TY - JOUR
T1 - Gene Expression Changes Associated with the Endoplasmic Reticulum Stress Response Induced by Microsomal Cytochrome P450 Overproduction
AU - Szczesna-Skorupa, Elzbieta
AU - Chen, Ci Di
AU - Liu, Hong
AU - Kemper, Byron
N1 - Funding Information:
I wish to thank my colleagues Miss P. N. Crisp and Mr. J. G. Buwalda, and Professor T. W. Walker for stimulating my interest in pasture plant relations. I am also indebted to the University Grants Committee and the Public Trust for financial assistance.
PY - 2004/4/2
Y1 - 2004/4/2
N2 - Induction of drug-metabolizing microsomal cytochromes P450 (P450s) results in a striking proliferation of the smooth endoplasmic reticulum (ER). Overexpression of P450s in yeast and cultured cells produces a similar response. The signals mediating this process are not known but probably involve signal transduction pathways involved in the unfolded protein response (UPR) or the ER overload response (EOR). We have examined the temporal response of specific genes in these pathways and genes globally to overexpression of P450 in cultured cells. Activity of NFκB, an EOR component, was substantially increased by overexpression of full-length P450 2C2 or a chimera with the 28-amino acid signal anchor sequence of P450 2C2 in HepG2 cells, and the activation correlated temporally with the accumulation of P450 in the cells. In the UPR pathway, activation of the transcription factor XBP1 by IRE1 also correlated with the accumulation of P450 in the cells, and in contrast, maximum activation of the BiP/grp78 promoter preceded the accumulation. Differential effects of expression of P450 on apoptosis were observed in non-hepatic COS1 and hepatic HepG2 cells. In COS1 cells, apoptosis was induced, and this correlated with sustained activation of the pro-apoptotic JNK pathway, induction of CHOP, and an absence of the increased NFκB activity. In HepG2 cells, JNK was only transiently activated, and CHOP expression was not induced. As assessed by DNA microarray analysis, up-regulation of signaling genes was predominant including those involved in anti-apoptosis and ER stress. These results suggest that both the EOR and UPR pathways are involved in the cellular response to induction of P450 expression and that in hepatic cells genes are also induced to block apoptosis, which may be a physiologically relevant response to prevent cell death during xenobiotic induced expression of P450 in the liver.
AB - Induction of drug-metabolizing microsomal cytochromes P450 (P450s) results in a striking proliferation of the smooth endoplasmic reticulum (ER). Overexpression of P450s in yeast and cultured cells produces a similar response. The signals mediating this process are not known but probably involve signal transduction pathways involved in the unfolded protein response (UPR) or the ER overload response (EOR). We have examined the temporal response of specific genes in these pathways and genes globally to overexpression of P450 in cultured cells. Activity of NFκB, an EOR component, was substantially increased by overexpression of full-length P450 2C2 or a chimera with the 28-amino acid signal anchor sequence of P450 2C2 in HepG2 cells, and the activation correlated temporally with the accumulation of P450 in the cells. In the UPR pathway, activation of the transcription factor XBP1 by IRE1 also correlated with the accumulation of P450 in the cells, and in contrast, maximum activation of the BiP/grp78 promoter preceded the accumulation. Differential effects of expression of P450 on apoptosis were observed in non-hepatic COS1 and hepatic HepG2 cells. In COS1 cells, apoptosis was induced, and this correlated with sustained activation of the pro-apoptotic JNK pathway, induction of CHOP, and an absence of the increased NFκB activity. In HepG2 cells, JNK was only transiently activated, and CHOP expression was not induced. As assessed by DNA microarray analysis, up-regulation of signaling genes was predominant including those involved in anti-apoptosis and ER stress. These results suggest that both the EOR and UPR pathways are involved in the cellular response to induction of P450 expression and that in hepatic cells genes are also induced to block apoptosis, which may be a physiologically relevant response to prevent cell death during xenobiotic induced expression of P450 in the liver.
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U2 - 10.1074/jbc.M312170200
DO - 10.1074/jbc.M312170200
M3 - Article
C2 - 14718536
AN - SCOPUS:1842740450
SN - 0021-9258
VL - 279
SP - 13953
EP - 13961
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 14
ER -