FIBROBLAST AGING AND PROGRAMMED CELL DEATH

生物学研究中最令人着迷的领域之一是 调节衰老过程的机制 这一主题 一项建议表明，一个明确的遗传程序控制着人类的基因。 细胞衰老时细胞复制的不可逆终止。 我们 假设正常的成纤维细胞注定要衰老， 不扩散是导致死亡的最终计划的最初部分。 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，并且与 在静止期出现短暂的生长停滞。 这里我们假设 特定基因表达程序被激活，使细胞成为 非增殖和衰老。 我们研究的第一步沿着这个 行是识别基因或其产物唯一存在于 衰老细胞和缺席在其年轻的生长或非生长 同行 我们已经成功地确定了第一个这样的例子， 基因产物，末端蛋白。 终止子的标识为 通过实验来验证我们的假设：（1）表征 通过免疫组织化学研究确定组织中的终末蛋白存在;（2）评估 在组织中定性和定量地表达终末蛋白， 从年轻，中年和老年动物;（3）表征细胞 免疫胶体金电镜鉴别终末蛋白阳性颗粒 研究和组织化学酶测定;（4）表征可能的 终末蛋白表达调控的生化机制;（5）终末蛋白的纯化 多肽，对蛋白质进行测序并产生大分子探针;以及 (6)进行编码以下的cDNA克隆的初始克隆和测序： 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 关于端蛋白基因的表达是如何控制的， 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， 成纤维细胞衰老或终末分化，最后一部分长 为细胞凋亡的最终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.