Germline Missense Mutations Affecting KRAS Isoform B Are Associated with a Severe Noonan Syndrome Phenotype

Carta, Claudio; Pantaleoni, Francesca; Bocchinfuso, Gianfranco; Stella, Lorenzo; Vasta, Isabella; Sárközy, Anna; Digilio, Cristina; Palleschi, Antonio; Pizzuti, Antonio; Grammatico, Paola; Zampino, Giuseppe; Dallapiccola, Bruno; Gelb, Bruce D.; Tartaglia, Marco

doi:10.1086/504394

Cited by 204 publications

(166 citation statements)

References 55 publications

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“…The isoforms result from various alternative splicing events, which lead to the introduction of an additional exon (isoform 2), the skipping of exons 3 and 4 (isoforms 3 and 4), and a partial loss of exons 2 and 5 (isoform 5). These events stand in contrast to the known alternative splicing of KRAS, in which the two isoforms KRASA and KRASB are the result of alternative splicing events of exon 5, whereas exons 2, 3, and 4 remain invariant (21).…”

Section: Protein Codementioning

confidence: 75%

NRAS isoforms differentially affect downstream pathways, cell growth, and cell transformation

Eisfeld

Schwind

Hoag

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Significance The members of the rat sarcoma (RAS) gene family Kirsten rat sarcoma viral oncogene homolog, Harvey rat sarcoma viral oncogene homolog, and neuroblastoma RAS viral oncogene homolog (NRAS) belong to the most extensively studied oncogenes and are central players in carcinogenesis. Since their discovery approximately 30 y ago, efforts to target their aberrant activation have not led to major breakthroughs. We herein report the discovery of four so far undescribed variants of NRAS that differ in their expression patterns and, strikingly, in their downstream effects. Our results suggest that NRAS should be studied in the context of its variants. In addition, this discovery may open opportunities to develop more efficient anticancer therapies.

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Section: Protein Codementioning

confidence: 75%

NRAS isoforms differentially affect downstream pathways, cell growth, and cell transformation

Eisfeld

Schwind

Hoag

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…Our model further predicts that K-RAS4B signaling could be modulated by mutations that directly alter the membrane interaction surfaces. Two germ-line KRAS mutations identified in Noonan and cardio-facio-cutaneous (CFC) syndrome patients, K5N (21) and D153V (22)(23)(24), were shown to induce phosphorylation of MEK1/2 more strongly than WT KRAS; however, the mechanism of their activation has remained elusive. Unlike oncogenic K-RAS mutations such as G12D, G13D, and Q61H, neither of these germ-line mutations appreciably altered intrinsic GTPase activity or nucleotide exchange or sensitivity to GAPs or guanine nucleotide exchange factors (GEFs) in solution; thus, they have been classified as mutants whose phenotypes are not explained by their biochemical properties (25,26).…”

Section: K-ras4b Activation State Determines Population Of Two Majormentioning

confidence: 99%

Oncogenic and RASopathy-associated K-RAS mutations relieve membrane-dependent occlusion of the effector-binding site

