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Internucleosomal DNA cleavage in apoptotic WEHI 231 cells is mediated by a chymotrypsin‐like protease
Author(s) -
Murn Jernej,
Urleb Uros,
MlinaricRascan Irena
Publication year - 2004
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1111/j.1365-2443.2004.00794.x
Subject(s) - proteases , apoptosis , biology , dna fragmentation , caspase , protease , chymotrypsin , serine protease , poly adp ribose polymerase , serine , proteolysis , serine proteinase inhibitors , microbiology and biotechnology , cytochrome c , biochemistry , programmed cell death , trypsin , enzyme , polymerase
Although several lines of evidence support a role for serine proteases in apoptosis, little is known about the mechanisms involved. In the present study, we have examined the apoptosis‐inducing potential and dissected the death‐signalling pathways of N‐tosyl‐L‐phenylalanine chloromethyl ketone (TPCK) and N‐tosyl‐L‐lysine chloromethyl ketone (TLCK), inhibitors of chymotrypsin‐ and trypsin‐like proteases, respectively. Our results designate two distinct roles for serine proteases. Firstly, we show that both inhibitors induce biochemical and morphological characteristics of apoptosis, including proteolysis of poly(ADP‐ribose) polymerase 1 (PARP‐1) and inhibitor of caspase‐activated DNase (ICAD), as well as mitochondrial dysfunction, and that their action is abrogated by the caspase inhibitor benzyloxycarbonyl‐Val‐Ala‐Asp.fluoromethylketone (z‐VAD.fmk). These results suggest that inhibition of anti‐apoptotic serine proteases governs the onset of the caspase‐dependant apoptotic cascade. Secondly, we also demonstrate the involvement of a serine protease in the terminal stage of apoptosis. We showed that chymotrypsin‐like protease activity is required for internucleosomal DNA fragmentation in apoptotic cells. Hence, DNA fragmentation is abrogated in TPCK‐pre‐treated WEHI 231 cells undergoing apoptosis triggered either by anti‐IgM or TLCK. These results indicate that internucleosomal DNA cleavage in apoptotic cells is mediated by a chymotrypsin‐like protease.