1
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Meek K, Yang YT, Takada M, Parys M, Richter M, Engleberg AI, Thaiwong T, Griffin RL, Schall PZ, Kramer AJ, Yuzbasiyan-Gurkan V. Identification of a Hypomorphic FANCG Variant in Bernese Mountain Dogs. Genes (Basel) 2022; 13:1693. [PMID: 36292578 PMCID: PMC9601343 DOI: 10.3390/genes13101693] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/12/2022] [Accepted: 09/19/2022] [Indexed: 05/26/2024] Open
Abstract
Bernese mountain dogs (BMDs), have an overall cancer incidence of 50%, half of which is comprised of an otherwise rare tumor, histiocytic sarcoma (HS). While recent studies have identified driver mutations in the MAPK pathway, identification of key predisposing genes has been elusive. Studies have identified several loci to be associated with predisposition to HS in BMDs, including near the MTAP/CDKN2A region, but no causative coding variant has been identified. Here we report the presence of a coding polymorphism in the gene encoding FANCG, near the MTAP/CDKN2A locus. This variant is in a conserved region of the protein and appears to be specific to BMDs. Canine fibroblasts derived from dogs homozygous for this variant are hypersensitive to cisplatin. We show this canine FANCG variant and a previously defined hypomorphic FANCG allele in humans impart similar defects in DNA repair. However, our data also indicate that this variant is neither necessary nor sufficient for the development of HS. Furthermore, BMDs homozygous for this FANCG allele display none of the characteristic phenotypes associated with Fanconi anemia (FA) such as anemia, short stature, infertility, or an earlier age of onset for HS. This is similar to findings in FA deficient mice, which do not develop overt FA without secondary genetic mutations that exacerbate the FA deficit. In sum, our data suggest that dogs with deficits in the FA pathway are, like mice, innately resistant to the development of FA.
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Affiliation(s)
- Katheryn Meek
- Comparative Medicine and Integrative Biology Program, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
- Department of Microbiology and Molecular Genetics, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - Ya-Ting Yang
- Comparative Medicine and Integrative Biology Program, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - Marilia Takada
- Comparative Medicine and Integrative Biology Program, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - Maciej Parys
- Comparative Medicine and Integrative Biology Program, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - Marlee Richter
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - Alexander I. Engleberg
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - Tuddow Thaiwong
- Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48190, USA
| | - Rachel L. Griffin
- College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - Peter Z. Schall
- Comparative Medicine and Integrative Biology Program, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - Alana J. Kramer
- College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
| | - Vilma Yuzbasiyan-Gurkan
- Comparative Medicine and Integrative Biology Program, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
- Department of Microbiology and Molecular Genetics, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
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2
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Gianni P, Matenoglou E, Geropoulos G, Agrawal N, Adnani H, Zafeiropoulos S, Miyara SJ, Guevara S, Mumford JM, Molmenti EP, Giannis D. The Fanconi anemia pathway and Breast Cancer: A comprehensive review of clinical data. Clin Breast Cancer 2021; 22:10-25. [PMID: 34489172 DOI: 10.1016/j.clbc.2021.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 07/17/2021] [Accepted: 08/05/2021] [Indexed: 02/08/2023]
Abstract
The development of breast cancer depends on several risk factors, including environmental, lifestyle and genetic factors. Despite the evolution of DNA sequencing techniques and biomarker detection, the epidemiology and mechanisms of various breast cancer susceptibility genes have not been elucidated yet. Dysregulation of the DNA damage response causes genomic instability and increases the rate of mutagenesis and the risk of carcinogenesis. The Fanconi Anemia (FA) pathway is an important component of the DNA damage response and plays a critical role in the repair of DNA interstrand crosslinks and genomic stability. The FA pathway involves 22 recognized genes and specific mutations have been identified as the underlying defect in the majority of FA patients. A thorough understanding of the function and epidemiology of these genes in breast cancer is critical for the development and implementation of individualized therapies that target unique tumor profiles. Targeted therapies (PARP inhibitors) exploiting the FA pathway gene defects have been developed and have shown promising results. This narrative review summarizes the current literature on the involvement of FA genes in sporadic and familial breast cancer with a focus on clinical data derived from large cohorts.
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Affiliation(s)
- Panagiota Gianni
- Department of Internal Medicine III, Hematology, Oncology, Palliative Medicine, Rheumatology and Infectious Diseases, University Hospital Ulm, Germany
| | - Evangelia Matenoglou
- Medical School, Aristotle University of Thessaloniki, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Georgios Geropoulos
- Thoracic Surgery Department, University College London Hospitals NHS Foundation Trust, London
| | - Nirav Agrawal
- Feinstein Institutes for Medical Research at Northwell Health, Manhasset, New York, NY
| | - Harsha Adnani
- Feinstein Institutes for Medical Research at Northwell Health, Manhasset, New York, NY
| | - Stefanos Zafeiropoulos
- Feinstein Institutes for Medical Research at Northwell Health, Manhasset, New York, NY; Elmezzi Graduate School of Molecular Medicine, Northwell Health, Manhasset, New York, NY
| | - Santiago J Miyara
- Feinstein Institutes for Medical Research at Northwell Health, Manhasset, New York, NY; Elmezzi Graduate School of Molecular Medicine, Northwell Health, Manhasset, New York, NY
| | - Sara Guevara
- Department of Surgery, North Shore University Hospital, Manhasset, New York, NY
| | - James M Mumford
- Department of Family Medicine, Glen Cove Hospital, Glen Cove, New York, NY; Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Hempstead, New York, NY
| | - Ernesto P Molmenti
- Feinstein Institutes for Medical Research at Northwell Health, Manhasset, New York, NY; Department of Surgery, North Shore University Hospital, Manhasset, New York, NY; Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Hempstead, New York, NY
| | - Dimitrios Giannis
- Feinstein Institutes for Medical Research at Northwell Health, Manhasset, New York, NY.
