TY - JOUR
T1 - Cathepsin B contributes to TNF-α-mediated hepatocyte apoptosis by promoting mitochondrial release of cytochrome c
AU - Guicciardi, M. Eugenia
AU - Deussing, Jan
AU - Miyoshi, Hideyuki
AU - Bronk, Steven F.
AU - Svingen, Phyllis A.
AU - Peters, Christoph
AU - Kaufmann, Scott H.
AU - Gores, Gregory J.
PY - 2000
Y1 - 2000
N2 - TNF-α-induced apoptosis is thought to involve mediators from acidic vesicles. Cathepsin B (cat B), a lysosomal cysteine protease, has recently been implicated in apoptosis. To determine whether cat B contributes to TNF-α-induced apoptosis, we exposed mouse hepatocytes to the cytokine in vitro and in vivo. Isolated hepatocytes treated with TNF-α in the presence of the transcription inhibitor actinomycin D (AcD) accumulated cat B in their cytosol. Further experiments using cell-free systems indicated that caspase-8 caused release of active cat B from purified lysosomes and that cat B, in turn, increased cytosol-induced release of cytochrome c from mitochondria. Consistent with these observations, the ability of TNF-α/AcD to induce mitochondrial release of cytochrome c, caspase activation, and apoptosis of isolated hepatocytes was markedly diminished in cells from CatB(-/-) mice. Deletion of the CatB gene resulted in diminished liver injury and enhanced survival after treatment in vivo with TNF-α and an adenovirus construct expressing the IκB superrepressor. Collectively, these observations suggest that caspase-mediated release of cat B from lysosomes enhances mitochondrial release of cytochrome c and subsequent caspase activation in TNF-α-treated hepatocytes.
AB - TNF-α-induced apoptosis is thought to involve mediators from acidic vesicles. Cathepsin B (cat B), a lysosomal cysteine protease, has recently been implicated in apoptosis. To determine whether cat B contributes to TNF-α-induced apoptosis, we exposed mouse hepatocytes to the cytokine in vitro and in vivo. Isolated hepatocytes treated with TNF-α in the presence of the transcription inhibitor actinomycin D (AcD) accumulated cat B in their cytosol. Further experiments using cell-free systems indicated that caspase-8 caused release of active cat B from purified lysosomes and that cat B, in turn, increased cytosol-induced release of cytochrome c from mitochondria. Consistent with these observations, the ability of TNF-α/AcD to induce mitochondrial release of cytochrome c, caspase activation, and apoptosis of isolated hepatocytes was markedly diminished in cells from CatB(-/-) mice. Deletion of the CatB gene resulted in diminished liver injury and enhanced survival after treatment in vivo with TNF-α and an adenovirus construct expressing the IκB superrepressor. Collectively, these observations suggest that caspase-mediated release of cat B from lysosomes enhances mitochondrial release of cytochrome c and subsequent caspase activation in TNF-α-treated hepatocytes.
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U2 - 10.1172/JCI9914
DO - 10.1172/JCI9914
M3 - Article
C2 - 11067865
AN - SCOPUS:0033756474
SN - 0021-9738
VL - 106
SP - 1127
EP - 1137
JO - Journal of Clinical Investigation
JF - Journal of Clinical Investigation
IS - 9
ER -