Islam M M, Steward R L
Department of Mechanical and Aerospace Engineering.
Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL.
Exp Mech. 2019 Mar;59(3):327-336. doi: 10.1007/s11340-018-00445-4. Epub 2018 Nov 20.
The endothelium has been established to generate intercellular stresses and suggested to transmit these intercellular stresses through cell-cell junctions, such as VE-Cadherin and ZO-1, for example. Although the previously mentioned molecules reflect the appreciable contributions both adherens junctions and tight junctions are believed to have in endothelial cell intercellular stresses, in doing so they also reveal the obscure relationship that exists between gap junctions and intercellular stresses. Therefore, to bring clarity to this relationship we disrupted expression of the endothelial gap junction connexin 43 (Cx43) by exposing confluent human umbilical vein endothelial cells (HUVECs) to a low (0.2 μg/mL) and high (2 μg/mL) concentration of 2,5-dihydroxychalcone (chalcone), a known Cx43 inhibitor. To evaluate the impact Cx43 disruption had on endothelial cell mechanics we utilized traction force microscopy and monolayer stress microscopy to measure cell-substrate tractions and cell-cell intercellular stresses, respectively. HUVEC monolayers exposed to a low concentration of chalcone produced average normal intercellular stresses that were on average 17% higher relative to control, while exposure to a high concentration of chalcone yielded average normal intercellular stresses that were on average 55% lower when compared to control HUVEC monolayers. HUVEC maximum shear intercellular stresses were observed to decrease by 16% (low chalcone concentration) and 66% (high chalcone concentration), while tractions exhibited an almost 2-fold decrease under high chalcone concentration. In addition, monolayer cell velocities were observed to decrease by 19% and 35% at low chalcone and high chalcone concentrations, respectively. Strain energies were also observed to decrease by 32% and 85% at low and high concentration of chalcone treatment, respectively, when compared to control. The findings we present here reveal for the first time the contribution Cx43 has to endothelial biomechanics.
内皮细胞已被证实会产生细胞间应力，并被认为可通过细胞间连接（如血管内皮钙黏蛋白和紧密连接蛋白1等）来传递这些细胞间应力。尽管上述分子反映了黏附连接和紧密连接在内皮细胞间应力中所起的显著作用，但这样做也揭示了间隙连接与细胞间应力之间存在的模糊关系。因此，为了阐明这种关系，我们通过将汇合的人脐静脉内皮细胞（HUVECs）暴露于低浓度（0.2μg/mL）和高浓度（2μg/mL）的2,5 - 二羟基查耳酮（查耳酮，一种已知的Cx43抑制剂）来破坏内皮间隙连接蛋白43（Cx43）的表达。为了评估Cx43破坏对内皮细胞力学的影响，我们分别利用牵引力显微镜和单层应力显微镜来测量细胞 - 基质牵引力和细胞间应力。暴露于低浓度查耳酮的HUVEC单层产生的平均正常细胞间应力相对于对照组平均高出17%，而暴露于高浓度查耳酮时，与对照HUVEC单层相比，产生的平均正常细胞间应力平均低55%。观察到HUVEC最大剪切细胞间应力分别降低了16%（低查耳酮浓度）和66%（高查耳酮浓度），而在高查耳酮浓度下牵引力下降了近2倍。此外，观察到单层细胞速度在低查耳酮浓度和高查耳酮浓度下分别降低了19%和35%。与对照相比，在低浓度和高浓度查耳酮处理下，应变能也分别降低了32%和85%。我们在此展示的研究结果首次揭示了Cx43在内皮生物力学中的作用。
