151
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Busch A, Kiel T, Heupel WM, Wehnert M, Hübner S. Nuclear protein import is reduced in cells expressing nuclear envelopathy-causing lamin A mutants. Exp Cell Res 2009; 315:2373-85. [PMID: 19442658 DOI: 10.1016/j.yexcr.2009.05.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Revised: 04/12/2009] [Accepted: 05/06/2009] [Indexed: 01/29/2023]
Abstract
Lamins, which form the nuclear lamina, not only constitute an important determinant of nuclear architecture, but additionally play essential roles in many nuclear functions. Mutations in A-type lamins cause a wide range of human genetic disorders (laminopathies). The importance of lamin A (LaA) in the spatial arrangement of nuclear pore complexes (NPCs) prompted us to study the role of LaA mutants in nuclear protein transport. Two mutants, causing prenatal skin disease restrictive dermopathy (RD) and the premature aging disease Hutchinson Gilford progeria syndrome, were used for expression in HeLa cells to investigate their impact on the subcellular localization of NPC-associated proteins and nuclear protein import. Furthermore, dynamics of the LaA mutants within the nuclear lamina were studied. We observed affected localization of NPC-associated proteins, diminished lamina dynamics for both LaA mutants and reduced nuclear import of representative cargo molecules. Intriguingly, both LaA mutants displayed similar effects on nuclear morphology and functions, despite their differences in disease severity. Reduced nuclear protein import was also seen in RD fibroblasts and impaired lamina dynamics for the nucleoporin Nup153. Our data thus represent the first study of a direct link between LaA mutant expression and reduced nuclear protein import.
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Affiliation(s)
- Albert Busch
- University of Würzburg, Institute of Anatomy and Cell Biology, Koellikerstrasse 6, 97070 Würzburg, Germany
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152
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Barrowman J, Michaelis S. ZMPSTE24, an integral membrane zinc metalloprotease with a connection to progeroid disorders. Biol Chem 2009; 390:761-73. [DOI: 10.1515/bc.2009.080] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
ZMPSTE24 is an integral membrane zinc metalloprotease originally discovered in yeast as an enzyme (called Ste24p) required for maturation of the mating pheromone a-factor. Surprisingly, ZMPSTE24 has recently emerged as a key protease involved in human progeroid disorders. ZMPSTE24 has only one identified mammalian substrate, the precursor of the nuclear scaffold protein lamin A. ZMPSTE24 performs a critical endoproteolytic cleavage step that removes the hydrophobic farnesyl-modified tail of prelamin A. Failure to do so has drastic consequences for human health and longevity. Here, we discuss the discovery of the yeast and mammalian ZMPSTE24 orthologs and review the unexpected connection between ZMPSTE24 and premature aging.
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153
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Webster M, Witkin KL, Cohen-Fix O. Sizing up the nucleus: nuclear shape, size and nuclear-envelope assembly. J Cell Sci 2009; 122:1477-86. [PMID: 19420234 DOI: 10.1242/jcs.037333] [Citation(s) in RCA: 279] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The nucleus is one of the most prominent cellular organelles, yet surprisingly little is known about how it is formed, what determines its shape and what defines its size. As the nuclear envelope (NE) disassembles in each and every cell cycle in metazoans, the process of rebuilding the nucleus is crucial for proper development and cell proliferation. In this Commentary, we summarize what is known about the regulation of nuclear shape and size, and highlight recent findings that shed light on the process of building a nucleus, including new discoveries related to NE assembly and the relationship between the NE and the endoplasmic reticulum (ER). Throughout our discussion, we note interesting aspects of nuclear structure that have yet to be resolved. Finally, we present an idea - which we refer to as ;the limited flat membrane hypothesis' - to explain the formation of a single nucleus that encompasses of all of the cell's chromosomes following mitosis.
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Affiliation(s)
- Micah Webster
- The Laboratory of Cellular and Molecular Biology, NIDDK, NIH, Bethesda, MD 20892, USA
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154
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Worman HJ, Fong LG, Muchir A, Young SG. Laminopathies and the long strange trip from basic cell biology to therapy. J Clin Invest 2009; 119:1825-36. [PMID: 19587457 PMCID: PMC2701866 DOI: 10.1172/jci37679] [Citation(s) in RCA: 198] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The main function of the nuclear lamina, an intermediate filament meshwork lying primarily beneath the inner nuclear membrane, is to provide structural scaffolding for the cell nucleus. However, the lamina also serves other functions, such as having a role in chromatin organization, connecting the nucleus to the cytoplasm, gene transcription, and mitosis. In somatic cells, the main protein constituents of the nuclear lamina are lamins A, C, B1, and B2. Interest in the nuclear lamins increased dramatically in recent years with the realization that mutations in LMNA, the gene encoding lamins A and C, cause a panoply of human diseases ("laminopathies"), including muscular dystrophy, cardiomyopathy, partial lipodystrophy, and progeroid syndromes. Here, we review the laminopathies and the long strange trip from basic cell biology to therapeutic approaches for these diseases.
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Affiliation(s)
- Howard J. Worman
- Department of Medicine and
Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, USA.
Department of Medicine and
Department of Human Genetics, UCLA David Geffen School of Medicine, Los Angeles, California, USA
| | - Loren G. Fong
- Department of Medicine and
Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, USA.
Department of Medicine and
Department of Human Genetics, UCLA David Geffen School of Medicine, Los Angeles, California, USA
| | - Antoine Muchir
- Department of Medicine and
Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, USA.
Department of Medicine and
Department of Human Genetics, UCLA David Geffen School of Medicine, Los Angeles, California, USA
| | - Stephen G. Young
- Department of Medicine and
Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, USA.
Department of Medicine and
Department of Human Genetics, UCLA David Geffen School of Medicine, Los Angeles, California, USA
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155
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Prokocimer M, Davidovich M, Nissim-Rafinia M, Wiesel-Motiuk N, Bar DZ, Barkan R, Meshorer E, Gruenbaum Y. Nuclear lamins: key regulators of nuclear structure and activities. J Cell Mol Med 2009; 13:1059-85. [PMID: 19210577 PMCID: PMC4496104 DOI: 10.1111/j.1582-4934.2008.00676.x] [Citation(s) in RCA: 205] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Accepted: 01/19/2009] [Indexed: 11/27/2022] Open
Abstract
The nuclear lamina is a proteinaceous structure located underneath the inner nuclear membrane (INM), where it associates with the peripheral chromatin. It contains lamins and lamin-associated proteins, including many integral proteins of the INM, chromatin modifying proteins, transcriptional repressors and structural proteins. A fraction of lamins is also present in the nucleoplasm, where it forms stable complexes and is associated with specific nucleoplasmic proteins. The lamins and their associated proteins are required for most nuclear activities, mitosis and for linking the nucleoplasm to all major cytoskeletal networks in the cytoplasm. Mutations in nuclear lamins and their associated proteins cause about 20 different diseases that are collectively called laminopathies'. This review concentrates mainly on lamins, their structure and their roles in DNA replication, chromatin organization, adult stem cell differentiation, aging, tumorogenesis and the lamin mutations leading to laminopathic diseases.
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Affiliation(s)
- Miron Prokocimer
- Department of Genetics, The Institute of Life Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Maya Davidovich
- Department of Genetics, The Institute of Life Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Malka Nissim-Rafinia
- Department of Genetics, The Institute of Life Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Naama Wiesel-Motiuk
- Department of Genetics, The Institute of Life Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Daniel Z Bar
- Department of Genetics, The Institute of Life Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Rachel Barkan
- Department of Genetics, The Institute of Life Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Eran Meshorer
- Department of Genetics, The Institute of Life Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Yosef Gruenbaum
- Department of Genetics, The Institute of Life Sciences, The Hebrew University of JerusalemJerusalem, Israel
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156
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From the rarest to the most common: insights from progeroid syndromes into skin cancer and aging. J Invest Dermatol 2009; 129:2340-50. [PMID: 19387478 DOI: 10.1038/jid.2009.103] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Despite their rarity, diseases of premature aging, or "progeroid" syndromes, have provided important insights into basic mechanisms that may underlie cancer and normal aging. In this review, we highlight these recent developments in Hutchinson-Gilford progeria syndrome (HGPS), Werner syndrome, Bloom syndrome, Cockayne syndrome, trichothiodystrophy, ataxia-telangiectasia, Rothmund-Thomson syndrome, and xeroderma pigmentosum. Though they are caused by different mutations in various genes and often result in quite disparate phenotypes, deciphering the molecular bases of these conditions has served to highlight their underlying basic similarities. Studies of progeroid syndromes, particularly HGPS, the most dramatic form of premature aging, have contributed to our knowledge of fundamental processes of importance to skin biology, including DNA transcription, replication, and repair, genome instability, cellular senescence, and stem-cell differentiation.
