Molecular Genetics of Congenital Heart Disease
1999; Lippincott Williams & Wilkins; Volume: 84; Issue: 2 Linguagem: Inglês
10.1161/01.res.84.2.247
ISSN1524-4571
AutoresStefano Schiaffino, Bruno Dallapiccola, Raffaella Di Lisi,
Tópico(s)Genomic variations and chromosomal abnormalities
ResumoHomeCirculation ResearchVol. 84, No. 2Molecular Genetics of Congenital Heart Disease Free AccessEditorialPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessEditorialPDF/EPUBMolecular Genetics of Congenital Heart Disease A Problem of Faulty Septation Stefano Schiaffino, Bruno Dallapiccola and Raffaella Di Lisi Stefano SchiaffinoStefano Schiaffino From the Department of Biomedical Sciences and CNR Center of Muscle Biology and Physiopathology (S.S., R.D.L.), University of Padova; and Department of Public Health and Cell Biology (B.D.), Tor Vergata University, Rome, Italy. , Bruno DallapiccolaBruno Dallapiccola From the Department of Biomedical Sciences and CNR Center of Muscle Biology and Physiopathology (S.S., R.D.L.), University of Padova; and Department of Public Health and Cell Biology (B.D.), Tor Vergata University, Rome, Italy. and Raffaella Di LisiRaffaella Di Lisi From the Department of Biomedical Sciences and CNR Center of Muscle Biology and Physiopathology (S.S., R.D.L.), University of Padova; and Department of Public Health and Cell Biology (B.D.), Tor Vergata University, Rome, Italy. Originally published5 Feb 1999https://doi.org/10.1161/01.RES.84.2.247Circulation Research. 1999;84:247–249The transition from the single circulation of the embryo to the double circulation of the neonatal and adult heart involves the transformation of the primitive heart tube through a complex morphogenetic process, resulting in completely separated right and left heart chambers and distinct pulmonary and systemic circulations. Septation of heart chambers starts at early stages in embryogenesis and is completed only at birth with the closure of the foramen ovale. Defects in heart septation, including atrial septal defects, atrioventricular canal septal defects, ventricular septal defects, and conotruncal septal defects, represent a major cause of congenital heart disease. The molecular basis of faulty heart septation is now the object of intensive investigation.Mutant genes coding for 2 transcription factors, TBX5 and NKX2.5, have been recently identified by positional cloning in families with high incidence of atrial or ventricular septal defects. Mutations of the TBX5 gene cause the Holt-Oram syndrome, a developmental disorder affecting the heart and the upper limb, the most frequent cardiac abnormalities being atrial and/or ventricular septal defects and conduction defects.12 Mutations of the homeobox transcription factor NKX2.5 cause nonsyndromic congenital heart disease, in particular, atrial septal defects and atrioventricular node dysfunction.3 Most mutations so far identified in the TBX5 and NKX2.5 genes induce the formation of truncated proteins resulting in haploinsufficiency. On the other hand, the atrioventricular canal septal defects frequently associated with Down syndrome are probably due to gene overexpression rather than deficiency, namely the presence of 3 copies of chromosome 21 genes. The study of rare patients with partial chromosome 21 trisomy and atrioventricular canal septal defects has allowed the definition of a 2.5-Mb critical region at 21q22.2-q22.3, which is responsible for cardiac malformations: this region should therefore contain one or more genes whose overexpression interferes with correct atrioventricular canal septation.4 Progress in disease gene discovery can be accelerated by the convergence of basic research in flies and mice with human molecular genetics. The role of the NKX2.5 gene in congenital heart disease is a case in point. A gene called tinman is essential for the development of the heart in Drosophila, and the inactivation of a murine homolog of tinman, Nkx2.5, causes arrested development of the primitive heart tube.5 The human NKX2.5 gene maps to chromosome 