Cyclin-dependent protein kinase 2 activity is required for mitochondrial translocation of Bax and disruption of mitochondrial transmembrane potential during etoposide-induced apoptosis.
Previous studies have suggested that upregulation of Cyclin A-dependent protein kinase 2 (Cdk2) activity is an essential event in apoptotic progression and the mitochondrial permeability transition in human cancer cells. Here, we show that upregulated Cyclin A/Cdk2 activity precedes the proteolytic cleavage of PARP and is correlated with the mitochondrial translocation of Bax and the loss of mitochondrial transmembrane potential (Deltapsim) during etoposide-induced apoptosis in human cervical adenocarcinoma (HeLa) cells. Etoposide-induced apoptotic cell death is efficiently prevented in cells that overexpress a dominant negative mutant of Cdk2 (Cdk2-dn) or p21(WAF1/CIP1), a specific Cdk inhibitor. Conversely, apoptotic cell death is promoted in Cyclin A-expressing cells. Disruption of the mitochondrial transmembrane potential in etoposide-induced cells is prevented in cells that overexpress Cdk2-dn or p21(WAF1/CIP1), while this transition is prominently promoted in Cyclin A-expressing cells. We screened for mitochondrial Cdk2 targets in the etoposide-induced cells and found that the mitochondrial level of Bax is elevated by more than three fold in etoposide-treated cells and this elevation is effectively prevented in cells expressing Cdk2-dn under the same conditions. Thus, we suggest that Cdk2 activity is involved in the mitochondrial translocation of Bax, which plays an important role in the mitochondrial membrane permeability transition during apoptotic progression.
Choi
Joon-Seok
JS
Division of Pharmaceutical Biosciences, College of Pharmacy and The Research Institute for Pharmaceutical Sciences, Seoul National University, Seoul, 151-742, Korea.
Shin
Soona
S
Jin
Ying Hua
YH
Yim
Hyungshin
H
Koo
Kyo-Tan
KT
Chun
Kwang-Hoon
KH
Oh
You-Take
YT
Lee
Won Hee
WH
Lee
Seung-Ki
SK
D017209:Apoptosis; D002460:Cell Line; D019925:Cyclin A / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2 / Q000378:metabolism*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism*; D005047:Etoposide / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism*; D010539:Permeability; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism*
D019925:Cyclin A; D050759:Cyclin-Dependent Kinase Inhibitor p21; D051028:bcl-2-Associated X Protein; D005047:Etoposide; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2