title: Human apurinic/apyrimidinic endonuclease (Ape1) and its N-terminal truncated form (AN34) are involved in DNA fragmentation during apoptosis.
abstract: 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.
authors.affiliation: Laboratory of Molecular Pharmacology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892-4255, USA.
authors.forename: Akira
authors.initials: A
authors.lastname: Yoshida
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Urasaki
authors.forename: Mark
authors.initials: M
authors.lastname: Waltham
authors.forename: Ann-Charlotte
authors.initials: AC
authors.lastname: Bergman
authors.forename: Philippe
authors.initials: P
authors.lastname: Pourquier
authors.forename: Dominic G
authors.initials: DG
authors.lastname: Rothwell
authors.forename: Manabu
authors.initials: M
authors.lastname: Inuzuka
authors.forename: John N
authors.initials: JN
authors.lastname: Weinstein
authors.forename: Takanori
authors.initials: T
authors.lastname: Ueda
authors.forename: Ettore
authors.initials: E
authors.lastname: Appella
authors.forename: Ian D
authors.initials: ID
authors.lastname: Hickson
authors.forename: Yves
authors.initials: Y
authors.lastname: Pommier
mesh_terms: 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
chemical_list: 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