Bachrach L K, Eggo M C, Hintz R L, Burrow G N
Department of Pediatrics, Stanford University Medical Center, CA 94305.
Biochem Biophys Res Commun. 1988 Aug 15;154(3):861-7. doi: 10.1016/0006-291x(88)90219-7.
Sheep thyroid cells cultured in serum-free medium were used to study the biologic activity, binding, and production of the insulin-like growth factors (IGFs). IGF-I, IGF-II, and insulin stimulated thyroid cell division. Abundant, specific IGF receptors on sheep thyroid cell membranes were identified by binding displacement studies. Maximal specific binding of [125I]-labeled IGF-I and IGF-II to 25 micrograms of membrane protein averaged 21% and 27% respectively. The presence of type I and type II IGF receptors was confirmed by polyacrylamide gel electrophoresis of [125I]IGFs covalently cross-linked to cell membranes. Under reducing conditions, [125I]IGF-I bound to a moiety of approximate Mr = 135,000 and [125I]IGF-II to a moiety of approximate Mr = 260,000. Cross-linking of [125I]IGF-I to medium conditioned by thyroid cells indicated the presence of four IGF binding proteins with apparent Mr = 34,000, 26,000, 19,000 and 14,000. Thyroid cells also secreted IGF-I and II into the medium. IGF synthesis was enhanced consistently by recombinant growth hormone. These data indicate that sheep thyroid cells are a site for IGF action, binding, and production and provide further evidence that IGFs may modulate thyroid gland growth in an autocrine or paracrine manner.
在无血清培养基中培养的绵羊甲状腺细胞被用于研究胰岛素样生长因子（IGF）的生物活性、结合及产生情况。IGF-I、IGF-II和胰岛素可刺激甲状腺细胞分裂。通过结合置换研究鉴定出绵羊甲状腺细胞膜上存在丰富的特异性IGF受体。[125I]标记的IGF-I和IGF-II与25微克膜蛋白的最大特异性结合平均分别为21%和27%。通过对与细胞膜共价交联的[125I]IGF进行聚丙烯酰胺凝胶电泳，证实了I型和II型IGF受体的存在。在还原条件下，[125I]IGF-I与一个相对分子质量约为135,000的部分结合，[125I]IGF-II与一个相对分子质量约为260,000的部分结合。[125I]IGF-I与甲状腺细胞条件培养基的交联表明存在四种表观相对分子质量分别为34,000、26,000、19,000和14,000的IGF结合蛋白。甲状腺细胞也将IGF-I和II分泌到培养基中。重组生长激素可持续增强IGF的合成。这些数据表明绵羊甲状腺细胞是IGF作用、结合及产生的场所，并进一步证明IGF可能以自分泌或旁分泌方式调节甲状腺生长。
