Interfaculty Institute of Biochemistry, Eberhard-Karls-Universität Tübingen, Tübingen, 72076, Germany.
Traffic. 2012 Dec;13(12):1642-52. doi: 10.1111/tra.12011. Epub 2012 Oct 11.
Localization of messenger RNA (mRNAs) contributes to generation and maintenance of cellular asymmetry, embryonic development and neuronal function. The She1-3 protein machinery in Saccharomyces cerevisiae localizes >30 mRNAs to the bud tip, including 13 mRNAs encoding membrane or secreted proteins. Ribonucleoprotein (RNP) particles can co-localize with tubular endoplasmic reticulum (ER) structures that form the initial elements for segregation of cortical ER (cER), suggesting a coordination of mRNA localization and cER distribution. By investigating localization of MS2-tagged mRNAs in yeast defective at various stages of cER segregation, we demonstrate that proper cER segregation is required for localization of only a subset of mRNAs. These mRNAs include WSC2, IST2, EAR1 and SRL1 that encode membrane or ER associated proteins and are expressed during S and G2 phases of the cell cycle when tubular ER movement into the bud occurs. Translation of WSC2 is not required for localization, ruling out co-translational targeting of this mRNA. Localization of ASH1 mRNA is independent of cER segregation, which is consistent with the expression pattern of ASH1 at late mitosis. Our findings indicate the presence of two different pathways to localize mRNAs to the yeast bud.
信使 RNA (mRNAs) 的定位有助于细胞不对称性的产生和维持、胚胎发育和神经元功能。酿酒酵母中的 She1-3 蛋白机制将超过 30 种 mRNA 定位到芽尖，包括编码膜或分泌蛋白的 13 种 mRNA。核糖核蛋白 (RNP) 颗粒可以与管状内质网 (ER) 结构共定位，这些结构构成了皮质 ER (cER) 分离的初始元件，这表明 mRNA 定位和 cER 分布的协调。通过研究在 cER 分离的各个阶段有缺陷的酵母中 MS2 标记的 mRNAs 的定位，我们证明了只有一部分 mRNAs 的正确 cER 分离是必需的。这些 mRNAs 包括 WSC2、IST2、EAR1 和 SRL1，它们编码膜或 ER 相关蛋白，并且在细胞周期的 S 和 G2 期表达，此时管状 ER 进入芽中。WSC2 的翻译对于定位不是必需的，这排除了这种 mRNA 的共翻译靶向。ASH1 mRNA 的定位不依赖于 cER 分离，这与 ASH1 在有丝分裂后期的表达模式一致。我们的发现表明存在两种不同的途径将 mRNAs 定位到酵母芽中。
