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Localized activation of Src-family protein kinases in the mouse egg Lynda K. McGinnis, David F. Albertini, William H. Kinsey
 

Summary: Localized activation of Src-family protein kinases in the mouse egg
Lynda K. McGinnis, David F. Albertini, William H. Kinsey
Department of Anatomy and Cell Biology, Center for Reproductive Sciences, University of Kansas Medical Center,
3901 Rainbow Blvd., Kansas City, KS 66160, USA
Received for publication 15 November 2006; revised 15 March 2007; accepted 16 March 2007
Available online 24 March 2007
Abstract
Recent studies in species that fertilize externally have demonstrated that fertilization triggers localized activation of Src-family protein kinases
in the egg cortex. However, the requirement for Src-family kinases in activation of the mammalian egg is different from lower species and the
objective of this study was to characterize changes in the distribution and activity of Src-family protein tyrosine kinases (PTKs) during zygotic
development in the mouse. Immunofluorescence analysis of mouse oocytes and zygotes with an anti-phosphotyrosine antibody revealed that
fertilization stimulated accumulation of P-Tyr-containing proteins in the egg cortex and that their abundance was elevated in the region overlying
the MII spindle. In addition, the poles of the MII spindle exhibited elevated P-Tyr levels. As polar body extrusion progressed, P-Tyr-containing
proteins were especially concentrated in the region of cortex adjacent to the maternal chromatin and the forming polar body. In contrast, P-Tyr
labeling of the spindle poles eventually disappeared as meiosis II progressed to anaphase II. In approximately 24% of cases, the fertilizing sperm
nucleus was associated with increased P-Tyr labeling in the overlying cortex and oolemma.
To determine whether Src-family protein tyrosine kinases could be responsible for the observed changes in the distribution of P-Tyr containing
proteins, an antibody to the activated form of Src-family PTKs was used to localize activated Src, Fyn or Yes. Activated Src-family kinases were
found to be strongly associated with the meiotic spindle at all stages of meiosis II; however, no concentration of labeling was evident at the egg
cortex. The absence of cortical Src-family PTK activity continued until the blastocyst stage when strong cortical activity became evident. At the

  

Source: Albertini, David - Center for Reproductive Sciences, University of Kansas

 

Collections: Biology and Medicine