1
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Todorovic M, Rivollier P, Wong AAWL, Wang Z, Pryyma A, Nguyen TT, Newell KC, Froelich J, Perrin DM. Rationally Designed Amanitins Achieve Enhanced Cytotoxicity. J Med Chem 2022; 65:10357-10376. [PMID: 35696491 DOI: 10.1021/acs.jmedchem.1c02226] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
For 70 years, α-amanitin, the most cytotoxic peptide in its class, has been without a synthetic rival; through synthesis, we address the structure-activity relationships to inform the design of new amatoxins and disclose analogues that are more cytotoxic than the natural product when evaluated on CHO, HEK293, and HeLa cells, whereas on liver-derived HepG2 cells, the same toxins show diminished cytotoxicity.
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Affiliation(s)
- Mihajlo Todorovic
- Chemistry Department, 2036 Main Mall, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T-1Z1, Canada
| | - Paul Rivollier
- Chemistry Department, 2036 Main Mall, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T-1Z1, Canada
| | - Antonio A W L Wong
- Chemistry Department, 2036 Main Mall, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T-1Z1, Canada
| | - Zhou Wang
- Chemistry Department, 2036 Main Mall, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T-1Z1, Canada
| | - Alla Pryyma
- Chemistry Department, 2036 Main Mall, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T-1Z1, Canada
| | - Tuan Trung Nguyen
- Chemistry Department, 2036 Main Mall, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T-1Z1, Canada
| | - Kayla C Newell
- Chemistry Department, 2036 Main Mall, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T-1Z1, Canada
| | - Juliette Froelich
- Chemistry Department, 2036 Main Mall, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T-1Z1, Canada
| | - David M Perrin
- Chemistry Department, 2036 Main Mall, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T-1Z1, Canada
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2
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Matinkhoo K, Pryyma A, Wong AAWL, Perrin DM. Synthesis and evaluation of " Ama-Flash", a photocaged amatoxin prodrug for light-activated RNA Pol II inhibition and cell death. Chem Commun (Camb) 2021; 57:9558-9561. [PMID: 34477193 DOI: 10.1039/d1cc03279h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Amanitin is used extensively as a research tool to inhibit RNA Pol II thereby implicating its role in mRNA transcription. Recently, amanitin has gained traction as a toxic payload for targeted therapy. Here we report the first-ever photocaged amanitin analog, that is non-toxic and can be pre-loaded into cells. Light provides a means to inhibit RNA Pol II and provoke cell death on-demand.
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Affiliation(s)
- Kaveh Matinkhoo
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada.
| | - Alla Pryyma
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada.
| | - Antonio A W L Wong
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada.
| | - David M Perrin
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada.
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3
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Lee TL, Lin PH, Chen PL, Hong JB, Wu CC. Hereditary Hearing Impairment with Cutaneous Abnormalities. Genes (Basel) 2020; 12:43. [PMID: 33396879 PMCID: PMC7823799 DOI: 10.3390/genes12010043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Revised: 12/25/2020] [Accepted: 12/26/2020] [Indexed: 12/15/2022] Open
Abstract
Syndromic hereditary hearing impairment (HHI) is a clinically and etiologically diverse condition that has a profound influence on affected individuals and their families. As cutaneous findings are more apparent than hearing-related symptoms to clinicians and, more importantly, to caregivers of affected infants and young individuals, establishing a correlation map of skin manifestations and their underlying genetic causes is key to early identification and diagnosis of syndromic HHI. In this article, we performed a comprehensive PubMed database search on syndromic HHI with cutaneous abnormalities, and reviewed a total of 260 relevant publications. Our in-depth analyses revealed that the cutaneous manifestations associated with HHI could be classified into three categories: pigment, hyperkeratosis/nail, and connective tissue disorders, with each category involving distinct molecular pathogenesis mechanisms. This outline could help clinicians and researchers build a clear atlas regarding the phenotypic features and pathogenetic mechanisms of syndromic HHI with cutaneous abnormalities, and facilitate clinical and molecular diagnoses of these conditions.
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Affiliation(s)
- Tung-Lin Lee
- Department of Medical Education, National Taiwan University Hospital, Taipei City 100, Taiwan;
| | - Pei-Hsuan Lin
- Department of Otolaryngology, National Taiwan University Hospital, Taipei 11556, Taiwan;
- Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei City 100, Taiwan;
| | - Pei-Lung Chen
- Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei City 100, Taiwan;
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei City 100, Taiwan
- Department of Medical Genetics, National Taiwan University Hospital, Taipei 10041, Taiwan
- Department of Internal Medicine, National Taiwan University Hospital, Taipei 10041, Taiwan
| | - Jin-Bon Hong
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei City 100, Taiwan
- Department of Dermatology, National Taiwan University Hospital, Taipei City 100, Taiwan
| | - Chen-Chi Wu
- Department of Otolaryngology, National Taiwan University Hospital, Taipei 11556, Taiwan;
- Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei City 100, Taiwan;
- Department of Medical Genetics, National Taiwan University Hospital, Taipei 10041, Taiwan
- Department of Medical Research, National Taiwan University Biomedical Park Hospital, Hsinchu City 300, Taiwan
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4
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Wang M, Chen Y, Guo Z, Yang C, Qi J, Fu Y, Chen Z, Chen P, Wang Y. Changes in the mitochondrial proteome in human hepatocytes in response to alpha-amanitin hepatotoxicity. Toxicon 2018; 156:34-40. [PMID: 30399359 DOI: 10.1016/j.toxicon.2018.11.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 10/20/2018] [Accepted: 11/01/2018] [Indexed: 01/16/2023]
Abstract
Amanitin-induced apoptosis is proposed to have a significant effect on the pathogenesis of liver damage. However, few reports have focused on proteome changes induced by α-amanitin (α-AMA). Here, we evaluated changes in mitochondrial proteins of hepatocytes in response to 2 μM α-AMA, a concentration at which α-AMA-induced cell damage could be rescued at cellular level by common clinical drugs. We found 56 proteins were differentially expressed in an α-AMA-treated group. Among them, 38 proteins were downregulated and 18 were upregulated. Downregulated functional proteins included importer TOMM40, respiratory chain component cytochrome C, and metabolic enzymes of citrate acid cycle such as malate dehydrogenase, which localize on the mitochondrial outer membrane, inner membrane and matrix respectively. Immunoblot analysis showed that α-AMA decreased mitochondrial import receptor subunit TOMM40 and cytochrome c accompanied by an increase in the cytosol although their total protein levels were not affected significantly. The mitochondrial membrane potential was also destroyed by α-AMA and was restored by the clinical drug silibinin. Immunofluorescence suggested that mitochondrial morphology did not change. Taken together, our results provide further insights into the toxic mechanism of α-AMA on hepatocytes.
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Affiliation(s)
- Mei Wang
- The Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, PR China
| | - Yu Chen
- The Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, PR China
| | - Zhen Guo
- The Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, PR China
| | - Changcheng Yang
- The Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, PR China
| | - Jiaomei Qi
- The Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, PR China
| | - Yujuan Fu
- The Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, PR China
| | - Zuohong Chen
- The Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, PR China
| | - Ping Chen
- The Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, PR China.
| | - Ying Wang
- The Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Sciences, Hunan Normal University, Changsha 410081, PR China.
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5
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Kasraian Z, Trompezinski S, Cario-André M, Morice-Picard F, Ged C, Jullie ML, Taieb A, Rezvani HR. Pigmentation abnormalities in nucleotide excision repair disorders: Evidence and hypotheses. Pigment Cell Melanoma Res 2018; 32:25-40. [PMID: 29938913 DOI: 10.1111/pcmr.12720] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 05/11/2018] [Accepted: 06/11/2018] [Indexed: 12/12/2022]
Abstract
Skin pigmentation abnormalities are manifested in several disorders associated with deficient DNA repair mechanisms such as nucleotide excision repair (NER) and double-strand break (DSB) diseases, a topic that has not received much attention up to now. Hereditary disorders associated with defective DNA repair are valuable models for understanding mechanisms that lead to hypo- and hyperpigmentation. Owing to the UV-associated nature of abnormal pigmentary manifestations, the outcome of the activated DNA damage response (DDR) network could be the effector signal for alterations in pigmentation, ultimately manifesting as pigmentary abnormalities in repair-deficient disorders. In this review, the role of the DDR network in the manifestation of pigmentary abnormalities in NER and DSB disorders is discussed with a special emphasis on NER disorders.
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Affiliation(s)
- Zeinab Kasraian
- NAOS, Aix en Provence, France.,Univ. Bordeaux, Inserm, BMGIC, UMR 1035, Bordeaux, France
| | | | - Muriel Cario-André
- Univ. Bordeaux, Inserm, BMGIC, UMR 1035, Bordeaux, France.,Centre de Référence pour les Maladies Rares de la Peau, CHU de Bordeaux, Bordeaux, France
| | - Fanny Morice-Picard
- Centre de Référence pour les Maladies Rares de la Peau, CHU de Bordeaux, Bordeaux, France.,Service de Dermatologie Adulte et Pédiatrique, CHU de Bordeaux, Bordeaux, France
| | - Cécile Ged
- Univ. Bordeaux, Inserm, BMGIC, UMR 1035, Bordeaux, France.,Centre de Référence pour les Maladies Rares de la Peau, CHU de Bordeaux, Bordeaux, France
| | | | - Alain Taieb
- Univ. Bordeaux, Inserm, BMGIC, UMR 1035, Bordeaux, France.,Centre de Référence pour les Maladies Rares de la Peau, CHU de Bordeaux, Bordeaux, France.,Service de Dermatologie Adulte et Pédiatrique, CHU de Bordeaux, Bordeaux, France
| | - Hamid Reza Rezvani
- Univ. Bordeaux, Inserm, BMGIC, UMR 1035, Bordeaux, France.,Centre de Référence pour les Maladies Rares de la Peau, CHU de Bordeaux, Bordeaux, France
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6
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Matinkhoo K, Pryyma A, Todorovic M, Patrick BO, Perrin DM. Synthesis of the Death-Cap Mushroom Toxin α-Amanitin. J Am Chem Soc 2018; 140:6513-6517. [PMID: 29561592 DOI: 10.1021/jacs.7b12698] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
α-Amanitin is an extremely toxic bicyclic octapeptide isolated from the death-cap mushroom, Amanita phalloides. As a potent inhibitor of RNA polymerase II, α-amanitin is toxic to eukaryotic cells. Recent interest in α-amanitin arises from its promise as a payload for antibody-drug conjugates. For over 60 years, A. phalloides has been the only source of α-amanitin. Here we report a synthesis of α-amanitin, which surmounts the key challenges for installing the 6-hydroxy-tryptathionine sulfoxide bridge, enantioselective synthesis of (2 S,3 R,4 R)-4,5-dihydroxy-isoleucine, and diastereoselective sulfoxidation.
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Affiliation(s)
- Kaveh Matinkhoo
- Chemistry Department , The University of British Columbia , 2036 Main Mall , Vancouver , British Columbia V6T-1Z1 , Canada
| | - Alla Pryyma
- Chemistry Department , The University of British Columbia , 2036 Main Mall , Vancouver , British Columbia V6T-1Z1 , Canada
| | - Mihajlo Todorovic
- Chemistry Department , The University of British Columbia , 2036 Main Mall , Vancouver , British Columbia V6T-1Z1 , Canada
| | - Brian O Patrick
- Chemistry Department , The University of British Columbia , 2036 Main Mall , Vancouver , British Columbia V6T-1Z1 , Canada
| | - David M Perrin
- Chemistry Department , The University of British Columbia , 2036 Main Mall , Vancouver , British Columbia V6T-1Z1 , Canada
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7
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Abstract
DNA is vulnerable to damage resulting from endogenous metabolites, environmental and dietary carcinogens, some anti-inflammatory drugs, and genotoxic cancer therapeutics. Cells respond to DNA damage by activating complex signalling networks that decide cell fate, promoting not only DNA repair and survival but also cell death. The decision between cell survival and death following DNA damage rests on factors that are involved in DNA damage recognition, and DNA repair and damage tolerance, as well as on factors involved in the activation of apoptosis, necrosis, autophagy and senescence. The pathways that dictate cell fate are entwined and have key roles in cancer initiation and progression. Furthermore, they determine the outcome of cancer therapy with genotoxic drugs. Understanding the molecular basis of these pathways is important not only for gaining insight into carcinogenesis, but also in promoting successful cancer therapy. In this Review, we describe key decision-making nodes in the complex interplay between cell survival and death following DNA damage.
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Affiliation(s)
- Wynand P Roos
- Institute of Toxicology, University Medical Center, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
| | - Adam D Thomas
- Institute of Toxicology, University Medical Center, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
| | - Bernd Kaina
- Institute of Toxicology, University Medical Center, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany
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8
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Cao W, Zhang JL, Feng DY, Liu XW, Li Y, Wang LF, Yao LB, Zhang H, Zhang J. The effect of adenovirus-conjugated NDRG2 on p53-mediated apoptosis of hepatocarcinoma cells through attenuation of nucleotide excision repair capacity. Biomaterials 2014; 35:993-1003. [PMID: 24383128 DOI: 10.1016/j.biomaterials.2013.09.096] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
NDRG2 mRNA and protein levels can be upregulated in a p53-dependent manner. NDRG2 enhances p53-mediated apoptosis, whereas overexpression of NDRG2 suppresses tumor cell growth, regardless of whether p53 is mutated. However, the complicated mechanism by which NDRG2 suppresses tumor cell growth and enhances apoptosis mediated by p53 is not fully understood. Here, we demonstrated that Ad-NDRG2 enhanced the apoptosis of HepG2 cells (wild-type p53). Additionally, Ad-NDRG2 combined with rAd-p53 enhanced the apoptosis of Huh7 cells (mutant p53) after chemotherapy, and the expression of the ERCC6 gene (Cockayne syndrome group B protein gene) was suppressed in this process. Ad-NDRG2 combined with rAd-p53 induced the apoptosis of tumor cells (HepG2 and Huh7 cells); however, apoptosis was attenuated after transfection with ERCC6. Our results indicate that Ad-NDRG2 enhances the p53-mediated apoptosis of hepatocarcinoma cells (HepG2 and Huh7) by attenuating the nucleotide excision repair capacity (i.e., by downregulating ERCC6), and ERCC6 is a NDRG2-inducible target gene that is involved in the p53-mediated apoptosis pathway.