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157
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Coutinho HDM, Falcão-Silva VS, Gonçalves GF, da Nóbrega RB. Molecular ageing in progeroid syndromes: Hutchinson-Gilford progeria syndrome as a model. IMMUNITY & AGEING 2009; 6:4. [PMID: 19379495 PMCID: PMC2674425 DOI: 10.1186/1742-4933-6-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Accepted: 04/20/2009] [Indexed: 01/09/2023]
Abstract
Hutchinson-Gilford progeria syndrome (HGPS) is a rare premature aging disorder that belongs to a group of conditions called laminopathies which affect nuclear lamins. Mutations in two genes, LMNA and ZMPSTE24, have been found in patients with HGPS. The p.G608G LMNA mutation is the most commonly reported mutation. The aim of this work was to compile a comprehensive literature review of the clinical features and genetic mutations and mechanisms of this syndrome as a contribution to health care workers. This review shows the necessity of a more detailed clinical identification of Hutchinson-Gilford progeria syndrome and the need for more studies on the pharmacologic and pharmacogenomic approach to this syndrome.
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Affiliation(s)
- Henrique Douglas M Coutinho
- Laboratório de Pesquisa em Produtos Naturais, Departamento de Ciências físicas e Biológicas, Centro de Ciências Biológicas e da Saúde, Universidade Regional do Cariri, Crato (CE), Brazil.
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158
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Fong LG, Vickers TA, Farber EA, Choi C, Yun UJ, Hu Y, Yang SH, Coffinier C, Lee R, Yin L, Davies BSJ, Andres DA, Spielmann HP, Bennett CF, Young SG. Activating the synthesis of progerin, the mutant prelamin A in Hutchinson-Gilford progeria syndrome, with antisense oligonucleotides. Hum Mol Genet 2009; 18:2462-71. [PMID: 19376814 PMCID: PMC2694694 DOI: 10.1093/hmg/ddp184] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Hutchinson-Gilford progeria syndrome (HGPS) is caused by point mutations that increase utilization of an alternate splice donor site in exon 11 of LMNA (the gene encoding lamin C and prelamin A). The alternate splicing reduces transcripts for wild-type prelamin A and increases transcripts for a truncated prelamin A (progerin). Here, we show that antisense oligonucleotides (ASOs) against exon 11 sequences downstream from the exon 11 splice donor site promote alternate splicing in both wild-type and HGPS fibroblasts, increasing the synthesis of progerin. Indeed, wild-type fibroblasts transfected with these ASOs exhibit progerin levels similar to (or greater than) those in fibroblasts from HGPS patients. This progerin was farnesylated, as judged by metabolic labeling studies. The synthesis of progerin in wild-type fibroblasts was accompanied by the same nuclear shape and gene-expression perturbations observed in HGPS fibroblasts. An ASO corresponding to the 5' portion of intron 11 also promoted alternate splicing. In contrast, an ASO against exon 11 sequences 5' to the alternate splice site reduced alternate splicing in HGPS cells and modestly lowered progerin levels. Thus, different ASOs can be used to increase or decrease 'HGPS splicing'. ASOs represent a new and powerful tool for recreating HGPS pathophysiology in wild-type cells.
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Affiliation(s)
- Loren G Fong
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
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159
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Malhas AN, Lee CF, Vaux DJ. Lamin B1 controls oxidative stress responses via Oct-1. J Cell Biol 2009; 184:45-55. [PMID: 19139261 PMCID: PMC2615091 DOI: 10.1083/jcb.200804155] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Accepted: 12/11/2008] [Indexed: 12/14/2022] Open
Abstract
Interaction of lamins with chromatin and transcription factors regulate transcription. Oct-1 has previously been shown to colocalize partly with B-type lamins and is essential for transcriptional regulation of oxidative stress response genes. Using sequential extraction, co-immunoprecipitation (IP), fluorescence loss in photobleaching, and fluorescence resonance energy transfer, we confirm Oct-1-lamin B1 association at the nuclear periphery and show that this association is lost in Lmnb1(Delta/Delta) cells. We show that several Oct-1-dependent genes, including a subset involved in oxidative stress response, are dysregulated in Lmnb1(Delta/Delta) cells. Electrophoretic mobility shift assay and chromatin IP reveal that Oct-1 binds to the putative octamer-binding sequences of the dysregulated genes and that this activity is increased in cells lacking functional lamin B1. Like Oct1(-/-) cells, Lmnb1(Delta/Delta) cells have elevated levels of reactive oxygen species and are more susceptible to oxidative stress. Sequestration of Oct-1 at the nuclear periphery by lamin B1 may be a mechanism by which the nuclear envelope can regulate gene expression and contribute to the cellular response to stress, development, and aging.
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Affiliation(s)
- Ashraf N Malhas
- Department of Physics, Sir William Dunn School of Pathology, University of Oxford, Oxford, England, UK
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160
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Caution! Analyze transcripts from conditional knockout alleles. Transgenic Res 2008; 18:483-9. [PMID: 19093225 DOI: 10.1007/s11248-008-9237-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Accepted: 11/27/2008] [Indexed: 10/21/2022]
Abstract
A common strategy for conditional knockout alleles is to "flox" (flank with loxP sites) a 5' exon within the target gene. Typically, the floxed exon does not contain a unit number of codons so that the Cre-mediated recombination event yields a frameshift and a null allele. Documenting recombination within the genomic DNA is often regarded as sufficient proof of a frameshift, and the analysis of transcripts is neglected. We evaluated a previously reported conditional knockout allele for the beta-subunit of protein farnesyltransferase. The recombination event in that allele-the excision of exon 3-was predicted to yield a frameshift. However, following the excision of exon 3, exon 4 was skipped by the mRNA splicing machinery, and the predominant transcript from the mutant allele lacked exon 3 and exon 4 sequences. The "Deltaexon 3-4 transcript" does not contain a frameshift but rather is predicted to encode a protein with a short in-frame deletion. This represents a significant concern when studying an enzyme, since an enzyme with partial function could lead to erroneous conclusions. With thousands of new conditional knockout alleles under construction within mouse mutagenesis consortiums, the protein farnesyltransferase allele holds an important lesson-to characterize knockout alleles at both the DNA and RNA levels.
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161
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Ding SL, Shen CY. Model of human aging: recent findings on Werner's and Hutchinson-Gilford progeria syndromes. Clin Interv Aging 2008; 3:431-44. [PMID: 18982914 PMCID: PMC2682376 DOI: 10.2147/cia.s1957] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The molecular mechanisms involved in human aging are complicated. Two progeria syndromes, Werner's syndrome (WS) and Hutchinson-Gilford progeria syndrome (HGPS), characterized by clinical features mimicking physiological aging at an early age, provide insights into the mechanisms of natural aging. Based on recent findings on WS and HGPS, we suggest a model of human aging. Human aging can be triggered by two main mechanisms, telomere shortening and DNA damage. In telomere-dependent aging, telomere shortening and dysfunction may lead to DNA damage responses which induce cellular senescence. In DNA damage-initiated aging, DNA damage accumulates, along with DNA repair deficiencies, resulting in genomic instability and accelerated cellular senescence. In addition, aging due to both mechanisms (DNA damage and telomere shortening) is strongly dependent on p53 status. These two mechanisms can also act cooperatively to increase the overall level ofgenomic instability, triggering the onset of human aging phenotypes.
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Affiliation(s)
- Shian-Ling Ding
- Department of Nursing, Kang-Ning Junior College of Medical Care and Management,Taipei,Taiwan.
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162
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Yang SH, Andres DA, Spielmann HP, Young SG, Fong LG. Progerin elicits disease phenotypes of progeria in mice whether or not it is farnesylated. J Clin Invest 2008; 118:3291-300. [PMID: 18769635 DOI: 10.1172/jci35876] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Accepted: 07/16/2008] [Indexed: 01/04/2023] Open
Abstract
Hutchinson-Gilford progeria syndrome (HGPS), a rare disease that results in what appears to be premature aging, is caused by the production of a mutant form of prelamin A known as progerin. Progerin retains a farnesyl lipid anchor at its carboxyl terminus, a modification that is thought to be important in disease pathogenesis. Inhibition of protein farnesylation improves the hallmark nuclear shape abnormalities in HGPS cells and ameliorates disease phenotypes in mice harboring a knockin HGPS mutation (LmnaHG/+). The amelioration of disease, however, is incomplete, leading us to hypothesize that nonfarnesylated progerin also might be capable of eliciting disease. To test this hypothesis, we created knockin mice expressing nonfarnesylated progerin (LmnanHG/+). LmnanHG/+ mice developed the same disease phenotypes observed in LmnaHG/+ mice, although the phenotypes were milder, and mouse embryonic fibroblasts (MEFs) derived from these mice contained fewer misshapen nuclei. The steady-state levels of progerin in LmnanHG/+ MEFs and tissues were lower, suggesting a possible explanation for the milder phenotypes. These data support the concept that inhibition of protein farnesylation in progeria could be therapeutically useful but also suggest that this approach may be limited, as progerin elicits disease phenotypes whether or not it is farnesylated.
