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Epidermal growth factor stimulation of the ACK1/Dbl pathway in a Cdc42 and Grb2-dependent manner

J Kato-Stankiewicz1, S Ueda, T Kataoka

  • 1Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, 226-8501, Japan.

Biochemical and Biophysical Research Communications
|June 8, 2001
PubMed

Insights

Epidermal growth factor (EGF) activates the ACK1/Dbl pathway, influencing actin cytoskeleton rearrangements. This process requires both Cdc42 and Grb2, highlighting ACK1

Area of Science:

  • Cell biology
  • Molecular signaling
  • Cytoskeletal dynamics

Background:

  • The ACK1/Dbl signaling pathway regulates Rho family GTP-binding proteins, crucial for cellular processes.
  • The precise regulatory mechanisms of ACK1/Dbl signaling in response to extracellular stimuli are not fully understood.

Purpose of the Study:

  • To elucidate the regulatory mechanism of the ACK1/Dbl pathway stimulated by epidermal growth factor (EGF).
  • To investigate the roles of ACK1-binding proteins Cdc42 and Grb2 in EGF-induced signaling.
  • To determine how ACK1 mediates EGF signals to Rho GTPases.

Main Methods:

  • Overexpression of the Cdc42/Rac interactive binding domain and a dominant-negative Grb2 mutant to assess protein interactions.
  • Analysis of tyrosine phosphorylation of ACK1 and Dbl in response to EGF.
  • Ectopic expression of ACK1 to observe effects on focal complex and stress fiber formation.
  • Treatment with botulinum toxin C to assess the role of Rho.

Main Results:

  • EGF stimulation activates the ACK1/Dbl pathway, leading to actin cytoskeletal rearrangements.
  • Inhibition of ACK1 interaction with Cdc42 or Grb2 diminished ACK1 and Dbl tyrosine phosphorylation upon EGF stimulation.
  • EGF signaling requires both Cdc42-dependent and Grb2-dependent processes for ACK1 activation.
  • Ectopic ACK1 expression induced focal complex and stress fiber formation, sensitive to botulinum toxin C, indicating a role for Rho.

Conclusions:

  • ACK1 acts as a crucial mediator of EGF signals to Rho family GTP-binding proteins.
  • ACK1 activation and downstream signaling necessitate both Cdc42-dependent and Grb2-dependent pathways.
  • The ACK1/Dbl pathway plays a significant role in EGF-induced cytoskeletal dynamics, involving Rho GTPases.

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