5q35 and when a locus in the very same position was mapped by linkage analysis in families with a high incidence of atrial septal defects, the NKX2.5 gene was an obvious candidate, and mutations of this gene were rapidly identified.The chick embryo is also a powerful model to identify candidate genes responsible for congenital heart disease, because experimental manipulations such as transplanting and backtransplanting specific tissues are feasible in the chick but not in the mammalian embryo. In this issue of Circulation Research, Margaret Kirby and her coworkers have made clever use of the chick embryo system to explore the role of Hira, a candidate gene for the DiGeorge syndrome (DGS), and the velocardiofacial syndrome (VCFS), in outflow septation.6Outflow Septation, Neural Crest, and DiGeorge SyndromeSeptation of the outflow tract (conotruncus) with separation of the aorta and pulmonary trunk is an especially complex process because it requires, in addition to the intrinsic components of the heart tube, endocardium and myocardium, an extracardiac population of neural crest cells that migrate from the rostral neural folds to the pharyngeal arches and finally to the cardiac outflow tract. Ablation of the neural crest in chick embryos leads to an undivided outflow vessel (persistent truncus arteriosus or common arterial trunk) overriding a ventricular septal defect or originating from the right ventricle.7 These malformations are reminiscent of those found in DGS and VCFS, 2 human genetic diseases with overlapping phenotypic features and wide variability in the clinical spectrum. The clinical picture of DGS includes, in addition to conotruncal defects, hypoplasia of the thymus and parathyroid glands and mildly dysmorphic facial features, namely malformations of structures derived from the neural crest and known to be altered after ablation of the neural crest in chick embryos, reinforcing the view that DGS is a neural crest disease.8Most DGS and VCFS patients have microdeletions of chromosomal region 22q11, generally undetectable by standard karyotypic analysis but detectable by fluorescent in situ hybridization on metaphase chromosomes.89 Congenital conotruncal defects should therefore result from haploinsufficiency of one or more genes present in chromosome 22q11 and involved in cardiac neural crest function. The region deleted in the majority of patients is large (about 3 Mb) and contains more than 20 genes, but the study of patients with translocations or particularly small microdeletions has allowed the identification of a 250-kb minimal critical region that is deleted in most DGS patients. However, some patients with typical DGS phenotype show deletion of distinct, nonoverlapping regions. Because there is no evidence for a single large gene that may be disrupted in the different patients, it seems more likely that DGS is caused by the deficiency of multiple genes and/or regulatory elements controlling multiple genes, similar to the "locus control regions" that regulate other gene clusters.8910 Many genes in the critical region have been completely sequenced; however, no specific mutation has been detected in DGS/VCFS patients without any obvious deletion. A balanced translocation associated with DGS in a patient and with VCFS in her mother was shown to disrupt 22q11 sequences that are transcribed but not translated, possibly associated with transcriptional control elements.11Is HIRA the Culprit Gene?The human HIRA gene is one of the most studied among the genes mapped to the DGS critical region. Insight into the role of this gene has come from studies on yeast, and, indeed, HIRA has been named after the yeast HIR (histone regulatory) genes, which act as repressors of histone gene transcription and are probably involved in the remodeling of chromatin structure.12 HIRA, a nuclear protein, is expressed in various embryonic tissues including the rostral neural crest and can bind histones as well as other histone-binding proteins.13 Interestingly, HIRA also interacts with