title: Excision of DNA loop domains as a common step in caspase-dependent and -independent types of neuronal cell death.
abstract: Treatment of rat cerebellar granule neurons with the phosphatase inhibitor, okadaic acid (OKA) or the excitatory neurotransmitter, L-glutamate, resulted in progressive cell death associated with apoptotic-like changes in nuclear morphology. The OKA-induced neurotoxicity was accompanied by the activation of caspase-3 (ICE-related cysteine protease) and the development of an oligonucleosomal DNA ladder, whereas neither activation of caspase-1, -2, -3, -5, or -9, nor internucleosomal DNA fragmentation accompanied L-glutamate-induced neurotoxicity. At the same time, both OKA and L-glutamate induced a similar pattern of nuclear DNA disintegration into high molecular weight (HMW)-DNA fragments of about 50-100 kb, which are widely believed to originate from the excision of DNA loop domains. Z-DEVD-fmk, a specific caspase-3 inhibitor, as well as a general caspase inhibitor, z-VAD-fmk, inhibited both the internucleosomal- and HMW-DNA fragmentation in OKA-treated neurons. However neither z-DEVD-fmk nor z-VAD-fmk had any obvious inhibitory effect on the formation of HMW-DNA fragments induced by L-glutamate. The results indicate that the formation of the HMW-DNA fragments in cerebellar granule neurons accompanies both caspase-dependent and -independent types of cell death, indicative of multiple mechanisms in the regulation of excision of DNA loop domains during neuronal cell death.
authors.affiliation: Department of Neuroscience and Neurology, University of Kuopio, Kuopio, Finland.
authors.forename: Z
authors.initials: Z
authors.lastname: Bezvenyuk
authors.forename: A
authors.initials: A
authors.lastname: Salminen
authors.forename: V
authors.initials: V
authors.lastname: Solovyan
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects* / Q000648:ultrastructure; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000502:physiology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D053938:DNA Fragmentation; D004789:Enzyme Activation; D018698:Glutamic Acid / Q000494:pharmacology*; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D009498:Neurotoxins / Q000494:pharmacology; D009707:Nucleosomes / Q000187:drug effects / Q000648:ultrastructure; D019319:Okadaic Acid / Q000494:pharmacology*; D009842:Oligopeptides / Q000494:pharmacology; D051381:Rats
chemical_list: D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D009498:Neurotoxins; D009707:Nucleosomes; D009842:Oligopeptides; C110772:benzoylcarbonyl-aspartyl-glutamyl-valyl-aspartyl-fluoromethyl ketone; D019319:Okadaic Acid; D018698:Glutamic Acid; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases