Regulation of Blood Pressure Circadian Rhythm by Vascular Smooth Muscle BMAL1

描述(申请人提供)：众所周知的血压(BP)昼夜节律对人类健康很重要，糖尿病患者的BP昼夜节律紊乱正在成为未来靶器官损害和心血管结果的指标。最近的发现，时钟基因在所有被检查的组织中都有表达，这对血压昼夜节律完全由中枢起搏器控制的教条提出了挑战。然而，在外周组织(S)中，哪个特定的时钟基因(S)对血压昼夜节律起重要作用，这是完全未知的。我们创造了一个新的平滑肌特异性时钟基因BMAL1基因敲除小鼠SM-BMal1-/-，以研究生理和糖尿病条件下血管平滑肌在血压昼夜节律中的作用。我们发现BMAL1对于正常的血压昼夜节律以及正常的血管平滑肌收缩昼夜节律变化都是必不可少的。此外，我们的初步研究表明，Rho激酶ROCK2将BMAL1与收缩联系在一起。重要的是，我们发现，在2型糖尿病db/db小鼠中，BMAL1蛋白的丢失和活动的昼夜振荡与血管平滑肌昼夜节律的丧失和血压昼夜节律的丧失有关。因此，我们假设BMAL1调节ROCK2，从而控制血管平滑肌收缩昼夜节律的变化，从而显著促进正常的血压昼夜节律及其在糖尿病中的破坏。我们建议使用体外和体内的方法来检验这一假说，具体目的有三：1)检验在生理条件下，BMAL1通过ROCK2调节血管平滑肌收缩昼夜节律变化和血压昼夜节律的假说。2)测试假设，在糖尿病条件下，BMAL1是打破血管平滑肌收缩昼夜节律变化所必需的。3)确定血管平滑肌BMAL1在糖尿病相关血压昼夜节律紊乱中的作用。这项研究的结果可能会改变中央起搏器单独负责生理血压昼夜节律的教条，为外周血管平滑肌BMAL1发挥重要作用提供第一个直接的实验证据。此外，我们的结果可能确定血管平滑肌BMAL1作为控制糖尿病患者24小时血压的潜在治疗靶点，因为它提供了证据 BMal1是将糖尿病与血压昼夜节律紊乱联系起来的一个重要因素。

DESCRIPTION (provided by applicant): The well-known blood pressure (BP) circadian rhythm is important to human health and BP circadian rhythm disruption in diabetes is emerging as an index for future target organ damage and cardiovascular outcomes. Recent discoveries that clock genes are expressed in all of the tissues examined challenges the dogma that BP circadian rhythm is solely controlled by central pacemaker. However, it is completely unknown which specific clock gene(s) in which peripheral tissue(s) are important for BP circadian rhythm. We have generated a novel smooth muscle specific clock gene BMAL1 knockout mice SM-bmal1-/- to investigate the role of vascular smooth muscle in BP circadian rhythm under physiological and diabetic conditions. We found that vascular smooth muscle BMAL1 is essential for normal BP circadian rhythm as well as normal vascular smooth muscle contractile circadian variation. Moreover, our preliminary study implicates rho kinase, ROCK2, links BMAL1 to contraction. Importantly, we found that, in type 2 diabetic db/db mice, loss of BMAL1 protein and activity circadian oscillations is associated with loss of vascular smooth muscle circadian variation and BP circadian rhythm. Thus we hypothesize that BMAL1 regulates ROCK2, thus controlling vascular smooth muscle contractile circadian variation, thereby significantly contributing to normal BP circadian rhythm and its disruption in diabetes. We propose to use in vitro and in vivo approaches to test the hypothesis in three specific aims: 1) test the hypothesis that, under physiological conditions, BMAL1 regulates the vascular smooth muscle contractile circadian variation and BP circadian rhythm via ROCK2. 2) Test the hypothesis that, under diabetic conditions, BMAL1 is required for disruptions in vascular smooth muscle contractile circadian variation. 3) Determine the role of vascular smooth muscle BMAL1 in diabetes-associated disruption of BP circadian rhythm. Results from the proposed studies may modify the dogma that central pacemaker is solely responsible for the physiological BP circadian rhythm by providing the first direct experimental evidence that peripheral vascular smooth muscle BMAL1 play an important role. Moreover, our results may identify vascular smooth muscle BMAL1 as a potential therapeutic target for control of 24-h BP in diabetic patients by providing evidence that BMAL1 is a significant contributor linking diabetes to disruptions of BP circadian rhythm.