51
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Cessans C, Ehlinger V, Arnaud C, Yart A, Capri Y, Barat P, Cammas B, Lacombe D, Coutant R, David A, Baron S, Weill J, Leheup B, Nicolino M, Salles JP, Verloes A, Tauber M, Cavé H, Edouard T. Growth patterns of patients with Noonan syndrome: correlation with age and genotype. Eur J Endocrinol 2016; 174:641-50. [PMID: 26903553 DOI: 10.1530/eje-15-0922] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 02/22/2016] [Indexed: 12/22/2022]
Abstract
BACKGROUND Growth patterns of patients with Noonan syndrome (NS) were established before the involved genes were identified. OBJECTIVE The goal of this study was to compare growth parameters according to genotype in patients with NS. SUBJECTS AND METHODS The study population included 420 patients (176 females and 244 males) harboring mutations in the PTPN11, SOS1, RAF1, or KRAS genes. NS-associated PTPN11 mutations (NS-PTPN11) and NS with multiple lentigines-associated PTPN11 mutations (NSML-PTPN11) were distinguished. Birth measures and height and body mass index (BMI) measures at 2, 5, 10 years, and adulthood were compared with the general population and between genotypes. RESULTS Patients with NS were shorter at birth (mean birth length standard deviation score (SDS): -1.0 ± 1.4; P < 0.001) and throughout childhood than the healthy population, with height SDS being -2.1 ± 1.3 at 2 years, and -2.1 ± 1.2 at 5 and 10 years and adulthood (P < 0.001). At birth, patients with NS-PTPN11 were significantly shorter and thinner than patients with NSML-PTPN11, SOS1, or KRAS. Growth retardation was significantly less severe and less frequent at 2 years in patients with NSML-PTPN11 and SOS1 than in patients with NS-PTPN11 (P < 0.001 and P = 0.002 respectively). Patients with NS had lower BMI at 10 years (P < 0.001). No difference between genotypes was demonstrated. CONCLUSION Determining the growth patterns of patients with NS according to genotype should better inform clinicians about the natural course of growth in NS so that they can optimize the follow-up and management of these patients.
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Affiliation(s)
- Catie Cessans
- EndocrineBone Diseases, and Genetics Unit, Children's Hospital, Toulouse University Hospital, Toulouse, France
| | - Virginie Ehlinger
- UMR 1027 INSERMUniversity of Toulouse Paul Sabatier, Toulouse, France
| | - Catherine Arnaud
- UMR 1027 INSERMUniversity of Toulouse Paul Sabatier, Toulouse, France Clinical Epidemiology UnitToulouse University Hospital, Toulouse, France
| | - Armelle Yart
- INSERM UMR 1048Institute of Cardiovascular and Metabolic Diseases (I2MC), University of Toulouse Paul Sabatier, Toulouse, France
| | - Yline Capri
- Departments of GeneticsRobert-Debré University Hospital, APHP, Paris, France
| | - Pascal Barat
- Pediatric Endocrinology DepartmentClinical investigation Centre (CIC 1401), Bordeaux University Hospital, Bordeaux, France
| | - Benoit Cammas
- Pediatric Endocrinology DepartmentClinical investigation Centre (CIC 1401), Bordeaux University Hospital, Bordeaux, France
| | - Didier Lacombe
- Genetics DepartmentBordeaux University Hospital, EA4576, Bordeaux, France
| | - Régis Coutant
- Pediatric Endocrinology DepartmentAngers University Hospital, Angers, France
| | - Albert David
- Genetics DepartmentNantes University Hospital, Nantes, France
| | - Sabine Baron
- Pediatric Endocrine UnitNantes University Hospital, Nantes, France
| | - Jacques Weill
- Pediatric Endocrine UnitLille University Hospital, Lille, France
| | - Bruno Leheup
- Pediatric and Genetics UnitNancy University Hospital, Vandoeuvre, France
| | - Marc Nicolino
- Pediatric Endocrinology DepartmentLyon University Pediatric Hospital, INSERM U.1060/UCBL/HCL, France
| | - Jean-Pierre Salles
- EndocrineBone Diseases, and Genetics Unit, Children's Hospital, Toulouse University Hospital, Toulouse, France INSERM UMR 1043Centre of Pathophysiology of Toulouse Purpan (CPTP), University of Toulouse Paul Sabatier, Toulouse, France
| | - Alain Verloes
- Departments of GeneticsRobert-Debré University Hospital, APHP, Paris, France
| | - Maithé Tauber
- EndocrineBone Diseases, and Genetics Unit, Children's Hospital, Toulouse University Hospital, Toulouse, France INSERM UMR 1043Centre of Pathophysiology of Toulouse Purpan (CPTP), University of Toulouse Paul Sabatier, Toulouse, France
| | - Hélène Cavé
- Departments of GeneticsRobert-Debré University Hospital, APHP, Paris, France
| | - Thomas Edouard
- EndocrineBone Diseases, and Genetics Unit, Children's Hospital, Toulouse University Hospital, Toulouse, France INSERM UMR 1043Centre of Pathophysiology of Toulouse Purpan (CPTP), University of Toulouse Paul Sabatier, Toulouse, France
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52
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Lee TM, Chung WK. Genetics and Hypertrophic Cardiomyopathy. CURRENT PEDIATRICS REPORTS 2016. [DOI: 10.1007/s40124-016-0097-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Jindal GA, Goyal Y, Burdine RD, Rauen KA, Shvartsman SY. RASopathies: unraveling mechanisms with animal models. Dis Model Mech 2016. [PMID: 26203125 PMCID: PMC4527292 DOI: 10.1242/dmm.020339] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
RASopathies are developmental disorders caused by germline mutations in the Ras-MAPK pathway, and are characterized by a broad spectrum of functional and morphological abnormalities. The high incidence of these disorders (∼1/1000 births) motivates the development of systematic approaches for their efficient diagnosis and potential treatment. Recent advances in genome sequencing have greatly facilitated the genotyping and discovery of mutations in affected individuals, but establishing the causal relationships between molecules and disease phenotypes is non-trivial and presents both technical and conceptual challenges. Here, we discuss how these challenges could be addressed using genetically modified model organisms that have been instrumental in delineating the Ras-MAPK pathway and its roles during development. Focusing on studies in mice, zebrafish and Drosophila, we provide an up-to-date review of animal models of RASopathies at the molecular and functional level. We also discuss how increasingly sophisticated techniques of genetic engineering can be used to rigorously connect changes in specific components of the Ras-MAPK pathway with observed functional and morphological phenotypes. Establishing these connections is essential for advancing our understanding of RASopathies and for devising rational strategies for their management and treatment. Summary: Developmental disorders caused by germline mutations in the Ras-MAPK pathway are called RASopathies. Studies with animal models, including mice, zebrafish and Drosophila, continue to enhance our understanding of these diseases.
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Affiliation(s)
- Granton A Jindal
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Yogesh Goyal
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Rebecca D Burdine
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Katherine A Rauen
- Department of Pediatrics, MIND Institute, Division of Genomic Medicine, University of California, Davis, Sacramento, CA 95817, USA
| | - Stanislav Y Shvartsman
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
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da Silva FM, Jorge AA, Malaquias A, da Costa Pereira A, Yamamoto GL, Kim CA, Bertola D. Nutritional aspects of Noonan syndrome and Noonan-related disorders. Am J Med Genet A 2016; 170:1525-31. [DOI: 10.1002/ajmg.a.37639] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 02/24/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Fernanda Marchetto da Silva
- Unidade de Genética do Instituto da Criança; Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo; São Paulo Brazil
| | - Alexander Augusto Jorge
- Endocrinologia; LIM/25; Faculdade de Medicina da Universidade de São Paulo; São Paulo Brazil
| | - Alexandra Malaquias
- Endocrinologia; LIM/25; Faculdade de Medicina da Universidade de São Paulo; São Paulo Brazil
| | - Alexandre da Costa Pereira
- Instituto do Coração; Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo; São Paulo Brazil
| | - Guilherme Lopes Yamamoto
- Unidade de Genética do Instituto da Criança; Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo; São Paulo Brazil
| | - Chong Ae Kim
- Unidade de Genética do Instituto da Criança; Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo; São Paulo Brazil
| | - Debora Bertola
- Unidade de Genética do Instituto da Criança; Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo; São Paulo Brazil
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55
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Recent advances in RASopathies. J Hum Genet 2015; 61:33-9. [PMID: 26446362 DOI: 10.1038/jhg.2015.114] [Citation(s) in RCA: 239] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 08/09/2015] [Accepted: 08/24/2015] [Indexed: 12/21/2022]
Abstract
RASopathies or RAS/mitogen-activated protein kinase (MAPK) syndromes are a group of phenotypically overlapping syndromes caused by germline mutations that encode components of the RAS/MAPK signaling pathway. These disorders include neurofibromatosis type I, Legius syndrome, Noonan syndrome, Noonan syndrome with multiple lentigines (formerly called LEOPARD syndrome), Costello syndrome, cardiofaciocutaneous (CFC) syndrome, Noonan-like syndrome, hereditary gingival fibromatosis and capillary malformation-arteriovenous malformation. Recently, novel gene variants, including RIT1, RRAS, RASA2, A2ML1, SOS2 and LZTR1, have been shown to be associated with RASopathies, further expanding the disease entity. Although further analysis will be needed, these findings will help to better elucidate an understanding of the pathogenesis of these disorders and will aid in the development of potential therapeutic approaches. In this review, we summarize the novel genes that have been reported to be associated with RASopathies and highlight the cardiovascular abnormalities that may arise in affected individuals.
