FIBROBLAST AGING AND PROGRAMMED CELL DEATH

生物学研究中最令人着迷的领域之一是 衰老的调节机制。这次会议的主题是 一项提议表明，一个明确的遗传程序控制着 随着细胞衰老，细胞复制不可逆转地终止。我们 假设正常的成纤维细胞注定会衰老 不扩散作为导致死亡的最终计划的初始部分。 因此衰老类似于终末分化，可能是一种状态， 在每个细胞中都是强制性的和占主导地位的，与 在静止状态下出现短暂的生长停滞。在这里，我们假设一个 特定的基因表达程序被激活，使细胞成为 非增殖性的和衰老的。我们沿着这个方向进行研究的第一步 品系是鉴定基因(S)或其产物(S)唯一存在的 衰老的细胞，在幼年生长或不生长时不存在 对口单位。我们已经成功地确定了第一个这样的例子 基因产物，终止素。终端的标识提供了一个句柄 通过执行实验来测试我们的假设：(1)表征 通过免疫组织化学研究终止素的存在；(2)评估 终止素在来源组织中的定性和定量表达 来自幼年、中年和老年动物；(3)表征细胞 终止素阳性颗粒的免疫金超微结构鉴定 研究和组织化学酶分析；(4)表征可能 调节终末蛋白表达的生化机制；(5)纯化终末蛋白 多肽，对蛋白质进行测序并产生大分子探针；以及 (6)进行编码基因的cDNA克隆的初步克隆和测序 终末蛋白。这些实验的结果将为我们提供 调查下一系列问题所需的信息和工具 终止素基因表达的调控及其作用 与衰老过程有关的蛋白质。最终，它将揭示 关于细胞如何永久关闭复制的机制，如 成纤维细胞衰老或终末分化，最后一段长 为最终的细胞凋亡事件做准备的生理过程， 每个细胞的命运。

What remains one of the most fascinating areas in biological research is the mechanism regulating the events of aging. The main theme of this proposal suggests that a defined genetic program is in control of the irreversible termination of cell replication as cells become senescent. We have hypothesized that normal fibroblasts are destined for senescent nonproliferation as the initial part of a final program leading to death. Therefore senescence similar to terminal differentiation, may be a state, obligatory and dominant in every cell, and distinctly different from the transient growth-arrest seen in quiescence. Here we hypothesize that a specific program of gene expression sis activated for cells to become nonproliferative and senescent. The first step of our research along this line is to identify gene(s) or their product(s) uniquely present in senescent cells and absent in their young growing or nongrowing counterparts. We have succeeded in identifying a first example of such a gene product, terminin. Identification of terminin provides a handle to test our hypothesis by performing experiments to: (1) characterize terminin presence in tissues by immunohistochemical studies; (2) assess terminin expression qualitatively and quantitatively in tissues derived from young, middle-aged, and old animals; (3) characterize the cellular identity of terminin-positive granules by immunogold ultrastructural studies and histochemical enzymatic assays; (4) characterize possible biochemical mechanisms regulating terminin expression; (5) purify terminin polypeptides, sequence the protein and generate macromolecular probes; and (6) carry out initial cloning and sequencing of cDNA clones encoding for terminin proteins. Results of these experiments will provide us the necessary information and tools to investigate the next series of questions on how terminin gene expression is controlled and what is the function of the protein relating to the aging process. Ultimately, it will shed light on the mechanism of how cells turn off replication permanently as seen in fibroblasts senescence or terminal differentiation, the last part of a long physiological process preparing for the final event of apoptosis, the destiny of every cell.