Head M W, Triplett E L, Ede D A, Clayton R M
Institute of Cell, Animal and Population Biology, University of Edinburgh, United Kingdom.
Int J Dev Biol. 1992 Sep;36(3):363-72.
Embryonic lens fiber cell differentiation in the chick is marked by the accumulation of delta-crystallin protein. The levels of delta-crystallin RNA are shown here to rise dramatically in the cells of the posterior lens pit prior to their elongation and differentiation as lens fibers. This increase correlates with regional proximity to the underlying optic cup (future retina). This accumulation of delta-crystallin RNA during lens induction operates selectively on the delta 1-crystallin transcripts whereas delta 2-crystallin/argininsosuccinate lyase RNA is detectable at lower levels in all developing ocular tissues throughout this period. The talpid3 mutant forms a flat "bridge" of thickened placode-like cells in the head epithelium between the two lens placodes, and this bridge also accumulates delta 1-crystallin RNA, suggesting that the selective increase in delta 1-crystallin RNA levels over those of delta 2-crystallin represents an early event in cellular commitment to lens fiber differentiation in the chick. The significance of the sequence of temporal changes in inductive sources for lens fiber formation is discussed, and we propose that the role of the optic cup is to provide, bound to its extra-cellular material (ECM), a high local concentration of the same growth factors which act as fiber inducers in the older eye.
鸡胚胎晶状体纤维细胞的分化以δ-晶体蛋白的积累为标志。本文显示，在晶状体后凹的细胞伸长并分化为晶状体纤维之前，δ-晶体蛋白RNA水平急剧上升。这种增加与靠近下方视杯（未来的视网膜）的区域有关。在晶状体诱导过程中，δ-晶体蛋白RNA的这种积累选择性地作用于δ1-晶体蛋白转录本，而在此期间，在所有发育中的眼组织中，δ2-晶体蛋白/精氨琥珀酸裂解酶RNA的水平较低。talpid3突变体在两个晶状体原基之间的头部上皮中形成了一个由增厚的原基样细胞组成的扁平“桥”，并且这个“桥”也积累了δ1-晶体蛋白RNA，这表明δ1-晶体蛋白RNA水平相对于δ2-晶体蛋白的选择性增加代表了鸡细胞向晶状体纤维分化的早期事件。本文讨论了晶状体纤维形成诱导源时间变化序列的意义，我们提出视杯的作用是在其细胞外物质（ECM）中提供高局部浓度的相同生长因子，这些生长因子在成年眼中作为纤维诱导剂起作用。