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Goodwin AF, Kim R, Bush JO, Klein OD. From Bench to Bedside and Back: Improving Diagnosis and Treatment of Craniofacial Malformations Utilizing Animal Models. Curr Top Dev Biol 2015; 115:459-92. [PMID: 26589935 DOI: 10.1016/bs.ctdb.2015.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Craniofacial anomalies are among the most common birth defects and are associated with increased mortality and, in many cases, the need for lifelong treatment. Over the past few decades, dramatic advances in the surgical and medical care of these patients have led to marked improvements in patient outcomes. However, none of the treatments currently in clinical use address the underlying molecular causes of these disorders. Fortunately, the field of craniofacial developmental biology provides a strong foundation for improved diagnosis and for therapies that target the genetic causes of birth defects. In this chapter, we discuss recent advances in our understanding of the embryology of craniofacial conditions, and we focus on the use of animal models to guide rational therapies anchored in genetics and biochemistry.
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Affiliation(s)
- Alice F Goodwin
- Program in Craniofacial Biology, University of California San Francisco, San Francisco, California, USA; Department of Orofacial Sciences, University of California San Francisco, San Francisco, California, USA
| | - Rebecca Kim
- Program in Craniofacial Biology, University of California San Francisco, San Francisco, California, USA; Department of Orofacial Sciences, University of California San Francisco, San Francisco, California, USA
| | - Jeffrey O Bush
- Program in Craniofacial Biology, University of California San Francisco, San Francisco, California, USA; Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, USA; Institute for Human Genetics, University of California San Francisco, San Francisco, California, USA.
| | - Ophir D Klein
- Program in Craniofacial Biology, University of California San Francisco, San Francisco, California, USA; Department of Orofacial Sciences, University of California San Francisco, San Francisco, California, USA; Department of Pediatrics, University of California San Francisco, San Francisco, California, USA; Institute for Human Genetics, University of California San Francisco, San Francisco, California, USA.
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57
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SHP2 sails from physiology to pathology. Eur J Med Genet 2015; 58:509-25. [PMID: 26341048 DOI: 10.1016/j.ejmg.2015.08.005] [Citation(s) in RCA: 165] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 07/24/2015] [Accepted: 08/30/2015] [Indexed: 02/08/2023]
Abstract
Over the two past decades, mutations of the PTPN11 gene, encoding the ubiquitous protein tyrosine phosphatase SHP2 (SH2 domain-containing tyrosine phosphatase 2), have been identified as the causal factor of several developmental diseases (Noonan syndrome (NS), Noonan syndrome with multiple lentigines (NS-ML), and metachondromatosis), and malignancies (juvenile myelomonocytic leukemia). SHP2 plays essential physiological functions in organism development and homeostasis maintenance by regulating fundamental intracellular signaling pathways in response to a wide range of growth factors and hormones, notably the pleiotropic Ras/Mitogen-Activated Protein Kinase (MAPK) and the Phosphoinositide-3 Kinase (PI3K)/AKT cascades. Analysis of the biochemical impacts of PTPN11 mutations first identified both loss-of-function and gain-of-function mutations, as well as more subtle defects, highlighting the major pathophysiological consequences of SHP2 dysregulation. Then, functional genetic studies provided insights into the molecular dysregulations that link SHP2 mutants to the development of specific traits of the diseases, paving the way for the design of specific therapies for affected patients. In this review, we first provide an overview of SHP2's structure and regulation, then describe its molecular roles, notably its functions in modulating the Ras/MAPK and PI3K/AKT signaling pathways, and its physiological roles in organism development and homeostasis. In the second part, we describe the different PTPN11 mutation-associated pathologies and their clinical manifestations, with particular focus on the biochemical and signaling outcomes of NS and NS-ML-associated mutations, and on the recent advances regarding the pathophysiology of these diseases.
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58
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Gelb BD, Roberts AE, Tartaglia M. Cardiomyopathies in Noonan syndrome and the other RASopathies. PROGRESS IN PEDIATRIC CARDIOLOGY 2015; 39:13-19. [PMID: 26380542 PMCID: PMC4568836 DOI: 10.1016/j.ppedcard.2015.01.002] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Noonan syndrome and related disorders (Noonan syndrome with multiple lentigines, Costello syndrome, cardiofaciocutaneous syndrome, Noonan syndrome with loose anagen hair, and other related traits) are autosomal dominant traits. Mutations causing these disorders alter proteins relevant for signaling through RAS. Thus, these traits are now collectively called the RASopathies. While the RASopathies have pleiomorphic features, this review will focus on the hypertrophic cardiomyopathy observed in varying percentages of all of these traits. In addition, inherited abnormalities in one pathway gene, RAF1, cause pediatric-onset dilated cardiomyopathy. The pathogeneses for the RASopathy-associated cardiomyopathies are being elucidated, principally using animal models, leading to genotype-specific insights into how signal transduction is perturbed. Based on those findings, small molecule therapies seem possible for RASopathy-associated cardiomyopathies.
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Affiliation(s)
- Bruce D Gelb
- Mindich Child Health and Development Institute, Departments of Pediatrics and Genetics & Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Amy E Roberts
- Department of Cardiology and Division of Genetics, Boston Children's Hospital, Boston, MA
| | - Marco Tartaglia
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Rome, Italy
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59
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Hernández-Porras I, Jiménez-Catalán B, Schuhmacher AJ, Guerra C. The impact of the genetic background in the Noonan syndrome phenotype induced by K-Ras(V14I). Rare Dis 2015; 3:e1045169. [PMID: 26458870 PMCID: PMC4590006 DOI: 10.1080/21675511.2015.1045169] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 04/02/2015] [Accepted: 04/21/2015] [Indexed: 12/12/2022] Open
Abstract
Noonan syndrome (NS) is an autosomal dominant genetic disorder characterized by short stature, craniofacial dysmorphism, and congenital heart defects. A significant fraction of NS-patients also develop myeloproliferative disorders. The penetrance of these defects varies considerably among patients. In this study, we have examined the effect of 2 genetic backgrounds (C57BL/6J.OlaHsd and 129S2/SvPasCrl) on the phenotypes displayed by a mouse model of NS induced by germline expression of the mutated K-RasV14I allele, one of the most frequent NS-KRAS mutations. Our results suggest the presence of genetic modifiers associated to the genetic background that are essential for heart development and function at early stages of postnatal life as well as in the severity of the haematopoietic alterations.
