Báo cáo khoa học: a-Fetoprotein positively regulates cytochrome c-mediated caspase activation and apoptosome complex formation

α-Fetoprotein Positively Regulates Cytochrome c-Mediated Caspase Activation and Apoptosome Complex Formation

Authors: Lidia Semenkova, Elena Dudich, Igor Dudich, Natalie Tokhtamisheva, Edward Tatulov, Yury Okruzhnov, Jesus Garcia-Foncillas, Juan-Antonio Palop-Cubillo, and Timo Korpela

Field: Biochemistry, Molecular Biology

Document Description: This study investigates the molecular mechanisms by which α-fetoprotein (AFP) mediates apoptosis in tumor cells. The research demonstrates that AFP treatment leads to the release of cytochrome c from mitochondria and synergistically enhances caspase activation in a cell-free system. AFP positively regulates the formation of the Apaf-1 apoptosome complex, promoting the recruitment and activation of caspases 3 and 9, and their subsequent release. Furthermore, AFP was found to negatively regulate the binding of cIAP-2 to caspases, thereby facilitating caspase activation. The findings suggest that AFP plays a crucial role in regulating the apoptotic pathway by modulating apoptosome complex formation and function.

Detailed Table of Contents:

• Introduction
• Materials and Methods
• AFP purification
• Cells
• Cytotoxicity assay
• Preparation of cell-free extracts
• In vitro caspase activation
• Fluorimetric assay of caspase activity
• Immunoprecipitation and immunoblotting analysis
• Assay of cyt-c release
• Direct protein-protein interaction assay
• Chromatographic analysis of the apoptosome assembly
• Results
• AFP induces release of mitochondrial cyt-c in HepG2 cells
• AFP synergistically enhances low-dose cyt-c-mediated caspase activation in cell-free cytosolic extracts
• AFP synergistically enhances cyt-c-mediated processing and activation of procaspases 9 and 3 in cell-free cytosolic extracts
• AFP induces caspase activation only in the presence of the all components of the apoptosome complex
• Depletion of cyt-c abrogates AFP-mediated caspase activation in cytosolic extracts
• Procaspase 9 is required for AFP-mediated caspase 3 activation
• AFP cannot induce activation of procaspase 9 in the absence of caspase 3
• AFP positively regulates cyt-c-mediated apoptosome complex formation in a cell-free system and release of active caspases from the complex
• Effect of AFP on the distribution of Apaf-1 and cIAP-2 proteins along the chromatographic pattern of the apoptosome assembly
• Interaction between caspase 9, caspase 3, c-IAP-2 and AFP
• Discussion
• Acknowledgements
• References