Circadian rhythms are characterized as oscillations that fluctuate based on a 24 h cycle and are responsible for regulation of physiological functions. While the internal clock synchronizes gene expression using external cues like light, a similar synchronization can be induced in vitro by incubating the cells with an increased percentage of serum followed by its rapid removal. Previous studies have suggested that synchronization of HepG2 cell line induced the rhythmic expression of drug-metabolizing enzymes (DME) most specifically the cytochrome P450 enzymes. However, there is a lack of evidence demonstrating the influence of three-dimensional microenvironment on the rhythmicity of these genes. To understand this interplay, gene expression of the circadian machinery and CYP450s were compared using the model human hepatocarcinoma cell line, HepG2. Upon serum shock synchronization, gene and protein expression of core clock regulators was assessed and rhythmic expression of these genes was demonstrated. Further insight into the interrelations between various gene pairs was obtained using statistical analysis. Using RNA sequencing, an in-depth understanding of the widespread effects of circadian regulation on genes involved in metabolic processes in the liver was obtained. This study aids in the better understanding of chronopharmacokinetic events in humans using physiologically relevant 3D culture systems.

中文翻译：

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昼夜节律对 3D 肝球体药物代谢的影响

昼夜节律的特征是基于 24 小时周期波动的振荡，并负责调节生理功能。虽然内部时钟使用外部信号（如光）同步基因表达，但通过将细胞与更高百分比的血清孵育，然后快速去除血清，可以在体外诱导类似的同步。先前的研究表明，HepG2 细胞系的同步诱导药物代谢酶 (DME) 的节律性表达，最特别是细胞色素 P450 酶。然而，缺乏证据证明三维微环境对这些基因节律性的影响。为了了解这种相互作用，使用模型人肝癌细胞系 HepG2 比较了昼夜节律机制和 CYP450 的基因表达。在血清休克同步后，评估了核心时钟调节器的基因和蛋白质表达，并证明了这些基因的节律性表达。使用统计分析进一步了解各种基因对之间的相互关系。使用 RNA 测序，深入了解昼夜节律调节对参与肝脏代谢过程的基因的广泛影响。这项研究有助于使用生理相关的 3D 培养系统更好地了解人类的时间药代动力学事件。获得了对昼夜节律调节对参与肝脏代谢过程的基因的广泛影响的深入了解。这项研究有助于使用生理相关的 3D 培养系统更好地了解人类的时间药代动力学事件。获得了对昼夜节律调节对参与肝脏代谢过程的基因的广泛影响的深入了解。这项研究有助于使用生理相关的 3D 培养系统更好地了解人类的时间药代动力学事件。