Suppression of apoptosis by cyclophilin D via stabilization of hexokinase II mitochondrial binding in cancer cells.
The permeability transition pore is involved in the mitochondrial pathway of apoptosis. Cyclophilin D, a pore component, has catalytic activity as a peptidyl prolyl cis, trans-isomerase (PPIase), which is essential to the pore opening. It has been reported that cyclophilin D overexpression suppresses apoptosis in cancer cells. To clarify the mechanism of this effect, we generated glioma cells overexpressing wild-type or a PPIase-deficient mutant of cyclophilin D. Interestingly, we found that the PPIase-dependent apoptosis suppression by cyclophilin D correlated with the amounts of mitochondrial-bound hexokinase II, which has anti-apoptotic activity. Inactivation of endogenous cyclophilin D by small interference RNA or a cyclophilin inhibitor was found to release hexokinase II from mitochondria and to enhance Bax-mediated apoptosis. The anti-apoptotic effects of cyclophilin D were canceled out by the detachment of hexokinase II from mitochondria, demonstrating that mitochondrial binding of hexokinase II is essential to the apoptosis suppression by cyclophilin D. Furthermore, cyclophilin D dysfunction appears to abrogate hexokinase II-mediated apoptosis suppression, indicating that cyclophilin D is required for the anti-apoptotic activity of hexokinase II. Based on the above, we propose here that cyclophilin D suppresses apoptotic cell death via a mitochondrial hexokinase II-dependent mechanism in cancer cells.
Antibiotics Laboratory, Discovery Research Institute, RIKEN, Hirosawa 2-1, Saitama 351-0198, Japan.
Kiyotaka
K
Machida
Yoshihiro
Y
Ohta
Hiroyuki
H
Osada
D000818:Animals; D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D000081406:Peptidyl-Prolyl Isomerase F; D021983:Cyclophilins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D006367:HeLa Cells; D006593:Hexokinase / Q000378:metabolism*; D006801:Humans; D008928:Mitochondria / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D034622:RNA Interference; D051381:Rats; D051028:bcl-2-Associated X Protein / Q000378:metabolism
D000081406:Peptidyl-Prolyl Isomerase F; D051028:bcl-2-Associated X Protein; D006593:Hexokinase; C505407:CASP3 protein, human; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D021983:Cyclophilins