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Affiliation(s)
- Shao H Yang
- Department of Medicine, UCLA David Geffen School of Medicine, Los Angeles, California, USA
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163
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Osorio FG, Obaya ÁJ, López-Otín C, Freije JMP. Accelerated ageing: from mechanism to therapy through animal models. Transgenic Res 2008; 18:7-15. [DOI: 10.1007/s11248-008-9226-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Accepted: 10/27/2008] [Indexed: 11/28/2022]
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164
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Barrowman J, Hamblet C, George CM, Michaelis S. Analysis of prelamin A biogenesis reveals the nucleus to be a CaaX processing compartment. Mol Biol Cell 2008; 19:5398-408. [PMID: 18923140 DOI: 10.1091/mbc.e08-07-0704] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Proteins establish and maintain a distinct intracellular localization by means of targeting, retention, and retrieval signals, ensuring most proteins reside predominantly in one cellular location. The enzymes involved in the maturation of lamin A present a challenge to this paradigm. Lamin A is first synthesized as a 74-kDa precursor, prelamin A, with a C-terminal CaaX motif and undergoes a series of posttranslational modifications including CaaX processing (farnesylation, aaX cleavage and carboxylmethylation), followed by endoproteolytic cleavage by Zmpste24. Failure to cleave prelamin A results in progeria and related premature aging disorders. Evidence suggests prelamin A is imported directly into the nucleus where it is processed. Paradoxically, the processing enzymes have been shown to reside in the cytosol (farnesyltransferase), or are ER membrane proteins (Zmpste24, Rce1, and Icmt) with their active sites facing the cytosol. Here we have reexamined the cellular site of prelamin A processing, and show that the mammalian and yeast processing enzymes Zmpste24 and Icmt exhibit a dual localization to the inner nuclear membrane, as well as the ER membrane. Our findings reveal the nucleus to be a physiologically relevant location for CaaX processing, and provide insight into the biology of a protein at the center of devastating progeroid diseases.
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Affiliation(s)
- Jemima Barrowman
- Department of Cell Biology, The Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
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165
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Capell BC, Olive M, Erdos MR, Cao K, Faddah DA, Tavarez UL, Conneely KN, Qu X, San H, Ganesh SK, Chen X, Avallone H, Kolodgie FD, Virmani R, Nabel EG, Collins FS. A farnesyltransferase inhibitor prevents both the onset and late progression of cardiovascular disease in a progeria mouse model. Proc Natl Acad Sci U S A 2008; 105:15902-7. [PMID: 18838683 PMCID: PMC2562418 DOI: 10.1073/pnas.0807840105] [Citation(s) in RCA: 152] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Indexed: 01/15/2023] Open
Abstract
Hutchinson-Gilford progeria syndrome (HGPS) is the most dramatic form of human premature aging. Death occurs at a mean age of 13 years, usually from heart attack or stroke. Almost all cases of HGPS are caused by a de novo point mutation in the lamin A (LMNA) gene that results in production of a mutant lamin A protein termed progerin. This protein is permanently modified by a lipid farnesyl group, and acts as a dominant negative, disrupting nuclear structure. Treatment with farnesyltransferase inhibitors (FTIs) has been shown to prevent and even reverse this nuclear abnormality in cultured HGPS fibroblasts. We have previously created a mouse model of HGPS that shows progressive loss of vascular smooth muscle cells in the media of the large arteries, in a pattern that is strikingly similar to the cardiovascular disease seen in patients with HGPS. Here we show that the dose-dependent administration of the FTI tipifarnib (R115777, Zarnestra) to this HGPS mouse model can significantly prevent both the onset of the cardiovascular phenotype as well as the late progression of existing cardiovascular disease. These observations provide encouraging evidence for the current clinical trial of FTIs for this rare and devastating disease.
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Affiliation(s)
- Brian C. Capell
- *Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-8004
- New York University School of Medicine, New York, NY 10016
| | - Michelle Olive
- *Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-8004
| | - Michael R. Erdos
- *Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-8004
| | - Kan Cao
- *Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-8004
| | - Dina A. Faddah
- *Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-8004
| | - Urraca L. Tavarez
- *Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-8004
| | - Karen N. Conneely
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322
| | - Xuan Qu
- *Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-8004
| | - Hong San
- *Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-8004
| | - Santhi K. Ganesh
- *Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-8004
| | - Xiaoyan Chen
- *Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-8004
| | | | | | | | - Elizabeth G. Nabel
- *Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-8004
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Francis S. Collins
- *Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-8004
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166
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Kudlow BA, Stanfel MN, Burtner CR, Johnston ED, Kennedy BK. Suppression of proliferative defects associated with processing-defective lamin A mutants by hTERT or inactivation of p53. Mol Biol Cell 2008; 19:5238-48. [PMID: 18843043 DOI: 10.1091/mbc.e08-05-0492] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Hutchinson-Gilford progeria syndrome (HGPS) is a rare, debilitating disease with early mortality and rapid onset of aging-associated pathologies. It is linked to mutations in LMNA, which encodes A-type nuclear lamins. The most frequent HGPS-associated LMNA mutation results in a protein, termed progerin, with an internal 50 amino acid deletion and, unlike normal A-type lamins, stable farnesylation. The cellular consequences of progerin expression underlying the HGPS phenotype remain poorly understood. Here, we stably expressed lamin A mutants, including progerin, in otherwise identical primary human fibroblasts to compare the effects of different mutants on nuclear morphology and cell proliferation. We find that expression of progerin leads to inhibition of proliferation in a high percentage of cells and slightly premature senescence in the population. Expression of a stably farnesylated mutant of lamin A phenocopied the immediate proliferative defects but did not result in premature senescence. Either p53 inhibition or, more surprisingly, expression of the catalytic subunit of telomerase (hTERT) suppressed the early proliferative defects associated with progerin expression. These findings lead us to propose that progerin may interfere with telomere structure or metabolism in a manner suppressible by increased telomerase levels and possibly link mechanisms leading to progeroid phenotypes to those of cell immortalization.
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Affiliation(s)
- Brian A Kudlow
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
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167
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Davies BSJ, Yang SH, Farber E, Lee R, Buck SB, Andres DA, Spielmann HP, Agnew BJ, Tamanoi F, Fong LG, Young SG. Increasing the length of progerin's isoprenyl anchor does not worsen bone disease or survival in mice with Hutchinson-Gilford progeria syndrome. J Lipid Res 2008; 50:126-34. [PMID: 18757838 DOI: 10.1194/jlr.m800424-jlr200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hutchinson-Gilford progeria syndrome (HGPS) is caused by the synthesis of a truncated prelamin A, commonly called progerin, that contains a carboxyl-terminal farnesyl lipid anchor. The farnesyl lipid anchor helps to target progerin to membrane surfaces at the nuclear rim, where it disrupts the integrity of the nuclear lamina and causes misshapen nuclei. Several lines of evidence have suggested that progerin's farnesyl lipid anchor is crucial for the emergence of disease phenotypes. Because a geranylgeranyl lipid is approximately 45-fold more potent than a farnesyl lipid in anchoring proteins to lipid membranes, we hypothesized that a geranylgeranylated version of progerin might be more potent in eliciting disease phenotypes. To test this hypothesis, we used gene targeting to create mice expressing geranylgeranylated progerin (Lmna(ggHG/+)). We then compared Lmna(ggHG/+) mice, side-by-side, with otherwise identical mice expressing farnesylated progerin (Lmna(HG/+)). Geranylgeranylation of progerin in Lmna(ggHG/+) cells and farnesylation of progerin in Lmna(HG/+) cells was confirmed by metabolic labeling. Contrary to our expectations, Lmna(ggHG/+) mice survived longer than Lmna(HG/+) mice. The Lmna(ggHG/+) mice also exhibited milder bone disease. The steady-state levels of progerin, relative to lamin C, were lower in Lmna(ggHG/+) mice than in Lmna(HG/+) mice, providing a potential explanation for the milder disease in Lmna(ggHG/+) mice.
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Affiliation(s)
- Brandon S J Davies
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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168
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Varela I, Pereira S, Ugalde AP, Navarro CL, Suárez MF, Cau P, Cadiñanos J, Osorio FG, Foray N, Cobo J, de Carlos F, Lévy N, Freije JMP, López-Otín C. Combined treatment with statins and aminobisphosphonates extends longevity in a mouse model of human premature aging. Nat Med 2008; 14:767-72. [PMID: 18587406 DOI: 10.1038/nm1786] [Citation(s) in RCA: 294] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2008] [Accepted: 05/15/2008] [Indexed: 11/09/2022]
Abstract
Several human progerias, including Hutchinson-Gilford progeria syndrome (HGPS), are caused by the accumulation at the nuclear envelope of farnesylated forms of truncated prelamin A, a protein that is also altered during normal aging. Previous studies in cells from individuals with HGPS have shown that farnesyltransferase inhibitors (FTIs) improve nuclear abnormalities associated with prelamin A accumulation, suggesting that these compounds could represent a therapeutic approach for this devastating progeroid syndrome. We show herein that both prelamin A and its truncated form progerin/LADelta50 undergo alternative prenylation by geranylgeranyltransferase in the setting of farnesyltransferase inhibition, which could explain the low efficiency of FTIs in ameliorating the phenotypes of progeroid mouse models. We also show that a combination of statins and aminobisphosphonates efficiently inhibits both farnesylation and geranylgeranylation of progerin and prelamin A and markedly improves the aging-like phenotypes of mice deficient in the metalloproteinase Zmpste24, including growth retardation, loss of weight, lipodystrophy, hair loss and bone defects. Likewise, the longevity of these mice is substantially extended. These findings open a new therapeutic approach for human progeroid syndromes associated with nuclear-envelope abnormalities.
