Signaling to Cellular Intercalation in Arabidopsis

拟南芥中细胞嵌入的信号转导

• 批准号: 8333384
• 负责人: Zhenbiao Yang
• 金额: $ 29.27万
• 依托单位: UNIVERSITY OF CALIFORNIA RIVERSIDE
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8333384
• 关键词: Actins; Active Sites; Animals; Appearance; Arabidopsis; Auxins; Award; Biological Assay; Biological Models; Cell Polarity; Cell Wall; Cell surface; Cells; Clathrin; Cytokinins; Cytoskeleton; Development; Embryonic Development; Endocytosis; Epidermis; Event; Exhibits; Failure; Feedback; Gene Targeting; Generations; Genes; Genetic Transcription; Goals; Growth; Guanosine Triphosphate Phosphohydrolases; Health; Hereditary Disease; Hormones; Human; Image; In Vitro; Intercalated Cell; Investigation; Knowledge; Link; Lobe; Mediating; Microtubules; Modeling; Morphogenesis; Neural Tube Defects; Nuclear; Organ; Organism; Pathway interactions; Pattern; Pattern Formation; Phosphotransferases; Plant Leaves; Plant Model; Plants; Pregnancy; Process; Protein Kinase; Recycling; Reporter; Research; Role; Side; Signal Pathway; Signal Transduction; Site; Surface; System; Testing; WNT Signaling Pathway; Work; auxin-binding protein 1; base; cell growth; design; developmental disease; in vivo; insight; intercalation; interest; mathematical model; mutant; novel; receptor; response; rho; rho GTP-Binding Proteins; sensor; small molecule; time use; trafficking

DESCRIPTION (provided by applicant): The long-term goal of this project is to elucidate how cell polarity and morphogenesis is coordinated locally (between adjacent cells) and globally (in a field of cells) along the organ surface, because this knowledge is sorely needed to understand mechanisms of development and pattern formation. This project focuses the mechanisms underlying cellular intercalation, a fundamental process critical for human and animal embryogenesis and plant morphogenesis. Mechanisms for the local and global coordination of cellular intercalation are poorly characterized, although some underlying signaling events (e.g., Rho GTPases and the cytoskeleton) are conserved across animal and plant kingdoms. In the model plant Arabidopsis, cell intercalation is important for the development of the leaf epidermis, in which pavement cells (PC) develop interdigitated lobes and indentations to form the puzzle-piece appearance. The PI's group has established PC as a model system for cell intercalation and has discovered an elaborate Rho GTPase signaling network underpinning the PC intercalation, which involves two interplaying but mutually exclusive Rho signaling pathways: The ROP2-RIC4-actin pathway activating lobe formation and the ROP6-RIC1-microtubule pathway promoting indentation. The two pathways are complementarily localized at the opposing sides of the cell wall, but are both activated by a small molecule hormone known as auxin via the cell-surface ABP1 receptor; and the ROP2 pathway forms a positive feedback loop by activating the polarization of PIN1, which exports auxin to the cell wall. This auxin-modulated network is proposed to locally coordinate PC intercalation and to be linked to the global coordination mediated by leaf tip- and margin-high auxin gradients, which are apparently generated by a different transcription-based auxin-signaling pathway dependent on the nuclear TIR1/AFB auxin receptor. The objective of this proposal is to test the hypothesis that PC intercalation is coordinated by hierarchical auxin signaling, which may be mirrored by WNT signaling that modulates developmental patterns in animals. Aim 1 focuses detailed mechanisms by which auxin locally coordinates PC intercalation, including putative ABP1 co-receptors that are transmembrane receptor-like kinases, their differential activation of the two Rho pathways, PIN1-mediated local extracellular auxin, and its coordination of these pathways. Aim 2 will elucidate the mechanisms by which ROP2 activates PIN1 polarization via endosomal PIN1 trafficking. Aim 3 will determine roles of the TIR1/AFB pathway and its target genes in the global coordination. The work will provide a comprehensive view of the mechanisms coordinating cellular intercalation at multiple levels. Given the conserved Rho signaling underlying cell intercalation and planar cell polarity (PCP) across plants and humans, the proposed work may provide new insights into convergent extension (CE) and other PCP- mediated processes. Because failure in CE causes neural tube defects, a common developmental disorder (1 out of 1000 pregnancies), this research might ultimately be relevant to human health improvements.

描述（由申请人提供）：该项目的长期目标是阐明细胞极性和形态发生如何在器官表面局部（相邻细胞之间）和全局（细胞区域内）协调，因为这种知识非常有限。需要了解发展机制和模式形成。该项目重点关注细胞嵌入的机制，这是对人类和动物胚胎发生和植物形态发生至关重要的基本过程。尽管一些潜在的信号事件（例如 Rho GTP 酶和细胞骨架）在动物和植物界中是保守的，但细胞嵌入的局部和全局协调机制尚不清楚。在模型植物拟南芥中，细胞嵌入对于叶表皮的发育非常重要，其中铺装细胞（PC）发育出叉指状的裂片和凹痕以形成拼图的外观。 PI 小组已将 PC 建立为细胞嵌入的模型系统，并发现了支撑 PC 嵌入的复杂 Rho GTPase 信号网络，其中涉及两条相互作用但相互排斥的 Rho 信号通路：激活叶形成的 ROP2-RIC4-肌动蛋白通路和ROP6-RIC1-微管通路促进压痕。这两条途径互补地位于细胞壁的相对两侧，但均通过细胞表面 ABP1 受体被称为生长素的小分子激素激活。 ROP2途径通过激活PIN1的极化形成正反馈回路，将生长素输出到细胞壁。这种生长素调节网络被提议局部协调 PC 嵌入，并与叶尖和边缘高生长素梯度介导的全局协调联系起来，这显然是由依赖于细胞核的不同基于转录的生长素信号通路产生的。 TIR1/AFB 生长素受体。该提案的目的是检验 PC 嵌入是通过分层生长素信号传导来协调的假设，这可能通过调节动物发育模式的 WNT 信号传导来反映。目标 1 重点关注生长素局部协调 PC 嵌入的详细机制，包括假定的跨膜受体样激酶 ABP1 共受体、它们对两条 Rho 途径的差异激活、PIN1 介导的局部细胞外生长素及其对这些途径的协调。目标 2 将阐明 ROP2 通过内体 PIN1 运输激活 PIN1 极化的机制。目标 3 将确定 TIR1/AFB 通路及其靶基因在全局协调中的作用。这项工作将为在多个层面上协调细胞嵌入的机制提供全面的视角。鉴于植物和人类细胞嵌入和平面细胞极性 (PCP) 背后的保守 Rho 信号传导，拟议的工作可能为会聚延伸 (CE) 和其他 PCP 介导的过程提供新的见解。由于 CE 失败会导致神经管缺陷，这是一种常见的发育障碍（千分之一的妊娠），因此这项研究最终可能与人类健康的改善相关。