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Updated: Apr 3, 2026

Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
Published on: March 9, 2012
SARA and RNF11 interact with each other and ESCRT-0 core proteins and regulate degradative EGFR trafficking
E Kostaras1, G Sflomos, N M Pedersen
11] Laboratory of Biological Chemistry, Medical School, University of Ioannina, Ioannina, Greece [2] Department of Biomedical Research, Foundation for Research and Technology-Hellas, Institute of Molecular Biology and Biotechnology, University Campus of Ioannina, Ioannina, Greece.
Smad anchor for receptor activation (SARA) and RNF11 regulate epidermal growth factor receptor (EGFR) degradation. Their dysfunction delays EGFR degradation, impacting cancer signaling pathways.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Smad anchor for receptor activation (SARA) binds phosphatidylinositol 3-phosphates via its FYVE domain, localizing to endocytic membranes.
- SARA was initially identified for its role in recruiting SMAD2/3 to TGFβ receptors but is also implicated in endocytic trafficking.
Purpose of the Study:
- To investigate the role of the ubiquitin ligase RNF11 as a SARA-interacting protein in endocytic trafficking and receptor degradation.
- To elucidate the functional relationship between RNF11, SARA, and the Endosomal Sorting Complexes Required for Transport (ESCRT) machinery.
Main Methods:
- Co-immunoprecipitation to identify interacting proteins.
- Gain- and loss-of-function studies using RNF11 and SARA perturbations.
- Analysis of epidermal growth factor receptor (EGFR) degradation and ERK1/2 phosphorylation.
Main Results:
- RNF11 and SARA interact with ESCRT-0 subunits (STAM2, Eps15b) and Hrs.
- Perturbation of RNF11 and SARA levels delays EGFR degradation and alters EGF-induced ERK1/2 phosphorylation.
- SARA interacts with clathrin, ESCRT-I (Tsg101), and ubiquitinated cargo, suggesting a potential substitute for Hrs in ESCRT-0 complexes.
Conclusions:
- RNF11 and SARA are integral components of ESCRT-0 complexes, participating in the ESCRT-dependent lysosomal degradation of receptors.
- Dysfunctional RNF11 and SARA impair lysosomal degradation of EGFRs, potentially contributing to oncogenic signaling in cancers with RNF11 overexpression.
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