Journal of Reproductive Immunology
53 (2002) 161–169
Signaling through protein kinases during egg
activation
Efrat Eliyahu, Anat Talmor-Cohen, Ruth Shalgi *
Department of Embryology, Sackler Faculty of Medicine, Tel Ai Uniersity, Ramat -Ai 69978,
Tel -Ai, Israel
Received 9 April 2001; accepted 16 April 2001
Abstract
Following penetration of the zona pellucida, the mammalian spermatozoon binds and
fuses with the egg plasma membrane, thereby fertilizing the egg that is still arrested at the
second metaphase. Fertilization initiates in the egg a sequence of events referred to as ‘egg
activation’. An initial increase in intracellular Ca
2 +
concentration ([Ca
2 +
]
i
) appears to be
the very early cellular event observed which leads to the cortical granules exocytosis and
resumption of meiosis. Various treatments can induce parthenogenetic activation mimicking
at least part of the fertilization events. Similar to somatic cells, studies in mammalian eggs
suggest that signal transduction pathways mediate egg activation. The initial increase in
[Ca
2 +
]
i
appears to be critical for egg activation. However, other messengers such as protein
kinase C (PKC) and protein tyrosine kinases (PTKs), were suggested as possible inducers of
some aspects of egg activation. In the present work, studies concerning the involvement of
protein kinases during egg activation in our laboratory and in others are summarized.
© 2002 Elsevier Science Ireland Ltd. All rights reserved.
Keywords: Egg; Signal transduction; Activation; Mammals
www.elsevier.com/locate/jreprimm
1. Introduction
At fertilization, a spermatozoon binds to and then fuses with an egg that
is arrested at the second meiotic metaphase. Sperm egg interaction initiates
* Corresponding author. Tel.: +972-3-640-8685; fax: +972-3-640-6149.
E-mail address: shalgir@post.tau.ac.il (R. Shalgi).
0165-0378/02/$ - see front matter © 2002 Elsevier Science Ireland Ltd. All rights reserved.
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