A rho scaffold integrates the secretory system with feedback mechanisms in regulation of auxin distribution.
A rho scaffold integrates the secretory system with feedback mechanisms in regulation of auxin distribution.
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DOI：
10.1371/journal.pbio.1000282
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发表时间：
2010-01-19
期刊：
影响因子：
9.8
通讯作者：
Yalovsky S
中科院分区：
文献类型：
--
作者：
Hazak O;Bloch D;Poraty L;Sternberg H;Zhang J;Friml J;Yalovsky S
在植物中，生长素的分布和组织图案通过涉及生长素调节的细胞极性因子ICR 1和分泌机制的反馈回路来协调。多细胞生物体的发育依赖于单个细胞通过小信号分子协调其行为以形成正确图案化组织的能力。在植物中，信号分子生长素在细胞之间的定向运输的独特机制连接细胞极性和组织模式，因此是植物发育的许多方面所必需的。生长素流动的方向由PIN生长素流出转运蛋白的极性亚细胞定位决定。动态PIN极性定位的结果，从组成性的内吞循环，从质膜，但它是不是很好地理解这种机制如何连接到调节细胞极性。Rho家族小GTP酶ROP/RAC是细胞极性的主要调节者，然而它们在调节极性蛋白运输和极性生长素运输中的作用尚未确定。在这里，通过突变体和转基因植物的分析，我们表明，ROP相互作用和极性调节支架蛋白ICR 1的PIN蛋白在质膜的极性域的招聘是必需的。ICR 1突变体胚和植物显示出一系列严重的发育畸变，这些畸变是由受损的差异生长素分布引起的。ICR 1在胞吐所需的质膜上发挥作用，但不与PIN一起再循环。ICR 1的表达迅速诱导生长素，但抑制在稳定的生长素最大值的位置在垂体，后来在胚胎和成熟的根分生组织。我们的研究结果表明，ICR 1是一个生长素调节的正反馈回路的一部分，实现了一个独特的整合生长素依赖的转录调控到ROP介导的调制细胞极性。因此，ICR 1在细胞极性、胞吐作用和生长素转运依赖的组织模式之间形成生长素调节的联系。图案形成过程中不同细胞的协调是多细胞生物发育的基本过程。在植物中，生长素信号分子在细胞间定向运输的独特机制证明了细胞极性对组织图案的重要性。生长素流动的方向由称为PIN的生长素转运蛋白的极性亚细胞定位决定，PIN促进生长素流出。同时，生长素介导的正反馈机制加强了PIN的极性分布。然而，极性PIN定位的分子机制还没有很好地理解。在真核细胞中，小GTP酶的Rho家族作为细胞极性的中心调节物起作用。我们表明，Rho相互作用的蛋白质从植物，称为ICR 1，需要招聘通过分泌系统的PIN蛋白在细胞膜中的极性结构域。因此，ICR 1是生长素定向运输和分布所必需的，从而也是正确图案形成所必需的。此外，ICR 1的表达和亚细胞定位都受生长素的调节，这表明ICR 1可能在一个正反馈回路中起作用，从而加强生长素的分布。因此，ICR 1在细胞极性、蛋白质分泌和生长素依赖的组织模式之间形成生长素调节的联系。
In plants, auxin distribution and tissue patterning are coordinated via a feedback loop involving the auxin-regulated cell polarity factor ICR1 and the secretory machinery. Development in multicellular organisms depends on the ability of individual cells to coordinate their behavior by means of small signaling molecules to form correctly patterned tissues. In plants, a unique mechanism of directional transport of the signaling molecule auxin between cells connects cell polarity and tissue patterning and thus is required for many aspects of plant development. Direction of auxin flow is determined by polar subcellular localization of PIN auxin efflux transporters. Dynamic PIN polar localization results from the constitutive endocytic cycling to and from the plasma membrane, but it is not well understood how this mechanism connects to regulators of cell polarity. The Rho family small GTPases ROPs/RACs are master regulators of cell polarity, however their role in regulating polar protein trafficking and polar auxin transport has not been established. Here, by analysis of mutants and transgenic plants, we show that the ROP interactor and polarity regulator scaffold protein ICR1 is required for recruitment of PIN proteins to the polar domains at the plasma membrane. icr1 mutant embryos and plants display an a array of severe developmental aberrations that are caused by compromised differential auxin distribution. ICR1 functions at the plasma membrane where it is required for exocytosis but does not recycle together with PINs. ICR1 expression is quickly induced by auxin but is suppressed at the positions of stable auxin maxima in the hypophysis and later in the embryonic and mature root meristems. Our results imply that ICR1 is part of an auxin regulated positive feedback loop realized by a unique integration of auxin-dependent transcriptional regulation into ROP-mediated modulation of cell polarity. Thus, ICR1 forms an auxin-modulated link between cell polarity, exocytosis, and auxin transport-dependent tissue patterning. The coordination of different cells during pattern formation is a fundamental process in the development of multicellular organisms. In plants, a unique mechanism of directional transport of the signaling molecule auxin between cells demonstrates the importance of cell polarity for tissue patterning. The direction of auxin flow is determined by polar subcellular localization of auxin transport proteins called PINs, which facilitate auxin efflux. At the same time, an auxin-mediated positive feedback mechanism reinforces the polar distribution of PINs. However, the molecular mechanisms that underlie polar PIN localization are not well understood. In eukaryotic cells, the Rho family of small GTPases function as central regulators of cell polarity. We show that a Rho-interacting protein from plants, called ICR1, is required for recruitment via the secretory system of PIN proteins to polar domains in the cell membrane. As a result, ICR1 is required for directional auxin transport and distribution and thereby for proper pattern formation. In addition, both the expression and subcellular localization of ICR1 are regulated by auxin, suggesting that ICR1 could function in a positive feedback loop that reinforces auxin distribution. Thus, ICR1 forms an auxin-modulated link between cell polarity, protein secretion, and auxin-dependent tissue patterning.
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影响因子：
3.3
作者：
Bloch, D;Lavy, M;Yalovsky, S
通讯作者：
Yalovsky, S
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64.5
作者：
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影响因子：
9.2
作者：
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通讯作者：
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64.8
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Dhonukshe, Pankaj;Tanaka, Hirokazu;Goh, Tatsuaki;Ebine, Kazuo;Mahonen, Ari Pekka;Prasad, Kalika;Blilou, Ikram;Geldner, Niko;Xu, Jian;Uemura, Tomohiro;Chory, Joanne;Ueda, Takashi;Nakano, Akihiko;Scheres, Ben;Friml, Jiri
通讯作者：
Friml, Jiri