Protection from Aortic Aneurysm by Bmal1 deletion from Smooth Muscle Cells

通过从平滑肌细胞中删除 Bmal1 来预防主动脉瘤

• 批准号: 8720268
• 负责人: Jenny Lutshumba
• 金额: $ 3.11万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-05 至 2016-09-04
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8720268
• 关键词: ARNT gene; Abdominal Aortic Aneurysm; Acetates; Affect; Aneurysm; Angiotensin II; Aorta; Aortic Aneurysm; BHLH Protein; Behavior; Biological Clocks; Blood Pressure; Blood Vessels; Brain; Breeding; Cardiovascular system; Cause of Death; Circadian Rhythms; Data; Deoxycorticosterone; Dilatation - action; Disease; Elderly; Emergency Situation; Extracellular Matrix; Extracellular Matrix Degradation; Gelatinases; Genes; Hypertension; Hypothalamic structure; In Situ; Incidence; Infusion procedures; Inhibition of Matrix Metalloproteinases Pathway; Injury; Knockout Mice; Laboratories; Lead; MMP2 gene; MMP9 gene; Matrix Metalloproteinase Inhibitor; Matrix Metalloproteinases; Mediating; Metalloproteases; Modeling; Molecular; Mus; Muscle; Mutation; Operative Surgical Procedures; Pathology; Patients; Peptide Hydrolases; Peripheral; Pharmaceutical Preparations; Physiology; Play; Proteins; Rattus; Relative (related person); Role; Ruptured Abdominal Aortic Aneurysm; Smooth Muscle; Smooth Muscle Myocytes; Sodium Chloride; Staining method; Stains; Testing; Tissue Inhibitor of Metalloproteinases; Tissues; Up-Regulation; Vascular Diseases; Vascular Smooth Muscle; age related; aging population; design; inhibitor/antagonist; insight; mRNA Expression; male; member; mortality; mouse model; neointima formation; new therapeutic target; novel; prevent; protective effect; protein expression; public health relevance; response; salt sensitive hypertension; suprachiasmatic nucleus; therapeutic target

DESCRIPTION (provided by applicant): Protection from Aortic Aneurysm by Bmal1 deletion from Smooth Muscle Cells Recognized as an important cause of death in the aging population, aortic aneurysm is a disease that is currently treated only through surgery. Therefore, a thorough understanding of the molecular mechanism of aortic aneurysm is a pressing matter. Bmal1 is a basic helix loop helix (bHLH) transcription factor and is an indispensable core clock gene. Bmal1 is expressed in vascular smooth muscle but its function remains mostly unknown.The current study is designed to test a potential role of Bmal1 in aortic aneurysm. Our preliminary data have shown that deletion of Bmal1 from smooth muscle cells has been protective from DOCA plus salt induced aortic aneurysm formation in 8 to 9 months old mice. This protection is independent of increase in blood pressure. We have also found that smooth muscle specific knockout mice have an increase of Tissue inhibitor of mellaproteinases 4(TIMP4) at basal level and a further increase in TIMP4 after DOCA plus salt with no gelatinases activities. TIMP4 is the fourth member of endogenous inhibitors of matrix metalloproteinases (MMPs). TIMP4 expression is restricted to cardiovascular tissues and has been shown to be a strong inhibitor of MMP2. TIMP4 role in aortic aneurysm formation is unknown. MMPs are proteases that degrade component of the extracellular matrix (ECM). Many MMPs have been identified and classified depending on their substrates. An imbalance between MMPs and TIMPs has been shown to be a major cause of vascular diseases such as aortic aneurysm. Gelatinases MMP2 and MMP9 have been shown to be upregulated in patients with aortic aneurysm. Our hypothesis has been that Bmal1 regulates TIMP4 expression therefore, playing a role in aneurysm formation. To test this hypothesis, we have constructed two specific aims: 1) to test the hypothesis that deletion of Bmal1 in smooth muscle cells will protect from other model of aortic aneurysm such as angiotensin II and CaPO4 through TIMP4 upregulation. 2) To test the hypothesis that upregulation of TIMP4 mediates the protective effect observed in SMC-Bmal1 KO mice. To determine whether SMC-Bmal1 KO mice will be protected from other models of aortic aneurysm, we will first induced aortic aneurysm using AngII+salt then compare the relative aortic aneurysm incidence. Second, we will induce aortic aneurysm using CaPO4 in SMC-Bmal1 KO mice. To look at the role of TIMP4 in aortic aneurysm, we will use TIMP4 KO mice and TIMP4-Bmal1 KO mice and induce aortic aneurysm using the DOCA plus salt model which we will then compare the incidence of aortic aneurysm. We will use different staining to distinguish the pathology among the different mice that will be used. The results from this proposed study will provide new insights to the molecular mechanisms underlying aortic aneurysm, and may lead to a new therapeutic target for the aortic aneurysm treatment.

