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首页> 外文期刊>Molecular and Cellular Biology >Translational control of ribosomal protein synthesis during early Dictyostelium discoideum development.
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Translational control of ribosomal protein synthesis during early Dictyostelium discoideum development.

机译：盘基网柄菌早期发育过程中核糖体蛋白合成的翻译控制。

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Throughout the developmental program of Dictyostelium discoideum there are substantial changes in the rates of both ribosome utilization and rRNA transcription and processing. We examined the regulation of ribosomal protein (r-protein) gene expression and found that, at the start of development, expression of these genes was drastically and specifically reduced by a block to translational initiation. An apparently separate event signals a sudden decrease in the relative amount of r-protein mRNA at about 10 h of development, a time when aggregated amoebae are forming tight cell-cell contacts. For the first 9 h of development, the relative amount of r-protein mRNA remained essentially unchanged and comparable to levels detected in growing cells. While the r-protein mRNAs were almost fully loaded on polysomes during vegetative growth, they were specifically excluded from polysomes at the start of development. The translational block was not the result of irreversible structural changes which inactivate the r-protein mRNAs since they remained translatable both in vitro, in wheat germ extracts, and in vivo, where they were recruited onto polysomes in the presence of the elongation inhibitor cycloheximide. In addition, precise measurements of poly(A) tail lengths on individual hybrid-selected mRNA species showed that there is no difference in the poly(A) tail length of r-protein mRNA isolated from growing cells and 1-h developing cells. Therefore, changes in translational efficiency cannot be attributed to cleavage of poly(A) tails.
机译：在整个盘基网柄菌的发育计划中，核糖体利用率，rRNA转录和加工率均发生重大变化。我们检查了核糖体蛋白（r蛋白）基因表达的调控，发现在开发开始时，这些基因的表达就急剧地减少了，特别是通过阻止翻译起始而减少了。明显分开的事件表明，在发育的大约10小时（聚集的变形虫形成紧密的细胞-细胞接触）时，r蛋白mRNA的相对含量突然下降。在发育的前9小时，r蛋白mRNA的相对数量基本保持不变，与在生长细胞中检测到的水平相当。尽管r-蛋白质mRNA在营养生长过程中几乎完全负载在多核糖体上，但在发育开始时却特别将其排除在多核糖体之外。翻译阻滞不是使r蛋白mRNA失活的不可逆结构变化的结果，因为它们在体外，小麦胚芽提取物中和体内都保持可翻译的状态，在存在延长抑制剂环己酰亚胺的情况下，它们被募集到多核糖体上。此外，精确测量单个杂交选择的mRNA种类的poly（A）尾长显示，从生长细胞和1-h发育细胞分离的r蛋白mRNA的poly（A）尾长没有差异。因此，翻译效率的变化不能归因于poly（A）尾巴的分裂。

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