CELL SUBSTRATE INTERACTION IN CRANIOFACIAL MORPHOGENESIS

胚胎形态发生，以及头部和颈部的发育， 特别是，是复杂的细胞迁移的结果， 几乎所有的骨骼肌肉和腺体结构。 的 对这些细胞迁移的基础机制知之甚少， 尽管他们是许多常见的先天性 畸形 最近，我们已经确定了一种新的酶促机制， 基底层基质上的细胞迁移。 结果表明，细胞 表面半乳糖基转移酶（GalTase）识别并结合其 基底层中的适当基质促进细胞：基质 粘附和随后的迁移。 细胞迁移可以被抑制， 用选择性抑制或刺激的试剂刺激， 分别为表面GalTase活性。 有趣的是，这些试剂具有 对纤连蛋白底物上的细胞迁移无影响，显示底物 GalTase作用的特异性。 在本提案中，我们将定义 表面GalTase在迁移过程中的受体功能，并确定其 基底层中的互补配体。 为了完成这些研究，我们将检查单特异性 抗GalTase IgG对体外细胞迁移的影响 印刷受体. 实验将定义定位。营业额及 迁移过程中表面GalTase的再循环，以及其与 到细胞骨架。 将抗GalTase IgG注射到迁移的 颅神经嵴细胞干扰颅面形态发生的途径 in vivo. 基底层中的GalTase底物将通过 常规生化技术。 将在inert上分析迁移 用纯化的GalTase底物衍生的底物， 酶改性的。 因为表面的半乳糖苷酶 层粘连蛋白，我们将研究GalTase和层粘连蛋白之间的关系， 受体的 作为一个独立的屏幕，细胞：基质相互作用将是 用光活化的异双功能交联剂鉴定。 最后， 我们将尝试纠正致命的迁移缺陷T/T突变， 体外和体内通过抑制过量的表面GalTase活性， 正常水平。 这些结果将使我们能够确定一个特定的分子 某些细胞与基质在形态发生过程中相互作用机制， 有助于我们了解先天性畸形

Embryonic morphogenesis, and development of the head and neck in particular, is the result of sophisticated cellular migrations which form virtually all of the skeletal, muscular and glandular structures. The mechanisms that underlie these cell migrations are poorly understood, despite the fact that they are responsible for many common congenital malformations. Recently, we have identified a novel enzymatic mechanism for mesenchymal cell migration on basal lamina substrates. Results suggest that cell surface galactosyltransferase (GalTase) recognizes and binds its appropriate substrates in the basal lamina facilitating cell:substrate adhesion and subsequent migration. Cell migration can be inhibited or stimulated with reagents that selectively inhibit or stimulate, respectively, surface GalTase activity. Interestingly, these reagents have no effect on cell migration on fibronectin substrates, showing substrate specificity of GalTase action. In this proposal, we will define the receptor function of surface GalTase during migration and identify its complementary ligand in the basal lamina. To accomplish these studies, we will examine the effects of monospecific anti-GalTase IgG on cell migration in vitro on a variety of defined substrates. Experiments will define the localization., turnover and recycling of surface GalTase during migration, as well as its relationship to the cytoskeleton. Anti-GalTase IgG will be injected into the migratory pathway of cranial neural crest cells to perturb craniofacial morphogenesis in vivo. The GalTase substrates in the basal lamina will be identified by conventional biochemical techniques. Migration will be analyzed on inert substrates derivatized with purified GalTase substrates that have been enzymatically modified. Since the surface GalTase appears to recognize laminin, we will examine the relationship between GalTase and the laminin receptor. As an independent screen, cell:matrix interactions will be identified with photoactivated heterobifunctional crosslinkers. Finally, we will attempt to correct the lethal migration-deficient T/T mutation in vitro and in vivo by inhibiting the excess surface GalTase activity down to normal levels. These results will enable us to define a specific molecular mechanism for some cell:matrix interactions during morphogenesis and will aid in our understanding of congenital malformations.