Regulation of B1 Integrin Glycosylation by RAS

描述：（由申请人提供）整合素粘附受体调节许多 重要的细胞过程，包括细胞增殖、细胞周期等。 迁移/侵袭、细胞分化和贴壁依赖性生长。 任何这些区域的整合素功能改变都能促进肿瘤发生 和/或转移，因此，密集的研究集中在 了解这些受体的调节。初步研究报告 在该提议中描述了一种新整联蛋白调节机制。是 显示致癌Ras表达导致B1整联蛋白获得5-6倍的 α 2 -6连接的唾液酸残基的丰度更高。一种酶， 这种连接，ST 6 Ga 1 I，在肿瘤组织中上调，并且增加了ST 6 Ga 1 I， 与细胞的侵袭性有关。因此，ST 6 Ga 1 I的增加 活性长期以来与癌症进展有关。尽管有这些 研究结果表明，这种酶靶向的特定分子种类还没有被发现。 鉴定提出了一个中心假设，即致癌ras增加了 本发明还涉及ST 6 Ga 1 I唾液酸转移酶的表达和/或功能，并且本发明涉及ST 6 Ga 1 I唾液酸转移酶的表达和/或功能。 然后，酶作用于β 1整联蛋白以增加α 2 -6唾液酸的数量 残基反过来，β 1整合素的α 2 -6唾液酸化增加诱导β 1整合素的α 2 -6唾液酸化。 导致功能改变的构象变化。广泛的，长期的 这项研究的目的是证明变异的糖基化 代表B1整联蛋白调节的重要机制，而且， 致癌ras诱导的变异糖型表达有助于 肿瘤发生和/或转移。这些目标将通过以下方式实现：1） 确定ras介导的B1整合素碳水化合物结构和 ST 6 Ga 1 I活性（目的1）为了阐明ras通过其改变ST 6 Ga 1 I活性的机制， 整合素糖基化，糖结构和N-连接的位点 将鉴定糖基化，并且将鉴定ST 6 Ga 1 I的活性/表达。 被评价。2)确定糖基化改变在以下方面起因果作用： 修饰整联蛋白功能（目标2）整联蛋白α 2 -6唾液酸化的水平将是 直接改变并检查整联蛋白功能。此外，细胞 将使用诱导型ras构建体来确定 改变的糖型在时间上与改变的功能相关。第三章 确定改变的131整合素糖基化是否有助于癌症 进展（目标3）将检查过表达ST 6 Ga 1 I的细胞的 裸细胞中的锚定非依赖性生长、迁移/侵袭和肿瘤形成 小鼠此外，将测定胰腺肿瘤标本中的 变体B1糖型。

DESCRIPTION: (provided by applicant) Integrin adhesion receptors regulate many important cellular processes including cell proliferation, cell migration/invasion, cell differentiation and anchorage-dependent growth. Altered integrin function in any of these areas can promote tumorigenesis and/or metastasis, and hence, intense investigation has centered on understanding the regulation of these receptors. Preliminary studies presented in this proposal describe a novel mechanism for integrin regulation. It is shown that expression of oncogenic ras cause Bl integrins to acquire a 5-6-fold greater abundance of a2-6 linked sialic acid residues. The enzyme that directs this linkage, ST6Ga1 I, is upregulated in tumor tissues, and increased ST6Ga1 I is associated with cell invasiveness. Accordingly, increases in ST6Ga1 I activity have long been implicated in cancer progression. Despite these findings, the specific molecular species targeted by this enzyme have not been identified. A central hypothesis is proposed that oncogenic ras increases the expression and/or function of the ST6Ga1 I sialyltransferase, and that this enzyme then acts on the, B1 integrin to increase the number of a2-6 sialic acid residues. In turn, increased a2-6 sialylation of the 31 integrin induces a conformational change that leads to altered function. The broad, long term goals of the proposed research are to demonstrate that variant glycosylation represents an important mechanism for B1 integrin regulation and further, that oncogenic ras-induced expression of a variant glycoform contributes to tumorigenesis and/or metastasis. These goals will be accomplished by: 1) Defining the ras-mediated changes in B1 integrin carbohydrate structure and in ST6Ga1 I activity (Aim 1) To elucidate the mechanism by which ras alters integrin glycosylation, the carbohydrate structures and sites of N-linked glycosylation will be identified, and the activity/expression of ST6Ga1 I will be evaluated. 2) Establishing that altered glycosylation plays a causal role in modifying integrin function (Aim 2) Levels of integrin a2-6 sialylation will be directly altered and integrin function will be examined. In addition, cells with an inducible ras construct will be used to determine whether expression of an altered glycoform is temporally correlated with altered function. 3) Determining whether altered 131 integrin glycosylation contributes to cancer progression (Aim 3) Cells that overexpress ST6Ga1 I will be examined for anchorage-independent growth, migration/invasion, and tumor formation in nude mice. In addition, pancreatic tumor specimens will be assayed for expression of a variant B1 glycoform.