title: Formation of 50 kbp chromatin fragments in isolated liver nuclei is mediated by protease and endonuclease activation.
abstract: Isolated rat liver nuclei were incubated in the presence of divalent cations, and the mechanisms underlying the subsequent chromatin fragmentation were investigated. Either of the two cations, Ca2+ or Mg2+ was sufficient to produce chromatin fragments with sizes between 700 and 300 kbp. The formation of chromatin fragments of 50 kbp as well as the following internucleosomal DNA cleavage--which are characteristic of apoptosis--were markedly stimulated in the presence of Ca2+. Chromatin degradation to 50 kbp and smaller (oligonucleosome-size) fragments was prevented by inhibitors of endonucleases and serine proteases. We suggest a mechanism whereby the concerted activity of both proteases and endonucleases results in the widespread chromatin cleavage observed in cells undergoing apoptosis.
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Zhivotovsky
authors.forename: D
authors.initials: D
authors.lastname: Wade
authors.forename: A
authors.initials: A
authors.lastname: Gahm
authors.forename: S
authors.initials: S
authors.lastname: Orrenius
authors.forename: P
authors.initials: P
authors.lastname: Nicotera
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002458:Cell Fractionation; D002467:Cell Nucleus / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism*; D004249:DNA Damage; D004720:Endonucleases / Q000378:metabolism*; D010450:Endopeptidases / Q000378:metabolism*; D004789:Enzyme Activation; D008099:Liver / Q000378:metabolism*; D008297:Male; D051381:Rats; D017208:Rats, Wistar
chemical_list: D002843:Chromatin; D004720:Endonucleases; D010450:Endopeptidases; D002118:Calcium