101
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Cirstea IC, Gremer L, Dvorsky R, Zhang SC, Piekorz RP, Zenker M, Ahmadian MR. Diverging gain-of-function mechanisms of two novel KRAS mutations associated with Noonan and cardio-facio-cutaneous syndromes. Hum Mol Genet 2012; 22:262-70. [PMID: 23059812 DOI: 10.1093/hmg/dds426] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Activating somatic and germline mutations of closely related RAS genes (H, K, N) have been found in various types of cancer and in patients with developmental disorders, respectively. The involvement of the RAS signalling pathways in developmental disorders has recently emerged as one of the most important drivers in RAS research. In the present study, we investigated the biochemical and cell biological properties of two novel missense KRAS mutations (Y71H and K147E). Both mutations affect residues that are highly conserved within the RAS family. KRAS(Y71H) showed no clear differences to KRAS(wt), except for an increased binding affinity for its major effector, the RAF1 kinase. Consistent with this finding, even though we detected similar levels of active KRAS(Y71H) when compared with wild-type protein, we observed an increased activation of MEK1/2, irrespective of the stimulation conditions. In contrast, KRAS(K147E) exhibited a tremendous increase in nucleotide dissociation generating a self-activating RAS protein that can act independently of upstream signals. As a consequence, levels of active KRAS(K147E) were strongly increased regardless of serum stimulation and similar to the oncogenic KRAS(G12V). In spite of this, KRAS(K147E) downstream signalling did not reach the level triggered by oncogenic KRAS(G12V), especially because KRAS(K147E) was downregulated by RASGAP and moreover exhibited a 2-fold lower affinity for RAF kinase. Here, our findings clearly emphasize that individual RAS mutations, despite being associated with comparable phenotypes of developmental disorders in patients, can cause remarkably diverse biochemical effects with a common outcome, namely a rather moderate gain-of-function.
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Affiliation(s)
- Ion C Cirstea
- Institute of Biochemistry & Molecular Biology II, Heinrich-Heine University, Düsseldorf 40225, Germany
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102
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Martinelli S, Nardozza AP, Delle Vigne S, Sabetta G, Torreri P, Bocchinfuso G, Flex E, Venanzi S, Palleschi A, Gelb BD, Cesareni G, Stella L, Castagnoli L, Tartaglia M. Counteracting effects operating on Src homology 2 domain-containing protein-tyrosine phosphatase 2 (SHP2) function drive selection of the recurrent Y62D and Y63C substitutions in Noonan syndrome. J Biol Chem 2012; 287:27066-77. [PMID: 22711529 PMCID: PMC3411048 DOI: 10.1074/jbc.m112.350231] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Activating mutations in PTPN11 cause Noonan syndrome, the most common nonchromosomal disorder affecting development and growth. PTPN11 encodes SHP2, an Src homology 2 (SH2) domain-containing protein-tyrosine phosphatase that positively modulates RAS function. Here, we characterized functionally all possible amino acid substitutions arising from single-base changes affecting codons 62 and 63 to explore the molecular mechanisms lying behind the largely invariant occurrence of the Y62D and Y63C substitutions recurring in Noonan syndrome. We provide structural and biochemical data indicating that the autoinhibitory interaction between the N-SH2 and protein-tyrosine phosphatase (PTP) domains is perturbed in both mutants as a result of an extensive structural rearrangement of the N-SH2 domain. Most mutations affecting Tyr63 exerted an unpredicted disrupting effect on the structure of the N-SH2 phosphopeptide-binding cleft mediating the interaction of SHP2 with signaling partners. Among all the amino acid changes affecting that codon, the disease-causing mutation was the only substitution that perturbed the stability of the inactive conformation of SHP2 without severely impairing proper phosphopeptide binding of N-SH2. On the other hand, the disruptive effect of the Y62D change on the autoinhibited conformation of the protein was balanced, in part, by less efficient binding properties of the mutant. Overall, our data demonstrate that the selection-by-function mechanism acting as driving force for PTPN11 mutations affecting codons 62 and 63 implies balancing of counteracting effects operating on the allosteric control of the function of SHP2.
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Affiliation(s)
- Simone Martinelli
- Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, 00161 Rome, Italy
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103
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Denayer E, Peeters H, Sevenants L, Derbent M, Fryns JP, Legius E. NRAS Mutations in Noonan Syndrome. Mol Syndromol 2012; 3:34-38. [PMID: 22855653 DOI: 10.1159/000338467] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2012] [Indexed: 01/21/2023] Open
Abstract
Noonan syndrome is a genetically heterogeneous disorder caused by mutations in PTPN11, SOS1, RAF1 and less frequently in KRAS, NRAS or SHOC2. Here, we performed mutation analysis of NRAS and SHOC2 in 115 PTPN11, SOS1, RAF1, and KRAS mutation-negative individuals. No SHOC2 mutations were found, but we identified 3 NRAS mutations in 3 probands. One NRAS mutation was novel. The phenotype associated with germline NRAS mutations is variable. Our results confirm that a small proportion of Noonan syndrome patients carry germline NRAS mutations.
