Fyn kinase–tubulin interaction during meiosis of rat eggs

Abstract

Prior to fertilization, the spindle of vertebrate eggs must remain stable and well organized during the second meiotic metaphase arrest (MII). In a previous study we have determined that the completion of meiosis is a Src family kinase (SFK)-dependent event. In the current study we have used the SFK inhibitors, SU6656 and PP2, and demonstrated that inhibition of SFKs caused the formation of a disorganized spindle. The observation that proper organization of an MII spindle is an SFK-dependent process, combined with our previous finding that Fyn kinase is localized at the microtubules (MTs), prompted us to examine the potential role of Fyn in MT signaling. Our results show an association between Fyn and tubulin, the ability of Fyn to phosphorylate tubulin in vitro and stimulation of meiosis completion by injection of a constitutively active form of Fyn (CAF). We suggested that SFKs mediate significant functions during the organization of the MII spindle. In view of CAF injection experiments, and of the pronounced concentration of Fyn kinase at the spindle, we propose that Fyn may play an important role in some aspects of the spindle functions, possibly those involving the MTs.

Role of Src homology 2 domain-mediated PTK signaling in mouse zygotic development

“…The extent to which these pathways are active in mammalian fertilization is now the subject of much investigation. Analysis of mammalian egg activation using chemical inhibitors (PP2 and SU6656), which are reasonably specific for Src-family PTKs (Bain et al 2003) has demonstrated that MII resumption induced parthenogenetically by calcium ionophore or by Tr-kit required Src-family PTK activity (Sette et al 2002, Talmor-Cohen et al 2004b. Once meiosis was completed, suppression of PTKs in the mouse zygote by genistein caused a second block in which DNA synthesis was suppressed and the zygotes failed to exit S-phase of the cell cycle (Besterman & Schultz 1990).…”

“…In addition, microinjection of active Fyn kinase has been shown to stimulate meiosis resumption in mouse and rat (Sette et al 2002, Talmor-Cohen et al 2004b. A second requirement for Src-family PTK activity at S-or S/G2-phase of the first mitotic division has been demonstrated using chemical inhibitors, such as genistein (Besterman & Schultz 1990, Jacquet et al 1995.…”

Phospho-Signaling at Oocyte Maturation and Fertilization: Set Up for Embryogenesis and Beyond Part I. Protein Kinases

“…Further, knockdown of FYN kinase by siRNA resulted in an approximately 50% reduction in progression to metaphase II similar to what was observed in oocytes isolated from Fyn-knockout mice matured in vitro. These results clearly demonstrate that involvement of Fyn in oocyte and egg functions vary among species Kierszenbaum et al 2009;Kinsey 1995;Kinsey 1996;Kinsey and Shen 2000;Kinsey et al 2003;Levi et al 2010;Luo et al 2009;McGinnis et al 2009 Sette et al 2002;Sharma and Kinsey 2006;Sharma and Kinsey 2008;Steele et al 1990;Talmor et al 1998;Talmor-Cohen et al 2004b;Wu and Kinsey 2000;Wu and Kinsey 2002;Wu and Kinsey 2004).…”

Phospho-Signaling at Oocyte Maturation and Fertilization: Set Up for Embryogenesis and Beyond Part II. Kinase Regulators and Substrates

“…Vg1 RBP is associated with microtubules and co-precipitated by heterologous, polymerized tubulin in Xenopus oocytes (Elisha et al 1995). It was shown recently that Fyn and tubulin are closely associated where Fyn can phosphorylate tubulin and thus SFKs mediate significant functions during the organization of the MII spindle that involves possibly microtubules in rat eggs (Talmor-Cohen et al 2004). Similarly, well-organized microtubule formation increased the GVBD and MII development in mouse oocytes (Mohammadi Roushandeh and Habibi Roudkenar 2009).…”