Rosenfeld R G, Pham H, Keller B T, Borchardt R T, Pardridge W M
Department of Pediatrics, Stanford University Medical Center, California 94305.
Biochem Biophys Res Commun. 1987 Nov 30;149(1):159-66. doi: 10.1016/0006-291x(87)91618-4.
Specific receptors for insulin-like growth factors (IGF) I and II on microvessel-free rat brain cell membranes (RBCM) and in the microvessels that constitute the blood-brain barrier (BBB) were identified and characterized by means of affinity cross-linking techniques and specific anti-receptor antibodies. Two different models of BBB were examined: isolated rat brain capillaries and cultured bovine brain microvessel endothelial cells. Cross-linking with 125-I-IGF-I, followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), revealed an alpha subunit of apparent Mr = 138,000 in both BBB preparations, compared to 120,000 in RBCM. Cross-linking was inhibited by unlabeled IGF and insulin, but not by antibody directed against the IGF-II receptor. When 125-I-IGF-II was cross-linked, followed by SDS-PAGE under reducing conditions, a major band of apparent Mr = 250,000 was identified in RBCM and both BBB preparations. This band, which migrated with an approximately equivalent Mr in both brain and BBB membranes, was inhibited by unlabeled IGF and by antibody specific for the IGF-II receptor. Thus, both rat and bovine brain microvessels possess classical Type I and II IGF receptors. While the alpha subunit of the Type I receptor of brain is smaller than that of the BBB, the Type II receptor of brain and BBB appear to be structurally and immunologically identical.
利用亲和交联技术和特异性抗受体抗体，对无微血管的大鼠脑细胞膜（RBCM）以及构成血脑屏障（BBB）的微血管中胰岛素样生长因子（IGF）Ⅰ和Ⅱ的特异性受体进行了鉴定和特性分析。研究了两种不同的血脑屏障模型：分离的大鼠脑毛细血管和培养的牛脑微血管内皮细胞。用¹²⁵I-IGF-Ⅰ进行交联，随后进行十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS-PAGE），结果显示，在两种血脑屏障制剂中均出现一条表观分子量为138,000的α亚基，而在RBCM中为120,000。未标记的IGF和胰岛素可抑制交联反应，但针对IGF-Ⅱ受体的抗体则无此作用。当用¹²⁵I-IGF-Ⅱ进行交联，随后在还原条件下进行SDS-PAGE时，在RBCM和两种血脑屏障制剂中均鉴定出一条表观分子量为250,000的主要条带。这条在脑和血脑屏障膜中迁移时具有大致相同分子量的条带，可被未标记的IGF和针对IGF-Ⅱ受体的特异性抗体所抑制。因此，大鼠和牛脑微血管均具有经典的Ⅰ型和Ⅱ型IGF受体。虽然脑Ⅰ型受体的α亚基比血脑屏障的小，但脑和血脑屏障的Ⅱ型受体在结构和免疫方面似乎是相同的。
