Progressive states of cell-cycle withdrawal

项目摘要 衰老是细胞由于细胞老化而永久停止增殖的过程 或破坏，但不会死亡。在癌症治疗过程中，通常需要诱导衰老 以防止异常细胞的增殖，但它也阻碍细胞功能， 再生能力随着年龄的增长。细胞衰老的研究受到以下事实的阻碍， 衰老很难与细胞周期退出的其他状态区分开来， 静止，短暂的细胞静止状态。这是因为静止和衰老是 由重叠的分子标记物定义，并且因为这些细胞周期转换发生在 从细胞到细胞的不均匀性。尽管有明显的医学相关性，但尚不清楚是否 衰老和静止是真正不同的状态。在这里，我们提出测试的假设 衰老和静止存在于细胞周期退出的连续体中， 随着细胞衰老，细胞周期再进入的可能性稳定地向零下降。 我们将利用我们在长期，延时显微镜，自动单， 细胞跟踪，以及细胞周期进程和细胞周期传感器的开发 提取，以揭示细胞周期提取的等级，这是不可见的标准批量 接近。我们的具体目标是：1）确定流行的预测能力 作为衰老的二元标记物和作为静止的分级标记物的衰老标记物 2）为了在转录组水平上确定静止和衰老是否是 不同的状态或细胞周期退出连续体的一部分，以及3）为了识别DNA 损伤和端粒特征，预测随着细胞年龄的增长， 复制性衰老 如果成功，这项工作将提高我们从分子水平上定义衰老状态的能力， 将产生关于衰老开始的新的基础知识。我们的工作可以 提高预测癌症治疗后肿瘤复发的能力，帮助量化细胞的 生理年龄和生殖潜力，确定恢复衰老细胞活力的方法， 提高消除衰老细胞的抗衰老药物的安全性。

Project Summary Senescence is the process by which a cell permanently stops proliferating due to cellular aging or damage but does not die. Induction of senescence is often desirable during cancer treatment to prevent the proliferation of aberrant cells, but it also impedes cellular function and regenerative capacity as we age. The study of cellular senescence is hindered by the fact that senescence is difficult to distinguish from other states of cell-cycle withdrawal such as quiescence, a transient cellular resting state. This is because quiescence and senescence are defined by overlapping molecular markers and because these cell-cycle transitions occur heterogeneously from cell to cell. Despite obvious medical relevance, it is unclear whether senescence and quiescence are truly distinct states. Here we propose to test the hypothesis that senescence and quiescence exist on a continuum of cell-cycle withdrawal where the probability of cell-cycle re-entry steadily declines toward zero as cells become senescent. We will leverage our unique expertise in long-term, time-lapse microscopy, automated single- cell tracking, and the development of sensors for cell-cycle progression and cell-cycle withdrawal to unveil gradations of cell-cycle withdrawal that are invisible by standard bulk approaches. Our specific aims are 1) To determine the predictive power of prevailing senescence markers as binary markers of senescence and as graded markers of quiescence depth, 2) To determine at the transcriptomic level whether quiescence and senescence are distinct states or part of a continuum of cell-cycle withdrawal, and 3) To the identify the DNA damage and telomere features that predict permanent cell-cycle withdrawal as cells age toward replicative senescence. If successful, this work will improve our ability to define molecularly the state of senescence and will generate new fundamental knowledge about the onset of senescence. Our work could improve the ability to predict tumor relapse after cancer therapy, help quantify a cell’s physiological age and reproductive potential, identify ways to rejuvenate aged cells, and improve the safety of senolytic drugs that eliminate senescent cells.