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3
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Izert MA, Szybowska PE, Górna MW, Merski M. The Effect of Mutations in the TPR and Ankyrin Families of Alpha Solenoid Repeat Proteins. FRONTIERS IN BIOINFORMATICS 2021; 1:696368. [PMID: 36303725 PMCID: PMC9581033 DOI: 10.3389/fbinf.2021.696368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 06/22/2021] [Indexed: 11/20/2022] Open
Abstract
Protein repeats are short, highly similar peptide motifs that occur several times within a single protein, for example the TPR and Ankyrin repeats. Understanding the role of mutation in these proteins is complicated by the competing facts that 1) the repeats are much more restricted to a set sequence than non-repeat proteins, so mutations should be harmful much more often because there are more residues that are heavily restricted due to the need of the sequence to repeat and 2) the symmetry of the repeats in allows the distribution of functional contributions over a number of residues so that sometimes no specific site is singularly responsible for function (unlike enzymatic active site catalytic residues). To address this issue, we review the effects of mutations in a number of natural repeat proteins from the tetratricopeptide and Ankyrin repeat families. We find that mutations are context dependent. Some mutations are indeed highly disruptive to the function of the protein repeats while mutations in identical positions in other repeats in the same protein have little to no effect on structure or function.
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Affiliation(s)
| | | | | | - Matthew Merski
- *Correspondence: Maria Wiktoria Górna, ; Matthew Merski,
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4
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Abstract
Fodrin and its erythroid cell-specific isoform spectrin are actin-associated fibrous proteins that play crucial roles in the maintenance of structural integrity in mammalian cells, which is necessary for proper cell function. Normal cell morphology is altered in diseases such as various cancers and certain neuronal disorders. Fodrin and spectrin are two-chain (αβ) molecules that are encoded by paralogous genes and share many features but also demonstrate certain differences. Fodrin (in humans, typically a heterodimer of the products of the SPTAN1 and SPTBN1 genes) is expressed in nearly all cell types and is especially abundant in neuronal tissues, whereas spectrin (in humans, a heterodimer of the products of the SPTA1 and SPTB1 genes) is expressed almost exclusively in erythrocytes. To fulfill a role in such a variety of different cell types, it was anticipated that fodrin would need to be a more versatile scaffold than spectrin. Indeed, as summarized here, domains unique to fodrin and its regulation by Ca2+, calmodulin, and a variety of posttranslational modifications (PTMs) endow fodrin with additional specific functions. However, how fodrin structural variations and misregulated PTMs may contribute to the etiology of various cancers and neurodegenerative diseases needs to be further investigated.
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5
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Lambert MW. The functional importance of lamins, actin, myosin, spectrin and the LINC complex in DNA repair. Exp Biol Med (Maywood) 2019; 244:1382-1406. [PMID: 31581813 PMCID: PMC6880146 DOI: 10.1177/1535370219876651] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Three major proteins in the nucleoskeleton, lamins, actin, and spectrin, play essential roles in maintenance of nuclear architecture and the integrity of the nuclear envelope, in mechanotransduction and mechanical coupling between the nucleoskeleton and cytoskeleton, and in nuclear functions such as regulation of gene expression, transcription and DNA replication. Less well known, but critically important, are the role these proteins play in DNA repair. The A-type and B-type lamins, nuclear actin and myosin, spectrin and the LINC (linker of nucleoskeleton and cytoskeleton) complex each function in repair of DNA damage utilizing various repair pathways. The lamins play a role in repair of DNA double-strand breaks (DSBs) by nonhomologous end joining (NHEJ) or homologous recombination (HR). Actin is involved in repair of DNA DSBs and interacts with myosin in facilitating relocalization of these DSBs in heterochromatin for HR repair. Nonerythroid alpha spectrin (αSpII) plays a critical role in repair of DNA interstrand cross-links (ICLs) where it acts as a scaffold in recruitment of repair proteins to sites of damage and is important in the initial damage recognition and incision steps of the repair process. The LINC complex contributes to the repair of DNA DSBs and ICLs. This review will address the important functions of these proteins in the DNA repair process, their mechanism of action, and the profound impact a defect or deficiency in these proteins has on cellular function. The critical roles of these proteins in DNA repair will be further emphasized by discussing the human disorders and the pathophysiological changes that result from or are related to deficiencies in these proteins. The demonstrated function for each of these proteins in the DNA repair process clearly indicates that there is another level of complexity that must be considered when mechanistically examining factors crucial for DNA repair.
