Kugou Kazuto, Sasanuma Hiroyuki, Matsumoto Kouji, Shirahige Katsuhiko, Ohta Kunihiro
Genetic System Regulation Laboratory, RIKEN, Discovery Research Institute, Wako, Saitama, Japan.
Genes Genet Syst. 2007 Feb;82(1):21-33. doi: 10.1266/ggs.82.21.
Mre11, together with Rad50 and Xrs2/NBS, plays pivotal roles in homologous recombination, repair of DNA double strand breaks (DSBs), activation of damage-induced checkpoint, and telomere maintenance. Here we demonstrate that the absence of Mre11 in yeast causes specific effects on regulation of a class of meiotic genes for spore development. Using DNA microarray assays to analyze yeast mutants defective for meiotic DSB formation, we revealed that the meiotic expression profile in the mre11Delta cells was generally unaffected when compared to the one in the wild-type strain, although the activation of about 90 meiotic genes were severely and specifically impaired in early meiosis. These defects were confirmed by northern and lacZ reporter gene assays. Interestingly, a substantial portion of the severely affected genes includes genes responsible for spore wall biogenesis, the defects of which may account for the fragile spore wall phenotype of the mre11Delta strain. The transcriptional deficiency was not observed in other DSB mutants such as rad50Delta, xrs2Delta, spo11Delta, and spo11Y135F, suggesting the transcriptional defect in mre11Delta is due to neither lack of meiotic DSB formation, nor disintegrity of Mre11-Rad50-Xrs2 complex. In addition, the deficiency of mre11Delta in gene activation was not alleviated by the deletion of RAD24. Therefore, it is unlikely that DNA damage checkpoint activation by mre11Delta caused transcriptional deficiency. We also found that a C-terminus DNA binding domain truncation mutant (mre11DeltaC49), which has meiosis-specific defects, exhibited transcriptional defects as observed in mre11Delta, whereas an N-terminal phosphoesterase mutant (mre11D16A) does not. Taken together, we propose that Mre11 is involved in the regulation of a specific class of genes during spore development through its C-terminus domain.
Mre11与Rad50和Xrs2/NBS一起，在同源重组、DNA双链断裂（DSB）修复、损伤诱导的检查点激活以及端粒维持中发挥关键作用。在此，我们证明酵母中Mre11的缺失对一类参与孢子发育的减数分裂基因的调控产生特定影响。通过DNA微阵列分析来检测减数分裂DSB形成缺陷的酵母突变体，我们发现与野生型菌株相比，mre11Δ细胞中的减数分裂表达谱总体上未受影响，尽管约90个减数分裂基因的激活在减数分裂早期受到严重且特异性的损害。这些缺陷通过Northern印迹和lacZ报告基因检测得以证实。有趣的是，受严重影响的基因中有很大一部分包括负责孢子壁生物合成的基因，其缺陷可能解释了mre11Δ菌株孢子壁易碎的表型。在其他DSB突变体如rad50Δ、xrs2Δ、spo11Δ和spo11Y135F中未观察到转录缺陷，这表明mre11Δ中的转录缺陷既不是由于减数分裂DSB形成的缺乏，也不是由于Mre11-Rad50-Xrs2复合物的不完整。此外，RAD24的缺失并未缓解mre11Δ在基因激活方面的缺陷。因此，mre11Δ激活DNA损伤检查点不太可能导致转录缺陷。我们还发现，具有减数分裂特异性缺陷的C末端DNA结合结构域截短突变体（mre11ΔC49）表现出与mre11Δ中观察到的转录缺陷，而N末端磷酸酯酶突变体（mre11D16A）则没有。综上所述，我们提出Mre11通过其C末端结构域参与孢子发育过程中特定一类基因的调控。
