Circadian clock regulation of mRNA translation through eukaryotic elongation factor eEF-2
Circadian clock regulation of mRNA translation through eukaryotic elongation factor eEF-2
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DOI：
10.1073/pnas.1525268113
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发表时间：
2016-08-23
影响因子：
11.1
通讯作者：
Bell-Pedersen, Deborah
中科院分区：
文献类型：
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作者：
Caster, Stephen Z.;Castillo, Kathrina;Bell-Pedersen, Deborah
生物钟对基因调控有着深远的影响，它控制着真核生物中多达一半的表达基因有节奏的转录积累。也有证据表明mRNA翻译的时钟控制，但这种调节的程度和机制尚不清楚。在粗糙脉孢菌中，当细胞在恒定条件下生长时，生物钟在保守的丝裂原活化蛋白激酶（MAPK）途径的激活中产生每日节律，包括充分表征的p38 β传感（OS）MAPK途径的节律性激活。MAPK OS-2（P-OS-2）的节律性磷酸化导致OS-2下游靶标的时间控制。结果表明，渗透胁迫对N. crassa诱导真核延伸因子-2（eEF-2）激酶、辐射敏感性补充激酶-2（RCK-2）的磷酸化，并且RCK-2是eEF-2（翻译延伸的关键调节因子）的高水平磷酸化所必需的。野生型细胞中磷酸化RCK-2和磷酸化eEF-2循环水平丰富，但在缺失OS-2或核心时钟成分频率（FRQ）的细胞中则不然。在恒定条件下生长的细胞的翻译提取物显示在主观早晨晚些时候翻译活性降低，与eEF-2磷酸化的峰值一致，并且体内组成型mRNA水平的谷胱甘肽S-转移酶（GST-3）的节律性翻译依赖于eEF-2活性的昼夜调节。相反，磷酸化eEF-2水平的节律对于时钟蛋白FRQ积累的节律不是必需的，表明eEF-2活性的时钟控制促进特定mRNA的节律性翻译。
The circadian clock has a profound effect on gene regulation, controlling rhythmic transcript accumulation for up to half of expressed genes in eukaryotes. Evidence also exists for clock control of mRNA translation, but the extent and mechanisms for this regulation are not known. In Neurospora crassa, the circadian clock generates daily rhythms in the activation of conserved mitogen-activated protein kinase (MAPK) pathways when cells are grown in constant conditions, including rhythmic activation of the well-characterized p38 osmosensing (OS) MAPK pathway. Rhythmic phosphorylation of the MAPK OS-2 (P-OS-2) leads to temporal control of downstream targets of OS-2. We show that osmotic stress in N. crassa induced the phosphorylation of a eukaryotic elongation factor-2 (eEF-2) kinase, radiation sensitivity complementing kinase-2 (RCK-2), and that RCK-2 is necessary for high-level phosphorylation of eEF-2, a key regulator of translation elongation. The levels of phosphorylated RCK-2 and phosphorylated eEF-2 cycle in abundance in wild-type cells but not in cells deleted for OS-2 or the core clock component FREQUENCY (FRQ). Translation extracts from cells grown in constant conditions show decreased translational activity in the late subjective morning, coincident with the peak in eEF-2 phosphorylation, and rhythmic translation of glutathione S-transferase (GST-3) from constitutive mRNA levels in vivo is dependent on circadian regulation of eEF-2 activity. In contrast, rhythms in phosphorylated eEF-2 levels are not necessary for rhythms in accumulation of the clock protein FRQ, indicating that clock control of eEF-2 activity promotes rhythmic translation of specific mRNAs.