Inhibition of the JNK/AP-1 pathway reduces neuronal death and improves behavioral outcome after neonatal hypoxic-ischemic brain injury.
Perinatal hypoxic-ischemic (HI) brain damage continues to be a major clinical problem. We investigated the contribution of the MAP kinase c-Jun N-terminal kinase (JNK), to neonatal HI brain damage. JNK regulates several transcriptional (via AP-1 activation) and non-transcriptional processes involved in brain damage such as inflammation and cell death/survival. P7 rats were subjected to HI by unilateral carotid artery occlusion and hypoxia. HI-induced activation of cerebral AP-1 peaked at 3-6h post-HI. Intraperitoneal administration of the JNK-inhibitor TAT-JBD immediately after HI prevented AP-1 activation. TAT-JBD treatment within 3h after HI reduced early neuronal damage by approximately 30%. JNK/AP-1 inhibition did not reduce HI-induced cytokine/chemokine expression. Analysis of indicators of apoptotic cell death revealed that TAT-JBD markedly reduced the HI-induced increase in active caspase 3. However, the upstream mediators of apoptosis: active caspase 8, cleaved Bid, mitochondrial cytochrome c release and caspase 9 cleavage were not reduced after TAT-JBD. TAT-JBD inhibited the HI-induced increase in Smac/DIABLO, an inhibitor of IAPs that prevent activation of caspase 3. TAT-JBD treatment also reduced cleavage of alpha-fodrin, indicating that calpain-mediated brain damage was reduced. Neuroprotection by TAT-JBD treatment was long-lasting as gray- and white matter damage was diminished by approximately 50% at 14 weeks post-HI concomitantly with marked improvement of sensorimotor behavior and cognitive functioning. In conclusion, JNK inhibition by TAT-JBD treatment reduced neonatal HI brain damage with a therapeutic window of 3h and long-lasting anatomical and behavioral improvements. We propose that inhibition of mitochondrial Smac/DIABLO release and calpain activation contribute to neuroprotection by TAT-JBD.
Nijboer
Cora H
CH
Laboratory of Psychoneuroimmunology, University Medical Center Utrecht, Utrecht, The Netherlands.
van der Kooij
Michael A
MA
van Bel
Frank
F
Ohl
Frauke
F
Heijnen
Cobi J
CJ
Kavelaars
Annemieke
A
D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001522:Behavior, Animal; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D020925:Hypoxia-Ischemia, Brain / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D010455:Peptides / Q000494:pharmacology; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D045442:Rotarod Performance Test; D015398:Signal Transduction / Q000187:drug effects; D018808:Transcription Factor AP-1 / Q000378:metabolism
D010455:Peptides; C548497:Tat-JBD peptide; D018808:Transcription Factor AP-1; D048031:JNK Mitogen-Activated Protein Kinases; D053148:Caspase 3; D053453:Caspase 9