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Abstract
The model organism Saccharomyces cerevisiae is providing new insights into the molecular and cellular changes that are related to aging. The yeast protein Sir2p (Silent Information Regulator 2) is a histone deacetylase involved in transcriptional silencing and the control of genomic stability. Recent results have led to the identification of Sir2p as a crucial determinant of yeast life span. Dosage, intracellular localization, and activity of Sir2p all have important effects on yeast longevity. For instance, calorie restriction apparently increases yeast life span by increasing Sir2p activity. Since Sir2p-related proteins have been identified in many prokaryotic and eukaryotic organisms, the fundamental principles derived from the studies in yeast may prove valuable in directing our future research toward an understanding of the mechanisms of aging in higher eukaryotes. BioEssays 23:327-332, 2001.
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Affiliation(s)
- P A Defossez
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
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2
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Defossez PA. Sir2 : une déacétylase qui régule le vieillissement. Med Sci (Paris) 2001. [DOI: 10.4267/10608/2002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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3
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Abstract
Calorie restriction extends life-span in a wide variety of organisms. Although it has been suggested that calorie restriction may work by reducing the levels of reactive oxygen species produced during respiration, the mechanism by which this regimen slows aging is uncertain. Here, we mimicked calorie restriction in yeast by physiological or genetic means and showed a substantial extension in life-span. This extension was not observed in strains mutant for SIR2 (which encodes the silencing protein Sir2p) or NPT1 (a gene in a pathway in the synthesis of NAD, the oxidized form of nicotinamide adenine dinucleotide). These findings suggest that the increased longevity induced by calorie restriction requires the activation of Sir2p by NAD.
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Affiliation(s)
- S J Lin
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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4
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Park PU, Defossez PA, Guarente L. Effects of mutations in DNA repair genes on formation of ribosomal DNA circles and life span in Saccharomyces cerevisiae. Mol Cell Biol 1999; 19:3848-56. [PMID: 10207108 PMCID: PMC84236 DOI: 10.1128/mcb.19.5.3848] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/1998] [Accepted: 02/24/1999] [Indexed: 11/20/2022] Open
Abstract
A cause of aging in Saccharomyces cerevisiae is the accumulation of extrachromosomal ribosomal DNA circles (ERCs). Introduction of an ERC into young mother cells shortens life span and accelerates the onset of age-associated sterility. It is important to understand the process by which ERCs are generated. Here, we demonstrate that homologous recombination is necessary for ERC formation. rad52 mutant cells, defective in DNA repair through homologous recombination, do not accumulate ERCs with age, and mutations in other genes of the RAD52 class have varying effects on ERC formation. rad52 mutation leads to a progressive delocalization of Sir3p from telomeres to other nuclear sites with age and, surprisingly, shortens life span. We speculate that spontaneous DNA damage, perhaps double-strand breaks, causes lethality in mutants of the RAD52 class and may be an initial step of aging in wild-type cells.
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Affiliation(s)
- P U Park
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Defossez PA, Prusty R, Kaeberlein M, Lin SJ, Ferrigno P, Silver PA, Keil RL, Guarente L. Elimination of replication block protein Fob1 extends the life span of yeast mother cells. Mol Cell 1999; 3:447-55. [PMID: 10230397 DOI: 10.1016/s1097-2765(00)80472-4] [Citation(s) in RCA: 307] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A cause of aging in yeast is the accumulation of circular species of ribosomal DNA (rDNA) arising from the 100-200 tandemly repeated copies in the genome. We show here that mutation of the FOB1 gene slows the generation of these circles and thus extends life span. Fob1p is known to create a unidirectional block to replication forks in the rDNA. We show that Fob1p is a nucleolar protein, suggesting a direct involvement in the replication fork block. We propose that this block can trigger aging by causing chromosomal breaks, the repair of which results in the generation of rDNA circles. These findings may provide a novel link between metabolic rate and aging in yeast and, perhaps, higher organisms.
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Affiliation(s)
- P A Defossez
- Department of Biology Massachusetts Institute of Technology, Cambridge, 02139, USA
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Defossez PA. La recherche sur la sénescence est encore jeune. Med Sci (Paris) 1999. [DOI: 10.4267/10608/1292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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7
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Abstract
The past year has confirmed the great potential of the yeast Saccharomyces cerevisiae as a model to study aging. Ground breaking papers have revealed similarities between aging in yeast and in mammals, and have identified genetic instability of the ribosomal DNA array as the first known cause of aging in yeast cells.
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Affiliation(s)
- P A Defossez
- Department of Biology, Massachussetts Institute of Technology, 77 Massachussetts Avenue, Cambridge, MA 02139, USA.
