SPIKE1: Novel Mechanisms of ROP Activation and Actin-Based Morphogenesis

摘要细胞是构成复杂组织和器官的基本单位。了解细胞如何动态地改变它们的形状来执行它们的特殊功能是生物学中的一个重要问题。小GTP酶的ROP家族在控制植物细胞形状的信号转导途径中起作用。 ROP信号传导的主要靶点是细胞骨架，即丝状蛋白的三维阵列，包括支配生长的空间和时间模式的肌动蛋白。从ROP活化到细胞骨架重排，很难描述一条通路中的所有元件。在这个项目中，SPIKE 1突变体（spk 1）被用作起点，以了解细胞形状控制植物使用遗传和生物化学方法。 具体地说，实验将检查ROP介导的途径中的突变对毛状体的影响，毛状体是通常称为毛发的单细胞叶结构。 SPIKE 1（SPK 1）被认为是一种鸟嘌呤核苷酸交换因子（GEF），对ROP GTP酶起正性调节作用。 Szymanski博士的研究将确定1）SPK 1的细胞位置，2）SPK 1如何调节ROP和3）将SPK 1信号传导与直接控制肌动蛋白细胞骨架的蛋白质联系起来Szymanski博士的小组将使用一组称为扭曲的表皮毛发突变体来测试SPK 1是否调节称为肌动蛋白相关蛋白（阿普）的蛋白质复合物2/3，在细胞中产生肌动蛋白丝的网络。这项工作将提供深入了解多细胞生物如何接收和传输控制极化生长和组织发育的信号。该项目将涉及本科生，研究生和博士后研究员的多元化群体。参加普渡大学MARC-AIM暑期研究体验项目的少数民族学生也将有机会参加这个研究项目。 在这个项目中使用的研究材料也与本科遗传学实验室课程相结合。

ABSTRACTCells are the building blocks of complex tissues and organs. Understanding how cells dynamically change their shape to carry out their specialized functions is an important question in biology. The ROP family of small GTPases acts in the signal transduction pathways that control cell shape in plants. A major target of ROP signaling is the cytoskeleton, a three dimensional array of filamentous proteins, including actin that dictate the spatial and temporal patterns of growth. It has been difficult to characterize all of the elements in a pathway, from ROP activation to rearrangement of the cytoskeleton. In this project the SPIKE1 mutant (spk1) is used as the starting point to understand cell shape control in plants using genetic and biochemical approaches. Specifically the experiments will examine the effect of mutations in the ROP-mediated pathway on trichomes, single celled leaf structures commonly called hair. SPIKE1 (SPK1) is proposed to act as a guanine nucleotide exchange factor (GEF) that positively regulate ROP GTPases. Dr. Szymanski's research will determine 1) the cellular location of SPK1, 2) how SPK1 regulates ROP and 3) will link SPK1 signaling to proteins that directly control the actin cytoskeleton Dr. Szymanski's group will use a collection of epidermal hair mutants called distorted to test whether SPK1 regulates a protein complex called the Actin-related protein (Arp) 2/3 that generates the networks of actin filaments in the cell. This work will provide insight into how multicellular organisms receive and transmit signals that control polarized growth and tissue development. The project will involve a diverse group of undergraduate, graduate, and post-doctoral fellows. Minority students that participate in the MARC-AIM summer research experience program at Purdue will also have an opportunity to participate in this research project. The research materials used in this project are also integrated with an undergraduate genetics laboratory course.