Matsui Junji, Wakabayashi Toshiaki, Asada Makoto, Yoshimatsu Kentaro, Okada Masayuki
Tsukuba Research Laboratories, Eisai Co., Ltd., 5-1-3, Tokodai, Tsukuba, Ibaraki 300-2635, Japan.
J Biol Chem. 2004 Apr 30;279(18):18600-7. doi: 10.1074/jbc.M311643200. Epub 2004 Feb 24.
c-kit receptor tyrosine kinase is a marker of progenitor cells, which differentiate into blood and/or vascular endothelial cells, and has an important role in the amplification/mobilization of progenitor cells. c-kit is expressed in mature endothelial cells, but its role there is unclear. Stem cell factor, a c-kit ligand, dose-dependently promoted survival, migration, and capillary tube formation of human umbilical vein endothelial cells. These effects mimicked those of vascular endothelial growth factor, except that stem cell factor did not sufficiently support proliferation of these cells. After exposing cells to this factor, Akt, Erk1/2, and c-kit were immediately (</=5 min) and dose-dependently tyrosinephosphorylated. STI-571, a c-kit inhibitor, dose-dependently attenuated these phosphorylations and inhibited stem cell factor-promoted survival and capillary tube formation over the same dose range. Wortmannin and LY294002, inhibitors of phosphoinositide 3-kinase, and PD98059, an inhibitor of MEK, abrogated survival and capillary tube formation, indicating that Akt and Erk1/2 should promote survival and capillary tube formation of these endothelial cells at a locus downstream to stem cell factor/c-kit signaling. Akt was more strongly phosphorylated, whereas Erk1/2 and p38 were more weakly phosphorylated with stem cell factor than with vascular endothelial growth factor. Phospholipase Cgamma was phosphorylated only with the latter, indicating that stem cell factor/c-kit signaling is somewhat different.
c-kit受体酪氨酸激酶是祖细胞的标志物，祖细胞可分化为血液和/或血管内皮细胞，并且在祖细胞的扩增/动员中起重要作用。c-kit在成熟内皮细胞中表达，但其在其中的作用尚不清楚。干细胞因子是一种c-kit配体，可剂量依赖性地促进人脐静脉内皮细胞的存活、迁移和毛细血管管腔形成。这些作用类似于血管内皮生长因子的作用，只是干细胞因子不能充分支持这些细胞的增殖。将细胞暴露于该因子后，Akt、Erk1/2和c-kit立即（≤5分钟）且呈剂量依赖性地酪氨酸磷酸化。c-kit抑制剂STI-571在相同剂量范围内呈剂量依赖性地减弱这些磷酸化，并抑制干细胞因子促进的存活和毛细血管管腔形成。磷酸肌醇3-激酶抑制剂渥曼青霉素和LY294002以及MEK抑制剂PD98059消除了细胞存活和毛细血管管腔形成，表明Akt和Erk1/2应该在干细胞因子/c-kit信号传导下游的位点促进这些内皮细胞的存活和毛细血管管腔形成。与血管内皮生长因子相比，干细胞因子使Akt磷酸化更强，而使Erk1/2和p38磷酸化更弱。磷脂酶Cγ仅被后者磷酸化，表明干细胞因子/c-kit信号传导有所不同。
