GROWTH REGULATION BY A PLASMA MEMBRANE MITOGEN

一种促有丝分裂肽已经在两种培养的细胞表面被鉴定出来。 成纤维细胞和小鼠肝脏。 本研究的主要目的 建议是建立这种内源性增长刺激的作用， 肽在正常细胞增殖中的作用，并纯化该因子。 工作 将通过两种不同的方法开始纯化因子。 的 第一种是利用标准的生物化学技术，而第二种则涉及 产生抗有丝分裂原的单克隆抗体。 两 途径是互补的;单克隆抗体的分离将 简化了有丝分裂原的生物化学纯化（通过亲和层析 层析），并且有丝分裂原的生化纯化将 增加获得单克隆抗体的成功机会（通过 提供用于免疫的高度富集有丝分裂原的级分）。 一旦获得了有丝分裂原的特异性探针， 来研究这个因子在细胞增殖中的作用。 将 确定促有丝分裂活性是否在细胞周期中优先表达， 细胞周期的某个部分;如果该因子优先表达 在一定的生长阶段;如果用 无论是协同生长因子，还是生长抑制肽， 促有丝分裂因子从膜的表达和/或释放; 并且如果某些转化株系含有和/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产生是 与转化有关，病毒致癌基因与 到细胞生长促进分子。 还将确定是否 该因子在膜结合时是有活性的，或者如果膜释放是 活动所需。 这些研究应有助于了解 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.