Collagenase degradation in extracellular matrix in aging

衰老过程中细胞外基质中胶原酶的降解

• 批准号: 7455845
• 负责人: GARY J FISHER
• 金额: $ 26.69万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-15 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7455845
• 关键词: Address; Adhesions; Age; Aging; Aging-Related Process; Antioxidants; Applications Grants; Biology; Blast Cell; Classification; Collagen; Collagen Fibril; Collagen Type I; Complex; Connective Tissue; Coupled; Data; Dependence; Dermal; Dermis; Enzymes; Equilibrium; Extracellular Matrix; Feedback; Fibrillar Collagen; Fibroblasts; Health; Heart; Human; Individual; Integrin alpha2beta1; Integrins; Interstitial Collagenase; JUN gene; Joints; Lung; MAPK8 gene; Measurement; Measures; Mechanics; Mediating; Mediator of activation protein; Modeling; Molecular; Molecular Analysis; Morbidity - disease rate; Motion; Organ; Pathway interactions; Population; Protein Overexpression; Proteins; Public Health; Reactive Oxygen Species; Regulation; Regulatory Pathway; Role; Sampling; Skin; Skin Aging; Structural Protein; Testing; Therapeutic; Transcript; Transcription Factor AP-1; Transforming Growth Factors; Work; age group; age related; aged; base; body system; bone; collagenase; design; enzyme activity; functional disability; human TGFB1 protein; improved; in vivo

DESCRIPTION (provided by applicant): Human skin, like all other organs, undergoes alterations as a consequence of aging. Reduced function of aged skin is largely caused by irreversible destruction of fibrillar collagen, the major structural protein in skin connective tissue (dermis). As the US population ages, morbidity from loss of collagen decline of skin connective tissue function is becoming an increasing public health concern. The long-term objective of this grant application is to understand molecular mechanisms that are responsible for degradation of fibrillar collagen during aging, and thereby develop preventative and therapeutic remedies to improve the health of aged human skin. We have found that matrix metalloproteinase-1 (MMP-1), the enzyme responsible for initiating cleavage of fibrillar collagen is significantly elevated in aged (>80 years old), compared to young (18-29 years old) human skin dermal fibroblasts in vivo. Overproduction of MMP-1 by dermal fibroblasts causes fragmentation and disorganization of collagen fibrils. This loss of structural integrity of collagen fibrils is a critical factor in the age-related functional impairment of human skin connective tissue. The specific focus of this grant application is to investigate molecular mechanisms that cause this age-dependent MMP-1 overexpression in human skin connective tissue. Based on our preliminary data obtained by direct measurements of young and aged human skin, we hypothesize that elevated MMP-1 levels in aged connective tissue results from the interdependent actions of four MMP-1 regulators: 1) transcription factor AP-1, 2) alpha2beta1 integrin, 3) transforming growth factor-beta1, and 4) reactive oxygen species. These four factors are coordinately regulated through mechanical tension exerted on dermal fibroblasts by its physical interactions with the collagenous extracellular matrix of skin connective tissue, in which they reside. MMP-1-mediated collagen fibril fragmentation results in weakened mechanical tension within dermal fibroblasts. This weakened mechanical tension promotes further expression of MMP-1, and thereby sets in motion a positive feedback pathway of skin connective tissue destruction. Our specific aims are designed to test this working model, using two experimental approaches; 1) direct measurements of relevant transcripts, proteins, and enzyme activities in small samples of human skin from individuals of different age groups, and 2) molecular analysis of MMP-1 regulation in a three dimensional collagen lattice fibroblast culture model, which recapitulates the salient features of MMP-1 overexpression observed in aged human skin connective tissue in vivo. By using these two experimental approaches in a systematic integrated manner, we will investigate the aging process directly in human's largest organ, skin. Given that connective tissue biology is similar throughout the body, our results will likely be directly applicable to many organ systems, including lung, bone, joints, and heart. In addition to testing our hypothesis regarding the mechanism of age-dependent regulation of MMP-1, our proposed studies will provide direct quantitative measures that address the question of "when does aging begin?", as it pertains to human skin connective tissue.

描述（由申请人提供）：人类皮肤与所有其他器官一样，会因衰老而发生变化。老化皮肤功能下降主要是由于纤维状胶原蛋白（皮肤结缔组织（真皮）中的主要结构蛋白）的不可逆破坏造成的。随着美国人口老龄化，胶原蛋白流失和皮肤结缔组织功能下降导致的发病率正成为日益严重的公共卫生问题。这项拨款申请的长期目标是了解衰老过程中纤维状胶原蛋白降解的分子机制，从而开发预防和治疗方法来改善老年人皮肤的健康。我们发现，与年轻（18-29 岁）人类皮肤真皮成纤维细胞相比，基质金属蛋白酶-1（MMP-1）（负责启动纤维状胶原蛋白裂解的酶）在老年人（> 80 岁）中显着升高。体内。真皮成纤维细胞过度产生 MMP-1 会导致胶原纤维断裂和混乱。胶原纤维结构完整性的丧失是人类皮肤结缔组织与年龄相关的功能损伤的关键因素。本次拨款申请的具体重点是研究导致人类皮肤结缔组织中这种年龄依赖性 MMP-1 过度表达的分子机制。根据我们通过直接测量年轻人和老年人皮肤获得的初步数据，我们假设老年结缔组织中 MMP-1 水平升高是由四种 MMP-1 调节因子相互依赖的作用造成的：1) 转录因子 AP-1, 2) α2β1 整合素，3) 转化生长因子-β1，和 4) 活性氧。这四个因素通过真皮成纤维细胞与它们所在的皮肤结缔组织的胶原细胞外基质的物理相互作用而施加在真皮成纤维细胞上的机械张力来协调调节。 MMP-1 介导的胶原纤维断裂导致真皮成纤维细胞内的机械张力减弱。这种减弱的机械张力促进 MMP-1 的进一步表达，从而启动皮肤结缔组织破坏的正反馈途径。我们的具体目标是使用两种实验方法来测试这个工作模型； 1) 直接测量不同年龄组的人体皮肤小样本中的相关转录本、蛋白质和酶活性，以及​​ 2) 在三维胶原晶格成纤维细胞培养模型中对 MMP-1 调节进行分子分析，概括了显着的特点在体内老化人皮肤结缔组织中观察到的 MMP-1 过度表达的特征。通过系统集成的方式使用这两种实验方法，我们将直接研究人类最大的器官——皮肤的衰老过程。鉴于结缔组织生物学在整个身体中是相似的，我们的结果可能直接适用于许多器官系统，包括肺、骨、关节和心脏。除了检验我们关于 MMP-1 年龄依赖性调节机制的假设之外，我们提出的研究还将提供直接的定量测量，以解决“衰老何时开始？”的问题，因为它与人类皮肤结缔组织有关。