Beebe D C, Silver M H, Belcher K S, Van Wyk J J, Svoboda M E, Zelenka P S
Proc Natl Acad Sci U S A. 1987 Apr;84(8):2327-30. doi: 10.1073/pnas.84.8.2327.
Lentropin, a factor present in the vitreous humor of the eye, stimulates lens fiber differentiation from chicken embryo lens epithelial cells in vitro. Lentropin has been partially purified but has not been isolated in sufficient quantity or purity for direct comparison with other growth and differentiation factors. Previous studies have shown that insulin and fetal bovine serum share with lentropin the ability to stimulate lens fiber formation from cultured epithelial cells. In the present study, a number of hormones and growth factors were assayed for lentropin activity. Of those tested, the only substances that had this activity were the insulin-like growth factors (IGFs) somatomedin C (Sm-C/IGF-I) and multiplication-stimulating activity (MSA/IGF-II). Sm-C/IGF-I was approximately 30 times more potent than insulin or MSA/IGF-II in promoting fiber cell formation. A monoclonal antibody to human Sm-C/IGF-I inhibited purified Sm-C/IGF-I, fetal bovine serum, and chicken vitreous humor from stimulating fiber cell differentiation in vitro. This antibody has been shown not to crossreact with insulin and did not block insulin-stimulated lens fiber formation. These findings indicate that lentropin is related to the IGFs and that these factors may play important roles in controlling cell differentiation, in addition to their better-known ability to stimulate cell division.
促晶状体蛋白是眼玻璃体液中的一种因子，在体外可刺激鸡胚晶状体上皮细胞向晶状体纤维细胞分化。促晶状体蛋白已得到部分纯化，但尚未获得足够数量或纯度用于与其他生长和分化因子进行直接比较。以往的研究表明，胰岛素和胎牛血清与促晶状体蛋白一样，具有刺激培养的上皮细胞形成晶状体纤维的能力。在本研究中，对多种激素和生长因子进行了促晶状体蛋白活性检测。在检测的这些物质中，具有这种活性的唯一物质是胰岛素样生长因子（IGFs），即生长调节素C（Sm-C/IGF-I）和增殖刺激活性因子（MSA/IGF-II）。在促进纤维细胞形成方面，Sm-C/IGF-I的效力大约是胰岛素或MSA/IGF-II的30倍。一种针对人Sm-C/IGF-I的单克隆抗体可抑制纯化的Sm-C/IGF-I、胎牛血清和鸡玻璃体液在体外刺激纤维细胞分化。已证明该抗体与胰岛素无交叉反应，也不阻断胰岛素刺激的晶状体纤维形成。这些发现表明促晶状体蛋白与胰岛素样生长因子相关，并且这些因子除了具有众所周知的刺激细胞分裂的能力外，可能在控制细胞分化中发挥重要作用。
