 DOI: 10.1007/s12010-014-1281-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 09/30/2014] [Indexed: 02/07/2023]
Abstract
Ser/Thr protein phosphatase 5 (PPP5C) has been reported to participate in tumor progression. However, its functional role in hepatocellular carcinoma (HCC) remains unknown yet. In this study, we firstly evaluated the expression levels of PPP5C in six HCC cell lines by real-time PCR and found that PPP5C was widely expressed in HCC cells. To explore the role of PPP5C in HCC cell growth, lentivirus-mediated short hairpin RNA (shRNA) was employed to silence PPP5C expression in HepG2 and Bel-7404 cells. The expression of PPP5C was significantly downregulated in PPP5C knockdown cells. Knockdown of PPP5C markedly suppressed the proliferation and colony formation ability of HCC cells. Moreover, cell cycle analysis showed that PPP5C depletion in HepG2 cells led to G0/G1 phase and G2/M phase arrest. We demonstrate for the first time that PPP5C is essential for growth of HCC cells, which suggests that inhibition of PPP5C by RNAi may be a potential therapeutic strategy for the treatment of HCC.
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Swingle MR, Honkanen RE. Development and validation of a robust and sensitive assay for the discovery of selective inhibitors for serine/threonine protein phosphatases PP1α (PPP1C) and PP5 (PPP5C). Assay Drug Dev Technol 2014; 12:481-96. [PMID: 25383722 PMCID: PMC4229695 DOI: 10.1089/adt.2014.603] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Protein phosphatase types 1 α (PP1α/PPP1C) and 5 (PP5/PPP5C) are members of the PPP family of serine/threonine protein phosphatases. PP1 and PP5 share a common catalytic mechanism, and several natural compounds, including okadaic acid, microcystin, and cantharidin, act as strong inhibitors of both enzymes. However, to date there have been no reports of compounds that can selectively inhibit PP1 or PP5, and specific or highly selective inhibitors for either PP1 or PP5 are greatly desired by both the research and pharmaceutical communities. Here we describe the development and optimization of a sensitive and robust (representative PP5C assay data: Z'=0.93; representative PP1Cα assay data: Z'=0.90) fluorescent phosphatase assay that can be used to simultaneously screen chemical libraries and natural product extracts for the presence of catalytic inhibitors of PP1 and PP5.
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Affiliation(s)
- Mark R Swingle
- Department of Biochemistry and Molecular Biology, College of Medicine, University of South Alabama , Mobile, Alabama
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36
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Hu K, Li W, Gao J, Liu Q, Wang H, Wang Y, Sang J. Role of Ppt1 in multiple stress responses in Candida albicans. ACTA ACUST UNITED AC 2014. [DOI: 10.1007/s11434-014-0552-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Abstract
The prevalence of diabetes is increasing rapidly worldwide. A cardinal feature of most forms of diabetes is the lack of insulin-producing capability, due to the loss of insulin-producing β-cells, impaired glucose-sensitive insulin secretion from the β-cell, or a combination thereof, the reasons for which largely remain elusive. Reversible phosphorylation is an important and versatile mechanism for regulating the biological activity of many intracellular proteins, which, in turn, controls a variety of cellular functions. For instance, significant changes in protein kinase activities and in protein phosphorylation patterns occur subsequent to the stimulation of insulin release by glucose. Therefore, the molecular mechanisms regulating the phosphorylation of proteins involved in the insulin secretory process by the β-cell have been extensively investigated. However, far less is known about the role and regulation of protein dephosphorylation by various protein phosphatases. Herein, we review extant data implicating serine/threonine and tyrosine phosphatases in various aspects of healthy and diabetic islet biology, ranging from control of hormonal stimulus-secretion coupling to mitogenesis and apoptosis.
