TY - JOUR
T1 - Caspase-dependent apoptosis and -independent poly(ADP-ribose) polymerase cleavage induced by transforming growth factor β1
AU - Yang, Yanan
AU - Zhao, Sheng
AU - Song, Jianguo
N1 - Funding Information:
This work was supported by research grants from the Chinese Academy of Sciences (KSCX2-SW-203/KJ951-B1-608), the Virtual Research Institute of Aging of Nippon Boehringer Ingelheim, the Natural Sciences Foundation of China, and the research grants from “973” Project (#2002CB513000). We thank Dr. Jie Liu for AML-12 cells and Hehua Chen and Yiran Zhou for many helpful discussions and comments on this work.
PY - 2004/2
Y1 - 2004/2
N2 - Apoptosis is an important cell suicide program which involves the caspases activation and is implicated in physiological and pathological processes. Poly(ADP-ribose) polymerase (PARP) cleavage is often associated with apoptosis and has been served as one hallmark of apoptosis and caspase activation. In this study, we aimed to determine TGF-β1-induced apoptosis and to examine the involvement of caspases and its relationship with PARP cleavage. TGF-β1 induces strong apoptosis of AML-12 cells which can be detected by DNA fragmentation, FACS, and morphological assays. Z-VAD-fmk, a selective caspase inhibitor, partially inhibits the TGF-β1-induced apoptosis; but has no effect on TGF-β1-induced DNA fragmentation and PARP cleavage. However, BD-fmk, a broad-spectrum caspase inhibitor, completely suppresses TGF-β1-induced apoptosis, but unexpectedly does not inhibit TGF-β1-induced PARP cleavage. Furthermore, Z-VAD-fmk treatment is able to completely inhibit the daunorubicin-induced apoptosis in A-431 cells, but only slightly blocks the daunorubicin-induced PARP cleavage, whereas BD-fmk can inhibit both daunorubicin-induced apoptosis and PARP cleavage completely. In addition, we observed that both TGF-β1-induced apoptosis and PARP degradation in AML-12 cells can be completely blocked by inhibiting the protein synthesis with cycloheximide. These results demonstrate for the first time that TGF-β1-induced caspase-dependent apoptosis is associated with caspase-independent PARP cleavage that requires the TGF-β1-induced synthesis of new proteins. The results indicate that caspase-3 is not a major caspase involved in TGF-β1-induced apoptosis in AML-12 cells, and is not required for apoptosis-associated DNA fragmentation. The results also suggest that PARP cleavage may occur as an independent event that can be disassociated with cell apoptosis.
AB - Apoptosis is an important cell suicide program which involves the caspases activation and is implicated in physiological and pathological processes. Poly(ADP-ribose) polymerase (PARP) cleavage is often associated with apoptosis and has been served as one hallmark of apoptosis and caspase activation. In this study, we aimed to determine TGF-β1-induced apoptosis and to examine the involvement of caspases and its relationship with PARP cleavage. TGF-β1 induces strong apoptosis of AML-12 cells which can be detected by DNA fragmentation, FACS, and morphological assays. Z-VAD-fmk, a selective caspase inhibitor, partially inhibits the TGF-β1-induced apoptosis; but has no effect on TGF-β1-induced DNA fragmentation and PARP cleavage. However, BD-fmk, a broad-spectrum caspase inhibitor, completely suppresses TGF-β1-induced apoptosis, but unexpectedly does not inhibit TGF-β1-induced PARP cleavage. Furthermore, Z-VAD-fmk treatment is able to completely inhibit the daunorubicin-induced apoptosis in A-431 cells, but only slightly blocks the daunorubicin-induced PARP cleavage, whereas BD-fmk can inhibit both daunorubicin-induced apoptosis and PARP cleavage completely. In addition, we observed that both TGF-β1-induced apoptosis and PARP degradation in AML-12 cells can be completely blocked by inhibiting the protein synthesis with cycloheximide. These results demonstrate for the first time that TGF-β1-induced caspase-dependent apoptosis is associated with caspase-independent PARP cleavage that requires the TGF-β1-induced synthesis of new proteins. The results indicate that caspase-3 is not a major caspase involved in TGF-β1-induced apoptosis in AML-12 cells, and is not required for apoptosis-associated DNA fragmentation. The results also suggest that PARP cleavage may occur as an independent event that can be disassociated with cell apoptosis.
KW - Apoptosis
KW - Caspase
KW - Hepatocytes
KW - PARP
KW - TGF-β
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U2 - 10.1016/S1357-2725(03)00215-2
DO - 10.1016/S1357-2725(03)00215-2
M3 - Article
C2 - 14643888
AN - SCOPUS:0345276715
VL - 36
SP - 223
EP - 234
JO - International Journal of Biochemistry
JF - International Journal of Biochemistry
SN - 1357-2725
IS - 2
ER -