DNA fragmentation into 200-250 and/or 30-50 kilobase pair fragments in rat liver nuclei is stimulated by Mg2+ alone and Ca2+/Mg2+ but not by Ca2+ alone.
Internucleosomal cleavage of DNA has often been regarded as the biochemical hallmark of apoptosis. We now demonstrate in isolated rat liver nuclei that DNA is initially cleaved into > or = 700, 200-250 kbp and 30-50 kbp fragments via a multi-step process, which is activated by Mg2+ and Mg2+(+)Ca2+ but not by Ca2+ alone. The subsequent internucleosomal cleavage requires both cations. These findings demonstrate that a key event in the apoptotic process is the fragmentation of DNA into large kbp fragments by either a Mg(2+)-dependent process (which can be potentiated by Ca2+) and/or by a Ca2+/Mg2+ activated endonuclease(s).
Cain
K
K
MRC Toxicology Unit, University of Leicester, UK.
Inayat-Hussain
S H
SH
Wolfe
J T
JT
Cohen
G M
GM
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002118:Calcium / Q000494:pharmacology; D002413:Cations, Divalent / Q000494:pharmacology*; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects / Q000502:physiology*; D004357:Drug Synergism; D005434:Flow Cytometry; D008099:Liver / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D051381:Rats; D013997:Time Factors
D002413:Cations, Divalent; D008274:Magnesium; D002118:Calcium