TY - JOUR
T1 - MAPK regulate p53-dependent cell death induced by benzo[a]pyrene
T2 - Involvement of p53 phosphorylation and acetylation
AU - Lin, T.
AU - MAK, Nai Ki
AU - Yang, M. S.
N1 - Funding Information:
The study was supported by the Hong Kong Baptist University Faculty Research Grant. Lin was supported by the special RPg quota from the Research Grant Council, Hong Kong.
PY - 2008/5/21
Y1 - 2008/5/21
N2 - Benzo[a]pyrene (BaP) is a potentially genotoxic and cytotoxic environmental pollutant. Previous studies showed that exposure of HepG2 cells to BaP causes necrotic cell death [Lin, T., Yang, M.S., 2007b. Cell death induced by benzo[a]pyrene in the HepG2 cells is dependent on PARP-1 activation and NAD depletion. Toxicology 245, 147-153]. In the present study, the signaling pathways associated with this response was studied. BaP induced accumulation and activation of p53 in HepG2 cells, which occurred as early as 12 h after exposure. Activation of p53 was evidenced by its phosphorylation at serine 15 (Ser15) and acetylation at lysine 382 (Lys382). Chemical inhibition and siRNA-mediated knockdown of p53 expression suppressed its phosphorylation as well as cell death. BaP also activated p38 MAPK and ERK, but not JNK, at 6 h after exposure. SB203580 and PD98059, specific inhibitors of p38 MAPK and ERK, respectively, suppressed phosphorylation of p53 at Ser15, but the accumulation of p53 was only moderately reduced. Acetylation of p53 at Lys 382 was not affected by these inhibitors, suggesting that acetylation stabilizes p53 in response to DNA damage. SB203580 and PD98059 prevented downstream energy failure and BaP-induced cell death. Similar results were obtained with siRNA against two isoforms of p38 MAPK, p38α and p38β. Wortmannin, selective inhibitor of DNA-PK and ATM/ATR, abolished p53 phosphorylation, indicating an involvement of multiple pathways of p53 phosphorylation upon exposure to BaP. In summary, the current study demonstrated that both MAPK and p53 activation are required for BaP-induced necrotic cell death. The results also provide a novel model for studying the regulation between p53 and p38 MAPK in the progression of cellular necrosis.
AB - Benzo[a]pyrene (BaP) is a potentially genotoxic and cytotoxic environmental pollutant. Previous studies showed that exposure of HepG2 cells to BaP causes necrotic cell death [Lin, T., Yang, M.S., 2007b. Cell death induced by benzo[a]pyrene in the HepG2 cells is dependent on PARP-1 activation and NAD depletion. Toxicology 245, 147-153]. In the present study, the signaling pathways associated with this response was studied. BaP induced accumulation and activation of p53 in HepG2 cells, which occurred as early as 12 h after exposure. Activation of p53 was evidenced by its phosphorylation at serine 15 (Ser15) and acetylation at lysine 382 (Lys382). Chemical inhibition and siRNA-mediated knockdown of p53 expression suppressed its phosphorylation as well as cell death. BaP also activated p38 MAPK and ERK, but not JNK, at 6 h after exposure. SB203580 and PD98059, specific inhibitors of p38 MAPK and ERK, respectively, suppressed phosphorylation of p53 at Ser15, but the accumulation of p53 was only moderately reduced. Acetylation of p53 at Lys 382 was not affected by these inhibitors, suggesting that acetylation stabilizes p53 in response to DNA damage. SB203580 and PD98059 prevented downstream energy failure and BaP-induced cell death. Similar results were obtained with siRNA against two isoforms of p38 MAPK, p38α and p38β. Wortmannin, selective inhibitor of DNA-PK and ATM/ATR, abolished p53 phosphorylation, indicating an involvement of multiple pathways of p53 phosphorylation upon exposure to BaP. In summary, the current study demonstrated that both MAPK and p53 activation are required for BaP-induced necrotic cell death. The results also provide a novel model for studying the regulation between p53 and p38 MAPK in the progression of cellular necrosis.
KW - Benzo[a]pyrene
KW - Cell death
KW - ERK
KW - HepG
KW - p38 MAPK
KW - p53
UR - http://www.scopus.com/inward/record.url?scp=42749090537&partnerID=8YFLogxK
U2 - 10.1016/j.tox.2008.02.017
DO - 10.1016/j.tox.2008.02.017
M3 - Journal article
C2 - 18406507
AN - SCOPUS:42749090537
SN - 0300-483X
VL - 247
SP - 145
EP - 153
JO - Toxicology
JF - Toxicology
IS - 2-3
ER -