Ataxia telangiectasia mutated (ATM) is dispensable for endonuclease I-SceI-induced homologous recombination in mouse embryonic stem cells.
Ataxia telangiectasia mutated (ATM) is activated upon DNA double strand breaks (DSBs) and phosphorylates numerous DSB response proteins, including histone H2AX on serine 139 (Ser-139) to form γ-H2AX. Through interaction with MDC1, γ-H2AX promotes DSB repair by homologous recombination (HR). H2AX Ser-139 can also be phosphorylated by DNA-dependent protein kinase catalytic subunit and ataxia telangiectasia- and Rad3-related kinase. Thus, we tested whether ATM functions in HR, particularly that controlled by γ-H2AX, by comparing HR occurring at the euchromatic ROSA26 locus between mouse embryonic stem cells lacking either ATM, H2AX, or both. We show here that loss of ATM does not impair HR, including H2AX-dependent HR, but confers sensitivity to inhibition of poly(ADP-ribose) polymerases. Loss of ATM or H2AX has independent contributions to cellular sensitivity to ionizing radiation. The ATM-independent HR function of H2AX requires both Ser-139 phosphorylation and γ-H2AX/MDC1 interaction. Our data suggest that ATM is dispensable for HR, including that controlled by H2AX, in the context of euchromatin, excluding the implication of such an HR function in genomic instability, hypersensitivity to DNA damage, and poly(ADP-ribose) polymerase inhibition associated with ATM deficiency.
Department of Medicine, Harvard Medical School and Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA.
Emilie
E
Rass
Gurushankar
G
Chandramouly
Shan
S
Zha
Frederick W
FW
Alt
Anyong
A
Xie
D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects / Q000528:radiation effects; D051747:DNA-Activated Protein Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D053595:Embryonic Stem Cells / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D004706:Endodeoxyribonucleases / Q000378:metabolism; D006657:Histones / Q000235:genetics / Q000378:metabolism; D059765:Homologous Recombination; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects / Q000528:radiation effects; D010793:Phthalazines / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D022661:RNA, Untranslated; D011839:Radiation, Ionizing; D012694:Serine / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins; D002867:Chromones; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D004706:Endodeoxyribonucleases; D006657:Histones; D009025:Morpholines; D010793:Phthalazines; D010879:Piperazines; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D022661:RNA, Untranslated; D012694:Serine; D025521:Tumor Suppressor Proteins; C499693:8-dibenzothiophen-4-yl-2-morpholin-4-yl-chromen-4-one; C110853:Gt(ROSA)26Sor non-coding RNA, mouse; C576325:Atm protein, mouse; C531550:olaparib; C475961:gamma-H2AX protein, mouse