HSP72 inhibits apoptosis-inducing factor release in ATP-depleted renal epithelial cells

• Published in: American Journal of Physiology: Cell Physiology 2003-12, Vol.285 (6), p.C1483-C1493
• Main Authors: Ruchalski, Kathleen, Mao, Haiping, Singh, Satish K, Wang, Yihan, Mosser, Dick D, Li, Fanghong, Schwartz, John H, Borkan, Steven C
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - deficiency; Animals; Apoptosis - physiology; Apoptosis Inducing Factor; Cell Nucleus - metabolism; DNA Fragmentation - physiology; Epithelial Cells - drug effects; Epithelial Cells - pathology; Epithelial Cells - physiology; Flavoproteins - metabolism; Heat Stress Disorders - physiopathology; Heat-Shock Proteins - metabolism; Heat-Shock Response - physiology; HSP72 Heat-Shock Proteins; Immunoblotting; Immunohistochemistry; Kidney - cytology; Kidney - physiology; Membrane Proteins - metabolism; Microscopy, Confocal; Mitochondria - metabolism; Mitochondria - pathology; Opossums; Precipitin Tests
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.00049.2003

1 Renal Section and 3 Section of Gastroenterology, Department of Medicine, Boston Medical Center, Boston University, Boston, Massachusetts 02118-2518; 2 Department of Nephrology, The First Affiliated Hospital, Zhongshan University, GuangZhou, China 510080; 4 Department of Pathology, Tufts University and New England Medical Center, Boston, Massachusetts 02111-1533; and 5 Department of Molecular Biology and Genetics, University of Guelph, Ontario, Canada N1G 2W1 Submitted 4 February 2003 ; accepted in final form 31 July 2003 Inhibition of the mitochondrial release and nuclear translocation of apoptosis-inducing factor (AIF) by heat stress protein (HSP)72 may ameliorate apoptosis in renal epithelial cells exposed to a metabolic inhibitor. To evaluate this hypothesis, cells were transiently exposed to 5 mM sodium cyanide in the absence of medium glucose, a maneuver known to induce apoptosis. ATP depletion for 1-2 h resulted in the progressive accumulation of mitochondrial AIF in the cytosol of samples obtained by selectively permeabilizing the plasma membrane with digitonin. During recovery from ATP depletion, time-dependent nuclear AIF accumulation (but not cytochrome c , an F 0 F 1 ATP synthase subunit, or talin) was observed in isolated nuclei. Nuclear AIF accumulation was associated with peripheral chromatin condensation and DNA degradation. Prior heat stress (HS) significantly reduced AIF leakage into the cytosol, decreased nuclear accumulation of AIF, and inhibited DNA degradation. HS also increased the interaction between AIF and HSP72 detected by immunoprecipitation. In ATP depleted cells, selective overexpression of human HSP72 reduced the leakage of mitochondrial AIF in a dose-dependent manner ( r = 0.997). This study suggests that mitochondrial membrane injury and subsequent AIF release contribute to nuclear injury and apoptosis in ATP-depleted renal cells. HSP72, an antiapoptotic protein, inhibits cell injury in part by preventing mitochondrial AIF release and perhaps by decreasing its nuclear accumulation. heat stress; adenovirus; metabolic inhibitors; heat stress protein 60; DNA degradation Address for reprint requests and other correspondence: S. C. Borkan, Evans Biomedical Research Center, Renal Section, Rm. 547, 650 Albany St., Boston, MA 02118-2518 (E-mail: sborkan{at}bu.edu ).