title: Inhibition of multiple pathways accounts for the antiapoptotic effects of flavopiridol on potassium withdrawal-induced apoptosis in neurons.
abstract: Serum and potassium (S/K) deprivation is a well-known apoptotic model in cerebellar granule neurons (CGNs), used to study the efficacy of potential neuroprotective drugs. The objective of this study was to determine the pathways involved in the neuroprotective role of flavopiridol, a pan-inhibitor of cyclin-dependent kinases (CDKs), upon S/K withdrawal-induced apoptosis in CGNs. Cell death in primary cultures of rat CGNs was accompanied by chromatin condensation and activation of caspases-3, -6, and -9. Caspase-3 activity was also evaluated by cleavage of 120-kDa alpha-spectrin. Flavopiridol (1 microM) prevented caspase activation and abolished apoptotic features mediated by S/K withdrawal. Re-entry in the cell cycle is also involved in apoptotic neuronal cell death. Flavopiridol (1 microM) inhibited DNA synthesis as measured by BrdU incorporation, thus enhancing proliferating cell nuclear antigen expression. Serum/potassium (S/K) deprivation induced apoptotic cell death mediated by the activation of several kinases such as glycogen synthase kinase-3beta and CDK5, as well as the breakdown of p35 in the neurotoxic fragment p25; inactivation of myocyte enhancer factor-2 (MEF2) was also found. Pretreatment with flavopiridol prevented these biochemical and molecular alterations. Taken together, these findings suggest an apoptotic route in CGNs after S/K withdrawal mediated by the activation of several kinases involved in cell cycle deregulation and MEF2 inactivation. We propose that the antiapoptotic properties of flavopiridol are mediated through kinase pathway inhibition.
authors.affiliation: Unitat de Farmacologia i Farmacognòsia, Facultat de Farmàcia, Universitat de Barcelona, Nucli Universitari de Pedralbes, E-08028 Barcelona, Spain.
authors.forename: Ester
authors.initials: E
authors.lastname: Verdaguer
authors.forename: Elvira G
authors.initials: EG
authors.lastname: Jordà
authors.forename: Daniel
authors.initials: D
authors.lastname: Alvira
authors.forename: Andrés
authors.initials: A
authors.lastname: Jiménez
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Canudas
authors.forename: Jaume
authors.initials: J
authors.lastname: Folch
authors.forename: Victor
authors.initials: V
authors.lastname: Rimbau
authors.forename: Mercè
authors.initials: M
authors.lastname: Pallàs
authors.forename: Antoni
authors.initials: A
authors.lastname: Camins
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002453:Cell Cycle / Q000187:drug effects; D002531:Cerebellum / Q000502:physiology*; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D005419:Flavonoids / Q000494:pharmacology*; D005434:Flow Cytometry; D008959:Models, Neurological; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D010880:Piperidines / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D005419:Flavonoids; D010880:Piperidines; D047428:Protein Kinase Inhibitors; C077990:alvocidib; D018844:Cyclin-Dependent Kinases; D011188:Potassium