Defining the dynamic interplay of a MAPK signaling cascade involved in plant growth, development and sexual reproduction.

定义参与植物生长、发育和有性生殖的 MAPK 信号级联的动态相互作用。

• 批准号: RGPIN-2014-03883
• 负责人: Matton, Daniel
• 金额: $ 2.91万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=610700
• 关键词: Defining; dynamic; interplay; MAPK; signaling

Communication and information transfer is everything, not only for our day-to-day lives but also for each and every cell of an organism. Information transfer in cells is better known as signal transduction. Numerous elements take part in cellular signalling and generally act through cascades that mediate sensing and processing of stimuli. These molecular circuits precisely detect, amplify, and integrate external signals to generate downstream responses. Thus, perception of a stimulus can lead to changes in gene expression, enzyme activity, localisation of a protein or its half-life, leading to major changes in cell homeostasis. The protein kinase family exemplifies such a major group of signalling proteins. Kinases are enzyme that modifies other proteins by chemically adding a phosphate group to specific amino acids, the most prevalent targets being serine, threonine and tyrosine. How can such a small modification exert profound effects on proteins? Because phosphorylated amino acids in proteins act as new entities, modifying the chemical nature of the protein’s surface, thereby enabling the formation of new protein-protein interactions. Why is it so widely used? Because it is reversible: the kinase adds a phosphate group on a substrate - this modifies the substrate’s properties, which in turn influence its interaction potential - then a phosphatase can remove the phosphate group. This lead to the writer-reader-eraser triad of phosphorylation based signalling. Phosphorylation as a means of communication seems to be even more important in sessile organisms like plants that cannot flea danger or adverse environmental conditions. This can be illustrated by the contribution of the protein kinases family in plants, which represent a much larger fraction of the proteome (the protein ensemble of an organism) compared to other eukaryotes. For example, in the plant model species Arabidopsis thaliana, kinases represent 4% of the proteome compared to ~2% in human, nematode, fruit fly or brewer’s yeast. Of these, two major families, the receptor kinase (RK) family (>600) and the MAPK (Mitogen-Activated Protein Kinases) superfamily (>100), account for 70% of all Arabidopsis protein kinases. Kinases are thus at the forefront of signalling. Our overall research program has been focusing on multiple aspects of cell-cell communication, from pollen-pistil interactions to the role of signalling cascades involving protein kinases in gametophytes development, e.g., the embryo sac of the ovule and the pollen. In this research project, we will focus on the role of a newly assembled MAPK cascade that affects plant growth, development and sexual reproduction, as determined by the analysis of mutant plants lacking these kinases. Using a wide range of experimental approaches, encompassing cell and molecular biology, biochemistry, molecular genetics, genomics, proteomics, and next generation sequencing, we will dissect the functioning of this signalling cascade that includes three kinases: a MAP kinase kinase kinase (or MKKK) that phosphorylate and activates a MAP kinase kinase (or MKK) that in turn phosphorylates a MAP kinase (MAPK or MPK) which then can modulate downstream effectors. These effectors will also be sought in order to better define the involvement of this signalling cascade in the aforementioned biological processes. Our goal is to decipher modules that will be helpful in fundamental, biotechnological, and applied aspects of the plant sciences. Considering that less than five complete MAPK signalling cascades (MKKK-MKK-MPK) have been characterized in plants, our research project will undoubtedly make significant contributions to the field and lead to the creation of tools that can be applied to crop production, protection and breeding.

通信和信息传递是一切，不仅对我们的日常生活，而且对有机体的每个细胞都是如此。细胞内的信息传递更为人所知的是信号转导。许多元件参与细胞信号传递，通常通过级联作用，调节对刺激的感觉和处理。这些分子电路精确地检测、放大和集成外部信号，以产生下游响应。因此，对刺激的感知可以导致基因表达、酶活性、蛋白质定位或半衰期的变化，从而导致细胞内环境平衡的重大变化。蛋白激酶家族就是这样一组重要的信号蛋白。激酶是一种通过在特定氨基酸上化学添加磷酸基团来修饰其他蛋白质的酶，最常见的靶标是丝氨酸、苏氨酸和酪氨酸。如此微小的修饰怎么会对蛋白质产生深远的影响呢？因为蛋白质中的磷酸化氨基酸作为新的实体，改变了蛋白质表面的化学性质，从而能够形成新的蛋白质-蛋白质相互作用。为什么它会被如此广泛地使用？因为它是可逆的：激酶在底物上添加一个磷酸基团-这会改变底物的性质，进而影响其相互作用潜力-然后磷酸酶可以去除磷酸基团。这导致了基于磷酸化的信号的写入器-读取器-擦除器三位一体。作为一种交流手段，磷酸化似乎在固着生物中更重要，比如无法逃脱危险或不利环境条件的植物。这可以通过植物中的蛋白激酶家族的贡献来说明，与其他真核生物相比，蛋白激酶家族在蛋白质组(生物体的蛋白质集合)中所占的比例要大得多。例如，在植物模式物种拟南芥中，激酶占蛋白质组的4%，而在人类、线虫、果蝇或酿酒酵母中只占2%。其中，受体激酶(RK)家族和MAPK(丝裂原激活蛋白激酶)超家族(&gt；100)占拟南芥蛋白激酶总数的70%。因此，激酶处于信号传递的最前沿。我们的整个研究计划一直集中在细胞-细胞通讯的多个方面，从花粉-雌蕊的相互作用到涉及蛋白激酶的信号级联在配子体发育中的作用，例如，胚珠和花粉的胚囊。在这个研究项目中，我们将重点研究新组装的MAPK级联蛋白在植物生长、发育和有性繁殖中的作用，这是通过对缺乏这些激酶的突变植物的分析确定的。使用广泛的实验方法，包括细胞和分子生物学、生物化学、分子遗传学、基因组学、蛋白质组学和下一代测序，我们将剖析这一信号级联的功能，其中包括三个激酶：一个MAP激酶(或MKKK)，它磷酸化并激活一个MAP激酶(或MKK)，MAP激酶(或MKK)进而磷酸化MAP激酶(MAPK或MPK)，然后再调节下游效应器。还将寻找这些效应器，以便更好地定义该信号级联在上述生物过程中的参与。我们的目标是破译在植物科学的基础、生物技术和应用方面有帮助的模块。考虑到目前在植物中发现的完整的MAPK信号级联(MKKK-MKK-MPK)还不到5个，我们的研究项目无疑将对该领域做出重大贡献，并导致可应用于作物生产、保护和育种的工具的创造。