Differential protein expression in brain capillary endothelial cells induced by hypoxia and posthypoxic reoxygenation

Cerebral ischemia causes functional alteration of the blood-brain barrier, formed by brain capillary endothelial cells (BCEC). Changes in protein expression and activity of selected differentially expressed enzymes were investigated in BCEC subjected to hypoxia (24 h) alone or followed by a 24-h reoxygenation. BCEC proteins were isolated, separated by 2-DE, and identified by MALDI-MS. Computer-based 2-D gel analysis identified 21 up-regulated proteins and 4 down-regulated proteins after hypoxia alone and 9 proteins that were further up-regulated after posthypoxic reoxygenation. The expression of the majority of hypoxia-induced proteins was reduced toward control levels during reoxygenation. The most prominent changes were identified for glycolytic enzymes (e.g., phosphoglycerate kinase), proteins of the ER (e.g., calreticulin), and cytoskeletal (e.g., vimentin) proteins. The results indicate that BCEC respond to hypoxia/reoxygenation by adaptive up-regulation of proteins involved in the glycolysis, protein synthesis, and stress response.