The von Hippel-Lindau gene product inhibits renal cell apoptosis via Bcl-2-dependent pathways.
Previous studies have reported a protective role for the von Hippel-Lindau (VHL) gene products against pro-apoptotic cellular stresses, but the mechanisms remain unclear. In this study, we examined the role of VHL in renal cells subjected to chemical hypoxia, using four VHL-negative and two VHL-positive cell lines. VHL-negative renal carcinoma cells underwent apoptosis following chemical hypoxia (short-term glucose deprivation and antimycin treatment), as evidenced by morphologic changes and internucleosomal DNA cleavage. Reintroduction of VHL expression prevented this apoptosis. VHL-negative cells displayed a significant (greater than 5-fold) activation of caspase 9 and release of cytochrome c into the cytosol following chemical hypoxia. In contrast, VHL-positive cells showed minimal caspase 9 activation, and absence of cytochrome c release under the same conditions. Caspase 8 was only minimally activated in both VHL-negative and -positive cells. In addition, VHL-positive cells displayed a striking up-regulation of Bcl-2 expression (5-fold) following chemical hypoxia. Antisense oligonucleotides to Bcl-2 significantly down-regulated Bcl-2 protein expression in VHL-positive cells and rendered them sensitive to apoptosis. Overexpression of Bcl-2 in VHL-negative cells conferred resistance to apoptosis. Our results suggest that VHL protects renal cells from apoptosis via Bcl-2-dependent pathways.
Devarajan
P
P
Department of Pediatrics, Division of Pediatric Nephrology, Albert Einstein College of Medicine, Bronx, New York 10461, USA. pdevaraj@aecom.yu.edu
De Leon
M
M
Talasazan
F
F
Schoenfeld
A R
AR
Davidowitz
E J
EJ
Burk
R D
RD
D017209:Apoptosis / Q000502:physiology*; D001483:Base Sequence; D002292:Carcinoma, Renal Cell / Q000473:pathology; D015687:Cell Hypoxia; D003574:Cytochrome c Group / Q000378:metabolism; D017931:DNA Primers; D007668:Kidney / Q000166:cytology*; D007680:Kidney Neoplasms / Q000473:pathology; D008025:Ligases / Q000235:genetics / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology*; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D006623:von Hippel-Lindau Disease / Q000235:genetics*
D003574:Cytochrome c Group; D017931:DNA Primers; D019253:Proto-Oncogene Proteins c-bcl-2; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D008025:Ligases