BIOLOGY AND FUNCTION OF CD44 ISOFORMS

CD 44是一种广泛表达的细胞表面分子， 至少两种异构体。 第一种是80- 90 kD糖蛋白，在大肠杆菌中表达， 造血细胞以及成纤维细胞、神经细胞和一些 上皮细胞系 这种形式，最近被证明是结合 透明质酸盐，将被称为CD 44 H。 第二种亚型是150 kD 糖蛋白在上皮细胞亚群中表达，并且将被 称为CD 44 E。 CD 44 E的配体目前尚不清楚。 CD44h 已显示介导细胞-细胞和细胞-基质粘附， 因此被牵连在生物学的几个部门，包括 免疫应答、细胞生长、肿瘤发展和转移。 在 工作，我们建议研究这两个CD 44亚型的功能和生物学。 我们的努力将集中在阐明CD 44 H和CD 44 E的作用， 在体内肿瘤生长和肿瘤迁移模式的测定中。 最近分离的编码两种同种型的cDNA克隆将用于产生 稳定的转染子。 转染子在 人和鼠细胞系。将转染子注射到裸鼠体内， 小鼠并评估肿瘤发生潜力。 稳定转染子 表达具有截短胞质结构域的两种同种型中的任一种 将用于确定CD 44介导的信号转导中的作用。 肿瘤发生以及生理细胞功能。 可溶形式 CD 44 H和CD 44 E的基因将被创建并用于识别和分离 对每种同种型特异的配体并阻断转染诱导的肿瘤 生长和转移。 一系列单克隆抗体的产生 将允许确定它们的组织 在成人和发育组织中的分布，表位作图和 配体结合位点的鉴定。 位点特异性诱变 CD 44 H的胞外结构域将决定所需的氨基酸序列 与透明质酸相互作用。 预计这些方法 将阐明这两种亚型的生理功能， 对肿瘤生长的影响。 理解这些作用 肿瘤生长调节分子可能具有重要的临床意义 影响

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.