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PML is essential for multiple apoptotic pathways
Z G Wang1, D Ruggero, S Ronchetti
1Department of Human Genetics and Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, Graduate School of Medical Sciences, Cornell University, New York, New York 10021, USA.
Abstract:
The PML gene of acute promyelocytic leukaemia (APL) encodes a cell growth and tumour suppressor, however, the mechanisms by which PML suppresses tumorigenesis are poorly understood. We show here that Pml is required for Fas- and caspase-dependent DNA-damage-induced apoptosis. We also found that Pml is essential for induction of programmed cell death by Fas, tumour necrosis factor alpha (TNF), ceramide and type I and II interferons (IFNs). As a result, Pml-/- mice and cells are protected from the lethal effects of ionizing radiation and anti-Fas antibody. Pml is required for caspase 1 and caspase 3 activation upon exposure to these stimuli. The PML-RAR alpha fusion protein of APL renders haemopoietic progenitor cells resistant to Fas-, TNF- and IFN-induced apoptosis with a lack of caspase 3 activation, thus acting as a Pml dominant-negative product. These results demonstrate that Pml is a mediator of multiple apoptotic signals, and implicate inhibition of apoptosis in the pathogenesis of APL.
Insights
The PML gene is crucial for programmed cell death (apoptosis) and tumor suppression. Its absence protects mice from radiation and Fas antibody, highlighting its role in apoptosis and cancer.
Area of Science:
- Molecular Biology
- Cell Biology
- Cancer Biology
Background:
- The PML gene acts as a cell growth and tumor suppressor, but its precise mechanisms are unclear.
- Understanding PML's role in apoptosis is key to deciphering its tumor-suppressive functions.
Purpose of the Study:
- To elucidate the mechanisms by which PML suppresses tumorigenesis.
- To investigate PML's role in mediating apoptosis induced by various stimuli.
Main Methods:
- Utilized Pml-/- mice and cells to assess apoptosis induction.
- Examined caspase activation pathways in response to DNA damage, Fas, TNF, ceramide, and interferons.
Main Results:
- Pml is essential for Fas- and caspase-dependent apoptosis induced by DNA damage.
- Pml deficiency confers resistance to ionizing radiation and anti-Fas antibody.
- PML-RAR alpha fusion protein in APL inhibits apoptosis by blocking caspase 3 activation.
Conclusions:
- PML acts as a critical mediator for multiple apoptotic signaling pathways.
- Inhibition of PML-mediated apoptosis is implicated in the pathogenesis of acute promyelocytic leukemia (APL).