1
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Kock KH, Kimes PK, Gisselbrecht SS, Inukai S, Phanor SK, Anderson JT, Ramakrishnan G, Lipper CH, Song D, Kurland JV, Rogers JM, Jeong R, Blacklow SC, Irizarry RA, Bulyk ML. DNA binding analysis of rare variants in homeodomains reveals homeodomain specificity-determining residues. Nat Commun 2024; 15:3110. [PMID: 38600112 PMCID: PMC11006913 DOI: 10.1038/s41467-024-47396-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 03/29/2024] [Indexed: 04/12/2024] Open
Abstract
Homeodomains (HDs) are the second largest class of DNA binding domains (DBDs) among eukaryotic sequence-specific transcription factors (TFs) and are the TF structural class with the largest number of disease-associated mutations in the Human Gene Mutation Database (HGMD). Despite numerous structural studies and large-scale analyses of HD DNA binding specificity, HD-DNA recognition is still not fully understood. Here, we analyze 92 human HD mutants, including disease-associated variants and variants of uncertain significance (VUS), for their effects on DNA binding activity. Many of the variants alter DNA binding affinity and/or specificity. Detailed biochemical analysis and structural modeling identifies 14 previously unknown specificity-determining positions, 5 of which do not contact DNA. The same missense substitution at analogous positions within different HDs often exhibits different effects on DNA binding activity. Variant effect prediction tools perform moderately well in distinguishing variants with altered DNA binding affinity, but poorly in identifying those with altered binding specificity. Our results highlight the need for biochemical assays of TF coding variants and prioritize dozens of variants for further investigations into their pathogenicity and the development of clinical diagnostics and precision therapies.
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Affiliation(s)
- Kian Hong Kock
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
- Program in Biological and Biomedical Sciences, Harvard University, Cambridge, MA, USA
| | - Patrick K Kimes
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Stephen S Gisselbrecht
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
| | - Sachi Inukai
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
| | - Sabrina K Phanor
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
| | - James T Anderson
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
| | - Gayatri Ramakrishnan
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
- Boston Bangalore Biosciences Beginnings Program, Harvard University, Cambridge, MA, USA
| | - Colin H Lipper
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Department of Cancer Biology, Dana Farber Cancer Institute, Boston, MA, USA
| | - Dongyuan Song
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Jesse V Kurland
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
| | - Julia M Rogers
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
- Committee on Higher Degrees in Biophysics, Harvard University, Cambridge, MA, USA
| | - Raehoon Jeong
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
- Bioinformatics and Integrative Genomics Graduate Program, Harvard University, Cambridge, MA, USA
| | - Stephen C Blacklow
- Program in Biological and Biomedical Sciences, Harvard University, Cambridge, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Department of Cancer Biology, Dana Farber Cancer Institute, Boston, MA, USA
- Committee on Higher Degrees in Biophysics, Harvard University, Cambridge, MA, USA
| | - Rafael A Irizarry
- Department of Data Science, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Martha L Bulyk
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA.
- Program in Biological and Biomedical Sciences, Harvard University, Cambridge, MA, USA.
- Committee on Higher Degrees in Biophysics, Harvard University, Cambridge, MA, USA.
- Bioinformatics and Integrative Genomics Graduate Program, Harvard University, Cambridge, MA, USA.
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
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2
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Peña-Martínez EG, Pomales-Matos DA, Rivera-Madera A, Messon-Bird JL, Medina-Feliciano JG, Sanabria-Alberto L, Barreiro-Rosario AC, Rivera-Del Valle J, Rodríguez-Ríos JM, Rodríguez-Martínez JA. Prioritizing cardiovascular disease-associated variants altering NKX2-5 and TBX5 binding through an integrative computational approach. J Biol Chem 2023; 299:105423. [PMID: 37926287 PMCID: PMC10750078 DOI: 10.1016/j.jbc.2023.105423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/18/2023] [Accepted: 10/26/2023] [Indexed: 11/07/2023] Open
Abstract
Cardiovascular diseases (CVDs) are the leading cause of death worldwide and are heavily influenced by genetic factors. Genome-wide association studies have mapped >90% of CVD-associated variants within the noncoding genome, which can alter the function of regulatory proteins, such as transcription factors (TFs). However, due to the overwhelming number of single-nucleotide polymorphisms (SNPs) (>500,000) in genome-wide association studies, prioritizing variants for in vitro analysis remains challenging. In this work, we implemented a computational approach that considers support vector machine (SVM)-based TF binding site classification and cardiac expression quantitative trait loci (eQTL) analysis to identify and prioritize potential CVD-causing SNPs. We identified 1535 CVD-associated SNPs within TF footprints and putative cardiac enhancers plus 14,218 variants in linkage disequilibrium with genotype-dependent gene expression in cardiac tissues. Using ChIP-seq data from two cardiac TFs (NKX2-5 and TBX5) in human-induced pluripotent stem cell-derived cardiomyocytes, we trained a large-scale gapped k-mer SVM model to identify CVD-associated SNPs that altered NKX2-5 and TBX5 binding. The model was tested by scoring human heart TF genomic footprints within putative enhancers and measuring in vitro binding through electrophoretic mobility shift assay. Five variants predicted to alter NKX2-5 (rs59310144, rs6715570, and rs61872084) and TBX5 (rs7612445 and rs7790964) binding were prioritized for in vitro validation based on the magnitude of the predicted change in binding and are in cardiac tissue eQTLs. All five variants altered NKX2-5 and TBX5 DNA binding. We present a bioinformatic approach that considers tissue-specific eQTL analysis and SVM-based TF binding site classification to prioritize CVD-associated variants for in vitro analysis.
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Affiliation(s)
- Edwin G Peña-Martínez
- Department of Biology, University of Puerto Rico Río Piedras Campus, San Juan, Puerto Rico
| | - Diego A Pomales-Matos
- Department of Biology, University of Puerto Rico Río Piedras Campus, San Juan, Puerto Rico
| | | | - Jean L Messon-Bird
- Department of Biology, University of Puerto Rico Río Piedras Campus, San Juan, Puerto Rico
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3
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Peña-Martínez EG, Pomales-Matos DA, Rivera-Madera A, Messon-Bird JL, Medina-Feliciano JG, Sanabria-Alberto L, Barreiro-Rosario AC, Rodriguez-Rios JM, Rodríguez-Martínez JA. Prioritizing Cardiovascular Disease-Associated Variants Altering NKX2-5 Binding through an Integrative Computational Approach. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.09.01.23294951. [PMID: 37693486 PMCID: PMC10491373 DOI: 10.1101/2023.09.01.23294951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Cardiovascular diseases (CVDs) are the leading cause of death worldwide and are heavily influenced by genetic factors. Genome-wide association studies (GWAS) have mapped > 90% of CVD-associated variants within the non-coding genome, which can alter the function of regulatory proteins, like transcription factors (TFs). However, due to the overwhelming number of GWAS single nucleotide polymorphisms (SNPs) (>500,000), prioritizing variants for in vitro analysis remains challenging. In this work, we implemented a computational approach that considers support vector machine (SVM)-based TF binding site classification and cardiac expression quantitative trait loci (eQTL) analysis to identify and prioritize potential CVD-causing SNPs. We identified 1,535 CVD-associated SNPs that occur within human heart footprints/enhancers and 9,309 variants in linkage disequilibrium (LD) with differential gene expression profiles in cardiac tissue. Using hiPSC-CM ChIP-seq data from NKX2-5 and TBX5, two cardiac TFs essential for proper heart development, we trained a large-scale gapped k-mer SVM (LS-GKM-SVM) predictive model that can identify binding sites altered by CVD-associated SNPs. The computational predictive model was tested by scoring human heart footprints and enhancers in vitro through electrophoretic mobility shift assay (EMSA). Three variants (rs59310144, rs6715570, and rs61872084) were prioritized for in vitro validation based on their eQTL in cardiac tissue and LS-GKM-SVM prediction to alter NKX2-5 DNA binding. All three variants altered NKX2-5 DNA binding. In summary, we present a bioinformatic approach that considers tissue-specific eQTL analysis and SVM-based TF binding site classification to prioritize CVD-associated variants for in vitro experimental analysis.
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4
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Lovato TL, Blotz B, Bileckyj C, Johnston CA, Cripps RM. Modeling a variant of unknown significance in the Drosophila ortholog of the human cardiogenic gene NKX2.5. Dis Model Mech 2023; 16:dmm050059. [PMID: 37691628 PMCID: PMC10548113 DOI: 10.1242/dmm.050059] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 09/05/2023] [Indexed: 09/12/2023] Open
Abstract
Sequencing of human genome samples has unearthed genetic variants for which functional testing is necessary to validate their clinical significance. We used the Drosophila system to analyze a variant of unknown significance in the human congenital heart disease gene NKX2.5 (also known as NKX2-5). We generated an R321N allele of the NKX2.5 ortholog tinman (tin) to model a human K158N variant and tested its function in vitro and in vivo. The R321N Tin isoform bound poorly to DNA in vitro and was deficient in activating a Tin-dependent enhancer in tissue culture. Mutant Tin also showed a significantly reduced interaction with a Drosophila T-box cardiac factor named Dorsocross1. We generated a tinR321N allele using CRISPR/Cas9, for which homozygotes were viable and had normal heart specification, but showed defects in the differentiation of the adult heart that were exacerbated by further loss of tin function. We propose that the human K158N variant is pathogenic through causing a deficiency in DNA binding and a reduced ability to interact with a cardiac co-factor, and that cardiac defects might arise later in development or adult life.
