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Activation of Src-family PTK activity at fertilization: role of the SH2 domain

William H Kinsey1, W Wu, Elinor Macgregor

  • 1Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA. wkinsey@kumc.edu

Developmental Biology
|November 19, 2003
PubMed

Insights

Src-family kinases (SFKs) are crucial for egg activation. This study shows that GST-Fyn-SH2 fusion proteins inhibit SFK activation, preventing fertilization-induced calcium transients in zebrafish eggs.

Area of Science:

  • Cell Biology
  • Developmental Biology
  • Biochemistry

Background:

  • Src-family protein tyrosine kinases (SFKs) play a known role in egg activation.
  • GST fusion proteins with Src or Fyn SH2 domains inhibit sperm-induced calcium transients and cause polyspermy.
  • The mechanism by which these fusion proteins inhibit SFK function remains unclear.

Purpose of the Study:

  • To investigate the hypothesis that SH2 domain fusion proteins prevent SFK activation upon fertilization.
  • To elucidate the mechanism of dominant-negative inhibition by SFK SH2 domains.

Main Methods:

  • Development of a single-cell assay to measure SFK activity in eggs.
  • Injection of zebrafish eggs with GST-Fyn-SH2 fusion protein.
  • Observation of sperm-induced calcium transients.

Main Results:

  • The GST-Fyn-SH2 fusion protein successfully inhibited fertilization-induced SFK activation in zebrafish eggs.
  • This inhibition occurred at concentrations that also suppressed the sperm-induced calcium transient.
  • The study provides evidence for the mechanism of dominant-negative inhibition.

Conclusions:

  • GST-Fyn-SH2 fusion proteins act by preventing the activation of SFKs in response to fertilization.
  • This finding clarifies the role of SFKs in egg activation and fertilization.
  • The developed assay is valuable for studying SFK activity in vivo.

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