Pax3, a transcription factor containing paired box and homeodomain elements.14 The Pax3 gene is disrupted in the splotch mutant mouse, which shows multiple defects in neural crest–derived tissues, including cardiac outflow tract, thymus, and parathyroids, namely a phenotype that closely resembles both DGS and neural crest ablation.15 However, loss of function mutations of the human PAX3 gene cause Waardenburg syndrome type 1, an autosomal dominant disease characterized by hearing loss and hypopigmentation but not cardiac defects, due to altered development of other neural crest subsets.Farrell et al6 now add direct evidence for a role of Hira in outflow tract remodeling. The region of neural folds containing the premigratory cardiac neural crest was explanted in chick embryos and treated in vitro with antisense oligonucleotides against chick Hira, then backtransplanted in the correct position into the same embryos, most of which were subsequently found to develop persistent truncus arteriosus. However, attenuation of Hira expression did not reproduce all features of neural crest ablation, in particular, the patterning of aortic arch arteries was not affected, suggesting that additional genes are involved in DGS.Do these experiments provide definitive evidence for a role of HIRA in DGS? An advantage of the antisense approach, compared with gene targeting in the mouse, is that gene expression can be selectively attenuated in a specific tissue and a specific stage in development, thus avoiding the risk of pleiotropic effects secondary to gene disruption in many tissues. A potential problem with antisense experiments is that the degree of gene attenuation cannot be precisely controlled. In addition, given the dramatic effect of the Hira gene knockout on mouse embryonic development (see below) one wonders whether neural crest cells may be partially damaged by Hira gene inactivation so that the effect would be similar to a partial neural crest ablation experiment. A region homologous to that frequently deleted in DGS has been mapped on mouse chromosome 16 (Reference 16 ), and targeted inactivation of Hira has now been produced.17 The heterozygotes are apparently normal whereas the homozygotes die at about embryonic day 10, namely before cardiac neural crest immigration and outflow septation. The developmental delay and severe disorganization of the homozygote embryos indicate that this gene affects the development of many cell types, in keeping with its ubiquitous distribution in mouse embryonic tissues.18Searching for Other GenesThe 22q11 region commonly deleted in DGS/VCFS contains several genes coding for putative transcription factors, including GSCL, TBX1, ZNF74, and LZTR1. The mouse Gscl gene, which encodes a goosecoid-like homeodomain protein, has been inactivated; however, both heterozygotes and homozygotes are normal and do not exhibit any cardiac malformations similar to those seen in DGS.1920 A new gene called NLVCF, which contains a nuclear localization signal, has been mapped to 22q11.21 The rapid progress in the characterization of the various genes by use of either the antisense approach in chick embryos or the gene targeting approach in mice should clarify their role in DGS pathogenesis. However, it is possible that the DGS phenotype cannot be reproduced by disruption of a single gene but requires deletion of the whole group of contiguous genes. Mouse chromosome 16 regions corresponding to the human 22.q11 critical region can be deleted by chromosomal engineering using the Cre-LoxP system22 ; however, major rearrangements of their gene cluster have taken place during the divergence of mouse and human, leading to altered gene order.16Multiple genes in different chromosomal loci are certainly involved in the remodeling of the outflow tract, and their mutation can lead to phenotypes similar to DGS. In fact a number of cases of DGS/VCFS have no detectable deletion within 22q11 but deletion of another locus in chromosome 10p13-p14, suggesting that one or more genes present in