The mechanism of cell size regulation by polycystins

多囊藻毒素在细胞生长过程中的机械传感机制 胞质分裂是细胞分裂的最后阶段，当两个子细胞分离时，但它对 向细胞生长过渡，包括细胞大小扩大。管理这种转变的机制很差。 明白了。我们在研究过程中确定了钙和多囊蛋白通道Pkd2p在这一过程中的作用 模式生物分裂酵母的胞质分裂。Pkd2p是调节细胞大小所必需的，它介导了 钙离子内流。多囊蛋白是进化上保守的离子通道。人类功能突变的丧失 多囊蛋白导致遗传性疾病--常染色体多囊肾病(ADPKD)。细胞功能 对这一高度保守的渠道家族的了解还不是很清楚。这项研究将确定Pkd2p和 钙调节向细胞生长的过渡。 目的1.确定河马信号通路对Pkd2p的调节作用。我们的基因筛查已经确定了 裂解酵母河马途径SIN和MOR对Pkd2p的调节至关重要。两者都高度保守 对细胞增殖至关重要的激酶级联反应。SIN拮抗Pkd2p活性，而MOR则协同作用 使用Pkd2p。然而，其机制尚不清楚。我们将确定MOR和SIN如何调节细胞 通过钙成像观察胞质分裂过程中的钙。2)确定MOR和SIN如何调节细胞大小中的Pkd2p 扩张。3)确定MOR如何促进细胞周期依赖的Pkd2p的定位。4)确定 Pkd2p是否是MOR激酶Orb6p的直接底物。目标2.确定Pkd2p通道如何 激活了。体外实验中，PKD2通道在机械力作用下开放，但其机制尚不清楚。我们会 测试Pkd2p是一个对推动酵母细胞生长的力量敏感的通道的提议。我们将1)确定 当细胞受到外力刺激时，Pkd2p如何调节钙离子。2)探索Pkd2p的含义 渗透刺激和体外脂质环境，与Allen Liu的研究小组(University Of Liu) 密歇根州)。3)使用补丁确定Pkd2p通道是否允许钙以外的离子通过 CLAMP，通过与杜建阳的团队(田纳西大学)合作完成。目标3确定如何 Pkd2p调控胞质分裂过程中肌动蛋白的重组。钙可以激活两个高度保守的 Cam1p和Ppb1p分子。我们将确定它们如何在胞质分裂中对Pkd2p的作用做出贡献。我们会 确定1)在胞质分裂过程中，Pkd2p如何调节依赖于Cam1p的内吞作用。2)Pkd2p如何 调节依赖于Cam1p的细胞内转运。3)Pkd2p如何调节Ppb1p的酶活性。 通过这项研究，我们希望发现一条由Pkd2p通道介导的新的细胞大小调节途径。我们 将演示内部信号通路和外部环境如何在激活 胞质分裂中的这个通道。我们将采用新的成像方法与创新的体外技术相结合 在我们的书房里。我们的工作将帮助我们更好地理解人类多囊蛋白的细胞功能。

The mechanism of mechanosensing by polycystins during cell growth Cytokinesis is the last stage of cell division when two daughter cells separate, but it is equally important for the transition to cell growth including cell size expansion. The mechanism regulating such a transition is poorly understood. We identified the role of calcium and the polycystin channel Pkd2p in this process while studying cytokinesis of the model organism fission yeast. Pkd2p is essential to regulate the cell size and it mediates calcium influx. Polycystins are evolutionally conserved ion channels. Loss of function mutations of human polycystins lead to the genetic disorder, Autosomal Polycystic Kidney Disorder (ADPKD). The cellular function of this highly conserved family of channels is not well understood. This study will determine how Pkd2p and calcium regulate the transition to cell growth. Aim 1. Determine how the Hippo signaling pathways regulate Pkd2p. Our genetic screen has identified the fission yeast Hippo pathways SIN and MOR as crucial for the regulation of Pkd2p. Both are highly conserved kinase cascades that are essential for cell proliferation. SIN antagonizes Pkd2p activity, while MOR synergizes with Pkd2p. However, the mechanism is unclear. We will 1) Determine how MOR and SIN regulate cellular calcium during cytokinesis through calcium-imaging. 2) Determine how MOR and SIN regulate Pkd2p in cell size expansion. 3) Determine how MOR promotes the cell cycle-dependent localization of Pkd2p. 4) Determine whether Pkd2p is a direct substrate of the MOR kinase Orb6p. Aim 2. Determine how the Pkd2p channel is activated. Pkd2 channel opens in response to mechanical force in vitro, but the mechanism is unclear. We will test the proposal that Pkd2p is a channel sensitive to the force driving the yeast cell growth. We will 1) Determine how Pkd2p regulates calcium when the cells are stimulated by external force. 2) Probe how Pkd2p senses osmotic stimuli and the lipid environment in vitro through a collaboration with Allen Liu’s group (University of Michigan). 3) Determine whether Pkd2p channel allows ions other than calcium to pass through, using patch clamp, through a collaboration with Du Jianyang’s group (University of Tennessee). Aim 3 Determine how Pkd2p regulates the actin re-organization during cytokinesis. Calcium can activate two highly conserved molecules Cam1p and Ppb1p. We will determine how they contribute to the role of Pkd2p in cytokinesis. We will determine 1) how Pkd2p regulates the Cam1p-dependent endocytosis during cytokinesis. 2) how Pkd2p regulates the Cam1p-dependent intracellular transport. 3) how Pkd2p regulates the enzymatic activity of Ppb1p. Through this study, we expect to uncover a novel cell size regulation pathway mediated by Pkd2p channel. We will demonstrate how both internal signaling pathways and external environment play a vital role in activating this channel in cytokinesis. We will employ novel imaging methods combined with innovative in vitro techniques in our study. Our works shall help us better understand the cellular functions of the human polycystins.