DNA Damage Regulates Chk2 Association with Chromatin

@article{citeulike:845910, abstract = {DNA damage triggers cellular signaling pathways that control the cell cycle and DNA repair. Chk2 is a critical mediator of diverse responses to DNA damage. Chk2 transmits signals from upstream phosphatidylinositol 3'-kinase-like kinases to effector substrates including p53, Brca1, Cdc25A, and Cdc25C. Using chromatin fractionation as well as immunostaining combined with detergent pre-extraction, we have found that a small pool of Chk2 is associated with chromatin prior to DNA damage. Recovery of chromatin-bound Chk2 is reduced in an ATM-dependent manner by exposure to ionizing radiation. Camptothecin and adriamycin also reduce the amount of chromatin-associated Chk2. The Thr68-phosphorylated forms of Chk2 induced by DNA damage are found in soluble fractions, but not in the chromatin-enriched fraction. Functional serine/threonine glutamine cluster domain, forkhead-associated domain, and kinase activity are all required for efficient reduction of chromatin-bound Chk2 in response to DNA damage. Artificial induction of Chk2 oligomerization concomitant with exposure to low dose ionizing radiation reduces chromatin-bound Chk2. When Chk2 is incubated with chromatin-enriched fractions in vitro in the presence of ATP, hyperphosphorylated forms of Chk2 bind more weakly to chromatin than hypophosphorylated forms. Taken together, our data suggest that DNA damage induces activation of chromatin-bound Chk2 by a chromatin-derived signal, and that this results in dissociation of activated Chk2 from chromatin, facilitating further signal amplification and transmission to soluble substrates. 10.1074/jbc.M509299200}, author = {Li, Jia and Stern, David F. }, citeulike-article-id = {845910}, doi = {http://dx.doi.org/10.1074/jbc.M509299200}, journal = {J. Biol. Chem.}, keywords = {checkpoint, dna\_damage, rad53}, month = {November}, number = {45}, pages = {37948--37956}, posted-at = {2006-09-15 21:36:48}, priority = {2}, title = {DNA Damage Regulates Chk2 Association with Chromatin}, url = {http://dx.doi.org/10.1074/jbc.M509299200}, volume = {280}, year = {2005} }

TY - JOUR ID - citeulike:845910 L3 - citeulike-article-id:845910 TI - DNA Damage Regulates Chk2 Association with Chromatin JF - J. Biol. Chem. VL - 280 IS - 45 SP - 37948 EP - 37956 N2 - DNA damage triggers cellular signaling pathways that control the cell cycle and DNA repair. Chk2 is a critical mediator of diverse responses to DNA damage. Chk2 transmits signals from upstream phosphatidylinositol 3'-kinase-like kinases to effector substrates including p53, Brca1, Cdc25A, and Cdc25C. Using chromatin fractionation as well as immunostaining combined with detergent pre-extraction, we have found that a small pool of Chk2 is associated with chromatin prior to DNA damage. Recovery of chromatin-bound Chk2 is reduced in an ATM-dependent manner by exposure to ionizing radiation. Camptothecin and adriamycin also reduce the amount of chromatin-associated Chk2. The Thr68-phosphorylated forms of Chk2 induced by DNA damage are found in soluble fractions, but not in the chromatin-enriched fraction. Functional serine/threonine glutamine cluster domain, forkhead-associated domain, and kinase activity are all required for efficient reduction of chromatin-bound Chk2 in response to DNA damage. Artificial induction of Chk2 oligomerization concomitant with exposure to low dose ionizing radiation reduces chromatin-bound Chk2. When Chk2 is incubated with chromatin-enriched fractions in vitro in the presence of ATP, hyperphosphorylated forms of Chk2 bind more weakly to chromatin than hypophosphorylated forms. Taken together, our data suggest that DNA damage induces activation of chromatin-bound Chk2 by a chromatin-derived signal, and that this results in dissociation of activated Chk2 from chromatin, facilitating further signal amplification and transmission to soluble substrates. 10.1074/jbc.M509299200 KW - checkpoint KW - dna_damage KW - rad53 AU - Li, Jia AU - Stern, David PY - 2005/11/11/ UR - http://dx.doi.org/10.1074/jbc.M509299200 ER -