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Development and Application of Rapamycin-regulated Tyrosine Phosphatases
06:56

Development and Application of Rapamycin-regulated Tyrosine Phosphatases

Published on: September 6, 2024

Rap2B-dependent stimulation of phospholipase C-epsilon by epidermal growth factor receptor mediated by c-Src

Matthias B Stope1, Frank Vom Dorp, Daniel Szatkowski

  • 1Institut für Pharmakologie, Universitätsklinikum Essen, Hufelandstrasse 55, D-45122 Essen, Germany. martina.schmidt@uni-essen.de

Molecular and Cellular Biology
|May 15, 2004
PubMed

Insights

Epidermal growth factor receptor (EGFR) activates phospholipase C-epsilon (PLC-epsilon) through a pathway involving Rap2B GTPase and RasGRP3. This cascade regulates calcium signaling downstream of EGFR.

Area of Science:

  • Cellular signaling pathways
  • Receptor tyrosine kinase (RTK) biology
  • GTPase-mediated signal transduction

Background:

  • Phospholipase C-epsilon (PLC-epsilon) is regulated by Ras-like and Rho GTPases.
  • Epidermal growth factor (EGF) receptors (EGFRs) are receptor tyrosine kinases crucial for cell growth and differentiation.
  • Understanding the interplay between EGFR, GTPases, and PLC isoforms is key to deciphering cellular responses.

Purpose of the Study:

  • To investigate the mechanism by which EGFR regulates PLC-epsilon activity.
  • To elucidate the role of specific GTPases and guanine nucleotide exchange factors in EGFR-mediated signaling.
  • To map the signaling cascade leading to PLC-epsilon activation by EGF.

Main Methods:

  • Utilized HEK-293 cells endogenously expressing EGFR.
  • Employed clostridial toxins to inactivate Ras-related GTPases.
  • Expressed dominant-negative Rap2B and RasGRP3 to modulate signaling.
  • Assessed GTP loading, protein binding, and cellular translocation via biochemical assays.
  • Investigated the role of c-Src kinase in the pathway.

Main Results:

  • EGF activated both PLC-gamma1 and PLC-epsilon.
  • Rap2B GTP loading, binding to PLC-epsilon, and plasma membrane translocation were induced by EGF.
  • Rap2B activation was dependent on intracellular calcium and PLC-gamma1 activity.
  • RasGRP3, but not other exchange factors, enhanced Rap2B activation and downstream signaling.
  • EGF-induced tyrosine phosphorylation of RasGRP3 by c-Src was essential for Rap2B activation and PLC stimulation.

Conclusions:

  • EGFR signaling activates Rap2B via PLC-gamma1 and c-Src-mediated RasGRP3 phosphorylation.
  • This pathway leads to the activation and plasma membrane recruitment of PLC-epsilon.
  • The study reveals a novel signaling cascade regulating PLC-epsilon activity downstream of EGFR.

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