Department of Psychology, University of Toronto, Toronto, Ontario, Canada.
Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America.
PLoS Comput Biol. 2021 May 28;17(5):e1008987. doi: 10.1371/journal.pcbi.1008987. eCollection 2021 May.
Modification of the Per2 clock gene in mPer2Luc reporter mice significantly alters circadian function. Behavioral period in constant dark is lengthened, and dissociates into two distinct components in constant light. Rhythms exhibit increased bimodality, enhanced phase resetting to light pulses, and altered entrainment to scheduled feeding. Mechanistic mathematical modelling predicts that enhanced protein interactions with the modified mPER2 C-terminus, combined with differential clock regulation among SCN subregions, can account for effects on circadian behavior via increased Per2 transcript and protein stability. PER2::LUC produces greater suppression of CLOCK:BMAL1 E-box activity than PER2. mPer2Luc carries a 72 bp deletion in exon 23 of Per2, and retains a neomycin resistance cassette that affects rhythm amplitude but not period. The results show that mPer2Luc acts as a circadian clock mutation illustrating a need for detailed assessment of potential impacts of c-terminal tags in genetically modified animal models.
时钟基因 Per2 的修饰显著改变了 mPer2Luc 报告小鼠的昼夜节律功能。在持续黑暗中，行为周期延长，并在持续光照下分为两个明显的成分。节律表现出更高的双峰性，对光脉冲的相位重置增强，以及对定时喂养的适应改变。机制数学模型预测，与修饰的 mPER2 C 末端的增强蛋白相互作用，加上 SCN 亚区之间的时钟调节差异，可以通过增加 Per2 转录本和蛋白质稳定性来解释对昼夜节律行为的影响。PER2::LUC 比 PER2 对 CLOCK:BMAL1 E-box 活性的抑制作用更大。mPer2Luc 在 Per2 的外显子 23 中缺失 72 个碱基对，并保留一个新霉素抗性盒，该抗性盒影响节律幅度而不影响周期。结果表明，mPer2Luc 作为昼夜节律钟突变起作用，这表明需要详细评估遗传修饰动物模型中 C 末端标签的潜在影响。
