TY - JOUR
T1 - Protein kinase C-independent activation of c-jun and c-fos transcription by epidermal growth factor
AU - Franklin, Christopher C.
AU - Kraft, Andrew S.
N1 - Funding Information:
This work was supporte~bly National Cancer Institute grant ROI CA42533414A,m erican CanceSro ciety grant BC-33C, and Office of Naval Research grant N-00014--89-K-006C9.. CF. is supportedb y postdoe-1era[t rainingg reatC A09128f rom the NationalC ancer Institute.
PY - 1992/3/16
Y1 - 1992/3/16
N2 - Phorbol esters, epidermal growth factor (EGF) and serum induce the transient expression of the c-jun and c-fos proto-oncogenes in quiescent fibroblasts. While phorbol esters such as phorbol 12-myristate 13-acetate (PMA) are thought to induce the transcription of these genes by activating protein kinase C (PKC), the signal transduction pathway(s) mediating the effect of EGF and serum are still unclear. We have investigated whether PKC and/or calcium play a role in mediating EGF-stimulated c-jun and c-fos RNA and protein expression in quiescent NIH 3T3 fibroblasts. PMA, EGF or serum stimulated a rapid, transient increase in c-jun and c-fos expression and c-Jun protein synthesis in quiescent NIH 3T3 cells. Depletion of whole cell PKC activity by pretreatment with PMA abolished any subsequent response to PMA, but had no effect on the ability of EGF or serum to induce c-jun and c-fos RNA and c-Jun protein expression. Nuclear run-on analysis indicated that EGF-induced gene expression was due to an increase in the rate of transcription of c-jun and c-fos in both naive and PKC-depleted cells. The role of calcium in the EGF-induced expression of c-jun and c-fos was also investigated using an NIH 3T3 cell line (HER-14) overexpressing the wild type human EGF receptor. Removal of extracellular calcium by chelation with excess EGTA or use of the non-specific calcium channel blocker lanthanide, both of which abolish the EGF-induced calcium transient in HER-14 cells, had no effect on the PMA or EGF induced c-jun or c-fos response. These findings suggest that EGF induces c-jun and c-fos transcription and c-Jun protein synthesis in a manner independent of an increase in intracellular calcium or activation of PKC in quiescent NIH 3T3 cells.
AB - Phorbol esters, epidermal growth factor (EGF) and serum induce the transient expression of the c-jun and c-fos proto-oncogenes in quiescent fibroblasts. While phorbol esters such as phorbol 12-myristate 13-acetate (PMA) are thought to induce the transcription of these genes by activating protein kinase C (PKC), the signal transduction pathway(s) mediating the effect of EGF and serum are still unclear. We have investigated whether PKC and/or calcium play a role in mediating EGF-stimulated c-jun and c-fos RNA and protein expression in quiescent NIH 3T3 fibroblasts. PMA, EGF or serum stimulated a rapid, transient increase in c-jun and c-fos expression and c-Jun protein synthesis in quiescent NIH 3T3 cells. Depletion of whole cell PKC activity by pretreatment with PMA abolished any subsequent response to PMA, but had no effect on the ability of EGF or serum to induce c-jun and c-fos RNA and c-Jun protein expression. Nuclear run-on analysis indicated that EGF-induced gene expression was due to an increase in the rate of transcription of c-jun and c-fos in both naive and PKC-depleted cells. The role of calcium in the EGF-induced expression of c-jun and c-fos was also investigated using an NIH 3T3 cell line (HER-14) overexpressing the wild type human EGF receptor. Removal of extracellular calcium by chelation with excess EGTA or use of the non-specific calcium channel blocker lanthanide, both of which abolish the EGF-induced calcium transient in HER-14 cells, had no effect on the PMA or EGF induced c-jun or c-fos response. These findings suggest that EGF induces c-jun and c-fos transcription and c-Jun protein synthesis in a manner independent of an increase in intracellular calcium or activation of PKC in quiescent NIH 3T3 cells.
KW - Epidermal growth factor
KW - Protein kinase C
KW - Proto-oncogene induction
KW - Transcription
KW - fos
KW - jun
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U2 - 10.1016/0167-4889(92)90036-B
DO - 10.1016/0167-4889(92)90036-B
M3 - Article
C2 - 1554749
AN - SCOPUS:0026558295
SN - 0167-4889
VL - 1134
SP - 137
EP - 142
JO - BBA - Molecular Cell Research
JF - BBA - Molecular Cell Research
IS - 2
ER -