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09:58
RhoC GTPase Activation Assay
Published on: August 22, 2010
The IL-1 receptor and Rho directly associate to drive cell activation in inflammation
R Singh1, B Wang, A Shirvaikar
1Department of Medicine and Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA.
The Journal of Clinical Investigation
|June 8, 1999
Summary
Interleukin-1 (IL-1) activates RhoA, a small G protein, which physically associates with the IL-1 receptor. This interaction is crucial for IL-1-induced gene expression and cytoskeletal changes in inflammation.
Area of Science:
- Cell Biology
- Molecular Biology
- Immunology
Background:
- Interleukin-1 (IL-1) is a key mediator of inflammation.
- IL-1 signaling involves the type I IL-1 receptor (IL-1R) and downstream signaling complexes.
- Rho family GTPases regulate the actin cytoskeleton and cellular signaling.
Purpose of the Study:
- To investigate the role of Rho GTPases in IL-1 receptor signaling.
- To determine if Rho GTPases associate with the IL-1 receptor complex.
- To elucidate the functional significance of the IL-1R-RhoA interaction in IL-1-induced cellular responses.
Main Methods:
- Stimulation of HeLa cells with IL-1.
- Analysis of actin stress fiber formation and RhoA activation.
- Co-precipitation assays using GST-IL-1R fusion proteins to identify interacting partners.
- In vitro binding assays with activated RhoA and IL-1 receptor domain.
- Functional assays using dominant-inhibitory RhoA mutants and C3 transferase to assess IL-6 gene transcription and kinase activity.
Main Results:
- IL-1 stimulation induced Rho-dependent actin stress fiber formation and activated RhoA.
- The IL-1 receptor cytoplasmic domain specifically precipitated RhoA and Rac-1.
- Activated RhoA directly interacted with the IL-1 receptor cytoplasmic domain.
- Inhibition of RhoA function blocked IL-1R-mediated IL-6 gene transcription and kinase activity.
- C3 transferase inhibited IL-1R-associated kinase activity.
Conclusions:
- IL-1 activates RhoA, which physically associates with the IL-1 receptor cytoplasmic domain.
- This association is essential for IL-1-induced transcriptional activation of the IL-6 gene and associated kinase activity.
- Rho-dependent cytoskeletal reorganization may facilitate the clustering of signaling molecules required for sustained cellular activation in inflammation.
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