Bid is upstream of lysosome-mediated caspase 2 activation in tumor necrosis factor α-induced hepatocyte apoptosis

M. Eugenia Guicciardi, Steven F. Bronk, Nathan W. Werneburg, Xiao-Ming Yin, Gregory J. Gores

Research output: Contribution to journalArticle

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Abstract

Background & Aims: During tumor necrosis factor α-mediated hepatocyte cytotoxicity, cathepsin B is released from lysosomes and contributes to apoptosis by indirectly promoting mitochondrial dysfunction. How this lysosomal pathway mediates mitochondrial dysfunction is unclear. Because Bcl-2 family proteins and caspase 2 have been implicated in proximal apoptosis-signaling pathways, we examined the role of these proteins in tumor necrosis factor α-induced lysosomal permeabilization and cathepsin B-mediated mitochondrial dysfunction. Methods: Studies were performed in primary hepatocytes from wild-type cathepsin B knockout, Bid knockout, and caspase 2 knockout mice and in the rat hepatoma cell line McArdle7777 by using tumor necrosis factor α/actinomycin D. Results: Studies in wild-type and Bid knockout hepatocytes showed that tumor necrosis factor α-mediated lysosomal permeabilization is Bid dependent. After tumor necrosis factor α/actinomycin D treatment, caspase 2 activity increased severalfold in wild-type hepatocytes, whereas minimal activity was observed in hepatocytes from cathepsin B knockout mice or in hepatoma cells treated with a cathepsin B inhibitor. In contrast, Bax was activated independently of cathepsin B. Pharmacological, genetic, or small interfering RNA-mediated inhibition of caspase 2 attenuated tumor necrosis factor α-mediated mitochondrial dysfunction, downstream caspase activation, and hepatocyte apoptosis. Conclusions: These data suggest that tumor necrosis factor α triggers Bid-dependent lysosomal permeabilization, followed by release of cathepsin B into the cytosol and activation of caspase 2. Caspase 2 then facilitates efficient mitochondrial cytochrome c release and apoptosis.

Original languageEnglish (US)
Pages (from-to)269-284
Number of pages16
JournalGastroenterology
Volume129
Issue number1
DOIs
StatePublished - Jul 2005
Externally publishedYes

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Caspase 2
Cathepsin B
Lysosomes
Hepatocytes
Tumor Necrosis Factor-alpha
Apoptosis
Dactinomycin
Knockout Mice
Hepatocellular Carcinoma
Caspases
Cytochromes c
Cytosol
Small Interfering RNA
Proteins
Pharmacology
Cell Line

ASJC Scopus subject areas

  • Gastroenterology

Cite this

Bid is upstream of lysosome-mediated caspase 2 activation in tumor necrosis factor α-induced hepatocyte apoptosis. / Guicciardi, M. Eugenia; Bronk, Steven F.; Werneburg, Nathan W.; Yin, Xiao-Ming; Gores, Gregory J.

In: Gastroenterology, Vol. 129, No. 1, 07.2005, p. 269-284.

Research output: Contribution to journalArticle

Guicciardi, M. Eugenia ; Bronk, Steven F. ; Werneburg, Nathan W. ; Yin, Xiao-Ming ; Gores, Gregory J. / Bid is upstream of lysosome-mediated caspase 2 activation in tumor necrosis factor α-induced hepatocyte apoptosis. In: Gastroenterology. 2005 ; Vol. 129, No. 1. pp. 269-284.
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abstract = "Background & Aims: During tumor necrosis factor α-mediated hepatocyte cytotoxicity, cathepsin B is released from lysosomes and contributes to apoptosis by indirectly promoting mitochondrial dysfunction. How this lysosomal pathway mediates mitochondrial dysfunction is unclear. Because Bcl-2 family proteins and caspase 2 have been implicated in proximal apoptosis-signaling pathways, we examined the role of these proteins in tumor necrosis factor α-induced lysosomal permeabilization and cathepsin B-mediated mitochondrial dysfunction. Methods: Studies were performed in primary hepatocytes from wild-type cathepsin B knockout, Bid knockout, and caspase 2 knockout mice and in the rat hepatoma cell line McArdle7777 by using tumor necrosis factor α/actinomycin D. Results: Studies in wild-type and Bid knockout hepatocytes showed that tumor necrosis factor α-mediated lysosomal permeabilization is Bid dependent. After tumor necrosis factor α/actinomycin D treatment, caspase 2 activity increased severalfold in wild-type hepatocytes, whereas minimal activity was observed in hepatocytes from cathepsin B knockout mice or in hepatoma cells treated with a cathepsin B inhibitor. In contrast, Bax was activated independently of cathepsin B. Pharmacological, genetic, or small interfering RNA-mediated inhibition of caspase 2 attenuated tumor necrosis factor α-mediated mitochondrial dysfunction, downstream caspase activation, and hepatocyte apoptosis. Conclusions: These data suggest that tumor necrosis factor α triggers Bid-dependent lysosomal permeabilization, followed by release of cathepsin B into the cytosol and activation of caspase 2. Caspase 2 then facilitates efficient mitochondrial cytochrome c release and apoptosis.",
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