Hypoxia destroys the microstructure of microtubules and causes dysfunction of endothelial cells via the PI3K/Stathmin1 pathway

Endothelial cells (EC) are sensitive to changes in the microenvironment, including hypoxia and ischemia. Disruption of the microtubular network has been reported in cases of ischemia. However, the signaling pathways involved in hypoxia-induced microtubular disruption are unknown. The

Thus, our data demonstrate that hypoxia induced the production of ROS and damaged EC function by destroying the microtubular structure through the PI3K/stathmin1 pathway.

HUVECs were cultured under normoxic or hypoxic conditions and pretreated with or without colchicine or paclitaxel. The MTT assay, Transwell assay, trans-endothelial permeability assay, and 5-bromo-2'-deoxy-uridine staining were used to test the survival rate, migration, permeability, and proliferation of cells, respectively. Transmission electron microscopy and phalloidin staining were used to observe the microstructure and polymerization of microtubules. The results show that the functions of HUVECs and the microtubular structure were destroyed by hypoxia, but were protected by paclitaxel and a reactive oxygen species (ROS) inhibitor. We further used western blot, a luciferase assay, and co-immunoprecipitation to describe a non-transcription-independent mechanism for PI3K activation-inhibited microtubular stability mediated by Stathmin1, a PI3K interactor that functions in microtubule depolymerization. Finally, we determined that hypoxia and ROS blocked the interaction between PI3K and Stathmin1 to activate disassembly of microtubules.