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Affiliation(s)
| | | | - Alberto J Schuhmacher
- Molecular Oncology; Centro Nacional de Investigaciones Oncológicas (CNIO) ; Madrid, Spain
| | - Carmen Guerra
- Molecular Oncology; Centro Nacional de Investigaciones Oncológicas (CNIO) ; Madrid, Spain
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60
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Abstract
Noonan syndrome (NS) is an autosomal dominant genetic disorder characterized by short stature, craniofacial dysmorphism, and congenital heart defects. NS also is associated with a risk for developing myeloproliferative disorders (MPD), including juvenile myelomonocytic leukemia (JMML). Mutations responsible for NS occur in at least 11 different loci including KRAS. Here we describe a mouse model for NS induced by K-Ras(V14I), a recurrent KRAS mutation in NS patients. K-Ras(V14I)-mutant mice displayed multiple NS-associated developmental defects such as growth delay, craniofacial dysmorphia, cardiac defects, and hematologic abnormalities including a severe form of MPD that resembles human JMML. Homozygous animals had perinatal lethality whose penetrance varied with genetic background. Exposure of pregnant mothers to a MEK inhibitor rescued perinatal lethality and prevented craniofacial dysmorphia and cardiac defects. However, Mek inhibition was not sufficient to correct these defects when mice were treated after weaning. Interestingly, Mek inhibition did not correct the neoplastic MPD characteristic of these mutant mice, regardless of the timing at which the mice were treated, thus suggesting that MPD is driven by additional signaling pathways. These genetically engineered K-Ras(V14I)-mutant mice offer an experimental tool for studying the molecular mechanisms underlying the clinical manifestations of NS. Perhaps more importantly, they should be useful as a preclinical model to test new therapies aimed at preventing or ameliorating those deficits associated with this syndrome.
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61
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Flex E, Jaiswal M, Pantaleoni F, Martinelli S, Strullu M, Fansa EK, Caye A, De Luca A, Lepri F, Dvorsky R, Pannone L, Paolacci S, Zhang SC, Fodale V, Bocchinfuso G, Rossi C, Burkitt-Wright EMM, Farrotti A, Stellacci E, Cecchetti S, Ferese R, Bottero L, Castro S, Fenneteau O, Brethon B, Sanchez M, Roberts AE, Yntema HG, Van Der Burgt I, Cianci P, Bondeson ML, Cristina Digilio M, Zampino G, Kerr B, Aoki Y, Loh ML, Palleschi A, Di Schiavi E, Carè A, Selicorni A, Dallapiccola B, Cirstea IC, Stella L, Zenker M, Gelb BD, Cavé H, Ahmadian MR, Tartaglia M. Activating mutations in RRAS underlie a phenotype within the RASopathy spectrum and contribute to leukaemogenesis. Hum Mol Genet 2014; 23:4315-27. [PMID: 24705357 PMCID: PMC4103678 DOI: 10.1093/hmg/ddu148] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 03/04/2014] [Indexed: 12/29/2022] Open
Abstract
RASopathies, a family of disorders characterized by cardiac defects, defective growth, facial dysmorphism, variable cognitive deficits and predisposition to certain malignancies, are caused by constitutional dysregulation of RAS signalling predominantly through the RAF/MEK/ERK (MAPK) cascade. We report on two germline mutations (p.Gly39dup and p.Val55Met) in RRAS, a gene encoding a small monomeric GTPase controlling cell adhesion, spreading and migration, underlying a rare (2 subjects among 504 individuals analysed) and variable phenotype with features partially overlapping Noonan syndrome, the most common RASopathy. We also identified somatic RRAS mutations (p.Gly39dup and p.Gln87Leu) in 2 of 110 cases of non-syndromic juvenile myelomonocytic leukaemia, a childhood myeloproliferative/myelodysplastic disease caused by upregulated RAS signalling, defining an atypical form of this haematological disorder rapidly progressing to acute myeloid leukaemia. Two of the three identified mutations affected known oncogenic hotspots of RAS genes and conferred variably enhanced RRAS function and stimulus-dependent MAPK activation. Expression of an RRAS mutant homolog in Caenorhabditis elegans enhanced RAS signalling and engendered protruding vulva, a phenotype previously linked to the RASopathy-causing SHOC2(S2G) mutant. Overall, these findings provide evidence of a functional link between RRAS and MAPK signalling and reveal an unpredicted role of enhanced RRAS function in human disease.
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Affiliation(s)
- Elisabetta Flex
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare and
| | - Mamta Jaiswal
- Institut für Biochemie und Molekularbiologie II, Medizinische Fakultät der Heinrich-Heine Universitat, Düsseldorf 40225, Germany
| | | | | | - Marion Strullu
- Genetics Department, INSERM UMR_S940, Institut Universitaire D'Hématologie (IUH), Université Paris-Diderot Sorbonne-Paris-Cité, Paris 75010, France
| | - Eyad K Fansa
- Institut für Biochemie und Molekularbiologie II, Medizinische Fakultät der Heinrich-Heine Universitat, Düsseldorf 40225, Germany
| | - Aurélie Caye
- Genetics Department, INSERM UMR_S940, Institut Universitaire D'Hématologie (IUH), Université Paris-Diderot Sorbonne-Paris-Cité, Paris 75010, France
| | - Alessandro De Luca
- Laboratorio Mendel, Istituto di Ricovero e Cura a Carattere Scientifico-Casa Sollievo Della Sofferenza, Rome 00198, Italy
| | | | - Radovan Dvorsky
- Institut für Biochemie und Molekularbiologie II, Medizinische Fakultät der Heinrich-Heine Universitat, Düsseldorf 40225, Germany
| | - Luca Pannone
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare and
| | | | - Si-Cai Zhang
- Institut für Biochemie und Molekularbiologie II, Medizinische Fakultät der Heinrich-Heine Universitat, Düsseldorf 40225, Germany
| | | | - Gianfranco Bocchinfuso
- Dipartimento di Scienze e Tecnologie Chimiche, Università 'Tor Vergata', Rome 00133, Italy
| | - Cesare Rossi
- UO Genetica Medica, Policlinico S.Orsola-Malpighi, Bologna 40138, Italy
| | - Emma M M Burkitt-Wright
- Genetic Medicine, Academic Health Science Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester M13 9WL, UK
| | - Andrea Farrotti
- Dipartimento di Scienze e Tecnologie Chimiche, Università 'Tor Vergata', Rome 00133, Italy
| | | | - Serena Cecchetti
- Dipartimento di Biologia Cellulare e Neuroscienze, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Rosangela Ferese
- Laboratorio Mendel, Istituto di Ricovero e Cura a Carattere Scientifico-Casa Sollievo Della Sofferenza, Rome 00198, Italy
| | | | - Silvana Castro
- Istituto di Genetica e Biofisica 'A. Buzzati Traverso', Consiglio Nazionale Delle Ricerche, Naples 80131, Italy
| | | | - Benoît Brethon
- Pediatric Hematology Department, Robert Debré Hospital, Paris 75019, France
| | - Massimo Sanchez
- Dipartimento di Biologia Cellulare e Neuroscienze, Istituto Superiore di Sanità, Rome 00161, Italy
| | - Amy E Roberts
- Department of Cardiology and Division of Genetics, and Department of Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Helger G Yntema
- Department of Human Genetics, Radboud University Medical Centre, and Nijmegen Centre for Molecular Life Sciences, Radboud University, Nijmegen 6500, The Netherlands
| | - Ineke Van Der Burgt
- Department of Human Genetics, Radboud University Medical Centre, and Nijmegen Centre for Molecular Life Sciences, Radboud University, Nijmegen 6500, The Netherlands
| | - Paola Cianci
- Genetica Clinica Pediatrica, Clinica Pediatrica Università Milano Bicocca, Fondazione MBBM, A.O. S. Gerardo, Monza 20900, Italy
| | - Marie-Louise Bondeson
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala 75237, Sweden
| | | | - Giuseppe Zampino
- Istituto di Clinica Pediatrica, Università Cattolica del Sacro Cuore, Rome 00168, Italy
| | - Bronwyn Kerr
- Genetic Medicine, Academic Health Science Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester M13 9WL, UK
| | - Yoko Aoki
- Department of Medical Genetics, Tohoku University School of Medicine, Sendai 980-8574, Japan
| | - Mignon L Loh
- Department of Pediatrics, Benioff Children's Hospital, University of California School of Medicine, and the Helen Diller Family Comprehensive Cancer Center, San Francisco, CA, 94143, USA
| | - Antonio Palleschi
- Dipartimento di Scienze e Tecnologie Chimiche, Università 'Tor Vergata', Rome 00133, Italy
| | - Elia Di Schiavi
- Istituto di Genetica e Biofisica 'A. Buzzati Traverso', Consiglio Nazionale Delle Ricerche, Naples 80131, Italy
| | - Alessandra Carè
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare and
| | - Angelo Selicorni
- Genetica Clinica Pediatrica, Clinica Pediatrica Università Milano Bicocca, Fondazione MBBM, A.O. S. Gerardo, Monza 20900, Italy
| | | | - Ion C Cirstea
- Institut für Biochemie und Molekularbiologie II, Medizinische Fakultät der Heinrich-Heine Universitat, Düsseldorf 40225, Germany, Leibniz Institute for Age Research, Jena 07745, Germany
| | - Lorenzo Stella
- Dipartimento di Scienze e Tecnologie Chimiche, Università 'Tor Vergata', Rome 00133, Italy
| | - Martin Zenker
- Institute of Human Genetics, University Hospital of Magdeburg, Otto-von-Guericke-University, Magdeburg 39120, Germany
| | - Bruce D Gelb
- Department of Pediatrics and Department of Genetics and Department of Genomic Sciences, Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Hélène Cavé
