Abstract

Scaffold proteins play a critical role in controlling the activity of the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway. Shoc2 is a leucine-rich repeat scaffold protein that acts as a positive modulator of ERK1/2 signaling. However, the precise mechanism by which Shoc2 modulates the activity of the ERK1/2 pathway is unclear. Here we report the identification of the E3 ubiquitin ligase HUWE1 as a binding partner and regulator of Shoc2 function. HUWE1 mediates ubiquitination and, consequently, the levels of Shoc2. Additionally, we show that both Shoc2 and HUWE1 are necessary to control the levels and ubiquitination of the Shoc2 signaling partner, RAF-1. Depletion of HUWE1 abolishes RAF-1 ubiquitination, with corresponding changes in ERK1/2 pathway activity occurring. Our results indicate that the HUWE1-mediated ubiquitination of Shoc2 is the switch that regulates the transition from an active to an inactive state of the RAF-1 kinase. Taken together, our results demonstrate that HUWE1 is a novel player involved in regulating ERK1/2 signal transmission through the Shoc2 scaffold complex.

Document Type

Article

Publication Date

10-2014

Notes/Citation Information

Published in Molecular and Cellular Biology, v. 34, no. 19, p. 3579-3593.

Copyright © 2014, American Society for Microbiology. All Rights Reserved.

The copyright holders have granted the permission for posting the article here.

Digital Object Identifier (DOI)

http://dx.doi.org/10.1128/MCB.00811-14

Funding Information

The cores mentioned above are supported in part by a grant from the National Institute of General Medical Sciences (P20GM103486). This project was supported in part by grants from the National Cancer Institute (R00CA126161 to E.G.), the National Institute of General Medical Sciences (P20GM103486), and the National Institute of Neurological Disorders and Stroke (R01NS070899 to M.S.G.) and by an American Heart Association postdoctoral award (12POST12030381 to V.D.).

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Supplemental File: Supplemental text and Fig. S1 (Immunoblotting of GST-Shoc2 immunoprecipitates), S2 (Shoc2 ubiquitination), S3 (Expression of HUWE1, RAF-1, and Shoc2), S4 (Expression of Shoc2, HUWE1, RAF-1, pERK1/2, total ERK1/2, and GAPDH), S5 (Shoc2 ubiquitination at Lys 369), and S6 (Protein expression and cell viability)

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