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Affiliation(s)
- E Denayer
- Departments of Human Genetics Catholic University of Leuven, Leuven, Belgium
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104
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Brasil AS, Malaquias AC, Kim CA, Krieger JE, Jorge AA, Pereira AC, Bertola DR. KRAS gene mutations in Noonan syndrome familial cases cluster in the vicinity of the switch II region of the G-domain: Report of another family with metopic craniosynostosis. Am J Med Genet A 2012; 158A:1178-84. [DOI: 10.1002/ajmg.a.35270] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 01/12/2012] [Indexed: 12/12/2022]
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105
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Gripp KW, Hopkins E, Serrano A, Leonard NJ, Stabley DL, Sol-Church K. Transmission of the rare HRAS mutation (c. 173C > T; p.T58I) further illustrates its attenuated phenotype. Am J Med Genet A 2012; 158A:1095-101. [PMID: 22488832 DOI: 10.1002/ajmg.a.35294] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 12/29/2011] [Indexed: 01/17/2023]
Abstract
Costello syndrome was delineated based on its distinctive phenotype including severe failure-to-thrive with macrocephaly, characteristic facial features, hypertrophic cardiomyopathy, papillomata, malignant tumors, and cognitive impairment. Heterozygous germline mutations in the proto-oncogene HRAS cause Costello syndrome, and its inheritance pattern would thus be autosomal dominant. With exception of two instances of parental mosaicism, one presumed gonadal and the other proven somatic mosaicism for the p.G12S change, all published cases resulted from de novo mutations, typically arising in the paternal germline. More than 90% of these mutations affect the glycine residues in position 12 or 13, and result in a gain-of-function of the altered protein. A rare heterozygous HRAS alteration (c.173C > T; p.T58I) associated with an attenuated phenotype was previously reported in one patient. We identified two additional individuals with this mutation, father and son. Further studies supported origin of the alteration in the grand-paternal germline. Transmission of the mutation underscores its attenuated phenotype compatible with reproduction. We reviewed the phenotype in the newly identified individuals (Patient 1, 2) and include updated information on the first previously reported individual with HRAS p.T58I (Patient 3). Macrocephaly was present in all three. Cardiac findings included hypertrophic cardiomyopathy with double-chambered right ventricle; or mitral valve prolapse in one patient each. While subtle neurologic abnormalities or developmental delay were present in all, only one showed significant cognitive and functional impairment. None developed papillomata or a malignant tumor. Genetic counseling for Costello syndrome needs to take into consideration the particular HRAS mutation.
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Affiliation(s)
- Karen W Gripp
- Division of Medical Genetics, A I duPont Hospital for Children, Wilmington, Delaware 19803, USA.
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106
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C4ST-1/CHST11-controlled chondroitin sulfation interferes with oncogenic HRAS signaling in Costello syndrome. Eur J Hum Genet 2012; 20:870-7. [PMID: 22317973 DOI: 10.1038/ejhg.2012.12] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Costello syndrome is a pediatric genetic disorder linked to oncogenic germline mutations in the HRAS gene. The disease is characterized by multiple developmental abnormalities, as well as predisposition to malignancies. Our recent observation that heart tissue from patients with Costello syndrome showed a loss of the glycosaminoglycan chondroitin-4-sulfate (C4S) inspired our present study aimed to explore a functional involvement of the chondroitin sulfate (CS) biosynthesis gene Carbohydrate sulfotransferase 11/Chondroitin-4-sulfotransferase-1 (CHST11/C4ST-1), as well as an impaired chondroitin sulfation balance, as a downstream mediator of oncogenic HRAS in Costello syndrome. Here we demonstrate a loss of C4S, as well as a reduction in C4ST-1 mRNA and protein expression, in primary fibroblasts from Costello syndrome patients. We go on to show that expression of oncogenic HRAS in normal fibroblasts can repress C4ST-1 expression, whereas interference with oncogenic HRAS signaling in Costello syndrome fibroblasts elevated C4ST-1 expression, thus identifying C4ST-1 as a negatively regulated target gene of HRAS signaling. Importantly, we show that forced expression of C4ST-1 in Costello fibroblasts could rescue the proliferation and elastogenesis defects associated with oncogenic HRAS signaling in these cells. Our results indicate reduced C4ST-1 expression and chondroitin sulfation imbalance mediating the effects of oncogenic HRAS signaling in the pathogenesis of Costello syndrome. Thus, our work identifies C4ST-1-dependent chondroitin sulfation as a downstream vulnerability in oncogenic RAS signaling, which might be pharmacologically exploited in future treatments of not only Costello syndrome and other RASopathies, but also human cancers associated with activating RAS mutations.
