Initiation of apoptosis by granzyme B requires direct cleavage of Bid, but not direct granzyme B-mediated caspase activation

Sutton, VR; Davis, JE; Cancilla, M; Johnstone, RW; Ruefli, AA; Sedelies, K; Browne, KA; Trapani, JA

Author(s): Sutton, VR; Davis, JE; Cancilla, M; Johnstone, RW; Ruefli, AA; Sedelies, K; Browne, KA; Trapani, JA;
Details: Publication Year 2000-11-20,Volume 192,Issue #10,Page 1403-1413
Journal Title: JOURNAL OF EXPERIMENTAL MEDICINE
Publication Type: Journal Article
Abstract: The essential upstream steps in granzyme B-mediated apoptosis remain undefined. Herein, we show that granzyme B triggers the mitochondrial apoptotic pathway through direct cleavage of Bid; however, cleavage of procaspases was stalled when mitochondrial disruption was blocked by Bcl-2. The sensitivity of granzyme B-resistant Bcl-2-overexpressing FDC-P1 cells was restored by coexpression of wild-type Bid, or Bid with a mutation of its caspase-8 cleavage site, and both types of Bid were cleaved. However, Bid with a mutated granzyme B cleavage site remained intact and did not restore apoptosis. Bid with a mutation preventing its interaction with Bcl-2 was cleaved but also failed to restore apoptosis. Rapid Bid cleavage by granzyme B (<2 min) was not delayed by Bcl-2, over-expression. These results clearly placed Bid cleavage upstream of mitochondrial Bcl-2. In granzyme B-treated Jurkat cells, endogenous Bid cleavage and loss of mitochondrial membrane depolarization occurred despite caspase inactivation with z-Val-Ala-Asp-fluoromethylketone or Asp-Glu-Val-Asp-fluoromethylketone. Initial partial processing of procaspase-3 and -8 was observed irrespective of Bcl-2 overexpression; however, later processing was completely abolished by Bcl-2. Overall, our results indicate that mitochondrial perturbation by Bid is necessary to achieve a lethal threshold of caspase activity and cell death due to granzyme B.
Publisher: ROCKEFELLER UNIV PRESS
Keywords: CYTOCHROME-C RELEASE; CYTOSOLIC DELIVERY; CELL-DEATH; PERFORIN; BCL-2; GENE; CYTOTOXICITY; PROTEASES; MITOCHONDRIA; INVOLVEMENT
Publisher's Version: https://doi.org/10.1084/jem.192.10.1403
Terms of Use/Rights Notice: Refer to copyright notice on published article.

Creation Date: 2000-11-20 12:00:00