Connelly T G, Green M S
Department of Anatomy and Cell Biology, University of Michigan, Ann Arbor 48109-0010.
J Exp Zool. 1987 Aug;243(2):233-43. doi: 10.1002/jez.1402430209.
Removal of the ocular lens in adult newts (Notophthalmus viridescens) is followed by a series of cellular events leading to regeneration of a new lens by cell type conversion of pigmented iris epithelial cells at the dorsal pupillary margin (Yamada, Curr. Top. Dev. Biol. 2:247-283, 1967). Following depigmentation and five to seven cell divisions, iris epithelial cells redifferentiate into lens fiber cells and synthesize crystallin proteins (Yamada, Curr. Top. Dev. Biol. 2:247-283, 1967). This process is dependent upon neural retina in vivo (Stone, Anat. Rec. 131:151-172, 1958; Reyer, Dev. Biol. 14:214-225, 1966) and in vitro (Yamada et al., Differentiation 1:65-82, 1973). Acting on the hypothesis that the role of the neural retina is to promote passage of iris epithelial cells through the requisite number of cell cycles which will then allow them to redifferentiate as lens fiber cells (Yamada, in: Cell Biology of the Eye. Academic Press, New York, 1982), we undertook testing of the effects of eye-derived mitogenic substances, as well as other mitogens, on regeneration of lens from iris in organ culture. We have previously defined a critical period for the retinal influence in vivo and in vitro, and have shown that crude extracts of retina can enhance regeneration of lenses in culture (Connelly et al., J. Exp. Zool., 240:343-351, 1986). In this paper, we report on the lens regeneration enhancing activity (LRA) of more highly purified fractions of the retinal extracts. Heparin-sepharose chromatography of the crude retinal extract yields three fractions (Courty et al., Biochemie 67:265-269, 1985) called EDGF I, II, and III. EDGF I and II have affinity for heparin, while EDGF III does not. In our bioassay, LRA appears only in the EDGF III fraction. Dialysis of EDGF III against 0.1 N acetic acid yields a fraction which has affinity for cibacron blue sepharose (eluting at 2.15 M salt) and also has significant LRA. Because insulin at high doses has a marginal effect on lens regeneration in culture (Williams and McGlinn, Am. Zool. 19:923, 1979; Connelly, Differentiation 16:85-91, 1980), we tested IGF-I. Because of the putative neurotrophic effects of transferrin (Tf) (Mescher and Munaim, J. Exp. Zool., 230:485-490, 1986), we tested Tf for its ability to enhance regeneration of the lens in culture. IGF-I seems to have an enhancing effect on lens regeneration; Tf does not.
成年蝾螈（绿红东美螈）摘除眼球晶状体后，会发生一系列细胞事件，这些事件会导致色素性虹膜上皮细胞在背侧瞳孔边缘通过细胞类型转换再生出新的晶状体（山田，《发育生物学当前主题》2:247 - 283，1967年）。在色素脱失以及进行五到七次细胞分裂后，虹膜上皮细胞重新分化为晶状体纤维细胞并合成晶状体蛋白（山田，《发育生物学当前主题》2:247 - 283，1967年）。这一过程在体内（斯通，《解剖学记录》131:151 - 172，1958年；雷耶，《发育生物学》14:214 - 225，1966年）和体外（山田等人，《分化》1:65 - 82，1973年）都依赖于神经视网膜。基于神经视网膜的作用是促进虹膜上皮细胞通过必要数量的细胞周期，从而使其能够重新分化为晶状体纤维细胞这一假设（山田，载于《眼的细胞生物学》。学术出版社，纽约市，1982年），我们对眼源性有丝分裂原物质以及其他有丝分裂原对器官培养中虹膜晶状体再生的影响进行了测试。我们之前已经确定了体内和体外视网膜影响的关键时期，并且已经表明视网膜粗提物可以增强培养中晶状体的再生（康奈利等人，《实验动物学杂志》，240:343 - 351，1986年）。在本文中，我们报告了视网膜提取物更高纯度组分的晶状体再生增强活性（LRA）。视网膜粗提物经肝素 - 琼脂糖层析产生三个组分（库尔蒂等人，《生物化学》67:265 - 269，1985年），称为EDGF I、II和III。EDGF I和II对肝素有亲和力，而EDGF III没有。在我们的生物测定中，LRA仅出现在EDGF III组分中。用0.1 N乙酸对EDGF III进行透析得到一个对汽巴克隆蓝琼脂糖有亲和力（在2.15 M盐浓度下洗脱）且也具有显著LRA的组分。由于高剂量胰岛素对培养中晶状体再生有轻微影响（威廉姆斯和麦格林，《美国动物学杂志》19:923，1979年；康奈利，《分化》16:85 - 91，1980年），我们测试了IGF - I。由于转铁蛋白（Tf）具有假定的神经营养作用（梅舍尔和穆奈姆，《实验动物学杂志》，2:485 - 490，），我们测试了Tf增强培养中晶状体再生的能力。IGF - I似乎对晶状体再生有增强作用；Tf则没有。 1986年
