Opposite reaction of ERK and JNK in ischemia vulnerable and resistant regions of hippocampus: involvement of mitochondria.
Delayed ischemic death of neurones is observed selectively in CA1 region of hippocampus at 3-4 days of reperfusion. Signals generated immediately during and after ischemia are further propagated by a variety of kinases, proteases and phosphatases. Tissue samples from dorsal (vulnerable) and abdominal (resistant) parts of gerbil hippocampi were collected to determine the activation state of key signaling molecules: Akt, Raf-1, JNK, ERK1/2 in the course of reperfusion after 5 min of global cerebral ischemia. Western blot analysis of phosphorylated forms of the kinases revealed persistent activation of JNK, being limited mostly to vulnerable CA1 region. On the contrary, activation of ERK, although observed transiently in both parts, was enhanced for a longer time in the abdominal hippocampus. The levels of the active/phosphorylated Akt and Raf-1 kinases did not change significantly during the recovery period. No significant correlation between postischemic JNK activation and c-Jun phosphorylation or its contribution to AP1-like complex formation was found. In contrast, the amount of active JNK linked with mitochondrial membranes was significantly increased and preceded neuronal death in CA1. In the same period of time the AP1 complex, augmented in CA1 region, did not appear to contain a classical c-Fos protein. These results are consistent with the theory that either long-lasting activation of JNK and/or contrasting ERK and JNK activities in critical time of reperfusion, contribute to selective apoptosis of CA1 neurons. This, in connection with the translocation of activated JNK to mitochondria and time/regional differences in AP1 binding protein complexes can affect final postischemic outcome.
Zablocka
Barbara
B
Molecular Biology Unit, Medical Research Centre, Polish Academy of Sciences, 5 Pawińskiego Street, 02-106 Warsaw, Poland.
Dluzniewska
Joanna
J
Zajac
Halina
H
Domańska-Janik
Krystyna
K
Duzniewska
Joanna
J
D000818:Animals; D002545:Brain Ischemia / Q000201:enzymology* / Q000503:physiopathology; D002544:Cerebral Infarction / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006624:Hippocampus / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D048031:JNK Mitogen-Activated Protein Kinases; D008297:Male; D008928:Mitochondria / Q000201:enzymology* / Q000473:pathology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009410:Nerve Degeneration / Q000201:enzymology* / Q000503:physiopathology; D009474:Neurons / Q000201:enzymology* / Q000473:pathology; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D011930:Reaction Time / Q000502:physiology; D015427:Reperfusion Injury / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology; D018808:Transcription Factor AP-1 / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology
D011518:Proto-Oncogene Proteins; D018808:Transcription Factor AP-1; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D019908:Proto-Oncogene Proteins c-raf; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases