Calcium coding mechanisms in plant cell growth and immunity

钙是真核生物中的第二信使。钙信号的缺陷会导致多种人类疾病 包括阿尔茨海默氏症、心力衰竭、代谢性疾病、免疫紊乱、神经退行性变 疾病和癌症。尽管钙信号的重要性和广泛的医学意义，钙信号机制仍然 不清楚。具有挑战性的问题涉及到Ca如何编码来自不同主源的特定信息 并将它们转化为不同的细胞反应。钙信号的特异性编码和译码 这一直是信号转导领域的一个难题。PI的实验室研究钙编码和 以拟南芥为模式系统的解码机制，在解剖钙离子方面取得了突破性进展。 编码机制，为这一应用程序奠定了基础。拟议的研究试图理解钙编码 花粉管生长和先天免疫的机制都涉及环核苷酸- 拟南芥的门控通道(CNGC)。具体目标1将解决基于CNGC的 花粉管生长过程中的CA振荡和多肽信号。Pi的实验室发现了两种CNGC型蛋白质和 钙调素(CaM)在花粉管生长中形成钙“振荡器”也需要自分泌多肽激素 由花粉管产生。最重要的假设是，多肽与它们的受体结合，而受体反过来调节 CA振荡器通道。这将通过结合单细胞钙成像的遗传分析进行测试。这个 特异性目标2将确定与CNGC共同作用于免疫信号的钙转运体。它的重要性 在动植物细胞的先天免疫中，钙信号转导机制早已被公认。派的实验室发现了一种 CNGC型通道，响应细菌病原体而产生细胞质钙尖峰。使用遗传 在拟南芥和酵母遗传互补模型中的分析，Aim 2将识别转运蛋白 负责去除钙信号，并研究它们如何与CNGC型通道协调，以精确 塑造钙码的空间和时间动态。具体目标3试图了解 植物CNGCs的激活和失活。CNGC型通道在花粉管和免疫中都起作用 模型，但它们由不同的亚单位组成，它们的凸轮规则也不同。此外，虽然动物 CNGCs被环核苷酸(cAMP/cGMP)、植物花粉管中的CNGCs和免疫激活 模型对这些核苷酸不敏感。假设是植物CNGCs受到不同于 动物对应体和基于CaM的调控依赖于CNGC的亚基组成。这一假设 将在目标3中使用生物化学和电生理方法在花粉管和免疫中进行测试 模特。拟南芥是解决基本钙信号机制的理想模型，因为它提供了过多的 遗传工具以及遗传突变体中的一系列全生物和单细胞钙信号表型。 这些目标的完成将揭示新的钙编码机制，有助于建立 CA信号与人类健康密切相关。

Calcium (Ca) is a second messenger in all eukaryotes. Defects in Ca signaling cause numerous human diseases including Alzheimer’s disease, heart failure, metabolic diseases, immune disorders, neurodegenerative diseases, and cancer. Despite the importance and broad medical implications, Ca signaling mechanisms remain unclear. The challenging question concerns how Ca encodes specific information coming from different primary signals and translate them into distinct cellular responses. Coding and decoding the specificity of Ca signals remains a long-standing puzzle in the signal transduction field. The PI’s laboratory studies Ca coding and decoding mechanisms using Arabidopsis as a model system and has made breakthroughs in dissecting Ca- coding mechanisms, setting the stage for this application. The proposed studies seek to understand Ca-coding mechanisms in the contexts of pollen tube growth and innate immunity both of which involve cyclic nucleotide- gated channels (CNGCs) in Arabidopsis. The Specific Aim 1 will address the relationship between CNGC-based Ca oscillations and peptide signaling during pollen tube growth. PI’s lab identified two CNGC-type proteins and calmodulin (CaM) forming a Ca “oscillator” in pollen tube growth that also requires autocrine peptide hormones produced by pollen tube. The overarching hypothesis is that peptides bind to their receptors that in turn modulate Ca-oscillator channels. This will be tested through genetic analysis combined with single cell Ca imaging. The Specific Aim 2 will identify Ca transporters that work together with CNGCs in immunity signaling. The importance of Ca signaling has long been recognized in innate immunity for both animal and plant cells. PI’s lab identified a CNGC-type channel that generates cytoplasmic Ca spike in response to bacterial pathogens. Using genetic analysis in Arabidopsis and yeast genetic complementation models, Aim 2 will identify the transporters responsible for removing the Ca signal and study how they coordinate with CNGC-type channels to precisely shape the spatial and temporal dynamics of Ca codes. Specific Aim 3 seeks to understand the mechanisms for activation and inactivation of plant CNGCs. The CNGC-type channels function in both pollen tube and immunity models, but they consist of different subunits and their regulations by CaM are different too. Further, while animal CNGCs are activated by the cyclic nucleotides (cAMP/cGMP), the plant CNGCs in pollen tube and immunity models are insensitive to these nucleotides. The hypothesis is that plant CNGCs are regulated differently from animal counterparts and CaM-based regulation depends on subunit composition of the CNGCs. This hypothesis will be tested in Aim 3 using biochemical and electrophysiological approaches in both pollen tube and immunity model. Arabidopsis is an ideal model to address basic Ca signaling mechanisms, as it provides a plethora of genetic tools and an array of whole-organism and single-cell Ca signaling phenotypes in the genetic mutants. Completion of these aims will reveal new Ca coding mechanisms, contributing to the conceptual framework of Ca signaling highly relevant to human health.