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9
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McKay BC, Cabrita MA. Arresting transcription and sentencing the cell: the consequences of blocked transcription. Mech Ageing Dev 2013; 134:243-52. [PMID: 23542592 DOI: 10.1016/j.mad.2013.03.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/16/2013] [Accepted: 03/16/2013] [Indexed: 10/27/2022]
Abstract
Bulky DNA adducts induced by agents like ultraviolet light, cisplatin and oxidative metabolism pose a block to elongation by RNA polymerase II (RNAPII). The arrested RNAPII can initiate the repair of transcription-blocking DNA lesions by transcription-coupled nucleotide excision repair (TC-NER) to permit efficient recovery of mRNA synthesis while widespread sustained transcription blocks lead to apoptosis. Therefore, RNAPII serves as a processive DNA damage sensor that identifies transcription-blocking DNA lesions. Cockayne syndrome (CS) is an autosomal recessive disorder characterized by a complex phenotype that includes clinical photosensitivity, progressive neurological degeneration and premature-aging. CS is associated with defects in TC-NER and the recovery of mRNA synthesis, making CS cells exquisitely sensitive to a variety of DNA damaging agents. These defects in the coupling of repair and transcription appear to underlie some of the complex clinical features of CS. Recent insight into the consequences of blocked transcription and their relationship to CS will be discussed.
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Affiliation(s)
- Bruce C McKay
- Cancer Therapeutics Program, Ottawa Hospital Research Institute, Canada.
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10
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Phosphorylation of the transcription factor YY1 by CK2α prevents cleavage by caspase 7 during apoptosis. Mol Cell Biol 2011; 32:797-807. [PMID: 22184066 DOI: 10.1128/mcb.06466-11] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In this report, we describe the phosphorylation of Yin Yang 1 (YY1) in vitro and in vivo by CK2α (casein kinase II), a multifunctional serine/threonine protein kinase. YY1 is a ubiquitously expressed multifunctional zinc finger transcription factor implicated in regulation of many cellular and viral genes. The products of these genes are associated with cell growth, the cell cycle, development, and differentiation. Numerous studies have linked YY1 to tumorigenesis and apoptosis. YY1 is a target for cleavage by caspases in vitro and in vivo as well, but very little is known about the mechanisms that regulate its cleavage during apoptosis. Here, we identify serine 118 in the transactivation domain of YY1 as the site of CK2α phosphorylation, proximal to a caspase 7 cleavage site. CK2α inhibitors, as well as knockdown of CK2α by small interfering RNA, reduce S118 phosphorylation in vivo and enhance YY1 cleavage under apoptotic conditions, whereas increased CK2α activity by overexpression in vivo elevates S118 phosphorylation. A serine-to-alanine substitution at serine 118 also increases the cleavage of YY1 during apoptosis compared to wild-type YY1. Taken together, we have discovered a regulatory link between YY1 phosphorylation at serine 118 and regulation of its cleavage during programmed cell death.
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11
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Wang QE, Han C, Zhang B, Sabapathy K, Wani AA. Nucleotide excision repair factor XPC enhances DNA damage-induced apoptosis by downregulating the antiapoptotic short isoform of caspase-2. Cancer Res 2011; 72:666-75. [PMID: 22174370 DOI: 10.1158/0008-5472.can-11-2774] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
XPC protein is a critical DNA damage recognition factor in nucleotide excision repair for which genetic deficiency confers a predisposition to cancer. In this study, we show that XPC has a function that is independent of its canonical function in DNA repair, potentially altering the interpretation of how XPC deficiency leads to heightened cancer susceptibility. XPC enhances apoptosis induced by DNA damage in a p53 nullizygous background, acting downstream of mitochondrial permeabilization and upstream of caspase-9 activation in the DNA damage-induced apoptosis cascade. We found that deficiency in XPC upregulated production of the short isoform of caspase-2 (casp-2S). This upregulation occurred at both protein and mRNA levels through repression of the caspase-2 promoter by XPC protein. Targeted RNAi-mediated downregulation of casp-2S-enhanced UV-induced apoptosis as well as activation of caspase-9 and caspase-6 in XPC-deficient cells, but not in XPC-proficient cells. In addition, XPC overexpression in various p53-deficient cancer cells resistant to cisplatin improved their sensitivity to cisplatin-induced apoptosis. Given that casp-2S functions as an antiapoptotic protein, our findings suggest that XPC enhances DNA damage-induced apoptosis through inhibition of casp-2S transcription. Together, these findings offer a mechanistic foundation to overcome the resistance of highly prevalent p53-deficient tumors to cell death induced by DNA-damaging therapeutic agents, by targeting strategies that inhibit the expression or function of casp-2S.
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Affiliation(s)
- Qi-En Wang
- Department of Radiology, The Ohio State University, Columbus, Ohio 43210, USA.
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12
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Magdalan J, Piotrowska A, GomuŁkiewicz A, Sozański T, Podhorska-OkoŁów M, Szeląg A, Dzięgiel P. Benzylpenicyllin and acetylcysteine protection from α-amanitin-induced apoptosis in human hepatocyte cultures. ACTA ACUST UNITED AC 2011; 63:311-5. [DOI: 10.1016/j.etp.2010.02.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Revised: 02/07/2010] [Accepted: 02/15/2010] [Indexed: 11/16/2022]
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13
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Vrouwe MG, Pines A, Overmeer RM, Hanada K, Mullenders LHF. UV-induced photolesions elicit ATR-kinase-dependent signaling in non-cycling cells through nucleotide excision repair-dependent and -independent pathways. J Cell Sci 2011; 124:435-46. [PMID: 21224401 DOI: 10.1242/jcs.075325] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Activation of signaling pathways by UV radiation is a key event in the DNA damage response and initiated by different cellular processes. Here we show that non-cycling cells proficient in nucleotide excision repair (NER) initiate a rapid but transient activation of the damage response proteins p53 and H2AX; by contrast, NER-deficient cells display delayed but persistent signaling and inhibition of cell cycle progression upon release from G0 phase. In the absence of repair, UV-induced checkpoint activation coincides with the formation of single-strand DNA breaks by the action of the endonuclease Ape1. Although temporally distinct, activation of checkpoint proteins in NER-proficient and NER-deficient cells depends on a common pathway involving the ATR kinase. These data reveal that damage signaling in non-dividing cells proceeds via NER-dependent and NER-independent processing of UV photolesions through generation of DNA strand breaks, ultimately preventing the transition from G1 to S phase.
