Related Experiment Videos
mDia-interacting protein acts downstream of Rho-mDia and modifies Src activation and stress fiber formation
1Department of Molecular and Cell Biology, Dokkyo University School of Medicine, Tochigi 321-0293, Japan.
Abstract:
The formin homology protein mDia is a Rho GTPase effector protein that participates in stress fiber formation, cytokinesis, and transcriptional activation of the serum response factor. Although the function of another effector of Rho, Rho-associated kinase, is well established, relatively little is known about the functional mechanism and the downstream targets of mDia. Our recent report of a Rho-mDia-Src-tyrosine kinase pathway suggested an important role for mDia in cell adhesion turnover. We identified a new mDia-interacting protein which is expressed ubiquitously. The new protein mainly binds to the proline-rich region of mDia through its Src homology 3 domain and also binds to Grb2 through its proline-rich domain. The protein is localized at the cell periphery and membrane ruffles and co-localizes with mDia. Co-expression of vSrc and the mDia-interacting protein induces significant morphological changes at focal contacts and activation of vSrc. Furthermore, we found that the mDia-interacting protein plays an important role in stress fiber formation induced by active mDia1. Our results suggest that this new protein regulates actin polymerization and cell adhesion turnover in the downstream portion of the Rho-mDia pathway by interacting with Grb2 and Src.
Insights
A newly identified protein interacts with mDia, regulating actin polymerization and cell adhesion turnover. This discovery sheds light on the downstream mechanisms of the Rho-mDia pathway.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- The formin mDia protein is a key effector of Rho GTPase, involved in cell processes like stress fiber formation and cytokinesis.
- While Rho-associated kinase's function is known, mDia's mechanism and targets remain less understood.
- Previous research indicated mDia's role in cell adhesion turnover via a Rho-mDia-Src pathway.
Purpose of the Study:
- To identify and characterize novel mDia-interacting proteins.
- To elucidate the functional role of a newly discovered mDia-interacting protein in cellular processes.
- To investigate the protein's involvement in the Rho-mDia signaling pathway.
Main Methods:
- Protein interaction studies to identify mDia-binding partners.
- Co-localization experiments to determine subcellular localization.
- Co-expression studies with vSrc to assess functional impact.
- Analysis of stress fiber formation and cell adhesion dynamics.
Main Results:
- A novel ubiquitously expressed protein interacting with mDia was identified.
- This protein binds mDia via its SH3 domain and Grb2 via its proline-rich domain.
- The protein localizes to the cell periphery and membrane ruffles, co-localizing with mDia.
- Co-expression with vSrc induced morphological changes and vSrc activation.
- The identified protein is crucial for mDia1-induced stress fiber formation.
Conclusions:
- The newly identified protein acts as a regulator of actin polymerization and cell adhesion turnover.
- It functions downstream in the Rho-mDia pathway, integrating signals from Grb2 and Src.
- This discovery provides new insights into the molecular mechanisms governing cell adhesion and cytoskeleton dynamics.