Collaborative Research: Quantitative Principles behind the Spatio-Temporal Oscillation of Intracellular Calcium

本项目将研究细胞内钙离子在极性细胞生长过程中如何在空间和时间上发生快速振荡，这一机制在植物受精过程中花粉管尖端生长、真菌菌丝延伸、肿瘤细胞转移等过程中具有极其重要的意义。研究人员将从生长中的拟南芥花粉管中收集时空钙离子图像数据，并利用细胞生物学家、数学家和统计学家的联合专业知识，采用迭代建模-实验测试方法，旨在发现调节花粉管尖端快速和定向生长的未知定量机制。从这个项目中获得的基本知识可能有助于开发化学或遗传疾病治疗策略，因为细胞极化与许多人类疾病和癌症有关。研究结果有助于了解真菌病原体，因为花粉管尖端的生长类似于入侵真菌菌丝的生长。本项目涉及本科生、研究生和博士后。计算和模拟工具和理论结果将公开提供，以便更多地使用和促进这些领域的其他研究人员。本项目由数学科学部数学生物学项目、分子与细胞生物科学部细胞动力学与功能项目、综合有机体系统生理机制与生物力学项目联合资助。钙具有广泛的生物学重要性，不仅需要骨骼发育，而且作为调节大量细胞过程（如极性细胞生长）的信号。细胞内钙振荡提供了一个关键的时空钙信号，但其潜在的调控机制仍不清楚。拟建项目拟南芥花粉管极性生长作为模型系统。实验数据表明，振荡型花粉管顶端生长受两个相互交织的关键调控因子的时空振荡控制：定位于顶端质膜（细胞边界）的ROP1 GTPase活性和细胞质内聚焦于顶端的钙梯度。为了定量地阐明这些相互依存的关系和系统时空振荡的潜在机制，我们将开发一个二维钙梯度模型来表征尖端聚焦细胞内钙梯度的形成以及产生时空振荡的ROP1和钙梯度的反应-扩散激活剂-抑制剂系统。ROP1和钙动力学也将在3D中制定，以阐明快速尖端生长和生长重定向之间的机制联系。提出的研究将建立新的设计原则，强调快速的时空振荡，作为一种共同的调节机制和组织许多细胞功能的发育策略。这项工作还将描述钙梯度和振荡产生的定量机制，钙梯度和振荡是所有细胞生物中常见的钙信号，对广泛的生物系统具有重大影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will study how calcium ions in cells sometimes undergo rapid oscillations in space and time during polar cell growth, a mechanism that is extremely important during pollen tube tip growth during plant fertilization, extension of fungal hyphae, and tumor cell metastasis. Spatiotemporal calcium ion image data will be collected from growing Arabidopsis pollen tubes and the investigators will undertake an iterative modeling-experimental testing approach, drawing on joint expertise from cell biologists, mathematicians and statisticians, aimed at discovering the unknown quantitative mechanisms that modulate rapid and directed pollen tube tip growth. The fundamental knowledge gained from this project may aid development for chemical or genetic disease treatment strategies, since cell polarization is involved in many human diseases and cancers. Results could assist with understanding fungal pathogens, because pollen tube tip growth is analogous to that of invasive fungal hyphae. This interdisciplinary project involves undergraduate, graduate students and postdoctoral trainees. Computational and simulation tools and theoretical results will be made publicly available to enable greater use and facilitate other researchers in these fields. This project is funded jointly by the Division of Mathematical Sciences Mathematical Biology Program, the Division of Molecular and Cellular Biosciences Cellular Dynamics and Function Program, and the Division of Integrative Organismal Systems Physiological Mechanisms and Biomechanics Program.Calcium is of broad biological importance, needed not only for bone development but also as a signal to regulate a vast number of cellular processes such as polar cell growth. Intracellular calcium oscillation provides a key spatiotemporal calcium signal, but the underlying mechanisms regulating mechanisms remain largely unknown. The proposed project will use Arabidopsis pollen tube polar growth as a model system. Experimental data suggests that oscillatory pollen tube tip growth is controlled by the spatiotemporal oscillation of two intertwined key regulators: the ROP1 GTPase activity localized to the apical plasma membrane (cell boundary) and the tip-focused calcium gradient within the cell cytoplasm. To quantitatively elucidate these interdependent relationships and the underlying mechanism for the spatiotemporal oscillation of the system, we will develop a 2D calcium gradient model to characterize the formation of tip-focused intracellular calcium gradient and a reaction-diffusion activator-inhibitor system of ROP1 and calcium gradients that generate spatiotemporal oscillations. ROP1 and calcium dynamics will also be formulated in 3D to elucidate mechanistic linkage between rapid tip growth and growth redirection. The proposed research will establish new design principles underscoring rapid spatiotemporal oscillations that serve as a common regulatory mechanism and organize developmental strategies for many cell functions. This work will also characterize the quantitative mechanisms underlying the generation of calcium gradients and oscillations that are common calcium signals in all cellular organisms, with significant impact on a broad range of biological systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.