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Proteolytic cleavage of epidermal growth factor receptor by caspases
1Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang 790-784, South Korea.
Abstract:
Apoptotic proteases cleave and inactivate survival signaling molecules such as Akt/PKB, phospholipase C (PLC)-gamma1, and Bcl-2. We have found that treatment of A431 cells with tumor necrosis factor-alpha in the presence of cycloheximide resulted in the cleavage of epidermal growth factor receptor (EGFR) as well as the activation of caspase-3. Among various caspases, caspase-1, caspase-3 and caspase-7 were most potent in the cleavage of EGFR in vitro. Proteolytic cleavage of EGFR was inhibited by both YVAD-cmk and DEVD-fmk in vitro. We also investigated the effect of caspase-dependent cleavage of EGFR upon the mediation of signals to downstream signaling molecules such as PLC-gamma1. Cleavage of EGFR by caspase-3 significantly impaired the tyrosine phosphorylation of PLC-gamma1 in vitro. Given these results, we suggest that apoptotic protease specifically cleaves and inactivates EGFR, which plays crucial roles in anti-apoptotic signaling, to abrogate the activation of EGFR-dependent downstream survival signaling molecules.
Insights
Apoptotic proteases, specifically caspases, cleave and inactivate the epidermal growth factor receptor (EGFR). This process disrupts survival signaling pathways, including those involving phospholipase C (PLC)-gamma1, during apoptosis.
Area of Science:
- Cellular Biology
- Molecular Biology
- Biochemistry
Background:
- Apoptotic proteases are key mediators of programmed cell death.
- Survival signaling molecules like Akt/PKB, PLC-gamma1, and Bcl-2 are typically inactivated during apoptosis.
- The role of apoptotic proteases in cleaving cell surface receptors, such as EGFR, is not fully understood.
Purpose of the Study:
- To investigate the cleavage of epidermal growth factor receptor (EGFR) by apoptotic proteases.
- To identify specific caspases responsible for EGFR cleavage.
- To determine the functional consequences of EGFR cleavage on downstream survival signaling pathways.
Main Methods:
- Treatment of A431 cells with tumor necrosis factor-alpha and cycloheximide.
- In vitro cleavage assays using purified caspases (caspase-1, -3, -7) and EGFR.
- Inhibition studies using caspase inhibitors (YVAD-cmk, DEVD-fmk).
- Assessment of phospholipase C (PLC)-gamma1 tyrosine phosphorylation after EGFR cleavage.
Main Results:
- Treatment of A431 cells induced EGFR cleavage and caspase-3 activation.
- Caspase-1, -3, and -7 were identified as potent inducers of EGFR cleavage in vitro.
- Proteolytic cleavage of EGFR was inhibited by specific caspase inhibitors.
- Caspase-3-mediated cleavage of EGFR impaired the tyrosine phosphorylation of PLC-gamma1.
Conclusions:
- Apoptotic proteases, particularly caspases, directly cleave and inactivate EGFR.
- EGFR cleavage by caspases abrogates the activation of EGFR-dependent downstream survival signaling.
- This mechanism contributes to the inactivation of anti-apoptotic signaling during programmed cell death.