this locus can also be responsible for these syndromes.2324 Targeted null mutations of different genes can induce conotruncal defects in the mouse. Some of these genes, such as the gene coding for the transcription factor Sox4, are expressed in the endocardium and gene targeting causes both common trunk and defective semilunar valve development.2526 Double mutations of retinoic acid receptors (RAR and RXR) affect neural crest development leading to conotruncal defects, as well as abnormalities in thymus, parathyroids, and craniofacial skeleton.27 The endothelin-mediated intercellular signaling has recently emerged as a major player in neural crest–dependent remodeling of the heart outflow tract: inactivation of endothelin-1 (ET-1), endothelin converting enzyme-1 (ECE-1), and endothelin receptor-A (ETA) genes produce similar phenotypes characterized by craniofacial and cardiac abnormalities, mainly in patterning of great vessels and conotruncal region, by affecting the postmigratory cardiac neural crest development.28293031 The role of endothelin signaling in heart morphogenesis has been confirmed by pharmacological experiments on chick embryos: embryos treated with ETA but not with ETB antagonists show heart and aortic arch derivative defects similar to those observed in mice after gene inactivation of ET-1 and ETA.32 A possible link between the endothelin signaling system and the transcription factors involved in neural crest and heart development is suggested by the finding that ET-1-null mice show markedly decreased expression of a basic helix-loop-helix transcription factor called dHAND, which is expressed in embryonic heart and pharyngeal arches and whose inactivation leads to abnormal development of neural crest–derived aortic arch arteries.33 A dHAND-dependent gene, expressed in the cardiac and craniofacial neural crest–derived mesenchyme, has been found to map to 22q11 (D. Srivastava, written communication, 1998). At the moment, there is no evidence for a role of these genes in human congenital heart disease; however, the identification of the regulatory circuits involved in heart development will be essential for a better understanding not only of the relatively rare genetic syndromes such as DGS/VCFS but also of the more common nonsyndromic cardiac malformations which are still mostly unexplained.The opinions expressed in this editorial are not necessarily those of the editors or of the American Heart Association.FootnotesCorrespondence to Stefano Schiaffino, Department of Biomedical Sciences and CNR Center of Muscle Biology and Physiopathology, University of Padova, Viale G. Colombo 3, 35121 Padova, Italy. E-mail [email protected] References 1 Li Q, Newbury-Ecob R, Terrett J, Wilson D, Curtis A, Yi C, Gebuhr T, Bullen P, Robson S, Strachan T, Bonnet D, Lyonnet S, Young I, Raeburn J, Buckler A, Law D, Brook J. Holt-Oram syndrome is caused by mutations in TBX5, a member of the Brachyury (T) gene family. Nat Genet.1997; 15:21–29.CrossrefMedlineGoogle Scholar2 Basson C, Bachinsky D, Lin R, Levi T, Elkins J, Soults J, Grayzel D, Kroumpouzou E, Traill T, Leblanc-Straceski J, Renault B, Kucherlapati R, Seidman J, Seidman C. Mutations in human TBX5 [corrected] cause limb and cardiac malformation in Holt-Oram syndrome. Nat Genet.1997; 15:30–35.CrossrefMedlineGoogle Scholar3 Schott J, Benson D, Basson C, Pease W, Silberbach G, Moak J, Maron B, Seidman C, Seidman J. Congenital heart disease caused by mutations in the transcription factor NKX2–5. Science.1998; 281:108–111.CrossrefMedlineGoogle Scholar4 Barlow G, Chen N, Mjaatvedt C, Pettenati M, Vekemans M, Koremberg J. Down syndrome: DS-CAM is as strong candidate for congenital heart disease. Am J Hum Genet. 