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Affiliation(s)
- Mischa G Vrouwe
- Department of Toxicogenetics, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands
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14
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Stubbert LJ, Smith JM, McKay BC. Decreased transcription-coupled nucleotide excision repair capacity is associated with increased p53- and MLH1-independent apoptosis in response to cisplatin. BMC Cancer 2010; 10:207. [PMID: 20470425 PMCID: PMC2889890 DOI: 10.1186/1471-2407-10-207] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Accepted: 05/14/2010] [Indexed: 01/22/2023] Open
Abstract
Background One of the most commonly used classes of anti-cancer drugs presently in clinical practice is the platinum-based drugs, including cisplatin. The efficacy of cisplatin therapy is often limited by the emergence of resistant tumours following treatment. Cisplatin resistance is multi-factorial but can be associated with increased DNA repair capacity, mutations in p53 or loss of DNA mismatch repair capacity. Methods RNA interference (RNAi) was used to reduce the transcription-coupled nucleotide excision repair (TC-NER) capacity of several prostate and colorectal carcinoma cell lines with specific defects in p53 and/or DNA mismatch repair. The effect of small inhibitory RNAs designed to target the CSB (Cockayne syndrome group B) transcript on TC-NER and the sensitivity of cells to cisplatin-induced apoptosis was determined. Results These prostate and colon cancer cell lines were initially TC-NER proficient and RNAi against CSB significantly reduced their DNA repair capacity. Decreased TC-NER capacity was associated with an increase in the sensitivity of tumour cells to cisplatin-induced apoptosis, even in p53 null and DNA mismatch repair-deficient cell lines. Conclusion The present work indicates that CSB and TC-NER play a prominent role in determining the sensitivity of tumour cells to cisplatin even in the absence of p53 and DNA mismatch repair. These results further suggest that CSB represents a potential target for cancer therapy that may be important to overcome resistance to cisplatin in the clinic.
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Affiliation(s)
- Lawton J Stubbert
- Cancer Therapeutics Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.
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15
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Magdalan J, Piotrowska A, Gomułkiewicz A, Sozański T, Szeląg A, Dziegięl P. Influence of commonly used clinical antidotes on antioxidant systems in human hepatocyte culture intoxicated with alpha-amanitin. Hum Exp Toxicol 2010; 30:38-43. [PMID: 20378659 DOI: 10.1177/0960327110368418] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
α-Amanitin (α-AMA) is the main toxin of Amanita phalloides and its subspecies (A. virosa and A. verna). The primary mechanism of α-AMA toxicity is associated with protein synthesis blocking in hepatocytes. Additionally, α-AMA exhibits prooxidant properties that may contribute to its severe hepatotoxicity. The aim of the present study was to assess the effect of α-AMA on lipid peroxidation and the activities of superoxide dismutase (SOD) and catalase (CAT) in human hepatocyte culture. The effects of benzylpenicillin (BPCN), N-acetyl-L-cysteine (ACC), and silibinin (SIL) on SOD and CAT activities and on lipid peroxidation in human hepatocyte culture intoxicated with α-AMA were also examined. In human hepatocyte culture, 48-hour exposure to α-AMA at a 2-μM concentration caused an increase in SOD activity, a reduction of CAT activity, and a significant increase in lipid peroxidation. Changes in SOD and CAT activity caused by α-AMA could probably enhance lipid peroxidation by increased generation of hydrogen peroxide combined with reduced detoxification of that oxygen radical. The addition of antidotes (ACC or SIL) to the culture medium provided more effective protection against lipid peroxidation in human hepatocytes intoxicated with α-AMA than the addition of BPCN, possessing no antioxidant properties.
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Affiliation(s)
- Jan Magdalan
- Department of Pharmacology, Wrocław Medical University, Mikulicza-Radeckiego 2, Wrocław, Poland
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16
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Lin CS, He PJ, Tsai NM, Li CH, Yang SC, Hsu WT, Wu MS, Wu CJ, Cheng TL, Liao KW. A potential role for Helicobacter pylori heat shock protein 60 in gastric tumorigenesis. Biochem Biophys Res Commun 2010; 392:183-9. [PMID: 20060384 DOI: 10.1016/j.bbrc.2010.01.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 01/05/2010] [Indexed: 01/06/2023]
Abstract
Helicobacter pylori has been found to promote the malignant process leading to gastric cancer. Heat shock protein 60 of H. pylori (HpHSP60) was previously been identified as a potent immunogene. This study investigates the role of HpHSP60 in gastric cancer carcinogenesis. The effect of HpHSP60 on cell proliferation, anti-death activity, angiogenesis and cell migration were explored. The results showed that HpHSP60 enhanced migration by gastric cancer cells and promoted tube formation by umbilical vein endothelial cells (HUVECs); however, HpHSP60 did not increase cell proliferation nor was this protein able to rescue gastric cancer cells from death. Moreover, the results also indicated HpHSP60 had different effects on AGS gastric cancer cells or THP-1 monocytic cells in terms of their expression of pro-inflammatory cytokines, which are known to be important to cancer development. We propose that HpHSP60 may trigger the initiation of carcinogenesis by inducing pro-inflammatory cytokine release and by promoting angiogenesis and metastasis. Thus, this extracellular pathogen-derived HSP60 is potentially a vigorous virulence factor that can act as a carcinogen during gastric tumorigenesis.
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Affiliation(s)
- Chen-Si Lin
- Department of Biological Science and Technology, National Chiao-Tung University, Hsin-Chu, Taiwan
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17
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The cyclin-dependent kinase inhibitor 5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole induces nongenotoxic, DNA replication-independent apoptosis of normal and leukemic cells, regardless of their p53 status. BMC Cancer 2009; 9:281. [PMID: 19674456 PMCID: PMC2743708 DOI: 10.1186/1471-2407-9-281] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Accepted: 08/12/2009] [Indexed: 11/15/2022] Open
Abstract
Background Current chemotherapy of human cancers focuses on the DNA damage pathway to induce a p53-mediated cellular response leading to either G1 arrest or apoptosis. However, genotoxic treatments may induce mutations and translocations that result in secondary malignancies or recurrent disease. In addition, about 50% of human cancers are associated with mutations in the p53 gene. Nongenotoxic activation of apoptosis by targeting specific molecular pathways thus provides an attractive therapeutic approach. Methods Normal and leukemic cells were evaluated for their sensitivity to 5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) through cell viability and caspase activation tests. The apoptotic pathway induced by DRB was analysed by immunfluorescence and immunoblot analysis. H2AX phosphorylation and cell cycle analysis were performed to study the dependance of apoptosis on DNA damage and DNA replication, respectively. To investigate the role of p53 in DRB-induced apoptosis, specific p53 inhibitors were used. Statistical analysis on cell survival was performed with the test of independence. Results Here we report that DRB, an inhibitor of the transcriptional cyclin-dependent kinases (CDKs) 7 and 9, triggers DNA replication-independent apoptosis in normal and leukemic human cells regardless of their p53 status and without inducing DNA damage. Our data indicate that (i) in p53-competent cells, apoptosis induced by DRB relies on a cytosolic accumulation of p53 and subsequent Bax activation, (ii) in the absence of p53, it may rely on p73, and (iii) it is independent of ATM and NBS1 proteins. Notably, even apoptosis-resistant leukemic cells such as Raji were sensitive to DRB. Conclusion Our results indicate that DRB represents a potentially useful cancer chemotherapeutic strategy that employs both the p53-dependent and -independent apoptotic pathways without inducing genotoxic stress, thereby decreasing the risk of secondary malignancies.
