Temporal assessment of histone H3 phospho-acetylation and casein kinase 2 activation in dentate gyrus from ischemic rats.
Hippocampal dentate gyrus possesses an exceptional capacity of adaptation to ischemic insults. Recently, using a transient global ischemic model in the adult rat, we identified a neuroprotective signalling cascade in the dentate gyrus involving calcium/calmodulin-dependent protein kinase IV (CaMKIV), cyclic AMP response element (CRE)-binding protein (CREB) and brain-derived neurotrophic factor (BDNF), a major regulator of survival. We have shown that intracerebroventricular injections of anti-BDNF and anti-CREB are sufficient to cause substantial tissular damages and apoptotic deaths in late periods (48-72 h) after ischemia. Herein, we provide immunohistochemical and biochemical evidence that antibody-induced impairment of the protective CaMKIV/CREB/BDNF pathway induces an apparent duality of response in the dentate gyrus. The experimental protocol is performed as follows: (a) rats are anesthetized and vertebral arteries are occluded by electrocauterization; (b) on the following day, transient global ischemia is produced by occlusion of carotid arteries for 25 min; (c) finally, rats are infused with the pharmacologic agents into the left cerebral ventricle and then perfusion-fixed at different time points after ischemia for immunohistochemical and immunoblotting analyses. After infusion with anti-CaMKIV, phosphorylation of mitogen-activated protein kinases (MAPK) MKK3, MKK6 and p38 and phospho-acetylation of histone H3 occur at 6 h after ischemia without presence of any caspase-9 activation and cellular injuries. In contrast, infusion of anti-BDNF or anti-CREB surprisingly results in a remarkable stimulation of casein kinase 2 (CK2) and caspase-9 activities at 48-72 h post-insult. This is accompanied by the disappearance of phosphorylation of MKK(3/6) and p38 and phospho-acetylation of histone H3. These results suggest that: (1) activation of a MKK(3/6)/p38/H3 cascade at early periods post-ischemia may be capable of causing a short transient protective effect in the dentate gyrus; (2) CK2 might be implicated in inhibition of activity of molecules such as MKK(3/6), p38 and deacetylases at late periods post-insult, thereby promoting injuries and cell deaths in the dentate cell layer.
Blanquet
P R
PR
Laboratoire Développement et Vieillissement du Système Nerveux, UMR 7102 CNRS-UPMC (Neurobiologie des Processus Adaptatifs), Université P & M Curie, 9 Quai Saint-Bernard, Bâtiment B, 4(e)Etage, Boîte 14, 75005, Paris, France. pr.blanquet@free.fr
Mariani
J
J
Fournier
B
B
D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism* / Q000503:physiopathology; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4 / Q000378:metabolism; D047390:Casein Kinase II / Q000378:metabolism*; D053453:Caspase 9 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D019610:Cytoprotection / Q000187:drug effects / Q000502:physiology*; D018891:Dentate Gyrus / Q000378:metabolism* / Q000503:physiopathology; D004195:Disease Models, Animal; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006657:Histones / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D008297:Male; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology; D013997:Time Factors
D019208:Brain-Derived Neurotrophic Factor; D017362:Cyclic AMP Response Element-Binding Protein; D004791:Enzyme Inhibitors; D006657:Histones; D047390:Casein Kinase II; D054734:Calcium-Calmodulin-Dependent Protein Kinase Type 4; C517686:Camk4 protein, rat; D053453:Caspase 9