Collaborative Research: Mathematical, Numerical, and Experimental Investigation of Flow Sensing by the Primary Cilium

这个由三名研究人员组成的跨学科团队将整合数学模型、数值模拟和实验来研究围绕初级纤毛机械感觉作用的关键基本问题。初级纤毛是单生的（每个细胞一个），不动的，天线状的微管细胞器，从几乎每个哺乳动物细胞的表面延伸出来。机械刺激（如血流）引起初级纤毛偏转，启动下游信号级联到细胞的其余部分。原发性纤毛缺陷与动脉粥样硬化、骨质疏松和癌症有关。然而，从初级纤毛弯曲到细胞反应的生化信号通路仍然是一个复杂且未解决的问题，这将由三个pi来解决。本研究结果将进一步加深我们对初级纤毛亚细胞力学感知的理解，并为设计治疗各种由初级纤毛缺陷引起的人类疾病的治疗策略奠定基础。这些项目将吸引本科生和研究生进行跨学科研究，研究成果将为数学生物学、生物物理学、生物医学工程和医学提供新的方法。在这个项目中开发的方法和技术将超越初级纤毛的背景，并扩展到具有机械诱导细胞功能的其他问题，例如血管张力的调节。长期以来，人们一直推测，在随后的细胞生化信号和反应（如细胞骨架模式的改变或离子和溶剂运输的改变）中，触发细胞内钙释放作为第二信使，但最近使用遗传编码钙指标的实验反驳了一系列细胞的初级纤毛钙反应性。因此，建立对初级纤毛在亚细胞机械感知中的作用的基本认识是必要的。鉴别从纤毛弯曲到随后的生化信号传导途径的一个主要挑战是将初级纤毛的贡献与细胞对相同机械刺激的直接反应分离开来。通过使用光学陷阱，PI Resnick能够弯曲单个初级纤毛，而不会对细胞的其余部分施加力，从而为深入了解缺失的途径提供了很好的机会。将该实验技术与数学建模（PI Young）和数值模拟（PI Peng）相结合，该团队旨在(1)表征初级纤毛的力学特性，(2)确定纤毛与细胞骨架之间的耦合，以及(3)确定信号激活的时间尺度和特征，以量化纤毛介导的流量传感。这三个目标的结果将推进初级纤毛的数学建模以及它如何与细胞内信号通路耦合。该奖项是由分子和细胞生物科学部的细胞动力学和功能项目以及DMS的生命科学风险基金共同资助的。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 interdisciplinary team of three investigators will integrate mathematical modeling, numerical simulations, and experiments to investigate key fundamental issues surrounding the mechanosensory roles of primary cilia. Primary cilia are solitary (one per cell), immotile, antenna-like microtubule-based organelles extending from the surface of nearly every mammalian cell. Mechanical stimuli (such as blood flow) cause deflection of the primary cilium, initiating downstream signaling cascades to the rest of the cell. Defects in primary cilia have been associated with atherosclerosis, osteoporosis, and cancer. Yet the biochemical signaling pathways from primary cilia bending to cellular responses remain a complex and unsolved problem that will be addressed by the three PIs. Results from the proposed research will further our understanding of subcellular mechanosensing of primary cilia, and will lay the foundation for designing therapeutic strategies to treat various human diseases due to defected primary cilia. The PIs will engage both undergraduate and graduate students to conduct interdisciplinary research, and results from the proposed research can provide new approaches in mathematical biology, biophysics, biomedical engineering and medicine. The methods and techniques to be developed in this project will go beyond the context of primary cilia and extend to other problems featuring mechanically induced cellular functions, for example, in the regulation of vascular tone. Long speculated to trigger intracellular calcium release as a second messenger for subsequent cellular biochemical signaling and responses (such as change in patterns of cytoskeleton or altered ion and solvent transport), recent experiments using genetically-coded calcium indicators refuted the calcium-responsiveness of primary cilia for a range of cells. Thus it is imperative to establish fundamental understanding of the role of primary cilia in subcellular mechanosensing. One main challenge to identify the pathway(s) from cilium bending to subsequent bio-chemical signaling is to isolate primary cilium contribution from the rest of the cell responding directly to the same mechanical stimuli. By using an optical trap, PI Resnick is able to bend a single primary cilium without exerting force on the rest of the cell, thus providing a great opportunity for insight to the missing pathways. Combining this experimental technique with mathematical modeling (PI Young) and numerical simulations (PI Peng), the team aims to (1) characterize the mechanical properties of the primary cilium, (2) qualify the coupling between cilium and cytoskeleton, and (3) identify the time scales and characteristics of signaling activation to quantify ciliary-mediated flow sensing. Results from these three aims will advance the mathematical modeling of the primary cilium and how it couples to the intracellular signaling pathways.This award is co-funded with the Cellular Dynamics and Function program in Division of Molecular and Cellular Biosciences, and the Life Science Venture Fund in DMS.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.