Differences in the Regulation of K-Ras and H-Ras Isoforms by Monoubiquitination

Baker, Rachael; Wilkerson, Emily M.; Sumita, Kazutaka; Isom, Daniel G.; Sasaki, Atsuo T.; Dohlman, Henrik G.; Campbell, Sharon L.

doi:10.1074/jbc.c113.525691

Cited by 66 publications

(68 citation statements)

References 43 publications

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“…Ubiquitylation at K147 enhanced WT KRAS-GTP formation and a later study identified impaired GAP interaction to account for this altered property (Baker et al, 2013a). HRAS has been shown to be ubiquitylated at K117, and this modification accelerated nucleotide exchange and activation (Baker et al, 2013b). Given the differentially observed ubiquitylation patterns that have been reported between RAS isoforms, RAS ubiquitylation is likely to have distinct roles in different cell types based on the isoform and site of modification.…”

Section: Ras Isoform Differences and Post-translational Modificationsmentioning

confidence: 99%

RAS isoforms and mutations in cancer at a glance

Hobbs

Der

Rossman

2016

Journal of Cell Science

643

681

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RAS proteins (KRAS4A, KRAS4B, NRAS and HRAS) function as GDP-GTP-regulated binary on-off switches, which regulate cytoplasmic signaling networks that control diverse normal cellular processes. Gain-of-function missense mutations in RAS genes are found in ∼25% of human cancers, prompting interest in identifying anti-RAS therapeutic strategies for cancer treatment. However, despite more than three decades of intense effort, no anti-RAS therapies have reached clinical application. Contributing to this failure has been an underestimation of the complexities of RAS. First, there is now appreciation that the four human RAS proteins are not functionally identical. Second, with >130 different missense mutations found in cancer, there is an emerging view that there are mutation-specific consequences on RAS structure, biochemistry and biology, and mutation-selective therapeutic strategies are needed. In this Cell Science at a Glance article and accompanying poster, we provide a snapshot of the differences between RAS isoforms and mutations, as well as the current status of anti-RAS drug-discovery efforts.

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Section: Ras Isoform Differences and Post-translational Modificationsmentioning

confidence: 99%

RAS isoforms and mutations in cancer at a glance

Hobbs

Der

Rossman

2016

Journal of Cell Science

643

681

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“…For example, KRAS monoubiquitylation at lysine 147 up-regulates RAS activity, signaling, and tumorigenesis (6). Additionally, lysine 104 has been shown to be a minor site of ubiquitylation, and we have previously shown that ubiquitylation of KRAS at this position does not alter the intrinsic biochemical properties or regulation by GEFs and GAPs (7). In contrast, lysine 104 acetylation was reported to down-regulate KRAS G12V-driven effector signaling and growth transformation in NIH 3T3 cells (8,9).…”

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confidence: 97%

A KRAS GTPase K104Q Mutant Retains Downstream Signaling by Offsetting Defects in Regulation

Yin

Kistler

George

et al. 2017

Journal of Biological Chemistry

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Edited by Norma AllewellThe KRAS GTPase plays a critical role in the control of cellular growth. The activity of KRAS is regulated by guanine nucleotide exchange factors (GEFs), GTPase-activating proteins (GAPs), and also post-translational modification. Lysine 104 in KRAS can be modified by ubiquitylation and acetylation, but the role of this residue in intrinsic KRAS function has not been well characterized. We find that lysine 104 is important for GEF recognition, because mutations at this position impaired GEF-mediated nucleotide exchange. Because the KRAS K104Q mutant has recently been employed as an acetylation mimetic, we conducted a series of studies to evaluate its in vitro and cellbased properties. Herein, we found that KRAS K104Q exhibited defects in both GEF-mediated exchange and GAP-mediated GTP hydrolysis, consistent with NMR-detected structural perturbations in localized regions of KRAS important for recognition of these regulatory proteins. Despite the partial defect in both GEF and GAP regulation, KRAS K104Q did not alter steady-state GTP-bound levels or the ability of the oncogenic KRAS G12V mutant to cause morphologic transformation of NIH 3T3 mouse fibroblasts and of WT KRAS to rescue the growth defect of mouse embryonic fibroblasts deficient in all Ras genes. We conclude that the KRAS K104Q mutant retains both WT and mutant KRAS function, probably due to offsetting defects in recognition of factors that up-regulate (GEF) and down-regulate (GAP) RAS activity.RAS proteins function as molecular switches that cycle between active GTP-and inactive GDP-bound states to regulate signal transduction pathways that modulate cellular growth control. In the unstimulated cell, RAS proteins are populated in their inactive GDP-bound state. However, in response to growth-stimulatory signals, guanine nucleotide exchange factors (GEFs) 2 co-localize and up-regulate RAS by facilitating exchange of GDP for GTP. Inactivation of RAS is achieved through GTPase-activating proteins (GAPs) that bind to GTPbound RAS and promote GTP hydrolysis (1, 2). Several point mutations in RAS have been identified that dysregulate RAS nucleotide exchange or hydrolysis, often leading to hyperactivation and promoting tumorigenesis. The most common RAS mutations identified in cancer occur at residues 12, 13, and 61 and render RAS GAP defective, thereby populating RAS in its active GTP-bound state (3). Constitutive hyperactivation of RAS promotes chronic stimulation of effector-mediated downstream pathways, causing deregulated growth and tumorigenic growth transformation.RAS contains two dynamic regions termed switch I (SWI; residues 30 -37) and switch II (SWII; residues 60 -76 with 66 -74 corresponding to helix 2 (H2)) that populate distinct conformations when the protein is bound to GDP versus GTP. Effectors and GAP proteins recognize specific conformations of the switch regions and bind with preferential affinity to the active GTP-bound state. Activated GTP-bound RAS can interact with multiple effectors (e.g. RAF kinase, RAL exchang...

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“…We also speculate that RasG/K-Ras E3 ligase may recognize GTP-RasG/KRas, which is in the binding status with its effector, to specifically regulate effector pathway. This could be analogous mechanism to the ubiquitin-mediate effector selection of Ras, which we have reported recently (14,39,45). We expect that active RasG-specific E3 ligase has a role in cytokinesis, based on our observation.…”

Section: H-ras Homologue Rasc Does Not Undergo Ubiquitination-mentioning

confidence: 83%

Degradation of Activated K-Ras Orthologue via K-Ras-specific Lysine Residues Is Required for Cytokinesis

Sumita

Yoshino

Sasaki

et al. 2014

Journal of Biological Chemistry

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Background: Targeting oncogenic K-Ras for cancer therapy has remained challenging. Results: Ubiquitination specifically occurs on the activated K-Ras orthologue in Dictyostelium via evolutionary conserved K-Ras lysines, which promotes K-Ras protein degradation. Conclusion:Our results indicate the existence of GTP-loaded K-Ras orthologue-specific degradation system in Dictyostelium. Significance: This work reveals a novel negative feedback regulation for the K-Ras isoform, which is critical for cytokinesis in Dictyostelium.

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Differences in the Regulation of K-Ras and H-Ras Isoforms by Monoubiquitination

Cited by 66 publications

References 43 publications

RAS isoforms and mutations in cancer at a glance

RAS isoforms and mutations in cancer at a glance

A KRAS GTPase K104Q Mutant Retains Downstream Signaling by Offsetting Defects in Regulation

Degradation of Activated K-Ras Orthologue via K-Ras-specific Lysine Residues Is Required for Cytokinesis

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