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Affiliation(s)
- Ignacio Varela
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Instituto Universitario de Oncología, Universidad de Oviedo, calle Fernando, Bongera s/n, 33006-Oviedo, Spain
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169
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Candelario J, Sudhakar S, Navarro S, Reddy S, Comai L. Perturbation of wild-type lamin A metabolism results in a progeroid phenotype. Aging Cell 2008; 7:355-67. [PMID: 18363904 DOI: 10.1111/j.1474-9726.2008.00393.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Mutations in the lamin A/C gene cause the rare genetic disorder Hutchinson-Gilford progeria syndrome (HGPS). The prevalent mutation results in the production of a mutant lamin A protein with an internal 50 amino acid deletion which causes a cellular aging phenotype characterized by growth defects, limited replicative lifespan, and nuclear membrane abnormalities. However, the relevance of these findings to normal human aging is unclear. In this study, we demonstrate that increased levels of wild-type lamin A in normal human cells result in decreased replicative lifespan and nuclear membrane abnormalities that lead to apoptotic cell death and senescence in a manner that is strongly reminiscent of the phenotype shown by HGPS cells. In contrast to the accelerated aging defects observed in HGPS cells, the progeroid phenotype resulting from increased expression of wild-type lamin A can be rescued by overexpression of ZMPSTE24, the metalloproteinase responsible for the removal of the farnesylated carboxyl terminal region of lamin A. Furthermore, farnesyltransferase inhibitors also serve to reverse the progeroid phenotype resulting from increased lamin A expression. Significantly, cells expressing elevated levels of lamin A display abnormal lamin A localization and similar alterations in the nuclear distribution of lamin A are also observed in cells from old-age individuals. These data demonstrate that the metabolism of wild-type lamin A is delicately poised and even in the absence of disease-linked mutations small perturbations in this system are sufficient to cause prominent nuclear defects and result in a progeroid phenotype.
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Affiliation(s)
- Jose Candelario
- Department of Molecular Microbiology and Immunology, Institute for Genetic Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
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170
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Verstraeten VLRM, Ji JY, Cummings KS, Lee RT, Lammerding J. Increased mechanosensitivity and nuclear stiffness in Hutchinson-Gilford progeria cells: effects of farnesyltransferase inhibitors. Aging Cell 2008; 7:383-93. [PMID: 18331619 DOI: 10.1111/j.1474-9726.2008.00382.x] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Hutchinson-Gilford progeria syndrome (HGPS), reportedly a model for normal aging, is a genetic disorder in children marked by dramatic signs suggestive for premature aging. It is usually caused by de novo mutations in the nuclear envelope protein lamin A. Lamins are essential to maintaining nuclear integrity, and loss of lamin A/C results in increased cellular sensitivity to mechanical strain and defective mechanotransduction signaling. Since increased mechanical sensitivity in vascular cells could contribute to loss of smooth muscle cells and the development of arteriosclerosis--the leading cause of death in HGPS patients--we investigated the effect of mechanical stress on cells from HGPS patients. We found that skin fibroblasts from HGPS patients developed progressively stiffer nuclei with increasing passage number. Importantly, fibroblasts from HGPS patients had decreased viability and increased apoptosis under repetitive mechanical strain, as well as attenuated wound healing, and these defects preceded changes in nuclear stiffness. Treating fibroblasts with farnesyltransferase inhibitors restored nuclear stiffness in HGPS cells and accelerated the wound healing response in HGPS and healthy control cells by increasing the directional persistence of migrating cells. However, farnesyltransferase inhibitors did not improve cellular sensitivity to mechanical strain. These data suggest that increased mechanical sensitivity in HGPS cells is unrelated to changes in nuclear stiffness and that increased biomechanical sensitivity could provide a potential mechanism for the progressive loss of vascular smooth muscle cells under physiological strain in HGPS patients.
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Affiliation(s)
- Valerie L R M Verstraeten
- Cardiovascular Division, Department of Medicine, Brigham & Women's Hospital/Harvard Medical School, Boston, MA 02115, USA
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171
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Rowat AC, Lammerding J, Herrmann H, Aebi U. Towards an integrated understanding of the structure and mechanics of the cell nucleus. Bioessays 2008; 30:226-36. [PMID: 18293361 DOI: 10.1002/bies.20720] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Changes in the shape and structural organization of the cell nucleus occur during many fundamental processes including development, differentiation and aging. In many of these processes, the cell responds to physical forces by altering gene expression within the nucleus. How the nucleus itself senses and responds to such mechanical cues is not well understood. In addition to these external forces, epigenetic modifications of chromatin structure inside the nucleus could also alter its physical properties. To achieve a better understanding, we need to elucidate the relationship between nuclear structure and material properties. Recently, new approaches have been developed to systematically investigate nuclear mechanical properties. These experiments provide important new insights into the disease mechanism of a growing class of tissue-specific disorders termed 'nuclear envelopathies'. Here we review our current understanding of what determines the shape and mechanical properties of the cell nucleus.
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Affiliation(s)
- Amy C Rowat
- Department of Physics/School of Engineering and Applied Science, Harvard University, Cambridge, MA 02138, USA.
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172
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Wang Y, Panteleyev AA, Owens DM, Djabali K, Stewart CL, Worman HJ. Epidermal expression of the truncated prelamin A causing Hutchinson-Gilford progeria syndrome: effects on keratinocytes, hair and skin. Hum Mol Genet 2008; 17:2357-69. [PMID: 18442998 DOI: 10.1093/hmg/ddn136] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Hutchinson-Gilford progeria syndrome (HGPS) is an accelerated aging disorder caused by point mutation in LMNA encoding A-type nuclear lamins. The mutations in LMNA activate a cryptic splice donor site, resulting in expression of a truncated, prenylated prelamin A called progerin. Expression of progerin leads to alterations in nuclear morphology, which may underlie pathology in HGPS. We generated transgenic mice expressing progerin in epidermis under control of a keratin 14 promoter. The mice had severe abnormalities in morphology of skin keratinocyte nuclei, including nuclear envelope lobulation and decreased nuclear circularity not present in transgenic mice expressing wild-type human lamin A. Primary keratinocytes isolated from these mice had a higher frequency of nuclei with abnormal shape compared to those from transgenic mice expressing wild-type human lamin A. Treatment with a farnesyltransferase inhibitor significantly improved nuclear shape abnormalities and induced the formation of intranuclear foci in the primary keratinocytes expressing progerin. Similarly, spontaneous immortalization of progerin-expressing cultured keratinocytes selected for cells with normal nuclear morphology. Despite morphological alterations in keratinocyte nuclei, mice expressing progerin in epidermis had normal hair grown and wound healing. Hair and skin thickness were normal even after crossing to Lmna null mice to reduce or eliminate expression of normal A-type lamins. Although progerin induces significant alterations in keratinocyte nuclear morphology that are reversed by inhibition of farnesyltransferasae, epidermal expression does not lead to alopecia or other skin abnormalities typically seen in human subjects with HGPS.
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Affiliation(s)
- Yuexia Wang
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
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173
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Pereira S, Bourgeois P, Navarro C, Esteves-Vieira V, Cau P, De Sandre-Giovannoli A, Lévy N. HGPS and related premature aging disorders: from genomic identification to the first therapeutic approaches. Mech Ageing Dev 2008; 129:449-59. [PMID: 18513784 DOI: 10.1016/j.mad.2008.04.003] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 03/27/2008] [Accepted: 04/06/2008] [Indexed: 01/25/2023]
Abstract
Progeroid syndromes are heritable human disorders displaying features that recall premature ageing. In these syndromes, premature aging is defined as "segmental" since only some of its features are accelerated. A number of cellular biological pathways have been linked to aging, including regulation of the insulin/growth hormone axis, pathways involving ROS metabolism, caloric restriction, and DNA repair. The number of identified genes associated with progeroid syndromes has increased in recent years, possibly shedding light as well on mechanisms underlying ageing in general. Among these, premature aging syndromes related to alterations of the LMNA gene have recently been identified. This review focuses on Hutchinson-Gilford Progeria syndrome and Restrictive Dermopathy, two well-characterized Lamin-associated premature aging syndromes, pointing out the current knowledge concerning their pathophysiology and the development of possible therapeutic approaches.
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Affiliation(s)
- Sandrine Pereira
- INSERM U910, Faculté de Médecine la Timone, 27 Boulevard Jean Moulin, Marseille, France
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174
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Dechat T, Pfleghaar K, Sengupta K, Shimi T, Shumaker DK, Solimando L, Goldman RD. Nuclear lamins: major factors in the structural organization and function of the nucleus and chromatin. Genes Dev 2008; 22:832-53. [PMID: 18381888 PMCID: PMC2732390 DOI: 10.1101/gad.1652708] [Citation(s) in RCA: 725] [Impact Index Per Article: 45.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Over the past few years it has become evident that the intermediate filament proteins, the types A and B nuclear lamins, not only provide a structural framework for the nucleus, but are also essential for many aspects of normal nuclear function. Insights into lamin-related functions have been derived from studies of the remarkably large number of disease-causing mutations in the human lamin A gene. This review provides an up-to-date overview of the functions of nuclear lamins, emphasizing their roles in epigenetics, chromatin organization, DNA replication, transcription, and DNA repair. In addition, we discuss recent evidence supporting the importance of lamins in viral infections.