1998;63(suppl):A7. Abstract.Google Scholar5 Harvey R. NK-2 homeobox genes and heart development. Dev Biol.1996; 178:203–216.CrossrefMedlineGoogle Scholar6 Farrell MJ, Stadt H, Wallis KT, Scambler P, Hixon RL, Wolfe R, Leatherbury L, Kirby ML. HIRA, a DiGeorge syndrome candidate gene, is required for cardiac outflow tract septation. Circ Res.1999; 84:127–135.CrossrefMedlineGoogle Scholar7 Kirby M, Waldo K. Neural crest and cardiovascular patterning. Circ Res.1995; 77:211–215.CrossrefMedlineGoogle Scholar8 Goldmuntz E, Emanuel B. Genetic disorders of cardiac morphogenesis. The DiGeorge and velocardiofacial syndromes. Circ Res.1997; 80:437–443.CrossrefMedlineGoogle Scholar9 Lindsay E, Baldini A. Congenital heart defects and 22q11 deletions: which genes count? Mol Med Today.1998; 4:350–357.CrossrefMedlineGoogle Scholar10 Dallapiccola B, Pizzuti A, Novelli G. How many breaks do we need to CATCH on 22q11? Am J Hum Genet.1996; 59:7–11.MedlineGoogle Scholar11 Sutherland H, Wadey R, McKie JM, Taylor C, Atif U, Johnstone KA, Halford S, Kim U-J, Goodship J, Baldini A, Scambler P. Identification of a novel transcript disrupted by a balanced translocation associated with DiGeorge syndrome. Am J Hum Genet.1996; 59:23–31.MedlineGoogle Scholar12 Lamour V, Lecluse Y, Desmaze C, Spector M, Bodescot M, Aurias A, Osley M, Lipinski M. A human homolog of the S. cerevisiae HIR1 and HIR2 transcriptional repressors cloned from the DiGeorge syndrome critical region. Hum Mol Genet.1995; 5:791–799.Google Scholar13 Lorain S, Quivy J, Monier-Gavelle F, Scamps C, Lecluse Y, Almouzni G, Lipinski M. Core histones and HIRIP3, a novel histone-binding protein, directly interact with WD repeat protein HIRA. Mol Cell Biol.1998; 18:5546–556.CrossrefMedlineGoogle Scholar14 Magnaghi P, Roberts C, Lorain S, Lipinski M, Scambler P. HIRA, a mammalian homologue of Saccharomyces cerevisiae transcriptional co-repressors, interacts with Pax3. Nat Genet.1998; 20:74–77.CrossrefMedlineGoogle Scholar15 Conway S, Henderson D, Copp A. Pax3 is required for cardiac neural crest migration in the mouse: evidence from the splotch (Sp2H) mutant. Development.1997; 24:505–514.Google Scholar16 Sutherland H, Kim U, Scambler P. Cloning and comparative mapping of the DiGeorge syndrome critical region in the mouse. Genomics.1998; 52:37–43.CrossrefMedlineGoogle Scholar17 Scambler P, Roberts C, Sutherland H, Kimber W, Lui V, Halford S, McKie J, Snoeren S, Lohman F, Meijers C, Wynshaw-Boris A. Hira, a gene from DGS/VCFS region, is required for normal embryogenesis. Am J Hum Genet. 1998;63(suppl):A7. Abstract.Google Scholar18 Wilming L, Snoeren C, van Rijswijk A, Grosveld F, Meijers C. The murine homologue of HIRA, a DiGeorge syndrome candidate gene, is expressed in embryonic structures in human CATCH22 patients. Hum Mol Genet.1997; 6:247–258.CrossrefMedlineGoogle Scholar19 Wakamiya M, Lindsay E, Rivera-Perez J, Baldini A, Behringer R. Functional analysis of gscl in the pathogenesis of the DiGeorge and velocardiofacial syndromes. Hum Mol Genet.1998; 7:1835–1840.CrossrefMedlineGoogle Scholar20 Saint-Jore B, Puech A, Heyer J, Lin Q, Raine C, Kucherlapati R, Skoultchi A. Goosecoid-like (Gscl), a candidate gene for velocardiofacial syndrome, is not essential for normal development. Hum Mol Genet.1998; 7:1814–1819.Google Scholar21 Funke B, Puech A, Saint-Jore B, Pandita R, Skoultchi A, Morrow B. Isolation and characterization of a human gene containing a nuclear localization signal from the critical region for velo-cardio-facial syndrome on 22q11. Genomics.1998; 53:146–154.CrossrefMedlineGoogle Scholar22 Ramirez-Solis R, Liu P, Bradley A. Chromosome engineering in mice. Nature.1995; 378:720–724.CrossrefMedlineGoogle Scholar23 Daw S, Taylor C, Kraman M, Call K, Mao J, Schuffenhauer S, Meitinger T, Lipson T, Goodship J, Scambler P. A common region of 10p deleted in DiGeorge and velocardiofacial syndromes. Nat Genet.1996;13:458–460.Google Scholar24 Schuffenhauer S, Lichtner P, Peykar-Derakhshandeh P, Murken J, Haas O, Back E, Wolff G, Zabel B, Barisic I, Rauch A, Borochowitz Z, Dallapiccola B, Ross M, Meitinger T. Deletion mapping on chromosome 10p and definition of a critical region for the second DiGeorge syndrome locus (DGS2). Eur J Hum Genet.1998; 6:213–225.CrossrefMedlineGoogle Scholar25 Schilham M, Oosterwegel M, Moerer P, Ya J, de Boer P, van de Wetering M, Verbeek S, Lamers