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Affiliation(s)
- TyAnna L. Lovato
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Brenna Blotz
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Cayleen Bileckyj
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | | | - Richard M. Cripps
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
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5
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Lovato TL, Blotz B, Bileckyj C, Johnston CA, Cripps RM. Using Drosophila to model a variant of unknown significance in the human cardiogenic gene Nkx2.5. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.28.546937. [PMID: 37425758 PMCID: PMC10327092 DOI: 10.1101/2023.06.28.546937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Sequencing of human genome samples has unearthed genetic variants for which functional testing is necessary to validate their clinical significance. We used the Drosophila system to analyze a variant of unknown significance in the human congenital heart disease gene, Nkx2 . 5 . We generated an R321N allele of the Nkx2 . 5 ortholog tinman ( tin ) to model a human K158N variant and tested its function in vitro and in vivo. The R321N Tin isoform bound poorly to DNA in vitro and was deficient in activating a Tin-dependent enhancer in tissue culture. Mutant Tin also showed a significantly reduced interaction with a Drosophila Tbox cardiac factor named Dorsocross1. We generated a tin R321N allele using CRISPR/Cas9, for which homozygotes were viable and had normal heart specification, but showed defects in the differentiation of the adult heart that were exacerbated by further loss of tin function. We conclude that the human K158N mutation is likely pathogenic through causing both a deficiency in DNA binding and a reduced ability to interact with a cardiac cofactor, and that cardiac defects might arise later in development or adult life.
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6
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Peña-Martínez EG, Rivera-Madera A, Pomales-Matos DA, Sanabria-Alberto L, Rosario-Cañuelas BM, Rodríguez-Ríos JM, Carrasquillo-Dones EA, Rodríguez-Martínez JA. Disease-associated non-coding variants alter NKX2-5 DNA-binding affinity. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194906. [PMID: 36690178 PMCID: PMC10013089 DOI: 10.1016/j.bbagrm.2023.194906] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 12/30/2022] [Accepted: 01/02/2023] [Indexed: 01/22/2023]
Abstract
Genome-wide association studies (GWAS) have mapped over 90 % of disease- or trait-associated variants within the non-coding genome, like cis-regulatory elements (CREs). Non-coding single nucleotide polymorphisms (SNPs) are genomic variants that can change how DNA-binding regulatory proteins, like transcription factors (TFs), interact with the genome and regulate gene expression. NKX2-5 is a TF essential for proper heart development, and mutations affecting its function have been associated with congenital heart diseases (CHDs). However, establishing a causal mechanism between non-coding genomic variants and human disease remains challenging. To address this challenge, we identified 8475 SNPs predicted to alter NKX2-5 DNA-binding using a position weight matrix (PWM)-based predictive model. Five variants were prioritized for in vitro validation; four of them are associated with traits and diseases that impact cardiovascular health. The impact of these variants on NKX2-5 binding was evaluated with electrophoretic mobility shift assay (EMSA) using purified recombinant NKX2-5 homeodomain. Binding curves were constructed to determine changes in binding between variant and reference alleles. Variants rs7350789, rs7719885, rs747334, and rs3892630 increased binding affinity, whereas rs61216514 decreased binding by NKX2-5 when compared to the reference genome. Our findings suggest that differential TF-DNA binding affinity can be key in establishing a causal mechanism of pathogenic variants.
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7
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Sezer A, Perçin FE, Kazan HH, Kayhan G, Akturk M. A de novo heterozygous HOXA11 variant in a patient with mesomelic dysplasia with urogenital abnormalities. Am J Med Genet A 2022; 188:1890-1895. [PMID: 35253374 DOI: 10.1002/ajmg.a.62713] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/18/2022] [Accepted: 02/05/2022] [Indexed: 12/27/2022]
Abstract
Mesomelic dysplasias are a genetically and clinically heterogeneous group of diseases with more than 10 types defined. This article presents an 18-year-old female patient with normal intelligence and a multisystem phenotype including disproportionate short stature, scoliosis, mesomelic limb shortening, radial bowing, short fourth to fifth metacarpals and metatarsals, fusions in the carpal/tarsal bones, operated pes equinovarus, primary amenorrhea, uterine hypoplasia, vesicoureteral reflux, and chronic kidney disease. Whole-exome sequencing revealed a de novo heterozygous c.881T>G (p.Met294Arg) variant in HOXA11 (NM_005523.6) gene. The variant was located in the homeodomain of HOXA11 and predicted to alter DNA-binding ability of the protein. In silico analyses indicated that the variant could promote the alterations in the protein-protein interaction. The possible functional effect of the variant was supposed as dominant-negative. Hoxa11-mutant mice have been reported to exhibit homeotic transformations in the thoracic and sacral vertebrae, zeugopodal phenotype in forelimb and hindlimb, and urogenital abnormalities. Although mice models were reported as mesomelic dysplasia and urogenital abnormalities (MDUGA), this phenotype has not yet been reported in humans. This was the first case with MDUGA putatively related to a de novo variant in HOXA11.
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Affiliation(s)
- Abdullah Sezer
- Department of Medical Genetics, Dr. Sami Ulus Maternity and Children's Training and Research Hospital, Ankara, Turkey.,Faculty of Medicine, Department of Medical Genetics, Gazi University, Ankara, Turkey
| | - Ferda Emriye Perçin
- Faculty of Medicine, Department of Medical Genetics, Gazi University, Ankara, Turkey
| | - Hasan Huseyin Kazan
- Faculty of Medicine, Department of Medical Genetics, Gazi University, Ankara, Turkey
| | - Gulsum Kayhan
- Faculty of Medicine, Department of Medical Genetics, Gazi University, Ankara, Turkey
| | - Mujde Akturk
- Faculty of Medicine, Department of Endocrinology and Metabolism, Gazi University, Ankara, Turkey
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8
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The transcriptional regulator HDP1 controls expansion of the inner membrane complex during early sexual differentiation of malaria parasites. Nat Microbiol 2022; 7:289-299. [PMID: 35087229 PMCID: PMC8852293 DOI: 10.1038/s41564-021-01045-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 12/08/2021] [Indexed: 12/28/2022]
Abstract
Transmission of Plasmodium falciparum and other malaria parasites requires their differentiation from asexual blood stages into gametocytes, the non-replicative sexual stage necessary to infect the mosquito vector. This transition involves changes in gene expression and chromatin reorganization that result in the activation and silencing of stage-specific genes. However, the genomes of malaria parasites have been noted for their limited number of transcriptional and chromatin regulators, and the molecular mediators of these changes remain largely unknown. We recently identified homeodomain protein 1 (HDP1) as a DNA-binding protein, first expressed in gametocytes, that enhances the expression of key genes critical for early sexual differentiation. The discovery of HDP1 marks a new class of transcriptional regulator in malaria parasites outside of the better-characterized ApiAP2 family. Here, using molecular biology, biochemistry and microscopy techniques, we show that HDP1 is essential for gametocyte maturation, facilitating the necessary upregulation of inner membrane complex components during early gametocytogenesis that gives P. falciparum gametocytes their characteristic shape.
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9
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EL Bouchikhi I, Belhassan K, Moufid FZ, Bouguenouch L, Samri I, Iraqui Houssaïni M, Ouldim K, Atmani S. Screening of NKX2.5 gene in Moroccan Tetralogy of Fallot (TOF) patients: worldwide mutation rate comparisons show a significant association between R25C variant and TOF phenotype. EGYPTIAN JOURNAL OF MEDICAL HUMAN GENETICS 2021. [DOI: 10.1186/s43042-021-00136-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Abstract
Background
Tetralogy of Fallot is the most prevalent cyanotic congenital heart disease, occurring in 1/3 600 live births. This disorder comprises ventricular septal defect, right ventricular outflow obstruction, over-riding aorta, and right ventricular hypertrophy. The present study aims to reveal the spectrum of Nk2 homeobox 5 (NKX2-5) variants identified in a Moroccan non-syndromic tetralogy of Fallot cohort and to compare mutation rate with different studies from all over the world. Thirty-one patients with non-syndromic tetralogy of Fallot were recruited in this cross-sectional study. DNAs were extracted, and coding regions of NKX2.5 were PCR-amplified and sequenced. The obtained sequences were analyzed using different bioinformatics tools. Statistical comparisons were carried out using the R software.
Results
R25C mutation was found in two patients, in association with the E21E variant. The latter variant was frequently observed in the population and seems to have a potential altering effect on the splicing process. The NKX2.5 mutation rate in our tetralogy of Fallot population is around 6.4%, and no significant difference was noticed in comparison with previous studies. At the same time, a comparison of R25C mutation rate between atrial septal defect and tetralogy of Fallot worldwide populations shows a particular association of R25C mutation with tetralogy of Fallot phenotype.
Conclusions
This study reveals a consistency between our NKX2.5 mutation rate and those of different tetralogy of Fallot populations around the world. Our findings suggest a possible combined effect of R25C mutation and E21E variant on the carriers and emphasize particularly the significant association of R25C mutation with tetralogy of Fallot, which highlights the importance of an anticipative screening for TOF phenotype among the carriers’ offspring at the perinatal period.
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Morlanes-Gracia P, Antoniutti G, Alvarez-Rubio J, Torres-Juan L, Heine-Suñer D, Ripoll-Vera T. Case Report: A Novel NKX2-5 Mutation in a Family With Congenital Heart Defects, Left Ventricular Non-compaction, Conduction Disease, and Sudden Cardiac Death. Front Cardiovasc Med 2021; 8:691203. [PMID: 34277740 PMCID: PMC8280289 DOI: 10.3389/fcvm.2021.691203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 06/01/2021] [Indexed: 01/27/2023] Open
Abstract
The NKX2-5 gene encodes for a transcription factor crucial for cardiac cell differentiation and proliferation. It was the first gene associated with congenital heart disease (CHD) in humans and has been linked to conduction disorders or cardiomyopathies. However, an overlapping phenotype is not frequent in the literature. We describe a family with a novel missense mutation in the NKX2-5 gene (p.Gln181Pro) with numerous antecedents with atrial septal defect (ASD), left ventricular non-compaction (LVNC), conduction disease, and sudden cardiac death (SCD).