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Affiliation(s)
- Thomas Dechat
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | - Katrin Pfleghaar
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | - Kaushik Sengupta
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | - Takeshi Shimi
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | - Dale K. Shumaker
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | - Liliana Solimando
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | - Robert D. Goldman
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
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175
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Liu Y, Wang Y, Rusinol AE, Sinensky MS, Liu J, Shell SM, Zou Y. Involvement of xeroderma pigmentosum group A (XPA) in progeria arising from defective maturation of prelamin A. FASEB J 2008; 22:603-11. [PMID: 17848622 PMCID: PMC3116236 DOI: 10.1096/fj.07-8598com] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cellular accumulation of DNA damage has been widely implicated in cellular senescence, aging, and premature aging. In Hutchinson-Gilford progeria syndrome (HGPS) and restrictive dermopathy (RD), premature aging is linked to accumulation of DNA double-strand breaks (DSBs), which results in genome instability. However, how DSBs accumulate in cells despite the presence of intact DNA repair proteins remains unknown. Here we report that the recruitment of DSB repair factors Rad50 and Rad51 to the DSB sites, as marked by gamma-H2AX, was impaired in human HGPS and Zmpste24-deficient cells. Consistently, the progeria-associated DSBs appeared to be unrepairable although DSBs induced by camptothecin were efficiently removed in the progeroid cells. We also found that these progeroid cells exhibited nuclear foci of xeroderma pigmentosum group A (XPA), a unique nucleotide excision repair protein. Strikingly, these XPA foci colocalized with the DSB sites in the progeroid cells. This XPA-DSB association was further confirmed and found to be mediated by DNA, using a modified chromatin immunoprecipitation assay and coimmunoprecipitation. RNA interference (RNAi) knockdown of XPA in HGPS cells partially restored DSB repair as evidenced by Western blot analysis, immunofluorescence and comet assays. We propose that the uncharacteristic localization of XPA to or near DSBs inhibits DSB repair, thereby contributing to the premature aging phenotypes observed in progeria arising from genetic defects in prelamin A maturation.
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Affiliation(s)
- Yiyong Liu
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614
| | - Youjie Wang
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614
| | - Antonio E. Rusinol
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614
| | - Michael S. Sinensky
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614
| | - Ji Liu
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614
- Department of Biochemistry and Molecular Biology, Sichuan University, Chengdu, China
| | - Steven M. Shell
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614
| | - Yue Zou
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614
- Department of Biochemistry and Molecular Biology, Sichuan University, Chengdu, China
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176
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Coffinier C, Hudon SE, Lee R, Farber EA, Nobumori C, Miner JH, Andres DA, Spielmann HP, Hrycyna CA, Fong LG, Young SG. A potent HIV protease inhibitor, darunavir, does not inhibit ZMPSTE24 or lead to an accumulation of farnesyl-prelamin A in cells. J Biol Chem 2008; 283:9797-804. [PMID: 18230615 DOI: 10.1074/jbc.m709629200] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
HIV protease inhibitors (HIV-PIs) are key components of highly active antiretroviral therapy, but they have been associated with adverse side effects, including partial lipodystrophy and metabolic syndrome. We recently demonstrated that a commonly used HIV-PI, lopinavir, inhibits ZMPSTE24, thereby blocking lamin A biogenesis and leading to an accumulation of prelamin A. ZMPSTE24 deficiency in humans causes an accumulation of prelamin A and leads to lipodystrophy and other disease phenotypes. Thus, an accumulation of prelamin A in the setting of HIV-PIs represents a plausible mechanism for some drug side effects. Here we show, with metabolic labeling studies, that lopinavir leads to the accumulation of the farnesylated form of prelamin A. We also tested whether a new and chemically distinct HIV-PI, darunavir, inhibits ZMPSTE24. We found that darunavir does not inhibit the biochemical activity of ZMPSTE24, nor does it lead to an accumulation of farnesyl-prelamin A in cells. This property of darunavir is potentially attractive. However, all HIV-PIs, including darunavir, are generally administered with ritonavir, an HIV-PI that is used to block the metabolism of other HIV-PIs. Ritonavir, like lopinavir, inhibits ZMPSTE24 and leads to an accumulation of prelamin A.
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Affiliation(s)
- Catherine Coffinier
- Department of Medicine and Human Genetics, David Geffen School of Medicine, University of California-Los Angeles, 695 Charles E. Young Drive South, Los Angeles, CA 90095, USA.
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177
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Cohen TV, Stewart CL. Fraying at the edge mouse models of diseases resulting from defects at the nuclear periphery. Curr Top Dev Biol 2008; 84:351-84. [PMID: 19186248 DOI: 10.1016/s0070-2153(08)00607-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Eukaryotic cells compartmentalize their genetic material within the nucleus. The boundary separating the genetic material from the cytoplasm is the nuclear envelope (NE) and lamina. Historically, the NE was perceived as functioning primarily as a barrier regulating the entry and exit of macromolecules between the nucleus and cytoplasm via the nuclear pore complexes (NPCs) that traverse the nuclear membranes. However, recent findings have caused a fundamental reassessment with regard to NE and lamina functions. Evidence now points to the NE and lamina functioning as a "hub" in regulating and perhaps integrating critical cellular functions that include chromatin organization, transcriptional regulation, mechanical integrity of the cell, signaling pathways, as well as acting as a key component of the cytoskeleton. Such an integral role for the nuclear boundary has emerged from increased interest into the functions of the NE/lamina, which has been largely stimulated by the discovery that some 24 different diseases and anomalies are caused by defects in proteins of the NE and lamina.
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Affiliation(s)
- Tatiana V Cohen
- Center for Genetic Medicine, Children's National Medical Center, N.W. Washington, DC 20010, USA
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178
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Maraldi NM, Capanni C, Lattanzi G, Camozzi D, Facchini A, Manzoli FA. SREBP1 interaction with prelamin A forms: A pathogenic mechanism for lipodystrophic laminopathies. ACTA ACUST UNITED AC 2008; 48:209-23. [DOI: 10.1016/j.advenzreg.2007.11.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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179
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Rankin J, Auer-Grumbach M, Bagg W, Colclough K, Duong NT, Fenton-May J, Hattersley A, Hudson J, Jardine P, Josifova D, Longman C, McWilliam R, Owen K, Walker M, Wehnert M, Ellard S. Extreme phenotypic diversity and nonpenetrance in families with theLMNA gene mutation R644C. Am J Med Genet A 2008; 146A:1530-42. [DOI: 10.1002/ajmg.a.32331] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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180
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The mutant form of lamin A that causes Hutchinson-Gilford progeria is a biomarker of cellular aging in human skin. PLoS One 2007; 2:e1269. [PMID: 18060063 PMCID: PMC2092390 DOI: 10.1371/journal.pone.0001269] [Citation(s) in RCA: 274] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2007] [Accepted: 11/10/2007] [Indexed: 01/11/2023] Open
Abstract
Hutchinson-Gilford progeria syndrome (HGPS, OMIM 176670) is a rare disorder characterized by accelerated aging and early death, frequently from stroke or coronary artery disease. 90% of HGPS cases carry the LMNA G608G (GGC>GGT) mutation within exon 11 of LMNA, activating a splice donor site that results in production of a dominant negative form of lamin A protein, denoted progerin. Screening 150 skin biopsies from unaffected individuals (newborn to 97 years) showed that a similar splicing event occurs in vivo at a low level in the skin at all ages. While progerin mRNA remains low, the protein accumulates in the skin with age in a subset of dermal fibroblasts and in a few terminally differentiated keratinocytes. Progerin-positive fibroblasts localize near the basement membrane and in the papillary dermis of young adult skin; however, their numbers increase and their distribution reaches the deep reticular dermis in elderly skin. Our findings demonstrate that progerin expression is a biomarker of normal cellular aging and may potentially be linked to terminal differentiation and senescence in elderly individuals.
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181
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Yang SH, Qiao X, Fong LG, Young SG. Treatment with a farnesyltransferase inhibitor improves survival in mice with a Hutchinson-Gilford progeria syndrome mutation. Biochim Biophys Acta Mol Cell Biol Lipids 2007; 1781:36-9. [PMID: 18082640 DOI: 10.1016/j.bbalip.2007.11.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Revised: 10/31/2007] [Accepted: 11/07/2007] [Indexed: 10/22/2022]
Abstract
Hutchinson-Gilford progeria syndrome (HGPS) is a progeroid syndrome characterized by multiple aging-like disease phenotypes. We recently reported that a protein farnesyltransferase inhibitor (FTI) improved several disease phenotypes in mice with a HGPS mutation (Lmna(HG/+)). Here, we investigated the impact of an FTI on the survival of Lmna(HG/+) mice. The FTI significantly improved the survival of both male and female Lmna(HG/+) mice. Treatment with the FTI also improved body weight curves and reduced the number of spontaneous rib fractures. This study provides further evidence for a beneficial effect of an FTI in HGPS.
