CELL-CELL SIGNALING IN VISUAL DEVELOPMENT

结合细胞表面受体的多肽因子是强大的 细胞间通讯的介质，并在 生理学和疾病。 存在大量身份不明的 “孤儿”的鉴定暗示了多肽因子 受体”，似乎是细胞表面受体，但对于 配体未知。 这些配体的鉴定是关键的一步 了解孤儿受体的生物学， 为我们理解细胞间相互作用提供了重要的进展 梗概. 此外，许多配体将是用于合成的良好候选物。 治疗用途。 我们最近确定了孤儿受体酪氨酸的配体（KL） 由c-kit原癌基因编码的激酶通过一般适用的 方法：将受体胞外结构域基因融合到 胎盘碱性磷酸酶，产生可溶性受体亲和力 带有酶标记的试剂，可以容易且灵敏地追踪。 本提案的主要目标是开发我们的可溶性 受体亲和性的方法，并将其应用于识别配体 一种孤儿受体蛋白酪氨酸磷酸酶 虽然孤儿 受体酪氨酸磷酸酶正被快速鉴定， 关于它们的配体的信息很少。 尽管如此， 受体参与酪氨酸的控制 磷酸化表明配体很可能具有潜在的 生物效应。 除了我们对磷酸酶的研究外，我们还将进行以下实验： c-kit受体与其最近鉴定的配体的相互作用 KL. 这些实验有两个目标。 第一个将是发展 可以应用于受体酪氨酸磷酸酶和其它 孤儿受体 第二个目标是同时获得有用的 c-kit和KL的生物学信息。 可溶性的研究 受体融合蛋白的设计提供了重要的新信息 对KL多肽的分布和亚型的影响， 存在于组织中。 我们还将执行一个结构/功能 分析c-kit与KL的相互作用。 这将使我们能够绘制出 功能域，并研究功能 配体-受体结合，细胞-细胞粘附， 增殖和迁移，所有这些都可以由KL介导。

Polypeptide factors that bind to cell surface receptors are powerful mediators of cell-cell communication and have important roles in physiology and disease. The existence of a large number of unidentified polypeptide factors is implied by the identification of "orphan receptors" which appear to be cell surface receptors but for which the ligands are unknown. Identification of these ligands is a critical step in understanding the biology of the orphan receptors, and will also provide important advances in our understanding of cell-cell interaction in general. Moreover, many of the ligands will be good candidates for therapeutic use. We recently identified the ligand (KL) of the orphan receptor tyrosine kinase encoded by the c-kit proto-oncogene by a generally applicable approach: the receptor extracellular domain was genetically fused to placental alkaline phosphatase, producing a soluble receptor affinity reagent with an enzyme tag that could be easily and sensitively traced. The major objective of the present proposal is to develop our soluble receptor affinity approach further, and apply it to identify the ligand of an orphan receptor protein tyrosine phosphatase. Although orphan receptor tyrosine phosphatases are being identified at a rapid rate, little information is available on any of their ligands. Nonetheless, the involvement of the receptors in the control of tyrosine phosphorylation indicates that the ligands are likely to have potent biological effects. In addition to our work on phosphatases, we will perform experiments on the interaction of the c-kit receptor and its recently identified ligand KL. These experiments will have two goals. The first will be to develop methods that can be applied to receptor tyrosine phosphatases and other orphan receptors. The second goal will be to concurrently derive useful information on the biology of c-kit and KL. Studies with the soluble receptor fusion protein are designed to provide important new information on the distribution and the isoforms of the KL polypeptide that are present in tissues. We will also carry out a structure / function analysis of the interaction of c-kit and KL. This will allow us to map functional domains and also to investigate the functional interrelationships between ligand-receptor binding, cell-cell adhesion, proliferation and migration, all of which may be mediated by KL.