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Affiliation(s)
- Henrik Ortsäter
- Biovation Park TelgeSödertälje, SwedenResearch UnitSödertälje Hospital, SE-152 86 Södertälje, SwedenDegenerative Disease ProgramSanford-Burnham Medical Research Institute, Del E. Webb Neuroscience, Aging and Stem Cell Research Center, 10901 North Torrey Pines Road, La Jolla, California 92037, USADepartment of Biochemistry and Molecular BiologyCollege of Medicine, University of South Alabama, Mobile, Alabama 36688, USADepartment of Internal MedicineSödertälje Hospital, Södertälje, SwedenBiovation Park TelgeSödertälje, SwedenResearch UnitSödertälje Hospital, SE-152 86 Södertälje, SwedenDegenerative Disease ProgramSanford-Burnham Medical Research Institute, Del E. Webb Neuroscience, Aging and Stem Cell Research Center, 10901 North Torrey Pines Road, La Jolla, California 92037, USADepartment of Biochemistry and Molecular BiologyCollege of Medicine, University of South Alabama, Mobile, Alabama 36688, USADepartment of Internal MedicineSödertälje Hospital, Södertälje, Sweden
| | - Nina Grankvist
- Biovation Park TelgeSödertälje, SwedenResearch UnitSödertälje Hospital, SE-152 86 Södertälje, SwedenDegenerative Disease ProgramSanford-Burnham Medical Research Institute, Del E. Webb Neuroscience, Aging and Stem Cell Research Center, 10901 North Torrey Pines Road, La Jolla, California 92037, USADepartment of Biochemistry and Molecular BiologyCollege of Medicine, University of South Alabama, Mobile, Alabama 36688, USADepartment of Internal MedicineSödertälje Hospital, Södertälje, Sweden
| | - Richard E Honkanen
- Biovation Park TelgeSödertälje, SwedenResearch UnitSödertälje Hospital, SE-152 86 Södertälje, SwedenDegenerative Disease ProgramSanford-Burnham Medical Research Institute, Del E. Webb Neuroscience, Aging and Stem Cell Research Center, 10901 North Torrey Pines Road, La Jolla, California 92037, USADepartment of Biochemistry and Molecular BiologyCollege of Medicine, University of South Alabama, Mobile, Alabama 36688, USADepartment of Internal MedicineSödertälje Hospital, Södertälje, Sweden
| | - Åke Sjöholm
- Biovation Park TelgeSödertälje, SwedenResearch UnitSödertälje Hospital, SE-152 86 Södertälje, SwedenDegenerative Disease ProgramSanford-Burnham Medical Research Institute, Del E. Webb Neuroscience, Aging and Stem Cell Research Center, 10901 North Torrey Pines Road, La Jolla, California 92037, USADepartment of Biochemistry and Molecular BiologyCollege of Medicine, University of South Alabama, Mobile, Alabama 36688, USADepartment of Internal MedicineSödertälje Hospital, Södertälje, SwedenBiovation Park TelgeSödertälje, SwedenResearch UnitSödertälje Hospital, SE-152 86 Södertälje, SwedenDegenerative Disease ProgramSanford-Burnham Medical Research Institute, Del E. Webb Neuroscience, Aging and Stem Cell Research Center, 10901 North Torrey Pines Road, La Jolla, California 92037, USADepartment of Biochemistry and Molecular BiologyCollege of Medicine, University of South Alabama, Mobile, Alabama 36688, USADepartment of Internal MedicineSödertälje Hospital, Södertälje, SwedenBiovation Park TelgeSödertälje, SwedenResearch UnitSödertälje Hospital, SE-152 86 Södertälje, SwedenDegenerative Disease ProgramSanford-Burnham Medical Research Institute, Del E. Webb Neuroscience, Aging and Stem Cell Research Center, 10901 North Torrey Pines Road, La Jolla, California 92037, USADepartment of Biochemistry and Molecular BiologyCollege of Medicine, University of South Alabama, Mobile, Alabama 36688, USADepartment of Internal MedicineSödertälje Hospital, Södertälje, Sweden
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Radiation sensitivity of human and murine peripheral blood lymphocytes, stem and progenitor cells. Biochim Biophys Acta Rev Cancer 2014; 1846:121-9. [PMID: 24797212 DOI: 10.1016/j.bbcan.2014.04.009] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 04/02/2014] [Accepted: 04/26/2014] [Indexed: 11/21/2022]
Abstract
Immunodeficiency is a severe side effect of radiation therapy, notably at high radiation doses. It may also impact healthy individuals exposed to environmental ionizing radiation. Although it is believed to result from cytotoxicity of bone marrow cells and of immunocompetent cells in the peripheral blood, the response of distinct bone marrow and blood cell subpopulations following exposure to ionizing radiation is not yet fully explored. In this review, we aim to compile the knowledge on radiation sensitivity of immunocompetent cells and to summarize data from bone marrow and peripheral blood cells derived from mouse and human origin. In addition, we address the radiation response of blood stem and progenitor cells. The data indicate that stem cells, T helper cells, cytotoxic T cells, monocytes, neutrophils and, at a high degree, B cells display a radiation sensitive phenotype while regulatory T cells, macrophages, dendritic cells and natural killer cells appear to be more radioresistant. No conclusive data are available for basophil and eosinophil granulocytes. Erythrocytes and thrombocytes, but not their precursors, seem to be highly radioresistant. Overall, the data indicate considerable differences in radiosensitivity of bone marrow and blood normal and malignant cell populations, which are discussed in the light of differential radiation responses resulting in hematotoxicity and related clinical implications.
