Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
Mol Cell. 2020 May 21;78(4):700-713.e7. doi: 10.1016/j.molcel.2020.03.021. Epub 2020 Apr 13.
Impairment of ribosome function activates the MAPKKK ZAK, leading to activation of mitogen-activated protein (MAP) kinases p38 and JNK and inflammatory signaling. The mechanistic basis for activation of this ribotoxic stress response (RSR) remains completely obscure. We show that the long isoform of ZAK (ZAKα) directly associates with ribosomes by inserting its flexible C terminus into the ribosomal intersubunit space. Here, ZAKα binds helix 14 of 18S ribosomal RNA (rRNA). An adjacent domain in ZAKα also probes the ribosome, and together, these sensor domains are critically required for RSR activation after inhibition of both the E-site, the peptidyl transferase center (PTC), and ribotoxin action. Finally, we show that ablation of the RSR response leads to organismal phenotypes and decreased lifespan in the nematode Caenorhabditis elegans (C. elegans). Our findings yield mechanistic insight into how cells detect ribotoxic stress and provide experimental in vivo evidence for its physiological importance.
核糖体功能障碍激活 MAPKKK ZAK，导致丝裂原激活蛋白激酶（MAP）激酶 p38 和 JNK 的激活和炎症信号转导。这种核糖体毒性应激反应（RSR）的激活机制仍完全不清楚。我们发现 ZAK 的长异构体（ZAKα）通过将其柔性 C 末端插入核糖体亚基间空间，直接与核糖体结合。在这里，ZAKα 结合 18S 核糖体 RNA（rRNA）的螺旋 14。ZAKα 中的相邻结构域也探测核糖体，并且这些传感器结构域对于在抑制 E 位、肽基转移酶中心（PTC）和核糖体毒素作用后，RSR 的激活是至关重要的。最后，我们发现 RSR 反应的缺失会导致线虫秀丽隐杆线虫（C. elegans）的生物体表型和寿命缩短。我们的研究结果提供了对细胞如何检测核糖体毒性应激的机制见解，并为其生理重要性提供了实验体内证据。