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Affiliation(s)
| | | | - Jorge Alvarez-Rubio
- Hospital Universitario Son LLàtzer, Palma de Mallorca, Spain.,Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma de Mallorca, Spain
| | - Laura Torres-Juan
- Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma de Mallorca, Spain.,Departmento de Genetica Clínica y Molecular, Hospital Universitario Son Espases, Palma de Mallorca, Spain
| | - Damian Heine-Suñer
- Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma de Mallorca, Spain.,Departmento de Genetica Clínica y Molecular, Hospital Universitario Son Espases, Palma de Mallorca, Spain
| | - Tomás Ripoll-Vera
- Hospital Universitario Son LLàtzer, Palma de Mallorca, Spain.,Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma de Mallorca, Spain.,Centro de Investigación Biomédica CIBEROBN, Madrid, Spain
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11
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Crystal Structures of Ternary Complexes of MEF2 and NKX2-5 Bound to DNA Reveal a Disease Related Protein-Protein Interaction Interface. J Mol Biol 2020; 432:5499-5508. [PMID: 32681840 DOI: 10.1016/j.jmb.2020.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/08/2020] [Accepted: 07/09/2020] [Indexed: 11/22/2022]
Abstract
MEF2 and NKX2-5 transcription factors interact with each other in cardiogenesis and are necessary for normal heart formation. Despite evidence suggesting that these two transcription factors function synergistically and possibly through direct physical interactions, molecular mechanisms by which they interact are not clear. Here we determined the crystal structures of ternary complexes of MEF2 and NKX2-5 bound to myocardin enhancer DNA in two crystal forms. These crystal structures are the first example of human MADS-box/homeobox ternary complex structures involved in cardiogenesis. Our structures reveal two possible modes of interactions between MEF2 and NKX2-5: MEF2 and NKX bind to adjacent DNA sites to recognize DNA in cis; and MEF2 and NKX bind to different DNA strands to interact with each other in trans via a conserved protein-protein interface observed in both crystal forms. Disease-related mutations are mapped to the observed protein-protein interface. Our structural studies provide a starting point to understand and further study the molecular mechanisms of the interactions between MEF2 and NKX2.5 and their roles in cardiogenesis.
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12
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Kolomenski JE, Delea M, Simonetti L, Fabbro MC, Espeche LD, Taboas M, Nadra AD, Bruque CD, Dain L. An update on genetic variants of the NKX2-5. Hum Mutat 2020; 41:1187-1208. [PMID: 32369864 DOI: 10.1002/humu.24030] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 04/03/2020] [Accepted: 04/26/2020] [Indexed: 12/13/2022]
Abstract
NKX2-5 is a homeodomain transcription factor that plays a crucial role in heart development. It is the first gene where a single genetic variant (GV) was found to be associated with congenital heart diseases in humans. In this study, we carried out a comprehensive survey of NKX2-5 GVs to build a unified, curated, and updated compilation of all available GVs. We retrieved a total of 1,380 unique GVs. From these, 970 had information on their frequency in the general population and 143 have been linked to pathogenic phenotypes in humans. In vitro effect was ascertained for 38 GVs. The homeodomain had the biggest cluster of pathogenic variants in the protein: 49 GVs in 60 residues, 23 in its third α-helix, where 11 missense variants may affect protein-DNA interaction or the hydrophobic core. We also pinpointed the likely location of pathogenic GVs in four linear motifs. These analyses allowed us to assign a putative explanation for the effect of 90 GVs. This study pointed to reliable pathogenicity for GVs in helix 3 of the homeodomain and may broaden the scope of functional and structural studies that can be done to better understand the effect of GVs in NKX2-5 function.
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Affiliation(s)
- Jorge E Kolomenski
- Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, IQUIBICEN-CONICET, Buenos Aires, Argentina.,Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biología Traslacional, iB3, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Marisol Delea
- Centro Nacional de Genética Médica, ANLIS, Buenos Aires, Argentina
| | - Leandro Simonetti
- Department of Chemistry-Biomedical Centre, Uppsala University, Uppsala, Sweden
| | | | - Lucía D Espeche
- Centro Nacional de Genética Médica, ANLIS, Buenos Aires, Argentina
| | - Melisa Taboas
- Centro Nacional de Genética Médica, ANLIS, Buenos Aires, Argentina
| | - Alejandro D Nadra
- Departamento de Química Biológica Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, IQUIBICEN-CONICET, Buenos Aires, Argentina.,Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biología Traslacional, iB3, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Carlos D Bruque
- Centro Nacional de Genética Médica, ANLIS, Buenos Aires, Argentina.,Instituto de Biología y Medicina Experimental, (IBYME-CONICET), Buenos Aires, Argentina
| | - Liliana Dain
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Instituto de Biociencias, Biotecnología y Biología Traslacional, iB3, Universidad de Buenos Aires, Buenos Aires, Argentina.,Centro Nacional de Genética Médica, ANLIS, Buenos Aires, Argentina.,Instituto de Biología y Medicina Experimental, (IBYME-CONICET), Buenos Aires, Argentina
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13
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Sveinbjornsson G, Olafsdottir EF, Thorolfsdottir RB, Davidsson OB, Helgadottir A, Jonasdottir A, Jonasdottir A, Bjornsson E, Jensson BO, Arnadottir GA, Kristinsdottir H, Stephensen SS, Oskarsson G, Gudbjartsson T, Sigurdsson EL, Andersen K, Danielsen R, Arnar DO, Jonsdottir I, Thorsteinsdottir U, Sulem P, Thorgeirsson G, Gudbjartsson DF, Holm H, Stefansson K. Variants in NKX2-5 and FLNC Cause Dilated Cardiomyopathy and Sudden Cardiac Death. CIRCULATION-GENOMIC AND PRECISION MEDICINE 2019; 11:e002151. [PMID: 30354339 DOI: 10.1161/circgen.117.002151] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Dilated cardiomyopathy (DCM) is an important cause of heart failure. Variants in >50 genes have been reported to cause DCM, but causative variants have been found in less than half of familial cases. Variants causing DCM in Iceland have not been reported before. METHODS We performed a genome-wide association study on DCM based on whole genome sequencing. We tested the association of 32.5 million sequence variants in 424 cases and 337 689 population controls in Iceland. RESULTS We identified 2 DCM variants in established cardiomyopathy genes, a missense variant p.Phe145Leu in NKX2-5 carried by 1 in 7100 Icelanders ( P=7.0×10-12) and a frameshift variant p.Phe1626Serfs*40 in FLNC carried by 1 in 3600 Icelanders ( P=2.1×10-10). Both variants associate with heart failure and sudden cardiac death. Additionally, p.Phe145Leu in NKX2-5 associates with high degree atrioventricular block and atrial septal defect ( P<1.4×10-4). The penetrance of serious heart disease among carriers of the NKX2-5 variant is high and higher than that of the FLNC variant. CONCLUSIONS Two rare variants in NKX2-5 and FLNC, carried by 1 in 2400 Icelanders, cause familial DCM in Iceland. These genes have recently been associated with DCM. Given the serious consequences of these variants, we suggest screening for them in individuals with DCM and their family members, with subsequent monitoring of carriers, offering early intervention.
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Affiliation(s)
- Gardar Sveinbjornsson
- deCODE genetics/Amgen, Inc, Reykjavik, Iceland (G.S., E.F.O., R.B.T., O.B.D., A.H.,School of Engineering and Natural Sciences (G.S., D.F.G.)
| | - Eva F Olafsdottir
- deCODE genetics/Amgen, Inc, Reykjavik, Iceland (G.S., E.F.O., R.B.T., O.B.D., A.H.,Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.)
| | | | - Olafur B Davidsson
- deCODE genetics/Amgen, Inc, Reykjavik, Iceland (G.S., E.F.O., R.B.T., O.B.D., A.H
| | - Anna Helgadottir
- deCODE genetics/Amgen, Inc, Reykjavik, Iceland (G.S., E.F.O., R.B.T., O.B.D., A.H
| | | | | | - Eythor Bjornsson
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.).,Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.)
| | - Brynjar O Jensson
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.)
| | - Gudny A Arnadottir
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.)
| | | | - Sigurdur S Stephensen
- Department of Pediatric Cardiology, Children's Hospital Reykjavik, Iceland (S.S.S., G.O.)
| | - Gylfi Oskarsson
- Department of Pediatric Cardiology, Children's Hospital Reykjavik, Iceland (S.S.S., G.O.)
| | - Tomas Gudbjartsson
- Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.).,Department of Cardiothoracic Surgery (T.G.)
| | - Emil L Sigurdsson
- Department of Family Medicine (E.L.S.), University of Iceland, Reykjavik.,Department of Development, Primary Health Care of the Capital Area, Reykjavik, Iceland (E.L.S.)
| | - Karl Andersen
- Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.).,Department of Medicine, Landspitali University Hospital, Reykjavik, Iceland (K.A., R.D., D.O.A., G.T.)
| | - Ragnar Danielsen
- Department of Medicine, Landspitali University Hospital, Reykjavik, Iceland (K.A., R.D., D.O.A., G.T.)
| | - David O Arnar
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.).,Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.).,Department of Medicine, Landspitali University Hospital, Reykjavik, Iceland (K.A., R.D., D.O.A., G.T.)
| | - Ingileif Jonsdottir
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.).,Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.).,Department of Immunology, Landspitali, The National University Hospital of Iceland, Reykjavik (I.J.)
| | - Unnur Thorsteinsdottir
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.).,Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.)
| | - Patrick Sulem
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.)
| | - Gudmundur Thorgeirsson
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.).,Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.).,Department of Medicine, Landspitali University Hospital, Reykjavik, Iceland (K.A., R.D., D.O.A., G.T.)
| | - Daniel F Gudbjartsson
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.).,School of Engineering and Natural Sciences (G.S., D.F.G.)
| | - Hilma Holm
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.)
| | - Kari Stefansson
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.).,Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.)