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Affiliation(s)
- Muriel W Lambert
- Department of Pathology, Immunology and Laboratory
Medicine, Rutgers New Jersey Medical School, Newark, NJ 07103, USA
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6
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Goodman SR, Johnson D, Youngentob SL, Kakhniashvili D. The Spectrinome: The Interactome of a Scaffold Protein Creating Nuclear and Cytoplasmic Connectivity and Function. Exp Biol Med (Maywood) 2019; 244:1273-1302. [PMID: 31483159 DOI: 10.1177/1535370219867269] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
We provide a review of Spectrin isoform function in the cytoplasm, the nucleus, the cell surface, and in intracellular signaling. We then discuss the importance of Spectrin’s E2/E3 chimeric ubiquitin conjugating and ligating activity in maintaining cellular homeostasis. Finally we present spectrin isoform subunit specific human diseases. We have created the Spectrinome, from the Human Proteome, Human Reactome and Human Atlas data and demonstrated how it can be a useful tool in visualizing and understanding spectrins myriad of cellular functions.Impact statementSpectrin was for the first 12 years after its discovery thought to be found only in erythrocytes. In 1981, Goodman and colleagues1found that spectrin-like molecules were ubiquitously found in non-erythroid cells leading to a great multitude of publications over the next thirty eight years. The discovery of multiple spectrin isoforms found associated with every cellular compartment, and representing 2-3% of cellular protein, has brought us to today’s understanding that spectrin is a scaffolding protein, with its own E2/E3 chimeric ubiquitin conjugating ligating activity that is involved in virtually every cellular function. We cover the history, localized functions of spectrin isoforms, human diseases caused by mutations, and provide the spectrinome: a useful tool for understanding the myriad of functions for one of the most important proteins in all eukaryotic cells.
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Affiliation(s)
- Steven R Goodman
- Department of Pediatrics, Memphis Institute of Regenerative Medicine, The University of Tennessee Health Science Center, Memphis, TN 38103
| | - Daniel Johnson
- Department of Pediatrics, Memphis Institute of Regenerative Medicine, The University of Tennessee Health Science Center, Memphis, TN 38103
| | - Steven L Youngentob
- Department of Anatomy and Neurobiology, Memphis Institute of Regenerative Medicine, The University of Tennessee Health Science Center, Memphis, TN 38103
| | - David Kakhniashvili
- Department of Pediatrics, Memphis Institute of Regenerative Medicine, The University of Tennessee Health Science Center, Memphis, TN 38103
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7
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Lambert MW. Spectrin and its interacting partners in nuclear structure and function. Exp Biol Med (Maywood) 2019; 243:507-524. [PMID: 29557213 DOI: 10.1177/1535370218763563] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Nonerythroid αII-spectrin is a structural protein whose roles in the nucleus have just begun to be explored. αII-spectrin is an important component of the nucleoskelelton and has both structural and non-structural functions. Its best known role is in repair of DNA ICLs both in genomic and telomeric DNA. αII-spectrin aids in the recruitment of repair proteins to sites of damage and a proposed mechanism of action is presented. It interacts with a number of different groups of proteins in the nucleus, indicating it has roles in additional cellular functions. αII-spectrin, in its structural role, associates/co-purifies with proteins important in maintaining the architecture and mechanical properties of the nucleus such as lamin, emerin, actin, protein 4.1, nuclear myosin, and SUN proteins. It is important for the resilience and elasticity of the nucleus. Thus, αII-spectrin's role in cellular functions is complex due to its structural as well as non-structural roles and understanding the consequences of a loss or deficiency of αII-spectrin in the nucleus is a significant challenge. In the bone marrow failure disorder, Fanconi anemia, there is a deficiency in αII-spectrin and, among other characteristics, there is defective DNA repair, chromosome instability, and congenital abnormalities. One may speculate that a deficiency in αII-spectrin plays an important role not only in the DNA repair defect but also in the congenital anomalies observed in Fanconi anemia , particularly since αII-spectrin has been shown to be important in embryonic development in a mouse model. The dual roles of αII-spectrin in the nucleus in both structural and non-structural functions make this an extremely important protein which needs to be investigated further. Such investigations should help unravel the complexities of αII-spectrin's interactions with other nuclear proteins and enhance our understanding of the pathogenesis of disorders, such as Fanconi anemia , in which there is a deficiency in αII-spectrin. Impact statement The nucleoskeleton is critical for maintaining the architecture and functional integrity of the nucleus. Nonerythroid α-spectrin (αIISp) is an essential nucleoskeletal protein; however, its interactions with other structural and non-structural nuclear proteins and its functional importance in the nucleus have only begun to be explored. This review addresses these issues. It describes αIISp's association with DNA repair proteins and at least one proposed mechanism of action for its role in DNA repair. Specific interactions of αIISp with other nucleoskeletal proteins as well as its important role in the biomechanical properties of the nucleus are reviewed. The consequences of loss of αIISp, in disorders such as Fanconi anemia, are examined, providing insights into the profound impact of this loss on critical processes known to be abnormal in FA, such as development, carcinogenesis, cancer progression and cellular functions dependent upon αIISp's interactions with other nucleoskeletal proteins.
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Affiliation(s)
- Muriel W Lambert
- Department of Pathology and Laboratory Medicine, Rutgers New Jersey Medical School, The State University of New Jersey, Newark, NJ 07103, USA
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8
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Faridounnia M, Folkers GE, Boelens R. Function and Interactions of ERCC1-XPF in DNA Damage Response. Molecules 2018; 23:E3205. [PMID: 30563071 PMCID: PMC6320978 DOI: 10.3390/molecules23123205] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 11/27/2018] [Accepted: 12/01/2018] [Indexed: 12/28/2022] Open
Abstract
Numerous proteins are involved in the multiple pathways of the DNA damage response network and play a key role to protect the genome from the wide variety of damages that can occur to DNA. An example of this is the structure-specific endonuclease ERCC1-XPF. This heterodimeric complex is in particular involved in nucleotide excision repair (NER), but also in double strand break repair and interstrand cross-link repair pathways. Here we review the function of ERCC1-XPF in various DNA repair pathways and discuss human disorders associated with ERCC1-XPF deficiency. We also overview our molecular and structural understanding of XPF-ERCC1.
