BIOLOGY AND FUNCTION OF CD44 ISOFORMS

CD44是一种广泛表达的细胞表面分子，其 至少有两种异构体。第一种是一种80-9okD的糖蛋白，在 造血细胞以及成纤维细胞、神经细胞和一些 上皮细胞系。此表单，它最近显示为绑定 透明质酸，将被称为CD44H。第二个亚型是15okD 糖蛋白在上皮细胞亚群中表达，并将 称为CD44E。CD44E的配体目前尚不清楚。CD44H 已被证明可以调节细胞与细胞和细胞与底物的黏附，并已 因此牵涉到生物学的几个领域，包括 免疫反应、细胞生长、肿瘤的发展和转移。在 工作中，我们建议研究这两种CD44亚型的功能和生物学。 我们的工作将集中在阐明CD44H和CD44E的作用 在体内肿瘤生长和肿瘤迁移模式的确定方面。 最近分离的编码这两种异构体的cDNA克隆将被用来创建 人和小鼠细胞系中稳定的转染体。中的转染体 人类和小鼠细胞系。转染体将被注射到裸体体内 并对小鼠的致瘤潜力进行评估。稳定的转染体 用截短的胞质结构域表达两种异构体中的任何一种 将用于确定CD44介导的信号转导的作用 肿瘤的发生以及生理细胞功能。可溶形式 将创建并用于识别和分离CD44H和CD44E 每种异构体的特异性配体和阻断转染体诱导的肿瘤 生长和转移。一组单抗的制备 对这两种异构体进行比对，可以确定它们的组织 成体和发育中组织的分布、表位定位和 配基结合部位的鉴定。基因的定点突变 CD44H的胞外区将决定所需的氨基酸序列 用于与透明质酸的相互作用。预计这些方法 将阐明这两种异构体的生理功能以及 它们对肿瘤生长的影响。理解这些因素的作用 调节肿瘤生长的分子可能具有重要的临床意义 这意味着什么。

CD44 is a broadly expressed cell surface molecule of which there are at least two isoforms. The first is an 80-9OkD glycoprotein expressed in hematopoietic cells and also in fibroblasts, neural cells and some epithelial cell lines. This form, which has recently been shown to bind hyaluronate, will be referred to as CD44H. The second isoform is a l5OkD glycoprotein expressed in a subpopulation of epithelial cells and will be referred to as CD44E. The ligands of CD44E are presently unknown. CD44H has been shown to mediate cell-cell and cell-substrate adhesion and has therefore been implicated in several sectors of biology, including the immune response, cellular growth, tumor development and metastasis. In the work, we propose to study the function and biology of both CD44 isoforms. Our efforts will be concentrated on elucidating the role of CD44H and CD44E in tumor growth in vivo and determination of patterns of tumor migration. Recently isolated cDNA clones encoding both isoforms will be used to create stable transfectants in human and murine cell lines. The transfectants in human and murine cell lines. The transfectants will be injected into nude mice and assessed for tumorigenic potential. Stable transfectants expressing either of the two isoforms with truncated cytoplasmic domains will be used to determine the role of signal transduction in CD44-mediated tumorigenesis as well as in physiologic cellular functions. Soluble forms of both CD44H and CD44E will be created and used to identify and isolate ligands specific for each isoform and to block transfectant-induced tumor growth and metastasis. Generation of a battery of monoclonal antibodies against both isoforms will allow the determination of their tissue distribution in adult and developing tissues, epitope mapping and identification of ligand binding sites. Site specific mutagenesis of the extracellular domain of CD44H will determine amino acid sequences required for interaction with hyaluronate. It is anticipated that these approaches will elucidate the physiologic function of the two isoforms as well as their influence on tumor growth. Understanding of the role of these molecules in tumor growth regulation may have important clinical implications.