Faculty Collaboration Database

Protein kinase A-dependent phosphorylation modulates beta1Pix guanine nucleotide exchange factor activity through 14-3-3beta binding. Mol Cell Biol 2008 Mar;28(5):1679-87

Date

12/28/2007

Pubmed ID

18160719

Pubmed Central ID

PMC2258773

DOI

10.1128/MCB.00898-07

Scopus ID

2-s2.0-40749160955 (requires institutional sign-in at Scopus site)   40 Citations

Abstract

beta(1)Pix is a guanine nucleotide exchange factor (GEF) for the small GTPases Rac and Cdc42 which has been shown to mediate signaling pathways leading to cytoskeletal reorganization. In the present study, we show that the basal association between endogenous betaPix and endogenous 14-3-3beta was increased after forskolin stimulation and significantly inhibited by protein kinase A inhibitor. However, forskolin stimulation failed to increase the interaction between 14-3-3beta and a beta(1)Pix mutant that is insensitive to protein kinase A phosphorylation, beta(1)Pix(S516A, T526A). We present evidence indicating that forskolin-induced binding of 14-3-3beta to beta(1)Pix results in inhibition of Rac1 GTP loading in 293 cells and in vitro. Furthermore, we show that deletion of 10 amino acid residues within the leucine zipper domain is sufficient to block beta(1)Pix homodimerization and 14-3-3beta binding and modulates beta(1)Pix-GEF activity. These residues also play a crucial role in beta(1)Pix intracellular localization. These results indicate that 14-3-3beta negatively affects the GEF activity of dimeric beta(1)Pix only. Altogether, these results provide a mechanistic insight into the role of 14-3-3beta in modulating beta(1)Pix-GEF activity.

Author List

Chahdi A, Sorokin A

Author

Andrey Sorokin PhD Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

14-3-3 Proteins
Binding Sites
Cell Cycle Proteins
Cell Line
Colforsin
Cyclic AMP-Dependent Protein Kinases
Dimerization
Electroporation
Enzyme Activation
Guanine Nucleotide Exchange Factors
Humans
Kidney
Models, Biological
Mutation
Phosphatidylinositol 3-Kinases
Phosphorylation
Precipitin Tests
Protein Binding
Protein Isoforms
Protein Structure, Tertiary
Proto-Oncogene Proteins c-myc
Recombinant Fusion Proteins
Rho Guanine Nucleotide Exchange Factors
Serine
Threonine
Time Factors
Transfection
rac1 GTP-Binding Protein