YAP/TAZ Regulation of Extracellular Matrix Homeostasis

摘要： 这项资助申请的主要目的是确定YAP/TAZ调节年龄相关的分子机制。 皮肤真皮细胞外基质(ECM)动态平衡。 在人类皮肤中，真皮成纤维细胞负责富含胶原蛋白的产生、组织和动态平衡。 真皮细胞外基质，它构成了皮肤的大部分。在年轻的皮肤中，直接附着在完整的胶原纤维上可以 成纤维细胞通过组装细胞骨架所产生的机械力来实现铺展结构。 在这种状态下，YAP/TAZ途径是活跃的，它保持年轻的合成代谢表型和净ECM产生。在……里面 老化的皮肤，碎裂的胶原纤维不支持成纤维细胞的附着，导致机械力/伸展减少 YAP/TAZ功能下降。在这种状态下，成纤维细胞表现出老化的分解代谢表型，伴随着净ECM降解， 它是自我延续的，并创造了一个促进许多年龄的发病的皮肤微环境- 相关皮肤病。 我们建议研究一种假设，即真皮成纤维细胞中的YAP/TAZ机械感应信号通路是一种 与年龄相关的皮肤ECM动态平衡的关键调节因子。这一数据驱动的假设包含一个关键概念，即 皮肤细胞外基质的动态平衡是由成纤维细胞对周围的细胞外基质微环境的适应所控制的，而不是 而不是细胞自主因子。因此，我们认为真皮细胞外基质动态平衡与真皮的“由外向内适应”有关。 成纤维细胞到与年龄相关的真皮细胞外基质状态，其中嵌入成纤维细胞，这种适应是 受到YAP/TAZ的严格监管。 为了验证上述假设，我们最近建立了两个互补的转基因小鼠模型：1) 真皮成纤维细胞中YAP/Taz的条件性敲除导致新生儿真皮细胞外基质显著受损 成熟与fi显著加速真皮细胞外基质老化；2)人源化小鼠真皮衰老模型 真皮成纤维细胞中降解胶原蛋白的基质金属蛋白酶-1的表达。重要的是，这种模式 显示对ECM降解的YAP/TAZ的生理性失活。 为了检验上述假设，我们提出了以下具体目标： 目的1：确定YAP/TAZ介导真皮ECM动态平衡的分子机制 在出生后的早期生活和时间上的衰老 目的2：确定YAP/TAZ功能恢复对皮肤ECM动态平衡的影响 目的3：探讨年龄相关性YAP/TAZ功能下降的机制。 成纤维细胞“由外向内适应”

ABSTRACT: The major goal of this grant application is to determine the molecular mechanisms by which YAP/TAZ regulate age-related skin dermal extracellular matrix (ECM) homeostasis. In human skin, dermal fibroblasts are responsible for the production, organization, and homeostasis of the collagen-rich dermal ECM, which comprises the bulk of the skin. In young skin, direct attachment to intact collagen fibrils allows fibroblasts to achieve a spread architecture, through mechanical forces generated by the assembly of the cytoskeleton. In this state, the YAP/TAZ pathway is active, which maintains a youthful anabolic phenotype with net ECM production. In aged skin, fragmented collagen fibrils do not support fibroblast attachment, resulting in reduced mechanical force/stretching and a decline in YAP/TAZ function. In this state, fibroblasts display an aged catabolic phenotype, with net ECM degradation, which is self-perpetuating and creates a dermal microenvironment milieu that promotes the pathogenesis of many age- related skin diseases. We propose to investigate the hypothesis that the YAP/TAZ mechano-sensing signaling pathway in dermal fibroblasts is a critical regulator of age-related dermal ECM homeostasis. This data-driven hypothesis encompasses the key concept that dermal ECM homeostasis is governed by the adaptation of fibroblasts to the surrounding ECM microenvironment, rather than cell‐autonomous factors. Thus, we view dermal ECM homeostasis as involving “outside‐in adaptation” of dermal fibroblasts to the age‐related state of the dermal ECM, in which fibroblasts are embedded, and that this adaptation is critically regulated by YAP/TAZ. To test the above hypothesis, we have recently generated two complementary genetically modified mouse models: 1) conditional knockout of Yap/Taz in dermal fibroblasts, which results in striking impairment of both neonatal dermal ECM maturation and significantly accelerated chronological dermal ECM aging; 2) humanized mouse model of dermal aging driven by expression of collage-degrading matrix metalloproteinase-1 in dermal fibroblasts. Importantly, this model displays physiological inactivation of YAP/TAZ in response to ECM degradation. Following Specific aims are proposed to test the stated hypothesis: AIM 1: DETERMINE THE MOLECULAR MECHANISMS BY WHICH YAP/TAZ MEDIATES DERMAL ECM HOMEOSTASIS DURING EARLY POSTNATAL LIFE AND CHRONOLOGICAL AGING AIM 2: DETERMINE THE IMPACT OF RESTORATION OF YAP/TAZ FUNCTION ON DERMAL ECM HOMEOSTASIS AIM 3: INVESTIGATE MECHANISMS BY WHICH AGE-RELATED FUNCTIONAL DECLINE OF YAP/TAZ IS MEDIATED BY FIBROBLASTS “OUTSIDE-IN ADAPTION”