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Affiliation(s)
- Shao H Yang
- Department of Medicine/Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
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182
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Moulson CL, Fong LG, Gardner JM, Farber EA, Go G, Passariello A, Grange DK, Young SG, Miner JH. Increased progerin expression associated with unusual LMNA mutations causes severe progeroid syndromes. Hum Mutat 2007; 28:882-9. [PMID: 17469202 DOI: 10.1002/humu.20536] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Hutchinson-Gilford progeria syndrome (HGPS) is a rare precocious aging syndrome caused by mutations in LMNA that lead to synthesis of a mutant form of prelamin A, generally called progerin, that cannot be processed to mature lamin A. Most HGPS patients have a recurrent heterozygous de novo mutation in exon 11 of LMNA, c.1824C>T/p.G608G; this synonymous mutation activates a nearby cryptic splice donor site, resulting in synthesis of the mutant prelamin A, progerin, which lacks 50 amino acids within the carboxyl-terminal domain. Abnormal splicing is incomplete, so the mutant allele produces some normally-spliced transcripts. Nevertheless, the synthesis of progerin is sufficient to cause misshapen nuclei in cultured cells and severe disease phenotypes in affected patients. Here we present two patients with extraordinarily severe forms of progeria caused by unusual mutations in LMNA. One had a splice site mutation (c.1968+1G>A; or IVS11+1G>A), and the other had a novel synonymous coding region mutation (c.1821G>A/p.V607V). Both mutations caused very frequent use of the same exon 11 splice donor site that is activated in typical HGPS patients. As a consequence, the ratios of progerin mRNA and protein to wild-type were higher than in typical HGPS patients. Fibroblasts from both patients exhibited nuclear shape abnormalities typical of HGPS, and cells treated with a protein farnesyltransferase inhibitor exhibited fewer misshapen nuclei. Thus, farnesyltransferase inhibitors may prove to be useful even when progerin expression levels are higher than those in typical HGPS patients.
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Affiliation(s)
- Casey L Moulson
- Department of Internal Medicine, Renal Division, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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183
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Abstract
Progeria (Hutchinson-Gilford progeria syndrome) is a rare genetic disorder that offers considerable insight into the biology of premature aging. This review summarizes the clinical characteristics of this disease and the underlying mutation in the lamin A (LMNA) gene that results in this phenotype. Modifications in the processing of prelamin A through alterations in farnesylation are detailed, because this pathway offers a possible drug target. Finally, discussion of an ongoing clinical trial for these children, including possible parameters for evaluation, are discussed. In the span of less than a decade, this disease has progressed from an interesting phenotype to one in which the gene defect has been identified, animal models have been created and tested with drugs that target the primary disease pathway, and significant clinical baseline data for the support of a clinical trial have been obtained.
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Affiliation(s)
- Mark W Kieran
- Dana-Farber Cancer Institute, Department of Pediatric Oncology, 44 Binney St, Boston, MA 02115, USA.
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184
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Gordon LB, McCarten KM, Giobbie-Hurder A, Machan JT, Campbell SE, Berns SD, Kieran MW. Disease progression in Hutchinson-Gilford progeria syndrome: impact on growth and development. Pediatrics 2007; 120:824-33. [PMID: 17908770 DOI: 10.1542/peds.2007-1357] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVES Hutchinson-Gilford progeria syndrome is a rare and uniformly fatal segmental "premature aging" disease that affects a variety of organ systems. We sought to more clearly define the bone and weight abnormalities in patients with progeria as potential outcome parameters for prospective clinical trials. PATIENTS AND METHODS We collected and analyzed longitudinal medical information, both retrospectively and prospectively, from a total of 41 children with Hutchinson-Gilford progeria syndrome spanning 14 countries, from the Progeria Research Foundation Medical and Research Database at the Brown University Center for Gerontology. RESULTS In addition to a number of previously well-defined phenotypic findings in children with progeria, this study identified abnormalities in the eruption of secondary incisors lingually and palatally in the mandible and maxilla, respectively. Although bony structures appeared normal in early infancy, clavicular resorption, coxa valga, avascular necrosis of the femoral head, modeling abnormalities of long bones with slender diaphyses, flared metaphyses, and overgrown epiphyses developed. Long bones showed normal cortical thickness centrally and progressive focal demineralization peripherally. The most striking finding identified in the retrospective data set of 35 children was an average weight increase of only 0.44 kg/year, beginning at approximately 24 months of age and persisting through life, with remarkable intrapatient linearity. This rate is >2 SD below normal weight gain for any corresponding age and sharply contrasts with the parabolic growth pattern for normal age- and gender-matched children. This finding was also confirmed prospectively. CONCLUSIONS Our analysis shows evidence of a newly identified abnormal growth pattern for children with Hutchinson-Gilford progeria syndrome. The skeletal and dental findings are suggestive of a developmental dysplasia rather than a classical aging process. The presence of decreased and linear weight gain, maintained in all of the patients after the age of 2 years, provides the ideal parameter on which altered disease status can be assessed in clinical trials.
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Affiliation(s)
- Leslie B Gordon
- Department of Pediatrics, Rhode Island Hospital, Providence, Rhode Island, USA.
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185
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Abstract
In the past several years, remarkable progress has been made in the understanding of the mechanisms of premature aging. These rare, genetic conditions offer valuable insights into the normal aging process and the complex biology of cardiovascular disease. Many of these advances have been made in the most dramatic of these disorders, Hutchinson–Gilford progeria syndrome. Although characterized by features of normal aging such as alopecia, skin wrinkling, and osteoporosis, patients with Hutchinson–Gilford progeria syndrome are affected by accelerated, premature arteriosclerotic disease that leads to heart attacks and strokes at a mean age of 13 years. In this review, we highlight recent advances in the biology of premature aging uncovered in Hutchinson–Gilford progeria syndrome and other accelerated aging syndromes, advances that provide insight into the mechanisms of cardiovascular diseases ranging from atherosclerosis to arrhythmias.
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Affiliation(s)
- Brian C Capell
- Genome Technology Branch, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD 20892-2486, USA
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186
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Caron M, Auclair M, Donadille B, Béréziat V, Guerci B, Laville M, Narbonne H, Bodemer C, Lascols O, Capeau J, Vigouroux C. Human lipodystrophies linked to mutations in A-type lamins and to HIV protease inhibitor therapy are both associated with prelamin A accumulation, oxidative stress and premature cellular senescence. Cell Death Differ 2007; 14:1759-67. [PMID: 17612587 DOI: 10.1038/sj.cdd.4402197] [Citation(s) in RCA: 147] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Lipodystrophic syndromes associated with mutations in LMNA, encoding A-type lamins, and with HIV antiretroviral treatments share several clinical characteristics. Nuclear alterations and prelamin A accumulation have been reported in fibroblasts from patients with LMNA mutations and adipocytes exposed to protease inhibitors (PI). As genetically altered lamin A maturation also results in premature ageing syndromes with lipodystrophy, we studied prelamin A expression and senescence markers in cultured human fibroblasts bearing six different LMNA mutations or treated with PIs. As compared to control cells, fibroblasts with LMNA mutations or treated with PIs had nuclear shape abnormalities and reduced proliferative activity that worsened with increasing cellular passages. They exhibited prelamin A accumulation, increased oxidative stress, decreased expression of mitochondrial respiratory chain proteins and premature cellular senescence. Inhibition of prelamin A farnesylation prevented cellular senescence and oxidative stress. Adipose tissue samples from patients with LMNA mutations or treated with PIs also showed retention of prelamin A, overexpression of the cell cycle checkpoint inhibitor p16 and altered mitochondrial markers. Thus, both LMNA mutations and PI treatment result in accumulation of farnesylated prelamin A and oxidative stress that trigger premature cellular senescence. These alterations could participate in the pathophysiology of lipodystrophic syndromes and lead to premature ageing complications.
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Affiliation(s)
- M Caron
- INSERM U680, Université Pierre et Marie Curie-Paris 6, Faculté de Médecine, Site Saint-Antoine, 27 rue Chaligny, 75571 Paris Cedex 12, France.
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187
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Kudlow BA, Kennedy BK, Monnat RJ. Werner and Hutchinson-Gilford progeria syndromes: mechanistic basis of human progeroid diseases. Nat Rev Mol Cell Biol 2007; 8:394-404. [PMID: 17450177 DOI: 10.1038/nrm2161] [Citation(s) in RCA: 206] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Progeroid syndromes have been the focus of intense research in part because they might provide a window into the pathology of normal ageing. Werner syndrome and Hutchinson-Gilford progeria syndrome are two of the best characterized human progeroid diseases. Mutated genes that are associated with these syndromes have been identified, mouse models of disease have been developed, and molecular studies have implicated decreased cell proliferation and altered DNA-damage responses as common causal mechanisms in the pathogenesis of both diseases.
