GROWTH REGULATION BY A PLASMA MEMBRANE MITOGEN

在这两种细胞的表面都发现了一种促有丝分裂的多肽 成纤维细胞和小鼠肝脏。这项研究的主要目标是 建议是确定这种内源性增长刺激的作用 多肽在正常细胞中的增殖，并对该因子进行纯化。工作 将通过两种不同的方法来提纯该因子。这个 第一个使用标准的生化技术，而第二个涉及 产生抗有丝分裂原的单抗。两个人 途径是相辅相成的；分离出一种单抗将 简化有丝分裂原的生物化学纯化(通过亲和 层析)，并对有丝分裂原进行生化纯化 增加获得单抗的成功机会(通过 提供用于免疫的高度有丝分裂原富集组分)。 一旦获得了有丝分裂原的特定探针，就有可能 研究该因子在细胞增殖中的作用。会是 确定有丝分裂活性是否在 细胞周期的某些部分；如果该因子优先表达 在某一生长阶段；如果用 无论是协同生长因子，还是生长抑制肽，都会改变 膜上有丝分裂因子的表达和/或释放； 如果某些转化系含有和/或分泌大量的 这个因素。最后一点特别令人感兴趣，因为最近 研究发现，内源性生长调节蛋白的过度生产 与转化有关，而且病毒癌基因已经被联系在一起 到促进细胞生长的分子。还将确定是否 当膜结合时或如果膜释放时，该因子是活性的 活动所需的。这些研究应该会产生对 这种有丝分裂原在细胞表面的调节和表达，以及如何 这种调节与细胞生长有关。

A mitogenic peptide has been identified on the surface of both cultured fibroblasts and mouse liver. The primary objectives of this research proposal are to establish the role of this endogenous growth-stimulatory peptide in normal cellular proliferation, and to purify the factor. Work will be initiated on purifying the factor via two separate approaches. The first utilizes standard biochemical techniques, whereas the second involves the generation of a monoclonal antibody against the mitogen. The two pathways are complementary; isolation of a monoclonal antibody will simplify the biochemical purification of the mitogen (through affinity chromatography), and the biochemical purification of the mitogen will increase the chances of success in obtaining a monoclonal antibody (by providing highly mitogen enriched fractions for immunization). Once a specific probe of the mitogen has been obtained it will be possible to study the role of this factor in cellular proliferation. It will be determined if the mitogenic activity is preferentially expressed during a certain part of the cell cycle; if the factor is preferentially expressed during a certain stage of growth; if treatment of quiescent cells with either synergistic growth factors, or growth-inhibitory peptides, alters the expression and/or release of the mitogenic factor from the membrane; and if certain transformed lines contain and/or secrete large quantities of this factor. This last point is of particular interest due to the recent findings that overproduction of endogenous growth regulatory proteins is associated with transformation, and that viral oncogenes have been linked to cellular growth promoting molecules. It will also be determined whether the factor is active while membrane bound, or if membrane release is required for activity. These studies should generate an understanding of the regulation and expression of this mitogen on the cell surface, and how this regulation is related to cell growth.