1
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Mahdouani M, Zhuri D, Sezginer Guler H, Hmida D, Sana M, Azaza M, Ben Said M, Masmoudi S, Hmila F, Youssef S, Ben Sghaier R, Brieger A, Zeuzem S, Saad A, Gurkan H, Yalcintepe S, Gribaa M, Plotz G. Functional analysis of MMR gene VUS from potential Lynch syndrome patients. PLoS One 2024; 19:e0304141. [PMID: 38843250 PMCID: PMC11156341 DOI: 10.1371/journal.pone.0304141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 05/06/2024] [Indexed: 06/09/2024] Open
Abstract
Lynch syndrome is caused by inactivating variants in DNA mismatch repair genes, namely MLH1, MSH2, MSH6 and PMS2. We have investigated five MLH1 and one MSH2 variants that we have identified in Turkish and Tunisian colorectal cancer patients. These variants comprised two small deletions causing frameshifts resulting in premature stops which could be classified pathogenic (MLH1 p.(His727Profs*57) and MSH2 p.(Thr788Asnfs*11)), but also two missense variants (MLH1 p.(Asn338Ser) and p.(Gly181Ser)) and two small, in-frame deletion variants (p.(Val647-Leu650del) and p.(Lys678_Cys680del)). For such small coding genetic variants, it is unclear if they are inactivating or not. We here provide clinical description of the variant carriers and their families, and we performed biochemical laboratory testing on the variant proteins to test if their stability or their MMR activity are compromised. Subsequently, we compared the results to in-silico predictions on structure and conservation. We demonstrate that neither missense alteration affected function, while both deletion variants caused a dramatic instability of the MLH1 protein, resulting in MMR deficiency. These results were consistent with the structural analyses that were performed. The study shows that knowledge of protein function may provide molecular explanations of results obtained with functional biochemical testing and can thereby, in conjunction with clinical information, elevate the evidential value and facilitate clinical management in affected families.
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Affiliation(s)
- Marwa Mahdouani
- Laboratory of Cytogenetics, Molecular Genetics and Human Reproduction Biology, Farhat Hached University Hospital, Sousse, Tunisia
- Higher Institute of Biotechnology of Monastir, University of Monastir, Monastir, Tunisia
| | - Drenushe Zhuri
- Department of Medical Genetics, Trakya University School of Medicine, Edirne, Turkey
| | - Hazal Sezginer Guler
- Department of Medical Genetics, Trakya University School of Medicine, Edirne, Turkey
| | - Dorra Hmida
- Laboratory of Cytogenetics, Molecular Genetics and Human Reproduction Biology, Farhat Hached University Hospital, Sousse, Tunisia
- Faculty of Medicine Ibn El Jazzar of Sousse, University of Sousse, Sousse, Tunisia
| | - Mokni Sana
- Faculty of Medicine Ibn El Jazzar of Sousse, University of Sousse, Sousse, Tunisia
- Department of Dermatology and Venerology, Farhat Hached University Hospital, Sousse, Tunisia
| | - Mohamed Azaza
- Department of General Surgery, Sahloul University Hospital, Sousse, Tunisia
| | - Mariem Ben Said
- Laboratory of Molecular and Cellular Screening Processes, Center of Biotechnology of Sfax, Sfax, Tunisia
| | - Saber Masmoudi
- Laboratory of Molecular and Cellular Screening Processes, Center of Biotechnology of Sfax, Sfax, Tunisia
| | - Fahmi Hmila
- Faculty of Medicine Ibn El Jazzar of Sousse, University of Sousse, Sousse, Tunisia
- Department of General and Digestive Surgery, Farhat Hached University Hospital, Sousse, Tunisia
| | - Sabri Youssef
- Department of General Surgery, Farhat Hached University Hospital, Sousse, Tunisia
| | - Rihab Ben Sghaier
- Laboratory of Cytogenetics, Molecular Genetics and Human Reproduction Biology, Farhat Hached University Hospital, Sousse, Tunisia
- Higher Institute of Biotechnology of Monastir, University of Monastir, Monastir, Tunisia
| | - Angela Brieger
- Biomedical Research Laboratory, Medical Clinic 1, University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Stefan Zeuzem
- Biomedical Research Laboratory, Medical Clinic 1, University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Ali Saad
- Laboratory of Cytogenetics, Molecular Genetics and Human Reproduction Biology, Farhat Hached University Hospital, Sousse, Tunisia
- Faculty of Medicine Ibn El Jazzar of Sousse, University of Sousse, Sousse, Tunisia
| | - Hakan Gurkan
- Department of Medical Genetics, Trakya University School of Medicine, Edirne, Turkey
| | - Sinem Yalcintepe
- Department of Medical Genetics, Trakya University School of Medicine, Edirne, Turkey
