Nucleophosmin and nucleolin regulate K-Ras plasma membrane interactions and MAPK signal transduction.
The spatial organization of Ras proteins into nanoclusters on the inner leaflet of the plasma membrane is essential for high fidelity signaling through the MAPK pathway. Here we identify two selective regulators of K-Ras nanoclustering from a proteomic screen for K-Ras interacting proteins. Nucleophosmin (NPM) and nucleolin are predominantly localized to the nucleolus but also have extranuclear functions. We show that a subset of NPM and nucleolin localizes to the inner leaflet of plasma membrane and forms specific complexes with K-Ras but not other Ras isoforms. Active GTP-loaded and inactive GDP-loaded K-Ras both interact with NPM, although NPM-K-Ras binding is increased by growth factor receptor activation. NPM and nucleolin both stabilize K-Ras levels on the plasma membrane, but NPM concurrently increases the clustered fraction of GTP-K-Ras. The increase in nanoclustered GTP-K-Ras in turn enhances signal gain in the MAPK pathway. In summary these results reveal novel extranucleolar functions for NPM and nucleolin as regulators of K-Ras nanocluster formation and activation of the MAPK pathway. The study also identifies a new class of K-Ras nanocluster regulator that operates independently of the structural scaffold galectin-3.
Inder
Kerry L
KL
Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia.
Lau
Chiyan
C
Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia.
Loo
Dorothy
D
Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia; Diamantina Institute for Cancer, Immunology and Metabolic Medicine, Princess Alexandra Hospital, University of Queensland, Brisbane 4102, Australia.
Chaudhary
Natasha
N
Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia.
Goodall
Andrew
A
Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia.
Martin
Sally
S
Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia.
Jones
Alun
A
Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia.
van der Hoeven
Dharini
D
Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas 77030.
Parton
Robert G
RG
Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia; Centre for Microscopy and Microanalysis, University of Queensland, Brisbane 4072, Australia.
Hill
Michelle M
MM
Institute for Molecular Bioscience, University of Queensland, Brisbane 4072, Australia; Diamantina Institute for Cancer, Immunology and Metabolic Medicine, Princess Alexandra Hospital, University of Queensland, Brisbane 4102, Australia. Electronic address: m.hill2@uq.edu.au.
Hancock
John F
JF
Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas 77030. Electronic address: john.f.hancock@uth.tmc.edu.
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D006224:Cricetinae; D003412:Cricetulus; D011905:Genes, ras; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D000090243:Nucleophosmin; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*; D000097796:Nucleolin
D020928:Mitogen-Activated Protein Kinases; D009687:Nuclear Proteins; D000090243:Nucleophosmin; D010750:Phosphoproteins; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D018631:ras Proteins; D000097796:Nucleolin; C000716967:NPM1 protein, human