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107
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Razzaque MA, Komoike Y, Nishizawa T, Inai K, Furutani M, Higashinakagawa T, Matsuoka R. Characterization of a novel KRAS mutation identified in Noonan syndrome. Am J Med Genet A 2012; 158A:524-32. [PMID: 22302539 DOI: 10.1002/ajmg.a.34419] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 10/02/2011] [Indexed: 12/31/2022]
Abstract
Noonan syndrome (NS) is the most common non-chromosomal syndrome seen in children and is characterized by short stature, dysmorphic facial features, chest deformity, a wide range of congenital heart defects and developmental delay of variable degree. Mutations in the Ras/mitogen-activated protein kinase (MAPK) signaling pathways cause about 70% of NS cases with a KRAS mutation present in about 2%. In a cohort of 65 clinically confirmed NS patients of Japanese origin, we screened for mutations in the RAS genes by direct sequencing. We found a novel mutation in KRAS with an amino acid substitution of asparagine to serine at codon 116 (N116S). We analyzed the biological activity of this mutant by ectopic expression of wild-type or mutant KRAS. NS-associated KRAS mutation resulted in Erk activation and active Ras-GTP levels, and exhibited mild cell proliferation. In addition, kras-targeted morpholino knocked-down zebrafish embryos caused heart and craniofacial malformations, while the expression of mutated kras resulted in maldevelopment of the heart. Our findings implicate that N116S change in KRAS is a hyperactive mutation which is a causative agent of NS through maldevelopment of the heart.
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Affiliation(s)
- Md Abdur Razzaque
- International Research and Educational Institute for Integrated Medical Sciences (IREIIMS), Tokyo Women's Medical University, Tokyo, Japan
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108
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Jaiswal M, Dubey BN, Koessmeier KT, Gremer L, Ahmadian MR. Biochemical assays to characterize Rho GTPases. Methods Mol Biol 2012; 827:37-58. [PMID: 22144266 DOI: 10.1007/978-1-61779-442-1_3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Rho GTPases act as tightly regulated molecular switches governing a large variety of critical cellular functions. Their activity is controlled by two different biochemical reactions, the GDP/GTP exchange and the GTP hydrolysis. These very slow reactions require catalysis in cells by two kinds of regulatory proteins. While the guanine nucleotide exchange factors (GEFs) activate small GTPases by stimulating the exchange of bound GDP for the cellular abundant GTP, GTPase-activating proteins (GAPs) accelerate the intrinsic rate of GTP hydrolysis by several orders of magnitude, leading to their inactivation. There are a number of methods that can be used to characterize the specificity and activity of such regulators to understand the effect of binding on the protein structure and, ultimately, to gain insights into their biological functions. This chapter describes (1) detailed protocols for the expression and purification of Rho GTPases, of -effector-binding domains, and catalytic domains of GEFs and GAPs; (2) the preparation of nucleotide-free and fluorescent nucleotide-bound Rho GTPases; and (3) methods for monitoring the intrinsic and GEF-catalyzed nucleotide exchange, the intrinsic and GAP-stimulated GTP hydrolysis, and the effector interaction with active GTPase (three alternative approaches).
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Affiliation(s)
- Mamta Jaiswal
- Medical Faculty, Institute of Biochemistry and Molecular Biology II, Heinrich-Heine University, Düsseldorf, Germany
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109
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Abstract
Somatic, gain-of-function mutations in ras genes were the first specific genetic alterations identified in human cancer about 3 decades ago. Studies during the last quarter century have characterized the Ras proteins as essential components of signaling networks controlling cellular proliferation, differentiation, or survival. The oncogenic mutations of the H-ras, N-ras, or K-ras genes frequently found in human tumors are known to throw off balance the normal outcome of those signaling pathways, thus leading to tumor development. Oncogenic mutations in a number of other upstream or downstream components of Ras signaling pathways (including membrane RTKs or cytosolic kinases) have been detected more recently in association with a variety of cancers. Interestingly, the oncogenic Ras mutations and the mutations in other components of Ras/MAPK signaling pathways appear to be mutually exclusive events in most tumors, indicating that deregulation of Ras-dependent signaling is the essential requirement for tumorigenesis. In contrast to sporadic tumors, separate studies have identified germline mutations in Ras and various other components of Ras signaling pathways that occur in specific association with a number of different familial, developmental syndromes frequently sharing common phenotypic cardiofaciocutaneous features. Finally, even without being a causative force, defective Ras signaling has been cited as a contributing factor to many other human illnesses, including diabetes and immunological and inflammatory disorders. We aim this review at summarizing and updating current knowledge on the contribution of Ras mutations and altered Ras signaling to development of various tumoral and nontumoral pathologies.
