Regulation of Extracellular Matrix Homeostatsis in Skin Aging

皮肤衰老过程中细胞外基质稳态的调节

• 批准号: 8512628
• 负责人: GARY J FISHER
• 金额: $ 28.48万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-15 至 2014-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8512628
• 关键词: Age of Onset; Aging; Antioxidants; Behavior Control; Biochemical; Blood Vessels; Caring; Cell Culture Techniques; Cell Respiration; Cells; Collagen; Collagen Type I; Connective Tissue; Controlled Environment; Contusions; Data; Dermal; Dermis; Elderly; Epidermis; Epithelium; Extracellular Matrix; Extracellular Matrix Proteins; Fibroblasts; Free Radicals; Goals; Hair follicle structure; Human; Immune; Impairment; MADH3 gene; Mechanics; Mediating; Medical; Molecular; Nerve; Neurons; Organ; Pathway interactions; Population; Production; Property; Proteins; Public Health; Reactive Oxygen Species; Regulation; Research; Sebaceous Glands; Signal Pathway; Signal Transduction; Skiing; Skin; Skin Aging; Smooth Muscle Myocytes; Structural Protein; Structure; Study models; Sweat Glands; Testing; Time; Type I Procollagen; Wound Healing; age related; aged; appendage; base; cell behavior; cell type; connective tissue growth factor; in vivo; insight; oxidation; theories

The long-term goal of the proposed research is to understand molecular basis and functional impact of skin connective tissue aging. Skin, like all human organs, undergoes deleterious alterations as a consequence of the passage of time. Natural aging of skin is manifested primarily by thinning, largely due to loss of type I collagen in the dermis. Type I collagen is the most abundant protein in skin and confers structure, strength and resiliency. Age-dependent loss of collagen causes increased fragility and thereby makes skin more susceptible to bruising and impedes wound healing. Aging of the US population makes medical care of fragile skin a growing public health concern. In addition to being the largest human organ, skin is readily accessible for study. These unique properties of skin provide the opportunity study molecular mechanisms of aging in humans. The free radical theory of aging posits that natural aging is driven by cellular damage that results from oxidation by reactive oxygen species (ROS) that are generated as a consequence of aerobic metabolism. We find that ROS levels are elevated in aged human skin fibroblasts in vivo. Fibroblasts are the major cell type that produces type I collagen. In addition, we find that the TGF-¿/SMAD/CTGF axis, which is the major regulatory network that drives type I collagen production in skin, is impaired in aged human skin. This impairment results from decreased expression of SMAD3, which is a downstream effector of TGF-¿ actions, and reduced expression of connective tissue growth factor (CTGF), which is a multi-functional protein that acts in concert with TGF-¿ to regulate type I collagen expression. Furthermore, we find that mild, short-term oxidative exposure of primary cultured human dermal fibroblasts causes permanent cellular alterations that closely mimic those observed in fibroblasts in aged skin in vivo; namely, increased ROS, reduced SMAD3, reduced CTGF, and reduced type I collagen expression. Based on these observations, we hypothesize that increased ROS, reduces expression of SMAD3 and CTGF, which results in reduction of type I collagen production, in fibroblasts in aged human skin. We propose four Specific Aims to test this hypothesis: 1) determine age-related alterations of ROS, SMAD3, CTGF, and type I collagen production, in human skin fibroblasts in vivo, 2) determine the ability of topical anti-oxidant to reduce ROS levels, mitigate impairment of the TGF-¿/SMAD/CTGF axis, and induce type I collagen production, in aged human skin in vivo, 3) determine molecular mechanisms by which oxidative exposure reduces SMAD3, CTGF and type I collagen expression in human ski fibroblasts, and 4) determine molecular mechanisms by which CTGF regulates type I collagen expression. The results from the proposed studies will provide important insights regarding 1) the age of onset of human skin aging, 2) molecular actions of topical antioxidant, 3) mechanisms by which oxidative exposure regulates the TGF-¿/SMAD/CTGF axis, and 4) molecular basis by which CTGF cooperates with TGF-¿ in the regulation of type I collagen expression.

拟议研究的长期目标是了解皮肤的分子基础和功能影响 结缔组织老化皮肤，像所有的人体器官一样，经历了有害的变化， 时间的流逝皮肤的自然老化主要表现为变薄，主要是由于I型胶原的丧失。 真皮中的胶原蛋白。I型胶原蛋白是皮肤中最丰富的蛋白质， 和弹性。胶原蛋白的依赖性损失会导致脆性增加，从而使皮肤变得更加脆弱。 容易擦伤并阻碍伤口愈合。美国人口老龄化使医疗保健变得脆弱 皮肤是一个日益增长的公共卫生问题。皮肤是人体最大的器官， 为了学习皮肤的这些独特性质为研究衰老的分子机制提供了机会， 人类衰老的自由基理论认为，自然衰老是由细胞损伤引起的， 由有氧代谢产生的活性氧（ROS）氧化而成。 我们发现，活性氧水平升高，在体内老化的人皮肤成纤维细胞。成纤维细胞是主要的细胞 产生I型胶原蛋白。此外，我们发现，TGF-β/SMAD/CTGF轴，这是主要的 驱动皮肤中I型胶原蛋白产生的调节网络在老年人皮肤中受损。这 损伤由SMAD 3表达减少引起，SMAD 3是TGF-β作用的下游效应物， 结缔组织生长因子（CTGF）的表达减少，CTGF是一种多功能蛋白质， 与TGF-β协同调节I型胶原表达。此外，我们发现，温和，短期 原代培养的人皮肤成纤维细胞的氧化暴露引起永久性细胞改变， 与在体内老化皮肤的成纤维细胞中观察到的那些密切相似;即增加的ROS，减少的SMAD 3， CTGF减少和I型胶原蛋白表达减少。基于这些观察，我们假设， ROS增加，SMAD 3和CTGF的表达减少，导致I型胶原减少 在老年人皮肤的成纤维细胞中产生。我们提出了四个具体目标来检验这一假设：1） 确定人皮肤中ROS、SMAD 3、CTGF和I型胶原蛋白产生的年龄相关变化 2）测定局部抗氧化剂降低ROS水平、减轻成纤维细胞损伤的能力， TGF-β/SMAD/CTGF轴，并诱导I型胶原蛋白产生，3）确定 氧化暴露降低SMAD 3、CTGF和I型胶原表达的分子机制 人滑雪成纤维细胞，以及4）确定CTGF调节I型胶原的分子机制 表情拟议研究的结果将提供关于1）发病年龄的重要见解 2）局部抗氧化剂的分子作用，3）氧化暴露的机制， 调节TGF-β/SMAD/CTGF轴，以及4）CTGF与TGF-β在细胞内协同作用的分子基础。 I型胶原表达的调节。