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Affiliation(s)
- Maryam Faridounnia
- Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
| | - Gert E Folkers
- Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
| | - Rolf Boelens
- Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
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9
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De Muyt A, Pyatnitskaya A, Andréani J, Ranjha L, Ramus C, Laureau R, Fernandez-Vega A, Holoch D, Girard E, Govin J, Margueron R, Couté Y, Cejka P, Guérois R, Borde V. A meiotic XPF-ERCC1-like complex recognizes joint molecule recombination intermediates to promote crossover formation. Genes Dev 2018; 32:283-296. [PMID: 29440262 PMCID: PMC5859969 DOI: 10.1101/gad.308510.117] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 01/24/2018] [Indexed: 11/24/2022]
Abstract
De Muyt et al. identified the ZZS (Zip2–Zip4–Spo16) complex, required for crossover formation, which carries two distinct activities: one provided by Zip4, which acts as hub through physical interactions with components of the chromosome axis and the crossover machinery, and the other carried by Zip2 and Spo16, which preferentially bind branched DNA molecules in vitro. Meiotic crossover formation requires the stabilization of early recombination intermediates by a set of proteins and occurs within the environment of the chromosome axis, a structure important for the regulation of meiotic recombination events. The molecular mechanisms underlying and connecting crossover recombination and axis localization are elusive. Here, we identified the ZZS (Zip2–Zip4–Spo16) complex, required for crossover formation, which carries two distinct activities: one provided by Zip4, which acts as hub through physical interactions with components of the chromosome axis and the crossover machinery, and the other carried by Zip2 and Spo16, which preferentially bind branched DNA molecules in vitro. We found that Zip2 and Spo16 share structural similarities to the structure-specific XPF–ERCC1 nuclease, although it lacks endonuclease activity. The XPF domain of Zip2 is required for crossover formation, suggesting that, together with Spo16, it has a noncatalytic DNA recognition function. Our results suggest that the ZZS complex shepherds recombination intermediates toward crossovers as a dynamic structural module that connects recombination events to the chromosome axis. The identification of the ZZS complex improves our understanding of the various activities required for crossover implementation and is likely applicable to other organisms, including mammals.
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Affiliation(s)
- Arnaud De Muyt
- UMR3244, Centre Nationnal de la Recherche Scientifique (CNRS), Institut Curie, PSL (Paris Sciences and Letters) Research University, 75005 Paris, France.,Université Pierre et Marie Curie (UPMC), 75005 Paris, France
| | - Alexandra Pyatnitskaya
- UMR3244, Centre Nationnal de la Recherche Scientifique (CNRS), Institut Curie, PSL (Paris Sciences and Letters) Research University, 75005 Paris, France.,Université Pierre et Marie Curie (UPMC), 75005 Paris, France
| | - Jessica Andréani
- Institut de Biologie Intégrative de la Cellule (I2BC), Institut de biologie et de technologies de Saclay (iBiTec-S), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), UMR9198, CNRS, Université Paris-Sud, 91190 Gif-sur-Yvette, France.,Université Paris Sud, 91400 Orsay, France
| | - Lepakshi Ranjha
- Institute for Research in Biomedicine, Università della Svizzera italiana, 6500 Bellinzona, Switzerland
| | - Claire Ramus
- University of Grenoble Alpes, CEA, Institut National de la Santé et de la Recherche Médicale (INSERM), Institut de Biosciences et Biotechnologies de Grenoble (BIG-BGE), 38000 Grenoble, France
| | - Raphaëlle Laureau
- UMR3244, Centre Nationnal de la Recherche Scientifique (CNRS), Institut Curie, PSL (Paris Sciences and Letters) Research University, 75005 Paris, France.,Université Pierre et Marie Curie (UPMC), 75005 Paris, France
| | - Ambra Fernandez-Vega
- UMR3244, Centre Nationnal de la Recherche Scientifique (CNRS), Institut Curie, PSL (Paris Sciences and Letters) Research University, 75005 Paris, France.,Université Pierre et Marie Curie (UPMC), 75005 Paris, France
| | - Daniel Holoch
- Université Pierre et Marie Curie (UPMC), 75005 Paris, France.,Institut Curie, PSL Research University, UMR934, CNRS, 75005 Paris, France
| | - Elodie Girard
- Institut Curie, PSL Research University, Mines ParisTech, U900, INSERM, 75005 Paris, France
| | - Jérome Govin
- University of Grenoble Alpes, CEA, Institut National de la Santé et de la Recherche Médicale (INSERM), Institut de Biosciences et Biotechnologies de Grenoble (BIG-BGE), 38000 Grenoble, France
| | - Raphaël Margueron
- Université Pierre et Marie Curie (UPMC), 75005 Paris, France.,Institut Curie, PSL Research University, UMR934, CNRS, 75005 Paris, France
| | - Yohann Couté
- University of Grenoble Alpes, CEA, Institut National de la Santé et de la Recherche Médicale (INSERM), Institut de Biosciences et Biotechnologies de Grenoble (BIG-BGE), 38000 Grenoble, France
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera italiana, 6500 Bellinzona, Switzerland.,Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH) Zurich, 8093 Zurich, Switzerland
| | - Raphaël Guérois
- Institut de Biologie Intégrative de la Cellule (I2BC), Institut de biologie et de technologies de Saclay (iBiTec-S), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), UMR9198, CNRS, Université Paris-Sud, 91190 Gif-sur-Yvette, France.,Université Paris Sud, 91400 Orsay, France
| | - Valérie Borde
- UMR3244, Centre Nationnal de la Recherche Scientifique (CNRS), Institut Curie, PSL (Paris Sciences and Letters) Research University, 75005 Paris, France.,Université Pierre et Marie Curie (UPMC), 75005 Paris, France