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14
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Li S, Pradhan L, Ashur S, Joshi A, Nam HJ. Crystal Structure of FOXC2 in Complex with DNA Target. ACS OMEGA 2019; 4:10906-10914. [PMID: 31460188 PMCID: PMC6648891 DOI: 10.1021/acsomega.9b00756] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 05/22/2019] [Indexed: 06/10/2023]
Abstract
Forkhead transcription factor C2 (FOXC2) is a transcription factor regulating vascular and lymphatic development, and its mutations are linked to lymphedema-distichiasis syndrome. FOXC2 is also a crucial regulator of the epithelial-mesenchymal transition processes essential for tumor metastasis. Here, we report the crystal structure of the FOXC2-DNA-binding domain in complex with its cognate DNA. The crystal structure provides the basis of DNA sequence recognition by FOXC2 for the T/CAAAC motif. Helix 3 makes the majority of the DNA-protein interactions and confers the DNA sequence specificity. The computational energy calculation results also validate the structural observations. The FOXC2 and DNA complex structure provides a detailed picture of protein and DNA interactions, which allows us to predict its DNA recognition specificity and impaired functions in mutants identified in human patients.
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15
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Jakubec D, Vondrášek J. Can All-Atom Molecular Dynamics Simulations Quantitatively Describe Homeodomain-DNA Binding Equilibria? J Chem Theory Comput 2019; 15:2635-2648. [PMID: 30807142 DOI: 10.1021/acs.jctc.8b01144] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We systematically investigate the applicability of a molecular dynamics-based setup for the calculations of standard binding free energies of biologically relevant protein-DNA complexes. The free energies are extracted from a potential of mean force calculated using umbrella sampling simulations. Two protein-DNA systems derived from a homeodomain transcription factor complex are studied in order to investigate the binding of both disordered and globular proteins. Free energies and trajectories obtained using two modern molecular mechanical force fields are compared to each other and to experimental data. The temperature dependence of the calculated standard binding free energies is investigated by performing all simulations over a range of temperatures. We show that the values of standard binding free energies obtained from these simulations are overestimated compared to experimental results. Significant differences are observed between the two protein-DNA systems and between the two force fields, which are explained by different propensities to form inter- and intramolecular contacts. The number of protein-DNA contacts increases with increasing temperature, in agreement with the experimentally known temperature dependence of enthalpies of binding. However, conclusions about the temperature dependence of the standard binding free energies cannot be made with confidence, as the differences among the values are on the order of statistical uncertainty.
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Affiliation(s)
- David Jakubec
- Bioinformatics Group, Institute of Organic Chemistry and Biochemistry , Czech Academy of Sciences , 166 10 Praha 6, Czech Republic.,Department of Physical and Macromolecular Chemistry, Faculty of Science , Charles University , 128 43 Praha 2, Czech Republic
| | - Jiří Vondrášek
- Bioinformatics Group, Institute of Organic Chemistry and Biochemistry , Czech Academy of Sciences , 166 10 Praha 6, Czech Republic
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16
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Mattapally S, Singh M, Murthy KS, Asthana S, Banerjee SK. Computational modeling suggests impaired interactions between NKX2.5 and GATA4 in individuals carrying a novel pathogenic D16N NKX2.5 mutation. Oncotarget 2018; 9:13713-13732. [PMID: 29568389 PMCID: PMC5862610 DOI: 10.18632/oncotarget.24459] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 01/24/2018] [Indexed: 12/31/2022] Open
Abstract
NKX2.5, a homeobox containing gene, plays an important role in embryonic heart development and associated mutations are linked with various cardiac abnormalities. We sequenced the NKX2.5 gene in 100 congenital heart disease (CHD) patients and 200 controls. Our analysis revealed a total of 7 mutations, 3 in intronic region, 3 in coding region and 1 in 3’ UTR. Of the above mutations, one mutation was found to be associated with tetralogy of fallot (TOF) and two (rs2277923 and a novel mutation, D16N) were strongly associated with VSD. A novel missense mutation, D16N (p-value =0.009744), located in the tinman (TN) region and associated with ventricular septal defect (VSD), is the most significant findings of this study. Computational analysis revealed that D16N mutation is pathogenic in nature. Through the molecular modeling, docking and molecular dynamics simulation studies, we have identified the location of mutant D16N in NKX2.5 and its interaction map with other partners at the atomic level. We found NKX2.5-GATA4 complex is stable, however, in case of mutant we observed significant conformational changes and loss of key polar interactions, which might be a cause of the pathogenic behavior. This study underscores the structural basis of D16N pathogenic mutation in the regulation of NKX2.5 and how this mutation renders the structural-functional divergence that possibly leading towards the diseased state.
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Affiliation(s)
- Saidulu Mattapally
- Division of Medicinal Chemistry and Pharmacology, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India
| | - Mrityunjay Singh
- Drug Discovery Research Center (DDRC), Translational Health Science and Technology Institute (THSTI), Faridabad, Haryana 121001, India
| | | | - Shailendra Asthana
- Drug Discovery Research Center (DDRC), Translational Health Science and Technology Institute (THSTI), Faridabad, Haryana 121001, India
| | - Sanjay K Banerjee
- Division of Medicinal Chemistry and Pharmacology, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India.,Drug Discovery Research Center (DDRC), Translational Health Science and Technology Institute (THSTI), Faridabad, Haryana 121001, India
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17
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Dorboz I, Aiello C, Simons C, Stone RT, Niceta M, Elmaleh M, Abuawad M, Doummar D, Bruselles A, Wolf NI, Travaglini L, Boespflug-Tanguy O, Tartaglia M, Vanderver A, Rodriguez D, Bertini E. Biallelic mutations in the homeodomain of NKX6-2 underlie a severe hypomyelinating leukodystrophy. Brain 2017; 140:2550-2556. [PMID: 28969374 DOI: 10.1093/brain/awx207] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 07/04/2017] [Indexed: 11/14/2022] Open
Abstract
Hypomyelinating leukodystrophies are genetically heterogeneous disorders with overlapping clinical and neuroimaging features reflecting variable abnormalities in myelin formation. We report on the identification of biallelic inactivating mutations in NKX6-2, a gene encoding a transcription factor regulating multiple developmental processes with a main role in oligodendrocyte differentiation and regulation of myelin-specific gene expression, as the cause underlying a previously unrecognized severe variant of hypomyelinating leukodystrophy. Five affected subjects (three unrelated families) were documented to share biallelic inactivating mutations affecting the NKX6-2 homeobox domain. A trio-based whole exome sequencing analysis in the first family detected a homozygous frameshift change [c.606delinsTA; p.(Lys202Asnfs*?)]. In the second family, homozygosity mapping coupled to whole exome sequencing identified a homozygous nucleotide substitution (c.565G>T) introducing a premature stop codon (p.Glu189*). In the third family, whole exome sequencing established compound heterozygosity for a non-conservative missense change affecting a key residue participating in DNA binding (c.599G>A; p.Arg200Gln) and a nonsense substitution (c.589C>T; p.Gln197*), in both affected siblings. The clinical presentation was homogeneous, with four subjects having severe motor delays, nystagmus and absent head control, and one individual showing gross motor delay at the age of 6 months. All exhibited neuroimaging that was consistent with hypomyelination. These findings define a novel, severe form of leukodystrophy caused by impaired NKX6-2 function.
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Affiliation(s)
- Imen Dorboz
- INSERM UMR 1141, DHU PROTECT, Paris Diderot University, Sorbonne Paris Cité, France, Paris 06, Paris, France
| | - Chiara Aiello
- Unit of Neuromuscular and Neurodegnerative Disorders, Laboratory of Molecular Medicine, Bambino Gesu' Children's Hospital, Rome, Italy.,Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Cas Simons
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, 4072, Australia
| | - Robert Thompson Stone
- Pediatric Multiple Sclerosis and Neuroimmunology Program, University of Rochester, Rochester, USA
| | - Marcello Niceta
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Monique Elmaleh
- AP-HP, Department of Child Radiology, Robert Debré Hospital, Paris, France
| | - Mohammad Abuawad
- INSERM UMR 1141, DHU PROTECT, Paris Diderot University, Sorbonne Paris Cité, France, Paris 06, Paris, France
| | - Diane Doummar
- APHP, Department of Neuropediatrics, National Reference Center for Neurogenetic Disorders, Hôpital Armand-Trousseau, GHUEP, Paris, France.,GRC ConCer-LD, Sorbonne Universités, UPMC Université, Paris, France
| | - Alessandro Bruselles
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy
| | - Nicole I Wolf
- Department of Child Neurology, VU University Medical Center, Amsterdam, and Amsterdam Neuroscience, Amsterdam, The Netherlands
| | - Lorena Travaglini
- Unit of Neuromuscular and Neurodegnerative Disorders, Laboratory of Molecular Medicine, Bambino Gesu' Children's Hospital, Rome, Italy.,Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Odile Boespflug-Tanguy
- INSERM UMR 1141, DHU PROTECT, Paris Diderot University, Sorbonne Paris Cité, France, Paris 06, Paris, France.,AP-HP, Department of Neuropediatrics and Metabolic Diseases, National Reference Center for Leukodystrophies, Robert Debré Hospital, Paris, France
| | - Marco Tartaglia
- Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
| | - Adeline Vanderver
- Division of Neurology, Children's Hospital of Philadelphia, USA.,Department of Neurology, University of Pennsylvania, USA
| | - Diana Rodriguez
- APHP, Department of Neuropediatrics, National Reference Center for Neurogenetic Disorders, Hôpital Armand-Trousseau, GHUEP, Paris, France.,GRC ConCer-LD, Sorbonne Universités, UPMC Université, Paris, France
| | - Enrico Bertini
- Unit of Neuromuscular and Neurodegnerative Disorders, Laboratory of Molecular Medicine, Bambino Gesu' Children's Hospital, Rome, Italy.,Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy
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18
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New Insights into Cooperative Binding of Homeodomain Transcription Factors PREP1 and PBX1 to DNA. Sci Rep 2017; 7:40665. [PMID: 28094776 PMCID: PMC5240567 DOI: 10.1038/srep40665] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 12/09/2016] [Indexed: 01/13/2023] Open
Abstract
PREP1 and PBX1 are homeodomain (HD) transcription factors that play crucial roles in embryonic development. Here, we present the first biophysical characterization of a PREP1 HD, and the NMR spectroscopic study of its DNA binding pocket. The data show that residues flanking the HD participate in DNA binding. The kinetic parameters for DNA binding of individual PREP1 and PBX1 HDs, and of their combination, show that isolated PREP1 and PBX1 HDs bind to DNA in a cooperative manner. A novel PREP1 motif, flanking the HD at the C-terminus, is required for cooperativity.
