NEURONAL TURNOVER IN ADULT BRAIN USING AMS FOR RETROSPECTIVE BIRTH DATING CELLS

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 已知神经发生发生在成年动物大脑的特定区域，但成年人类大脑中神经发生的程度和可比性更难确定，迄今为止在很大程度上未知。 用于测定细胞年龄的传统方法在它们提供的信息方面是有限的，或者不适合人类使用。 因此，目前还没有方法来研究细胞周转在人。我们建议开发一种方法，追溯出生日期的细胞。 我们感兴趣的是使用炸弹脉冲碳-14（C14）测年作为一种方法来测量成年人大脑中特定细胞群的近似年龄。 该方法基于确定同位素C14在基因组DNA中的比例。 C14测量将使用高灵敏度加速器质谱仪（AMS）进行。 细胞在终末分化后，不再分裂。 由于最后一次细胞分裂代表细胞合成DNA的最后一个时间点，其染色体DNA将反映细胞出生时的年龄。 传统上，C14相对于其他碳物种的缓慢衰变使其具有多年的时间分辨率，但由于20世纪50年代末和60年代初的核试验，大气中的C14水平急剧增加。 此后，这一水平以指数方式下降，使人们能够解决C14在年份范围内的差异。 由于DNA具有C14含量，反映了它合成的时间，因此确定染色体DNA的C14含量将使我们能够回顾细胞的出生日期，从而建立细胞更新。 了解基本的生物学过程的关键是关于细胞周转的信息。 除了对正常细胞更新感兴趣之外，许多疾病被认为会影响新细胞的生成。 有关疾病状态下细胞周转的信息可能为疾病的病理过程提供新的见解，并可能提出新的治疗策略。 使用AMS从马脑DNA中测定C14的初步实验取得了令人鼓舞的结果。 下一步是研究AMS从马血、大脑和牙齿中提取的DNA中确定C14的准确日期。 然后使用FACS分析分离特定的细胞群（其允许分离特定的细胞群，例如可以使用神经元特异性标记物如NeuN、微管蛋白或Thy 1分选神经元）。 一旦这项技术建立起来，我们的目标是转移到人体材料上，并研究特定人类病理学中的细胞周转。 道德允许获取死后人体组织。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Neurogenesis is known to occur in specific regions of the adult animal brain, but the extent and comparability of neurogenesis in the adult human brain is much harder to determine, and to date largely unknown. Traditional methods used for dating cells are limited in the information they provide, or are not appropriate for human use. Thus, currently there is no method available to study cellular turnover in man. We propose to develop a method for the retrospective birth dating of cells. We are interested in using bomb pulse carbon-14 (C14) dating as a method for measuring the approximate age of specific populations of cells in the adult human brain. This method is based on establishing the proportion of the isotope C14 in genomic DNA. C14 measurements will be made using the highly sensitive accelerator mass spectrometer (AMS). After a cell has terminally differentiated it does not divide again. Since the last cell division represents the last time point when the cell synthesized DNA, its chromosomal DNA will reflect the age when the cell was born. Traditionally, the slow decay of C14 relative to other carbon species has given it a temporal resolution of many years, however due to nuclear tests in the late 1950s and early 1960s, the level of C14 in the atmosphere has increased dramatically. This level has since dropped off in an exponential fashion, allowing one to resolve C14 differences in the range of years. Because DNA has a C14 content reflective of the time when it was synthesized, establishing the C14 content of chromosomal DNA will enable us to retrospectively birth date cells, and thus establish cellular turnover. Crucial to the understanding of basic biological processes, is information about cellular turnover. As well as having an interest in normal cellular turnover, many diseases are thought to be affected in their generation of new cells. Information about cellular turnover in disease states may provide novel insights into the pathological processes of the disease, and possibly suggest new therapeutic strategies. Preliminary experiments using AMS to date C14 from horse brain DNA have yielded encouraging results. The next step is to look at how accurately AMS dates C14 from DNA extracted from horse blood, brain and teeth. Particular populations of cells will then be isolated using FACS analysis (which allows specific cell populations to be isolated e.g. one can sort for neurons using neuronal specific markers such as NeuN, ¿ tubulin or Thy1). Once this technique has been established we aim to move onto human material, and study cellular turnover in specific human pathologies. Ethical permission to obtain postmortem human material has been granted.