Cathepsin B is activated as an executive protease in fetal rat alveolar type II cells exposed to hyperoxia.
10.3858/emm.2011.43.4.027
- Author:
Hyeon Soo LEE
1
;
Chun Ki KIM
Author Information
1. Department of Pediatrics, Kangwon National University Hospital School of Medicine, Chuncheon 200-947, Korea. premee@kangwon.ac.kr
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords:
caspase-3;
cathepsin B;
cell death;
fetal alveolar type II cell;
hyperoxia
- MeSH:
Animals;
Caspase 3;
Cathepsin B/*metabolism;
Cell Death;
Cell Hypoxia;
Enzyme Activation;
Female;
In Situ Nick-End Labeling;
L-Lactate Dehydrogenase/analysis;
Lung/metabolism;
Necrosis/metabolism;
Oxygen;
Pneumocytes/cytology/*metabolism;
Polymerase Chain Reaction;
Pregnancy;
Pulmonary Alveoli/cytology/embryology/*enzymology;
Rats;
Rats, Sprague-Dawley
- From:Experimental & Molecular Medicine
2011;43(4):223-229
- CountryRepublic of Korea
- Language:English
-
Abstract:
Alveolar type II cells are main target of hyperoxia-induced lung injury. The authors investigated whether lysosomal protease, cathepsin B (CB), is activated in fetal alveolar type II cells in the transitional period from the canalicular to saccular stages during 65%-hyperoxia and whether CB is related to fetal alveolar type II cell (FATIIC) death secondary to hyperoxia. FATIICs were isolated from embryonic day 19 rats and exposed to 65%-oxygen for 24 h and 36 h. The cells exposed to room air were used as controls. Cell cytotoxicity was assessed by lactate dehydrogenase-release and flow cytometry, and apoptosis was analyzed by TUNEL assay and flow cytometry. CB activity was assessed by colorimetric assay, qRT-PCR and western blots. 65%-hyperoxia induced FATIIC death via necrosis and apoptosis. Interestingly, caspase-3 activities were not enhanced in FATIICs during 65%-hyperoxia, whereas CB activities were greatly increased during 65%-hyperoxia in a time-dependent manner, and similar findings were observed with qRT-PCR and western blots. In addition, the preincubation of CB inhibitor prior to 65%-hyperoxia reduced FATIIC death significantly. Our studies suggest that CB activation secondary to hyperoxia might have a relevant role in executing the cell death program in FATIICs during the acute stage of 65%-hyperoxia.
