Related Experiment Videos
ASK1 mediates apoptotic cell death induced by genotoxic stress
1Laboratory of Biomedical Research, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Japan.
Abstract:
ASKI mediates apoptotic cell death induced by genotoxic stress Genotoxic stress-induced apoptosis is mediated by caspase family proteases as triggered by other stimuli. In this study, we found that the DNA-damaging agent cisplatin (cDDP) activated MAP kinase kinase kinase ASK1 and subsequent downstream subgroups of MAP kinase kinase, SEK1 (or MKK4) and MKK3/MKK6, which in turn activated c-Jun N-terminal kinase 1/stress-activated protein kinase (JNK1/SAPK) and p38 MAP kinase prior to caspase family protease activation and the onset of apoptosis in human ovarian carcinoma (OVCAR-3) and human kidney (293T) cells. As reported previously, benzyloxy carbonyl-Asp-CH2OC(O)-2, 6-dichlorobenzene (Z-Asp), a preferential inhibitor of caspase family proteases, blocked the apoptosis of OVCAR-3 cells induced by the genotoxic stress cDDP. Z-Asp, however, did not inhibit ASKI activation and the subsequent kinase cascades. Overexpression of kinase-negative ASK1 (K709R), which inhibited ASK1 activation and the downstream MKK3-p38 and MKK4-JNK1 pathways, also suppressed the caspase protease activation and apoptosis induced by cDDP. These results indicate that the ASK1 pathway is involved in genotoxic stress-induced apoptosis and mediates apoptosis at a step upstream of caspase protease activation.
Insights
Apoptosis induced by DNA damage involves the ASK1 (Apoptosis Signal-regulating Kinase 1) pathway. This pathway activates stress-activated protein kinases before caspase activation, indicating ASK1
Area of Science:
- Molecular Biology
- Cell Signaling
- Cancer Research
Background:
- Genotoxic stress triggers apoptosis via caspase proteases.
- The precise upstream regulators of this process remain under investigation.
Purpose of the Study:
- To elucidate the role of ASK1 (Apoptosis Signal-regulating Kinase 1) in genotoxic stress-induced apoptosis.
- To determine the position of ASK1 activation within the apoptotic signaling cascade.
Main Methods:
- Utilized cisplatin (cDDP) as a genotoxic stressor in human ovarian carcinoma (OVCAR-3) and human kidney (293T) cells.
- Investigated the activation of ASK1, downstream kinases (SEK1/MKK4, MKK3/MKK6, JNK1/SAPK, p38 MAP kinase), and caspase proteases.
- Employed caspase inhibitor Z-Asp and overexpressed kinase-negative ASK1 (K709R).
Main Results:
- Cisplatin activated the ASK1 pathway, leading to downstream kinase activation (JNK1/SAPK and p38 MAP kinase).
- Caspase inhibition (Z-Asp) blocked apoptosis but not ASK1 activation.
- Inhibition of ASK1 activation suppressed downstream pathways, caspase activation, and apoptosis.
Conclusions:
- The ASK1 pathway is integral to genotoxic stress-induced apoptosis.
- ASK1 mediates apoptosis upstream of caspase protease activation, highlighting its critical role in initiating the cell death program.