The neurofibromin recruitment factor Spred1 binds to the GAP related domain without affecting Ras inactivation.
Neurofibromatosis type 1 (NF1) and Legius syndrome are related diseases with partially overlapping symptoms caused by alterations of the tumor suppressor genes NF1 (encoding the protein neurofibromin) and SPRED1 (encoding sprouty-related, EVH1 domain-containing protein 1, Spred1), respectively. Both proteins are negative regulators of Ras/MAPK signaling with neurofibromin functioning as a Ras-specific GTPase activating protein (GAP) and Spred1 acting on hitherto undefined components of the pathway. Importantly, neurofibromin has been identified as a key protein in the development of cancer, as it is genetically altered in a large number of sporadic human malignancies unrelated to NF1. Spred1 has previously been demonstrated to interact with neurofibromin via its N-terminal Ena/VASP Homology 1 (EVH1) domain and to mediate membrane translocation of its target dependent on its C-terminal Sprouty domain. However, the region of neurofibromin required for the interaction with Spred1 has remained unclear. Here we show that the EVH1 domain of Spred1 binds to the noncatalytic (GAPex) portion of the GAP-related domain (GRD) of neurofibromin. Binding is compatible with simultaneous binding of Ras and does not interfere with GAP activity. Our study points to a potential targeting function of the GAPex subdomain of neurofibromin that is present in all known canonical RasGAPs.
Division of Biological Chemistry, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria;
Theresia
T
Dunzendorfer-Matt
Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94158;
Ellen L
EL
Mercado
Division of Medical Biochemistry, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria.
Karl
K
Maly
Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, CA 94158; frank.mccormick@ucsf.edu klaus.scheffzek@i-med.ac.at.
Frank
F
McCormick
Division of Biological Chemistry, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria; frank.mccormick@ucsf.edu klaus.scheffzek@i-med.ac.at.
Klaus
K
Scheffzek
D048868:Adaptor Proteins, Signal Transducing; D057809:HEK293 Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D025542:Neurofibromin 1 / Q000378:metabolism*; D000072417:Protein Domains; D018631:ras Proteins / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D025542:Neurofibromin 1; C504812:SPRED1 protein, human; D018631:ras Proteins
RASopathy; cancer; nontruncating mutations; protein–protein interaction; signal transduction