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Mazalouskas MD, Godoy-Ruiz R, Weber DJ, Zimmer DB, Honkanen RE, Wadzinski BE. Small G proteins Rac1 and Ras regulate serine/threonine protein phosphatase 5 (PP5)·extracellular signal-regulated kinase (ERK) complexes involved in the feedback regulation of Raf1. J Biol Chem 2013; 289:4219-32. [PMID: 24371145 DOI: 10.1074/jbc.m113.518514] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Serine/threonine protein phosphatase 5 (PP5, PPP5C) is known to interact with the chaperonin heat shock protein 90 (HSP90) and is involved in the regulation of multiple cellular signaling cascades that control diverse cellular processes, such as cell growth, differentiation, proliferation, motility, and apoptosis. Here, we identify PP5 in stable complexes with extracellular signal-regulated kinases (ERKs). Studies using mutant proteins reveal that the formation of PP5·ERK1 and PP5·ERK2 complexes partially depends on HSP90 binding to PP5 but does not require PP5 or ERK1/2 activity. However, PP5 and ERK activity regulates the phosphorylation state of Raf1 kinase, an upstream activator of ERK signaling. Whereas expression of constitutively active Rac1 promotes the assembly of PP5·ERK1/2 complexes, acute activation of ERK1/2 fails to influence the phosphatase-kinase interaction. Introduction of oncogenic HRas (HRas(V12)) has no effect on PP5-ERK1 binding but selectively decreases the interaction of PP5 with ERK2, in a manner that is independent of PP5 and MAPK/ERK kinase (MEK) activity, yet paradoxically requires ERK2 activity. Additional studies conducted with oncogenic variants of KRas4B reveal that KRas(L61), but not KRas(V12), also decreases the PP5-ERK2 interaction. The expression of wild type HRas or KRas proteins fails to reduce PP5-ERK2 binding, indicating that the effect is specific to HRas(V12) and KRas(L61) gain-of-function mutations. These findings reveal a novel, differential responsiveness of PP5-ERK1 and PP5-ERK2 interactions to select oncogenic Ras variants and also support a role for PP5·ERK complexes in regulating the feedback phosphorylation of PP5-associated Raf1.
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Affiliation(s)
- Matthew D Mazalouskas
- From the Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-6600
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40
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Gao P, Yoo SH, Lee KJ, Rosensweig C, Takahashi JS, Chen BP, Green CB. Phosphorylation of the cryptochrome 1 C-terminal tail regulates circadian period length. J Biol Chem 2013; 288:35277-86. [PMID: 24158435 PMCID: PMC3853276 DOI: 10.1074/jbc.m113.509604] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The Cryptochrome (CRY) proteins are critical components of the mammalian circadian clock and act to rhythmically repress the activity of the transcriptional activators CLOCK and BMAL1 at the heart of the clock mechanism. The CRY proteins are part of a large repressive complex, the components of which are not completely known. Using mass spectroscopy, we identified the catalytic subunit of DNA-dependent protein kinase as a CRY-interacting protein and found that loss or inhibition of this kinase results in circadian rhythms with abnormally long periods. We then identified serine 588 in the C-terminal tail of mouse CRY1 as a potential DNA-PK phosphorylation site but surprisingly found that the phosphomimetic mutation S588D also results in long period rhythms, similar to the loss of DNA-PK. Consistent with this, we found that phosphorylation of this site is increased in cells lacking DNA-PK, suggesting that DNA-PK negatively regulates the phosphorylation of this site most likely through indirect means. Furthermore, we found that phosphorylation of this site increases the stability of the CRY1 protein and prevents FBXL3-mediated degradation. The phosphorylation of this site is robustly rhythmic in mouse liver nuclei, peaking in the middle of the circadian day at a time when CRY1 levels are declining. Therefore, these data suggest a new role for the C-terminal tail of CRY1 in which phosphorylation rhythmically regulates CRY1 stability and contributes to the proper circadian period length.
