Effect of Spatial Heterogeneity and Colocalization of eNOS and Capacitative Calcium Entry Channels on Shear Stress-Induced NO Production by Endothelial Cells: A Modeling Approach

Abstract

Introduction Colocalization of endothelial nitric oxide synthase (eNOS) and capacitative Ca2+ entry (CCE) channels in microdomains such as cavaeolae in endothelial cells (ECs) has been shown to significantly affect intracellular Ca2+ dynamics and NO production, but the effect has not been well quantified. Methods We developed a two-dimensional continuum model of an EC integrating shear stress-mediated ATP production, intracellular Ca2+ mobilization, and eNOS activation to investigate the effects of spatial colocalization of plasma membrane eNOS and CCE channels on Ca2+ dynamics and NO production in response to flow-induced shear stress. Our model examines the hypothesis that subcellular colocalization of cellular components can be critical for optimal coupling of NO production to blood flow. Results Our simulations predict that heterogeneity of CCE can result in formation of microdomains with significantly higher Ca2+ compared to the average cytosolic Ca2+. Ca2+ buffers with lower or no mobility further enhanced Ca2+ gradients relative to mobile buffers. Colocalization of eNOS to CCE channels significantly increased NO production. Conclusions Our results provide quantitative understanding for the role of spatial heterogeneity and the compartmentalization of signals in regulation of shear stress-induced NO production.

Mathematical Model Predicts Effective Strategies to Inhibit VEGF-eNOS Signaling

“…We tuned and estimated the unknown model parameters in this module by fitting the simulated IP3 activation and intracellular Ca 2+ dynamics upon VEGF stimulation to the datasets of HUVEC cells from Faehling et al [21]. As the single cell datasets from this study exhibit large cell to cell heterogeneity, as is the case with other papers presenting EC Ca 2+ influx data [115,116], we estimated the averaged levels of Ca 2+ and IP3 from the datasets, representing an average cell, and used these values in model training. We assume the basal level of intracellular Ca 2+ to be 50 nM [21,116].…”

Cracking the Endothelial Calcium (Ca2+) Code: A Matter of Timing and Spacing

“…A seminal investigation by the Blatter group on CPAE cells has shown that the endothelial SOCE is selectively coupled to eNOS while being seemingly insensitive to InsP 3 -induced ER Ca 2+ release [66,157]. In agreement with this finding, endothelial SOCs are also primarily located within caveolae, and this structural feature may have profound pathological implications [61,158,159]. Reducing membrane cholesterol can impair caveolar integrity and inhibit agonist-induced SOCE in pulmonary artery endothelial cells in a rat model of chronic hypoxia-induced pulmonary hypertension [160].…”