PUBLICATION

PTPase regulation of Fyn kinase at fertilization in the zebrafish egg

Authors
Kinsey, W.H. and Wu, W.J.
ID
ZDB-PUB-021017-73
Date
2002
Source
Biology of reproduction   (Suppl. 1) 66: M30 (Abstract)
Registered Authors
Kinsey, William H., Wu, Wen-Jun
Keywords
fertilization, zebrafish egg, Fyn
MeSH Terms
none
PubMed
none
Abstract
Fertilization involves the activation of Src-family protein kinases which play a role at multiple stages of the egg activation process. The objective of the present study was to determine the mechanism by which one of these kinases, the Fyn kinase, is activated following fertilization of the zebrafish egg. Treatment of unfertilized eggs with PTPase inhibitors such as pervanadate, phenylarsine oxide, and calpeptin prevented Fyn activation in response to fertilization, suggesting that Fyn is held inactive prior to fertilization by phosphorylation of its C-terminal regulatory site. Phosphotyrosyl phosphatase inhibitors also prevented normal execution of the cortical reaction, cytoplasmic streaming, and mitosis demonstrating that PTPase activity is required for successful egg activation. In order to identify PTPases which might regulate Fyn in the egg, co-immunoprecipitation studies were performed in which Fyn immunoprecipitates were tested for PTPase activity in an in vitro phosphatase assay. The results demonstrated that a phosphotyrosyl phosphatase was tightly associated with Fyn kinase raising the possibility that a signal transduction complex consisting of Fyn and the PTPase that regulates it exists in the egg. GST fusion proteins encoding different regions of Fyn sequence were used to map the interaction to the SH2 domain of Fyn. Co-immunoprecipitation studies identified rPTPa in Fyn immunoprecipitates suggesting that rPTPa is part of the regulatory mechanism responsible for controlling Fyn activity in the egg.
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