Moriarty P, Boulton M, Dickson A, McLeod D
Department of Ophthalmology, University of Manchester.
Br J Ophthalmol. 1994 Aug;78(8):638-42. doi: 10.1136/bjo.78.8.638.
Insulin-like growth factor I (IGF-I) and its associated binding proteins (IGFBPs) have been identified in retinal tissues but their precise cellular origin remains unclear. The aim of this study was to examine the ability of three retinal cell types (microvascular endothelial cells, pericytes, and pigment epithelial cells) and a non-retinal cell type (Tenon's fibroblasts) to produce IGF-I and cell specific IGFBPs in vitro. Using a radioimmunoassay we demonstrated that all four cell types produce IGF-I and that this production continued over a 72 hour period. In addition, western ligand blotting revealed that each cell type produced at least one IGFBP and that each cell type produced a different IGFBP profile. Endothelial cells produced a 24 kDa band only, pericytes produced both a 24 kDa and a 34 kDa band, retinal pigment epithelial cells produced a 38-41 kDa band, while fibroblasts produced both a 24 kDa and a 30 kDa band. Laser scanning densitometry demonstrated that in the majority of experiments the IGFBPs accumulated in the culture medium over a 72 hour period. Neither IGF-I nor IGFBPs were observed in cell lysates indicating de novo synthesis and secretion in vitro. These results suggest an autocrine/paracrine function for IGF-I and its associated binding proteins which may play a significant role in both retinal physiology and disease.
胰岛素样生长因子I（IGF-I）及其相关结合蛋白（IGFBPs）已在视网膜组织中被鉴定出来，但其确切的细胞来源仍不清楚。本研究的目的是检测三种视网膜细胞类型（微血管内皮细胞、周细胞和色素上皮细胞）以及一种非视网膜细胞类型（提上睑肌成纤维细胞）在体外产生IGF-I和细胞特异性IGFBPs的能力。使用放射免疫测定法，我们证明所有四种细胞类型均产生IGF-I，且这种产生在72小时内持续存在。此外，Western配体印迹显示每种细胞类型至少产生一种IGFBP，且每种细胞类型产生不同的IGFBP谱。内皮细胞仅产生一条24 kDa的条带，周细胞产生一条24 kDa和一条34 kDa的条带，视网膜色素上皮细胞产生一条38 - 41 kDa的条带，而成纤维细胞产生一条24 kDa和一条30 kDa的条带。激光扫描密度测定法表明，在大多数实验中，IGFBPs在培养基中72小时内积累。在细胞裂解物中未观察到IGF-I和IGFBPs，表明在体外是从头合成和分泌。这些结果提示IGF-I及其相关结合蛋白具有自分泌/旁分泌功能，这可能在视网膜生理和疾病中都发挥重要作用。
