GIV/Girdin activates Gαi and inhibits Gαs via the same motif.
We previously showed that guanine nucleotide-binding (G) protein α subunit (Gα)-interacting vesicle-associated protein (GIV), a guanine-nucleotide exchange factor (GEF), transactivates Gα activity-inhibiting polypeptide 1 (Gαi) proteins in response to growth factors, such as EGF, using a short C-terminal motif. Subsequent work demonstrated that GIV also binds Gαs and that inactive Gαs promotes maturation of endosomes and shuts down mitogenic MAPK-ERK1/2 signals from endosomes. However, the mechanism and consequences of dual coupling of GIV to two G proteins, Gαi and Gαs, remained unknown. Here we report that GIV is a bifunctional modulator of G proteins; it serves as a guanine nucleotide dissociation inhibitor (GDI) for Gαs using the same motif that allows it to serve as a GEF for Gαi. Upon EGF stimulation, GIV modulates Gαi and Gαs sequentially: first, a key phosphomodification favors the assembly of GIV-Gαi complexes and activates GIV's GEF function; then a second phosphomodification terminates GIV's GEF function, triggers the assembly of GIV-Gαs complexes, and activates GIV's GDI function. By comparing WT and GIV mutants, we demonstrate that GIV inhibits Gαs activity in cells responding to EGF. Consequently, the cAMP→PKA→cAMP response element-binding protein signaling axis is inhibited, the transit time of EGF receptor through early endosomes are accelerated, mitogenic MAPK-ERK1/2 signals are rapidly terminated, and proliferation is suppressed. These insights define a paradigm in G-protein signaling in which a pleiotropically acting modulator uses the same motif both to activate and to inhibit G proteins. Our findings also illuminate how such modulation of two opposing Gα proteins integrates downstream signals and cellular responses.
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093;
Vijay
V
Gupta
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093;
Deepali
D
Bhandari
Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118;
Anthony
A
Leyme
Department of Medicine, University of California, San Diego, La Jolla, CA 92093;
Nicolas
N
Aznar
Department of Medicine, University of California, San Diego, La Jolla, CA 92093;
Krishna K
KK
Midde
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093;
I-Chung
IC
Lo
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093; Department of Medicine, University of California, San Diego, La Jolla, CA 92093;
Jason
J
Ear
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093;
Ingrid
I
Niesman
Department of Medicine, University of California, San Diego, La Jolla, CA 92093;
Inmaculada
I
López-Sánchez
Department of Chemistry and Molecular Pharmacology, Institute for Research in Biomedicine, 08028 Barcelona, Spain;
Juan Bautista
JB
Blanco-Canosa
Department of Psychiatry, University of California, San Francisco, CA 94158.
Mark
M
von Zastrow
Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118;
Mikel
M
Garcia-Marcos
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093; mfarquhar@ucsd.edu prghosh@ucsd.edu.
Marilyn G
MG
Farquhar
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093; Department of Medicine, University of California, San Diego, La Jolla, CA 92093; mfarquhar@ucsd.edu prghosh@ucsd.edu.
Pradipta
P
Ghosh
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D049109:Cell Proliferation / Q000187:drug effects; D002633:Chemotaxis / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D051360:Cyclin-Dependent Kinase 5 / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism*; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D006160:Guanosine Triphosphate / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry / Q000378:metabolism*; D050505:Mutant Proteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D000074121:Protein Kinase C-theta / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013329:Structure-Activity Relationship; D033921:Vesicular Transport Proteins / Q000737:chemistry / Q000378:metabolism*
C502451:CCDC88A protein, human; D017362:Cyclic AMP Response Element-Binding Protein; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D008840:Microfilament Proteins; D050505:Mutant Proteins; D033921:Vesicular Transport Proteins; D004815:Epidermal Growth Factor; D006160:Guanosine Triphosphate; D000242:Cyclic AMP; D051360:Cyclin-Dependent Kinase 5; D017868:Cyclic AMP-Dependent Protein Kinases; D000074121:Protein Kinase C-theta; D048049:Extracellular Signal-Regulated MAP Kinases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D019205:GTP-Binding Protein alpha Subunits, Gs
cAMP; cancer invasion; growth factor receptor tyrosine kinase; guanine nucleotide dissociation inhibitor; heterotrimeric G proteins