Mazhab-Jafari

Marshall

Smith

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

198

292

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K-RAS4B (Kirsten rat sarcoma viral oncogene homolog 4B) is a prenylated, membrane-associated GTPase protein that is a critical switch for the propagation of growth factor signaling pathways to diverse effector proteins, including rapidly accelerated fibrosarcoma (RAF) kinases and RAS-related protein guanine nucleotide dissociation stimulator (RALGDS) proteins. Gain-of-function KRAS mutations occur frequently in human cancers and predict poor clinical outcome, whereas germ-line mutations are associated with developmental syndromes. However, it is not known how these mutations affect K-RAS association with biological membranes or whether this impacts signal transduction. Here, we used solution NMR studies of K-RAS4B tethered to nanodiscs to investigate lipid bilayer-anchored K-RAS4B and its interactions with effector protein RAS-binding domains (RBDs). Unexpectedly, we found that the effector-binding region of activated K-RAS4B is occluded by interaction with the membrane in one of the NMR-observable, and thus highly populated, conformational states. Binding of the RAF isoform ARAF and RALGDS RBDs induced marked reorientation of K-RAS4B from the occluded state to RBD-specific effector-bound states. Importantly, we found that two Noonan syndrome-associated mutations, K5N and D153V, which do not affect the GTPase cycle, relieve the occluded orientation by directly altering the electrostatics of two membrane interaction surfaces. Similarly, the most frequent KRAS oncogenic mutation G12D also drives K-RAS4B toward an exposed configuration. Further, the D153V and G12D mutations increase the rate of association of ARAF-RBD with lipid bilayer-tethered K-RAS4B. We revealed a mechanism of K-RAS4B autoinhibition by membrane sequestration of its effector-binding site, which can be disrupted by disease-associated mutations. Stabilizing the autoinhibitory interactions between K-RAS4B and the membrane could be an attractive target for anticancer drug discovery. KRAS | nuclear magnetic resonance | lipid bilayer nanodisc | oncogenic mutation | Noonan syndrome T he K-RAS4B (Kirsten rat sarcoma viral oncogene homolog 4B) protein product of the KRAS gene undergoes posttranslational farnesylation and C-terminal processing, which, in conjunction with a poly-basic hypervariable region (HVR), targets K-RAS4B to anionic lipid rafts on the intracellular side of the plasma membrane (Fig. 1A) (1). This localization is essential for K-RAS4B function and enhances signaling fidelity (2). Although the significance of membrane tethering of K-RAS4B is well appreciated, a high-resolution map of how K-RAS4B interacts with the membrane is lacking. Because membrane-anchored RAS presents a major challenge to crystallization, current structural insights into the behavior of membrane-anchored RAS have come from a variety of lower-resolution techniques including in vivo FRET-based studies (3), fluorescence and infrared spectroscopic studies (4-6), and in silico models (3). These pioneering studies suggested that the K-RAS4B GTPase domain adopts certain p...

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“…His parents declined autopsy examination. [Aoki et al, 2005;Estep et al, 2006;Kerr et al, 2006], three with neuroblastoma [Aoki et al, 2005;Zampino et al, 2007;van der Burgt et al, 2007], one with transitional cell carcinoma , and two unspecified tumors [Zampino et al, 2006]. Congenital heart defects.…”

Section: Deathsmentioning

confidence: 99%

Clinical, pathological, and molecular analyses of cardiovascular abnormalities in Costello syndrome: A Ras/MAPK pathway syndrome

Lin

Alexander

Colan

et al. 2011

American J of Med Genetics Pt A

114

106

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Cardiovascular abnormalities are important features of Costello syndrome and other Ras/MAPK pathway syndromes (“RASopathies”). We conducted clinical, pathological and molecular analyses of 146 patients with an HRAS mutation including 61 enrolled in an ongoing longitudinal study and 85 from the literature. In our study, the most common (84%) HRAS mutation was p.G12S. A congenital heart defect (CHD) was present in 27 of 61 patients (44%), usually non‐progressive valvar pulmonary stenosis. Hypertrophic cardiomyopathy (HCM), typically subaortic septal hypertrophy, was noted in 37 (61%), and 5 also had a CHD (14% of those with HCM). HCM was chronic or progressive in 14 (37%), stabilized in 10 (27%), and resolved in 5 (15%) patients with HCM; follow‐up data was not available in 8 (22%). Atrial tachycardia occurred in 29 (48%). Valvar pulmonary stenosis rarely progressed and atrial septal defect was uncommon. Among those with HCM, the likelihood of progressing or remaining stable was similar (37%, 41% respectively). The observation of myocardial fiber disarray in 7 of 10 (70%) genotyped specimens with Costello syndrome is consistent with sarcomeric dysfunction. Multifocal atrial tachycardia may be distinctive for Costello syndrome. Potentially serious atrial tachycardia may present in the fetus, and may continue or worsen in about one‐fourth of those with arrhythmia, but is generally self‐limited in the remaining three‐fourths of patients. Physicians should be aware of the potential for rapid development of severe HCM in infants with Costello syndrome, and the need for cardiovascular surveillance into adulthood as the natural history continues to be delineated. © 2011 Wiley‐Liss, Inc.

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Germline Missense Mutations Affecting KRAS Isoform B Are Associated with a Severe Noonan Syndrome Phenotype

Cited by 204 publications

References 55 publications

NRAS isoforms differentially affect downstream pathways, cell growth, and cell transformation

NRAS isoforms differentially affect downstream pathways, cell growth, and cell transformation

Oncogenic and RASopathy-associated K-RAS mutations relieve membrane-dependent occlusion of the effector-binding site

Clinical, pathological, and molecular analyses of cardiovascular abnormalities in Costello syndrome: A Ras/MAPK pathway syndrome

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