| | - Moez Gribaa
- Laboratory of Cytogenetics, Molecular Genetics and Human Reproduction Biology, Farhat Hached University Hospital, Sousse, Tunisia
- Faculty of Medicine Ibn El Jazzar of Sousse, University of Sousse, Sousse, Tunisia
| | - Guido Plotz
- Biomedical Research Laboratory, Medical Clinic 1, University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany
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Wolf K, Kosinski J, Gibson TJ, Wesch N, Dötsch V, Genuardi M, Cordisco EL, Zeuzem S, Brieger A, Plotz G. A conserved motif in the disordered linker of human MLH1 is vital for DNA mismatch repair and its function is diminished by a cancer family mutation. Nucleic Acids Res 2023; 51:6307-6320. [PMID: 37224528 PMCID: PMC10325900 DOI: 10.1093/nar/gkad418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 04/26/2023] [Accepted: 05/17/2023] [Indexed: 05/26/2023] Open
Abstract
DNA mismatch repair (MMR) is essential for correction of DNA replication errors. Germline mutations of the human MMR gene MLH1 are the major cause of Lynch syndrome, a heritable cancer predisposition. In the MLH1 protein, a non-conserved, intrinsically disordered region connects two conserved, catalytically active structured domains of MLH1. This region has as yet been regarded as a flexible spacer, and missense alterations in this region have been considered non-pathogenic. However, we have identified and investigated a small motif (ConMot) in this linker which is conserved in eukaryotes. Deletion of the ConMot or scrambling of the motif abolished mismatch repair activity. A mutation from a cancer family within the motif (p.Arg385Pro) also inactivated MMR, suggesting that ConMot alterations can be causative for Lynch syndrome. Intriguingly, the mismatch repair defect of the ConMot variants could be restored by addition of a ConMot peptide containing the deleted sequence. This is the first instance of a DNA mismatch repair defect conferred by a mutation that can be overcome by addition of a small molecule. Based on the experimental data and AlphaFold2 predictions, we suggest that the ConMot may bind close to the C-terminal MLH1-PMS2 endonuclease and modulate its activation during the MMR process.
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Affiliation(s)
- Karla Wolf
- Department of Internal Medicine 1, University Hospital, Goethe University, Frankfurt am Main, 60590, Germany
| | - Jan Kosinski
- European Molecular Biology Laboratory (EMBL), Centre for Structural Systems Biology (CSSB), Hamburg, 22607, Germany
| | - Toby J Gibson
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Heidelberg, 69117, Germany
| | - Nicole Wesch
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt am Main, 60438, Germany
| | - Volker Dötsch
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Frankfurt am Main, 60438, Germany
| | - Maurizio Genuardi
- UOC Genetica Medica, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome00168, Italy
| | - Emanuela Lucci Cordisco
- Dipartimento di Scienze della Vita e di Sanità Pubblica, Università Cattolica del Sacro Cuore, Rome00168, Italy
| | - Stefan Zeuzem
- Department of Internal Medicine 1, University Hospital, Goethe University, Frankfurt am Main, 60590, Germany
| | - Angela Brieger
- Department of Internal Medicine 1, University Hospital, Goethe University, Frankfurt am Main, 60590, Germany
| | - Guido Plotz
- Department of Internal Medicine 1, University Hospital, Goethe University, Frankfurt am Main, 60590, Germany
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3
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Mahdouani M, Ben Ahmed S, Hmila F, Rais H, Ben Sghaier R, Saad H, Ben Said M, Masmoudi S, Hmida D, Brieger A, Zeuzem S, Saad A, Gribaa M, Plotz G. Functional characterization of MLH1 missense variants unveils mechanisms of pathogenicity and clarifies role in cancer. PLoS One 2022; 17:e0278283. [PMID: 36454741 PMCID: PMC9714755 DOI: 10.1371/journal.pone.0278283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 10/28/2022] [Indexed: 12/05/2022] Open
Abstract