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Azuma M, Toyama R, Laver E, Dawid IB. Perturbation of rRNA Synthesis in the bap28 Mutation Leads to Apoptosis Mediated by p53 in the Zebrafish Central Nervous System. J Biol Chem 2006; 281:13309-13316. [PMID: 16531401 DOI: 10.1074/jbc.m601892200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Zebrafish is a powerful vertebrate model system for using forward genetics to elucidate mechanisms of early development. We have used chemical mutagenesis to screen for mutants that show defects in the CNS. Here we describe the isolation of the bap28 mutation that leads to abnormalities in the brain starting at midsomitogenesis stages. Mutant embryos display excess apoptosis primarily in the central nervous system (CNS) and die by days 6-7 after fertilization. The mutation was positionally cloned and shown to affect a gene that encodes a large protein with high similarity to the uncharacterized human protein BAP28 and lower similarity to yeast Utp10. Utp10 is a component of a nucleolar U3 small nucleolar RNA-containing RNP complex that is required for transcription of ribosomal DNA and for processing of 18 S rRNA. We show that zebrafish Bap28 likewise is required for rRNA transcription and processing, with a major effect on 18 S rRNA maturation. We suggest that bap28 is required for cell survival in the CNS through its role in rRNA synthesis and processing. Inhibition of p53 protein expression in bap28 mutants led to embryos with morphologically normal appearance, suggesting that p53 is involved in triggering apoptosis in the bap28 mutant CNS. The bap28 mutation provides a genetic approach to study the role of ribosome biogenesis in the development of a vertebrate embryo.
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Affiliation(s)
- Mizuki Azuma
- Laboratory of Molecular Genetics, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Reiko Toyama
- Laboratory of Molecular Genetics, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Elizabeth Laver
- Laboratory of Molecular Genetics, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Igor B Dawid
- Laboratory of Molecular Genetics, NICHD, National Institutes of Health, Bethesda, Maryland 20892.
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19
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Abstract
Aging of somatic cells can be defined as the gradual loss of the information embedded in the global and local properties of complex macromolecular networks. This loss of information may reflect the dynamic interplay between stochastic factors, such as the accumulation of unrepaired somatic damage, and gene-encoded programmatic responses. This would ultimately result in loss of function, impaired response to environmental challenge, and a progressively increased incidence of disease. Here the authors present the case for aging as a continuous battle between maintaining genomic integrity and ensuring sufficient cell functional mass. Focusing on aging of the liver in rodents, evidence is presented that normal aging is associated with a gradual accumulation of random alterations in the DNA of the genome as a consequence of imperfect DNA repair and a decrease in the rate of DNA damage-induced apoptosis. Apoptosis is the cell's genome maintenance mechanism of last resort and an imbalance towards apoptosis can contribute to manifestations of aging-related phenotypes, as exemplified by mouse models of premature aging due to genetic defects in genome maintenance. Prospects to reset the clock in this zero sum game between survival and the maintenance of phenotypic integrity will be discussed.
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Affiliation(s)
- Yousin Suh
- Department of Molecular Medicine and Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center, San Antonio, Texas 78425, USA.
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20
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Arima Y, Nitta M, Kuninaka S, Zhang D, Fujiwara T, Taya Y, Nakao M, Saya H. Transcriptional Blockade Induces p53-dependent Apoptosis Associated with Translocation of p53 to Mitochondria. J Biol Chem 2005; 280:19166-76. [PMID: 15753095 DOI: 10.1074/jbc.m410691200] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The tumor suppressor p53 functions as a transcriptional activator to induce cell cycle arrest and apoptosis in response to DNA damage. Although p53 was also shown to mediate apoptosis in a manner independent of its transactivation activity, the mechanism and conditions that trigger such cell death have remained largely unknown. We have now shown that inhibition of RNA polymerase II-mediated transcription by alpha-amanitin or RNA interference induced p53-dependent apoptosis. Inhibition of pol II-mediated transcription resulted in down-regulation of p21Cip1, which was caused by both transcriptional suppression and protein degradation, despite eliciting p53 accumulation, allowing the cells to progress into S phase and then to undergo apoptosis. This cell death did not require the transcription of p53 target genes and was preceded by translocation of the accumulated p53 to mitochondria. Our data thus suggested that blockade of pol II-mediated transcription induced p53 accumulation in mitochondria and was the critical factor for eliciting p53-dependent but transcription-independent apoptosis.
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Affiliation(s)
- Yoshimi Arima
- Department of Tumor Genetics and Biology, Graduate School of Medical Sciences, Kumamoto University, Honjo, Kumamoto 860-8556, Japan
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21
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Abstract
Cells induce the expression of DNA-repair enzymes, activate cell-cycle checkpoints and, under some circumstances, undergo apoptosis in response to DNA-damaging agents. The mechanisms by which these cellular responses are triggered are not well understood, but there is recent evidence that the transcription machinery might be used in DNA-damage surveillance and in triggering DNA-damage responses to suppress mutagenesis. Transcription might also act as a DNA-damage dosimeter where the severity of blockage determines whether or not to induce cell death. Could transcription therefore be a potential therapeutic target for anticancer strategies?
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Affiliation(s)
- Mats Ljungman
- Department of Radiation Oncology, Division of Radiation and Cancer Biology, University of Michigan Comprehensive Cancer Center, University of Michigan Medical School, University of Michigan, Ann Arbor, Michigan 48109-0936, USA.
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22
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Fiucci G, Beaucourt S, Duflaut D, Lespagnol A, Stumptner-Cuvelette P, Géant A, Buchwalter G, Tuynder M, Susini L, Lassalle JM, Wasylyk C, Wasylyk B, Oren M, Amson R, Telerman A. Siah-1b is a direct transcriptional target of p53: identification of the functional p53 responsive element in the siah-1b promoter. Proc Natl Acad Sci U S A 2004; 101:3510-5. [PMID: 14985507 PMCID: PMC373493 DOI: 10.1073/pnas.0400177101] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2003] [Indexed: 12/31/2022] Open
Abstract
Siah proteins are E3 ubiquitin ligases. They are homologues of the Drosophila seven in absentia (Sina), a protein required for the R7 photoreceptor development. We have previously found that the expression of human siah-1 and its mouse homologue siah-1b are induced by p53 during apoptosis and tumor reversion. So far, no evidence that the siah-1b gene is a direct transcriptional target of p53 has been provided. In the present study we investigate this issue. Northern blot analysis with a specific probe demonstrates an increase in siah-1b transcription on activation of endogenous and inducible exogenous p53. To explore whether this effect is directly mediated by p53 we analyzed 20 kb of chromosome X DNA, containing the siah-1b locus. A p53-binding site was identified in the siah-1b promoter, located at nucleotides -2155/-2103 relative to the translational start site. This site is composed of two half-sites, conforming to the p53-binding consensus sequence but separated by a nonclassical 33-bp spacer. In luciferase assays, p53 induces a substantial increase in siah-1b promoter activity. Gel shift and DNase-I-footprinting studies, combined with mutational analysis and chromatin immunoprecipitation, indicate that p53 effectively binds the siah-1b promoter in vitro and in vivo. Thus, the siah-1b gene is a direct transcriptional target of p53.
