title: Multimodular biosensors reveal a novel platform for activation of G proteins by growth factor receptors.
abstract: Environmental cues are transmitted to the interior of the cell via a complex network of signaling hubs. Receptor tyrosine kinases (RTKs) and trimeric G proteins are two such major signaling hubs in eukaryotes. Conventionally, canonical signal transduction via trimeric G proteins is thought to be triggered exclusively by G protein-coupled receptors. Here we used molecular engineering to develop modular fluorescent biosensors that exploit the remarkable specificity of bimolecular recognition, i.e., of both G proteins and RTKs, and reveal the workings of a novel platform for activation of G proteins by RTKs in single living cells. Comprised of the unique modular makeup of guanidine exchange factor Gα-interacting vesicle-associated protein (GIV)/girdin, a guanidine exchange factor that links G proteins to a variety of RTKs, these biosensors provide direct evidence that RTK-GIV-Gαi ternary complexes are formed in living cells and that Gαi is transactivated within minutes after growth factor stimulation at the plasma membrane. Thus, GIV-derived biosensors provide a versatile strategy for visualizing, monitoring, and manipulating the dynamic association of Gαi with RTKs for noncanonical transactivation of G proteins in cells and illuminate a fundamental signaling event regulated by GIV during diverse cellular processes and pathophysiologic states.
authors.affiliation: Departments of Medicine and.
authors.forename: Krishna K
authors.initials: KK
authors.lastname: Midde
authors.affiliation: Departments of Medicine and.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Aznar
authors.affiliation: Departments of Medicine and.
authors.forename: Melanie B
authors.initials: MB
authors.lastname: Laederich
authors.affiliation: Departments of Medicine and.
authors.forename: Gary S
authors.initials: GS
authors.lastname: Ma
authors.affiliation: Pharmacology and.
authors.forename: Maya T
authors.initials: MT
authors.lastname: Kunkel
authors.affiliation: Pharmacology and.
authors.forename: Alexandra C
authors.initials: AC
authors.lastname: Newton
authors.affiliation: Departments of Medicine and Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093 prghosh@ucsd.edu.
authors.forename: Pradipta
authors.initials: P
authors.lastname: Ghosh
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D019556:COS Cells; D002522:Chlorocebus aethiops; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D017978:Receptors, Growth Factor / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C502451:CCDC88A protein, human; D008840:Microfilament Proteins; D017978:Receptors, Growth Factor; D033921:Vesicular Transport Proteins; D020794:Receptor Protein-Tyrosine Kinases; D019204:GTP-Binding Proteins
keywords: Akt; Girdin; PI3-kinase; cyclic AMP; growth factor receptor tyrosine kinase; heterotrimeric G protein; invasion