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建模、数值模拟和实验，以调查围绕初级纤毛的机械传感作用的关键基本问题。初生纤毛是单生的(每个细胞一个)，不活动，几乎从每个哺乳动物细胞的表面延伸出来的天线状微管为基础的细胞器。机械刺激(如血流)引起初级纤毛的偏转，启动下行信号级联到细胞的其余部分。初级纤毛缺陷与动脉粥样硬化、骨质疏松症和癌症有关。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而未解决的问题，将由三个PI来解决。本研究的结果将进一步加深我们对初级纤毛亚细胞机械传感的理解，并将为设计治疗因初级纤毛缺陷引起的各种人类疾病的治疗策略奠定基础。PIS将邀请本科生和研究生进行跨学科研究，拟议研究的结果可以为数学生物学、生物物理学、生物医学工程和医学提供新的方法。这个项目中将要开发的方法和技术将超越初级纤毛的背景，扩展到其他以机械诱导的细胞功能为特征的问题，例如，在调节血管张力方面。长期以来，人们一直推测，细胞内的钙释放是随后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)的第二信使，最近使用遗传编码的钙指示剂的实验驳斥了初级纤毛对一系列细胞的钙反应。因此，必须建立对初级纤毛在亚细胞机械感觉中的作用的基本了解。确定从纤毛弯曲到后续生化信号的通路(S)的一个主要挑战是将初级纤毛的贡献从细胞的其余部分分离出来，这些细胞直接对相同的机械刺激做出反应。通过使用光学陷阱，Pi Resnick能够弯曲单个初级纤毛，而不对细胞的其余部分施力，从而为深入了解缺失的路径提供了一个很好的机会。将这项实验技术与数学模型(Pi Young)和数值模拟(Pi Peng)相结合，该团队的目标是(1)表征初级纤毛的机械特性，(2)鉴定纤毛和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感应。这三个目标的结果将推进初级纤毛的数学模型及其如何耦合到细胞内信号通路。该奖项是与分子和细胞生物科学部门的细胞动力学和功能计划以及DMS的生命科学风险基金共同资助的。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.