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Extracellular signal-regulated kinase activation involved in human sperm-zona pellucida binding

S S du Plessis1, C Page, D R Franken

  • 1Department of Medical Physiology and Biochemistry, University of Stellenbosch, Tygerberg, South Africa. ssdp@maties.sun.ac.za

Andrologia
|May 9, 2002
PubMed

Insights

The MEK inhibitor PD098059 enhanced sperm binding to the zona pellucida (ZP). This suggests the extracellular signal-regulated kinase (ERK) pathway is crucial for ZP-induced acrosome reactions, vital for fertilization.

Area of Science:

  • Reproductive Biology
  • Cell Signaling
  • Sperm Function

Background:

  • The acrosome reaction is essential for sperm to penetrate the egg's zona pellucida (ZP).
  • Mitogen-activated protein kinase (MAPK) pathways, particularly extracellular signal-regulated kinase (ERK), are implicated in cellular signaling.
  • Previous studies indicated a specific MAPK kinase (MEK) inhibitor, PD098059, affects the ZP-induced acrosome reaction.

Purpose of the Study:

  • To investigate the role of the ERK pathway in sperm zona binding.
  • To determine if PD098059 treatment affects sperm's ability to bind to the ZP.
  • To elucidate the physiological relevance of ZP-induced acrosome reactions.

Main Methods:

  • Sperm were treated with PD098059, a MEK inhibitor.
  • Treated and control sperm were exposed to solubilized human ZP or calcium ionophore (A23187).
  • Zona binding potential was assessed by quantifying sperm bound to the ZP.

Main Results:

  • PD098059-treated sperm showed significantly enhanced binding to solubilized ZP compared to controls.
  • No significant difference in ZP binding was observed between treated and untreated sperm after A23187 exposure.
  • These findings highlight the ERK pathway's specific involvement in ZP-mediated sperm-egg interaction.

Conclusions:

  • The extracellular signal-regulated kinase (ERK) pathway, inhibited by PD098059, plays a critical role in the zona pellucida-induced acrosome reaction.
  • ZP-induced acrosome reaction, mediated by ERK signaling, is the physiologically relevant event for successful fertilization.
  • This study supports the hypothesis that ERK-mediated signal transduction is essential for ZP-induced sperm exocytosis.

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