TY - JOUR
T1 - Ah receptor-mediated suppression of liver regeneration through NC-XRE-driven p21Cip1 expression
AU - Jackson, Daniel P.
AU - Li, Hui
AU - Mitchell, Kristen A.
AU - Joshi, Aditya D.
AU - Elferink, Cornelis J.
PY - 2014/4
Y1 - 2014/4
N2 - Previous studies in hepatocyte-derived cell lines and the whole liver established that the aryl hydrocarbon receptor (AhR) can disrupt G 1-phase cell cycle progression following exposure to persistent AhR agonists, such as TCDD (dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin). Growth arrest was attributed to inhibition of G1-phase cyclin-dependent kinase 2 (CDK2) activity. The present study examined the effect of TCDD exposure on liver regeneration following 70% partial hepatectomy in mice lacking the Cip/Kip inhibitors p21Cip1 or p27Kip1 responsible for regulating CDK2 activity. Assessment of the regenerative process in wild-type, p21Cip1 knockout, and p27Kip1 knockout mice confirmed that TCDD-induced inhibition of liver regeneration is entirely dependent on p21 Cip1 expression. Compared with wild-type mice, the absence of p21Cip1 expression completely abrogated the TCDD inhibition, and accelerated hepatocyte progression through G1 phase during the regenerative process. Analysis of the transcriptional response determined that increased p21Cip1 expression during liver regeneration involved an AhR-dependent mechanism. Chromatin immunoprecipitation studies revealed that p21Cip1 induction required AhR binding to the newly characterized nonconsensus xenobiotic response element, in conjunction with the tumor suppressor protein Kruppel-like factor 6 functioning as an AhR binding partner. The evidence also suggests that AhR functionality following partial hepatectomy is dependent on a p21Cip1-regulated signaling process, intimately linking AhR biology to the G1-phase cell cycle program.
AB - Previous studies in hepatocyte-derived cell lines and the whole liver established that the aryl hydrocarbon receptor (AhR) can disrupt G 1-phase cell cycle progression following exposure to persistent AhR agonists, such as TCDD (dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin). Growth arrest was attributed to inhibition of G1-phase cyclin-dependent kinase 2 (CDK2) activity. The present study examined the effect of TCDD exposure on liver regeneration following 70% partial hepatectomy in mice lacking the Cip/Kip inhibitors p21Cip1 or p27Kip1 responsible for regulating CDK2 activity. Assessment of the regenerative process in wild-type, p21Cip1 knockout, and p27Kip1 knockout mice confirmed that TCDD-induced inhibition of liver regeneration is entirely dependent on p21 Cip1 expression. Compared with wild-type mice, the absence of p21Cip1 expression completely abrogated the TCDD inhibition, and accelerated hepatocyte progression through G1 phase during the regenerative process. Analysis of the transcriptional response determined that increased p21Cip1 expression during liver regeneration involved an AhR-dependent mechanism. Chromatin immunoprecipitation studies revealed that p21Cip1 induction required AhR binding to the newly characterized nonconsensus xenobiotic response element, in conjunction with the tumor suppressor protein Kruppel-like factor 6 functioning as an AhR binding partner. The evidence also suggests that AhR functionality following partial hepatectomy is dependent on a p21Cip1-regulated signaling process, intimately linking AhR biology to the G1-phase cell cycle program.
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U2 - 10.1124/mol.113.089730
DO - 10.1124/mol.113.089730
M3 - Article
C2 - 24431146
AN - SCOPUS:84896889925
SN - 0026-895X
VL - 85
SP - 533
EP - 541
JO - Molecular pharmacology
JF - Molecular pharmacology
IS - 4
ER -