TRANSLATIONAL CONTROL IN C. ELEGANS EMBRYOS

许多mRNAs的3‘非翻译区(UTR)含有控制其翻译的调控序列。在早期胚胎中，这是一种特别重要的基因调控手段，在分化细胞中控制生长、分化和新陈代谢也很重要。尽管这种形式的基因调控很重要，但mRNA3‘端序列调控翻译的机制(S)尚不清楚。线虫胚胎中PAL-1蛋白的合成受其mRNA的PAL-1 3‘非编码区和RNA结合蛋白MEX-3序列的调控。MEX-3抑制PAL-1在卵母细胞和早期卵裂球中的翻译。在4-细胞期，这种抑制在后卵裂球中被抑制，PAL-1在这些细胞中被翻译。本研究的目的是研究MEX-3是如何抑制PAL-1翻译的，以及这种抑制是如何被调节以控制PAL-1翻译的模式的。具体目标包括，识别调节PAL-1翻译所需的特定RNA序列和蛋白质，然后从遗传学和生物化学的角度表征它们的调节和功能。包括MEX-3在内的10种蛋白质已被确定为调节PAL-1翻译模式所需的蛋白质。经酵母双杂交鉴定，其中6个为MEX-3相互作用蛋白。通过RNA干扰分析确定了它们的功能。在已知的模式突变体中发现了另外三个PAL-1翻译调控因子。这项研究的长期目标是阐明3‘非编码区介导的翻译控制的分子机制(S)，并深入了解翻译控制如何在早期胚胎中建立模式。

The 3' untranslated region (UTR) of many mRNAs contains regulatory sequences that control their translation. This is a particularly prominent means of gene regulation in early embryos and is also important in differentiated cells to control growth, differentiation, and metabolism. Despite the importance of this form of gene regulation, the mechanism(s) by which sequences at the 3' end of mRNA regulate translation are unclear. Synthesis of the PAL-1 protein in the C. elegans embryo is regulated by sequences in the pal-1 3' UTR of the mRNA and the RNA-binding protein MEX-3. MEX-3 represses pal-1 translation in oocytes and early blastomeres. At the 4-cell stage, this repression is inhibited in the posterior blastomeres and pal-1 is translated in these cells. The goal of the proposed research is to investigate how MEX-3 represses pal-1 translation, and how this repression is regulated to control the pattern of pal-1 translation. The specific aims include, identifying the specific RNA sequences and proteins required to regulate pal-1 translation and then genetically and biochemically characterizing their regulation and function. Ten proteins, including MEX-3, have been identified that are required to regulate the pattern of pal- 1 translation. Six of these proteins were identified as MEX-3 interacting proteins using the yeast 2-hybrid assay. Their functions were assigned by RNA interference analysis. Three additional regulators of pal-1 translation were identified among known patterning mutants. The long-term goals of the proposed research is to elucidate the molecular mechanism(s) of 3' UTR mediated translational control and to provide insight into how patterns in early embryos are set-up by translational control.