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Affiliation(s)
- Brian A Kudlow
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
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188
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Hegele RA, Oshima J. Phenomics and lamins: From disease to therapy. Exp Cell Res 2007; 313:2134-43. [PMID: 17466974 DOI: 10.1016/j.yexcr.2007.03.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 03/19/2007] [Accepted: 03/22/2007] [Indexed: 11/19/2022]
Abstract
Systematic correlation of phenotype with genotype is a key goal of the emerging field of phenomics, which is expected to help define complex diseases. Careful evaluation of phenotype-genotype associations in monogenic disorders, such as laminopathies, might provide new hypotheses to be tested with molecular and cellular studies and might also suggest potential new intervention strategies. For instance, evaluation of the clinical features of carriers of mutant LMNA in kindreds with familial partial lipodystrophy suggests rational, staged intervention using established pharmaceutical agents to prevent cardiovascular complications not just for patients with lipodystrophy but by extension for patients with the common metabolic syndrome. Careful non-invasive imaging shows phenotypic differences between partial lipodystrophy due to mutant LMNA and not due to mutant LMNA. Furthermore, hierarchical cluster analysis detects systematic relationships between organ involvement in laminopathies and mutation position in the LMNA genomic sequence. However, sometimes the same LMNA mutation can underlie markedly different clinical phenotypes; cellular and molecular experiments can help to explain the mechanistic basis for such differences. Finally, promising novel treatment modalities for laminopathies, such as farnesyl transferase inhibition and gene-based therapies, might help not only to illuminate mechanisms that link genotype to phenotype, but also to provide hope for patients suffering with laminopathies, since these treatments are designed to modulate key early or proximal steps in the pathogenesis of these disorders.
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Affiliation(s)
- Robert A Hegele
- Schulich School of Medicine and Dentistry, University of Western Ontario and Vascular Biology Research Group, Robarts Research Institute, London, Ontario, Canada N6A 5K8.
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189
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Afilalo J, Sebag IA, Chalifour LE, Rivas D, Akter R, Sharma K, Duque G. Age-related changes in lamin A/C expression in cardiomyocytes. Am J Physiol Heart Circ Physiol 2007; 293:H1451-6. [PMID: 17513488 DOI: 10.1152/ajpheart.01194.2006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lamin A and C (A/C) are type V intermediate filaments that form the nuclear lamina. Lamin A/C mutations lead to reduced expression of lamin A/C and diverse phenotypes such as familial cardiomyopathies and accelerated aging syndromes. Normal aging is associated with reduced expression of lamin A/C in osteoblasts and dermal fibroblasts but has never been assessed in cardiomyocytes. Our objective was to compare the expression of lamin A/C in cardiomyocytes of old (24 mo) versus young (4 mo) C57Bl/6J mice using a well-validated mouse model of aging. Lamin B1 was used as a control. Immunohistochemical and immunofluorescence analyses showed reduced expression of lamin A/C in cardiomyocyte nuclei of old mice (proportion of nuclei expressing lamin A/C, 9% vs. 62%, P < 0.001). Lamin A/C distribution was scattered peripherally and perinuclear in old mice, whereas it was homogeneous throughout the nuclei in young mice. Western blot analyses confirmed reduced expression of lamin A/C in nuclear extracts of old mice (ratio of lamin A/C to B1, 0.6 vs. 1.2, P < 0.01). Echocardiographic studies showed increased left ventricular wall thickness with preserved cavity size (concentric remodeling), increased left ventricular mass, and a slight reduction in fractional shortening in old mice. This is the first study to show that normal aging is associated with reduced expression and altered distribution of lamin A/C in nuclei of cardiomyocytes.
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Affiliation(s)
- Jonathan Afilalo
- Division of Internal Medicine, Department of Medicine, Sir Mortimer B. Davis Jewish General Hospital, McGill University, Montréal, Québec, Canada
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190
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Stewart CL, Kozlov S, Fong LG, Young SG. Mouse models of the laminopathies. Exp Cell Res 2007; 313:2144-56. [PMID: 17493612 PMCID: PMC1949387 DOI: 10.1016/j.yexcr.2007.03.026] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2007] [Revised: 03/05/2007] [Accepted: 03/12/2007] [Indexed: 12/25/2022]
Abstract
The A and B type lamins are nuclear intermediate filament proteins that comprise the bulk of the nuclear lamina, a thin proteinaceous structure underlying the inner nuclear membrane. The A type lamins are encoded by the lamin A gene (LMNA). Mutations in this gene have been linked to at least nine diseases, including the progeroid diseases Hutchinson-Gilford progeria and atypical Werner's syndromes, striated muscle diseases including muscular dystrophies and dilated cardiomyopathies, lipodystrophies affecting adipose tissue deposition, diseases affecting skeletal development, and a peripheral neuropathy. To understand how different diseases arise from different mutations in the same gene, mouse lines carrying some of the same mutations found in the human diseases have been established. We, and others have generated mice with different mutations that result in progeria, muscular dystrophy, and dilated cardiomyopathy. To further our understanding of the functions of the lamins, we also created mice lacking lamin B1, as well as mice expressing only one of the A type lamins. These mouse lines are providing insights into the functions of the lamina and how changes to the lamina affect the mechanical integrity of the nucleus as well as signaling pathways that, when disrupted, may contribute to the disease.
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Affiliation(s)
- Colin L Stewart
- Laboratory of Cancer and Developmental Biology, National Cancer Institute, Frederick, Maryland 21702, USA.
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191
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Worman HJ, Bonne G. "Laminopathies": a wide spectrum of human diseases. Exp Cell Res 2007; 313:2121-33. [PMID: 17467691 PMCID: PMC2964355 DOI: 10.1016/j.yexcr.2007.03.028] [Citation(s) in RCA: 479] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2007] [Revised: 03/08/2007] [Accepted: 03/12/2007] [Indexed: 12/23/2022]
Abstract
Mutations in genes encoding the intermediate filament nuclear lamins and associated proteins cause a wide spectrum of diseases sometimes called "laminopathies." Diseases caused by mutations in LMNA encoding A-type lamins include autosomal dominant Emery-Dreifuss muscular dystrophy and related myopathies, Dunnigan-type familial partial lipodystrophy, Charcot-Marie-Tooth disease type 2B1 and developmental and accelerated aging disorders. Duplication in LMNB1 encoding lamin B1 causes autosomal dominant leukodystrophy and mutations in LMNB2 encoding lamin B2 are associated with acquired partial lipodystrophy. Disorders caused by mutations in genes encoding lamin-associated integral inner nuclear membrane proteins include X-linked Emery-Dreifuss muscular dystrophy, sclerosing bone dysplasias, HEM/Greenberg skeletal dysplasia and Pelger-Huet anomaly. While mutations and clinical phenotypes of "laminopathies" have been carefully described, data explaining pathogenic mechanisms are only emerging. Future investigations will likely identify new "laminopathies" and a combination of basic and clinical research will lead to a better understanding of pathophysiology and the development of therapies.
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Affiliation(s)
- Howard J Worman
- Department of Medicine, College of Physicians and Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, USA.
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192
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Abstract
Hutchinson-Gilford progeria syndrome (HGPS) is a rare but well known entity characterized by extreme short stature, low body weight, early loss of hair, lipodystrophy, scleroderma, decreased joint mobility, osteolysis, and facial features that resemble aged persons. Cardiovascular compromise leads to early demise. Cognitive development is normal. Data on 10 of our own cases and 132 cases from literature are presented. The incidence in the last century in the Netherlands was 1:4,000,000. Sex ratio was 1.2:1. Main first symptoms were failure to thrive (55%), hair loss (40%), skin problems (28%), and lipodystrophy (20%). Mean age at diagnosis was 2.9 years. Growth in weight was more disturbed than growth in height, and growth delay started already prenatally. Mean height > 13 years was 109.0 cm, mean weight was 14.5 kg. Osteolysis was wide-spread but not expressed, except in the viscerocranium, and remained limited to membranous formed bone. Lipodystrophy is generalized, only intra-abdominal fat depositions remain present. Cardiovascular problems are extremely variable, both in age of onset and nature. Stroke and coronary dysfunctioning are most frequent. Pathologic findings in coronaries and aorta resemble sometimes the findings in elderly persons, but can also be much more limited. Loss of smooth muscle cells seems the most important finding. Mean age of demise was 12.6 years. Patients can be subdivided in patients with classical HGPS, which follows an autosomal dominant pattern of inheritance, (almost) all cases representing spontaneous mutations, and in non-classical progeria, in whom growth can be less retarded, scalp hair remains present for a longer time, lipodystrophy is more slowly progressive, osteolysis is more expressed except in the face, and survival well into adulthood is not uncommon. Pattern of inheritance of non-classical progeria is most probably autosomal recessive. The cause of HGPS is an abnormally formed Lamin A, either directly by a mutated LMNA gene, or through abnormal posttranslational processing (ZMPSTE24 gene mutations). Of 34 LMNA mutations found in progeria patients, there were 26 classical p.G608G mutations (76%). Pathogenesis is most likely to follow several different pathways. Potential therapeutic strategies are developed along these lines and include RNA interference techniques and inhibition of the dominant-negative influence of abnormally formed Lamin A on polymerization with normally formed Lamin A.
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Affiliation(s)
- Raoul C M Hennekam
- Clinical and Molecular Genetics Unit, Institute of Child Health, Great Ormond Street Hospital, London, UK.
