The isoflavonoids genistein and quercetin activate different stress signaling pathways as shown by analysis of site-specific phosphorylation of ATM, p53 and histone H2AX.
The ataxia-telangiectasia mutated (ATM) protein kinase is activated in response to ionizing radiation (IR) and activates downstream DNA-damage signaling pathways. Although the role of ATM in the cellular response to ionizing radiation has been well characterized, its role in response to other DNA-damaging agents is less well defined. We previously showed that genistein, a naturally occurring isoflavonoid, induced increased ATM protein kinase activity, ATM-dependent phosphorylation of p53 on serine 15 and activation of the DNA-binding properties of p53. Here, we show that genistein also induces phosphorylation of p53 at serines 6, 9, 20, 46, and 392, and that genistein-induced accumulation and phosphorylation of p53 is reduced in two ATM-deficient human cell lines. Also, we show that genistein induces phosphorylation of ATM on serine 1981 and phosphorylation of histone H2AX on serine 139. The related bioflavonoids, daidzein and biochanin A, did not induce either phosphorylation of p53 or ATM at these sites. Like genistein, quercetin induced phosphorylation of ATM on serine 1981, and ATM-dependent phosphorylation of histone H2AX on serine 139; however, p53 accumulation and phosphorylation on serines 6, 9, 15, 20, 46, and 392 occurred in ATM-deficient cells, indicating that ATM is not required for quercetin-induced phosphorylation of p53. Our data suggest that genistein and quercetin induce different DNA-damage induced signaling pathways that, in the case of genistein, are highly ATM-dependent but, in the case of quercetin, may be ATM-dependent only for some downstream targets.
Ye
Ruiqiong
R
Department of Biochemistry & Molecular Biology, University of Calgary, 3330 Hospital Drive, N.W., Calgary, Alta., Canada T2N 4N1.
Goodarzi
Aaron A
AA
Kurz
Ebba U
EU
Saito
Shin'ichi
S
Higashimoto
Yuichiro
Y
Lavin
Martin F
MF
Appella
Ettore
E
Anderson
Carl W
CW
Lees-Miller
Susan P
SP
D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins; D004249:DNA Damage / Q000187:drug effects*; D004268:DNA-Binding Proteins; D004789:Enzyme Activation / Q000187:drug effects; D019833:Genistein / Q000737:chemistry / Q000494:pharmacology*; D006657:Histones / Q000378:metabolism; D006801:Humans; D007529:Isoflavones / Q000737:chemistry / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011233:Precipitin Tests; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011794:Quercetin / Q000737:chemistry / Q000494:pharmacology*; D015398:Signal Transduction / Q000502:physiology*; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D006657:Histones; D007529:Isoflavones; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C004742:daidzein; D011794:Quercetin; D019833:Genistein; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; C004541:biochanin A