- Genetics Department, INSERM UMR_S940, Institut Universitaire D'Hématologie (IUH), Université Paris-Diderot Sorbonne-Paris-Cité, Paris 75010, France
| | - Mohammad R Ahmadian
- Institut für Biochemie und Molekularbiologie II, Medizinische Fakultät der Heinrich-Heine Universitat, Düsseldorf 40225, Germany
| | - Marco Tartaglia
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare and
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Next-generation sequencing identifies rare variants associated with Noonan syndrome. Proc Natl Acad Sci U S A 2014; 111:11473-8. [PMID: 25049390 DOI: 10.1073/pnas.1324128111] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Noonan syndrome (NS) is a relatively common genetic disorder, characterized by typical facies, short stature, developmental delay, and cardiac abnormalities. Known causative genes account for 70-80% of clinically diagnosed NS patients, but the genetic basis for the remaining 20-30% of cases is unknown. We performed next-generation sequencing on germ-line DNA from 27 NS patients lacking a mutation in the known NS genes. We identified gain-of-function alleles in Ras-like without CAAX 1 (RIT1) and mitogen-activated protein kinase kinase 1 (MAP2K1) and previously unseen loss-of-function variants in RAS p21 protein activator 2 (RASA2) that are likely to cause NS in these patients. Expression of the mutant RASA2, MAP2K1, or RIT1 alleles in heterologous cells increased RAS-ERK pathway activation, supporting a causative role in NS pathogenesis. Two patients had more than one disease-associated variant. Moreover, the diagnosis of an individual initially thought to have NS was revised to neurofibromatosis type 1 based on an NF1 nonsense mutation detected in this patient. Another patient harbored a missense mutation in NF1 that resulted in decreased protein stability and impaired ability to suppress RAS-ERK activation; however, this patient continues to exhibit a NS-like phenotype. In addition, a nonsense mutation in RPS6KA3 was found in one patient initially diagnosed with NS whose diagnosis was later revised to Coffin-Lowry syndrome. Finally, we identified other potential candidates for new NS genes, as well as potential carrier alleles for unrelated syndromes. Taken together, our data suggest that next-generation sequencing can provide a useful adjunct to RASopathy diagnosis and emphasize that the standard clinical categories for RASopathies might not be adequate to describe all patients.
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Inoue SI, Moriya M, Watanabe Y, Miyagawa-Tomita S, Niihori T, Oba D, Ono M, Kure S, Ogura T, Matsubara Y, Aoki Y. New BRAF knockin mice provide a pathogenetic mechanism of developmental defects and a therapeutic approach in cardio-facio-cutaneous syndrome. Hum Mol Genet 2014; 23:6553-66. [PMID: 25035421 DOI: 10.1093/hmg/ddu376] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Cardio-facio-cutaneous (CFC) syndrome is one of the 'RASopathies', a group of phenotypically overlapping syndromes caused by germline mutations that encode components of the RAS-MAPK pathway. Germline mutations in BRAF cause CFC syndrome, which is characterized by heart defects, distinctive facial features and ectodermal abnormalities. To define the pathogenesis and to develop a potential therapeutic approach in CFC syndrome, we here generated new knockin mice (here Braf(Q241R/+)) expressing the Braf Q241R mutation, which corresponds to the most frequent mutation in CFC syndrome, Q257R. Braf(Q241R/+) mice manifested embryonic/neonatal lethality, showing liver necrosis, edema and craniofacial abnormalities. Histological analysis revealed multiple heart defects, including cardiomegaly, enlarged cardiac valves, ventricular noncompaction and ventricular septal defects. Braf(Q241R/+) embryos also showed massively distended jugular lymphatic sacs and subcutaneous lymphatic vessels, demonstrating lymphatic defects in RASopathy knockin mice for the first time. Prenatal treatment with a MEK inhibitor, PD0325901, rescued the embryonic lethality with amelioration of craniofacial abnormalities and edema in Braf(Q241R/+) embryos. Unexpectedly, one surviving pup was obtained after treatment with a histone 3 demethylase inhibitor, GSK-J4, or NCDM-32b. Combination treatment with PD0325901 and GSK-J4 further increased the rescue from embryonic lethality, ameliorating enlarged cardiac valves. These results suggest that our new Braf knockin mice recapitulate major features of RASopathies and that epigenetic modulation as well as the inhibition of the ERK pathway will be a potential therapeutic strategy for the treatment of CFC syndrome.
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Affiliation(s)
| | | | - Yusuke Watanabe
- Department of Developmental Neurobiology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | - Sachiko Miyagawa-Tomita
- Department of Pediatric Cardiology, Division of Cardiovascular Development and Differentiation, Medical Research Institute, Tokyo Women's Medical University, Tokyo, Japan and
| | | | | | | | - Shigeo Kure
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan
| | - Toshihiko Ogura
- Department of Developmental Neurobiology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | - Yoichi Matsubara
- Department of Medical Genetics, National Research Institute for Child Health and Development, Tokyo, Japan
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Approach for targeting Ras with small molecules that activate SOS-mediated nucleotide exchange. Proc Natl Acad Sci U S A 2014; 111:3401-6. [PMID: 24550516 DOI: 10.1073/pnas.1315798111] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Aberrant activation of the small GTPase Ras by oncogenic mutation or constitutively active upstream receptor tyrosine kinases results in the deregulation of cellular signals governing growth and survival in ∼30% of all human cancers. However, the discovery of potent inhibitors of Ras has been difficult to achieve. Here, we report the identification of small molecules that bind to a unique pocket on the Ras:Son of Sevenless (SOS):Ras complex, increase the rate of SOS-catalyzed nucleotide exchange in vitro, and modulate Ras signaling pathways in cells. X-ray crystallography of Ras:SOS:Ras in complex with these molecules reveals that the compounds bind in a hydrophobic pocket in the CDC25 domain of SOS adjacent to the Switch II region of Ras. The structure-activity relationships exhibited by these compounds can be rationalized on the basis of multiple X-ray cocrystal structures. Mutational analyses confirmed the functional relevance of this binding site and showed it to be essential for compound activity. These molecules increase Ras-GTP levels and disrupt MAPK and PI3K signaling in cells at low micromolar concentrations. These small molecules represent tools to study the acute activation of Ras and highlight a pocket on SOS that may be exploited to modulate Ras signaling.
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The paradox of FGFR3 signaling in skeletal dysplasia: Why chondrocytes growth arrest while other cells over proliferate. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2014; 759:40-8. [DOI: 10.1016/j.mrrev.2013.11.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 11/03/2013] [Accepted: 11/20/2013] [Indexed: 11/19/2022]
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Tumurkhuu M, Saitoh M, Takita J, Mizuno Y, Mizuguchi M. A novel SOS1 mutation in Costello/CFC syndrome affects signaling in both RAS and PI3K pathways. J Recept Signal Transduct Res 2013; 33:124-8. [PMID: 23528009 DOI: 10.3109/10799893.2013.779279] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
CONTEXT Pathological upregulation of the RAS/MAPK pathway causes Costello, Noonan and cardio-facio-cutaneous (CFC) syndrome; however, little is known about PI3K/AKT signal transduction in these syndromes. Previously, we found a novel mutation of the SOS1 gene (T158A) in a patient with Costello/CFC overlapping phenotype. OBJECTIVE The aim of this study was to investigate how this mutation affects RAS/MAPK as well as PI3K/AKT pathway signal transduction. MATERIALS AND METHODS Wild-type and mutant (T158A) Son of Sevenless 1 (SOS1) were transfected into 293T cells. The levels of phospho- and total ERK1/2, AKT, p70S6K and pS6 were examined under epidermal growth factor (EGF) stimulation. RESULTS After EGF stimulation, the ratio of phospho-ERK1/2 to total ERK1/2 was highest at 5 min in mutant (T158A) SOS1 cells, and at 15 min in wild-type SOS1 cells. Phospho-AKT was less abundant at 60 min in mutant than in wild-type SOS1 cells. Phosphorylation at various sites in p70S6K differed between wild-type and mutant cells. Eighteen hours after activation by EGF, the ratio of phospho-ERK1/2 to total ERK1/2 remained significantly higher in mutant than in wild-type SOS1 cells, but that of phospho-AKT to total AKT was unchanged. DISCUSSION T158A is located in the histone-like domain, which may have a role in auto-inhibition of RAS exchanger activity of SOS1. T158A may disrupt auto-inhibition and enhance RAS signaling. T158A also affects PI3K/AKT signaling, probably via negative feedback via phospho-p70S6K. CONCLUSION The SOS1 T158A mutation altered the phosphorylation of gene products involved in both RAS/MAPK and PI3K/AKT pathways.