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110
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Grant BJ, Lukman S, Hocker HJ, Sayyah J, Brown JH, McCammon JA, Gorfe AA. Novel allosteric sites on Ras for lead generation. PLoS One 2011; 6:e25711. [PMID: 22046245 PMCID: PMC3201956 DOI: 10.1371/journal.pone.0025711] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 09/08/2011] [Indexed: 12/31/2022] Open
Abstract
Aberrant Ras activity is a hallmark of diverse cancers and developmental diseases. Unfortunately, conventional efforts to develop effective small molecule Ras inhibitors have met with limited success. We have developed a novel multi-level computational approach to discover potential inhibitors of previously uncharacterized allosteric sites. Our approach couples bioinformatics analysis, advanced molecular simulations, ensemble docking and initial experimental testing of potential inhibitors. Molecular dynamics simulation highlighted conserved allosteric coupling of the nucleotide-binding switch region with distal regions, including loop 7 and helix 5. Bioinformatics methods identified novel transient small molecule binding pockets close to these regions and in the vicinity of the conformationally responsive switch region. Candidate binders for these pockets were selected through ensemble docking of ZINC and NCI compound libraries. Finally, cell-based assays confirmed our hypothesis that the chosen binders can inhibit the downstream signaling activity of Ras. We thus propose that the predicted allosteric sites are viable targets for the development and optimization of new drugs.
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Affiliation(s)
- Barry J. Grant
- Center for Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail: (BG); (SL); (AG)
| | - Suryani Lukman
- Bioinformatics Institute, Agency for Science, Technology and Research, Singapore
- Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
- * E-mail: (BG); (SL); (AG)
| | - Harrison J. Hocker
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
| | - Jaqueline Sayyah
- Department of Pharmacology, University of California San Diego, La Jolla, California, United States of America
| | - Joan Heller Brown
- Department of Pharmacology, University of California San Diego, La Jolla, California, United States of America
| | - J. Andrew McCammon
- Department of Chemistry and Biochemistry, Center for Theoretical Biological Physics and Howard Hughes Medical Institute, University of California San Diego, La Jolla, California, United States of America
- Department of Pharmacology, University of California San Diego, La Jolla, California, United States of America
| | - Alemayehu A. Gorfe
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
- * E-mail: (BG); (SL); (AG)
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111
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Stark Z, Gillessen-Kaesbach G, Ryan MM, Cirstea IC, Gremer L, Ahmadian MR, Savarirayan R, Zenker M. Two novel germline KRAS mutations: expanding the molecular and clinical phenotype. Clin Genet 2011; 81:590-4. [PMID: 21797849 DOI: 10.1111/j.1399-0004.2011.01754.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Noonan and Cardio-facio-cutaneous (CFC) syndromes are characterized by typical dysmorphic features, cardiac defects, short stature, variable ectodermal anomalies, and intellectual disability. Both belong to the Ras/mitogen-activated protein kinase pathway group of disorders and clinical features overlap other related conditions, notably LEOPARD and Costello syndromes. KRAS mutations account for about 2% of reported Noonan and <5% of reported CFC cases. The mutation spectrum includes recurrent missense changes clustering in particular domains of the KRAS protein and conferring gain-of-function. We report three patients from two unrelated families with novel missense KRAS mutations, p.K147E and p.Y71H. Both mutations affect a residue which is highly conserved in KRAS and other RAS isoforms. One of the families includes a mother and son pair who represent the first report of a vertically transmitted KRAS mutation. In addition, the mother and son pair had peripheral neuropathy, complicated by Charcot arthropathy in the mother. An unusual phenotypic effect of the specific KRAS mutation or a coincidence of two independent disorders may be considered. KRAS mutation-associated phenotypes appear to be subject to considerable clinical heterogeneity. All three cases highlight the challenges of clinical assessment in KRAS mutation-positive patients, and the utility of molecular testing as an adjunct to diagnosis.
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Affiliation(s)
- Z Stark
- Genetic Health Services Victoria, Murdoch Children's Research Institute, Melbourne, Australia
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112
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Hernández-Martín A, Torrelo A. Rasopathies: Developmental Disorders That Predispose to Cancer and Skin Manifestations. ACTAS DERMO-SIFILIOGRAFICAS 2011. [DOI: 10.1016/j.adengl.2011.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
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113
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Hernández-Martín A, Torrelo A. Rasopatías: trastornos del desarrollo con predisposición al cáncer y manifestaciones cutáneas. ACTAS DERMO-SIFILIOGRAFICAS 2011; 102:402-16. [DOI: 10.1016/j.ad.2011.02.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 02/23/2011] [Accepted: 02/28/2011] [Indexed: 12/30/2022] Open
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