Regulation of mouse egg activation: presence of ryanodine receptors and effects of microinjected ryanodine and cyclic ADP ribose on uninseminated and inseminated eggs
Open Access
- 1 July 1995
- journal article
- Published by The Company of Biologists in Development
- Vol. 121 (7), 2233-2244
- https://doi.org/10.1242/dev.121.7.2233
Abstract
Sperm-induced activation of mammalian eggs is associated with a transient increase in Ca2+ concentrations thought to be derived from inositol 1,4,5-trisphosphate-sensitive and -insensitive intracellular stores. Whereas the importance of inositol 1,4,5-trisphosphate-sensitive Ca2+ stores has been evaluated, the identity and role of inositol 1,4,5-trisphosphate-insensitive stores are poorly understood. To explore the role of the ryanodine-sensitive Ca2+ store, we first used reverse transcription-polymerase chain reaction to identify transcripts of the ryanodine receptor in eggs and determined that transcripts for the type 2 and 3 receptor were present. Immunoprecipitation of radioiodinated egg extracts with an antibody that recognizes both type 2 and 3 receptors detected specifically a band of Mr = 520,000. Immunolocalization of the receptor(s) using laser-scanning confocal microscopy revealed that the receptor(s) was uniformly distributed in the cortex of the germinal vesicle-intact oocyte, but became asymmetrically localized to the cortex in a region apposed to the meiotic spindle in the metaphase II-arrested egg; this asymmetrical localization developed by metaphase I. The role of the ryanodine receptor in mouse egg activation was examined by determining the effects of microinjected ryanodine or cyclic ADP ribose on endpoints of egg activation in either uninseminated or inseminated eggs. Ryanodine induced the conversion of the zona pellucida glycoprotein ZP2 to its postfertilization form ZP2f in a biphasic concentration-dependent manner; nanomolar concentrations stimulated this conversion, whereas micromolar concentrations had no stimulatory effect. Cyclic ADP ribose also promoted the ZP2 conversion, but with a hyperbolic concentration dependence. Neither of these compounds induced cell cycle resumption. Inhibiting the inositol 1,4,5-trisphosphate-sensitive Ca2+ store did not inhibit the ryanodine-induced ZP2 conversion and, reciprocally, inhibiting the ryanodine-sensitive Ca2+ store did not inhibit the inositol 1,4,5-trisphosphate-induced ZP2 conversion. Last, treatment of eggs under conditions that would block the release of Ca2+ from the ryanodine-sensitive store had no effect on any event of egg activation following fertilization. Results of these experiments suggest that although ryanodine receptors are present and functional, release of Ca2+ from this store is not essential for sperm-induced egg activation.Keywords
This publication has 54 references indexed in Scilit:
- Role of G proteins in mouse egg activation: Stimulatory effects of acetylcholine on the ZP2 to ZP2f conversion and pronuclear formation in eggs expressing a functional m1 muscarinic receptorDevelopmental Biology, 1992
- Repetitive calcium transients and the role of calcium in exocytosis and cell cycle activation in the mouse eggDevelopmental Biology, 1992
- Precocious loss of cortical granules during mouse oocyte meiotic maturation and correlation with an egg-induced modification of the zona pellucidaDevelopmental Biology, 1990
- Egg-induced modifications of the zona pellucida of mouse eggs: Effects of microinjected inositol 1,4,5-trisphosphateDevelopmental Biology, 1989
- Quantitative studies of changes in cortical granule number and distribution in the mouse oocyte during meiotic maturationDevelopmental Biology, 1988
- Effects of a phorbol ester on mouse eggs: Dissociation of sperm receptor activity from acrosome reaction-inducing activity of the mouse zona pellucida protein, ZP3Developmental Biology, 1987
- Temporal and spatial dynamics of the periodic increase in intracellular free calcium at fertilization of golden hamster eggsDevelopmental Biology, 1986
- Temporal sequence and spatial distribution of early events of fertilization in single sea urchin eggs.The Journal of cell biology, 1984
- Mammalian sperm-egg interaction: Fertilization of mouse eggs triggers modification of the major zona pellucida glycoprotein, ZP2Developmental Biology, 1981
- Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4Nature, 1970