Lynch syndrome is a heritable condition caused by a heterozygous germline inactivating mutation of the DNA mismatch repair (MMR) genes, most commonly the MLH1 gene. However, one third of the identified alterations are missense variants, for which the clinical significance is unclear in many cases. We have identified three MLH1 missense alterations (p.(Glu736Lys), p.(Pro640Thr) and p.(Leu73Pro)) in six individuals from large Tunisian families. For none of these alterations, a classification of pathogenicity was available, consequently diagnosis, predictive testing and targeted surveillance in affected families was impossible. We therefore performed functional laboratory testing using a system testing stability as well as catalytic activity that includes clinically validated reference variants. Both p.(Leu73Pro) and p.(Pro640Thr) were found to be non-functional due to severe defects in protein stability and catalytic activity. In contrast, p.(Glu736Lys) was comparable to the wildtype protein and therefore considered a neutral substitution. Analysis of residue conservation and of the structural roles of the substituted residues corroborated these findings. In conjunction with the available clinical data, two variants fulfil classification criteria for class 4 "likely pathogenic". The findings of this work clarify the mechanism of pathogenicity of two unclear MLH1 variants and enables predictive testing and targeted surveillance in members of carrier families worldwide.
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Affiliation(s)
- Marwa Mahdouani
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, Tunisia
- Higher Institute of Biotechnology of Monastir, University of Monastir, Monastir, Tunisia
| | - Slim Ben Ahmed
- Department of Oncology, Farhat Hached University Hospital, Sousse, Tunisia
- Faculty of Medicine Ibn El Jazzar of Sousse, University of Sousse, Sousse, Tunisia
| | - Fahmi Hmila
- Faculty of Medicine Ibn El Jazzar of Sousse, University of Sousse, Sousse, Tunisia
- Department of General and Digestive Surgery, Farhat Hached University Hospital, Sousse, Tunisia
| | - Henda Rais
- Medical Service, Salah Azaiez Institute, Tunis, Tunisia
| | - Rihab Ben Sghaier
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, Tunisia
- Higher Institute of Biotechnology of Monastir, University of Monastir, Monastir, Tunisia
| | - Hanene Saad
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, Tunisia
- Higher Institute of Biotechnology of Monastir, University of Monastir, Monastir, Tunisia
| | - Mariem Ben Said
- Laboratory of Molecular and Cellular Screening Processes, Centre of Biotechnology of Sfax, Sfax, Tunisia
| | - Saber Masmoudi
- Laboratory of Molecular and Cellular Screening Processes, Centre of Biotechnology of Sfax, Sfax, Tunisia
| | - Dorra Hmida
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, Tunisia
- Faculty of Medicine Ibn El Jazzar of Sousse, University of Sousse, Sousse, Tunisia
| | - Angela Brieger
- Biomedical Research Laboratory, Department of Internal Medicine 1, University Hospital, Goethe University, Frankfurt am Main, Germany
| | - Stefan Zeuzem
- Biomedical Research Laboratory, Department of Internal Medicine 1, University Hospital, Goethe University, Frankfurt am Main, Germany
| | - Ali Saad
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, Tunisia
- Faculty of Medicine Ibn El Jazzar of Sousse, University of Sousse, Sousse, Tunisia
| | - Moez Gribaa
- Laboratory of Human Cytogenetics, Molecular Genetics and Reproductive Biology, Farhat Hached University Hospital, Sousse, Tunisia
- Faculty of Medicine Ibn El Jazzar of Sousse, University of Sousse, Sousse, Tunisia
| | - Guido Plotz
- Biomedical Research Laboratory, Department of Internal Medicine 1, University Hospital, Goethe University, Frankfurt am Main, Germany
- * E-mail:
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4
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González-Acosta M, Hinrichsen I, Fernández A, Lázaro C, Pineda M, Plotz G, Capellá G. Validation of an in Vitro Mismatch Repair Assay Used in the Functional Characterization of Mismatch Repair Variants. J Mol Diagn 2019; 22:376-385. [PMID: 31881334 DOI: 10.1016/j.jmoldx.2019.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 09/27/2019] [Accepted: 12/05/2019] [Indexed: 10/25/2022] Open
Abstract
A significant proportion of DNA-mismatch repair (MMR) variants are classified as of unknown significance, precluding diagnosis. The in vitro MMR assay is used to assess their MMR capability, likely the most important function of an MMR protein. However, the robustness of the assay, crucial for its use in the clinical setting, has been rarely evaluated. The aim of the present work was to validate an in vitro MMR assay approach to the functional characterization of MMR variants, as a first step to meeting quality standards of diagnostic laboratories. The MMR assay was optimized by testing a variety of reagents and experimental conditions. Reference materials and standard operating procedures were established. To determine the intra- and interexperimental variability of the assay and its reproducibility among centers, independent transfections of six previously characterized MLH1 variants were performed in two independent laboratories. Reagents and conditions optimal for performing the in vitro MMR assay were determined. The validated assay demonstrated no significant intra- or interexperimental variability and good reproducibility between centers. We set up a robust in vitro MMR assay that can provide relevant in vitro functional evidence for MMR variant pathogenicity assessment, eventually improving the molecular diagnosis of hereditary cancer syndromes associated with MMR deficiency.