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10
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Characterization of two novel FANCG mutations in Indian Fanconi anemia patients. Leuk Res 2016; 53:50-56. [PMID: 28024295 DOI: 10.1016/j.leukres.2016.11.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 11/23/2016] [Accepted: 11/28/2016] [Indexed: 01/25/2023]
Abstract
FA is a rare recessive genetic disorder with autosomal or X-linked mode of inheritance and is associated with 19 different FA complementation groups. We have studied three patients clinically diagnosed as FA. All three patients showed a high frequency chromosomal breakage in MMC induced blood cultures and FANCD2 non-monoubiquitination by western blotting. The molecular analysis using direct sequencing revealed two novel mutations in FANCG; 2 novel mutations c.1143+5G>C and c.883dupG, and a reported mutation c.1471_1473delAAAinsG. We have for the first time modeled FANCG protein with fold based template search using pGenthreader which revealed sequence fold identical to super helical TPR domain of O linked GLCNAC transferase and have studied the impact of mutations on the function and structure of FANCG. All three mutations are potential pathogenic molecular changes which can affect FANCG interactions required for FA pathway, homologous recombination repairs and unhooking step of the ICL repair process.
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11
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Lambert MW. Nuclear alpha spectrin: Critical roles in DNA interstrand cross-link repair and genomic stability. Exp Biol Med (Maywood) 2016; 241:1621-38. [PMID: 27480253 PMCID: PMC4999628 DOI: 10.1177/1535370216662714] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Non-erythroid alpha spectrin (αIISp) is a structural protein which we have shown is present in the nucleus of human cells. It interacts with a number of nuclear proteins such as actin, lamin, emerin, chromatin remodeling factors, and DNA repair proteins. αIISp's interaction with DNA repair proteins has been extensively studied. We have demonstrated that nuclear αIISp is critical in DNA interstrand cross-link (ICL) repair in S phase, in both genomic (non-telomeric) and telomeric DNA, and in maintenance of genomic stability following ICL damage to DNA. We have proposed that αIISp acts as a scaffold aiding to recruit repair proteins to sites of damage. This involvement of αIISp in ICL repair and telomere maintenance after ICL damage represents new and critical functions for αIISp. These studies have led to development of a model for the role of αIISp in DNA ICL repair. They have been aided by examination of cells from patients with Fanconi anemia (FA), a repair-deficient genetic disorder in which a deficiency in αIISp leads to defective ICL repair in genomic and telomeric DNA, telomere dysfunction, and chromosome instability following DNA ICL damage. We have shown that loss of αIISp in FA cells is due to increased breakdown by the protease, µ-calpain. Importantly, we have demonstrated that this deficiency can be corrected by knockdown of µ-calpain and restoring αIISp levels to normal. This corrects a number of the phenotypic deficiencies in FA after ICL damage. These studies suggest a new and unexplored direction for therapeutically restoring genomic stability in FA cells and for correcting numerous phenotypic deficiencies occurring after ICL damage. Developing a more in-depth understanding of the importance of the interaction of αIISp with other nuclear proteins could significantly enhance our knowledge of the consequences of loss of αIISp on critical nuclear processes.
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Affiliation(s)
- Muriel W Lambert
- Department of Pathology and Laboratory Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
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12
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Lambert MW. Functional Significance of Nuclear α Spectrin. J Cell Biochem 2016; 116:1816-30. [PMID: 25757157 DOI: 10.1002/jcb.25123] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 02/03/2015] [Indexed: 11/11/2022]
Abstract
Nonerythroid alpha spectrin (αIISp) interacts in the nucleus with an array of different proteins indicating its involvement in a number of diverse functions. However, the significance of these interactions and their functional importance has been a relatively unexplored area. The best documented role of nuclear αIISp is in DNA repair where it is critical for repair of DNA interstrand cross-links (ICLs), acting as a scaffold recruiting proteins to sites of damage in genomic and telomeric DNA. A deficiency in αIISp can importantly impact DNA ICL repair as is seen in cells from patients with the genetic disorder, Fanconi anemia (FA), where loss of αIISp leads to not only defects in repair of both genomic and telomeric DNA but also to telomere dysfunction and chromosome instability. This previously unexplored link between αIISp and telomere function is important in developing an understanding of maintenance of genomic stability after ICL damage. In FA cells, these defects in chromosome instability after ICL damage can be corrected when levels of αIISp are returned to normal by knocking down μ-calpain, a protease which cleaves αIISp. These studies suggest a new direction for correcting a number of the phenotypic defects in FA and could serve as a basis for therapeutic intervention. More in depth, examination of the interactions of αIISp with other proteins in the nucleus is of major importance in development of insights into the interacting key elements involved in the diverse processes occurring in the nucleus and the consequences loss of αIISp has on them.