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Affiliation(s)
- Giusy Fiucci
- Molecular Engines Laboratories, 20 Rue Bouvier, 75011 Paris, France
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23
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Abstract
The p53 tumor suppressor can induce growth arrest, apoptosis and cell senescence. Not surprisingly, p53 is an appealing target for therapeutic intervention. Although current anticancer agents do not directly interact with p53, these agents (including DNA damaging drugs, antimetabolites, microtubule-active drugs and inhibitors of the proteasome) cause accumulation of wt p53. Depending on the p53 status of cancer cells, diverse therapeutic strategies are under development. These include pharmacological rescue of mutant p53 function and reactivation of wt p53 in E6-expressing cells. For protection of normal cells, strategies range from abrogation of wt p53 induction, thereby decreasing the toxicity of DNA damaging agents, to activation of wt p53-dependent checkpoints, thereby protecting cells against cell cycle-dependent therapeutics.
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24
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Okorokov AL, Rubbi CP, Metcalfe S, Milner J. The interaction of p53 with the nuclear matrix is mediated by F-actin and modulated by DNA damage. Oncogene 2002; 21:356-67. [PMID: 11821948 DOI: 10.1038/sj.onc.1205112] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2001] [Revised: 10/12/2001] [Accepted: 10/30/2001] [Indexed: 11/09/2022]
Abstract
The tumour suppressor protein p53 is localized in the cell nucleus where it serves to initiate cellular responses to a variety of stresses, particularly DNA damage and has the capacity to transactivate stress response genes. An emerging body of evidence indicates that its action is also exerted through direct protein-protein interactions. An approach to understanding p53 function has been to analyse its positioning in relation to nuclear structures and we have shown that p53 can associate with the nuclear matrix. A potential nuclear matrix component for this association is actin. Here we show that p53 interacts with nuclear F-actin and we map the domains involved in this interaction. Using fluorescence resonance energy transfer, we demonstrate that the partition of p53 between F-actin bound and unbound forms is not constant, but is modulated by the presence of DNA damage, which increases binding. Our results indicate that the dynamic interaction of p53 with the nuclear matrix has to be considered for a full understanding of the mechanisms of the p53-mediated cellular response to DNA damage.
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Affiliation(s)
- Andrei L Okorokov
- YCR P53 Research Group, Department of Biology, University of York, York, YO10 5DD, UK
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25
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Lee SK, Yu SL, Prakash L, Prakash S. Requirement for yeast RAD26, a homolog of the human CSB gene, in elongation by RNA polymerase II. Mol Cell Biol 2001; 21:8651-6. [PMID: 11713297 PMCID: PMC100025 DOI: 10.1128/mcb.21.24.8651-8656.2001] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2001] [Accepted: 09/19/2001] [Indexed: 11/20/2022] Open
Abstract
Mutations in the human CSB gene cause Cockayne syndrome (CS). In addition to increased photosensitivity, CS patients suffer from severe developmental abnormalities, including growth retardation and mental retardation. Whereas a deficiency in the preferential repair of UV lesions from the transcribed strand accounts for the increased photosensitivity of CS patients, the reason for developmental defects in these individuals has remained unclear. Here we provide in vivo evidence for a role of RAD26, the counterpart of the CSB gene in Saccharomyces cerevisiae, in transcription elongation by RNA polymerase II, and in addition we show that under conditions requiring rapid synthesis of new mRNAs, growth is considerably reduced in cells lacking RAD26. These findings implicate a role for CSB in transcription elongation, and they strongly suggest that impaired transcription elongation is the underlying cause of the developmental problems in CS patients.
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Affiliation(s)
- S K Lee
- Sealy Center for Molecular Science, University of Texas Medical Branch, 6.104 Blocker Medical Research Building, 11th and Mechanic Streets, Galveston, TX 77555-1061, USA
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26
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McKay BC, Becerril C, Ljungman M. P53 plays a protective role against UV- and cisplatin-induced apoptosis in transcription-coupled repair proficient fibroblasts. Oncogene 2001; 20:6805-8. [PMID: 11709715 DOI: 10.1038/sj.onc.1204901] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2001] [Revised: 07/27/2001] [Accepted: 08/07/2001] [Indexed: 11/09/2022]
Abstract
We previously reported that transcription-coupled repair (TCR)-deficient human fibroblasts are extremely sensitive to UV-induced apoptosis and this sensitivity correlated with the induction of the p53 tumour suppressor. However, we have also found that p53 can be protective against UV-induced apoptosis. Thus, prior to this study, it was not clear whether the induction of p53 in TCR-deficient fibroblasts contributed to their death. To address this issue, we have expressed human papillomavirus E6 (HPV-E6) in primary fibroblasts derived from patients affected with xeroderma pigmentosum (complementation groups A, B and C) and Cockayne syndrome (complementation group B). We found that TCR-deficient (XP-A, XP-B and CS-B) fibroblasts were more sensitive than TCR-proficient cells (XP-C and normal) to both UV light and cisplatin treatment and this increase in sensitivity was not p53 dependent. Importantly, HPV-E6 expression increased the sensitivity of TCR-proficient normal and XP-C fibroblasts to UV- and cisplatin-induced apoptosis. This increase in sensitivity correlated with a decrease in the capacity of HPV-E6 expressing cells to recover mRNA synthesis following UV-irradiation. Therefore, we propose that p53 protects against UV- and cisplatin-induced apoptosis in a TCR-dependent manner and that p53 does not contribute strongly to the induction of apoptosis in TCR-deficient fibroblasts.