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19
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Pradhan L, Gopal S, Li S, Ashur S, Suryanarayanan S, Kasahara H, Nam HJ. Intermolecular Interactions of Cardiac Transcription Factors NKX2.5 and TBX5. Biochemistry 2016; 55:1702-10. [DOI: 10.1021/acs.biochem.6b00171] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Lagnajeet Pradhan
- Department
of Bioengineering, University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Sunil Gopal
- Department
of Bioengineering, University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Shichang Li
- Department
of Bioengineering, University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Shayan Ashur
- Department
of Bioengineering, University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Saai Suryanarayanan
- Department
of Bioengineering, University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Hideko Kasahara
- Department of Functional Genomics, University of Florida, Gainesville, Florida 32610, United States
| | - Hyun-Joo Nam
- Department
of Bioengineering, University of Texas at Dallas, Richardson, Texas 75080, United States
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20
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Luna-Zurita L, Stirnimann CU, Glatt S, Kaynak BL, Thomas S, Baudin F, Samee MAH, He D, Small EM, Mileikovsky M, Nagy A, Holloway AK, Pollard KS, Müller CW, Bruneau BG. Complex Interdependence Regulates Heterotypic Transcription Factor Distribution and Coordinates Cardiogenesis. Cell 2016; 164:999-1014. [PMID: 26875865 DOI: 10.1016/j.cell.2016.01.004] [Citation(s) in RCA: 146] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Revised: 11/21/2015] [Accepted: 12/22/2015] [Indexed: 12/26/2022]
Abstract
Transcription factors (TFs) are thought to function with partners to achieve specificity and precise quantitative outputs. In the developing heart, heterotypic TF interactions, such as between the T-box TF TBX5 and the homeodomain TF NKX2-5, have been proposed as a mechanism for human congenital heart defects. We report extensive and complex interdependent genomic occupancy of TBX5, NKX2-5, and the zinc finger TF GATA4 coordinately controlling cardiac gene expression, differentiation, and morphogenesis. Interdependent binding serves not only to co-regulate gene expression but also to prevent TFs from distributing to ectopic loci and activate lineage-inappropriate genes. We define preferential motif arrangements for TBX5 and NKX2-5 cooperative binding sites, supported at the atomic level by their co-crystal structure bound to DNA, revealing a direct interaction between the two factors and induced DNA bending. Complex interdependent binding mechanisms reveal tightly regulated TF genomic distribution and define a combinatorial logic for heterotypic TF regulation of differentiation.
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Affiliation(s)
- Luis Luna-Zurita
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA; Roddenberry Center for Stem Cell Biology and Medicine at Gladstone, San Francisco, CA 94158, USA
| | - Christian U Stirnimann
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Sebastian Glatt
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Bogac L Kaynak
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA; Roddenberry Center for Stem Cell Biology and Medicine at Gladstone, San Francisco, CA 94158, USA
| | - Sean Thomas
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA
| | - Florence Baudin
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany; UJF-EMBL-CNRS UMI 3265, Unit of Virus Host-Cell Interactions, 38042 Grenoble Cedex 9, France
| | | | - Daniel He
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA; Roddenberry Center for Stem Cell Biology and Medicine at Gladstone, San Francisco, CA 94158, USA
| | - Eric M Small
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Maria Mileikovsky
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
| | - Andras Nagy
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada; Department of Obstetrics and Gynaecology and Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Alisha K Holloway
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA; Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Katherine S Pollard
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA; Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Christoph W Müller
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
| | - Benoit G Bruneau
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA; Roddenberry Center for Stem Cell Biology and Medicine at Gladstone, San Francisco, CA 94158, USA; Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94143, USA; Department of Pediatrics, University of California, San Francisco, San Francisco, CA 94143, USA.
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21
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Nishi Y, Zhang X, Jeong J, Peterson KA, Vedenko A, Bulyk ML, Hide WA, McMahon AP. A direct fate exclusion mechanism by Sonic hedgehog-regulated transcriptional repressors. Development 2015; 142:3286-93. [PMID: 26293298 DOI: 10.1242/dev.124636] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Accepted: 08/04/2015] [Indexed: 01/19/2023]
Abstract
Sonic hedgehog (Shh) signaling patterns the vertebrate spinal cord by activating a group of transcriptional repressors in distinct neural progenitors of somatic motor neuron and interneuron subtypes. To identify the action of this network, we performed a genome-wide analysis of the regulatory actions of three key ventral determinants in mammalian neural tube patterning: Nkx2.2, Nkx6.1 and Olig2. Previous studies have demonstrated that each factor acts predominantly as a transcriptional repressor, at least in part, to inhibit alternative progenitor fate choices. Here, we reveal broad and direct repression of multiple alternative fates as a general mechanism of repressor action. Additionally, the repressor network targets multiple Shh signaling components providing negative feedback to ongoing Shh signaling. Analysis of chromatin organization around Nkx2.2-, Nkx6.1- and Olig2-bound regions, together with co-analysis of engagement of the transcriptional activator Sox2, indicate that repressors bind to, and probably modulate the action of, neural enhancers. Together, the data suggest a model for neural progenitor specification downstream of Shh signaling, in which Nkx2.2 and Olig2 direct repression of alternative neural progenitor fate determinants, an action augmented by the overlapping activity of Nkx6.1 in each cell type. Integration of repressor and activator inputs, notably activator inputs mediated by Sox2, is probably a key mechanism in achieving cell type-specific transcriptional outcomes in mammalian neural progenitor fate specification.
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Affiliation(s)
- Yuichi Nishi
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad CIRM Center for Regenerative Medicine and Stem Cell Research, University of Southern California Keck School of Medicine, Los Angeles, CA 90089, USA
| | - Xiaoxiao Zhang
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA
| | - Jieun Jeong
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA Department of Biostatistics, Harvard School of Public Health, Boston, MA 02115, USA
| | - Kevin A Peterson
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad CIRM Center for Regenerative Medicine and Stem Cell Research, University of Southern California Keck School of Medicine, Los Angeles, CA 90089, USA
| | - Anastasia Vedenko
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Martha L Bulyk
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Winston A Hide
- Department of Biostatistics, Harvard School of Public Health, Boston, MA 02115, USA Sheffield Institute for Translational Neuroscience, Department of Neuroscience, University of Sheffield, 385A Glossop Road, Sheffield S10 2HQ, UK
| | - Andrew P McMahon
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad CIRM Center for Regenerative Medicine and Stem Cell Research, University of Southern California Keck School of Medicine, Los Angeles, CA 90089, USA
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22
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Wang J, Mao JH, Ding KK, Xu WJ, Liu XY, Qiu XB, Li RG, Qu XK, Xu YJ, Huang RT, Xue S, Yang YQ. A novel NKX2.6 mutation associated with congenital ventricular septal defect. Pediatr Cardiol 2015; 36:646-56. [PMID: 25380965 DOI: 10.1007/s00246-014-1060-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Accepted: 10/31/2014] [Indexed: 12/18/2022]
Abstract
Congenital heart disease (CHD) is the most common birth defect and is the most prevalent non-infectious cause of infant death. Aggregating evidence demonstrates that genetic defects are involved in the pathogenesis of CHD. However, CHD is genetically heterogeneous and the genetic determinants for CHD in an overwhelming majority of patients remain unknown. In this study, the coding regions and splice junctions of the NKX2.6 gene, which encodes a homeodomain transcription factor crucial for cardiovascular development, were sequenced in 210 unrelated CHD patients. As a result, a novel heterozygous NKX2.6 mutation, p.K152Q, was identified in an index patient with ventricular septal defect (VSD). Genetic analysis of the proband's available family members showed that the mutation cosegregated with VSD transmitted as an autosomal dominant trait with complete penetrance. The missense mutation was absent in 400 control chromosomes and the altered amino acid was completely conserved evolutionarily across species. Due to unknown transcriptional targets of NKX2.6, the functional characteristics of the identified mutation at transcriptional activity were analyzed by using NKX2.5 as a surrogate. Alignment between human NKX2.6 and NKX2.5 proteins displayed that K152Q-mutant NKX2.6 was equivalent to K158Q-mutant NKX2.5, and introduction of K158Q into NKX2.5 significantly reduced its transcriptional activating function when compared with its wild-type counterpart. This study firstly links NKX2.6 loss-of-function mutation with increased susceptibility to isolated VSD, providing novel insight into the molecular mechanism underpinning VSD and contributing to the development of new preventive and therapeutic strategies for this common form of CHD.
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Affiliation(s)
- Juan Wang
- Department of Cardiology, Tongji Hospital, Tongji University School of Medicine, 389 Xincun Road, Shanghai, 200065, China,
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23
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Pradhan L, Nam HJ. NuProPlot: nucleic acid and protein interaction analysis and plotting program. ACTA ACUST UNITED AC 2015; 71:667-74. [DOI: 10.1107/s1399004715000139] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 01/06/2015] [Indexed: 11/10/2022]
Abstract
Growing numbers of protein and nucleic acid complex structures are being determined and deposited in the Protein Data Bank and the Nucleic Acid Database. With the increasing complexity of these structures, it is challenging to analyse and visualize the three-dimensional interactions. The currently available programs for such analysis and visualization are limited in their applications. They can only analyse a subset of protein–nucleic acid complexes and require multiple iterations before obtaining plots that are suitable for presentation. An interactive web-based program,NuProPlot(http://www.nuproplot.com), has been developed which can automatically identify hydrogen, electrostatic and van der Waals interactions between proteins and nucleic acids and generate a plot showing all of the interactions. Protein–DNA and protein–RNA interactions can be visualized in simple two-dimensional schematics. Interactive schematic drawing options allow selection of the plotted area and repositioning of the individual interactions for better legibility.NuProPlotis a fully automated and user-friendly program providing various custom options.NuProPlotrepresents a greatly improved option for analysis and presentation of protein–nucleic acid interactions.