W, Kruisbeek A, Cumano A, Clevers H. Defects in cardiac outflow tract formation and pro-B-lymphocyte expansion in mice lacking Sox-4. Nature.1996; 380:711–714.CrossrefMedlineGoogle Scholar26 Ya J, Schilham M, de Boer P, Moorman A, Clevers H, Lamers W. Sox4-deficiency syndrome in mice is an animal model for common trunk. Circ Res.1998; 83:986–994.CrossrefMedlineGoogle Scholar27 Ghyselinck N, Wendling O, Messaddeq N, Dierich A, Lampron C, Decimo D, Viville S, Chambon P, Mark M. Contribution of retinoic acid receptor beta isoforms to the formation of the conotruncal septum of the embryonic heart. Dev Biol.1998; 198:303–318.CrossrefMedlineGoogle Scholar28 Kurihara Y, Kurihara H, Oda H, Maemura K, Nagai R, Ishikawa T, Yazaki Y. Aortic arch malformations and ventricular septal defect in mice deficient in endothelin-1. J Clin Invest.1995; 96:293–300.CrossrefMedlineGoogle Scholar29 Clouthier D, Hosoda K, Richardson J, Williams S, Yanagisawa H, Kuwaki T, Kumada M, Hammer R, Yanagisawa M. Cranial and cardiac neural crest defects in endothelin-A receptor-deficient mice. Development.1998; 125:813–824.CrossrefMedlineGoogle Scholar30 Yanagisawa H, Hammer R, Richardson J, Williams S, Clouthier D, Yanagisawa M. Role of endothelin-1/endothelin-A receptor-mediated signaling pathway in the aortic arch patterning in mice. J Clin Invest.1998; 102:22–23.CrossrefMedlineGoogle Scholar31 Yanagisawa H, Yanagisawa M, Kapur R, Richardson J, Williams S, Clouthier D, de Wit D, Emoto N, Hammer R. Dual genetic pathways of endothelin-mediated intercellular signaling revealed by targeted disruption of endothelin converting enzyme-1 gene. Development.1998; 125:825–836.CrossrefMedlineGoogle Scholar32 Kempf H, Linares C, Corvol P, Gasc JM. Pharmacological inactivation of the endothelin type A receptor in the early chick embryo: a model of mispatterning of the branchial arch derivatives. Development.1998; 125:4931–4941.CrossrefMedlineGoogle Scholar33 Thomas T, Kurihara H, Yamagishi H, Kurihara Y, Yazaki Y, Olson E, Srivastava D. A signaling cascade involving endothelin-1, dHAND and msx1 regulates development of neural-crest-derived branchial arch mesenchyme. Development.1998; 125:3005–3014.CrossrefMedlineGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetailsCited By Lee C, Hsieh K, Chen Y and Shiue Y (2009) Identification of Candidate Genes for Congenital Ventricular Septal Defects With HSA22q11 Loss of Heterozygosity, Revista Española de Cardiología (English Edition), 10.1016/S1885-5857(09)71555-5, 62:3, (263-272), Online publication date: 1-Mar-2009. Lee C, Hsieh K, Chen Y and Shiue Y (2009) Identificación de genes candidatos en las comunicaciones interventriculares congénitas con pérdida de heterocigosis de HSA22q11, Revista Española de Cardiología, 10.1016/S0300-8932(09)70369-0, 62:3, (263-272), Online publication date: 1-Mar-2009. Khetyar M, Tinworth L, Syrris P, Abushaban L, Abdulazzaq Y, Silengo M, Carvalho J and Carter N (2008) NKX2.5/NKX2.6 Mutations Are Not a Common Cause of Isolated Type 1 Truncus Arteriosus in a Small Cohort of Multiethnic Cases , Genetic Testing, 10.1089/gte.2007.0122, 12:4, (467-469), Online publication date: 1-Dec-2008. Boot M, Gittenberger-De Groot A, Van Iperen L, Hierck B and Poelmann R (2003) Spatiotemporally separated cardiac neural crest subpopulations that target the outflow tract septum and pharyngeal arch arteries, The Anatomical Record, 10.1002/ar.a.10099, 275A:1, (1009-1018), Online publication date: 1-Nov-2003. Sun G, Yuen Chan S, Yuan Y, Wang Chan K, Qiu G, Sun K and Ping Leung M (2002) Isolation of differentially expressed genes in human heart tissues, Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, 10.1016/S0925-4439(02)00171-0, 1588:3, (241-246), Online publication date: 1-Dec-2002. February 5, 1999Vol 84, Issue 2 Advertisement Article InformationMetrics © 1999 American Heart Association, Inc.https://doi.org/10.1161/01.RES.84.2.247 Originally publishedFebruary 5, 1999 KeywordsHIRAseptationneural crestDiGeorge syndromePDF download Advertisement
Referência(s)