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The (AAA+) ATPases PSMC5 and VCP/p97 control ERK1/2 signals transmitted through the Shoc2 scaffolding complex
Author(s) -
Galperin Emilia,
Jang Eun Ryoung,
Anderson Daniel,
Jang HyeIn
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.930.1
Subject(s) - scaffold protein , ubiquitin ligase , ubiquitin , biology , microbiology and biotechnology , aaa proteins , atpase , computational biology , signal transduction , genetics , biochemistry , enzyme , gene
Signaling scaffolds guide the flow of information and the spatial organization of the enzymes within the ERK1/2 signaling pathway. However, mechanisms that control assembly and dynamics within scaffolding complexes as well as mechanisms regulating the cellular distribution of these complexes remain largely unknown. Our studies unravel a novel, multi‐level paradigm in which allosteric modifications alter the ability of the scaffold protein Shoc2 to actively accelerate transmission of ERK1/2 signals. Shoc2 accelerates ERK1/2 signaling by means of integrating Ras and RAF‐1 into a multi‐protein complex. Germ‐line mutations in Shoc2, affecting spatial distribution of Shoc2 or its ability to assemble signaling complex, result in Noonan‐like RASopathy, a developmental disorder with a wide spectrum of symptoms. Recently we determined that the amplitude of the ERK1/2 signals transduced through the complex is fine‐tuned by the HUWE1‐mediated ubiquitination of Shoc2 and its signaling partner RAF‐1. This ubiquitination is a part of the negative feedback mechanism that actively controls ERK signals. To provide the mechanistic basis of how ubiquitination of the Shoc2 scaffold and RAF‐1 is controlled, we identified previously unknown binding partners of Shoc2, the proteins of the ubiquitin machinery (AAA+) ATPases, PSMC5 and VCP/p97. We demonstrated that both ATPases modulate ubiquitination of Shoc2 and RAF‐1 through remodeling of the complex and sequestration of the E3 ligase HUWe1 from the complex. Fluorescence microscopy and biochemical analysis were utilized to demonstrate that PSMC5 and VCP/p97 are also involved in recruitment of the Shoc2 scaffolding complexes to endosomes. Importantly, the Noonan‐like RASopathy mutation that causes aberrant distribution of Shoc2 to the plasma membrane also affects mechanisms controlling Shoc2 ubiquitination as it becomes inaccessible to PSMC5 and VCP/p97. In summary, our studies are the first to demonstrate that mechano‐enzymes PSMC5 and VCP/p97 are the novel players regulating Shoc2‐ERK1/2 signal transmission and to show that mislocalization of the Shoc2 complexes affects remodeling of the scaffolding module and may lead to the developmental pathology. Furthermore, this study makes a significant advance in our understanding of the mechanisms by which scaffolds regulate specificity and dynamics of the ERK1/2 signaling networks. Support or Funding Information R00CA126161 (NIH); R01GM113087 (NIH); RSG‐14‐172‐01‐CSM (ACS); 15PRE25090207 (AHA)