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Affiliation(s)
- Peng Gao
- From the Department of Neuroscience, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Seung-Hee Yoo
- From the Department of Neuroscience, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
- the Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, and
| | - Kyung-Jong Lee
- the Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Clark Rosensweig
- From the Department of Neuroscience, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Joseph S. Takahashi
- From the Department of Neuroscience, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
- the Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, and
| | - Benjamin P. Chen
- the Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Carla B. Green
- From the Department of Neuroscience, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
- To whom correspondence should be addressed: Dept. of Neuroscience, ND4.124A, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9111. Tel.: 214-648-7433; Fax: 214-648-1801; E-mail:
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Jiang N, Shen Y, Fei X, Sheng K, Sun P, Qiu Y, Larner J, Cao L, Kong X, Mi J. Valosin-containing protein regulates the proteasome-mediated degradation of DNA-PKcs in glioma cells. Cell Death Dis 2013; 4:e647. [PMID: 23722536 PMCID: PMC3674378 DOI: 10.1038/cddis.2013.171] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
DNA-dependent protein kinase (DNA-PK) has an important role in the repair of DNA damage and regulates the radiation sensitivity of glioblastoma cells. The VCP (valosine-containing protein), a chaperone protein that regulates ubiquitin-dependent protein degradation, is phosphorylated by DNA-PK and recruited to DNA double-strand break sites to regulate DNA damage repair. However, it is not clear whether VCP is involved in DNA-PKcs (DNA-PK catalytic subunit) degradation or whether it regulates the radiosensitivity of glioblastoma. Our data demonstrated that DNA-PKcs was ubiquitinated and bound to VCP. VCP knockdown resulted in the accumulation of the DNA-PKcs protein in glioblastoma cells, and the proteasome inhibitor MG132 synergised this increase. As expected, this increase promoted the efficiency of DNA repair in several glioblastoma cell lines; in turn, this enhanced activity decreased the radiation sensitivity and prolonged the survival fraction of glioblastoma cells in vitro. Moreover, the VCP knockdown in glioblastoma cells reduced the survival time of the xenografted mice with radiation treatment relative to the control xenografted glioblastoma mice. In addition, the VCP protein was also downregulated in ∼25% of GBM tissues from patients (WHO, grade IV astrocytoma), and the VCP protein level was correlated with patient survival (R2=0.5222, P<0.05). These findings demonstrated that VCP regulates DNA-PKcs degradation and increases the sensitivity of GBM cells to radiation.
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Affiliation(s)
- N Jiang
- Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Detection and repair of ionizing radiation-induced DNA double strand breaks: new developments in nonhomologous end joining. Int J Radiat Oncol Biol Phys 2013; 86:440-9. [PMID: 23433795 DOI: 10.1016/j.ijrobp.2013.01.011] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 01/07/2013] [Indexed: 01/13/2023]
Abstract
DNA damage can occur as a result of endogenous metabolic reactions and replication stress or from exogenous sources such as radiation therapy and chemotherapy. DNA double strand breaks are the most cytotoxic form of DNA damage, and defects in their repair can result in genome instability, a hallmark of cancer. The major pathway for the repair of ionizing radiation-induced DSBs in human cells is nonhomologous end joining. Here we review recent advances on the mechanism of nonhomologous end joining, as well as new findings on its component proteins and regulation.
