title: Inactivation of the myocyte enhancer factor-2 repressor histone deacetylase-5 by endogenous Ca(2+) //calmodulin-dependent kinase II promotes depolarization-mediated cerebellar granule neuron survival.
abstract: Cerebellar granule neuron (CGN) survival depends on activity of the myocyte enhancer factor-2 (MEF2) transcription factors. Neuronal MEF2 activity is regulated by depolarization via a mechanism that is presently unclear. Here, we show that depolarization-mediated MEF2 activity and CGN survival are compromised by overexpression of the MEF2 repressor histone deacetylase-5 (HDAC5). Furthermore, removal of depolarization induced rapid cytoplasm-to-nuclear translocation of endogenous HDAC5. This effect was mimicked by addition of the calcium/calmodulin-dependent kinase (CaMK) inhibitor KN93 to depolarizing medium. Removal of depolarization or KN93 addition resulted in dephosphorylation of HDAC5 and its co-precipitation with MEF2D. HDAC5 nuclear translocation triggered by KN93 induced a marked loss of MEF2 activity and subsequent apoptosis. To selectively decrease CaMKII, CGNs were incubated with an antisense oligonucleotide to CaMKIIalpha. This antisense decreased CaMKIIalpha expression and induced nuclear shuttling of HDAC5 in CGNs maintained in depolarizing medium. Selectivity of the CaMKIIalpha antisense was demonstrated by its lack of effect on CaMKIV-mediated CREB phosphorylation. Finally, antisense to CaMKIIalpha induced caspase-3 activation and apoptosis, whereas a missense control oligonucleotide had no effect on CGN survival. These results indicate that depolarization-mediated calcium influx acts through CaMKII to inhibit HDAC5, thereby sustaining high MEF2 activity in CGNs maintained under depolarizing conditions.
authors.affiliation: Department of Pharmacology, University of Colorado Health Sciences Center and the Denver Veterans Affairs Medical Center, Denver, Colorado 80262, USA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Linseman
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Bartley
authors.forename: Shoshona S
authors.initials: SS
authors.lastname: Le
authors.forename: Tracey A
authors.initials: TA
authors.lastname: Laessig
authors.forename: Ron J
authors.initials: RJ
authors.lastname: Bouchard
authors.forename: Mary Kay
authors.initials: MK
authors.lastname: Meintzer
authors.forename: Mingtao
authors.initials: M
authors.lastname: Li
authors.forename: Kim A
authors.initials: KA
authors.lastname: Heidenreich
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism*; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors*; D004789:Enzyme Activation; D000939:Epitopes; D005799:Genes, Dominant; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases; D007150:Immunohistochemistry; D064326:MEF2 Transcription Factors; D009154:Mutation; D018006:Myogenic Regulatory Factors; D009474:Neurons / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D010766:Phosphorylation; D011188:Potassium / Q000494:pharmacology; D011233:Precipitin Tests; D020033:Protein Isoforms; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014157:Transcription Factors / Q000037:antagonists & inhibitors*; D014158:Transcription, Genetic
chemical_list: D016895:Culture Media, Serum-Free; D004268:DNA-Binding Proteins; D000939:Epitopes; D056572:Histone Deacetylase Inhibitors; D064326:MEF2 Transcription Factors; D018006:Myogenic Regulatory Factors; D016376:Oligonucleotides, Antisense; D020033:Protein Isoforms; D014157:Transcription Factors; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; C498619:Hdac5 protein, rat; D006655:Histone Deacetylases; D011188:Potassium; D002118:Calcium