Sankar S, Mahooti-Brooks N, Centrella M, McCarthy T L, Madri J A
Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
J Biol Chem. 1995 Jun 2;270(22):13567-72. doi: 10.1074/jbc.270.22.13567.
Bovine aortic endothelial cells (BAECs) express both type I and type II receptors for transforming growth factor beta (TGF beta). These cells respond to TGF beta 1 but are relatively refractory to another isoform of TGF beta, termed TGF beta 2. TGF beta s are thought to signal through receptor complexes composed of type I and/or type II receptors, both of which appear to be functional serine-threonine kinases. The TGF beta type III receptor, on the other hand, does not seem to have any direct signaling capacity. We have now stably transfected BAECs with the type III receptor cDNA. These cells displayed surface expression of the type III receptor protein, as determined by cross-linking with iodinated TGF beta 1 and immunoprecipitation with antibodies to the type III receptor protein. Transfected BAECs exhibit increased responsiveness to TGF beta 2 by several different criteria including an increase in plasminogen activator inhibitor-1 protein and inhibition of migration and proliferation. Thus, the type III receptor protein may play a role in presenting TGF beta 2 to the type II receptor and increase responsiveness to TGF beta 2 to a level comparable to that of TGF beta 1.
牛主动脉内皮细胞（BAECs）表达转化生长因子β（TGFβ）的I型和II型受体。这些细胞对TGFβ1有反应，但对另一种TGFβ同工型，即TGFβ2相对不敏感。TGFβs被认为通过由I型和/或II型受体组成的受体复合物进行信号传导，这两种受体似乎都是功能性丝氨酸 - 苏氨酸激酶。另一方面，TGFβIII型受体似乎没有任何直接的信号传导能力。我们现在已经用III型受体cDNA稳定转染了BAECs。通过与碘化TGFβ1交联并用针对III型受体蛋白的抗体进行免疫沉淀测定，这些细胞显示出III型受体蛋白的表面表达。通过几种不同的标准，包括纤溶酶原激活物抑制剂 - 1蛋白的增加以及迁移和增殖的抑制，转染的BAECs对TGFβ2的反应性增加。因此，III型受体蛋白可能在将TGFβ2呈递给II型受体并将对TGFβ2的反应性提高到与TGFβ1相当的水平方面发挥作用。