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Affiliation(s)
- Muriel W Lambert
- Department of Pathology and Laboratory Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, 185 South Orange Avenue, Newark, New Jersey, 07103
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Zhang P, Sridharan D, Lambert MW. Nuclear α Spectrin Differentially Affects Monoubiquitinated Versus Non-Ubiquitinated FANCD2 Function After DNA Interstrand Cross-Link Damage. J Cell Biochem 2015; 117:671-83. [PMID: 26297932 DOI: 10.1002/jcb.25352] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 08/19/2015] [Indexed: 01/21/2023]
Abstract
Nonerythroid α spectrin (αIISp) and the Fanconi anemia (FA) protein, FANCD2, play critical roles in DNA interstrand cross-link (ICL) repair during S phase. Both are needed for recruitment of repair proteins, such as XPF, to sites of damage and repair of ICLs. However, the relationship between them in ICL repair and whether αIISp is involved in FANCD2's function in repair is unclear. The present studies show that, after ICL formation, FANCD2 disassociates from αIISp and localizes, before αIISp, at sites of damage in nuclear foci. αIISp and FANCD2 foci do not co-localize, in contrast to our previous finding that αIISp and the ICL repair protein, XPF, co-localize and follow a similar time course for formation. Knock-down of αIISp has no effect on monoubiquitination of FANCD2 (FANCD2-Ub) or its localization to chromatin or foci, though it leads to decreased ICL repair. Studies using cells from FA patients, defective in ICL repair and αIISp, have elucidated an important role for αIISp in the function of non-Ub FANCD2. In FA complementation group A (FA-A) cells, in which FANCD2 is not monoubiquitinated and does not form damage-induced foci, we demonstrate that restoration of αIISp levels to normal, by knocking down the protease μ-calpain, leads to formation of non-Ub FANCD2 foci after ICL damage. Since restoration of αIISp levels in FA-A cells restores DNA repair and cell survival, we propose that αIISp is critical for recruitment of non-Ub FANCD2 to sites of damage, which has an important role in the repair response and ICL repair.
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Affiliation(s)
- Pan Zhang
- Department of Pathology and Laboratory Medicine, Rutgers New Jersey Medical School, 185 South Orange Avenue, Newark, New Jersey, 07103, USA
| | - Deepa Sridharan
- Department of Pathology and Laboratory Medicine, Rutgers New Jersey Medical School, 185 South Orange Avenue, Newark, New Jersey, 07103, USA
| | - Muriel W Lambert
- Department of Pathology and Laboratory Medicine, Rutgers New Jersey Medical School, 185 South Orange Avenue, Newark, New Jersey, 07103, USA
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14
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Friboulet L, Postel-Vinay S, Sourisseau T, Adam J, Stoclin A, Ponsonnailles F, Dorvault N, Commo F, Saulnier P, Salome-Desmoulez S, Pottier G, André F, Kroemer G, Soria JC, Olaussen KA. ERCC1 function in nuclear excision and interstrand crosslink repair pathways is mediated exclusively by the ERCC1-202 isoform. Cell Cycle 2013; 12:3298-306. [PMID: 24036546 DOI: 10.4161/cc.26309] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
ERCC1 (excision repair cross-complementation group 1) plays essential roles in the removal of DNA intrastrand crosslinks by nucleotide excision repair, and that of DNA interstrand crosslinks by the Fanconi anemia (FA) pathway and homology-directed repair processes (HDR). The function of ERCC1 thus impacts on the DNA damage response (DDR), particularly in anticancer therapy when DNA damaging agents are employed. ERCC1 expression has been proposed as a predictive biomarker of the response to platinum-based therapy. However, the assessment of ERCC1 expression in clinical samples is complicated by the existence of 4 functionally distinct protein isoforms, which differently impact on DDR. Here, we explored the functional competence of each ERCC1 protein isoform and obtained evidence that the 202 isoform is the sole one endowed with ERCC1 activity in DNA repair pathways. The ERCC1 isoform 202 interacts with RPA, XPA, and XPF, and XPF stability requires expression of the ERCC1 202 isoform (but none of the 3 others). ERCC1-deficient non-small cell lung cancer cells show abnormal mitosis, a phenotype reminiscent of the FA phenotype that can be rescued by isoform 202 only. Finally, we could not observe any dominant-negative interaction between ERCC1 isoforms. These data suggest that the selective assessment of the ERCC1 isoform 202 in clinical samples should accurately reflect the DDR-related activity of the gene and hence constitute a useful biomarker for customizing anticancer therapies.
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Affiliation(s)
- Luc Friboulet
- Gustave Roussy; Villejuif, France; INSERM, U981; IRCIV; Villejuif, France; Département Hospitalo-Universitaire Thorax Innovation (DHU TORINO); Villejuif, France; Université Paris Sud; Kremlin-Bicêtre, France
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15
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McNeil EM, Melton DW. DNA repair endonuclease ERCC1-XPF as a novel therapeutic target to overcome chemoresistance in cancer therapy. Nucleic Acids Res 2012; 40:9990-10004. [PMID: 22941649 PMCID: PMC3488251 DOI: 10.1093/nar/gks818] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The ERCC1–XPF complex is a structure-specific endonuclease essential for the repair of DNA damage by the nucleotide excision repair pathway. It is also involved in other key cellular processes, including DNA interstrand crosslink (ICL) repair and DNA double-strand break (DSB) repair. New evidence has recently emerged, increasing our understanding of its requirement in these additional roles. In this review, we focus on the protein–protein and protein–DNA interactions made by the ERCC1 and XPF proteins and discuss how these coordinate ERCC1–XPF in its various roles. In a number of different cancers, high expression of ERCC1 has been linked to a poor response to platinum-based chemotherapy. We discuss prospects for the development of DNA repair inhibitors that target the activity, stability or protein interactions of the ERCC1–XPF complex as a novel therapeutic strategy to overcome chemoresistance.