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24
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Kachhap S, Singh B. Role of DNA conformation & energetic insights in Msx-1-DNA recognition as revealed by molecular dynamics studies on specific and nonspecific complexes. J Biomol Struct Dyn 2015; 33:2069-82. [PMID: 25484111 DOI: 10.1080/07391102.2014.995709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
In most of homeodomain-DNA complexes, glutamine or lysine is present at 50th position and interacts with 5th and 6th nucleotide of core recognition region. Molecular dynamics simulations of Msx-1-DNA complex (Q50-TG) and its variant complexes, that is specific (Q50K-CC), nonspecific (Q50-CC) having mutation in DNA and (Q50K-TG) in protein, have been carried out. Analysis of protein-DNA interactions and structure of DNA in specific and nonspecific complexes show that amino acid residues use sequence-dependent shape of DNA to interact. The binding free energies of all four complexes were analysed to define role of amino acid residue at 50th position in terms of binding strength considering the variation in DNA on stability of protein-DNA complexes. The order of stability of protein-DNA complexes shows that specific complexes are more stable than nonspecific ones. Decomposition analysis shows that N-terminal amino acid residues have been found to contribute maximally in binding free energy of protein-DNA complexes. Among specific protein-DNA complexes, K50 contributes more as compared to Q50 towards binding free energy in respective complexes. The sequence dependence of local conformation of DNA enables Q50/Q50K to make hydrogen bond with nucleotide(s) of DNA. The changes in amino acid sequence of protein are accommodated and stabilized around TAAT core region of DNA having variation in nucleotides.
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Affiliation(s)
- Sangita Kachhap
- a Bioinformatics Centre , CSIR-Institute of Microbial Technology , Sector 39A, Chandigarh , India
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25
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A novel NKX2.5 loss-of-function mutation associated with congenital bicuspid aortic valve. Am J Cardiol 2014; 114:1891-5. [PMID: 25438918 DOI: 10.1016/j.amjcard.2014.09.028] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 09/17/2014] [Accepted: 09/17/2014] [Indexed: 01/08/2023]
Abstract
Bicuspid aortic valve (BAV) is the most common form of congenital cardiovascular defect in humans and is associated with substantial morbidity and mortality. Emerging evidence demonstrates that genetic risk factors play an important role in the pathogenesis of BAV. However, BAV is a genetically heterogenous disorder, and the genetic defects underpinning BAV in most patients remain to be identified. In the present study, the coding exons and flanking introns of the NKX2.5 gene, which encodes a homeodomain-containing transcription factor essential for the normal development of the aortic valve, were sequenced in 142 unrelated patients with BAV. The available relatives of the mutation carrier and 200 unrelated healthy subjects used as controls were also genotyped for NKX2.5. The functional characteristics of the mutation were delineated by using a dual-luciferase reporter assay system. As a result, a novel heterozygous NKX2.5 mutation, p.K192X, was identified in a family with BAV transmitted in an autosomal dominant pattern. The nonsense mutation was absent in 400 control chromosomes. Functional analyses revealed that the mutant NKX2.5 had no transcriptional activity compared with its wild-type counterpart. Furthermore, the mutation abolished the synergistic transcriptional activation between NKX2.5 and GATA5, another transcription factor crucial for the aortic valvular morphogenesis. In conclusion, this study is the first to link an NKX2.5 loss-of-function mutation to enhanced susceptibility to human BAV, providing novel insight into the molecular mechanism of BAV and suggesting potential implications for genetic counseling and clinical care of families presenting with BAV.
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26
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Edwards N, Rice SJ, Raman S, Hynes AM, Srivastava S, Moore I, Al-Hamed M, Xu Y, Santibanez-Koref M, Thwaites DT, Gale DP, Sayer JA. A novel LMX1B mutation in a family with end-stage renal disease of 'unknown cause'. Clin Kidney J 2014; 8:113-9. [PMID: 25713721 PMCID: PMC4310431 DOI: 10.1093/ckj/sfu129] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 11/05/2014] [Indexed: 12/11/2022] Open
Abstract
End-stage renal disease (ESRD) presenting in a familial autosomal dominant pattern points to an underlying monogenic cause. Nail-patella syndrome (NPS) is an autosomal dominant disorder that may lead to ESRD caused by mutations in the transcription factor LMX1B. Renal-limited forms of this disease, termed nail-patella-like renal disease (NPLRD), and LMX1B nephropathy have recently been described. We report a large family, from the North East of England, with seven affected members with varying phenotypes of renal disease, ranging from ESRD at 28 years of age to microscopic haematuria and proteinuria and relatively preserved renal function. In this family, there were no extra-renal manifestations to suggest NPS. Genome-wide linkage studies and inheritance by descent (IBD) suggested disease loci on Chromosome 1 and 9. Whole exome sequencing (WES) analysis identified a novel sequence variant (p.R249Q) in the LMX1B gene in each of the three samples submitted, which was confirmed using Sanger sequencing. The variant segregated with the disease in all affected individuals. In silico modelling revealed that R249 is putatively located in close proximity to the DNA phosphoskeleton, supporting a role for this residue in the interaction between the LMX1B homeodomain and its target DNA. WES and analysis of potential target genes, including CD2AP, NPHS2, COL4A3, COL4A4 and COL4A5, did not reveal any co-inherited pathogenic variants. In conclusion, we confirm a novel LMX1B mutation in a large family with an autosomal dominant pattern of nephropathy. This report confirms that LMX1B mutations may cause a glomerulopathy without extra-renal manifestations. A molecular genetic diagnosis of LMX1B nephropathy thus provides a definitive diagnosis, prevents the need for renal biopsies and allows at risk family members to be screened.
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Affiliation(s)
- Noel Edwards
- Institute of Genetic Medicine , International Centre for Life, Newcastle University , Newcastle upon Tyne , UK ; Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Framlington Place , Newcastle University , Newcastle upon Tyne , UK
| | - Sarah J Rice
- Institute of Genetic Medicine , International Centre for Life, Newcastle University , Newcastle upon Tyne , UK ; Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Framlington Place , Newcastle University , Newcastle upon Tyne , UK
| | - Shreya Raman
- Royal Victoria Infirmary , Newcastle upon Tyne NHS Hospitals Foundation Trust , Newcastle upon Tyne , UK
| | - Ann Marie Hynes
- Institute of Genetic Medicine , International Centre for Life, Newcastle University , Newcastle upon Tyne , UK
| | - Shalabh Srivastava
- Institute of Genetic Medicine , International Centre for Life, Newcastle University , Newcastle upon Tyne , UK
| | - Iain Moore
- Renal Unit , Sunderland Royal Infirmary , Sunderland , UK
| | - Mohamed Al-Hamed
- Institute of Genetic Medicine , International Centre for Life, Newcastle University , Newcastle upon Tyne , UK
| | - Yaobo Xu
- Institute of Genetic Medicine , International Centre for Life, Newcastle University , Newcastle upon Tyne , UK
| | - Mauro Santibanez-Koref
- Institute of Genetic Medicine , International Centre for Life, Newcastle University , Newcastle upon Tyne , UK
| | - David T Thwaites
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Framlington Place , Newcastle University , Newcastle upon Tyne , UK
| | - Daniel P Gale
- UCL Centre for Nephrology , Royal Free Hospital , London , UK
| | - John A Sayer
- Institute of Genetic Medicine , International Centre for Life, Newcastle University , Newcastle upon Tyne , UK
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27
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Wang J, Zhang DF, Sun YM, Li RG, Qiu XB, Qu XK, Liu X, Fang WY, Yang YQ. NKX2-6 mutation predisposes to familial atrial fibrillation. Int J Mol Med 2014; 34:1581-90. [PMID: 25319568 DOI: 10.3892/ijmm.2014.1971] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Accepted: 10/10/2014] [Indexed: 12/29/2022] Open
Abstract
Atrial fibrillation (AF) is the most common form of sustained cardiac arrhythmia and is associated with substantially increased morbidity and mortality rates. Aggregating evidence demonstrates that genetic defects are involved in the pathogenesis of AF and a number of AF-associated genes have been identified. Nevertheless, AF is a genetically heterogeneous disorder and the genetic components underpinning AF in an overwhelming majority of patients remain unclear. In this study, the entire coding exons and splice junction sites of the NK2 homeobox 6 (NKX2-6) gene, which encodes a homeodomain transcription factor important for cardiovascular development, were sequenced in 150 unrelated patients with lone AF, and a novel heterozygous NKX2-6 mutation, p.Q175H, was identified in an index patient. Genetic analysis of the available family members of the mutation carrier revealed that the mutation co-segregated with AF transmitted in an autosomal dominant pattern. The missense mutation was absent in the 200 unrelated ethnically matched healthy individuals used as controls and the altered amino acid was completely conserved evolutionarily among species. Due to unknown transcriptional targets of NKX2-6, the functional characteristics of the mutation as regards transcriptional activity were analyzed using NKX2-5 as a surrogate. Alignment between human NKX2-6 and NKX2-5 proteins displayed that the Q175H-mutant NKX2-6 was equivalent to the Q181H-mutant NKX2-5, and the introduction of Q181H into NKX2-5 significantly decreased its transcriptional activity at the atrial natriuretic factor promoter. The present study firstly associates genetically defective NKX2-6 with enhanced susceptibility to AF, providing novel insight into the molecular mechanisms underlying AF and suggesting potential strategies for the antenatal prophylaxis and personalized treatment of AF.
