CELL SURFACE AND MATRIX PROTEINS IN LIMB DEVELOPMENT

在脊椎动物胚胎发育过程中出现的形式和图案是因为 细胞在特定的空间和时间限制下分化 通过相互的组织相互作用。这项研究的核心是 假设这种相互作用部分是由独特的 细胞表面和胞外蛋白。我们计划检验这一假设 使用发育中的鸟类肢体。具体地说，这项研究的目的是 鉴定和鉴定细胞外和细胞表面蛋白 (I)局限于瓣芽的特定区域，(Ii)与 它们的出现时间与关键的形态发生事件和(Iii) 受破坏肢体形态发生的突变的影响。相遇的蛋白质 这些标准很可能是形态发生的控制因素。 细胞表面和基质蛋白将在(1)中识别和比较。 未定植、增殖性肢体中胚层与近端分化 正常胚胎和talpid2突变体中的中胚层 多合趾肢体，(2)诱导活跃的顶端外胚层脊vs。 正常胚胎的非脊外胚层和暂时性肢体的外胚层 不能形成顶脊的无肢突变体的芽。蛋白质 将在体内用35S-蛋氨酸、~3H-岩藻糖或 ~(32)P-正磷酸盐和细胞表面及基质蛋白和糖蛋白 将在体外选择性地标记125I/loodogen或 ~3H-硼氢化物/高碘酸根。细胞外、细胞表面和质膜 蛋白质将通过选择性的酶消化进一步区分 完整组织，通过选择性增溶和质膜 与世隔绝。我们相信无肢和健谈的突变体提供了 用于分析遗传性肢体缺陷的优秀模型系统 高等生物体和细胞表面的特性以及 细胞外蛋白在正常和突变肢体发育中都将 显著增强我们对组织分子基础的理解 互动。我们希望这些研究将有助于更好地 对人类先天性肢体缺陷的认识。

Form and pattern arise during vertebrate embryogenesis because groups of cells differentiate under specific spatial and temporal constraints imposed by reciprocal tissue interactions. Central to this research is the hypothesis that such interactions are mediated in part by unique sets of cell surface and extracellular proteins. We plan to test this hypothesis using the developing avian limb. Specifically, the aim of this research is to identify and characterize extracellular and cell surface proteins that are (i) restricted to specific regions of the limb bud, (ii) correlated in the time of their appearance with key morphogenetic events and (iii) affected by mutations that disrupt limb morphogenesis. Proteins that meet these criteria are very likely to be controlling factors in morphogenesis. Cell surface and matrix proteins will be identified and compared in (1) uncommitted, proliferating limb mesoderm vs. differentiation proximal mesoderm in normal embryos and in talpid2 mutants which form polysyndactylous limbs, (2) inductively active apical extodermal ridge vs. non-ridge extoderm from normal embryos and ectoderm from the transient limb buds of limbless mutants which fails to form an apical ridge. Proteins will be labeled in vivo with 35S-methionine, 3H-fucose or 32p-orthophosphate and cell surface and matrix proteins and glycoproteins will be selectively labeled in vitro with 125I/lodogen or 3H-borohydride/periodate. Extracellular, cell surface and plasma membrane proteins will be further distinguished by selective enzymatic digestion of intact tissues, by selective solubilization and by plasma membrane isolation. We believe that the limbless and talpid mutants provide excellent model systems for the analysis of inherited limb defects in higher organisms and that the characterization of cell surface and extracellular proteins in both normal and mutant limb development will significantly enhance our understanding of the molecular bases of tissue interactions. We hope that these studies will conribute to a better understanding of human congenital limb defects.