title: Roles of cathepsins in reperfusion-induced apoptosis in cultured astrocytes.
abstract: Astrocytic apoptosis may play a role in the central nervous system injury. We previously showed that reperfusion of cultured astrocytes with normal medium after exposure to hydrogen peroxide (H(2)O(2))-containing medium causes apoptosis. This study examines the involvement of the lysosomal enzymes cathepsins B and D in the astrocytic apoptosis. Reperfusion after exposure to H(2)O(2) caused a marked increase in caspase-3 and cathepsin D activities and a marked decrease in cathepsin B activity. Pepstatin A, an inhibitor of cathepsin D, and acetyl-L-aspartyl-L-methionyl-L-glutaminyl-L-aspart-1-aldehyde (Ac-DMQD-CHO), a specific inhibitor of caspase-3, blocked the H(2)O(2)-induced decrease in cell viability and DNA ladder formation in cultured rat astrocytes. The (L-3-trans-(propylcarbamoyl)oxirane-2-carbonyl)-L-isoleucyl-L-proline methyl ester (CA074 Me), a specific inhibitor of cathepsin B, did not affect the H(2)O(2)-induced cell injury. On the other hand, CA074 Me decreased cell viability with DNA ladder formation when cultured in the presence of Ac-DMQD-CHO. This caspase-independent apoptosis was attenuated by the addition of the cathepsin D inhibitor pepstatin A. Caspase-3 like activity was markedly inhibited by Ac-DMQD-CHO and partially by pepstatin A. Pepstatin A and CA074 Me inhibited cathepsin B and cathepsin D activities, respectively, in the presence and absence of Ac-DMQD-CHO. These results suggest that cathepsins B and D are involved in astrocytic apoptosis: cathepsin D acts as a death-inducing factor upstream of caspase-3 and the caspase-independent apoptosis is regulated antagonistically by cathepsins B and D.
authors.affiliation: Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, High Technology Research Center, Kobe Gakuin University, Kobe 651-2180, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Takuma
authors.forename: Makiko
authors.initials: M
authors.lastname: Kiriu
authors.forename: Koichi
authors.initials: K
authors.lastname: Mori
authors.forename: Eibai
authors.initials: E
authors.lastname: Lee
authors.forename: Riyo
authors.initials: R
authors.lastname: Enomoto
authors.forename: Akemichi
authors.initials: A
authors.lastname: Baba
authors.forename: Toshio
authors.initials: T
authors.lastname: Matsuda
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001253:Astrocytes / Q000473:pathology*; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002401:Cathepsin B / Q000037:antagonists & inhibitors / Q000502:physiology; D002402:Cathepsin D / Q000037:antagonists & inhibitors / Q000502:physiology; D002403:Cathepsins / Q000037:antagonists & inhibitors / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000633:toxicity; D010447:Peptide Hydrolases / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000473:pathology*
chemical_list: D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D004247:DNA; D006861:Hydrogen Peroxide; D002403:Cathepsins; D010447:Peptide Hydrolases; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D002401:Cathepsin B; D002402:Cathepsin D