Abstract
The role of proteinases in renal proximal tubule (RPT) cellular death was examined using specific inhibitors of proteinases. Rabbit RPT suspensions were incubated with antimycin A for 1 h or tetrafluoroethyl-L- cysteine (TFEC) for 4 h in the absence or presence of the specific cysteine proteinase inhibitor L-trans-epoxysuccinyl-leucylamido(4-guanidino)butane (E-64), the serine proteinase inhibitors N-p-tosyl-L-lysine chloromethyl ketone (TLCK) or 3,4-dichloroisocoumarin (DCS), the serine and cysteine proteinase inhibitors leupeptin or antipain, or the aspartic proteinase inhibitor pepstatin. E-64 and pepstatin decreased lactate dehydrogenase (LDH) release, a marker of cell death, from RPT exposed either to antimycin A or TFEC, TLCK, DCS, leupeptin, or antipain did not decrease antimycin A- or TFEC induced cell death. Bromohydroquinone- or t-butylhydroperoxide- induced cell death was not decreased by any of the proteinase inhibitors. Loss of lysosomal membrane potential, indicated by neutral red release, occurred prior to the onset of antimycin A-induced cell death. Extensive inhibition of lysosomal cathepsins B and L by E-64 was correlated with cytoprotection. However, E-64 was only protective after some cell death had occurred. These results suggest that lysosomal cysteine and aspartic proteinases, but not serine proteinases, play a role in RPT cell death induced by antimycin A or TFEC. The observation that E-64 was only protective after some cell death had occurred suggests that lysosomal cathepsins are released from dying cells and subsequently attack the remaining viable cells.
Original language | English (US) |
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Pages (from-to) | 319-332 |
Number of pages | 14 |
Journal | Journal of Toxicology and Environmental Health |
Volume | 48 |
Issue number | 4 |
DOIs | |
State | Published - 1996 |
Externally published | Yes |
ASJC Scopus subject areas
- Toxicology
- Pollution