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FADD/MORT1, a signal transducer that can promote cell death or cell growth
1Walter and Eliza Hall Institute of Medical Research, Post Office Royal Melbourne Hospital, Vic., Australia. strasser@wehi.edu.au
Abstract:
FADD/MORT1 is a cytosolic adaptor protein which is critical for signalling from CD95 (Fas/APO-1) and certain other members of the tumour necrosis factor receptor (TNF-R) family (called 'death receptors'). Two protein interaction domains have been identified in FADD/MORT1. The C-terminal 'death domain' is needed for recruitment of FADD/MORT1 to ligated 'death receptors' and the N-terminal 'death effector domain' mediates oligomerisation and activation of caspase-8 zymogens. Caspase-8 activates other cysteine proteases by cleavage and this starts a proteolytic cascade which constitutes the 'point of no return' in apoptosis signalling. Experiments in mice lacking FADD/MORT1 function proved that this adaptor is required for CD95- and TNF-RI-transduced cell death but is dispensable for other pathways to apoptosis. Surprisingly, FADD/MORT1 is also essential for mitogen-induced proliferation of T-lymphocytes. Therapeutic activation of FADD/MORT1 function may be used to kill unwanted cells in cancer or autoimmunity and its suppression may help prevent cell death in certain degenerative disorders.
Insights
FADD/MORT1 protein is crucial for apoptosis signaling via death receptors, but also essential for T-lymphocyte proliferation. Its dual role offers therapeutic potential for cancer and autoimmune diseases.
Area of Science:
- Molecular Biology
- Immunology
- Cell Biology
Background:
- FADD/MORT1 is a cytosolic adaptor protein.
- It mediates signaling from death receptors like CD95 (Fas/APO-1) and TNF-R.
- FADD/MORT1 contains two key protein interaction domains: the C-terminal death domain and the N-terminal death effector domain.
Purpose of the Study:
- To elucidate the role of FADD/MORT1 in apoptosis and T-lymphocyte proliferation.
- To investigate the therapeutic potential of targeting FADD/MORT1 function.
Main Methods:
- Studies utilizing FADD/MORT1-deficient mice.
- Analysis of signaling pathways involving death receptors and caspase-8 activation.
Main Results:
- FADD/MORT1 is essential for CD95- and TNF-RI-mediated apoptosis.
- It is dispensable for other apoptosis pathways.
- FADD/MORT1 is surprisingly critical for T-lymphocyte proliferation induced by mitogens.
Conclusions:
- FADD/MORT1 plays a dual role in cell death and proliferation.
- Targeting FADD/MORT1 could be a therapeutic strategy for cancer, autoimmunity, and degenerative disorders.