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.

这项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，就像所有的人体器官一样，会因为 时间的流逝。皮肤的自然老化主要表现为皮肤变薄，主要是由于I型皮肤的丧失 真皮中的胶原蛋白。I型胶原是皮肤中含量最丰富的蛋白质，它赋予皮肤结构、力量 和韧性。与年龄相关的胶原蛋白丢失会导致皮肤更脆弱，从而使皮肤更 容易擦伤，阻碍伤口愈合。美国人口老龄化使医疗保健变得脆弱 皮肤是一个日益严重的公共卫生问题。皮肤除了是人类最大的器官外，还很容易接触到 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物种(ROS)氧化而成。 我们发现在活体内老化的人皮肤成纤维细胞中ROS水平升高。成纤维细胞是主要的细胞 产生I型胶原蛋白的类型。此外，我们还发现转化生长因子-β/SMAD/CTGF轴是主要的 在皮肤中驱动I型胶原产生的调节网络在老年人皮肤中受到损害。这 损伤是由于Smad3表达减少所致，Smad3是转化生长因子-β作用的下游效应因子。 结缔组织生长因子(CTGF)的表达减少，CTGF是一种多功能蛋白质，起作用 与转化生长因子-β协同调节I型胶原的表达。此外，我们发现，温和的、短期的 原代培养的人真皮成纤维细胞氧化暴露可引起永久性细胞改变， 与体内老化皮肤成纤维细胞中观察到的相似，即ROS增加，Smad3减少， CTGF减少，I型胶原表达减少。基于这些观察，我们假设 ROS增加，Smad3和CTGF表达减少，从而导致I型胶原减少 在老化的人类皮肤中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、Smad3、CTGF和I型胶原产生的年龄相关变化 体内成纤维细胞，2)测定局部抗氧化剂降低ROS水平，减轻损伤的能力 在活体老年人皮肤中的转化生长因子-β/SMAD/CTGF轴，并诱导I型胶原的产生，3)确定 氧化暴露降低Smad3、CTGF和I型胶原表达的分子机制 4)确定CTGF调控I型胶原的分子机制 表情。拟议的研究结果将提供关于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 调节转化生长因子β/SMAD/CTGF轴，以及4)CTGF与转化生长因子β在 I型胶原表达的调控。