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Affiliation(s)
- Munkhtuya Tumurkhuu
- Department of Developmental Medical Sciences, Institute of International Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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Goodwin AF, Tidyman WE, Jheon AH, Sharir A, Zheng X, Charles C, Fagin JA, McMahon M, Diekwisch TGH, Ganss B, Rauen KA, Klein OD. Abnormal Ras signaling in Costello syndrome (CS) negatively regulates enamel formation. Hum Mol Genet 2013; 23:682-92. [PMID: 24057668 DOI: 10.1093/hmg/ddt455] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
RASopathies are syndromes caused by gain-of-function mutations in the Ras signaling pathway. One of these conditions, Costello syndrome (CS), is typically caused by an activating de novo germline mutation in HRAS and is characterized by a wide range of cardiac, musculoskeletal, dermatological and developmental abnormalities. We report that a majority of individuals with CS have hypo-mineralization of enamel, the outer covering of teeth, and that similar defects are present in a CS mouse model. Comprehensive analysis of the mouse model revealed that ameloblasts, the cells that generate enamel, lacked polarity, and the ameloblast progenitor cells were hyperproliferative. Ras signals through two main effector cascades, the mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3-kinase (PI3K) pathways. To determine through which pathway Ras affects enamel formation, inhibitors targeting either PI3K or MEK 1 and 2 (MEK 1/2), kinases in the MAPK pathway, were utilized. MEK1/2 inhibition rescued the hypo-mineralized enamel, normalized the ameloblast polarity defect and restored normal progenitor cell proliferation. In contrast, PI3K inhibition only corrected the progenitor cell proliferation phenotype. We demonstrate for the first time the central role of Ras signaling in enamel formation in CS individuals and present the mouse incisor as a model system to dissect the roles of the Ras effector pathways in vivo.
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Affiliation(s)
- Alice F Goodwin
- Department of Orofacial Sciences and Program in Craniofacial and Mesenchymal Biology
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Jun JE, Rubio I, Roose JP. Regulation of ras exchange factors and cellular localization of ras activation by lipid messengers in T cells. Front Immunol 2013; 4:239. [PMID: 24027568 PMCID: PMC3762125 DOI: 10.3389/fimmu.2013.00239] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Accepted: 08/02/2013] [Indexed: 11/17/2022] Open
Abstract
The Ras-MAPK signaling pathway is highly conserved throughout evolution and is activated downstream of a wide range of receptor stimuli. Ras guanine nucleotide exchange factors (RasGEFs) catalyze GTP loading of Ras and play a pivotal role in regulating receptor-ligand induced Ras activity. In T cells, three families of functionally important RasGEFs are expressed: RasGRF, RasGRP, and Son of Sevenless (SOS)-family GEFs. Early on it was recognized that Ras activation is critical for T cell development and that the RasGEFs play an important role herein. More recent work has revealed that nuances in Ras activation appear to significantly impact T cell development and selection. These nuances include distinct biochemical patterns of analog versus digital Ras activation, differences in cellular localization of Ras activation, and intricate interplays between the RasGEFs during distinct T cell developmental stages as revealed by various new mouse models. In many instances, the exact nature of these nuances in Ras activation or how these may result from fine-tuning of the RasGEFs is not understood. One large group of biomolecules critically involved in the control of RasGEFs functions are lipid second messengers. Multiple, yet distinct lipid products are generated following T cell receptor (TCR) stimulation and bind to different domains in the RasGRP and SOS RasGEFs to facilitate the activation of the membrane-anchored Ras GTPases. In this review we highlight how different lipid-based elements are generated by various enzymes downstream of the TCR and other receptors and how these dynamic and interrelated lipid products may fine-tune Ras activation by RasGEFs in developing T cells.
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Affiliation(s)
- Jesse E Jun
- Department of Anatomy, University of California San Francisco , San Francisco, CA , USA
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Abstract
The RASopathies are a clinically defined group of medical genetic syndromes caused by germline mutations in genes that encode components or regulators of the Ras/mitogen-activated protein kinase (MAPK) pathway. These disorders include neurofibromatosis type 1, Noonan syndrome, Noonan syndrome with multiple lentigines, capillary malformation-arteriovenous malformation syndrome, Costello syndrome, cardio-facio-cutaneous syndrome, and Legius syndrome. Because of the common underlying Ras/MAPK pathway dysregulation, the RASopathies exhibit numerous overlapping phenotypic features. The Ras/MAPK pathway plays an essential role in regulating the cell cycle and cellular growth, differentiation, and senescence, all of which are critical to normal development. Therefore, it is not surprising that Ras/MAPK pathway dysregulation has profound deleterious effects on both embryonic and later stages of development. The Ras/MAPK pathway has been well studied in cancer and is an attractive target for small-molecule inhibition to treat various malignancies. The use of these molecules to ameliorate developmental defects in the RASopathies is under consideration.
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Affiliation(s)
- Katherine A Rauen
- Department of Pediatrics, Division of Medical Genetics, and Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, California 94115;
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Aoki Y, Matsubara Y. Ras/MAPK syndromes and childhood hemato-oncological diseases. Int J Hematol 2012; 97:30-6. [PMID: 23250860 DOI: 10.1007/s12185-012-1239-y] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Revised: 12/03/2012] [Accepted: 12/04/2012] [Indexed: 11/25/2022]
Abstract
Noonan syndrome (NS) is an autosomal-dominant disease characterized by distinctive facial features, webbed neck, cardiac anomalies, short stature and cryptorchidism. NS exhibits phenotypic overlap with Costello syndrome and cardio-facio-cutaneous (CFC) syndrome. Germline mutations of genes encoding proteins in the RAS/mitogen-activated protein kinase (MAPK) pathway cause NS and related disorders. Germline mutations in PTPN11, KRAS, SOS1, RAF1, and NRAS have been identified in 60-80 % of NS patients. Germline mutations in HRAS have been identified in patients with Costello syndrome and mutations in KRAS, BRAF, and MAP2K1/2 (MEK1/2) have been identified in patients with CFC syndrome. Recently, mutations in SHOC2 and CBL have been identified in patients with Noonan-like syndrome. It has been suggested that these syndromes be comprehensively termed RAS/MAPK syndromes, or RASopathies. Molecular analysis is beneficial for the confirmation of clinical diagnoses and follow-up with patients using a tumor-screening protocol, as patients with NS and related disorders have an increased risk of developing tumors. In this review, we summarize the genetic mutations, clinical manifestations, associations with malignant tumors, and possible therapeutic approaches for these disorders.
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Affiliation(s)
- Yoko Aoki
- Department of Medical Genetics, Tohoku University School of Medicine, 1-1 Seiryo-machi, Sendai, Japan.