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Defossez PA, Baert JL, Monnot M, de Launoit Y. The ETS family member ERM contains an alpha-helical acidic activation domain that contacts TAFII60. Nucleic Acids Res 1997; 25:4455-63. [PMID: 9358152 PMCID: PMC147095 DOI: 10.1093/nar/25.22.4455] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Transcription factors are modular entities built up of discrete domains, some devoted to DNA binding and others permitting transcriptional modulation. The structure of DNA binding domains has been thoroughly investigated and structural classes clearly defined. In sharp contrast, the structural constraints put on transactivating regions, if any, are mostly unknown. Our investigations focus on ERM, a eukaryotic transcription factor of the ETS family. We have previously shown that ERM harbours two transactivating domains (TADs) with distinct functional features: AD1 lies in the first 72 amino acids of ERM, while AD2 sits in the last 62. Here we show that AD1 is a bona fide acidic TAD, for it activated transcription in yeast cells, while AD2 did not. AD1 contains a 20 amino acid stretch predicted to form an alpha-helix that is found unchanged in the related PEA3 and ER81 transcription factors. Circular dichroism analysis revealed that a 32 amino acid peptide encompassing this region is unstructured in water but folds into a helix when the hydrophobic solvent trifluoroethanol is added. The isolated helix was sufficient to activate transcription and mutations predicted to disrupt it dramatically affected AD1-driven transactivation, whereas mutations decreasing its acidity had more gentle effects. A phenylalanine residue within the helix was particularly sensitive to mutations. Finally, we observed that ERM bound TAFII60 via AD1 and bound TBP and TAFII40, presumably via other activation domains.
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Affiliation(s)
- P A Defossez
- Mécanismes du Développement et de la Cancérisation, UMR 319 CNRS/Institut Pasteur de Lille, Institut de Biologie de Lille, 1 rue Calmette, BP 447, 59021 Lille Cedex, France
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Chotteau-Lelièvre A, Desbiens X, Pelczar H, Defossez PA, de Launoit Y. Differential expression patterns of the PEA3 group transcription factors through murine embryonic development. Oncogene 1997; 15:937-52. [PMID: 9285689 DOI: 10.1038/sj.onc.1201261] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
ERM, ER81 and PEA3 are three highly related transcription factors belonging to the ETS family. Together they form the PEA3 group within this family. Little data is yet available regarding the roles of these three genes during embryonic development. A prerequisite to investigations in this field is to obtain an accurate spatio-temporal expression map for the erm, er81 and pea3 genes. To this end, we have used in situ hybridization to compare their expression patterns during critical stages of murine embryogenesis. We report that all three genes are expressed in numerous developing organs coming from different embryonic tissues. The three genes appeared co-expressed in different organs but presented specific sites of expression, so that the resultant expression pattern could in fact reveal several distinct functions depending upon isolated and/or various combinations of the PEA3 member expression. These results suggest that erm, er81 and pea3 genes are differentially regulated, probably to serve important functions as cell proliferation control, tissue interaction mediator or cell differentiation, all over successive steps of the mouse organogenesis.
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Affiliation(s)
- A Chotteau-Lelièvre
- Mécanismes du Développement et de la Cancérisation, UMR 319 CNRS/Institut Pasteur de Lille-Institut de Biologie de Lille, France
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de Launoit Y, Baert JL, Chotteau A, Monte D, Defossez PA, Coutte L, Pelczar H, Leenders F. Structure-function relationships of the PEA3 group of Ets-related transcription factors. Biochem Mol Med 1997; 61:127-35. [PMID: 9259977 DOI: 10.1006/bmme.1997.2605] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The PEA3 group of transcription factors belongs to the Ets family and is composed of PEA3, ERM, and ER81, which are more than 95% identical within the DNA-binding domain--the ETS domain--and which demonstrate 50% aa identity overall. We present here a review of the current knowledge of these transcription factors, which possess functional domains responsible for DNA-binding, DNA-binding inhibition, and transactivation. Recent data suggest that these factors are targets for signaling cascades, such as the Ras-dependent ones, and thus may contribute first to the nuclear response to cell stimulation and second to Ras-induced cell transformation. The expression of the PEA3 group members in numerous developing murine organs, and, especially, in epithelial-mesenchymal interaction events, suggests a key role in murine organogenesis. Moreover, their expression in certain breast cancer cells suggests a possible involvement of these genes in the appearance, progression, and invasion of malignant cells.
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Affiliation(s)
- Y de Launoit
- UMR 319 CNRS, Institut Pasteur de Lille, France.
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Schneikert J, Peterziel H, Defossez PA, Klocker H, de Launoit Y, Cato AC. Androgen receptor-Ets protein interaction is a novel mechanism for steroid hormone-mediated down-modulation of matrix metalloproteinase expression. J Biol Chem 1996; 271:23907-13. [PMID: 8798622 DOI: 10.1074/jbc.271.39.23907] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Matrix metalloproteinases belong to a family of structurally related enzymes that plays important role in tissue morphogenesis, differentiation, and wound healing. Their expression is negatively regulated by several members of the steroid hormone receptor family. This is thought to occur through interaction of the steroid receptors with the transcription factor AP-1 that is otherwise required for positive regulation. Here, we demonstrate that AP-1 is not always a target for down-regulation of expression of matrix metalloproteinases by steroid receptors. Androgen receptor negatively regulates matrix metalloproteinase-1 expression not through AP-1 but through a family of Ets-related transcription factors that are also required for positive regulation. This negative regulation is specific for the androgen receptor. It does not require the DNA binding activity but needs amino-terminal sequences of the receptor. These results identify a novel regulatory pathway for negative regulation utilized by a member of the steroid hormone receptor family for down-regulating the expression of matrix metalloproteinases.
