CNKSR1 serves as a scaffold to activate an EGFR phosphatase via exclusive interaction with RhoB-GTP

Life Sci Alliance. 2021 Jun 29;4(9):e202101095. doi: 10.26508/lsa.202101095. Print 2021 Sep.


Epidermal growth factor receptor (EGFR) and human EGFR 2 (HER2) phosphorylation drives HER2-positive breast cancer cell proliferation. Enforced activation of phosphatases for those receptors could be a therapeutic option for HER2-positive breast cancers. Here, we report that degradation of an endosomal small GTPase, RhoB, by the ubiquitin ligase complex cullin-3 (CUL3)/KCTD10 is essential for both EGFR and HER2 phosphorylation in HER2-positive breast cancer cells. Using human protein arrays produced in a wheat cell-free protein synthesis system, RhoB-GTP, and protein tyrosine phosphatase receptor type H (PTPRH) were identified as interacting proteins of connector enhancer of kinase suppressor of Ras1 (CNKSR1). Mechanistically, constitutive degradation of RhoB, which is mediated by the CUL3/KCTD10 E3 complex, enabled CNKSR1 to interact with PTPRH at the plasma membrane resulting in inactivation of EGFR phosphatase activity. Depletion of CUL3 or KCTD10 led to the accumulation of RhoB-GTP at the plasma membrane followed by its interaction with CNKSR1, which released activated PTPRH from CNKSR1. This study suggests a mechanism of PTPRH activation through the exclusive binding of RhoB-GTP to CNKSR1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Breast Neoplasms / etiology
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology
  • Carrier Proteins
  • Cell Line, Tumor
  • Cullin Proteins / metabolism
  • ErbB Receptors / agonists
  • ErbB Receptors / genetics
  • ErbB Receptors / metabolism
  • Female
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Middle Aged
  • Models, Biological
  • Phosphorylation
  • Potassium Channels, Voltage-Gated / metabolism
  • Prognosis
  • Protein Array Analysis
  • Protein Binding
  • Proteolysis
  • Receptor, ErbB-2 / genetics
  • Receptor, ErbB-2 / metabolism
  • Receptor-Like Protein Tyrosine Phosphatases, Class 3 / metabolism
  • rhoB GTP-Binding Protein / metabolism*


  • CNKSR1 protein, human
  • CUL3 protein, human
  • Carrier Proteins
  • Cullin Proteins
  • Intracellular Signaling Peptides and Proteins
  • KCTD10 protein, human
  • Potassium Channels, Voltage-Gated
  • EGFR protein, human
  • ERBB2 protein, human
  • ErbB Receptors
  • Receptor, ErbB-2
  • Receptor-Like Protein Tyrosine Phosphatases, Class 3
  • rhoB GTP-Binding Protein