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Lauriol J, Kontaridis MI. PTPN11-associated mutations in the heart: has LEOPARD changed Its RASpots? Trends Cardiovasc Med 2012; 21:97-104. [PMID: 22681964 DOI: 10.1016/j.tcm.2012.03.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In this review, we focus on elucidating the cardiac function of germline mutations in the PTPN11 gene, encoding the Src homology-2 (SH2) domain-containing protein tyrosine phosphatase SHP2. PTPN11 mutations cause LEOPARD syndrome (LS) and Noonan syndrome (NS), two disorders that are part of a newly classified family of autosomal dominant syndromes termed "RASopathies," which are caused by germline mutations in components of the RAS/RAF/MEK/ERK mitogen activating protein kinase pathway. LS and NS mutants have opposing biochemical properties, and yet, in patients, these mutations produce similar cardiac abnormalities. Precisely how LS and NS mutations lead to such similar disease etiology remains largely unknown. Recent complementary in vitro, ex vivo, and in vivo analyses reveal new insights into the functions of SHP2 in normal and pathological cardiac development. These findings also reveal the need for individualized therapeutic approaches in the treatment of patients with LS and NS and, more broadly, patients with the other "RASopathy" gene mutations as well.
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Affiliation(s)
- Jessica Lauriol
- Department of Medicine, Division of Cardiology, Beth Israel Deaconess Medical Center, Boston, MA 02115, USA
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Saha M, Carriere A, Cheerathodi M, Zhang X, Lavoie G, Rush J, Roux PP, Ballif BA. RSK phosphorylates SOS1 creating 14-3-3-docking sites and negatively regulating MAPK activation. Biochem J 2012; 447:159-66. [PMID: 22827337 PMCID: PMC4198020 DOI: 10.1042/bj20120938] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The extent and duration of MAPK (mitogen-activated protein kinase) signalling govern a diversity of normal and aberrant cellular outcomes. Genetic and pharmacological disruption of the MAPK-activated kinase RSK (ribosomal S6 kinase) leads to elevated MAPK activity indicative of a RSK-dependent negative feedback loop. Using biochemical, pharmacological and quantitative MS approaches we show that RSK phosphorylates the Ras activator SOS1 (Son of Sevenless homologue 1) in cultured cells on two C-terminal residues, Ser(1134) and Ser(1161). Furthermore, we find that RSK-dependent SOS1 phosphorylation creates 14-3-3-binding sites. We show that mutating Ser(1134) and Ser(1161) disrupts 14-3-3 binding and modestly increases and extends MAPK activation. Together these data suggest that one mechanism whereby RSK negatively regulates MAPK activation is via site-specific SOS1 phosphorylation.
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Affiliation(s)
- Madhurima Saha
- Department of Biology, University of Vermont, Burlington, VT, 05405, U.S.A
| | - Audrey Carriere
- Institute for Research in Immunology and Cancer (IRIC), Montréal, Québec, Canada H3C 3J7
- Department of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada H3C 3J7
| | | | - Xiaocui Zhang
- Institute for Research in Immunology and Cancer (IRIC), Montréal, Québec, Canada H3C 3J7
| | - Geneviève Lavoie
- Institute for Research in Immunology and Cancer (IRIC), Montréal, Québec, Canada H3C 3J7
| | - John Rush
- Cell Signaling Technology, Inc., 3 Trask Lane, Danvers, MA, 01923, U.S.A
| | - Philippe P. Roux
- Institute for Research in Immunology and Cancer (IRIC), Montréal, Québec, Canada H3C 3J7
- Department of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada H3C 3J7
| | - Bryan A. Ballif
- Department of Biology, University of Vermont, Burlington, VT, 05405, U.S.A
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Sala V, Gallo S, Leo C, Gatti S, Gelb BD, Crepaldi T. Signaling to cardiac hypertrophy: insights from human and mouse RASopathies. Mol Med 2012; 18:938-47. [PMID: 22576369 DOI: 10.2119/molmed.2011.00512] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Accepted: 05/04/2012] [Indexed: 12/19/2022] Open
Abstract
Cardiac hypertrophy is the heart's response to a variety of extrinsic and intrinsic stimuli, some of which might finally lead up to a maladaptive state. An integral part of the pathogenesis of the hypertrophic cardiomyopathy disease (HCM) is the activation of the rat sarcoma (RAS)/RAF/MEK (mitogen-activated protein kinase kinase)/MAPK (mitogen-activated protein kinase) cascade. Therefore, the molecular signaling involving RAS has been the subject of intense research efforts, particularly after the identification of the RASopathies. These constitute a class of developmental disorders caused by germline mutations affecting proteins contributing to the RAS pathway. Among other phenotypic features, a subset of these syndromes is characterized by HCM, prompting researchers and clinicians to delve into the chief signaling constituents of cardiac hypertrophy. In this review, we summarize current advances in the knowledge of the molecular signaling events involved in the pathogenesis of cardiac hypertrophy through work completed on patients and on genetically manipulated animals with HCM and RASopathies. Important insights are drawn from the recognition of parallels between cardiac hypertrophy and cancer. Future research promises to further elucidate the complex molecular interactions responsible for cardiac hypertrophy, possibly pointing the way for the identification of new specific targets for the treatment of HCM.
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Affiliation(s)
- Valentina Sala
- Department of Anatomy, Pharmacology and Forensic Medicine, University of Turin, Turin, Italy
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Bhattacharya A, Klann E. The molecular basis of cognitive deficits in pervasive developmental disorders. Learn Mem 2012; 19:434-43. [PMID: 22904374 DOI: 10.1101/lm.025007.111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Persons with pervasive developmental disorders (PDD) exhibit a range of cognitive deficits that hamper their quality of life, including difficulties involving communication, sociability, and perspective-taking. In recent years, a variety of studies in mice that model genetic syndromes with a high risk of PDD have provided insights into the underlying molecular mechanisms associated with these disorders. What is less appreciated is how the molecular anomalies affect neuronal and circuit function to give rise to the cognitive deficits associated with PDD. In this review, we describe genetic mutations that cause PDD and discuss how they alter fundamental social and cognitive processes. We then describe efforts to correct cognitive impairments associated with these disorders and identify areas of further inquiry in the search for molecular targets for therapeutics for PDD.
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Affiliation(s)
- Aditi Bhattacharya
- Center for Neural Science, New York University, New York, New York 10003, USA
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75
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Increased BRAF heterodimerization is the common pathogenic mechanism for noonan syndrome-associated RAF1 mutants. Mol Cell Biol 2012; 32:3872-90. [PMID: 22826437 DOI: 10.1128/mcb.00751-12] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Noonan syndrome (NS) is a relatively common autosomal dominant disorder characterized by congenital heart defects, short stature, and facial dysmorphia. NS is caused by germ line mutations in several components of the RAS-RAF-MEK-extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) pathway, including both kinase-activating and kinase-impaired alleles of RAF1 (∼3 to 5%), which encodes a serine-threonine kinase for MEK1/2. To investigate how kinase-impaired RAF1 mutants cause NS, we generated knock-in mice expressing Raf1(D486N). Raf1(D486N/+) (here D486N/+) female mice exhibited a mild growth defect. Male and female D486N/D486N mice developed concentric cardiac hypertrophy and incompletely penetrant, but severe, growth defects. Remarkably, Mek/Erk activation was enhanced in Raf1(D486N)-expressing cells compared with controls. RAF1(D486N), as well as other kinase-impaired RAF1 mutants, showed increased heterodimerization with BRAF, which was necessary and sufficient to promote increased MEK/ERK activation. Furthermore, kinase-activating RAF1 mutants also required heterodimerization to enhance MEK/ERK activation. Our results suggest that an increased heterodimerization ability is the common pathogenic mechanism for NS-associated RAF1 mutations.
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Noonan syndrome-causing SHP2 mutants inhibit insulin-like growth factor 1 release via growth hormone-induced ERK hyperactivation, which contributes to short stature. Proc Natl Acad Sci U S A 2012; 109:4257-62. [PMID: 22371576 DOI: 10.1073/pnas.1119803109] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Noonan syndrome (NS), a genetic disease caused in half of cases by activating mutations of the tyrosine phosphatase SHP2 (PTPN11), is characterized by congenital cardiopathies, facial dysmorphic features, and short stature. How mutated SHP2 induces growth retardation remains poorly understood. We report here that early postnatal growth delay is associated with low levels of insulin-like growth factor 1 (IGF-1) in a mouse model of NS expressing the D61G mutant of SHP2. Conversely, inhibition of SHP2 expression in growth hormone (GH)-responsive cell lines results in increased IGF-1 release upon GH stimulation. SHP2-deficient cells display decreased ERK1/2 phosphorylation and rat sarcoma (RAS) activation in response to GH, whereas expression of NS-associated SHP2 mutants results in ERK1/2 hyperactivation in vitro and in vivo. RAS/ERK1/2 inhibition in SHP2-deficient cells correlates with impaired dephosphorylation of the adaptor Grb2-associated binder-1 (GAB1) on its RAS GTPase-activating protein (RASGAP) binding sites and is rescued by interfering with RASGAP recruitment or function. We demonstrate that inhibition of ERK1/2 activation results in an increase of IGF-1 levels in vitro and in vivo, which is associated with significant growth improvement in NS mice. In conclusion, NS-causing SHP2 mutants inhibit GH-induced IGF-1 release through RAS/ERK1/2 hyperactivation, a mechanism that could contribute to growth retardation. This finding suggests that, in addition to its previously shown beneficial effect on NS-linked cardiac and craniofacial defects, RAS/ERK1/2 modulation could also alleviate the short stature phenotype in NS caused by PTPN11 mutations.
