MOLECULAR AND CYTOGENETIC STUDIES OF HUMAN CELL AGING

正常的人类细胞在体外表现出严格的限制分裂 容量 与此相反，肿瘤源性和病毒，致癌物或 辐射转化的细胞可以无限分裂（永生）。 我们 还不了解限制分裂潜力的机制， 正常的人类细胞或产生永生细胞的变化。 然而，从细胞杂交研究中我们发现， 表型由正常细胞生长控制的隐性变化引起。 我们利用这一点将二十四种不同的不朽 细胞系分成四个互补群进行无限分裂。 这表明，至少有四条道路可以永生， 至少有四个基因或基因组参与正常细胞生长 控制 利用微细胞介导的染色体转移技术， 我们已经确定，正常人类4号染色体的引入 分成三个永生的人类细胞系， B，导致增殖丧失。 这是一个具体的影响， 组B细胞系，因为永生细胞的分裂能力 分配给其它组的品系不受该染色体的影响， 正常的11号染色体对任何永生细胞都没有影响， 测试线路 这些结果表明，存在细胞衰老 人类4号染色体上的相关基因。我们还发现， 1号染色体诱导一个永生人类细胞增殖丧失 分配给C组的行，在本提案中，我们计划采取 多管齐下的方法克隆4号染色体上的基因， 在衰老和永生化过程中调节其表达。 我们 也将决定1号染色体是否影响 其他分配到C组的永生人类细胞系的潜力。如果 如果是这样，这将表明另一个细胞衰老基因是 我们将尝试将该区域定位在 第一条染色体。

Normal human cells in vitro exhibit a stringent limitation of division capacity. In contrast, tumor-derived and virus-, carcinogen- or irradiation-transformed cells can divide indefinitely (immortal). We do not yet understand the mechanisms that limit the division potential of normal human cells or the changes occurring to yield immortal cells. However, from cell hybrid studies we have found that the immortal phenotype results from recessive changes in normal cell growth control. We have exploited this fact to separate twenty four different immortal cell lines into four complementation groups for indefinite division. This indicates that there are at least four paths to immortality and that at least four genes or sets of genes are involved in normal cell growth control. Using the technique of microcell mediated chromosome transfer, we have determined that the introduction of a normal human chromosome 4 into three immortal human cell lines that assign to complementation group B, results in loss of proliferation. This is a specific effect to the group B cell lines, because the division capability of immortal cell lines assigned to the other groups is not affected by this chromosome, and a normal chromosome 11 has no effect on any of the immortal cell lines tested. These results indicate that there is a cell senescence related gene(s) on human chromosome 4. We have also found that a normal chromosome 1 induces loss of proliferation in one immortal human cell line that assigns to group C., In this proposal, we plan to take multipronged approaches to clone the gene on chromosome 4 and study regulation of its expression during senescence and immortalization. We will also determine whether chromosome 1 affects the proliferation potential of other immortal human cell lines that assign to group C. If it does, this would indicate that another cellular senescence gene(s) is present on this chromosome and we will attempt to localize the region on chromosome 1 that is involved.