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Affiliation(s)
- Maribel González-Acosta
- Hereditary Cancer Program, the Catalan Institute of Oncology (ICO), Hereditary Cancer Group, Molecular Mechanisms and Experimental Therapy in Oncology Program, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Ciber Oncología (CIBERONC) Instituto Salud Carlos III, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Inga Hinrichsen
- Biomedical Research Laboratory, Department of Internal Medicine 1, Universitätsklinikum Frankfurt, Frankfurt, Germany
| | - Anna Fernández
- Hereditary Cancer Program, the Catalan Institute of Oncology (ICO), Hereditary Cancer Group, Molecular Mechanisms and Experimental Therapy in Oncology Program, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Ciber Oncología (CIBERONC) Instituto Salud Carlos III, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Conxi Lázaro
- Hereditary Cancer Program, the Catalan Institute of Oncology (ICO), Hereditary Cancer Group, Molecular Mechanisms and Experimental Therapy in Oncology Program, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Ciber Oncología (CIBERONC) Instituto Salud Carlos III, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Marta Pineda
- Hereditary Cancer Program, the Catalan Institute of Oncology (ICO), Hereditary Cancer Group, Molecular Mechanisms and Experimental Therapy in Oncology Program, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Ciber Oncología (CIBERONC) Instituto Salud Carlos III, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Guido Plotz
- Biomedical Research Laboratory, Department of Internal Medicine 1, Universitätsklinikum Frankfurt, Frankfurt, Germany
| | - Gabriel Capellá
- Hereditary Cancer Program, the Catalan Institute of Oncology (ICO), Hereditary Cancer Group, Molecular Mechanisms and Experimental Therapy in Oncology Program, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Ciber Oncología (CIBERONC) Instituto Salud Carlos III, L'Hospitalet de Llobregat, Barcelona, Spain.
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5
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Bonjoch L, Mur P, Arnau-Collell C, Vargas-Parra G, Shamloo B, Franch-Expósito S, Pineda M, Capellà G, Erman B, Castellví-Bel S. Approaches to functionally validate candidate genetic variants involved in colorectal cancer predisposition. Mol Aspects Med 2019; 69:27-40. [PMID: 30935834 DOI: 10.1016/j.mam.2019.03.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 03/26/2019] [Accepted: 03/26/2019] [Indexed: 02/07/2023]
Abstract
Most next generation sequencing (NGS) studies identified candidate genetic variants predisposing to colorectal cancer (CRC) but do not tackle its functional interpretation to unequivocally recognize a new hereditary CRC gene. Besides, germline variants in already established hereditary CRC-predisposing genes or somatic variants share the same need when trying to categorize those with relevant significance. Functional genomics approaches have an important role in identifying the causal links between genetic architecture and phenotypes, in order to decipher cellular function in health and disease. Therefore, functional interpretation of identified genetic variants by NGS platforms is now essential. Available approaches nowadays include bioinformatics, cell and molecular biology and animal models. Recent advances, such as the CRISPR-Cas9, ZFN and TALEN systems, have been already used as a powerful tool with this objective. However, the use of cell lines is of limited value due to the CRC heterogeneity and its close interaction with microenvironment. Access to tridimensional cultures or organoids and xenograft models that mimic the in vivo tissue architecture could revolutionize functional analysis. This review will focus on the application of state-of-the-art functional studies to better tackle new genes involved in germline predisposition to this neoplasm.