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Paternal age effect mutations and selfish spermatogonial selection: causes and consequences for human disease. Am J Hum Genet 2012; 90:175-200. [PMID: 22325359 DOI: 10.1016/j.ajhg.2011.12.017] [Citation(s) in RCA: 227] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 12/05/2011] [Accepted: 12/26/2011] [Indexed: 12/25/2022] Open
Abstract
Advanced paternal age has been associated with an increased risk for spontaneous congenital disorders and common complex diseases (such as some cancers, schizophrenia, and autism), but the mechanisms that mediate this effect have been poorly understood. A small group of disorders, including Apert syndrome (caused by FGFR2 mutations), achondroplasia, and thanatophoric dysplasia (FGFR3), and Costello syndrome (HRAS), which we collectively term "paternal age effect" (PAE) disorders, provides a good model to study the biological and molecular basis of this phenomenon. Recent evidence from direct quantification of PAE mutations in sperm and testes suggests that the common factor in the paternal age effect lies in the dysregulation of spermatogonial cell behavior, an effect mediated molecularly through the growth factor receptor-RAS signal transduction pathway. The data show that PAE mutations, although arising rarely, are positively selected and expand clonally in normal testes through a process akin to oncogenesis. This clonal expansion, which is likely to take place in the testes of all men, leads to the relative enrichment of mutant sperm over time-explaining the observed paternal age effect associated with these disorders-and in rare cases to the formation of testicular tumors. As regulation of RAS and other mediators of cellular proliferation and survival is important in many different biological contexts, for example during tumorigenesis, organ homeostasis and neurogenesis, the consequences of selfish mutations that hijack this process within the testis are likely to extend far beyond congenital skeletal disorders to include complex diseases, such as neurocognitive disorders and cancer predisposition.
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Anastasaki C, Rauen KA, Patton EE. Continual low-level MEK inhibition ameliorates cardio-facio-cutaneous phenotypes in zebrafish. Dis Model Mech 2012; 5:546-52. [PMID: 22301711 PMCID: PMC3380717 DOI: 10.1242/dmm.008672] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cardio-facio-cutaneous (CFC) syndrome is caused by germline mutations in KRAS, BRAF and MEK1/2. The highly selective and potent MEK inhibitors that have been developed as anti-cancer agents hold potential as therapeutics for CFC syndrome. We have previously shown that the effects of CFC mutations on zebrafish gastrulation can be prevented by a 1-hour treatment with MEK inhibitors within a specific developmental time-window. However, MEK activity is essential for normal development and PD0325901 treatment outside this treatment window leads to additional developmental defects in MEK-dependent tissues. We now test ten different doses of PD0325901 at six developmental time points and assess the effects on body axis length, heart development and craniofacial structures in zebrafish embryos. Notably, we find that a continuous low-level dose of PD0325901 that has only minor inhibition of MEK activity can prevent the action of both the common CFC BRAFQ257R kinase-active allele and the BRAFG596V kinase-impaired mutant allele through the first 5 days of development. These results provide a detailed study of the effects of PD0325901 in development and show that, unlike in cancer, which requires robust inhibition of MAPK signalling, a partial reduction in phospho-ERK1/2 activity is sufficient to moderate the developmental effects of BRAFCFC mutations.
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Affiliation(s)
- Corina Anastasaki
- The Institute for Genetics and Molecular Medicine, Medical Research Council, Human Genetics Unit and Edinburgh University, Crewe Road South, Western General Hospital Campus, EH4 2XR, UK
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79
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Rojas JM, Oliva JL, Santos E. Mammalian son of sevenless Guanine nucleotide exchange factors: old concepts and new perspectives. Genes Cancer 2011; 2:298-305. [PMID: 21779500 DOI: 10.1177/1947601911408078] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The Son of Sevenless (Sos) factors were originally discovered 2 decades ago as specialized Ras activators in signaling pathways controlling the process of R7 cell development in the eye of Drosophila melanogaster. The 2 known members of the mammalian Sos family (Sos1 and Sos2) code for ubiquitously expressed, highly homologous (69% overall) proteins involved in coupling signals originated by cell surface receptor tyrosine kinases (RTKs) to downstream, Ras-dependent mitogenic signaling pathways. Mechanistically, the Sos proteins function as enzymatic factors interacting with Ras proteins in response to upstream stimuli to promote guanine nucleotide exchange (GDP/GTP) and subsequent formation of the active Ras-GTP complex. In this review, we summarize current knowledge on structural, regulatory, and functional aspects of the Sos family, focusing on specific aspects of Sos biology such as structure-function relationship, crosstalk with different signaling pathways, and in vivo functional significance as deduced from phenotypic characterization of Sos knockout mice and human genetic syndromes caused by germline hSos1 mutations.
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Affiliation(s)
- José M Rojas
- Unidad de Biología Celular, Área de Biología Celular y del Desarrollo, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain
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80
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Lepri F, De Luca A, Stella L, Rossi C, Baldassarre G, Pantaleoni F, Cordeddu V, Williams BJ, Dentici ML, Caputo V, Venanzi S, Bonaguro M, Kavamura I, Faienza MF, Pilotta A, Stanzial F, Faravelli F, Gabrielli O, Marino B, Neri G, Silengo MC, Ferrero GB, Torrrente I, Selicorni A, Mazzanti L, Digilio MC, Zampino G, Dallapiccola B, Gelb BD, Tartaglia M. SOS1 mutations in Noonan syndrome: molecular spectrum, structural insights on pathogenic effects, and genotype-phenotype correlations. Hum Mutat 2011; 32:760-72. [PMID: 21387466 PMCID: PMC3118925 DOI: 10.1002/humu.21492] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 02/23/2011] [Indexed: 01/03/2023]
Abstract
Noonan syndrome (NS) is among the most common nonchromosomal disorders affecting development and growth. NS is caused by aberrant RAS-MAPK signaling and is genetically heterogeneous, which explains, in part, the marked clinical variability documented for this Mendelian trait. Recently, we and others identified SOS1 as a major gene underlying NS. Here, we explored further the spectrum of SOS1 mutations and their associated phenotypic features. Mutation scanning of the entire SOS1 coding sequence allowed the identification of 33 different variants deemed to be of pathological significance, including 16 novel missense changes and in-frame indels. Various mutation clusters destabilizing or altering orientation of regions of the protein predicted to contribute structurally to the maintenance of autoinhibition were identified. Two previously unappreciated clusters predicted to enhance SOS1's recruitment to the plasma membrane, thus promoting a spatial reorientation of domains contributing to inhibition, were also recognized. Genotype–phenotype analysis confirmed our previous observations, establishing a high frequency of ectodermal anomalies and a low prevalence of cognitive impairment and reduced growth. Finally, mutation analysis performed on cohorts of individuals with nonsyndromic pulmonic stenosis, atrial septal defects, and ventricular septal defects excluded a major contribution of germline SOS1 lesions to the isolated occurrence of these cardiac anomalies. Hum Mutat 32:760–772, 2011. © 2011 Wiley-Liss, Inc.
