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ASK1-p38 MAPK/JNK signaling cascade mediates anandamide-induced PC12 cell death
Krishna Pada Sarker1, Kamal Krishna Biswas, Munekazu Yamakuchi
1Department of Laboratory and Molecular Medicine, Faculty of Medicine, Kagoshima University, Kagoshima, Japan.
Abstract:
Anandamide is a neuroimmunoregulatory molecule that triggers apoptosis in a number of cell types including PC12 cells. Here, we investigated the molecular mechanisms underlying anandamide-induced cell death in PC12 cells. Anandamide treatment resulted in the activation of p38 mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase (JNK), and p44/42 MAPK in apoptosing cells. A selective p38 MAPK inhibitor, SB203580, or dn-JNK, JNK1(A-F) or SAPKbeta(K-R), blocked anandamide-induced cell death, whereas a specific inhibitor of MEK-1/2, U0126, had no effect, indicating that activation of p38 MAPK and JNK is critical in anandamide-induced cell death. An important role for apoptosis signal-regulating kinase 1 (ASK1) in this event was also demonstrated by the inhibition of p38 MAPK/JNK activation and death in cells overexpressing dn-ASK1, ASK1 (K709M). Conversely, the constitutively active ASK1, ASK1DeltaN, caused prolonged p38 MAPK/JNK activation and increased cell death. These indicate that ASK1 mediates anandamide-induced cell death via p38 MAPK and JNK activation. Here, we also found that activation of p38 MAPK/JNK is accompanied by cytochrome c release from the mitochondria and caspase activation (which can be inhibited by SB203580), suggesting that anandamide triggers a mitochondrial dependent apoptotic pathway. The caspase inhibitor, zVAD, and the mitochondrial pore opening inhibitor, cyclosporine A, blocked anandamide-induced cell death but not p38 MAPK/JNK activation, suggesting that activation of these kinases may occur upstream of mitochondrial associated events.
Insights
Anandamide triggers cell death in PC12 cells by activating p38 MAPK and JNK kinases. This process involves the apoptosis signal-regulating kinase 1 (ASK1) and mitochondrial pathways, leading to apoptosis.
Area of Science:
- Neuroimmunology
- Cell Biology
- Molecular Biology
Background:
- Anandamide is a neuroimmunoregulatory molecule.
- Anandamide induces apoptosis in various cell types, including PC12 cells.
Purpose of the Study:
- To investigate the molecular mechanisms of anandamide-induced cell death in PC12 cells.
- To identify key signaling pathways involved in anandamide-induced apoptosis.
Main Methods:
- PC12 cells were treated with anandamide.
- MAPK pathway activation was assessed using specific inhibitors and dominant-negative constructs.
- Apoptosis was evaluated by monitoring cell death, cytochrome c release, and caspase activation.
Main Results:
- Anandamide treatment activated p38 MAPK, JNK, and p44/42 MAPK.
- Inhibition of p38 MAPK and JNK, but not MEK-1/2, blocked anandamide-induced cell death.
- Apoptosis signal-regulating kinase 1 (ASK1) was found to mediate anandamide-induced cell death via p38 MAPK and JNK activation.
- Anandamide-induced cell death involved mitochondrial cytochrome c release and caspase activation, downstream of p38 MAPK/JNK activation.
Conclusions:
- Anandamide induces apoptosis in PC12 cells through the activation of p38 MAPK and JNK pathways.
- ASK1 plays a critical role in mediating anandamide-induced cell death.
- The process involves a mitochondrial-dependent apoptotic pathway initiated upstream by MAPK activation.