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Affiliation(s)
- B C McKay
- Centre for Cancer Therapeutics, Ottawa Regional Cancer Centre, 503 Smyth Road, Ottawa, Ontario K1H 1C4, Canada
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27
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Scott M, Bonnefin P, Vieyra D, Boisvert FM, Young D, Bazett-Jones DP, Riabowol K. UV-induced binding of ING1 to PCNA regulates the induction of apoptosis. J Cell Sci 2001; 114:3455-62. [PMID: 11682605 DOI: 10.1242/jcs.114.19.3455] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous studies have shown that UV-induced binding of p21WAF1 to PCNA through the PCNA-interacting protein (PIP) domain in p21WAF1 promotes a switch from DNA replication to DNA repair by altering the PCNA protein complex. Here we show that the p33ING1b isoform of the ING1 candidate tumour suppressor contains a PIP domain. UV rapidly induces p33ING1b to bind PCNA competitively through this domain, a motif also found in DNA ligase, the DNA repair-associated FEN1 and XPG exo/endonucleases, and DNA methyltransferase. Interaction of p33ING1b with PCNA occurs between a significant proportion of ING1 and PCNA, increases more than tenfold in response to UV and is specifically inhibited by overexpression of p21WAF1, but not by p16MTS1, which has no PIP sequence. In contrast to wild-type p33ING1b, ING1 PIP mutants that do not bind PCNA do not induce apoptosis, but protect cells from UV-induced apoptosis, suggesting a role for this PCNA-p33ING1b interaction in eliminating UV-damaged cells through programmed cell death. These data indicate that ING1 competitively binds PCNA through a site used by growth regulatory and DNA damage proteins, and may contribute to regulating the switch from DNA replication to DNA repair by altering the composition of the PCNA protein complex.
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Affiliation(s)
- M Scott
- Department of Biochemistry, Faculty of Medicine, The University of Calgary, 3330 Hospital Drive, NW, Calgary, Alberta T2N 4N1, Canada
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28
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Lu W, Chen L, Peng Y, Chen J. Activation of p53 by roscovitine-mediated suppression of MDM2 expression. Oncogene 2001; 20:3206-16. [PMID: 11423970 DOI: 10.1038/sj.onc.1204412] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2000] [Revised: 01/14/2001] [Accepted: 02/21/2001] [Indexed: 11/09/2022]
Abstract
The p53 tumor suppressor is regulated by the MDM2 oncoprotein. Overexpression of MDM2 maintains p53 at low levels and contributes to the functional inactivation of p53 in a subset of tumors. We found that treatment with roscovitine and olomoucin, which were originally developed as cyclin-dependent kinase (CDK) inhibitors, can efficiently stabilize and activate nuclear p53 in tumor cells with MDM2 amplification or cytoplasmic p53. These inhibitors block the degradation of p53 without affecting p53-MDM2 binding and the nuclear shuttling function of p53 and MDM2. Roscovitine also induces stabilization of the p53 Ala-315 mutant, indicating that it does not act by regulating the CDK phosphorylation of serine 315. Roscovitine induces down-regulation of MDM2 expression at both protein and mRNA levels. Ectopic expression of MDM2 can abrogate the ability of roscovitine to induce p53 stabilization. Low concentrations of roscovitine cooperate with the DNA-damaging agent camptothecin to activate p53 in a synergistic fashion. These results show that the small molecule CDK inhibitors can be used to activate p53 through their potent inhibitory effect on MDM2 expression and may be useful as sensitizing agents for other DNA-damaging drugs.
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Affiliation(s)
- W Lu
- Molecular Oncology Program, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, Florida, FL 33612, USA
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29
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Seluanov A, Gorbunova V, Falcovitz A, Sigal A, Milyavsky M, Zurer I, Shohat G, Goldfinger N, Rotter V. Change of the death pathway in senescent human fibroblasts in response to DNA damage is caused by an inability to stabilize p53. Mol Cell Biol 2001; 21:1552-64. [PMID: 11238892 PMCID: PMC86701 DOI: 10.1128/mcb.21.5.1552-1564.2001] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cellular function of p53 is complex. It is well known that p53 plays a key role in cellular response to DNA damage. Moreover, p53 was implicated in cellular senescence, and it was demonstrated that p53 undergoes modification in senescent cells. However, it is not known how these modifications affect the ability of senescent cells to respond to DNA damage. To address this question, we studied the responses of cultured young and old normal diploid human fibroblasts to a variety of genotoxic stresses. Young fibroblasts were able to undergo p53-dependent and p53-independent apoptosis. In contrast, senescent fibroblasts were unable to undergo p53-dependent apoptosis, whereas p53-independent apoptosis was only slightly reduced. Interestingly, instead of undergoing p53-dependent apoptosis, senescent fibroblasts underwent necrosis. Furthermore, we found that old cells were unable to stabilize p53 in response to DNA damage. Exogenous expression or stabilization of p53 with proteasome inhibitors in old fibroblasts restored their ability to undergo apoptosis. Our results suggest that stabilization of p53 in response to DNA damage is impaired in old fibroblasts, resulting in induction of necrosis. The role of this phenomenon in normal aging and anticancer therapy is discussed.
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Affiliation(s)
- A Seluanov
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, 76100, Israel.
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30
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Blaydes JP, Craig AL, Wallace M, Ball HM, Traynor NJ, Gibbs NK, Hupp TR. Synergistic activation of p53-dependent transcription by two cooperating damage recognition pathways. Oncogene 2000; 19:3829-39. [PMID: 10951576 DOI: 10.1038/sj.onc.1203773] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
High level activation of p53-dependent transcription occurs following cellular exposure to genotoxic damaging agents such as UV-C, while ionizing radiation damage does not induce a similarly potent induction of p53-dependent gene expression. Reasoning that one of the major differences between UV-C and ionizing radiation damage is that the latter does not inhibit general transcription, we attempted to reconstitute p53-dependent gene expression in ionizing irradiated cells by co-treatment with selected transcription inhibitors that alone do not activate p53. p53-dependent transcription can be dramatically enhanced by the treatment of ionizing irradiated cells with low doses of DRB, which on its own does not induce p53 activity. The mechanism of ionizing radiation-dependent activation of p53-dependent transcription using DRB is more likely due to inhibition of gene transcription rather than prolonged DNA damage, as the non-genotoxic and general transcription inhibitor Roscovitine also synergistically activates p53 function in ionizing irradiated cells. These results identify two distinct signal transduction pathways that cooperate to fully activate p53-dependent gene expression: one responding to lesions induced by ionizing radiation and the second being a kinase pathway that regulates general RNA Polymerase II activity.
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Affiliation(s)
- J P Blaydes
- Department of Molecular and Cellular Pathology, Dundee Cancer Research Centre, Ninewells Medical School, University of Dundee, Scotland
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31
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Balajee AS, Proietti De Santis L, Brosh RM, Selzer R, Bohr VA. Role of the ATPase domain of the Cockayne syndrome group B protein in UV induced apoptosis. Oncogene 2000; 19:477-89. [PMID: 10698517 DOI: 10.1038/sj.onc.1203372] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cockayne syndrome (CS) is a human autosomal recessive disorder characterized by many neurological and developmental abnormalities. CS cells are defective in the transcription coupled repair (TCR) pathway that removes DNA damage from the transcribed strand of active genes. The individuals suffering from CS do not generally develop cancer but show increased neurodegeneration. Two genetic complementation groups (CS-A and CS-B) have been identified. The lack of cancer formation in CS may be due to selective elimination of cells containing DNA damage by a suicidal pathway. In this study, we have evaluated the role of the CSB gene in UV induced apoptosis in human and hamster cells. The hamster cell line UV61 carries a mutation in the homolog of the human CSB gene. We show that both human CS-B and hamster UV61 cells display increased apoptotic response following UV exposure compared with normal cells. The increased sensitivity of UV61 cells to apoptosis is complemented by the transfection of the wild type human CSB gene. In order to determine which functional domain of the CSB gene participates in the apoptotic pathway, we constructed stable cell lines with different CSB domain disruptions. UV61 cells were stably transfected with the human CSB cDNA containing a point mutation in the highly conserved glutamic acid residue in ATPase motif II. This cell line (UV61/ pc3.1-CSBE646Q) showed the same increased apoptosis as the UV61 cells. In contrast, cells containing a deletion in the acidic domain at the N-terminal end of the CSB protein had no effect on apoptosis. This indicates that the integrity of the ATPase domain of CSB protein is critical for preventing the UV induced apoptotic pathway. In primary human CS-B cells, the induction and stabilization of the p53 protein seems to correlate with their increased apoptotic potential. In contrast, no change in the level of either p53 or activation of mdm2 protein by p53 was observed in hamster UV61 cells after UV exposure. This suggests that the CSB dependent apoptotic pathway can occur independently of the transactivation potential of p53 in hamster cells.
