The
CCAAT/enhancer binding protein delta (C/EBPdelta, CRP3, CELF, NF-IL6beta) regulates gene expression and plays functional roles in many tissues, such as in
acute phase response to inflammatory stimuli, adipocyte differentiation, and mammary epithelial cell growth control. In this study, we examined the expression of human C/EBPdelta (NF-IL6beta) gene by
epidermal growth factor (
EGF) stimulation in human
epidermoid carcinoma A431 cells. NF-IL6beta was an immediate-early gene activated by the
EGF-induced signaling pathways in cells. By using 5'-serial deletion reporter analysis, we showed that the region comprising the -347 to +9 base pairs was required for
EGF response of the NF-IL6beta promoter. This region contains putative consensus binding sequences of Sp1 and
cAMP response element-binding protein (CREB). The NF-IL6beta promoter activity induced by
EGF was abolished by mutating the sequence of cAMP response element or Sp1 sites in the -347/+9 base pairs region. Both in vitro and in vivo
DNA binding assay revealed that the CREB binding activity was low in
EGF-starved cells, whereas it was induced within 30 min after
EGF treatment of A431 cells. However, no change in Sp1 binding activity was found by
EGF treatment. Moreover, the
phosphatidylinositol 3 (PI3)-kinase inhibitor (
wortmannin) and
p38(MAPK) inhibitor (
SB203580) inhibited the
EGF-induced CREB phosphorylation and the expression of NF-IL6beta gene in cells. We also demonstrated that CREB was involved in regulating the NF-IL6beta gene transcriptional activity mediated by
p38(MAPK). Our results suggested that
PI3-kinase/
p38(MAPK)/CREB pathway contributed to the
EGF activation of NF-IL6beta gene expression.