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Shimada M, Nakanishi M. Response to DNA damage: why do we need to focus on protein phosphatases? Front Oncol 2013; 3:8. [PMID: 23386996 PMCID: PMC3560363 DOI: 10.3389/fonc.2013.00008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Accepted: 01/09/2013] [Indexed: 01/07/2023] Open
Abstract
Eukaryotic cells are continuously threatened by unavoidable errors during normal DNA replication or various sources of genotoxic stresses that cause DNA damage or stalled replication. To maintain genomic integrity, cells have developed a coordinated signaling network, known as the DNA damage response (DDR). Following DNA damage, sensor molecules detect the presence of DNA damage and transmit signals to downstream transducer molecules. This in turn conveys the signals to numerous effectors, which initiate a large number of specific biological responses, including transient cell cycle arrest mediated by checkpoints, DNA repair, and apoptosis. It is recently becoming clear that dephosphorylation events are involved in keeping DDR factors inactive during normal cell growth. Moreover, dephosphorylation is required to shut off checkpoint arrest following DNA damage and has been implicated in the activation of the DDR. Spatial and temporal regulation of phosphorylation events is essential for the DDR, and fine-tuning of phosphorylation is partly mediated by protein phosphatases. While the role of kinases in the DDR has been well documented, the complex roles of protein dephosphorylation have only recently begun to be investigated. Therefore, it is important to focus on the role of phosphatases and to determine how their activity is regulated upon DNA damage. In this work, we summarize current knowledge on the involvement of serine/threonine phosphatases, especially the protein phosphatase 1, protein phosphatase 2A, and protein phosphatase Mg2+/Mn2+-dependent families, in the DDR.
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Affiliation(s)
- Midori Shimada
- Department of Cell Biology, Graduate School of Medical Sciences, Nagoya City University Nagoya, Japan
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Calderwood SK. Molecular cochaperones: tumor growth and cancer treatment. SCIENTIFICA 2013; 2013:217513. [PMID: 24278769 PMCID: PMC3820307 DOI: 10.1155/2013/217513] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 04/01/2013] [Indexed: 05/12/2023]
Abstract
Molecular chaperones play important roles in all cellular organisms by maintaining the proteome in an optimally folded state. They appear to be at a premium in cancer cells whose evolution along the malignant pathways requires the fostering of cohorts of mutant proteins that are employed to overcome tumor suppressive regulation. To function at significant rates in cells, HSPs interact with cochaperones, proteins that assist in catalyzing individual steps in molecular chaperoning as well as in posttranslational modification and intracellular localization. We review current knowledge regarding the roles of chaperones such as heat shock protein 90 (Hsp90) and Hsp70 and their cochaperones in cancer. Cochaperones are potential targets for cancer therapy in themselves and can be used to assess the likely prognosis of individual malignancies. Hsp70 cochaperones Bag1, Bag3, and Hop play significant roles in the etiology of some cancers as do Hsp90 cochaperones Aha1, p23, Cdc37, and FKBP1. Others such as the J domain protein family, HspBP1, TTC4, and FKBPL appear to be associated with more benign tumor phenotypes. The key importance of cochaperones for many pathways of protein folding in cancer suggests high promise for the future development of novel pharmaceutical agents.
