Interleukin-1 beta-converting enzyme-like protease cleaves DNA-dependent protein kinase in cytotoxic T cell killing
AuthorSong, QZ; Burrows, SR; Smith, G; LeesMiller, SP; Kumar, S; Chan, DW; Trapani, JA; Alnemri, E; Litwack, G; Lu, H; ...
Source TitleJournal of Experimental Medicine
PublisherROCKEFELLER UNIV PRESS
University of Melbourne Author/sTrapani, Joseph
AffiliationSir Peter MacCallum Department of Oncology
Document TypeJournal Article
CitationsSong, Q. Z., Burrows, S. R., Smith, G., LeesMiller, S. P., Kumar, S., Chan, D. W., Trapani, J. A., Alnemri, E., Litwack, G., Lu, H., Moss, D. J., Jackson, S. & Lavin, M. F. (1996). Interleukin-1 beta-converting enzyme-like protease cleaves DNA-dependent protein kinase in cytotoxic T cell killing. JOURNAL OF EXPERIMENTAL MEDICINE, 184 (2), pp.619-626. https://doi.org/10.1084/jem.184.2.619.
Access StatusOpen Access
Cytotoxic T cells (CTL) represent the major defense mechanism against the spread of virus infection. It is believed that the pore-forming protein, perforin, facilitates the entry of a series of serine proteases (particularly granzyme B) into the target cell which ultimately leads to DNA fragmentation and apoptosis. We demonstrate here that during CTL-mediated cytolysis the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), an enzyme implicated in the repair of double strand breaks in DNA, is specifically cleaved by an interleukin (IL)-1 beta-converting enzyme (ICE)-like protease. A serine protease inhibitor, 3,4-dichloroisocoumarin (DCl), which is known to block granzyme B activity, inhibited CTL-induced apoptosis and prevented the degradation of DNA-PKcs in cells but failed to prevent the degradation of purified DNA-PKcs by CTL extracts. However, Tyr-Val-Ala-Asp-CH2Cl (YVAD-CMK) and other cysteine protease inhibitors prevented the degradation of purified DNA-PKcs by CTL extracts. Furthermore, incubation of DNA-PKcs with granzyme B did not produce the same cleavage pattern observed in cells undergoing apoptosis and when this substrate was incubated with either CTL extracts or the ICE-like protease, CPP32. Sequence analysis revealed that the cleavage site in DNA-PKcs during CTL killing was the same as that when this substrate was exposed to CPP32. This study demonstrates for the first time that the cleavage of DNA-PKcs in this intact cell system is exclusively due to an ICE-like protease.
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