Related Experiment Video

Updated: Aug 7, 2026

RhoC GTPase Activation Assay
09:58

RhoC GTPase Activation Assay

Published on: August 22, 2010

PKCbeta-dependent activation of RhoA by syndecan-4 during focal adhesion formation

Athanassios Dovas1, Atsuko Yoneda, John R Couchman

  • 1Division of Biomedical Sciences, Imperial College London, London, SW7 2AZ, UK.

Journal of Cell Science
|June 22, 2006
PubMed

Insights

Syndecan-4 signaling to RhoA involves protein kinase C alpha (PKCalpha), which is crucial for maintaining cell stress fibers. PKCalpha activation is necessary for syndecan-4 to influence RhoA activity, impacting cell adhesion and structure.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Syndecan-4 is a cell surface proteoglycan involved in focal adhesions and stress fibers.
  • Previous studies suggest a complex involving syndecan-4, phosphatidylinositol 4,5-bisphosphate, and protein kinase C alpha (PKCalpha).
  • The link between PKCalpha and RhoA signaling downstream of syndecan-4 remains unclear.

Purpose of the Study:

  • To elucidate the relationship between syndecan-4, PKCalpha, and RhoA in stress fiber formation.
  • To determine if PKCalpha acts as a mediator in the syndecan-4 to RhoA signaling pathway.
  • To investigate the mechanism by which syndecan-4 clustering influences RhoA activity.

Main Methods:

  • Utilized primary rat embryo fibroblasts.
  • Employed pharmacological inhibitors and dominant-negative constructs to inhibit PKCalpha.
  • Used siRNA to downregulate protein levels of PKCalpha.
  • Activated RhoA independently using lysophosphatidic acid.
  • Assessed focal adhesion formation and stress fiber maintenance.
  • Measured RhoA GTP levels following syndecan-4 clustering.

Main Results:

  • Inhibition of PKCalpha impaired focal adhesion and stress fiber formation.
  • These effects were bypassed by direct RhoA activation, but not by syndecan-4 clustering.
  • PKCalpha inhibition blocked syndecan-4-induced increases in RhoA activity.
  • Syndecan-4 clustering elevated RhoA GTP levels in a PKCalpha-dependent manner.

Conclusions:

  • Syndecan-4 signals to RhoA through a PKCalpha-dependent pathway.
  • PKCalpha directly regulates RhoA activity in response to syndecan-4 clustering.
  • This linear pathway is essential for stress fiber formation and maintenance.

More Related Videos

Induction of Adhesion-dependent Signals Using Low-intensity Ultrasound08:51

Induction of Adhesion-dependent Signals Using Low-intensity Ultrasound

Published on: May 8, 2012

Affinity Precipitation of Active Rho-GEFs Using a GST-tagged Mutant Rho Protein (GST-RhoA(G17A)) from Epithelial Cell Lysates11:28

Affinity Precipitation of Active Rho-GEFs Using a GST-tagged Mutant Rho Protein (GST-RhoA(G17A)) from Epithelial Cell Lysates

Published on: March 31, 2012

Related Concept Videos

Intracellular Signaling Affects Focal Adhesions01:17

Intracellular Signaling Affects Focal Adhesions

Integrins act both as extracellular input receivers and as intracellular processing activators. As their name suggests, integrins are entirely integrated into the membrane structure. Their hydrophobic membrane-spanning regions interact with the phospholipid bilayer's hydrophobic region. These membrane receptors provide extracellular attachment sites for effectors like hormones and growth factors. They activate intracellular response cascades when their effectors are bound and active.
Some...
Small GTPases - Ras and Rho01:24

Small GTPases - Ras and Rho

Ras and Rho are small monomeric GTPases that act downstream of receptor tyrosine kinase (RTK) and regulate various cellular processes. These GTPases switch between active and inactive states by binding to guanine nucleotides.
Three regulatory proteins control their activity:
MAPK Signaling Cascades01:07

MAPK Signaling Cascades

Mitogen-activated protein kinase, or MAPK pathway, activates three sequential kinases to regulate cellular responses such as proliferation, differentiation, survival, and apoptosis. The canonical MAPK pathway starts with a mitogen or growth factor binding to an RTK. The activated RTKs stimulate Ras, which recruits Raf or MAP3 Kinase (MAPKKK), the first kinase of the MAPK signaling cascade. Raf further phosphorylates and activates MEK or MAP2 Kinases (MAPKK), which in turn phosphorylates MAP...
Cell Polarization by Rho Proteins01:21

Cell Polarization by Rho Proteins

Cell polarity is the asymmetric distribution of cellular and membrane components, making one side of the cell different from the other. This polarity is essential to many processes such as embryogenesis, axon migration, glucose transport across epithelial cells, and directional cell migration. A migrating cell responds to intracellular or extracellular signals via molecular cascades that reorganize the actin cytoskeleton to establish this polarity. In these cells, the Rho family proteins Cdc42,...
Assembly of Signaling Complexes01:30

Assembly of Signaling Complexes

Multiprotein signaling complexes are formed in a dynamic process involving protein-protein interactions at the cytoplasmic domain of transmembrane receptors or enzymatic and non-enzymatic proteins associated with the receptor. These complexes ensure the activation and propagation of intracellular signals that regulate cell functions.
Interaction domains in cell signaling
Interaction domains recognize exposed features of their binding partners containing post-translationally modified sequences,...
Rab Proteins01:14

Rab Proteins

Rab proteins constitute the largest family of monomeric GTPases, of which 70 members are present in humans. Rab proteins and their effectors regulate consecutive stages of vesicle transport such as vesicle transport, docking, and fusion to the correct recipient membrane.
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...