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Affiliation(s)
- Stuart K. Calderwood
- Division of Molecular and Cellular Biology, Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, 99 Brookline Avenue, Boston, MA 02215, USA
- *Stuart K. Calderwood:
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Kwan HY, Fong WF, Yang Z, Yu ZL, Hsiao WLW. Inhibition of DNA-dependent protein kinase reduced palmitate and oleate-induced lipid accumulation in HepG2 cells. Eur J Nutr 2012. [DOI: 10.1007/s00394-012-0467-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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46
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Thompson LH. Recognition, signaling, and repair of DNA double-strand breaks produced by ionizing radiation in mammalian cells: the molecular choreography. Mutat Res 2012; 751:158-246. [PMID: 22743550 DOI: 10.1016/j.mrrev.2012.06.002] [Citation(s) in RCA: 261] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 06/09/2012] [Accepted: 06/16/2012] [Indexed: 12/15/2022]
Abstract
The faithful maintenance of chromosome continuity in human cells during DNA replication and repair is critical for preventing the conversion of normal diploid cells to an oncogenic state. The evolution of higher eukaryotic cells endowed them with a large genetic investment in the molecular machinery that ensures chromosome stability. In mammalian and other vertebrate cells, the elimination of double-strand breaks with minimal nucleotide sequence change involves the spatiotemporal orchestration of a seemingly endless number of proteins ranging in their action from the nucleotide level to nucleosome organization and chromosome architecture. DNA DSBs trigger a myriad of post-translational modifications that alter catalytic activities and the specificity of protein interactions: phosphorylation, acetylation, methylation, ubiquitylation, and SUMOylation, followed by the reversal of these changes as repair is completed. "Superfluous" protein recruitment to damage sites, functional redundancy, and alternative pathways ensure that DSB repair is extremely efficient, both quantitatively and qualitatively. This review strives to integrate the information about the molecular mechanisms of DSB repair that has emerged over the last two decades with a focus on DSBs produced by the prototype agent ionizing radiation (IR). The exponential growth of molecular studies, heavily driven by RNA knockdown technology, now reveals an outline of how many key protein players in genome stability and cancer biology perform their interwoven tasks, e.g. ATM, ATR, DNA-PK, Chk1, Chk2, PARP1/2/3, 53BP1, BRCA1, BRCA2, BLM, RAD51, and the MRE11-RAD50-NBS1 complex. Thus, the nature of the intricate coordination of repair processes with cell cycle progression is becoming apparent. This review also links molecular abnormalities to cellular pathology as much a possible and provides a framework of temporal relationships.
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Affiliation(s)
- Larry H Thompson
- Biology & Biotechnology Division, L452, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551-0808, United States.
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Hosing AS, Valerie NCK, Dziegielewski J, Brautigan DL, Larner JM. PP6 regulatory subunit R1 is bidentate anchor for targeting protein phosphatase-6 to DNA-dependent protein kinase. J Biol Chem 2012; 287:9230-9. [PMID: 22298787 DOI: 10.1074/jbc.m111.333708] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA-dependent protein kinase (DNA-PK) becomes activated in response to DNA double strand breaks, initiating repair by the non-homologous end joining pathway. DNA·PK complexes with the regulatory subunit SAPSR1 (R1) of protein phosphatase-6 (PP6). Knockdown of either R1 or PP6c prevents DNA-PK activation in response to ionizing radiation-induced DNA damage and radiosensitizes glioblastoma cells. Here, we demonstrate that R1 is necessary for and bridges the interaction between DNA-PK and PP6c. Using R1 deletion mutants, DNA-PK binding was mapped to two distinct regions of R1 spanning residues 1-326 and 522-700. Either region expressed alone was sufficient to bind DNA-PK, but only deletion of residues 1-326, not 522-700, eliminated interaction of R1 with DNA-PK. We assign 1-326 as the dominant domain and 522-700 as the supporting region. These results demonstrate that R1 acts as a bidentate anchor to DNA-PK and recruits PP6c. Targeting the dominant interface with small molecule or peptidomimetic inhibitors could specifically prevent activation of DNA-PK and thereby sensitize cells to ionizing radiation and other genotoxic agents.
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Affiliation(s)
- Amol S Hosing
- Department of Radiation Oncology, University of Virginia Health System, Charlottesville, Virginia 22908, USA
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Lee DH, Chowdhury D. What goes on must come off: phosphatases gate-crash the DNA damage response. Trends Biochem Sci 2011; 36:569-77. [PMID: 21930385 DOI: 10.1016/j.tibs.2011.08.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 08/18/2011] [Accepted: 08/19/2011] [Indexed: 12/24/2022]
Abstract
DNA-damage-induced phospho-signaling has been studied for decades, with a focus mainly on initiation of the signaling cascade, and the kinases activated by DNA lesions. It is widely accepted that the balance of phosphorylation needs to be restored and/or maintained by phosphatases, yet there have only been sporadic efforts to investigate the impact of phosphatases on DNA repair. Recent advances in phosphoproteomic strategies and implementation of large genetic screens indicate that these enzymes play pivotal roles in these signaling networks. Dephosphorylation of repair proteins is crucial for efficient DNA repair, and the recommencement of cell division post-repair. Here, we focus on serine/threonine phosphatases implicated in dephosphorylation of DNA repair factors, summarizing recent findings and speculating on untested roles of phosphatases in the DNA damage response.
