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Bcl-2 and Bcl-XL regulate proinflammatory caspase-1 activation by interaction with NALP1.

Bruey J.M., Bruey-Sedano N., Luciano F., Zhai D., Balpai R., Xu C., Kress C.L., Bailly-Maitre B., Li X., Osterman A., Matsuzawa S., Terskikh A.V., Faustin B., Reed J.C.

Caspases are intracellular proteases that cleave substrates involved in apoptosis or inflammation. In C. elegans, a paradigm for caspase regulation exists in which caspase CED-3 is activated by nucleotide-binding protein CED-4, which is suppressed by Bcl-2-family protein CED-9. We have identified a mammalian analog of this caspase-regulatory system in the NLR-family protein NALP1, a nucleotide-dependent activator of cytokine-processing protease caspase-1, which responds to bacterial ligand muramyl-dipeptide (MDP). Antiapoptotic proteins Bcl-2 and Bcl-X(L) bind and suppress NALP1, reducing caspase-1 activation and interleukin-1beta (IL-1beta) production. When exposed to MDP, Bcl-2-deficient macrophages exhibit more caspase-1 processing and IL-1beta production, whereas Bcl-2-overexpressing macrophages demonstrate less caspase-1 processing and IL-1beta production. The findings reveal an interaction of host defense and apoptosis machinery.

Cell 129:45-56(2007) [PubMed] [Europe PMC]