Signal transduction mechanisms of the chondrocyte

软骨细胞的信号转导机制

• 批准号: RGPIN-2017-04531
• 负责人: Clark, Andrea
• 金额: $ 1.82万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=647763
• 关键词: Signal; transduction; mechanisms; chondrocyte

Articular cartilage is a soft tissue covering the surfaces of bones within synovial joints. Cartilage is compressed and relaxed during joint motion leading to changes in osmotic stress as fluid is extruded and then imbibed by the proteoglycan rich matrix. As the only cells of cartilage, chondrocytes play a critical role in maintaining the extracellular matrix. Chondrocytes are sensitive to mechanical and chemical changes in their locale and reciprocate with a variety of biological responses.******The long term objective of my research program is to identify and characterize signal transduction mechanisms through which chondrocytes respond biologically to mechanical and chemical changes in cartilage. This advance in knowledge is applicable for cartilage tissue engineers in the design of bioreactor systems. Harnessing the effects of osmotic stress on chondrocyte biology, for example, is scalable at low cost (adding sucrose or water).******Primary cilia are non-motile with an axoneme consisting of a 9+0 doublet arrangement of tubulin tubules. Although immotile, the cilium can alter its length by regulating microtubule assembly, disassembly and bidirectional intraflagellar transport. Chondrocyte cilia are 1-2 µm long and host numerous receptors and signaling molecules along their axoneme including the primary chondrocyte osmosensor, transient receptor potential vanilloid 4. In response to osmotic stress, chondrocyte cilia shorten and reorganization of the actin cytoskeleton occurs, the latter requiring the activation of gelsolin. Furthermore, deciliated chondrocytes do not respond to osmotic stimuli and cells lacking gelsolin show a reduction in ciliogenesis. Together these data suggest a critical role for primary cilia and their shortening in chondrocyte transduction of osmotic stress and interplay with the actin cytoskeleton in this transduction. ******The short term objective of my research program is to investigate the role of the primary cilium and its shortening in chondrocyte transduction of osmotic stress. We will examine if cilia shortening is necessary for chondrocyte osmotransduction and/or if cilia length regulates chondrocyte sensitivity to osmotic stress. Further we will investigate the role of actin dynamics in changes to cilial length. Finally we will manipulate osmotic stress and cilial length in neo-cartilage constructs and measure the effects on chondrogenesis.******As such this proposal will provide significant advances in knowledge to the natural sciences and engineering that are critical to the fields of cell biology and tissue engineering. Almost all mammalian cells possess a single primary cilium and many are exposed to osmotic stress, thus our findings will be applicable to numerous cell systems.

关节软骨是覆盖在滑膜关节骨表面的软组织。在关节运动过程中，软骨被压缩和放松，流体被挤压，然后被富含蛋白多糖的基质吸收，从而导致渗透应力的变化。软骨细胞作为软骨的唯一细胞，在维持细胞外基质中起着至关重要的作用。软骨细胞对其所在位置的机械和化学变化很敏感，并与各种生物反应相互作用。******我的研究计划的长期目标是识别和表征信号转导机制，通过这种机制，软骨细胞对软骨的机械和化学变化做出生物反应。这种知识的进步适用于软骨组织工程师设计生物反应器系统。例如，利用渗透压力对软骨细胞生物学的影响，可以以低成本（添加蔗糖或水）进行扩展。******初级纤毛是不运动的，轴素由9+0双排微管组成。虽然纤毛是不运动的，但它可以通过调节微管的组装、拆卸和双向的鞭毛内运输来改变其长度。软骨细胞纤毛长1-2µm，轴突上有许多受体和信号分子，包括初级软骨细胞渗透传感器、瞬时受体电位香兰素4。作为对渗透胁迫的反应，软骨细胞纤毛缩短，肌动蛋白细胞骨架发生重组，后者需要凝胶蛋白的激活。此外，脆弱的软骨细胞对渗透刺激没有反应，缺乏凝胶的细胞纤毛发生减少。综上所述，这些数据表明初级纤毛及其缩短在渗透应激的软骨细胞转导中起着关键作用，并与肌动蛋白细胞骨架在这一转导中相互作用。******我的研究计划的短期目标是研究初级纤毛及其缩短在渗透应激的软骨细胞转导中的作用。我们将研究纤毛的缩短是否对软骨细胞渗透转导是必要的和/或纤毛的长度是否调节软骨细胞对渗透应激的敏感性。我们将进一步研究肌动蛋白动力学在纤毛长度变化中的作用。最后，我们将在新软骨结构中操纵渗透应力和纤毛长度，并测量对软骨形成的影响。******因此，该提案将为自然科学和工程领域提供重要的知识进步，这对细胞生物学和组织工程领域至关重要。几乎所有的哺乳动物细胞都具有单一的初级纤毛，并且许多细胞都暴露于渗透胁迫下，因此我们的发现将适用于许多细胞系统。