utophagy 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

in vitro

and

in vivo

. The significantly upregulated proteins encoded by autophagy-related genes (ATGs) included

ATG2A

ATG3

ATG4B

ATG5

ATG7

ATG9A

ATG12

ATG16

and

ATG101

. 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

in vivo

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

in vitro

and

in vivo

in contradiction to previous studies. An appropriate autophagic homeostasis can minimize cell or skin flap damage.