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Affiliation(s)
- A S Balajee
- Laboratory of Molecular Genetics, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, USA
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32
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Rubbi CP, Milner J. Non-activated p53 co-localizes with sites of transcription within both the nucleoplasm and the nucleolus. Oncogene 2000; 19:85-96. [PMID: 10644983 DOI: 10.1038/sj.onc.1203378] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The p53 tumour suppressor functions as a sensor of genotoxic stress and, once activated, induces cell growth arrest or apoptosis. The precise intranuclear localization of latent p53 protein in non-stressed cells is unknown. Such information is essential in order to understand how relatively few molecules of p53 can detect and respond to DNA damage. Here we present the first detailed supramolecular localization of p53 in the nuclei of cells under normal conditions of growth. We show that soluble, non-bound p53 is released by permeabilization, leaving structurally bound p53 in both the nucleus and nucleolus. In situ biochemical studies reveal (i) that nuclear-bound p53 is tethered by RNA (directly or indirectly) and (ii) that a sub-population of nuclear-bound p53 co-localizes with sites of RNA synthesis. Transcriptional co-localization appeared to be independent of p53 conformation but dependent upon its quaternary structure. In the nucleolus p53 was observed at sites of rRNA synthesis and also adjacent to such sites. In contrast, nucleolar hdm-2 (shown by others to complex p53 and 5S RNA) was excluded from sites of rRNA synthesis. Our discovery that p53 is physically linked with sites of transcription may explain how relatively few p53 protein molecules can monitor genetic stress and respond preferentially to damage of actively transcribed genes.
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Affiliation(s)
- C P Rubbi
- YCR p53 Research Group, Biology Department, University of York, York YO1 5DD, UK
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te Poele RH, Okorokov AL, Joel SP. RNA synthesis block by 5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) triggers p53-dependent apoptosis in human colon carcinoma cells. Oncogene 1999; 18:5765-72. [PMID: 10523857 DOI: 10.1038/sj.onc.1202961] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Most modern chemo- and radiotherapy treatments of human cancers use the DNA damage pathway, which induces a p53 response leading to either G1 arrest or apoptosis. However, such treatments can induce mutations and translocations leading to secondary malignancies or recurrent disease, which often have a poor prognosis because of resistance to therapy. Here we report that 5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB), an inhibitor of CDK7 TFIIH-associated kinase, CKI and CKII kinases, blocking RNA polymerase II in the early elongation stage, triggers p53-dependent apoptosis in human colon adenocarcinoma cells in a transcription independent manner. The fact that DRB kills tumour-derived cells without employment of DNA damage gives rise to the possibility of the development of a new alternative chemotherapeutic treatment of tumours expressing wild type p53, with a decreased risk of therapy-related, secondary malignancies.
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Affiliation(s)
- R H te Poele
- Barry Reed Oncology Laboratory, ICRF Department of Medical Oncology, St Bartholomew's Hospital, West Smithfield, London EC1A 7BE, UK
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Wasylyk C, Salvi R, Argentini M, Dureuil C, Delumeau I, Abecassis J, Debussche L, Wasylyk B. p53 mediated death of cells overexpressing MDM2 by an inhibitor of MDM2 interaction with p53. Oncogene 1999; 18:1921-34. [PMID: 10208414 DOI: 10.1038/sj.onc.1202528] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The p53 tumour suppressor is frequently inactivated in human tumours. One form of inactivation results from overexpression of MDM2, that normally forms a negative auto-regulatory loop with p53 and inhibits its activity through complex formation. We have investigated whether disrupting the MDM2-p53 complex in cells that overexpress MDM2 is sufficient to trigger p53 mediated cell death. We find that expression of a peptide homologue of p53 that binds to MDM2 leads to increased p53 levels and transcriptional activity. The consequences are increased expression of the downstream effectors MDM2 and p21WAF1/CIP1, inhibition of colony formation, cell cycle arrest and cell death. There is also a decrease in E2F activity, that might have been due to the known physical and functional interactions of MDM2 with E2F1/DP1. However, this decrease is p53 dependent, as are also colony formation, cell cycle arrest and cell death. These results show that a peptide homologue of p53 is sufficient to induce p53 dependent cell death in cells overexpressing MDM2, and support the notion that disruption of the p53-MDM2 complex is a target for the development of therapeutic agents.
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Affiliation(s)
- C Wasylyk
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, Illkirch, France
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Ljungman M, Zhang F, Chen F, Rainbow AJ, McKay BC. Inhibition of RNA polymerase II as a trigger for the p53 response. Oncogene 1999; 18:583-92. [PMID: 9989808 DOI: 10.1038/sj.onc.1202356] [Citation(s) in RCA: 214] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The mechanisms by which the p53 response is triggered following exposure to DNA-damaging agents have not yet been clearly elucidated. We and others have previously suggested that blockage of RNA polymerase II may be the trigger for induction of the p53 response following exposure to ultraviolet light. Here we report on the correlation between inhibition of mRNA synthesis and the induction of p53, p21WAF1 and apoptosis in diploid human fibroblasts treated with either UV light, cisplatin or the RNA synthesis inhibitors actinomycin D, DRB, H7 and alpha-amanitin. Exposure to ionizing radiation or the proteasome inhibitor LLnL, however, induced p53 and p21WAF1 without affecting mRNA synthesis. Importantly, induction of p53 by the RNA synthesis or proteasome inhibitors did not correlate with the induction of DNA strand breaks. Furthermore, cisplatin-induced accumulation of active p53 in repair-deficient XP-A cells occurred despite the lack of DNA strand break induction. Our results suggest that the induction of the p53 response by certain toxic agents is not triggered by DNA strand breaks but rather, may be linked to inhibition of mRNA synthesis either directly by the poisoning of RNA polymerase II or indirectly by the induction of elongation-blocking DNA lesions.
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Affiliation(s)
- M Ljungman
- Department of Radiation Oncology, University of Michigan Comprehensive Cancer Center, Ann Arbor 48109-0936, USA
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