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Affiliation(s)
- Laia Bonjoch
- Gastroenterology Department, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), University of Barcelona, Barcelona, Spain
| | - Pilar Mur
- Hereditary Cancer Program, Catalan Institute of Oncology, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), ONCOBELL Program, L'Hospitalet de Llobregat, Barcelona, Spain; Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Spain
| | - Coral Arnau-Collell
- Gastroenterology Department, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), University of Barcelona, Barcelona, Spain
| | - Gardenia Vargas-Parra
- Hereditary Cancer Program, Catalan Institute of Oncology, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), ONCOBELL Program, L'Hospitalet de Llobregat, Barcelona, Spain; Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Spain
| | - Bahar Shamloo
- Molecular Biology, Genetics, and Bioengineering Department, Legacy Research Institute, Portland, OR, USA
| | - Sebastià Franch-Expósito
- Gastroenterology Department, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), University of Barcelona, Barcelona, Spain
| | - Marta Pineda
- Hereditary Cancer Program, Catalan Institute of Oncology, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), ONCOBELL Program, L'Hospitalet de Llobregat, Barcelona, Spain; Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Spain
| | - Gabriel Capellà
- Hereditary Cancer Program, Catalan Institute of Oncology, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), ONCOBELL Program, L'Hospitalet de Llobregat, Barcelona, Spain; Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Spain
| | - Batu Erman
- Molecular Biology, Genetics and Bioengineering Program, Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey
| | - Sergi Castellví-Bel
- Gastroenterology Department, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), University of Barcelona, Barcelona, Spain.
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6
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D'Arcy BM, Blount J, Prakash A. Biochemical and structural characterization of two variants of uncertain significance in the PMS2 gene. Hum Mutat 2019; 40:458-471. [PMID: 30653781 DOI: 10.1002/humu.23708] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 12/28/2018] [Accepted: 01/14/2019] [Indexed: 12/16/2022]
Abstract
Lynch syndrome (LS) is an autosomal dominant inherited disorder that is associated with an increased predisposition to certain cancers caused by loss-of-function mutations in one of four DNA mismatch repair (MMR) genes (MLH1, MSH2, MSH6, or PMS2). The diagnosis of LS is often challenged by the identification of missense mutations where the functional effects are not known. These are termed variants of uncertain significance (VUSs) and account for 20%-30% of noncoding and missense mutations. VUSs cause ambiguity during clinical diagnosis and hinder implementation of appropriate medical management. In the current study, we focus on the functional and biological consequences of two nonsynonymous VUSs in PMS2. These variants, c.620G>A and c.123_131delGTTAGTAGA, result in the alteration of glycine 207 to glutamate (p.Gly207Glu) and the deletion of amino acid residues 42-44 (p.Leu42_Glu44del), respectively. While the PMS2 p.Gly207Glu variant retains in vitro MMR and ATPase activities, PMS2 p.Leu42_Glu44del appears to lack such capabilities. Structural and biophysical characterization using circular dichroism, small-angle X-ray scattering, and X-ray crystallography of the N-terminal domain of the PMS2 variants indicate that the p.Gly207Glu variant is properly folded similar to the wild-type enzyme, whereas p.Leu42_Glu44del is disordered and prone to aggregation.