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Affiliation(s)
- J Schneikert
- Forschungszentrum Karlsruhe, Institute of Genetics, P.O. Box 3640, D-76021 Karlsruhe, Federal Republic of Germany
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Monté D, Coutte L, Dewitte F, Defossez PA, Le Coniat M, Stéhelin D, Berger R, de Launoit Y. Genomic organization of the human ERM (ETV5) gene, a PEA3 group member of ETS transcription factors. Genomics 1996; 35:236-40. [PMID: 8661127 DOI: 10.1006/geno.1996.0345] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The ERM protein belongs to the family of Ets transcription factors. We show here that the human ERM gene is organized into 14 exons distributed along 65 kb of genomic DNA on chromosome 3. The two main functional domains of ERM, the acidic domain and the DNA-binding ETS domain, are overlapped by three different exons each. The 3'-untranslated region of ERM is 2.1 kb, whereas the 5'-untranslated region is about 0.3 kb; this allows the transcription of ERM transcripts of approximately 4 kb. The human ERM gene is localized to the q27-q29 region of chromosome 3.
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Affiliation(s)
- D Monté
- Unité d'Oncologie Moléculaire, CNRS URA 1160-Institut Pasteur de Lille, Lille Cedex, 59019, France
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Laget MP, Defossez PA, Albagli O, Baert JL, Dewitte F, Stehelin D, de Launoit Y. Two functionally distinct domains responsible for transactivation by the Ets family member ERM. Oncogene 1996; 12:1325-36. [PMID: 8649835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The recently cloned human Ets transcription factor ERM is closely related to the ER81 and PEA3 genes. Here, we report the functional analysis of the DNA-binding and transactivation properties of ERM. Specific DNA-binding by ERM requires the ETS domain, conserved in all members of the Ets family and is inhibited by an 84 residue long central region and the carboxy-terminal tail. Two fragments of ERM are transferrable activation domains: alpha, which sits in the 72 first residues and encompasses the acidic domain conserved between ERM, ER81 and PEA3, and the carboxy-terminal tail which also bears a DNA-binding inhibition function. Deletion of alpha strongly reduces transactivation by ERM. Moreover, alpha and the carboxy-terminal tail exhibit functional synergism, suggesting that they activate transcription through different mechanisms. In support of this idea, we demonstrate that VP16 squelches transactivation by alpha but not by the carboxy-terminal tail. This result also indicates that alpha and VP16 may share common limiting cofactors. alpha and the carboxy-terminal tail do not seem to be conserved within the whole Ets family, indicating that the specificity of ERM may rely on interactions with distinct cofactors.
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Affiliation(s)
- M P Laget
- Unité d'Oncologie Moléculaire, Institut Pasteur, Lille, France
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Monté D, Baert JL, Defossez PA, de Launoit Y, Stéhelin D. Molecular cloning and characterization of human ERM, a new member of the Ets family closely related to mouse PEA3 and ER81 transcription factors. Oncogene 1994; 9:1397-406. [PMID: 8152800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The ets-related transcription factors PEA3 and ER81 have recently been isolated and characterized in the mouse. They share 95% identity in a 85 amino acid (AA) domain termed the ETS domain which is responsible for DNA binding, and therefore they form an Ets family group. By screening a human testis cDNA library with a probe containing the mouse PEA3 ETS domain, we isolated a 2.2 kb clone containing a 510 AA open reading frame. Since the ETS domain, which is localized in the carboxy terminal region of the encoded protein, is 95% and 96% identical to that of PEA3 and ER81, respectively, we named this new member 'Ets Related Molecule PEA3-like' (ERM). Although the first 120 AA in the amino-terminal region of ERM share 47% identity with PEA3 and 66% with ER81, ERM contains a central region of approximately 35 AA not found in the two mouse proteins. Gel shift analysis indicates that the full-length ERM protein is able to bind specifically to an oligonucleotide containing the consensus nucleotide core sequence GGAA recognized by the Ets proteins. Moreover, in vitro translation of 83 AA of the ERM ETS domain led to the production of a truncated protein which also binds to DNA. Though differential expression is observed in primary tumors and normal lymphocytes do not express ERM, this gene is almost ubiquitously expressed in human normal tissues. ERM mRNA is highly expressed in brain as well as in placenta and, to a lesser degree, in lung, pancreas, and heart. Moreover, almost all human cell lines tested express it at varying levels. In mouse tissues, we showed that PEA3 and ER81 mRNAs display restricted expression, whereas ERM is almost ubiquitously expressed as observed for human tissues. Altogether these results indicate that ERM is clearly a new ets family member and not the human equivalent of PEA3 or ER81.
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Affiliation(s)
- D Monté
- Unité d'Oncologie Molèculaire, CNRS URA 1160, Institut Pasteur de Lille, France
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