Beclin-1/LC3-II dependent macroautophagy was uninfluenced in ischemia-challenged vascular endothelial cells.

Autophagy has been extensively studied and occurs in many biological settings. However, a question remains as to whether ischemia enhances Beclin-1/LC3-II-dependent macroautophagy in vascular endothelial cells, as has been previously thought. Furthermore, the effect of the level of autophagy on cell or skin flap survival still requires elucidation. We created a lethal ischemia model in human umbilical vascular endothelial cells (HUVECs), performed quantitative proteomics and bioinformatics analyses, and verified the autophagic status and effect both and . The significantly upregulated proteins encoded by autophagy-related genes (ATGs) included , , , , , , , , and . The significantly enhanced lysosomal proteins were cathepsin B, cathepsin D, lysosome-associated membrane protein 1 (LAMP1), and LAMP2. However, the differentially expressed proteins excluded Beclin-1, microtubule-associated protein light chain 3 (LC3)-I, and LC3-II. Western blot analyses verified that the protein expression levels of Beclin-1, LC3-I, and LC3-II were neither upregulated nor downregulated in ischemia-challenged HUVECs. The autophagic status was not enhanced by rapamycin in ischemic HUVECs but appeared to be inhibited by chloroquine. Our study on rats showed that a downregulation in autophagic status jeopardized skin flap survival. In conclusion, Ischemia neither enhanced nor inhibited Beclin-1/LC3-II-dependent canonical macroautophagy both and , in contradiction to previous studies. An appropriate autophagic homeostasis can minimize cell or skin flap damage.