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Affiliation(s)
- Dong-Hyun Lee
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA.
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Amable L, Grankvist N, Largen JW, Ortsäter H, Sjöholm Å, Honkanen RE. Disruption of serine/threonine protein phosphatase 5 (PP5:PPP5c) in mice reveals a novel role for PP5 in the regulation of ultraviolet light-induced phosphorylation of serine/threonine protein kinase Chk1 (CHEK1). J Biol Chem 2011; 286:40413-22. [PMID: 21921034 DOI: 10.1074/jbc.m111.244053] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PP5 is a ubiquitously expressed Ser/Thr protein phosphatase. High levels of PP5 have been observed in human cancers, and constitutive PP5 overexpression aids tumor progression in mouse models of tumor development. However, PP5 is highly conserved among species, and the roles of PP5 in normal tissues are not clear. Here, to help evaluate the biological actions of PP5, a Cre/loxP-conditional mouse line was generated. In marked contrast to the early embryonic lethality associated with the genetic disruption of other PPP family phosphatases (e.g. PP2A and PP4), intercrosses with mouse lines that ubiquitously express Cre recombinase starting early in development (e.g. MeuCre40 and ACTB-Cre) produced viable and fertile PP5-deficient mice. Phenotypic differences caused by the total disruption of PP5 were minor, suggesting that small molecule inhibitors of PP5 will not have widespread systemic toxicity. Examination of roles for PP5 in fibroblasts generated from PP5-deficient embryos (PP5(-/-) mouse embryonic fibroblasts) confirmed some known roles and identified new actions for PP5. PP5(-/-) mouse embryonic fibroblasts demonstrated increased sensitivity to UV light, hydroxyurea, and camptothecin, which are known activators of ATR (ataxia-telangiectasia and Rad3-related) kinase. Further study revealed a previously unrecognized role for PP5 downstream of ATR activation in a UV light-induced response. The genetic disruption of PP5 is associated with enhanced and prolonged phosphorylation of a single serine (Ser-345) on Chk1, increased phosphorylation of the p53 tumor suppressor protein (p53) at serine 18, and increased p53 protein levels. A comparable role for PP5 in the regulation of Chk1 phosphorylation was also observed in human cells.
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Affiliation(s)
- Lauren Amable
- Department of Biochemistry and Molecular Biology, College of Medicine, University of South Alabama, Mobile, Alabama 36688, USA
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Importance of PIKKs in NF-κB activation by genotoxic stress. Biochem Pharmacol 2011; 82:1371-83. [PMID: 21872579 DOI: 10.1016/j.bcp.2011.07.105] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Revised: 07/26/2011] [Accepted: 07/29/2011] [Indexed: 01/11/2023]
Abstract
Alteration of the genome integrity leads to the activation of a vast network of cellular responses named "DNA damage response". Three kinases from the phosphoinositide 3-kinase-like protein kinase family regulate this network; ATM and DNA-PK both activated by DNA double-strand breaks and ATR activated by replication blocks. "DNA damage response" pathway coordinates cell cycle arrest, DNA repair, and the activation of transcription factors such as p53 and NF-κB. It controls senescence/apoptosis/survival of the damaged cells. Cell death or survival result from a tightly regulated balance between antagonist pro- and anti-apoptotic signals. NF-κB is a key transcription factor involved in immunity, inflammation and cell transformation. When activated by DNA double-strand breaks, NF-κB has most often a pro-survival effect and thereof interferes with chemotherapy treatments that often rely on DNA damage to induce tumor cell death (i.e. topoisomerase inhibitors and ionizing radiation). NF-κB is thus an important pharmaceutical target. Agents leading to replication stress induce a pro-apoptotic NF-κB. The molecular mechanisms initiated by DNA lesions leading to NF-κB nuclear translocation have been extensively studied these last years. In this review, we will focus on ATM, ATR and DNA-PK functions both in the IKKα/IKKβ/NEMO-dependent or -independent signaling pathways and on the regulation they can exercise at the promoter level of NF-κB regulated genes.
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