PTEN/DAF-18 and FOXO/DAF-16 function in blast cell quiescence in C. elegans dauer developmental arrest

 描述(申请人提供)：细胞静止是一种细胞周期退出的可逆状态，其机制在很长一段时间内还没有完全阐明。 但它们与人类疾病高度相关，特别是癌症，这涉及严重的细胞周期失调，但也可能需要静止的过程，如转移。两个已知的在哺乳动物系统中对静止很重要的基因包括PTEN(磷酸酶和紧张素同源物)和转录因子FOXO(叉头盒O类)。这两个基因在线虫中都是保守的，这为线虫提供了一个易于处理的模型系统和一个强大的遗传工具箱。线虫是研究静止的一个特别好的模型，因为在恶劣的环境条件下，它可以进入被称为达尔停滞的阶段，在这个阶段，胚胎后发育中断数月，发育中的组织中的细胞必须保持静止，直到条件改善。达尔滞育使其发育受阻的器官之一是性腺，它由体细胞性腺和生殖线组成。线虫的PTEN，DAF-18和FOXO，DAF-16的同源物都需要在体细胞性腺和生殖系中保持静止。为了阐明Dauer性腺中DAF-18/PTEN和DAF-16/FOXO的功能是如何响应环境变化的，本研究将以DAF-18/PTEN和DAF-16/FOXO为研究模型。已知DAF-18是达尔族生殖系静止所必需的，而未发表的研究表明，DAF-18和DAF-16都是躯体性腺静止所必需的。这项建议将通过以下目的进一步确定DAF-18在维持达尔尔体细胞性腺和生殖系静止中的作用：第一，通过使用增殖标记，更好地描述daf-18在调节达尔体性腺和生殖系静止中的功能，并确定其在这一功能中的组织特异性；第二，利用遗传分析来确定DAF-18调节的信号通路，以维持Dauer性腺的静止，并测试规范的细胞周期调节因子daf-18和daf-16是否调节作为维持静止的机制；第三，使用增殖标志物筛选DAF-18调节体细胞性腺静止的新调节因子。了解DAF-18/PTEN和DAF-16/FOXO是如何调控线虫静止的，并在线虫中识别新的调节因子--一种足够复杂的遗传模型，足以概括涉及的众多信号通路--将有助于阐明在复杂的哺乳动物环境中实现静止的机制。了解这一机制将与人类疾病和涉及静止的治疗相关，包括癌症，以及它可以利用休眠来逃避治疗和转移的方法。

 DESCRIPTION (provided by applicant): The mechanisms by which cellular quiescence, a reversible state of cell cycle exit, is achieved over long periods of time are not fully elucidated but are highly relevant to human disease, particularly cancer, which involves heavy dysregulation of the cell cycle but also may require quiescence for processes such as metastasis. Two genes known to be important for quiescence in mammalian systems include PTEN (phosphatase and tensin homolog) and the transcription factor FOXO (Forkhead box class O). Both of these genes are conserved in the nematode Caenorhabditis elegans, which provides a tractable model system with a powerful genetic toolbox. C. elegans is in particular an excellent model for studying quiescence since, in adverse environmental conditions, it can enter a stage called dauer arrest in which postembryonic development is interrupted for months and cells in developing tissues must maintain quiescence until conditions improve. One of the organs whose development is halted by dauer diapause is the gonad, which consists of both the somatic gonad and the germline. Both the C. elegans homolog of PTEN, DAF-18, and of FOXO, DAF-16, are required to maintain quiescence in the somatic gonad and germline. In order to elucidate how quiescence is maintained in response to environmental context, this proposal will focus on DAF-18/PTEN and DAF-16/FOXO function in the dauer gonad as a model of quiescence. DAF-18 is known to be required for germline quiescence in dauer, and unpublished studies show both DAF-18 and DAF-16 are required for quiescence in the somatic gonad. This proposal will further characterize the role of DAF-18 in maintaining quiescence in the somatic gonad and the germline in dauer through the following aims: first, to better characterize daf-18 function in regulating somatic gonad and germline quiescence in dauer through use of proliferation markers and to determine its tissue specificity in this function; second, to use genetic analysis to identify the signaling pathways regulated by daf-18 to maintain quiescence in the dauer gonad and to test for daf-18 and daf-16 regulation of a canonical cell cycle regulator as a mechanism of maintaining quiescence; third, to conduct a screen for novel regulators of somatic gonad quiescence in dauer using markers of proliferation. Understanding how DAF-18/PTEN and DAF-16/FOXO regulate quiescence and identifying novel regulators in C. elegans - a genetic model complex enough to recapitulate the numerous signaling pathways involved - will help clarify the mechanism by which quiescence is achieved in complex mammalian contexts. Understanding this mechanism will have relevance for human disease and therapy involving quiescence, including cancer and the means by which it can utilize dormancy to evade therapies and metastasize.