Human apurinic/apyrimidinic endonuclease (Ape1) and its N-terminal truncated form (AN34) are involved in DNA fragmentation during apoptosis.
We previously isolated a 34-kDa nuclease (AN34) from apoptotic human leukemia cells. Here, we identify AN34 as an N-terminally truncated form of human AP endonuclease (Ape1) lacking residues 1-35 (delta35-Ape1). Although Ape1 has hitherto been considered specific for damaged DNA (specific to AP site), recombinant AN34 (delta35-Ape1) possesses significant endonuclease activity on undamaged (normal) DNA and in chromatin. AN34 also displays enhanced 3'-5' exonuclease activity. Caspase-3 activates AN34 in a cell-free system, although caspase-3 cannot cleave Ape1 directly in vitro. We also found that Ape1 itself preferentially cleaves damaged chromatin DNA isolated from cells treated with apoptotic stimuli and that silencing of Ape1 expression decreases apoptotic DNA fragmentation in DFF40/CAD-deficient cells. Thus, we propose that AN34 and Ape1 participate in the process of chromatin fragmentation during apoptosis.
Yoshida
Akira
A
Laboratory of Molecular Pharmacology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892-4255, USA.
Urasaki
Yoshimasa
Y
Waltham
Mark
M
Bergman
Ann-Charlotte
AC
Pourquier
Philippe
P
Rothwell
Dominic G
DG
Inuzuka
Manabu
M
Weinstein
John N
JN
Ueda
Takanori
T
Appella
Ettore
E
Hickson
Ian D
ID
Pommier
Yves
Y
D000595:Amino Acid Sequence; D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000502:physiology; D053938:DNA Fragmentation; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D004706:Endodeoxyribonucleases / Q000032:analysis / Q000502:physiology*; D005092:Exonucleases / Q000378:metabolism; D020868:Gene Silencing; D008969:Molecular Sequence Data; D019311:Staurosporine / Q000494:pharmacology
D004706:Endodeoxyribonucleases; D005092:Exonucleases; C112751:apoptotic nuclease Mr 34,000; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D019311:Staurosporine