An adhesion-associated agonist from the zona pellucida activates G protein-promoted elevations of internal Ca2+ and pH that mediate mammalian sperm acrosomal exocytosis

Dev Biol. 1989 Sep;135(1):133-46. doi: 10.1016/0012-1606(89)90164-4.

Abstract

Solubilized oocyte zonae pellucidae promoted acrosomal exocytosis in fura-2- or carboxyfluorescein-loaded, mature bovine sperm. Associated elevations of internal [Ca2+] and pH in sperm suspensions were first detectable at 2-5 min, without apparent temporal resolution, and increased monotonically thereafter. Video imaging of fura-2-loaded, single cells identified a responsive subpopulation, destined to undergo exocytosis, that displayed no early transient but manifested lags of 1-7 min then sustained elevations of internal [Ca2+]. Both the zona-induced exocytosis and dye responses were diminished for functionally immature sperm and for mature sperm treated preliminarily with pertussis toxin. Together, these results indicate that a developmentally regulated mechanism of signal transduction employs G protein(s) to couple the physiological (zona) agonist to alterations of the internal ionic mediators of acrosomal exocytosis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acrosome / physiology*
  • Animals
  • Calcium / physiology
  • Cattle
  • Cell Adhesion*
  • Cell Compartmentation
  • Cytoplasm / physiology
  • Exocytosis / drug effects
  • GTP-Binding Proteins / physiology*
  • Hydrogen-Ion Concentration
  • Image Processing, Computer-Assisted
  • In Vitro Techniques
  • Male
  • Ovum / physiology*
  • Pertussis Toxin
  • Solubility
  • Spermatozoa / physiology*
  • Video Recording
  • Virulence Factors, Bordetella / pharmacology
  • Zona Pellucida / physiology*

Substances

  • Virulence Factors, Bordetella
  • Pertussis Toxin
  • GTP-Binding Proteins
  • Calcium