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Affiliation(s)
- Brandon M D'Arcy
- Mitchell Cancer Institute, The University of South Alabama, Mobile, Alabama
| | - Jessa Blount
- Mitchell Cancer Institute, The University of South Alabama, Mobile, Alabama
| | - Aishwarya Prakash
- Mitchell Cancer Institute, The University of South Alabama, Mobile, Alabama
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7
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Weßbecher IM, Hinrichsen I, Funke S, Oellerich T, Plotz G, Zeuzem S, Grus FH, Biondi RM, Brieger A. DNA mismatch repair activity of MutLα is regulated by CK2-dependent phosphorylation of MLH1 (S477). Mol Carcinog 2018; 57:1723-1734. [DOI: 10.1002/mc.22892] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 06/22/2018] [Accepted: 08/18/2018] [Indexed: 12/15/2022]
Affiliation(s)
- Isabel M. Weßbecher
- Medical Clinic I; Biomedical Research Laboratory; Goethe-University; Frankfurt Germany
| | - Inga Hinrichsen
- Medical Clinic I; Biomedical Research Laboratory; Goethe-University; Frankfurt Germany
| | - Sebastian Funke
- Department of Ophthalmology; Experimental Ophthalmology; University Medical Center; Gutenberg University; Mainz Germany
| | - Thomas Oellerich
- Department of Medicine II, Hematology/Oncology; Goethe-University; Frankfurt Germany
| | - Guido Plotz
- Medical Clinic I; Biomedical Research Laboratory; Goethe-University; Frankfurt Germany
| | - Stefan Zeuzem
- Medical Clinic I; Biomedical Research Laboratory; Goethe-University; Frankfurt Germany
| | - Franz H. Grus
- Department of Ophthalmology; Experimental Ophthalmology; University Medical Center; Gutenberg University; Mainz Germany
| | - Ricardo M. Biondi
- Medical Clinic I; Biomedical Research Laboratory; Goethe-University; Frankfurt Germany
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)-CONICET-Partner Institute of the Max Planck Society; Buenos Aires Argentina
| | - Angela Brieger
- Medical Clinic I; Biomedical Research Laboratory; Goethe-University; Frankfurt Germany
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8
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Köger N, Paulsen L, López-Kostner F, Della Valle A, Vaccaro CA, Palmero EI, Alvarez K, Sarroca C, Neffa F, Kalfayan PG, Gonzalez ML, Rossi BM, Reis RM, Brieger A, Zeuzem S, Hinrichsen I, Dominguez-Valentin M, Plotz G. Evaluation of MLH1 variants of unclear significance. Genes Chromosomes Cancer 2018. [PMID: 29520894 DOI: 10.1002/gcc.22536] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Inactivating mutations in the MLH1 gene cause the cancer predisposition Lynch syndrome, but for small coding genetic variants it is mostly unclear if they are inactivating or not. Nine such MLH1 variants have been identified in South American colorectal cancer (CRC) patients (p.Tyr97Asp, p.His112Gln, p.Pro141Ala, p.Arg265Pro, p.Asn338Ser, p.Ile501del, p.Arg575Lys, p.Lys618del, p.Leu676Pro), and evidence of pathogenicity or neutrality was not available for the majority of these variants. We therefore performed biochemical laboratory testing of the variant proteins and compared the results to protein in silico predictions on structure and conservation. Additionally, we collected all available clinical information of the families to come to a conclusion concerning their pathogenic potential and facilitate clinical diagnosis in the affected families. We provide evidence that four of the alterations are causative for Lynch syndrome, four are likely neutral and one shows compromised activity which can currently not be classified with respect to its pathogenic potential. The work demonstrates that biochemical testing, corroborated by congruent evolutionary and structural information, can serve to reliably classify uncertain variants when other data are insufficient.
