PUBLICATION

The RhoA GEF Syx is a target of Rnd3 and regulated via a Raf1-like ubiquitin-related domain

Authors
Goh, L.L., and Manser, E.
ID
ZDB-PUB-100910-23
Date
2010
Source
PLoS One   5(8): pii: e12409 (Journal)
Registered Authors
Manser, Ed
Keywords
none
MeSH Terms
  • Amino Acid Sequence
  • Animals
  • Gastrulation
  • Guanine Nucleotide Exchange Factors/chemistry*
  • Guanine Nucleotide Exchange Factors/isolation & purification
  • Guanine Nucleotide Exchange Factors/metabolism*
  • HeLa Cells
  • Humans
  • Mice
  • Molecular Sequence Data
  • Protein Binding
  • Protein Structure, Tertiary
  • Proto-Oncogene Proteins c-raf/metabolism*
  • Ubiquitin/chemistry*
  • Zebrafish
  • rho GTP-Binding Proteins/chemistry
  • rho GTP-Binding Proteins/isolation & purification
  • rho GTP-Binding Proteins/metabolism*
  • rhoA GTP-Binding Protein/chemistry
  • rhoA GTP-Binding Protein/metabolism*
PubMed
20811643 Full text @ PLoS One
Abstract
BACKGROUND: Rnd3 (RhoE) protein belongs to the unique branch of Rho family GTPases that has low intrinsic GTPase activity and consequently remains constitutively active [1], [2]. The current consensus is that Rnd1 and Rnd3 function as important antagonists of RhoA signaling primarily by activating the ubiquitous p190 RhoGAP [3], but not by inhibiting the ROCK family kinases. METHODOLOGY/PRINCIPAL FINDINGS: Rnd3 is abundant in mouse embryonic stem (mES) cells and in an unbiased two-step affinity purification screen we identified a new Rnd3 target, termed synectin-binding RhoA exchange factor (Syx), by mass spectrometry. The Syx interaction with Rnd3 does not occur through the Syx DH domain but utilizes a region similar to the classic Raf1 Ras-binding domain (RBD), and most closely related to those in RGS12 and RGS14. We show that Syx behaves as a genuine effector of Rnd3 (and perhaps Rnd1), with binding characteristics similar to p190-RhoGAP. Morpholino-oligonucleotide knockdown of Syx in zebrafish at the one cell stage resulted in embryos with shortened anterior-posterior body axis: this phenotype was effectively rescued by introducing mouse Syx1b mRNA. A Rnd3-binding defective mutant of Syx1b mutated in the RBD (E164A/R165D) was more potent in rescuing the embryonic defects than wild-type Syx1b, showing that Rnd3 negatively regulates Syx activity in vivo. CONCLUSIONS/SIGNIFICANCE: This study uncovers a well defined Rnd3 effector Syx which is widely expressed and directly impacts RhoA activation. Experiments conducted in vivo indicate that Rnd3 negatively regulates Syx, and that as a RhoA-GEF it plays a key role in early embryonic cell shape changes. Thus a connection to signaling via the planar cell polarity pathway is suggested.
Genes / Markers
Figures
Show all Figures
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Antibodies
Orthology
Engineered Foreign Genes
Mapping