Division of Metabolic Endocrinology, Department of Zoology, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, India.
Department of Internal Medicine, University of Michigan, Ann Arbor, MI, United States of America.
PLoS One. 2023 Aug 10;18(8):e0283591. doi: 10.1371/journal.pone.0283591. eCollection 2023.
Altered circadian rhythms underlie manifestation of several cardiovascular disorders, however a little is known about the mediating biomolecules. Multiple transcriptional-translational feedback loops control circadian-clockwork wherein; micro RNAs (miRNAs) are known to manifest post transcriptional regulation. This study assesses miR34a-5p as a mediating biomolecule.
8-10-week-old male C57BL/6J mice (n = 6/group) were subjected to photoperiodic manipulation induced chronodisruption and thoracic aortae were examined for miRNA, gene (qPCR) and protein (Immunoblot) expression studies. Histomorphological changes were assessed for pro-atherogenic manifestations (fibrillar arrangement, collagen/elastin ratio, intima-media thickening). Computational studies for miRNA-mRNA target prediction were done using TargetScan and miRDB. Correlative in vitro studies were done in serum synchronized HUVEC cells. Time point based studies were done at five time points (ZT 0, 6, 12, 18, 24) in 24h.
Chronodisruption induced hypomethylation in the promoter region of miR34a-5p, in the thoracic aortae, culminating in elevated miRNA titers. In a software-based detection of circadian-clock-associated targets of miR34a-5p, Clock and Sirt1 genes were identified. Moreover, miR34a-5p exhibited antagonist circadian oscillations to that of its target genes CLOCK and SIRT1 in endothelial cells. Luciferase reporter gene assay further showed that miR34a-5p interacts with the 3'UTR of the Clock gene to lower its expression, disturbing the operation of positive arm of circadian clock system. Elevated miR34a-5p and impeded SIRT1 expression in a chronodisruptive aortae exhibited pro-atherogenic changes observed in form of gene expression, increased collagen/elastin ratio, fibrillar derangement and intimal-media thickening.
The study reports for the first time chronodisruption mediated miR34a-5p elevation, its circadian expression and interaction with the 3'UTR of Clock gene to impede its expression. Moreover, elevated miR34a-5p and lowered SIRT1 expression in the chronodisruptive aortae lead off cause-consequence relationship of chronodisruption mediated proatherogenic changes.
昼夜节律的改变是几种心血管疾病表现的基础，然而关于介导生物分子的了解甚少。多个转录-翻译反馈回路控制着生物钟，其中已知 microRNAs（miRNAs）可进行转录后调节。本研究评估了 miR34a-5p 作为一种介导生物分子。
将 8-10 周龄雄性 C57BL/6J 小鼠（n = 6/组）进行光周期操作诱导的生物钟扰乱，并检查胸主动脉的 miRNA、基因（qPCR）和蛋白质（免疫印迹）表达研究。进行组织形态学变化评估以检测动脉粥样硬化前表现（纤维状排列、胶原/弹性蛋白比、内膜-中膜增厚）。使用 TargetScan 和 miRDB 进行 miRNA-mRNA 靶标预测的计算研究。在血清同步化的 HUVEC 细胞中进行相关的体外研究。在 24 小时内的五个时间点（ZT0、6、12、18、24）进行基于时间点的研究。
生物钟扰乱导致 miR34a-5p 启动子区域的低甲基化，导致胸主动脉中的 miRNA 滴度升高。在基于软件的 miR34a-5p 与昼夜节律相关靶基因的检测中，鉴定出 Clock 和 Sirt1 基因。此外，miR34a-5p 在血管内皮细胞中表现出与其靶基因 CLOCK 和 SIRT1 的相反昼夜节律波动。荧光素酶报告基因检测进一步表明，miR34a-5p 与 Clock 基因的 3'UTR 相互作用以降低其表达，从而扰乱昼夜节律系统的正臂运转。在生物钟扰乱的主动脉中，miR34a-5p 的升高和 SIRT1 表达的抑制导致观察到的基因表达、胶原/弹性蛋白比增加、纤维状排列紊乱和内膜-中膜增厚等动脉粥样硬化前变化。
本研究首次报道了生物钟扰乱介导的 miR34a-5p 升高、其昼夜节律表达以及与 Clock 基因 3'UTR 的相互作用，从而抑制其表达。此外，在生物钟扰乱的主动脉中，miR34a-5p 的升高和 SIRT1 表达的降低导致生物钟扰乱介导的动脉粥样硬化前变化的因果关系。