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Affiliation(s)
- Nicole Köger
- Biomedizinisches Forschungslabor, Medizinische Klinik 1, Universitätsklinik Frankfurt, Frankfurt, Germany
| | - Lea Paulsen
- Biomedizinisches Forschungslabor, Medizinische Klinik 1, Universitätsklinik Frankfurt, Frankfurt, Germany
| | | | - Adriana Della Valle
- Hospital Fuerzas Armadas, Grupo Colaborativo Uruguayo, Investigación de Afecciones Oncológicas Hereditarias (GCU), Montevideo, Uruguay
| | | | - Edenir Inêz Palmero
- Barretos Cancer Hospital, Molecular Oncology Research Center, Barretos, São Paulo, Brazil.,Barretos School of Health Sciences-FACISB, Barretos, São Paulo, Brazil
| | - Karin Alvarez
- Laboratorio de Oncología y Genética Molecular, Clínica Los Condes, Santiago, Chile
| | - Carlos Sarroca
- Hospital Fuerzas Armadas, Grupo Colaborativo Uruguayo, Investigación de Afecciones Oncológicas Hereditarias (GCU), Montevideo, Uruguay
| | - Florencia Neffa
- Hospital Fuerzas Armadas, Grupo Colaborativo Uruguayo, Investigación de Afecciones Oncológicas Hereditarias (GCU), Montevideo, Uruguay
| | | | - Maria Laura Gonzalez
- Hereditary Cancer Program (PROCANHE), Hospital Italiano, Buenos Aires, Argentina
| | | | - Rui Manuel Reis
- Biomedizinisches Forschungslabor, Medizinische Klinik 1, Universitätsklinik Frankfurt, Frankfurt, Germany.,Life and Health Sciences Q5 753 Research Institute (ICVS), Health Sciences School, University of Minho, Braga, 754, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga, Guimarães, 755, Portugal
| | - Angela Brieger
- Biomedizinisches Forschungslabor, Medizinische Klinik 1, Universitätsklinik Frankfurt, Frankfurt, Germany
| | - Stefan Zeuzem
- Biomedizinisches Forschungslabor, Medizinische Klinik 1, Universitätsklinik Frankfurt, Frankfurt, Germany
| | - Inga Hinrichsen
- Biomedizinisches Forschungslabor, Medizinische Klinik 1, Universitätsklinik Frankfurt, Frankfurt, Germany
| | - Mev Dominguez-Valentin
- Department of Tumor Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Guido Plotz
- Biomedizinisches Forschungslabor, Medizinische Klinik 1, Universitätsklinik Frankfurt, Frankfurt, Germany
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Peña-Diaz J, Rasmussen LJ. Approaches to diagnose DNA mismatch repair gene defects in cancer. DNA Repair (Amst) 2015; 38:147-154. [PMID: 26708048 DOI: 10.1016/j.dnarep.2015.11.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 08/12/2015] [Accepted: 11/30/2015] [Indexed: 12/12/2022]
Abstract
The DNA repair pathway mismatch repair (MMR) is responsible for the recognition and correction of DNA biosynthetic errors caused by inaccurate nucleotide incorporation during replication. Faulty MMR leads to failure to address the mispairs or insertion deletion loops (IDLs) left behind by the replicative polymerases and results in increased mutation load at the genome. The realization that defective MMR leads to a hypermutation phenotype and increased risk of tumorigenesis highlights the relevance of this pathway for human disease. The association of MMR defects with increased risk of cancer development was first observed in colorectal cancer patients that carried inactivating germline mutations in MMR genes and the disease was named as hereditary non-polyposis colorectal cancer (HNPCC). Currently, a growing list of cancers is found to be MMR defective and HNPCC has been renamed Lynch syndrome (LS) partly to include the associated risk of developing extra-colonic cancers. In addition, a number of non-hereditary, mostly epigenetic, alterations of MMR genes have been described in sporadic tumors. Besides conferring a strong cancer predisposition, genetic or epigenetic inactivation of MMR genes also renders cells resistant to some chemotherapeutic agents. Therefore, diagnosis of MMR deficiency has important implications for the management of the patients, the surveillance of their relatives in the case of LS and for the choice of treatment. Some of the alterations found in MMR genes have already been well defined and their pathogenicity assessed. Despite this substantial wealth of knowledge, the effects of a large number of alterations remain uncharacterized (variants of uncertain significance, VUSs). The advent of personalized genomics is likely to increase the list of VUSs found in MMR genes and anticipates the need of diagnostic tools for rapid assessment of their pathogenicity. This review describes current tools and future strategies for addressing the relevance of MMR gene alterations in human disease.
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Affiliation(s)
- Javier Peña-Diaz
- Center for Healthy Aging, Department of Neuroscience and Pharmacology, University of Copenhagen, DK-2200 Copenhagen, Denmark.
| | - Lene Juel Rasmussen
- Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, DK-2200 Copenhagen, Denmark.
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