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Multi‐step DNA cleavage in rat liver nuclei is inhibited by thiol reactive agents
Author(s) -
Cain Kelvin,
Inayat-Hussain Salmaan H.,
Kokileva Ludmilla,
Cohen Gerald M.
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)01436-5
Subject(s) - cleavage (geology) , dithiothreitol , dna , thiol , microbiology and biotechnology , chemistry , dna fragmentation , endonuclease , fragmentation (computing) , biochemistry , serine protease , enzyme , protease , biology , apoptosis , programmed cell death , paleontology , ecology , fracture (geology)
DNA fragmentation in isolated rat liver nuclei is a Mg 2+ ‐dependent, multi‐step process which is potentiated by Ca 2+ and cleaves the DNA into ≥700, 200–300 and 30–50 kilobase pair (kbp) fragments, prior to internucleosomal cleavage by Ca 2+ /Mg 2+ ‐dependent endonuclease(s). We now show that Cd 2+ , Hg 2+ , dichloroisocoumarin (DCI, a serine protease inhibitor) and N ‐ethylmaleimide (NEM) block both Mg 2+ and Ca 2+ /Mg 2+ ‐dependent processes. Inhibition of DNA cleavage produced an increase in the size of the DNA fragments, from mono‐/oligonucleosomes to 30–50, 200–300, ≥700 kbp and finally to intact DNA. NEM and DCI inhibition was blocked by dithiothreitol, and it is proposed that a critical thiol(s) is involved in the DNA cleavage reactions which are a feature of the apoptotic process.