Thromboxane A2 receptor-mediated epidermal growth factor receptor transactivation: involvement of PKC-delta and PKC-epsilon in the shedding of epidermal growth factor receptor ligands.
Thromboxane A2 receptor-mediated epidermal growth factor receptor transactivation: involvement of PKC-delta and PKC-epsilon in the shedding of epidermal growth factor receptor ligands.
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DOI：
10.1016/j.ejps.2009.09.016
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发表时间：
2009-12
期刊：
影响因子：
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通讯作者：
Kotomi Uchiyama;Masaki Saito;Masako Sasaki;Y. Obara;S. Higashiyama;N. Nakahata
中科院分区：
文献类型：
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作者：
Kotomi Uchiyama;Masaki Saito;Masako Sasaki;Y. Obara;S. Higashiyama;N. Nakahata
我们研究了血栓素A2受体（TP）介导的表皮生长因子受体（EGFR）的反式激活，通过脱落的EGFR配体。TP激动剂U46619引起1321 N1人星形细胞瘤细胞中EGFR的磷酸化，其被EGFR选择性抑制剂AG 1478和去整合素和金属蛋白酶（ADAM）抑制剂TAPI-2抑制，表明TP刺激通过EGFR配体脱落引起EGFR反式激活。由于1321 N1细胞表达肝素结合EGF（HB-EGF）mRNA，因此在表达碱性磷酸酶结合HB-EGF和TP的HEK 293细胞中检查TP介导的EGFR反式激活机制。U46619以时间和浓度依赖性方式引起HB-EGF的脱落。弗林蛋白酶抑制剂CMK、TAP-2、显性阴性Gαq、Gq/11抑制剂YM 254890以及非选择性PKC抑制剂GF 109203 X和PKC下调均可抑制TP介导的脱落，但常规PKC抑制剂Gö 6976不抑制TP介导的脱落。此外，PKC-δ和PKC-β的siRNA抑制U46619诱导的HB-EGF脱落。提示TP介导的EGFR反式激活部分是由HB-EGF的脱落引起的，其中furin和ADAM通过新型PKC（PKC-δ和PKC-β）以细胞外Ca ~（2+）依赖的方式通过Gαq/11蛋白参与。
We examined thromboxane A2receptor (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/11inhibitor 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-ɛ 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-ɛ) through Gαq/11proteins in an extracellular Ca2+-dependent manner.