On the use of Zn2+ to discriminate endonucleases activated during apoptosis.
One approach to discriminate among specific DNases in apoptosis is to use inhibitors specific for each endonuclease. Zn2+ is known to inhibit Ca(2+)- and Mg(2+)-dependent endonuclease enzymatic activities during apoptosis. Acidic DNases were thought to be insensitive to Zn2+. In this paper, we analyse the effects of Zn2+ on activity of DNase II, either purified or in nuclei from lens fiber cells. These cells follow a physiological nuclear degeneration with DNase II accumulation in their nuclei. We show that Zn2+ is able to inhibit also this acidic endonuclease at a concentration of 1-6 mM. At a higher concentration of Zn2+, DNA is extensively degraded during the assay, masking the inhibition of the enzyme. This DNA degradation in the presence of Zn2+ has led to an overestimation of the activity of DNase II in studies of apoptosis. Hence, Zn2+ cannot be used to specifically identify one endonuclease among the different DNases involved in nuclear degradation during programmed cell death.
Torriglia
A
A
Développement, pathologie et vieillissement de la rétine, U450 INSERM-CNRS, Association Claude Bernard, Paris, France.
Chaudun
E
E
Courtois
Y
Y
Counis
M F
MF
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002417:Cattle; D002642:Chick Embryo; D053938:DNA Fragmentation / Q000187:drug effects; D004706:Endodeoxyribonucleases / Q000037:antagonists & inhibitors / Q000187:drug effects* / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D004926:Escherichia coli; D007904:Lens Cortex, Crystalline / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D013552:Swine; D015032:Zinc / Q000494:pharmacology*
D004706:Endodeoxyribonucleases; C029367:calcium magnesium dependent endodeoxyribonuclease; C019329:deoxyribonuclease II; D015032:Zinc