title: Induction of ER stress in response to oxygen-glucose deprivation of cortical cultures involves the activation of the PERK and IRE-1 pathways and of caspase-12.
abstract: Disturbance of calcium homeostasis and accumulation of misfolded proteins in the endoplasmic reticulum (ER) are considered contributory components of cell death after ischemia. However, the signal-transducing events that are activated by ER stress after cerebral ischemia are incompletely understood. In this study, we show that caspase-12 and the PERK and IRE pathways are activated following oxygen-glucose deprivation (OGD) of mixed cortical cultures or neonatal hypoxia-ischemia (HI). Activation of PERK led to a transient phosphorylation of eIF2α, an increase in ATF4 levels and the induction of gadd34 (a subunit of an eIF2α-directed phosphatase). Interestingly, the upregulation of ATF4 did not lead to an increase in the levels of CHOP. Additionally, IRE1 activation was mediated by the increase in the processed form of xbp1, which would be responsible for the observed expression of edem2 and the increased levels of the chaperones GRP78 and GRP94. We were also able to detect caspase-12 proteolysis after HI or OGD. Processing of procaspase-12 was mediated by NMDA receptor and calpain activation. Moreover, our data suggest that caspase-12 activation is independent of the unfolded protein response activated by ER stress.
authors.affiliation: Institut de Neurociencies and Universitat Autònoma de Barcelona, Barcelona, Spain.
authors.forename: N
authors.initials: N
authors.lastname: Badiola
authors.forename: C
authors.initials: C
authors.lastname: Penas
authors.forename: A
authors.initials: A
authors.lastname: Miñano-Molina
authors.forename: B
authors.initials: B
authors.lastname: Barneda-Zahonero
authors.forename: R
authors.initials: R
authors.lastname: Fadó
authors.forename: G
authors.initials: G
authors.lastname: Sánchez-Opazo
authors.forename: J X
authors.initials: JX
authors.lastname: Comella
authors.forename: J
authors.initials: J
authors.lastname: Sabriá
authors.forename: C
authors.initials: C
authors.lastname: Zhu
authors.forename: K
authors.initials: K
authors.lastname: Blomgren
authors.forename: C
authors.initials: C
authors.lastname: Casas
authors.forename: J
authors.initials: J
authors.lastname: Rodríguez-Alvarez
mesh_terms: D051701:Activating Transcription Factor 4 / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism; D002154:Calpain / Q000378:metabolism; D053454:Caspase 12 / Q000378:metabolism*; D018929:Cell Culture Techniques; D015687:Cell Hypoxia; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000502:physiology*; D004789:Enzyme Activation; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D005947:Glucose / Q000172:deficiency*; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D014176:Protein Biosynthesis; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D000071701:Regulatory Factor X Transcription Factors; D015398:Signal Transduction; D013312:Stress, Physiological; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation; D000071717:X-Box Binding Protein 1; D019892:eIF-2 Kinase / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP
chemical_list: D051701:Activating Transcription Factor 4; D000943:Antigens, Differentiation; D002154:Calpain; D053454:Caspase 12; D004268:DNA-Binding Proteins; D015852:Eukaryotic Initiation Factor-2; D005947:Glucose; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D016194:Receptors, N-Methyl-D-Aspartate; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; D019892:eIF-2 Kinase; C497110:Atf4 protein, rat; C051684:GRP78 protein, rat; D000091342:Endoplasmic Reticulum Chaperone BiP; C489287:Ppp1r15a protein, rat; C000605545:Xbp1 protein, rat; C018551:glucose-regulated proteins; C486557:Ern2 protein, rat; C506443:Casp12 protein, rat