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Identification of Kinase-substrate Pairs Using High Throughput Screening
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Published on: August 29, 2015

Protein kinase A intersects SRC signaling in membrane microdomains

Hilde Abrahamsen1, Torkel Vang, Kjetil Taskén

  • 1Department of Medical Biochemistry, Institute of Basic Medical Sciences, University of Oslo, Box 1112, Blindern, N-0317 Oslo, Norway.

The Journal of Biological Chemistry
|February 28, 2003
PubMed

Insights

A novel pathway involving prostaglandin E2, cAMP, and protein kinase A (PKA) activates C-terminal Src kinase (Csk) to inhibit Src activity. This mechanism, operating in membrane microdomains, impacts Src substrates like Cbl and focal adhesion kinase.

Area of Science:

  • Cellular signaling
  • Molecular biology
  • Signal transduction

Background:

  • Src kinase activity is regulated by C-terminal tyrosine phosphorylation, primarily at Tyr527 by C-terminal Src kinase (Csk).
  • Dysregulation of Src signaling is implicated in various cellular processes and diseases.

Purpose of the Study:

  • To elucidate a novel signaling pathway that inhibits Src kinase activity.
  • To investigate the role of prostaglandin E2 (PGE2)-cAMP-protein kinase A (PKA) pathway in regulating Csk and Src.

Main Methods:

  • Biochemical assays to measure kinase activity (Csk and Src).
  • Cellular fractionation and analysis of detergent-resistant membrane fractions.
  • Immunoblotting to detect phosphorylation of Src and its substrates (Cbl, focal adhesion kinase).
  • Pharmacological manipulation of signaling pathways (cAMP-elevating agents, PKA activators).

Main Results:

  • Activation of the PGE2-cAMP-PKA pathway leads to Csk activation and subsequent inhibition of Src activity.
  • This inhibitory mechanism is localized to detergent-resistant membrane fractions, requiring membrane-anchored Csk.
  • Epidermal growth factor (EGF)-induced Src activation and substrate phosphorylation are suppressed by the cAMP-PKA-Csk pathway.

Conclusions:

  • A novel inhibitory mechanism for Src signaling is identified, mediated by G protein-coupled receptor activation of Csk via the cAMP-PKA pathway.
  • This pathway operates within specific membrane microdomains, highlighting the importance of spatial regulation in signal transduction.
  • The findings provide new insights into the crosstalk between G protein-coupled receptor signaling and non-receptor tyrosine kinase regulation.

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