Mechanism and function of a novel actin nucleator

描述（由申请人提供）：我们最近表明果蝇spire基因的产物p150-Spir（Spir）通过独特的机制使肌动蛋白丝形成成核（Quinlan等人，2005年）。我们最近发现，Spir直接结合到另一类肌动蛋白成核剂的成员，卡布奇诺家族formins（初步结果）。这一结果与先前的遗传研究一致，表明这两种蛋白质在相同的途径中起作用以指定发育胚胎的前后轴和背腹轴（曼索and Schupach，1989），并且定位研究表明它们在胚胎和成年哺乳动物组织中具有相同的表达模式（Schumacher et al.，2004年）。Spir和Cappuccino家族蛋白在从果蝇到人类的后生动物物种中以及在哺乳动物中是保守的，并且已知表达Spir家族蛋白的每种生物体也表达Cappuccino家族蛋白。尽管它们的保护和发展的重要性，然而，Spir和Capu的功能和调节还没有得到很好的理解。我们的研究结果表明，Spir和Cappuccino的活动是直接耦合的，它们可能在体内作为一个单一的致敏形成复合物一起发挥作用。我们的长期目标是了解这些肌动蛋白成核因子如何共同作用，以确定卵母细胞和胚胎的极性。我们的短期目标是了解Spir和Capu的活动。我们还将研究这两种蛋白质可能在体内靶向的潜在机制。具体来说，我们将：1。用Spir确定肌动蛋白成核的机制。2.描述卡布奇诺与肌动蛋白的相互作用。3.描述Spir和Cappuccino之间的相互作用。4.表征Spir FYVE结构域与脂质的相互作用。

DESCRIPTION (provided by applicant): We recently showed that the product of the Drosophila spire gene, p150-Spir (Spir) nucleates actin filament formation by a unique mechanism (Quinlan et al., 2005). We recently discovered that Spir binds directly to members of another class of actin nucleators, the Cappuccino-family formins (Preliminary Results). This result is consistent with previous genetic studies indicating that the two proteins operate in the same pathway to specify both anterior-posterior and dorsal-ventral axes of developing embryos (Manseau and Schupach, 1989) and localization studies demonstrating that they have identical expression patterns in embryonic and adult mammalian tissues (Schumacher et al., 2004). Spir- and Cappuccino-family proteins are conserved across metazoan species from fruitflies to humans and in mammals and every organism known to express a Spir-family protein also expresses a Cappuccino-family formin. Despite their conservation and their importance in development, however, the function and regulation of Spir and Capu are not well understood. Our results suggest that the activities of Spir and Cappuccino are directly coupled and that they may function together in vivo as a single filament-forming complex. Our long-term goal is to understand how these actin nucleation factors work together to determine polarity of oocytes and embryos. Our short-term goals are to understand the activities of Spir and Capu alone and in complex. We will also investigate a potential mechanism by which the two proteins may be targeted in vivo. Specifically, we will: 1. Determine the mechanism of actin nucleation by Spir. 2. Characterize the interaction of Cappuccino with actin. 3. Characterize the interaction between Spir and Cappuccino. 4. Characterize the interaction of the Spir FYVE domain with lipids.