Involvement of Phospholipase Cgamma 1 in Mouse Egg Activation Induced by a Truncated Form of the C-kit Tyrosine Kinase Present in Spermatozoa
Sette ; C. ; - ASI Sponsor
Aug - 1998
ISSN : 00219525 ;
journal : The Journal of Cell Biology

Issue : 4
type: Article Journal

Abstract
Microinjection of a truncated form of the c-kit tyrosine kinase present in mouse spermatozoa (tr-kit) activates mouse eggs parthenogenetically, and tr-kit- induced egg activation is inhibited by preincubation with an inhibitor of phospholipase C (PLC) (Sette, C., A. Bevilacqua, A. Bianchini, F. Mangia, R. Geremia, and P. Rossi. 1997. Development [Camb.]. 124:2267-2274). Co-injection of glutathione-S-transferase (GST) fusion proteins containing the src-homology (SH) domains of the \gamma\1 isoform of PLC (PLC\gamma\1) competitively inhibits tr-kit- induced egg activation. A GST fusion protein containing the SH3 domain of PLC\gamma\1 inhibits egg activation as efficiently as the whole SH region, while a GST fusion protein containing the two SH2 domains is much less effective. A GST fusion protein containing the SH3 domain of the Grb2 adaptor protein does not inhibit tr-kit-induced egg activation, showing that the effect of the SH3 domain of PLC\gamma\1 is specific. Tr-kit-induced egg activation is also suppressed by co-injection of antibodies raised against the PLC\gamma\1 SH domains, but not against the PLC\gamma\1 COOH-terminal region. In transfected COS cells, coexpression of PLC\gamma\1 and tr-kit increases diacylglycerol and inositol phosphate production, and the phosphotyrosine content of PLC\gamma\1 with respect to cells expressing PLC\gamma\1 alone. These data indicate that tr-kit activates PLC\gamma\1, and that the SH3 domain of PLC\gamma\1 is essential for tr-kit-induced egg activation.

keywords :