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Affiliation(s)
- Jun Wang
- Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai 200120, P.R. China
| | - Dai-Fu Zhang
- Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai 200120, P.R. China
| | - Yu-Min Sun
- Department of Cardiology, Jing-An District Central Hospital, Shanghai 200040, P.R. China
| | - Ruo-Gu Li
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai 200030, P.R. China
| | - Xing-Biao Qiu
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai 200030, P.R. China
| | - Xin-Kai Qu
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai 200030, P.R. China
| | - Xu Liu
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai 200030, P.R. China
| | - Wei-Yi Fang
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai 200030, P.R. China
| | - Yi-Qing Yang
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai 200030, P.R. China
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28
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Ashraf H, Pradhan L, Chang EI, Terada R, Ryan NJ, Briggs LE, Chowdhury R, Zárate MA, Sugi Y, Nam HJ, Benson DW, Anderson RH, Kasahara H. A mouse model of human congenital heart disease: high incidence of diverse cardiac anomalies and ventricular noncompaction produced by heterozygous Nkx2-5 homeodomain missense mutation. ACTA ACUST UNITED AC 2014; 7:423-433. [PMID: 25028484 DOI: 10.1161/circgenetics.113.000281] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Heterozygous human mutations of NKX2-5 are highly penetrant and associated with varied congenital heart defects. The heterozygous knockout of murine Nkx2-5, in contrast, manifests less profound cardiac malformations, with low disease penetrance. We sought to study this apparent discrepancy between human and mouse genetics. Because missense mutations in the NKX2-5 homeodomain (DNA-binding domain) are the most frequently reported type of human mutation, we replicated this genetic defect in a murine knockin model. METHODS AND RESULTS We generated a murine model in a 129/Sv genetic background by knocking-in an Nkx2-5 homeodomain missense mutation previously identified in humans. The mutation was located at homeodomain position 52Arg→Gly (R52G). All the heterozygous neonatal Nkx2-5(+/R52G) mice demonstrated a prominent trabecular layer in the ventricular wall, so called noncompaction, along with diverse cardiac anomalies, including atrioventricular septal defects, Ebstein malformation of the tricuspid valve, and perimembranous and muscular ventricular septal defects. In addition, P10 Nkx2-5(+/R52G) mice demonstrated atrial sepal anomalies, with significant increase in the size of the interatrial communication and fossa ovalis, and decrease in the length of the flap valve compared with control Nkx2-5(+/+) or Nkx2-5(+/-) mice. CONCLUSIONS The results of our study demonstrate that heterozygous missense mutation in the murine Nkx2-5 homeodomain (R52G) is highly penetrant and result in pleiotropic cardiac effects. Thus, in contrast to heterozygous Nkx2-5 knockout mice, the effects of the heterozygous knockin mimic findings in humans with heterozygous missense mutation in NKX2-5 homeodomain.
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Affiliation(s)
- Hassan Ashraf
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville, FL 32610
| | - Lagnajeet Pradhan
- Department of Bioengineering, University of Texas at Dallas, TX 75080
| | - Eileen I Chang
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville, FL 32610
| | - Ryota Terada
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville, FL 32610
| | - Nicole J Ryan
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville, FL 32610
| | - Laura E Briggs
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville, FL 32610
| | - Rajib Chowdhury
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville, FL 32610
| | - Miguel A Zárate
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville, FL 32610
| | - Yukiko Sugi
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425
| | - Hyun-Joo Nam
- Department of Bioengineering, University of Texas at Dallas, TX 75080
| | - D Woodrow Benson
- Department of Pediatrics, Herma Heart Center, Medical College of Wisconsin, Milwaukee, WI 53226
| | | | - Hideko Kasahara
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, Gainesville, FL 32610
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29
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Ramakrishnan K, Ray P, Okkema PG. CEH-28 activates dbl-1 expression and TGF-β signaling in the C. elegans M4 neuron. Dev Biol 2014; 390:149-59. [PMID: 24690231 PMCID: PMC4023489 DOI: 10.1016/j.ydbio.2014.03.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 03/22/2014] [Accepted: 03/24/2014] [Indexed: 02/07/2023]
Abstract
M4 is a multifunctional neuron in the Caenorhabditis elegans pharynx that can both stimulate peristaltic contractions of the muscles in the pharyngeal isthmus and function systemically to regulate an enhanced sensory response under hypoxic conditions. Here we identify a third function for M4 that depends on activation of the TGF-β family gene dbl-1 by the homeodomain transcription factor CEH-28. dbl-1 is expressed in M4 and a subset of other neurons, and we show CEH-28 specifically activates dbl-1 expression in M4. Characterization of the dbl-1 promoter indicates that CEH-28 targets an M4-specific enhancer within the dbl-1 promoter region, while expression in other neurons is mediated by separate regulatory sequences. Unlike ceh-28 mutants, dbl-1 mutants do not exhibit M4 synaptic and signaling defects. Instead, both ceh-28 and dbl-1 mutants exhibit morphological defects in the g1 gland cells located adjacent to M4 in the pharynx, and these defects can be partially rescued by M4-specific expression of dbl-1 in these mutants. Identical gland cell defects are observed in sma-6 and daf-4 mutants defective in the receptor for DBL-1, but they are not observed in sma-2 and sma-3 mutants lacking the R-Smads functioning downstream of this receptor. Together these results identify a novel neuroendocrine function for M4 and provide evidence for an R-Smad-independent mechanism for DBL-1 signaling in C. elegans.
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Affiliation(s)
- Kalpana Ramakrishnan
- Department of Biological Sciences, University of Illinois at Chicago, 900 S. Ashland Avenue (MC567), Chicago, IL 60607, USA
| | - Paramita Ray
- Department of Biological Sciences, University of Illinois at Chicago, 900 S. Ashland Avenue (MC567), Chicago, IL 60607, USA
| | - Peter G Okkema
- Department of Biological Sciences, University of Illinois at Chicago, 900 S. Ashland Avenue (MC567), Chicago, IL 60607, USA.
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30
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Pröpper K, Meindl K, Sammito M, Dittrich B, Sheldrick GM, Pohl E, Usón I. Structure solution of DNA-binding proteins and complexes with ARCIMBOLDO libraries. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:1743-57. [PMID: 24914984 PMCID: PMC4051508 DOI: 10.1107/s1399004714007603] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 04/04/2014] [Indexed: 11/11/2022]
Abstract
Protein-DNA interactions play a major role in all aspects of genetic activity within an organism, such as transcription, packaging, rearrangement, replication and repair. The molecular detail of protein-DNA interactions can be best visualized through crystallography, and structures emphasizing insight into the principles of binding and base-sequence recognition are essential to understanding the subtleties of the underlying mechanisms. An increasing number of high-quality DNA-binding protein structure determinations have been witnessed despite the fact that the crystallographic particularities of nucleic acids tend to pose specific challenges to methods primarily developed for proteins. Crystallographic structure solution of protein-DNA complexes therefore remains a challenging area that is in need of optimized experimental and computational methods. The potential of the structure-solution program ARCIMBOLDO for the solution of protein-DNA complexes has therefore been assessed. The method is based on the combination of locating small, very accurate fragments using the program Phaser and density modification with the program SHELXE. Whereas for typical proteins main-chain α-helices provide the ideal, almost ubiquitous, small fragments to start searches, in the case of DNA complexes the binding motifs and DNA double helix constitute suitable search fragments. The aim of this work is to provide an effective library of search fragments as well as to determine the optimal ARCIMBOLDO strategy for the solution of this class of structures.
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Affiliation(s)
- Kevin Pröpper
- University of Göttingen, Germany
- Instituto de Biologia Molecular de Barcelona (IBMB-CSIC), Spain
| | - Kathrin Meindl
- Instituto de Biologia Molecular de Barcelona (IBMB-CSIC), Spain
| | - Massimo Sammito
- Instituto de Biologia Molecular de Barcelona (IBMB-CSIC), Spain
| | | | | | | | - Isabel Usón
- Instituto de Biologia Molecular de Barcelona (IBMB-CSIC), Spain
- Institucio Catalana de Recerca i Estudis Avancats (ICREA), Spain
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31
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Pradhan L, Gopal S, Nam HJ. Crystallization and preliminary X-ray analysis of the cardiac transcription factor complex of NKX2.5 and TBX5 with DNA. Acta Crystallogr F Struct Biol Commun 2014; 70:592-5. [PMID: 24817716 PMCID: PMC4014325 DOI: 10.1107/s2053230x14006761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2014] [Accepted: 03/26/2014] [Indexed: 11/10/2022] Open
Abstract
Heart development depends on timely expression of genes regulated by combinatorial interactions of master cardiac transcription factors. To elucidate the molecular basis of their interactions, a ternary complex of cardiac transcription factors, NKX2.5 and TBX5, and their target DNA was studied using X-ray crystallography. Here, the purification, crystallization and preliminary X-ray crystallographic analyses of the NKX2.5 homeodomain and TBX5 DNA-binding domain complex with a DNA element from the -252 promoter region of the atrial natriuretic factor are reported. The crystal diffracted to 2.88 Å resolution and belonged to space group P21, with unit-cell parameters a = 69.30, b = 77.78, c = 77.60 Å, β = 108.31°. Two sets of ternary complexes are present in an asymmetric unit with a solvent content of 54%.
