Article abstract
Nature Structural & Molecular Biology 15, 1094 - 1101 (2008)
Published online: 7 September 2008 | doi:10.1038/nsmb.1488
Inhibition of CED-3 zymogen activation and apoptosis in Caenorhabditis elegans by caspase homolog CSP-3
Xin Geng1, Yong Shi1, Akihisa Nakagawa1, Sawako Yoshina2, Shohei Mitani2, Yigong Shi3 & Ding Xue1
Abstract
Inhibitor of apoptosis (IAP) proteins have a crucial role in apoptosis, through negative regulation of caspases in species from fruitflies to mammals. In Caenorhabditis elegans, however, no IAP homolog or caspase inhibitor has been identified, calling into question how the cell-killing caspase CED-3 can be negatively regulated. Here we show that inactivation of the C. elegans csp-3 gene, which encodes a protein similar to the small subunit of the CED-3 caspase, causes cells that normally live to undergo apoptosis in a CED-3–dependent manner. Biochemical analysis reveals that CSP-3 associates with the large subunit of the CED-3 zymogen and inhibits zymogen autoactivation. However, CSP-3 does not block CED-3 activation induced by CED-4, nor does it inhibit the activity of the activated CED-3 protease. Therefore CSP-3 uses a previously unreported mechanism to protect cells from apoptosis.
- Department of Molecular, Cellular, and Developmental Biology, Campus Box 347, University of Colorado, Boulder, Colorado 80309, USA.
- Department of Physiology, Tokyo Women's Medical University, School of Medicine, and Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, 8-1, Kawada-cho, Shinjuku-ku, Tokyo, 162-8666, Japan.
- Department of Molecular Biology, Washington Road, Princeton University, Princeton, New Jersey 08544, USA.
Correspondence to: Ding Xue1 e-mail: ding.xue@colorado.edu
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