EIF2a and caspase-12 activation are involved in oxygen-glucose-serum deprivation/restoration-induced apoptosis of spinal cord astrocytes

Astrocytes play an important role in protecting neurons during ischemia and reperfusion in the central nervous system. Although many studies have shown that oxygen-glucose deprivation (OGD) can induce astrocyte apoptosis, the role of PERK/eIF2a/ATF4 integrated stress response (ISR) in astrocyte apoptosis mediated by oxygen-glucose-serum deprivation (OGSD)/restoration remains uncertain. Astrocytes were subjected to a combination of oxygen, glucose, and serum deprivation for 8 h followed by restoration. Hoechst 33342 staining was performed to quantify apoptotic astrocytes and cell viability was assessed with Cell Counting Kit-8 (CCK8). Immunocytochemical analysis and Western blotting for some related molecules, including pancreatic ER stress kinase (PERK), p-PERK, eukaryotic initiation factor 2 alpha (eIF2a), p-eIF2a, activating transcription factor 4 (ATF4), caspase-12, were examined. Caspase activation and apoptosis were detected in neonatal rat astrocytes from spinal cord subjected to OGSD/restoration. We also observed an increase in cytoplasmic staining of p-eIF2a in astrocytes (8 h OGSD/15 min restoration) compared with that of non-treated cells. In addition, we found the sequential activation of PERK, eIF2a, and ATF4 during OGSD/restoration by Western blotting. These results indicate that both the PERK/eIF2a/ATF4 ISR and activation of caspase-12 may be involved in apoptosis of spinal cord astrocytes induced by OGSD/restoration.