Related Experiment Videos
Differentiation-dependent sensitivity to apoptogenic factors in PC12 cells
Sheela Vyas1, Philippe Juin, David Hancock
1INSERM U497, Ecole Normale Supérieure, 46, rue d'Ulm, Paris 75005, France. vyas@wotan.ens.fr
The Journal of Biological Chemistry
|May 11, 2004
Summary
Differentiated PC12 cells resist apoptosis via mitochondrial pathways, unlike undifferentiated cells. Bcl-2 and Akt protect against cytochrome c release and caspase activation, with differentiation enhancing this resistance.
Area of Science:
- Cell Biology
- Molecular Biology
- Neuroscience
Background:
- PC12 cells are a model for neuronal differentiation and survival.
- Trophic factor withdrawal triggers apoptosis through the mitochondrial pathway.
- The roles of Bcl-2, Akt, and Inhibitors of Apoptosis Proteins (IAPs) in this process are complex.
Purpose of the Study:
- To investigate the mitochondrial cell death pathway in differentiated and undifferentiated PC12 cells after trophic factor withdrawal.
- To determine the protective mechanisms of Bcl-2 and Akt in both cell states.
- To elucidate the role of IAPs in differentiation-dependent apoptosis resistance.
Main Methods:
- PC12 cells were differentiated using nerve growth factor (NGF)/dibutyryl cyclic AMP (Bt(2)cAMP).
- Trophic factors were withdrawn to induce cell death.
- Mitochondrial factors (holocytochrome c, Smac/DIABLO, Omi/HtrA2) release was assessed.
- Expression and function of Bcl-2, Akt, caspases, and IAPs were analyzed.
- Apoptosis was induced by microinjected cytochrome c and Smac/DIABLO.
Main Results:
- Trophic factor withdrawal rapidly released mitochondrial apoptogenic factors in both cell types.
- Bcl-2 and Akt inhibited factor release and downstream caspase-9 activation, with greater efficacy in differentiated cells.
- Differentiated cells showed resistance to exogenous cytochrome c, while undifferentiated cells were sensitive.
- IAP regulation, including c-IAP-2 upregulation and X-linked IAP downregulation, correlated with differentiation and cell death.
- Overexpression of X-linked IAP conferred resistance to cytochrome c in undifferentiated cells.
Conclusions:
- Differentiation confers resistance to apoptosis by regulating the mitochondrial pathway at multiple levels.
- Bcl-2 and Akt provide protection against both cytochrome c release and downstream caspase activation in differentiated cells.
- The differentiation program involves altered expression and function of IAPs, contributing to apoptosis resistance.