Department of Bioengineering and Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA.
Cardiovasc Res. 2011 Jul 1;91(1):124-33. doi: 10.1093/cvr/cvr033. Epub 2011 Feb 1.
High shear stress (HSS) can have significant impact on angiogenesis and atherosclerosis in collateral arteries near the bifurcation and curvature regions. Here, we investigate the spatiotemporal pattern of HSS-induced intracellular calcium alteration.
Genetically encoded biosensors based on fluorescence resonance energy transfer were targeted in the cytoplasm and the endoplasmic reticulum (ER) to visualize the subcellular calcium dynamics in bovine aortic endothelial cells under HSS (65 dyn/cm(2)). Upon HSS application, the intracellular Ca(2+) concentration (Ca(2+)) increased immediately and maintained a sustained high level, while the ER-stored calcium had a significant decrease only after 300 s. The perturbation of calcium influx across the plasma membrane (PM) by the removal of extracellular calcium or the blockage of membrane channels inhibited the early phase of Ca(2+) increase upon HSS application, which was further shown to be sensitive to the magnitudes of shear stress and the integrity of cytoskeletal support. In contrast, Src, phospholipase C(PLC), and the inositol 1,4,5-trisphosphate receptor (IP(3)R) can regulate the late phase of HSS-induced Ca(2+) increase via the promotion of the ER calcium efflux.
The HSS-induced Ca(2+) increase consists of two well-co-ordinated phases with different sources and mechanisms: (i) an early phase due to the calcium influx across the PM which is dependent on the mechanical impact and cytoskeletal support and (ii) a late phase originated from the ER-calcium efflux which is regulated by the Src, PLC, and IP(3)R signalling pathway. Therefore, our work presented new molecular-level insights into systematic understanding of mechanotransduction in cardiovascular systems.
高切应力（HSS）可显著影响分又和弯曲部位附近侧支动脉的血管生成和动脉粥样硬化。在此，我们研究了 HSS 诱导的细胞内钙变化的时空调控模式。
利用基于荧光共振能量转移的遗传编码生物传感器，将其靶向定位于细胞质和内质网（ER），以可视化 HSS（65dyn/cm(2)）作用下牛主动脉内皮细胞的亚细胞钙动力学。HSS 施加后，细胞内 Ca(2+)浓度(Ca(2+))立即升高并维持在较高水平，而 ER 中储存的钙仅在 300s 后才显著减少。去除细胞外钙或阻断膜通道可干扰质膜（PM）中钙内流，从而抑制 HSS 施加后 Ca(2+)的早期升高，这进一步表明该过程对切应力的幅度和细胞骨架支撑的完整性敏感。相比之下，Src、PLC 和肌醇 1,4,5-三磷酸受体（IP(3)R）可通过促进 ER 钙外排来调节 HSS 诱导的 Ca(2+)的晚期升高。
HSS 诱导的 Ca(2+)升高由两个具有不同来源和机制的协调良好的相组成：（i）早期相是由于 PM 中的钙内流引起的，这取决于机械冲击和细胞骨架支撑；（ii）晚期相源自 ER 钙外排，由 Src、PLC 和 IP(3)R 信号通路调节。因此，我们的工作为系统理解心血管系统中的力学转导提供了新的分子水平见解。
