Procollagen Binding Proteins in Age-Dependent LV Remodeling

年龄依赖性左心室重塑中的原胶原结合蛋白

基本信息

批准号：
8795683
负责人：
Amy D Bradshaw
金额：
--
依托单位：
RALPH H JOHNSON VA MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-04-01 至 2016-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8795683
关键词：
Activities of Daily Living Address Affect Age Aging Animals Binding Binding Proteins Binding Sites Cardiac Cardiovascular Diseases Cell Aging Cell Proliferation Clinical Collagen Collagen Receptors Competitive Binding Cysteine Data Deposition Development Elderly Enzymes Equilibrium Exercise Extracellular Matrix Fibrillar Collagen Fibroblasts Functional disorder Funding Gelatinase A Geometry Heart Heart Diseases Heart failure Hypertension In Vitro Incidence Ischemia Label Left Left Ventricular Mass Left Ventricular Remodeling Left ventricular structure Matrix Metalloproteinases Measurement Measures Mediating Mediator of activation protein Mus Myocardial Myocardium Osteonectin Outcome Patient Care Management Phenotype Phosphorylation Process Procollagen Production Proline Protein Tyrosine Kinase Proteins Radio Radiolabeled Regulation Relative (related person)Signal Pathway Stream Structure Surface Techniques Testing Tissues Transgenic Organisms Ventricular Veterans age effect age related aged base cell age discoidin domain receptor 2 gain of function improved in vivo indexing interstitial loss of function novel older patient programs radiotracer receptor research study senescence

项目摘要

DESCRIPTION (provided by applicant): Left ventricular (LV) structural remodeling, such as changes in LV mass, volume, and geometry, are important predictors of adverse functional and clinical outcomes. Advancing age, independent of concurrent cardiovascular disease, can be associated with significant LV remodeling. Studies in aged animals have shown that increasing age is associated with development of LV concentric remodeling, increased extracellular matrix (ECM) fibrillar collagen content, and significant abnormalities in diastolic function. However, cellular mechanisms by which advanced age leads to cardiac remodeling, particularly a net increase in myocardial collagen content and the development of diastolic dysfunction, have not been completely defined. Regulation of the structure and composition of the collagenous ECM of the myocardium is controlled by cardiac fibroblasts and is regulated at the levels of procollagen synthesis, post-synthetic procollagen processing, and collagen degradation. In aged animals, collagen synthesis is decreased, procollagen processing is increased, and mediators of collagen degradation are generally decreased. In addition, aged fibroblasts demonstrate reduced rates of proliferation consistent with a senescent fibroblast phenotype. In the previous funding period, we identified that expression of SPARC (Secreted Protein Acidic and Rich in Cysteine/osteonectin/BM40), a collagen-binding matricellular protein, was increased in aged myocardium and is a critical factor contributing to elevated collagen content in aged hearts. We also found that SPARC acts to decrease procollagen interaction with cardiac fibroblasts, presumably through decreased engagement of transmembrane collagen receptors. Based on preliminary data, we have identified Discoidin Domain Receptor 2 (DDR2) as a principle collagen receptor engaged in binding collagen and acting in opposition to SPARC. Because DDR2 and SPARC share the same binding site on procollagen, we propose that, in aged myocardium, increases in SPARC expression reduce DDR2 binding to procollagen thus limiting DDR2 binding activity and down-stream signaling pathways. Procollagen binding to DDR2 has been demonstrated to induce fibroblast proliferation and increase production of matrix metalloproteinases (MMP) -2 and -13. Decreased DDR2 activity in aged myocardium is therefore predicted to decrease fibroblast proliferation and production of MMP-2 and -13 thus contributing to the senescent phenotype indicative of aged cardiac fibroblasts. In Aim 1, we will determine whether reductions in DDR2 activity contribute to decreased proliferation and decreased expression of MMP-2 and 13 in aged fibroblasts and whether DDR2 activity is enhanced by decreasing SPARC expression in aged cells. Experiments in Aim 2 will test whether increasing DDR2 activity in aged myocardium, either through over-expression of DDR2 or inhibition of SPARC expression, reverses the senescent fibroblast phenotype in vivo through increasing fibroblast proliferation and production of MMP-2 and 13. Previous studies that have addressed indices of procollagen processing and degradation in aged myocardium have been based primarily on indirect measurements of these processes such as levels of enzymes that process or degrade collagen. In Aim 3, newly developed in vivo radiolabeling techniques will be used to directly quantify changes in procollagen processing and degradation in aged myocardium and determine whether altering DDR2 or SPARC activity influences these processes.

描述（由申请人提供）：左心室（LV）结构重塑，例如LV质量，体积和几何形状的变化，是不良功能和临床结果的重要预测指标。与并发性心血管疾病无关的年龄可能与大量的LV重塑有关。对年龄动物的研究表明，增加年龄与LV同心重塑的发展有关，细胞外基质（ECM）纤维胶原蛋白含量增加以及舒张功能的显着异常。但是，尚未完全定义高级年龄导致心脏重塑的细胞机制，尤其是心肌胶原蛋白含量的净增加和舒张功能障碍的发展。心肌胶原性ECM的结构和组成的调节受心脏成纤维细胞控制，并在胶原蛋白合成，合成后的procollagen加工和胶原蛋白降解的水平下进行调节。在老年动物中，胶原蛋白合成减少，胶原蛋白加工增加，胶原蛋白降解的介质通常会降低。此外，老化的成纤维细胞表明，与衰老成纤维细胞表型一致的增殖率降低。在上一个资金期间，我们确定了SPARC（分泌蛋白酸性和富含半胱氨酸/抗抑制素/BM40）的表达是一种胶原蛋白结合的矩阵蛋白，在老化的心肌中增加，并且是老化心脏中升高的胶原含量的关键因素。我们还发现，SPARC的作用可减少与心脏成纤维细胞的相互作用，这可能是通过跨膜胶原受体的参与度降低。基于初步数据，我们已经将盘状结构域受体2（DDR2）确定为参与结合胶原蛋白并与SPARC作用的原理胶原蛋白受体。由于DDR2和SPARC在Procollagen上共享相同的结合位点，因此我们建议，在年龄的心肌中，SPARC表达的增加减少了DDR2与Procollagen的结合，从而限制了DDR2结合活性和下游信号传导途径。已证明了与DDR2的胶原素结合可诱导成纤维细胞增殖并增加基质金属蛋白酶（MMP）-2和-13的产生。因此，预计老年心肌中DDR2活性的降低将降低成纤维细胞增殖和MMP -2和-13的产生，从而导致衰老表型，指示了衰老的心脏成纤维细胞。在AIM 1中，我们将确定DDR2活性的降低是否有助于衰老成纤维细胞中MMP-2和13的表达降低，以及是否通过降低老化细胞的SPARC表达来增强DDR2活性。 AIM 2中的实验将测试是否通过过度表达DDR2或抑制SPARC表达来增加DDR2活性是否会增加体内衰老成纤维细胞表型，从而逆转衰老成纤维细胞表型，通过增加成纤维细胞的增殖和MMP-2和13的产生。间接测量这些过程，例如过程或降解胶原蛋白的酶水平。在AIM 3中，新开发的体内放射标记技术将用于直接量化老年心肌的Procollagen加工和降解的变化，并确定改变DDR2或SPARC活性是否会影响这些过程。