REGULATION OF ACINAR CELL PROLIFERATION

长期注射β-肾上腺素能激动剂异丙肾上腺素， 除了细胞肥大和增生外， 大鼠和小鼠腮腺中的蛋白质合成。 中 生化变化是比活性和地形的增加， 一种通常被认为是高尔基体膜标记酶4 β- 半乳糖基转移酶（Gal Tase）。 酶活性的类似变化， 通过引入饮食和激素， 导致功能性腺体活动增加的变化， 增生 上调和表面定位的重要性 在实验中， 这种酶被证明可以严重抑制腮腺肥大 和增生。 已分离出一个cDNA克隆， 特异性调节Gal Tase的细胞表面外观， 因此腺泡细胞生长。 部分cDNA序列分析 表明与参与细胞分裂的一类酶同源。 的 命名为GTA（Gal Tase activator）的克隆是Ca+2/钙调蛋白依赖性的 丝氨酸蛋白激酶，其在腮腺细胞中响应于 异丙肾上腺素 激酶的底物高尔基体定位于Gal Tase， 磷酸化后，靶向质膜。 许多报告 已经表明，细胞表面半乳糖转移酶活性的改变可能是 参与细胞粘附、分化和肿瘤发生。 因此我们 相信GTA基因调控的研究对于 了解腮腺和其他组织的生长控制， 表面半乳糖苷酶 为了实现这一点，GTA cDNA将用于分离 将分析染色体序列以用于组织调节 序列以及内含子和外显子结构。 GTA cDNA可以让我们 在分子水平上研究基因表达和 Gal Tase细胞表面定位对腺泡细胞生长影响 和体外培养。 将分离GTA蛋白并进行生化分析; 将纯化的蛋白用于抗体生产和免疫组织学 问题研究 最后，我们将继续研究 β-受体激动剂信号转导中的细胞内事件 GTA的表达，以及Gal Tase在细胞核中的作用。 质膜在使腺泡细胞增殖的信号永久化中起作用。 这些调查结果最终将用于评价一般临时人员的贡献 人半乳糖基转移酶的表达和介导的细胞增殖 口腔的病理，特别是口腔的疾病， 涉及组织肥大和增生的唾液腺。

Chronic injections of the beta-adrenergic agonist, isoproterenol, produce in addition to cell hypertrophy and hyperplasia, biochemical alterations in protein synthesis in the rat and mouse parotid gland. Among the biochemical changes is an increase in specific activity and topography for an enzyme normally thought of as a Golgi membrane marker enzyme 4beta- galactosyltransferase (Gal Tase). A similar change in enzyme activity and localization is observed with the introduction of dietary and hormonal changes that result in an increased functional gland activity and resulting hyperplasia. The importance of the up-regulation and surface localization of Gal Tase became apparent in experiments in which agents that interact with this enzyme were shown to severely inhibit parotid gland hypertrophy and hyperplasia in vivo or in vitro. A cDNA clone has been isolated which specifically modulates the cell surface appearance of Gal Tase and therefore acinar cell growth. Sequence analysis of a partial cDNA indicated homology to a class of enzymes involved in cell division. The clone designated GTA (Gal Tase activator) is a Ca+2/calmodulin dependent serine protein kinase which is induced in parotid cells in response to isoproterenol. The substrate of the kinase Golgi localized Gal Tase, which upon phosphorylation, is targeted to the plasma membrane. Numerous reports have shown that alteration of cell surface Gal Tase activity might be involved in cell adhesion, differentiation and tumorogenesis. We therefore believe that studies of the regulation of the GTA gene are crucial to understanding growth control of parotid and other tissues regulated by surface Gal Tase. To accomplish this, the GTA cDNA will be used to isolate chromosomal sequences which will be analyzed for organization of regulatory sequences as well as intron and exon structure. The GTA cDNA will allow us to examine at the molecular level, the effects that gene expression and cell surface localization of Gal Tase have on acinar cell growth in vivo and in vitro. The GTA protein will be isolated and biochemically analyzed; using the purified protein for antibody production and immunohistological studies. Finally, we will continue to investigate the sequence of intracellular events involved in the signal transduction from beta-agonist to the nucleus causing expression of GTA, and the action of Gal Tase in the plasma membrane in perpetuating the signal for acinar cell proliferation. These findings will ultimately be used to evaluate the contribution of GTA expression and galactosyltransferase-mediated cell proliferation in human pathologies of the oral cavity, and in particular, disorders of the salivary glands involving tissue hypertrophy and hyperplasia.