Control of aging and age-related diseases by extracellular matrix microenvironment

摘要 老龄化是造成公共卫生负担的许多常见疾病的最大风险因素。这个项目的主要目标是 应用是了解由皮肤的有害改变引起的与年龄有关的疾病的发病机制， 细胞外基质（ECM）微环境。本申请采用了新的小鼠模型的加速皮肤 结缔组织老化，因此解决了NIH确定的开发和表征 衰老研究的动物模型（FOA PA-13-155）。 真皮构成皮肤的主体并赋予强度和弹性。真皮主要由 胶原ECM。这种ECM由成纤维细胞产生、组织和维持。我们最近的研究表明， 在体内老化的人皮肤中，成纤维细胞表达升高水平的称为CCN 1的蛋白质。我们发现CCN 1的升高 导致成纤维细胞表达大量分泌蛋白质的水平改变，这些蛋白质有害地影响皮肤功能。 CCN 1诱导的改变包括：1）胶原蛋白产生减少，这导致皮肤变薄; 2）胶原蛋白水平升高， 胶原降解酶，其引起ECM片段化;和3）促炎细胞因子水平增加， 其促进与老化相关的炎症（炎症）。重要的是，这些CCN 1诱导的变化是主要的 人体皮肤老化的特征。我们将这些改变统称为“皮肤相关微环境 （AADM）"。 基于这些数据，我们通过以下方法建立了CCN 1表达增加的转基因小鼠模型（CCN 1col-tg）： 成纤维细胞这些小鼠显示加速老化和AADM。此外，这些小鼠表现出显著增加的 易形成皮肤肿瘤。根据我们的研究结果，我们假设年龄相关的CCN 1升高， 真皮成纤维细胞引起AADM，其促进皮肤老化和与年龄相关的皮肤病。 具体目标1将检验健康年轻皮肤微环境作为肿瘤抑制因子的假设， AADM作为肿瘤促进剂。具体目标2将确定CCN 1促进的分子机制， AADM具体目标3将利用基于机制的干预来抑制CCN 1诱导的AADM和皮肤癌 阵 该提案是创新的，并且具有高度影响力，因为它：1）利用新颖的小鼠模型来研究新的概念， 衰老，即AADM及其在衰老和与年龄相关的疾病中的作用，以及2）使人们关注相互作用的重要性， 细胞外微环境与衰老过程中细胞功能下降之间的关系。

ABSTRACT Aging is the single largest risk factor for many common diseases that burden public health. The major goal of this application is to understand the pathogenesis of age-related diseases resulting from deleterious alterations of the dermal extracellular matrix (ECM) microenvironment. This application employs novel mouse models of accelerated skin connective tissue aging and therefore addresses a need identified by the NIH for development and characterization of animal models for aging research (FOA PA-13-155). The dermis comprises the bulk of skin and confers strength and resiliency. The dermis is primarily composed of collagenous ECM. This ECM is produced, organized and maintained by fibroblasts. Our recent studies reveal that dermal fibroblasts, in aged human skin in vivo, express elevated levels of a protein called CCN1. We find that elevated CCN1 causes fibroblasts to express altered levels of numerous secreted proteins that deleteriously impact skin function. CCN1-induced alterations include: 1) reduced collagen production, which causes dermal thinning; 2) elevated levels of collagen-degrading enzymes, which cause ECM fragmentation; and 3) increased levels of proinflammatory cytokines, which promote aging associated inflammation (inflammaging). Importantly, these CCN1-induced alterations are major features of aged human skin. We refer collectively to these alterations as “Age-Associated Dermal Microenvironment (AADM)”. Based on these data, we have created a transgenic mouse model (CCN1col-tg) with increased expression of CCN1 by fibroblasts. These mice display accelerated aging and AADM. In addition, these mice exhibit significantly increased susceptibility to formation of skin tumors. Based on our findings, we hypothesize that age-related elevation of CCN1 by dermal fibroblasts causes AADM, which promotes skin aging and age-related skin diseases. Specific Aim 1 will test the hypothesis that healthy young dermal microenvironment functions as tumor suppressor, while AADM act as a tumor promoter. Specific Aim 2 will determine molecular mechanisms by which CCN1 promotes AADM. Specific Aim 3 will utilize mechanism-based intervention to inhibit CCN1-induced AADM and skin cancer formation. This proposal is innovative and highly impactful because it: 1) utilizes novel mouse models to investigate new concepts of aging, i.e. AADM and its role in aging and age-related diseases, and 2) brings into focus the importance of the interplay between the extracellular microenvironment and decline of cell function during the aging process.