Temporal Control of Development in C.elegans

描述（由申请人提供）：这项工作的目的是了解 在后生动物发育过程中控制特定细胞命运决定的时间机制 发展线虫C.优雅是全球性的 控制不同事件的顺序和时间的时间调节器 这项研究将探讨如何一个胚胎发育 这些事件，侧皮下“缝”细胞的终末分化， 在野生型动物中暂时限于最后的蜕皮。突变 异时基因导致缝细胞终末分化发生 早于或晚于正常。近12个异时基因已经被 它们可以被分为两类，根据它们的 已知或提议的行动时间。早期作用基因指定发育 经过前三个幼虫阶段（L1-L3），然后是晚期阶段， 作用基因接管并指导发育的剩余部分（晚期L3-成体）。 本研究将探讨四个异时基因的分子作用， 早期作用基因lin-42和lin-58以及晚期作用基因lin-57和lin-58， 林-29。本提案中描述的实验将试图了解 这些基因的功能在其他基因的背景下，构成了 异时基因通路遗传和分子上位性实验将在 这些基因的表达模式将被确定。林-42 编码一种与果蝇时期相似的蛋白质，这种蛋白质参与了 第二类生物计时机制，昼夜节律的控制。 拟议的实验将调查这一序列的功能相关性 同源性和酵母双杂交系统将被用来发现 UN-42相互作用蛋白lin-58将被克隆， 将用于设计其功能的分子测试。 因为lin-57只有一个亚纯型等位基因， 以鉴定lin-57（无效）突变。这些等位基因将是 特征和假设lin.57在时间上由21 将测试nt let-7调节RNA。林-29扮演了一个关键角色， 缝细胞终末分化的下游调节因子。分子 确定lin-29活性时间和序列的关键机制 对于lin-29的调节将被定义。最后，基因筛查将 用于寻找其他异时基因。 lin-29功能的丧失导致成体阶段的细胞无限期地 重复细胞分裂的幼虫程序，而不是离开细胞 循环和分化。因此，lin-29可以概括地认为是 抑癌基因：其功能是细胞周期退出所必需的基因 lin-29的时间控制提供了一个模型， 在发育的特定时间停止分裂， 区分。这些知识有助于我们理解这些问题 当增长控制出现问题时，例如不适当的恢复 在某些癌症中发生的细胞分裂。

DESCRIPTION (provided by applicant): The aim of this work is to understand the timing mechanisms that govern specific cell fate decisions during metazoan development. The heterochronic genes of the nematode C. elegans are global temporal regulators that control the sequence and timing of diverse events during post embryonic development This research will investigate how one of these events, the terminal differentiation of lateral hypodermal "seam" cells, becomes temporally restricted to the final molt in wild-type animals. Mutations in the heterochronic genes cause seam cell terminal differentiation to occur earlier or later than normal. Nearly a dozen heterochronic genes have been identified and they can be roughly divided into two classes based upon their known or proposed times of action. The early acting genes specify developmental progression through the first three larval stages (L1-L3) and then the late acting genes take over and direct the remainder of development (late L3-Adult). This research will investigate the molecular roles of four heterochronic genes, the early acting genes, lin-42 and lin-58 and the late acting genes, lin-57 and lin-29. The experiments described in this proposal will seek to understand the functions of these genes in the context of the other genes that comprise the heterochronic gene pathway. Genetic and molecular epistasis experiments will be performed and the expression patterns of these genes will be determined. lin-42 encodes a protein with similarity to Drosophila Period, a protein involved in a second type of biological timing mechanism, control of circadian rhythms. Proposed experiments will investigate the functional relevance of this sequence homology and the yeast two-hybrid system will be employed to discover UN-42-interacting proteins. lin-58 will be cloned, and the information gleaned from its identity will be used to design molecular tests of its function. Because only a single, hypomorphic allele of lin-57 exists, genetic screens will be performed to identify lin-57(null) mutations. These alleles will be characterized and the hypothesis that lin.57 is temporally controlled by the 21 nt let-7 regulatory RNA will be tested. lin-29 plays a key role as the most downstream regulator of seam cell terminal differentiation. The molecular mechanism that times lin-29 activity will be determined and sequences critical for lin-29 regulation will be defined. Finally, genetic screens will be employed to search for addition heterochronic genes. Loss of lin-29 function causes cells of the adult stage to indefinitely reiterate the larval program of cell divisions rather than exiting the cell cycle and differentiating. Thus, lin-29 can be thought of in general terms as an anti-oncogene: a gene whose function is required for cell cycle exit Temporal control of lin-29 provides a model for how cells within an organism are instructed to cease dividing at a specific time in development and differentiate. This knowledge should aid in our understanding of the problems that occur when growth controls go awry, such as the inappropriate resumption of cell divisions that occurs in some cancers.