Cyclic Nucleotide-dependent Protein Kinases Target ARHGAP17 and ARHGEF6 Complexes in Platelets.
J Biol Chem
; 290(50): 29974-83, 2015 Dec 11.
Article
en En
| MEDLINE
| ID: mdl-26507661
Endothelial cells release prostacyclin (PGI2) and nitric oxide (NO) to inhibit platelet functions. PGI2 and NO effects are mediated by cyclic nucleotides, cAMP- and cGMP-dependent protein kinases (PKA, PKG), and largely unknown PKA and PKG substrate proteins. The small G-protein Rac1 plays a key role in platelets and was suggested to be a target of cyclic nucleotide signaling. We confirm that PKA and PKG activation reduces Rac1-GTP levels. Screening for potential mediators of this effect resulted in the identification of the Rac1-specific GTPase-activating protein ARHGAP17 and the guanine nucleotide exchange factor ARHGEF6 as new PKA and PKG substrates in platelets. We mapped the PKA/PKG phosphorylation sites to serine 702 on ARHGAP17 using Phos-tag gels and to serine 684 on ARHGEF6. We show that ARHGAP17 binds to the actin-regulating CIP4 protein in platelets and that Ser-702 phosphorylation interferes with this interaction. Reduced CIP4 binding results in enhanced inhibition of cell migration by ARHGAP17. Furthermore, we show that ARHGEF6 is constitutively linked to GIT1, a GAP of Arf family small G proteins, and that ARHGEF6 phosphorylation enables binding of the 14-3-3 adaptor protein to the ARHGEF6/GIT1 complex. PKA and PKG induced rearrangement of ARHGAP17- and ARHGEF6-associated protein complexes might contribute to Rac1 regulation and platelet inhibition.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Plaquetas
/
Proteínas Quinasas Dependientes de GMP Cíclico
/
Proteínas Quinasas Dependientes de AMP Cíclico
/
Proteínas Activadoras de GTPasa
Tipo de estudio:
Prognostic_studies
Límite:
Humans
Idioma:
En
Revista:
J Biol Chem
Año:
2015
Tipo del documento:
Article
País de afiliación:
Irlanda
Pais de publicación:
Estados Unidos