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Affiliation(s)
- Ewan M McNeil
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK
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16
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Facista A, Nguyen H, Lewis C, Prasad AR, Ramsey L, Zaitlin B, Nfonsam V, Krouse RS, Bernstein H, Payne CM, Stern S, Oatman N, Banerjee B, Bernstein C. Deficient expression of DNA repair enzymes in early progression to sporadic colon cancer. Genome Integr 2012; 3:3. [PMID: 22494821 PMCID: PMC3351028 DOI: 10.1186/2041-9414-3-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2011] [Accepted: 04/11/2012] [Indexed: 12/11/2022] Open
Abstract
Background Cancers often arise within an area of cells (e.g. an epithelial patch) that is predisposed to the development of cancer, i.e. a "field of cancerization" or "field defect." Sporadic colon cancer is characterized by an elevated mutation rate and genomic instability. If a field defect were deficient in DNA repair, DNA damages would tend to escape repair and give rise to carcinogenic mutations. Purpose To determine whether reduced expression of DNA repair proteins Pms2, Ercc1 and Xpf (pairing partner of Ercc1) are early steps in progression to colon cancer. Results Tissue biopsies were taken during colonoscopies of 77 patients at 4 different risk levels for colon cancer, including 19 patients who had never had colonic neoplasia (who served as controls). In addition, 158 tissue samples were taken from tissues near or within colon cancers removed by resection and 16 tissue samples were taken near tubulovillous adenomas (TVAs) removed by resection. 568 triplicate tissue sections (a total of 1,704 tissue sections) from these tissue samples were evaluated by immunohistochemistry for 4 DNA repair proteins. Substantially reduced protein expression of Pms2, Ercc1 and Xpf occurred in field defects of up to 10 cm longitudinally distant from colon cancers or TVAs and within colon cancers. Expression of another DNA repair protein, Ku86, was infrequently reduced in these areas. When Pms2, Ercc1 or Xpf were reduced in protein expression, then either one or both of the other two proteins most often had reduced protein expression as well. The mean inner colon circumferences, from 32 resections, of the ascending, transverse and descending/sigmoid areas were measured as 6.6 cm, 5.8 cm and 6.3 cm, respectively. When combined with other measurements in the literature, this indicates the approximate mean number of colonic crypts in humans is 10 million. Conclusions The substantial deficiencies in protein expression of DNA repair proteins Pms2, Ercc1 and Xpf in about 1 million crypts near cancers and TVAs suggests that the tumors arose in field defects that were deficient in DNA repair and that deficiencies in Pms2, Ercc1 and Xpf are early steps, often occurring together, in progression to colon cancer.
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Affiliation(s)
- Alexander Facista
- Southern Arizona Veterans Affairs Heath Care System, Mail Stop 0-151, 3601 S, 6th Ave,, Tucson, Arizona 85723, USA.
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Krenzlin H, Demuth I, Salewsky B, Wessendorf P, Weidele K, Bürkle A, Digweed M. DNA damage in Nijmegen Breakage Syndrome cells leads to PARP hyperactivation and increased oxidative stress. PLoS Genet 2012; 8:e1002557. [PMID: 22396666 PMCID: PMC3291567 DOI: 10.1371/journal.pgen.1002557] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 01/11/2012] [Indexed: 11/18/2022] Open
Abstract
Nijmegen Breakage Syndrome (NBS), an autosomal recessive genetic instability syndrome, is caused by hypomorphic mutation of the NBN gene, which codes for the protein nibrin. Nibrin is an integral member of the MRE11/RAD50/NBN (MRN) complex essential for processing DNA double-strand breaks. Cardinal features of NBS are immunodeficiency and an extremely high incidence of hematological malignancies. Recent studies in conditional null mutant mice have indicated disturbances in redox homeostasis due to impaired DSB processing. Clearly this could contribute to DNA damage, chromosomal instability, and cancer occurrence. Here we show, in the complete absence of nibrin in null mutant mouse cells, high levels of reactive oxygen species several hours after exposure to a mutagen. We show further that NBS patient cells, which unlike mouse null mutant cells have a truncated nibrin protein, also have high levels of reactive oxygen after DNA damage and that this increased oxidative stress is caused by depletion of NAD+ due to hyperactivation of the strand-break sensor, Poly(ADP-ribose) polymerase. Both hyperactivation of Poly(ADP-ribose) polymerase and increased ROS levels were reversed by use of a specific Poly(ADP-ribose) polymerase inhibitor. The extremely high incidence of malignancy among NBS patients is the result of the combination of a primary DSB repair deficiency with secondary oxidative DNA damage. Damage to DNA is extremely dangerous because it can lead to mutations in genes that initiate or accelerate the development of a tumor. Evolution has led to highly complex networks of DNA repair enzymes, which for the majority of individuals are extremely effective in keeping our DNA intact. The devastating consequences of DNA damage are manifested in those individuals in which one or other of the repair pathways is non-functional. Several genetic disorders can be attributed to such DNA repair deficiencies and have the common feature of increased tumor incidence as the major life-threatening symptom. Cancer incidence varies amongst these disorders and is probably highest for the disease Nijmegen Breakage Syndrome, where more than 50% of patients develop a hematological malignancy in childhood. We have sought to understand this extremely high incidence by exploiting cells from a mouse model and cells derived from patients. We find that deficiency in the repair of DNA double-strand breaks leads to disturbances in cellular metabolism, leading ultimately to a loss of antioxidative capacity. The ensuing accumulation of highly reactive oxygen species generates further DNA lesions, thus potentiating the initial damage and increasing the likelihood of malignancy.
