Laboratory of Microbial Technology, Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Kyoto 606-8585, Japan.
Biochem J. 2012 Sep 1;446(2):225-33. doi: 10.1042/BJ20120583.
The stress response of eukaryotic cells often causes an attenuation of bulk translation activity and the accumulation of non-translating mRNAs into cytoplasmic mRNP (messenger ribonucleoprotein) granules termed cytoplasmic P-bodies (processing bodies) and SGs (stress granules). We examined effects of acidic stress on the formation of mRNP granules compared with other forms of stress such as glucose deprivation and a high Ca²⁺ level in Saccharomyces cerevisiae. Treatment with lactic acid clearly caused the formation of P-bodies, but not SGs, and also caused an attenuation of translation initiation, albeit to a lesser extent than glucose depletion. P-body formation was also induced by hydrochloric acid and sulfuric acid. However, lactic acid in SD (synthetic dextrose) medium with a pH greater than 3.0, propionic acid and acetic acid did not induce P-body formation. The results of the present study suggest that the assembly of yeast P-bodies can be induced by external conditions with a low pH and the threshold was around pH 2.5. The P-body formation upon acidic stress required Scd6 (suppressor of clathrin deficiency 6), a component of P-bodies, indicating that P-bodies induced by acidic stress have rules of assembly different from those induced by glucose deprivation or high Ca²⁺ levels.
真核细胞的应激反应通常会导致翻译活性的减弱，并将非翻译的 mRNAs 积累到细胞质 mRNP（信使核糖核蛋白）颗粒中，这些颗粒被称为细胞质 P 体（处理体）和 SGs（应激颗粒）。我们研究了酸性应激对 mRNP 颗粒形成的影响，与葡萄糖剥夺和酵母中高 Ca²⁺水平等其他形式的应激进行了比较。乳酸处理明显导致 P 体的形成，但不导致 SG 的形成，并且也导致翻译起始的减弱，尽管程度比葡萄糖耗尽要小。盐酸和硫酸也诱导 P 体的形成。然而，在 pH 值大于 3.0 的 SD（合成葡萄糖）培养基中的乳酸、丙酸和乙酸不会诱导 P 体的形成。本研究的结果表明，酵母 P 体的组装可以被 pH 值较低的外部条件诱导，阈值约为 pH 2.5。酸性应激引起的 P 体形成需要 Scd6（网格蛋白缺陷 6 的抑制剂），这是 P 体的一个组成部分，表明酸性应激诱导的 P 体组装规则与葡萄糖剥夺或高 Ca²⁺水平诱导的规则不同。