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Affiliation(s)
- Francesca Lepri
- IRCCS Casa Sollievo della Sofferenza, Laboratorio Mendel, San Giovanni Rotondo, Italy
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81
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Stevenson DA, Yang FC. The musculoskeletal phenotype of the RASopathies. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2011; 157C:90-103. [DOI: 10.1002/ajmg.c.30296] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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82
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Rauen KA, Banerjee A, Bishop WR, Lauchle JO, McCormick F, McMahon M, Melese T, Munster PN, Nadaf S, Packer RJ, Sebolt-Leopold J, Viskochil DH. Costello and cardio-facio-cutaneous syndromes: Moving toward clinical trials in RASopathies. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2011; 157C:136-46. [PMID: 21495172 DOI: 10.1002/ajmg.c.30294] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The RASopathies, one of the largest groups of multiple congenital anomaly syndromes known, are caused by germline mutations in various genes encoding components of the Ras/mitogen-activated protein kinase (MAPK) pathway. The RASopathies have many overlapping characteristics, including craniofacial manifestations, cardiac malformations, cutaneous, musculoskeletal, gastrointestinal, and ocular abnormalities, neurocognitive impairment, hypotonia, and an increased risk of developing cancer. Costello syndrome (CS) and cardio-facio-cutaneous (CFC) syndrome are two of the more rare RASopathies. CS is caused by activating mutations in HRAS, and CFC is caused by dysregulation of signaling in the Ras/MAPK pathway due to mutations in BRAF, MEK1, or MEK2. The Ras/MAPK pathway, which has been well-studied in cancer, is an attractive target for inhibition in the treatment of various malignancies utilizing small molecule therapeutics that specifically inhibit the pathway. With many inhibitors of the Ras/MAPK pathway in clinical trials, the notion of using these molecules to ameliorate developmental defects in CS and CFC is under consideration. CS and CFC, like other syndromes in their class, have a progressive phenotype and may be amenable to inhibition or normalization of signaling.
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Affiliation(s)
- Katherine A Rauen
- Division of Medical Genetics at the University of California at San Francisco, USA.
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83
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Dhandapany PS, Fabris F, Tonk R, Illaste A, Karakikes I, Sorourian M, Sheng J, Hajjar RJ, Tartaglia M, Sobie EA, Lebeche D, Gelb BD. Cyclosporine attenuates cardiomyocyte hypertrophy induced by RAF1 mutants in Noonan and LEOPARD syndromes. J Mol Cell Cardiol 2011; 51:4-15. [PMID: 21440552 DOI: 10.1016/j.yjmcc.2011.03.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 02/11/2011] [Accepted: 03/01/2011] [Indexed: 02/08/2023]
Abstract
RAS activation is implicated in physiologic and pathologic cardiac hypertrophy. Cross-talk between the Ras and calcineurin pathways, the latter also having been implicated in cardiac hypertrophy, has been suspected for pathologic hypertrophy. Our recent discovery that germ-line mutations in RAF1, which encodes a downstream RAS effector, cause Noonan and LEOPARD syndromes with a high prevalence of hypertrophic cardiomyopathy provided an opportunity to elaborate the role of RAF1 in cardiomyocyte biology. Here, we characterize the role of RAF1 signaling in cardiomyocyte hypertrophy with an aim of identifying potential therapeutic targets. We modeled hypertrophic cardiomyopathy by infecting neonatal and adult rat cardiomyocytes (NRCMs and ARCMs, respectively) with adenoviruses encoding wild-type RAF1 and three Noonan/LEOPARD syndrome-associated RAF1 mutants (S257L, D486N or L613V). These RAF1 proteins, except D486N, engendered cardiomyocyte hypertrophy. Surprisingly, these effects were independent and dependent of mitogen activated protein kinases in NRCMs and ARCMs, respectively. Inhibiting Mek1/2 in RAF1 overexpressing cells blocked hypertrophy in ARCMs but not in NRCMs. Further, we found that endogenous and heterologously expressed RAF1 complexed with calcineurin, and RAF1 mutants causing hypertrophy signaled via nuclear factor of activated T cells (Nfat) in both cell types. The involvement of calcineurin was also reflected by down regulation of Serca2a and dysregulation of calcium signaling in NRCMs. Furthermore, treatment with the calcineurin inhibitor cyclosporine blocked hypertrophy in NRCMs and ARCMs overexpressing RAF1. Thus, we have identified calcineurin as a novel interaction partner for RAF1 and established a mechanistic link and possible therapeutic target for pathological cardiomyocyte hypertrophy induced by mutant RAF1. This article is part of a Special Issue entitled 'Possible Editorial'.
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Affiliation(s)
- Perundurai S Dhandapany
- Departments of Pediatrics and Genetics and Genomic Sciences and the Child Health and Development Institute, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA
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84
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Wu X, Simpson J, Hong JH, Kim KH, Thavarajah NK, Backx PH, Neel BG, Araki T. MEK-ERK pathway modulation ameliorates disease phenotypes in a mouse model of Noonan syndrome associated with the Raf1(L613V) mutation. J Clin Invest 2011; 121:1009-25. [PMID: 21339642 DOI: 10.1172/jci44929] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2010] [Accepted: 12/15/2010] [Indexed: 12/30/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is a leading cause of sudden death in children and young adults. Abnormalities in several signaling pathways are implicated in the pathogenesis of HCM, but the role of the RAS-RAF-MEK-ERK MAPK pathway has been controversial. Noonan syndrome (NS) is one of several autosomal-dominant conditions known as RASopathies, which are caused by mutations in different components of this pathway. Germline mutations in RAF1 (which encodes the serine-threonine kinase RAF1) account for approximately 3%-5% of cases of NS. Unlike other NS alleles, RAF1 mutations that confer increased kinase activity are highly associated with HCM. To explore the pathogenesis of such mutations, we generated knockin mice expressing the NS-associated Raf1(L613V) mutation. Like NS patients, mice heterozygous for this mutation (referred to herein as L613V/+ mice) had short stature, craniofacial dysmorphia, and hematologic abnormalities. Valvuloseptal development was normal, but L613V/+ mice exhibited eccentric cardiac hypertrophy and aberrant cardiac fetal gene expression, and decompensated following pressure overload. Agonist-evoked MEK-ERK activation was enhanced in multiple cell types, and postnatal MEK inhibition normalized the growth, facial, and cardiac defects in L613V/+ mice. These data show that different NS genes have intrinsically distinct pathological effects, demonstrate that enhanced MEK-ERK activity is critical for causing HCM and other RAF1-mutant NS phenotypes, and suggest a mutation-specific approach to the treatment of RASopathies.
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Affiliation(s)
- Xue Wu
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
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85
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Marin TM, Keith K, Davies B, Conner DA, Guha P, Kalaitzidis D, Wu X, Lauriol J, Wang B, Bauer M, Bronson R, Franchini KG, Neel BG, Kontaridis MI. Rapamycin reverses hypertrophic cardiomyopathy in a mouse model of LEOPARD syndrome-associated PTPN11 mutation. J Clin Invest 2011; 121:1026-43. [PMID: 21339643 DOI: 10.1172/jci44972] [Citation(s) in RCA: 200] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2009] [Accepted: 08/31/2010] [Indexed: 02/06/2023] Open
Abstract
LEOPARD syndrome (LS) is an autosomal dominant "RASopathy" that manifests with congenital heart disease. Nearly all cases of LS are caused by catalytically inactivating mutations in the protein tyrosine phosphatase (PTP), non-receptor type 11 (PTPN11) gene that encodes the SH2 domain-containing PTP-2 (SHP2). RASopathies typically affect components of the RAS/MAPK pathway, yet it remains unclear how PTPN11 mutations alter cellular signaling to produce LS phenotypes. We therefore generated knockin mice harboring the Ptpn11 mutation Y279C, one of the most common LS alleles. Ptpn11(Y279C/+) (LS/+) mice recapitulated the human disorder, with short stature, craniofacial dysmorphia, and morphologic, histologic, echocardiographic, and molecular evidence of hypertrophic cardiomyopathy (HCM). Heart and/or cardiomyocyte lysates from LS/+ mice showed enhanced binding of Shp2 to Irs1, decreased Shp2 catalytic activity, and abrogated agonist-evoked Erk/Mapk signaling. LS/+ mice also exhibited increased basal and agonist-induced Akt and mTor activity. The cardiac defects in LS/+ mice were completely reversed by treatment with rapamycin, an inhibitor of mTOR. Our results demonstrate that LS mutations have dominant-negative effects in vivo, identify enhanced mTOR activity as critical for causing LS-associated HCM, and suggest that TOR inhibitors be considered for treatment of HCM in LS patients.
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Affiliation(s)
- Talita M Marin
- Department of Medicine, Division of Cardiology, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02115, USA
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