Calcium coding mechanisms in plant cell growth and immunity

钙（Ca）是所有真核生物中的第二信使。Ca信号传导的缺陷导致许多人类疾病 包括阿尔茨海默病、心力衰竭、代谢性疾病、免疫紊乱、神经退行性疾病 疾病和癌症。尽管Ca信号传导机制具有重要性和广泛的医学意义， 不清楚具有挑战性的问题涉及Ca如何编码来自不同初级 并将其转化为不同的细胞反应。编码和解码Ca信号的特异性 是信号转导领域的一个长期难题。PI的实验室研究Ca编码， 解码机制，并在解剖Ca- 编码机制，为这个应用程序搭建舞台。拟议的研究旨在了解Ca编码 在花粉管生长和先天免疫的背景下，这两种机制都涉及环核苷酸- 门控通道（CNGC）。具体目标1将解决基于CNGC的 花粉管生长过程中钙振荡与肽信号。PI的实验室鉴定了两种CNGC型蛋白质， 钙调素（CaM）在花粉管生长中形成Ca“振荡器”，也需要自分泌肽激素 由花粉管产生。最重要的假设是，肽结合到它们的受体，反过来调节 Ca振荡器通道。这将通过遗传分析结合单细胞Ca成像进行测试。的 特异性目标2将鉴定在免疫信号传导中与CNGC一起工作的Ca转运蛋白。的重要性 长期以来，Ca信号传导在动物和植物细胞的先天免疫中被认识到。私家侦探的实验室鉴定出 CNGC型通道，响应细菌病原体产生细胞质Ca峰。利用遗传 在拟南芥和酵母遗传互补模型分析中，Aim 2将鉴定转运蛋白 负责去除Ca信号，并研究它们如何与CNGC型通道协调， 塑造Ca代码的空间和时间动态。具体目标3旨在了解 植物CNGC的激活和失活。CNGC型通道在花粉管和免疫中都起作用 模型，但它们由不同的亚基组成，CaM对它们的调节也不同。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。假设植物CNGC的调节方式与 动物对应物和基于CaM的调节取决于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学方法在花粉管和免疫方面进行测试 模型拟南芥是解决基本Ca信号传导机制的理想模型，因为它提供了大量的 遗传工具和遗传突变体中的一系列全生物体和单细胞Ca信号传导表型。 这些目标的完成将揭示新的Ca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.