Evidence that non-caspase proteases are required for chromatin degradation during apoptosis.

Published

Journal Article

Chromatin degradation into oligonucleosomal and approximately 30-50 Kb fragments is a hallmark of apoptosis. Crude nuclear extract from apoptotic rat thymocytes is able to recapitulate both types of DNA fragmentation in an assay using HeLa cell nuclei as an exogenous substrate. Using size exclusion chromatography we have identified a novel activity (approximately 260 Kd) that produces only approximately 30-50 Kb DNA fragments, and a 25 Kd activity that generates both approximately 30-50 Kb and oligonucleosomal fragments. Both activities produced DNA fragments with 3'-OH termini, are dependent on Ca2+ and Mg2+ and are inhibited by N-ethyl-maleimide, sodium tetrathionate, aurintricarboxylic acid and sodium chloride, similar to other nucleases implicated in apoptosis. These activities were inhibited by the serine protease inhibitors N-tosyl-L-phenylalanine chloromethyl ketone and N alpha-p-tosyl-L-lysine chloromethyl ketone, but not by the serine protease inhibitor diisopropyl fluorophosphate, or by calpain inhibitors I or II, or the capsase inhibitors Ac-Asp-Glu-Val-Asp-aldehyde, Ac-Tyr-Val-Ala-Asp-aldehyde, or Z-Val-Ala-Asp-fluoromethyl ketone. Both activities were insensitive to protease inhibitors when extracts were incubated with naked linear DNA, indicating the presence of both nuclease and protease activities in the preparation. Together, these observations suggest the involvement of non-caspase proteases in apoptosis which perhaps function by altering chromatin substructure and exposing it to nucleolytic attack.

Full Text

Duke Authors

Cited Authors

  • Hughes, FM; Evans-Storms, RB; Cidlowski, JA

Published Date

  • December 1998

Published In

Volume / Issue

  • 5 / 12

Start / End Page

  • 1017 - 1027

PubMed ID

  • 9894608

Pubmed Central ID

  • 9894608

International Standard Serial Number (ISSN)

  • 1350-9047

Digital Object Identifier (DOI)

  • 10.1038/sj.cdd.4400418

Language

  • eng

Conference Location

  • England