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RhoB mRNA is stabilized by HuR after UV light
Cara J Westmark1, Virginia B Bartleson, James S Malter
1Department of Pathology and Laboratory Medicine, Waisman Center for Developmental Disabilities, University of Wisconsin, Madison, WI 53705, USA.
Oncogene
|November 16, 2004
Summary
Ultraviolet light (UVL) stabilizes RhoB mRNA by increasing its half-life. This stabilization is mediated by the RNA-binding protein HuR, which translocates to the cytoplasm after UVL exposure, impacting apoptotic signaling.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- RhoB is a small GTP-binding protein crucial for apoptotic signal transduction.
- The 3'-untranslated region (UTR) of RhoB mRNA contains AU-rich elements (AREs) that can regulate mRNA stability.
- Ultraviolet light (UVL) is known to induce RhoB production, but the mechanism of mRNA stabilization remains unclear.
Purpose of the Study:
- To investigate the mechanism by which UVL induces RhoB mRNA stabilization.
- To identify RNA-binding proteins that interact with the RhoB 3'-UTR.
- To elucidate the role of HuR in UVL-induced RhoB mRNA regulation.
Main Methods:
- Cloning of mouse RhoB mRNA and analysis of its 3'-UTR.
- Measurement of RhoB mRNA half-life in NIH/3T3 cells and human keratinocytes after UVL exposure.
- In vitro mobility shift assays and HuR immunoprecipitations to assess HuR binding to RhoB mRNA.
- Western blot analysis and immunofluorescence to track HuR localization after UVL.
Main Results:
- UVL significantly increased the half-life of RhoB mRNA in both cell types.
- HuR was found to bind to three specific sites within the RhoB 3'-UTR.
- HuR immunoprecipitations confirmed an in vivo association between HuR and RhoB mRNA.
- UVL induced rapid nuclear-to-cytoplasmic translocation of HuR.
Conclusions:
- UVL induces stress-activated signaling pathways that lead to HuR shuttling.
- HuR-mediated stabilization of RhoB mRNA is a key mechanism in the cellular response to UVL.
- This pathway regulates RhoB expression and likely contributes to apoptotic signal transduction.