描述（由申请人提供）：BMAL1缺失免受平滑肌细胞的保护免受主动脉动脉瘤的保护，该平滑肌细胞被认为是衰老人群中重要的死亡原因，主动脉动脉瘤是一种目前仅通过手术治疗的疾病。因此，对主动脉瘤的分子机制有透彻的理解是一个紧迫的问题。 BMAL1是基本的螺旋环螺旋（BHLH）转录因子，是必不可少的核心时钟基因。 BMAL1在血管平滑肌中表达，但其功能仍然未知。当前的研究旨在测试BMAL1在主动脉动脉瘤中的潜在作用。我们的初步数据表明，平滑肌细胞中BMAL1的缺失已免受DOCA和盐诱导的主动脉瘤形成8至9个月大的小鼠的保护。这种保护独立于血压升高。我们还发现，平滑肌肉特异性敲除小鼠在基础水平上的麦洛基蛋白酶4（TIMP4）的组织抑制剂增加，而在没有明胶活性的doca加盐后TIMP4的TIMP4进一步增加。 TIMP4是基质金属蛋白酶（MMP）内源性抑制剂的第四个成员。 TIMP4表达仅限于心血管组织，已被证明是MMP2的强抑制剂。 TIMP4在主动脉动脉瘤形成中的作用尚不清楚。 MMP是降解细胞外基质（ECM）的蛋白酶。根据其底物，已经确定并分类了许多MMP。 MMP和TIMP之间的失衡已被证明是血管疾病（例如主动脉瘤）的主要原因。明胶酶MMP2和MMP9已显示出主动脉瘤患者的上调。我们的假设是BMAL1调节TIMP4表达，因此在动脉瘤形成中起作用。为了检验这一假设，我们构建了两个具体的目的：1）测试平滑肌细胞中BMAL1缺失的假设将通过TIMP4上调来保护其他主动脉动脉瘤II和CAPO4等主动脉动脉瘤II和CAPO4。 2）检验以下假设：TIMP4的上调介导SMC-BMAL1 KO小鼠中观察到的保护作用。为了确定SMC-BMAL1 KO小鼠是否会受到其他主动脉瘤模型的保护，我们将首先使用ANGII+盐诱导主动脉瘤，然后比较相对主动脉瘤的发生率。其次，我们将在SMC-BMAL1 KO小鼠中使用CAPO4诱导主动脉瘤。为了查看TIMP4在主动脉动脉瘤中的作用，我们将使用TIMP4 KO小鼠和TIMP4-BMAL1 KO小鼠，并使用DOCA加盐模型诱导主动脉瘤，然后将其比较主动脉动脉瘤的发生率。我们将使用不同的染色来区分将要使用的不同小鼠之间的病理。这项拟议的研究的结果将为主动脉瘤性动脉瘤的分子机制提供新的见解，并可能导致主动脉动脉瘤治疗的新治疗靶点。