MELANOMA GANGLIOSIDES AND INTEGRIN FUNCTION

某些肿瘤，包括黑素瘤和神经元肿瘤，以及 胚胎神经组织，表达神经节苷脂（GD2，GD3和9OAcGD3），发现 在正常成人组织中仅存在低水平，或根本不存在，这意味着 在这些细胞和组织的表型特性上。 的 所提出的实验集中在理解某些生物 神经节苷脂在正常和转化细胞中的功能。 许多研究 间接表明膜蛋白之间相互作用， 神经节苷脂存在于同一双层中，并且这些 相互作用调节这些蛋白质的功能。 拟议 实验直接在两个独立但 互补系统。 第一种是基于其他人的工作， 黑色素瘤上发现的玻连蛋白受体（VNr） 细胞和某些黑素瘤神经节苷脂。 使用重构的脂质体 从纯化的VNr和神经节苷脂，功能和生化方面， 的VNr神经节苷脂协会将直接研究。 实验方法，表达克隆技术将用于 克隆神经节苷脂生物合成关键酶的cDNA。 然后将这些克隆用于操纵 不同的神经节苷脂。 预期的方法 需要从仅表达简单神经节苷脂的细胞系开始 结构，然后用编码该结构的cDNA转染。 糖基转移酶（或控制它的调节蛋白）， 在这个神经节苷脂上附着一个糖残基， 在生物合成途径中。 在这种方式下，神经节苷脂的档案， 可以以迄今为止不可能方式操作单个细胞系。 对细胞整合素分子的功能研究将是 并与其神经节苷脂谱相关。 这些结果将 与所述的体外重构系统直接相当 以上 这种通用方法可以适用于广泛的研究 上面提到的三种神经节苷脂只是许多例子中的三种 糖脂和糖蛋白的异常糖基化， 恶性转化 这些研究的长期目标是 了解酶的基础，调节和功能后果 这些变化，希望更好地了解生物学 正常组织和恶性组织。

Certain tumors, including melanomas and neuronal tumors, as well as embryonic neural tissue, express gangliosides (GD2, GD3, and 9OAcGD3) found only in low levels, or not at all, in normal adult tissue, implying a role for them in the phenotypic properties of these cells and tissues. The experiments proposed are focused on understanding certain biological function(s) of gangliosides in normal and transformed cells. Many studies indirectly indicate that interactions between membrane proteins and gangliosides present in the same bilayer do occur, and that these interactions regulate the function of these proteins. The proposed experiments explore this concept directly in two independent but complementary systems. The first is based on the work of others indicating an association between the vitronectin receptor (VNr) found on melanoma cells and certain melanoma gangliosides. Using liposomes reconstituted from purified VNr and gangliosides, the functional and biochemical aspects of VNr-ganglioside association will be studied directly.In a parallel experimental approach, expression cloning techniques will be utilized to clone the cDNA's of key enzymes involved in ganglioside biosynthesis. These clones will then be utilized to manipulate the expression of different gangliosides on the cell's surface. The anticipated approach entails starting with a cell line which expresses only a simple ganglioside structure, and then transfection with the cDNA encoding for the glycosyltransferase (or regulatory protein(s) which control it) which attaches a sugar residue to this ganglioside, building the next ganglioside in the biosynthetic pathway. In this fashion, the ganglioside profile of a single cell line could be manipulated in a fashion heretofore not possible. Functional studies on the cell's integrin molecule(s) would then be performed and correlated with its ganglioside profile. These results would be directly comparable with the in vitro reconstituted system described above. This general approach can be adapted to the study a wide range of proteins.The three gangliosides noted above are just three of many examples of the aberrant glycosylation of glycolipids and glycoproteins found with malignant transformation. The longterm objectives of these studies is understanding the enzymatic basis, regulation, and functional consequences of these changes, with the hope of a greater understanding of the biology of both normal and malignant tissues.