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193
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Abstract
Few genes have generated as much recent interest as LMNA, LMNB1 and LMNB2, which encode the components of the nuclear lamina. Over 180 mutations in these genes are associated with at least 13 known diseases--the laminopathies. In particular, the study of LMNA, its products and the phenotypes that result from its mutation have provided important insights into subjects ranging from transcriptional regulation, the cell biology of the nuclear lamina and mechanisms of ageing. Recent studies have begun the difficult task of correlating the genotypes of laminopathies with their phenotypes, and potential therapeutic strategies using existing drugs, modified oligonucleotides and RNAi are showing real promise for the treatment of these diseases.
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Affiliation(s)
- Brian C Capell
- Genome Technology Branch, National Human Genome Research Institute, National Institutes of Health, 50 South Drive MSC8004, Bethesda, Maryland 20892-8004, USA
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194
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Maraldi NM, Mattioli E, Lattanzi G, Columbaro M, Capanni C, Camozzi D, Squarzoni S, Manzoli FA. Prelamin A processing and heterochromatin dynamics in laminopathies. ACTA ACUST UNITED AC 2007; 47:154-67. [PMID: 17341429 DOI: 10.1016/j.advenzreg.2006.12.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Nadir M Maraldi
- Department of Anatomical Sciences, University of Bologna, Bologna, Italy; IGM-CNR, Unit of Bologna, c/o IOR, Bologna, Italy.
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195
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Abstract
The laminopathies are a diverse group of conditions caused by mutations in the LMNA gene (MIM*150330). LMNA encodes the nuclear envelope proteins lamin A and lamin C by utilization of an alternative splice site in exon 10. The human LMNA gene was identified in 1986 but it was another 13 years before it was found to be the causative gene for a disease, namely Emery Dreifuss muscular dystrophy. Since then, a further eight clearly defined phenotypes have been associated with LMNA mutations. The diversity of these phenotypes is striking with features such as premature ageing, axonal neuropathy, lipodystrophy and myopathy being seen. These phenotypes and the emerging genotype/phenotype correlations are the subject of this review.
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Affiliation(s)
- J Rankin
- Department of Clinical Genetics, Royal Devon & Exeter NHS Foundation Trust, Exeter, UK.
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196
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Liu Y, Rusinol A, Sinensky M, Wang Y, Zou Y. DNA damage responses in progeroid syndromes arise from defective maturation of prelamin A. J Cell Sci 2006; 119:4644-9. [PMID: 17062639 PMCID: PMC3105909 DOI: 10.1242/jcs.03263] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The genetic diseases Hutchinson-Gilford progeria syndrome (HGPS) and restrictive dermopathy (RD) arise from accumulation of farnesylated prelamin A because of defects in the lamin A maturation pathway. Both of these diseases exhibit symptoms that can be viewed as accelerated aging. The mechanism by which accumulation of farnesylated prelamin A leads to these accelerated aging phenotypes is not understood. Here we present evidence that in HGPS and RD fibroblasts, DNA damage checkpoints are persistently activated because of the compromise in genomic integrity. Inactivation of checkpoint kinases Ataxia-telangiectasia-mutated (ATM) and ATR (ATM- and Rad3-related) in these patient cells can partially overcome their early replication arrest. Treatment of patient cells with a protein farnesyltransferase inhibitor (FTI) did not result in reduction of DNA double-strand breaks and damage checkpoint signaling, although the treatment significantly reversed the aberrant shape of their nuclei. This suggests that DNA damage accumulation and aberrant nuclear morphology are independent phenotypes arising from prelamin A accumulation in these progeroid syndromes. Since DNA damage accumulation is an important contributor to the symptoms of HGPS, our results call into question the possibility of treatment of HGPS with FTIs alone.
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Affiliation(s)
- Yiyong Liu
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614
| | - Antonio Rusinol
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614
| | - Michael Sinensky
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614
| | - Youjie Wang
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614
| | - Yue Zou
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614
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197
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Abstract
Hutchinson-Gilford progeria syndrome (HGPS) is caused by a LMNA mutation that leads to the synthesis of a mutant prelamin A that is farnesylated but cannot be further processed to mature lamin A. A more severe progeroid disorder, restrictive dermopathy (RD), is caused by the loss of the prelamin A-processing enzyme, ZMPSTE24. The absence of ZMPSTE24 prevents the endoproteolytic processing of farnesyl-prelamin A to mature lamin A and leads to the accumulation of farnesyl-prelamin A. In both HGPS and RD, the farnesyl-prelamin A is targeted to the nuclear envelope, where it interferes with the integrity of the nuclear envelope and causes misshapen cell nuclei. Recent studies have shown that the frequency of misshapen nuclei can be reduced by treating cells with a farnesyltransferase inhibitor (FTI). Also, administering an FTI to mouse models of HGPS and RD ameliorates the phenotypes of progeria. These studies have prompted interest in testing the efficacy of FTIs in children with HGPS.
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Affiliation(s)
- Stephen G Young
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA.
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198
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Gelb MH, Brunsveld L, Hrycyna CA, Michaelis S, Tamanoi F, Van Voorhis WC, Waldmann H. Therapeutic intervention based on protein prenylation and associated modifications. Nat Chem Biol 2006; 2:518-28. [PMID: 16983387 PMCID: PMC2892741 DOI: 10.1038/nchembio818] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In eukaryotic cells, a specific set of proteins are modified by C-terminal attachment of 15-carbon farnesyl groups or 20-carbon geranylgeranyl groups that function both as anchors for fixing proteins to membranes and as molecular handles for facilitating binding of these lipidated proteins to other proteins. Additional modification of these prenylated proteins includes C-terminal proteolysis and methylation, and attachment of a 16-carbon palmitoyl group; these modifications augment membrane anchoring and alter the dynamics of movement of proteins between different cellular membrane compartments. The enzymes in the protein prenylation pathway have been isolated and characterized. Blocking protein prenylation is proving to be therapeutically useful for the treatment of certain cancers, infection by protozoan parasites and the rare genetic disease Hutchinson-Gilford progeria syndrome.
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Affiliation(s)
- Michael H Gelb
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA.
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199
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Zal T, Zal MA, Lotz C, Goergen CJ, Gascoigne NRJ. Spectral shift of fluorescent dye FM4-64 reveals distinct microenvironment of nuclear envelope in living cells. Traffic 2006; 7:1607-13. [PMID: 17052249 DOI: 10.1111/j.1600-0854.2006.00498.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report a distinct microenvironment within the nuclear envelope (NE) in living cells revealed by a spectral shift of the fluorescent dye FM4-64 (N-(3-triethylammoniumpropyl)-4-(p-diethylaminophenylhexatrienyl)-pyridinium 2Br). The dye readily translocated to the NE at physiological temperature where it exhibited enhanced fluorescence when excited at 620-650 nm in contrast to 480-520 nm excitation in the endocytic pathway and in the endoplasmic reticulum (ER). In vitro data indicated that the dye reveals an enrichment of negatively charged lipids, presumably due to local phospholipid synthesis. Dual-excitation imaging of FM4-64 in relation to lamina-associated polypeptide-1-green fluorescent protein during mitosis suggested that the disassembly of NE preserves microscale lipid complexes in the ER. Convolutions of NE in cancer or primary cells were readily visualized, and killing of tumor cells by T cells was marked by sudden loss of the long-wavelength excited fluorescence in the NE coincident with apoptosis. This report of FM4-64 as the first vital dye sensitive to the NE environment opens new ways for real-time visualization and functional studies of the NE.
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Affiliation(s)
- Tomasz Zal
- Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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200
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Abstract
Progeroid syndromes (PSs) constitute a group of disorders characterized by clinical features mimicking physiological aging at an early age. In some of these syndromes, biological hallmarks of aging are also present, whereas in others, a link with physiological aging, if any, remains to be elucidated. These syndromes are clinically and genetically heterogeneous and most of them, including Werner syndrome and Hutchinson-Gilford progeria, are known as 'segmental aging syndromes', as they do not feature all aspects usually associated to physiological aging. However, all the characterized PSs enter in the field of rare monogenic disorders and several causative genes have been identified. These can be separated in subcategories corresponding to (i) genes encoding DNA repair factors, in particular, DNA helicases, and (ii) genes affecting the structure or post-translational maturation of lamin A, a major nuclear component. In addition, several animal models featuring premature aging have abnormal mitochondrial function or signal transduction between membrane receptors, nuclear regulatory proteins and mitochondria: no human pathological counterpart of these alterations has been found to date. In recent years, identification of mutations and their functional characterization have helped to unravel the cellular processes associated to segmental PSs. Recently, several studies allowed to establish a functional link between DNA repair and A-type lamins-associated syndromes, evidencing a relation between these syndromes, physiological aging and cancer. Here, we review recent data on molecular and cellular bases of PSs and discuss the mechanisms involved, with a special emphasis on lamin A-associated progeria and related disorders, for which therapeutic approaches have started to be developed.
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Affiliation(s)
- Claire L Navarro
- Inserm U491, Génétique Médicale et Développement, Université de la Méditerranée, Faculté de Médecine, 13385 Marseille Cedex 05, France
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