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Affiliation(s)
- Lagnajeet Pradhan
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA
| | - Sunil Gopal
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA
| | - Hyun-Joo Nam
- Department of Bioengineering, University of Texas at Dallas, Richardson, TX 75080, USA
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32
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Yu H, Xu JH, Song HM, Zhao L, Xu WJ, Wang J, Li RG, Xu L, Jiang WF, Qiu XB, Jiang JQ, Qu XK, Liu X, Fang WY, Jiang JF, Yang YQ. Mutational spectrum of the NKX2-5 gene in patients with lone atrial fibrillation. Int J Med Sci 2014; 11:554-63. [PMID: 24782644 PMCID: PMC4003540 DOI: 10.7150/ijms.8407] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Accepted: 03/07/2014] [Indexed: 12/16/2022] Open
Abstract
Atrial fibrillation (AF) is the most common form of sustained cardiac arrhythmia in humans and is responsible for substantial morbidity and mortality worldwide. Emerging evidence indicates that abnormal cardiovascular development is involved in the pathogenesis of AF. In this study, the coding exons and splice sites of the NKX2-5 gene, which encodes a homeodomain-containing transcription factor essential for cardiovascular genesis, were sequenced in 146 unrelated patients with lone AF as well as the available relatives of the mutation carriers. A total of 700 unrelated ethnically matched healthy individuals used as controls were genotyped. The disease-causing potential of the identified NKX2-5 variations was predicted by MutationTaster and PolyPhen-2. The functional characteristics of the mutant NKX2-5 proteins were analyzed using a dual-luciferase reporter assay system. As a result, two heterozygous NKX2-5 mutations, including a previously reported p.E21Q and a novel p.T180A mutation, were identified in two families with AF transmitted in an autosomal dominant pattern. The mutations co-segregated with AF in the families with complete penetrance. The detected substitutions, which altered the amino acids highly conserved evolutionarily across species, were absent in 700 control individuals and were both predicted to be causative. Functional analyses demonstrated that the NKX2-5 mutants were associated with significantly decreased transcriptional activity compared with their wild-type counterpart. The findings expand the spectrum of NKX2-5 mutations linked to AF and provide additional evidence that dysfunctional NKX2-5 may confer vulnerability to AF, suggesting the potential benefit for the early prophylaxis and personalized treatment of AF.
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Affiliation(s)
- Hong Yu
- 1. Department of Cardiology, Tongji Hospital, Tongji University School of Medicine, 389 Xincun Road, Shanghai 200065, China
| | - Jia-Hong Xu
- 1. Department of Cardiology, Tongji Hospital, Tongji University School of Medicine, 389 Xincun Road, Shanghai 200065, China
| | - Hao-Ming Song
- 1. Department of Cardiology, Tongji Hospital, Tongji University School of Medicine, 389 Xincun Road, Shanghai 200065, China
| | - Lan Zhao
- 2. Department of Cardiology, Yantaishan Hospital, 91 Jiefang Road, Yantai 264001, Shandong, China
| | - Wen-Jun Xu
- 1. Department of Cardiology, Tongji Hospital, Tongji University School of Medicine, 389 Xincun Road, Shanghai 200065, China
| | - Juan Wang
- 1. Department of Cardiology, Tongji Hospital, Tongji University School of Medicine, 389 Xincun Road, Shanghai 200065, China
| | - Ruo-Gu Li
- 3. Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, 241 West Huaihai Road, Shanghai 200030, China
| | - Lei Xu
- 3. Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, 241 West Huaihai Road, Shanghai 200030, China
| | - Wei-Feng Jiang
- 3. Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, 241 West Huaihai Road, Shanghai 200030, China
| | - Xing-Biao Qiu
- 3. Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, 241 West Huaihai Road, Shanghai 200030, China
| | - Jin-Qi Jiang
- 4. Department of Emergency, Shanghai Chest Hospital, Shanghai Jiao Tong University, 241 West Huaihai Road, Shanghai 200030, China
| | - Xin-Kai Qu
- 3. Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, 241 West Huaihai Road, Shanghai 200030, China
| | - Xu Liu
- 3. Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, 241 West Huaihai Road, Shanghai 200030, China
| | - Wei-Yi Fang
- 3. Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, 241 West Huaihai Road, Shanghai 200030, China
| | - Jin-Fa Jiang
- 1. Department of Cardiology, Tongji Hospital, Tongji University School of Medicine, 389 Xincun Road, Shanghai 200065, China
| | - Yi-Qing Yang
- 3. Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, 241 West Huaihai Road, Shanghai 200030, China; ; 5. Department of Cardiovascular Research Laboratory, Shanghai Chest Hospital, Shanghai Jiao Tong University, 241 West Huaihai Road, Shanghai 200030, China; ; 6. Department of Central Laboratory, Shanghai Chest Hospital, Shanghai Jiao Tong University, 241 West Huaihai Road, Shanghai 200030, China
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Xie WH, Chang C, Xu YJ, Li RG, Qu XK, Fang WY, Liu X, Yang YQ. Prevalence and spectrum of Nkx2.5 mutations associated with idiopathic atrial fibrillation. Clinics (Sao Paulo) 2013; 68:777-84. [PMID: 23778487 PMCID: PMC3674279 DOI: 10.6061/clinics/2013(06)09] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/25/2012] [Accepted: 02/13/2013] [Indexed: 12/14/2022] Open
Abstract
OBJECTIVE The aim of this study was to evaluate the prevalence and spectrum of Nkx2.5 mutations associated with idiopathic atrial fibrillation (AF). METHODS A cohort of 136 unrelated patients with idiopathic atrial fibrillation and 200 unrelated, ethnically matched healthy controls were enrolled. The coding exons and splice junctions of the Nkx2.5 gene were sequenced in 136 atrial fibrillation patients, and the available relatives of mutation carriers and 200 controls were subsequently genotyped for the identified mutations. The functional characteristics of the mutated Nkx2.5 gene were analyzed using a dual-luciferase reporter assay system. RESULTS Two novel heterozygous Nkx2.5 mutations (p.N19D and p.F186S) were identified in 2 of the 136 unrelated atrial fibrillation cases, with a mutational prevalence of approximately 1.47%. These missense mutations co-segregated with atrial fibrillation in the families and were absent in the 400 control chromosomes. Notably, 2 mutation carriers also had congenital atrial septal defects and atrioventricular block. Multiple alignments of the Nkx2.5 protein sequences across various species revealed that the altered amino acids were completely conserved evolutionarily. Functional analysis demonstrated that the mutant Nkx2.5 proteins were associated with significantly reduced transcriptional activity compared to their wild-type counterpart. CONCLUSION These findings associate the Nkx2.5 loss-of-function mutation with atrial fibrillation and atrioventricular block and provide novel insights into the molecular mechanism involved in the pathogenesis of atrial fibrillation. These results also have potential implications for early prophylaxis and allele-specific therapy of this common arrhythmia.
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Affiliation(s)
- Wen-Hui Xie
- Shanghai Jiao Tong University School of Medicine, Shanghai Chest Hospital, Department of Nuclear Medicine, Shanghai 200030, China
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Costa MW, Guo G, Wolstein O, Vale M, Castro ML, Wang L, Otway R, Riek P, Cochrane N, Furtado M, Semsarian C, Weintraub RG, Yeoh T, Hayward C, Keogh A, Macdonald P, Feneley M, Graham RM, Seidman JG, Seidman CE, Rosenthal N, Fatkin D, Harvey RP. Functional characterization of a novel mutation in NKX2-5 associated with congenital heart disease and adult-onset cardiomyopathy. ACTA ACUST UNITED AC 2013; 6:238-47. [PMID: 23661673 DOI: 10.1161/circgenetics.113.000057] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND The transcription factor NKX2-5 is crucial for heart development, and mutations in this gene have been implicated in diverse congenital heart diseases and conduction defects in mouse models and humans. Whether NKX2-5 mutations have a role in adult-onset heart disease is unknown. METHODS AND RESULTS Mutation screening was performed in 220 probands with adult-onset dilated cardiomyopathy. Six NKX2-5 coding sequence variants were identified, including 3 nonsynonymous variants. A novel heterozygous mutation, I184M, located within the NKX2-5 homeodomain, was identified in 1 family. A subset of family members had congenital heart disease, but there was an unexpectedly high prevalence of dilated cardiomyopathy. Functional analysis of I184M in vitro demonstrated a striking increase in protein expression when transfected into COS-7 cells or HL-1 cardiomyocytes because of reduced degradation by the Ubiquitin-proteasome system. In functional assays, DNA-binding activity of I184M was reduced, resulting in impaired activation of target genes despite increased expression levels of mutant protein. CONCLUSIONS Certain NKX2-5 homeodomain mutations show abnormal protein degradation via the Ubiquitin-proteasome system and partially impaired transcriptional activity. We propose that this class of mutation can impair heart development and mature heart function and contribute to NKX2-5-related cardiomyopathies with graded severity.
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Affiliation(s)
- Mauro W Costa
- Developmental and Stem Cell Biology Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia.
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A novel NKX2.5 loss-of-function mutation responsible for familial atrial fibrillation. Int J Mol Med 2013; 31:1119-26. [PMID: 23525379 DOI: 10.3892/ijmm.2013.1316] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 02/27/2013] [Indexed: 01/08/2023] Open
Abstract
Atrial fibrillation (AF) represents the most common form of sustained cardiac arrhythmia and accounts for substantial morbidity and mortality. Increasing evidence demonstrates that abnormal cardiovascular development is involved in the pathogenesis of AF. In this study, the coding exons and splice sites of the NKX2.5 gene, which encodes a homeodomain-containing transcription factor pivotal for normal cardiovascular morphogenesis, were sequenced in 110 unrelated index patients with familial AF. The available relatives of the mutation carrier and 200 unrelated ethnically-matched healthy individuals serving as controls were subsequently genotyped. The disease-causing potential of the identified NKX2.5 variation was predicted by MutationTaster. The functional characteristics of the mutant NKX2.5 protein were analyzed using a dual-luciferase reporter assay system. As a result, a novel heterozygous NKX2.5 mutation, p.F145S, was identified in a family with AF transmitted as an autosomal dominant trait, which co-segregated with AF in the family with complete penetrance. The detected substitution, which altered the amino acid completely conserved evolutionarily across species, was absent in 400 control chromosomes and was automatically predicted to be causative. Functional analysis demonstrated that the NKX2.5 mutant was associated with significantly decreased transcriptional activity compared with its wild-type counterpart. To the best of our knowledge, this is the first report on the association of the NKX2.5 loss-of-function mutation with increased susceptibility to familial AF. The findings of the present study provide novel insights into the molecular mechanism underlying AF, suggesting the potential implications for the early prophylaxis and allele-specific therapy of AF.
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