Chromatin conformation capture (4C-seq) from mouse liver. Chromatin conformation capture (4C-seq) from mouse liver

The circadian clock system coordinates metabolic, physiological, and behavioral functions across a 24-hour cycle, crucial for adapting to environmental changes. Disruptions in circadian rhythms contribute to major metabolic pathologies like obesity and Type 2 diabetes. Understanding the regulatory mechanisms governing circadian control is vital for identifying therapeutic targets. It is well characterized that chromatin remodeling at distal enhancer elements shapes the genome topology, supporting rhythmic transcriptional cycles; yet the impact of rhythmic chromatin topology and circadian enhancers in disease states is largely unexplored. In his study, we use 4C-seq techniques in mouse liver to explore how the spatial configuration of the genome adapts to diet, rewiring circadian transcription and contributing to dysfunctional metabolism. We describe daily fluctuations in chromatin contacts between distal regulatory elements of metabolic control genes in livers from lean and obese mice and identify specific lipid-responsive regions recruiting the clock molecular machinery. Our findings highlight the intricate coupling of circadian gene expression to a dynamic nuclear environment under high-fat feeding, supporting a temporally regulated program of gene expression and transcriptional adaptation to diet. Overall design: Chromatin conformation capture (4C-seq) from mouse liver was used to asses genomic contacts engaged by regulatory elements from the Dbp, Srepbp1c, Ppara and Pparg2 genes. Mice were fed either a control or a high fat diets and livers were harvested at two circadian time points: ZT6 and ZT18. Two biological replicates were used per condition.

昼夜节律钟系统（circadian clock system）能够在24小时周期内协调代谢、生理及行为功能，对生物体适应环境变化至关重要。昼夜节律紊乱可引发肥胖、2型糖尿病等重大代谢性疾病。阐明调控昼夜节律的分子机制，对于筛选治疗靶点具有关键意义。现有研究表明，远端增强子区域的染色质重塑可塑造基因组拓扑结构，维持节律性转录循环；但节律性染色质拓扑结构与昼夜节律增强子在疾病状态下的作用，目前仍未得到充分研究。本研究采用4C-seq技术，以小鼠肝脏为模型，探究基因组空间构象如何响应饮食调控，重塑昼夜节律转录过程并导致代谢功能异常。本研究分析了瘦鼠与肥胖小鼠肝脏中代谢调控基因远端调控元件之间的染色质接触的每日波动情况，并鉴定出可招募节律钟分子装置的特异性脂质响应区域。研究结果揭示，高脂喂养条件下，昼夜节律基因表达与动态核环境之间存在复杂的耦合关系，印证了基因表达的时序调控程序以及转录层面的饮食适应性机制的存在。实验设计：本研究通过小鼠肝脏染色质构象捕获（4C-seq）技术，分析Dbp、Srepbp1c、Ppara及Pparg2基因调控元件所介导的基因组接触事件。实验小鼠分别饲喂对照饮食与高脂饮食，并在两个昼夜节律时间点ZT6与ZT18采集肝脏样本；每个实验条件设置两个生物学重复。