TY - JOUR
T1 - Thromboxane A2 receptor-mediated epidermal growth factor receptor transactivation
T2 - Involvement of PKC-δ and PKC-ε in the shedding of epidermal growth factor receptor ligands
AU - Uchiyama, Kotomi
AU - Saito, Masaki
AU - Sasaki, Masako
AU - Obara, Yutaro
AU - Higashiyama, Shigeki
AU - Nakahata, Norimichi
N1 - Funding Information:
We greatly appreciate Dr. Thomas R. Soderling (Vollum Institute, Oregon Health and Sciences University) for providing DNA constructs of Gα q . This work was supported in part by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (No. 19659011 to N.N., No. 18790039 and No. 20790053 to Y.O. and No. 18890015 to Masaki.S.) and from the Ministry of Education, Culture, Sports, Science and Technology (Nos. 18058002 and 20054002 to N.N.).
PY - 2009/12/8
Y1 - 2009/12/8
N2 - We examined thromboxane A2 receptor (TP)-mediated transactivation of epidermal growth factor receptor (EGFR) through the shedding of EGFR ligands. A TP agonist U46619 caused the phosphorylation of EGFR in 1321N1 human astrocytoma cells, which was inhibited by an EGFR selective inhibitor AG1478 and by a disintegrin and metalloproteinase (ADAM) inhibitor TAPI-2, indicating TP stimulation caused the EGFR transactivation through the EGFR ligand shedding. Since 1321N1 cells expressed heparin-binding EGF (HB-EGF) mRNA, the mechanism of TP-mediated EGFR transactivation was examined in HEK293 cells expressing alkaline phosphatase-conjugated HB-EGF and TP. U46619 caused the shedding of HB-EGF in a time- and concentration-dependent manner. The TP-mediated shedding was inhibited by a furin inhibitor CMK, TAP-2, dominant-negative Gαq, a Gq/11 inhibitor YM254890, and also by a non-selective PKC inhibitor GF109203X and PKC down-regulation, but not by a conventional PKC inhibitor Gö6976. Furthermore, siRNAs of PKC-δ and PKC-ε inhibited U46619-induced HB-EGF shedding. Although BAPTA/AM had no effect on U46619-induced shedding of HB-EGF, EGTA inhibited it. These results suggest that TP-mediated EGFR transactivation is partially caused by shedding of HB-EGF, which involves furin and ADAM via novel types of PKCs (PKC-δ and PKC-ε) through Gαq/11 proteins in an extracellular Ca2+-dependent manner.
AB - We examined thromboxane A2 receptor (TP)-mediated transactivation of epidermal growth factor receptor (EGFR) through the shedding of EGFR ligands. A TP agonist U46619 caused the phosphorylation of EGFR in 1321N1 human astrocytoma cells, which was inhibited by an EGFR selective inhibitor AG1478 and by a disintegrin and metalloproteinase (ADAM) inhibitor TAPI-2, indicating TP stimulation caused the EGFR transactivation through the EGFR ligand shedding. Since 1321N1 cells expressed heparin-binding EGF (HB-EGF) mRNA, the mechanism of TP-mediated EGFR transactivation was examined in HEK293 cells expressing alkaline phosphatase-conjugated HB-EGF and TP. U46619 caused the shedding of HB-EGF in a time- and concentration-dependent manner. The TP-mediated shedding was inhibited by a furin inhibitor CMK, TAP-2, dominant-negative Gαq, a Gq/11 inhibitor YM254890, and also by a non-selective PKC inhibitor GF109203X and PKC down-regulation, but not by a conventional PKC inhibitor Gö6976. Furthermore, siRNAs of PKC-δ and PKC-ε inhibited U46619-induced HB-EGF shedding. Although BAPTA/AM had no effect on U46619-induced shedding of HB-EGF, EGTA inhibited it. These results suggest that TP-mediated EGFR transactivation is partially caused by shedding of HB-EGF, which involves furin and ADAM via novel types of PKCs (PKC-δ and PKC-ε) through Gαq/11 proteins in an extracellular Ca2+-dependent manner.
KW - Epidermal growth factor receptor
KW - G protein
KW - Heparin-binding epidermal growth factor
KW - Protein kinase C
KW - Thromboxane A receptor
KW - Transactivation
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U2 - 10.1016/j.ejps.2009.09.016
DO - 10.1016/j.ejps.2009.09.016
M3 - Article
C2 - 19804825
AN - SCOPUS:70449522901
VL - 38
SP - 504
EP - 511
JO - European Journal of Pharmaceutical Sciences
JF - European Journal of Pharmaceutical Sciences
SN - 0928-0987
IS - 5
ER -