TY - JOUR
T1 - Caspase-mediated cleavage of ATM during cisplatin-induced tubular cell apoptosis
T2 - Inactivation of its kinase activity toward p53
AU - Wang, Jinzhao
AU - Pabla, Navjotsingh
AU - Wang, Cong Yi
AU - Wang, Weixin
AU - Schoenlein, Patricia V.
AU - Dong, Zheng
PY - 2006
Y1 - 2006
N2 - Cisplatin induces renal cell injury and death, resulting in nephrotoxicity that limits its use in cancer therapy. Using cell culture models, recent work has suggested the involvement of p53 in renal cell apoptosis during cisplatin treatment. However, the signals upstream of p53 remain elusive. ATM and ATR are critical regulators of p53 under various conditions of DNA damage. Here, we show that ATM, and not ATR, was proteolytically cleaved into specific fragments of ∼210 and 150 kDa during cisplatin-induced tubular cell apoptosis. ATM cleavage was paralleled by the development of apoptosis. VAD, a broad-spectrum inhibitor of caspases, attenuated the cleavage of ATM, whereas the inhibitors of specific caspases were less effective. In caspase-3-deficient MCF-7 cells, ATM was cleaved, releasing the 210- but not the 150-kDa fragment. Recombinant caspase-3 was much more effective than caspase-7 in cleaving ATM that was immunoprecipitated from cell lysates. During cisplatin incubation, VAD protected ATM and enhanced p53 phosphorylation. In vitro assay of protein kinase activity further showed that ATM immunoprecipitated from cisplatin-treated cells had significantly lower kinase activity toward p53 than that from control cells. Importantly, the protein kinase activity was restored in ATM that was protected by VAD during cisplatin incubation. ATM deficiency sensitized the cells to cisplatin-induced apoptosis, suggesting a cytoprotective role of ATM in this experimental model. Thus proteolysis of ATM by caspases may inactivate this regulatory molecule to facilitate the progression of apoptosis.
AB - Cisplatin induces renal cell injury and death, resulting in nephrotoxicity that limits its use in cancer therapy. Using cell culture models, recent work has suggested the involvement of p53 in renal cell apoptosis during cisplatin treatment. However, the signals upstream of p53 remain elusive. ATM and ATR are critical regulators of p53 under various conditions of DNA damage. Here, we show that ATM, and not ATR, was proteolytically cleaved into specific fragments of ∼210 and 150 kDa during cisplatin-induced tubular cell apoptosis. ATM cleavage was paralleled by the development of apoptosis. VAD, a broad-spectrum inhibitor of caspases, attenuated the cleavage of ATM, whereas the inhibitors of specific caspases were less effective. In caspase-3-deficient MCF-7 cells, ATM was cleaved, releasing the 210- but not the 150-kDa fragment. Recombinant caspase-3 was much more effective than caspase-7 in cleaving ATM that was immunoprecipitated from cell lysates. During cisplatin incubation, VAD protected ATM and enhanced p53 phosphorylation. In vitro assay of protein kinase activity further showed that ATM immunoprecipitated from cisplatin-treated cells had significantly lower kinase activity toward p53 than that from control cells. Importantly, the protein kinase activity was restored in ATM that was protected by VAD during cisplatin incubation. ATM deficiency sensitized the cells to cisplatin-induced apoptosis, suggesting a cytoprotective role of ATM in this experimental model. Thus proteolysis of ATM by caspases may inactivate this regulatory molecule to facilitate the progression of apoptosis.
KW - ATR
KW - DNA damage
KW - Kidney
KW - Nephrotoxicity
KW - Proteolysis
UR - http://www.scopus.com/inward/record.url?scp=33845359674&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33845359674&partnerID=8YFLogxK
U2 - 10.1152/ajprenal.00509.2005
DO - 10.1152/ajprenal.00509.2005
M3 - Article
C2 - 16849690
AN - SCOPUS:33845359674
SN - 0363-6127
VL - 291
SP - F1300-F1307
JO - American Journal of Physiology - Renal Physiology
JF - American Journal of Physiology - Renal Physiology
IS - 6
ER -