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Affiliation(s)
- Harald Krenzlin
- Institute of Medical and Human Genetics, Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Ilja Demuth
- Institute of Medical and Human Genetics, Charité – Universitätsmedizin Berlin, Berlin, Germany
- The Berlin Aging Study II, Research Group on Geriatrics, Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Bastian Salewsky
- Institute of Medical and Human Genetics, Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Petra Wessendorf
- Institute of Medical and Human Genetics, Charité – Universitätsmedizin Berlin, Berlin, Germany
| | - Kathrin Weidele
- Molecular Toxicology, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Alexander Bürkle
- Molecular Toxicology, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Martin Digweed
- Institute of Medical and Human Genetics, Charité – Universitätsmedizin Berlin, Berlin, Germany
- * E-mail:
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18
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Deakyne JS, Mazin AV. Fanconi anemia: at the crossroads of DNA repair. BIOCHEMISTRY (MOSCOW) 2011; 76:36-48. [PMID: 21568838 DOI: 10.1134/s0006297911010068] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Fanconi anemia (FA) is an autosomal disorder that causes genome instability. FA patients suffer developmental abnormalities, early-onset bone marrow failure, and a predisposition to cancer. The disease is manifested by defects in DNA repair, hypersensitivity to DNA crosslinking agents, and a high degree of chromosomal aberrations. The FA pathway comprises 13 disease-causing genes involved in maintaining genomic stability. The fast pace of study of the novel DNA damage network has led to the constant discovery of new FA-like genes involved in the pathway that when mutated lead to similar disorders. A majority of the FA proteins act as signal transducers and scaffolding proteins to employ other pathways to repair DNA. This review discusses what is known about the FA proteins and other recently linked FA-like proteins. The goal is to clarify how the proteins work together to carry out interstrand crosslink repair and homologous recombination-mediated repair of damaged DNA.
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Affiliation(s)
- J S Deakyne
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, USA
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19
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Machnicka B, Grochowalska R, Bogusławska DM, Sikorski AF, Lecomte MC. Spectrin-based skeleton as an actor in cell signaling. Cell Mol Life Sci 2011; 69:191-201. [PMID: 21877118 PMCID: PMC3249148 DOI: 10.1007/s00018-011-0804-5] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 08/08/2011] [Accepted: 08/10/2011] [Indexed: 01/12/2023]
Abstract
This review focuses on the recent advances in functions of spectrins in non-erythroid cells. We discuss new data concerning the commonly known role of the spectrin-based skeleton in control of membrane organization, stability and shape, and tethering protein mosaics to the cellular motors and to all major filament systems. Particular effort has been undertaken to highlight recent advances linking spectrin to cell signaling phenomena and its participation in signal transduction pathways in many cell types.
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Affiliation(s)
- B Machnicka
- University of Zielona Góra, Zielona Góra, Poland
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Zhang P, Sridharan D, Lambert MW. Knockdown of mu-calpain in Fanconi anemia, FA-A, cells by siRNA restores alphaII spectrin levels and corrects chromosomal instability and defective DNA interstrand cross-link repair. Biochemistry 2010; 49:5570-81. [PMID: 20518497 DOI: 10.1021/bi100656j] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We have previously shown that there is a deficiency in the structural protein, nonerythroid alpha spectrin (alphaIISp), in cells from patients with Fanconi anemia (FA). These studies indicate that this deficiency is due to the reduced stability of alphaIISp and correlates with a decreased level of repair of DNA interstrand cross-links and chromosomal instability in FA cells. An important factor in the stability of alphaIISp is its susceptibility to cleavage by the protease, mu-calpain. We hypothesized that an increased level of mu-calpain cleavage of alphaIISp in FA cells leads to an increased level of breakdown of alphaIISp and that knocking down expression of mu-calpain in FA cells should restore levels of alphaIISp and correct a number of the phenotypic defects observed. The results showed that there is increased mu-calpain activity in FA-A, FA-C, FA-D2, FA-F, and FA-G cells that could account for the deficiency in alphaIISp in these FA cells. Protein interaction studies indicated that FANCA and FANCG bind directly to mu-calpain. We hypothesize that this binding may lead to inhibition of mu-calpain activity in normal cells. Knocking down mu-calpain by siRNA in FA-A cells restored levels of alphaIISp to normal and reversed a number of the cellular deficiencies in these cells. It corrected the DNA repair defect and the chromosomal instability observed after exposure to a DNA interstrand cross-linking agent. These studies indicate that FA proteins may play an important role in maintaining the stability of alphaIISp in the cell by regulating its cleavage by mu-calpain. Thus, by reducing the level of breakdown of alphaIISp in FA cells, we may be able to reverse a number of the cellular deficiencies observed in this disorder.
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Affiliation(s)
- Pan Zhang
- Department of Pathology and Laboratory Medicine, New Jersey Medical School and Graduate School of Biomedical Sciences, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103, USA
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