Microtubule‐Dependent Apical Translocation of Mitochondria in Pulmonary Endothelial Cells Under Shear Stress

Abstract

Mitochondria are motile organelles that play key roles in numerous cellular pathways including calcium regulation, apoptosis, and ATP production. Mitochondrial apical translocation may be an essential response to the changing requirements under shear stress since shear stress directly affects the apex of polarized pulmonary endothelial cells. We hypothesize therefore that flow induces mitochondrial translocation to the apex of pulmonary endothelial cells. To study this idea, rat pulmonary microvascular endothelial cells (PMVEC) were subjected to shear stress at 14 dynes/cm2 over a period of three to six hours. MitoTracker Red 580 (MTR) was utilized to image and track mitochondrial movement. The area of the MTR signal at the apex, corresponding to localization of the mitochondria mass, was quantified in 3D‐reconstructed individual cells at different time points and plotted as a percent of total apical area. Our results show that the apical MTR signal increased significantly at 3 and 6 h of shear‐stress compared with 0 h of flow, indicating flow‐induced mitochondrial translocation to the apex. Treatment with 50 nM nocodozole abolished the mitochondrial translocation response with shear stress. We conclude that mitochondria translocate to the cellular apex under shears stress and that microtubule integrity is essential for this translocation.