Defining the role of cellular senescence in osteoarthritis

 描述（由申请人提供）：本项目的目标是更好地了解衰老和骨关节炎（OA）之间的联系。OA是一种疼痛的关节疾病，在美国估计有2700万人受到影响。虽然OA的风险随着年龄的增长而增加，但其原因尚不完全清楚。一个可能的解释是，软骨细胞，构成软骨组织的细胞，表现出一种与衰老相关的特殊形式的功能障碍，称为细胞衰老。衰老细胞的特征是不能分裂，过度产生炎症分子，并表达一种称为p16Ink4a的基因。该项目将探讨细胞衰老在关节发育过程中增加或与衰老或损伤相关的OA的假设，以及软骨细胞衰老在功能上有助于OA的发展。 科学的方法是利用经过基因工程改造的小鼠，使其具有不同的功能，以取代p16Ink4a的正常表达。第一个目标将通过分析表达荧光蛋白tdTomato而不是p16Ink4a的小鼠来跟踪单细胞水平的衰老发展。这将允许精确识别在OA发展过程中随着衰老和关节损伤后的衰老频率。此外，将基于tdTomato表达用流式细胞术分选细胞，并使用RNA测序将衰老细胞的转录谱与非衰老细胞进行比较。第二个目标将评估在成年期给予他莫昔芬后具有软骨细胞特异性p16Ink4a缺失的小鼠中OA的进展。因为预期这些小鼠表现出较少的软骨细胞衰老，所以在衰老或关节损伤的背景下OA减少的观察结果将支持维持衰老状态对OA的发展在功能上重要的假设。 这项工作的长期目标是确定预防或减缓OA进展的新策略，包括清除关节中的衰老细胞。该奖学金还将培训小鼠遗传学和软骨老化技术的主要研究者，以建立该领域的研究生涯。

 DESCRIPTION (provided by applicant): This goal of this project is to better understand the connection between aging and osteoarthritis (OA). OA is a painful disease of the joints that affects an estimated 27 million people in the United States. While it is well established that the risk for OA increases with age, the reason for this is not fully known. One potential explanation is that chondrocytes, the cells that make up cartilage tissue, exhibit a particular form of dysfunction associated with aging known as cellular senescence. Senescent cells are characterized by the inability to divide, the excessive production of inflammatory molecules, and the expression of a gene known as p16Ink4a. This project will explore the hypothesis that cellular senescence increases in joints during the development or OA associated with aging or injury, and that chondrocyte senescence functionally contributes to OA development. The scientific approach is to utilize mice that have been genetically engineered to have distinct functions in place of the normal expression of p16Ink4a. The first aim will track the development of senescence at the single cell level by analyzing mice that express the fluorescent protein tdTomato instead of p16Ink4a. This will allow precise identification of the frequency of senescence during the development of OA with aging and after joint injury. Furthermore, cells will be sorted with flow cytometry based on tdTomato expression and the transcriptional profile of senescent cells will be compared to non-senescent cells using RNA-sequencing. The second aim will assess the progression of OA in mice that have a chondrocyte-specific deletion of p16Ink4a upon administration of tamoxifen in adulthood. Because these mice are expected to exhibit less chondrocyte senescence, observations that OA is reduced in the context of aging or joint injury would support the hypothesis that maintaining a senescent state is functionally important to the development of OA. The long-term objective of this work is to identify new strategies for preventing or slowing the progression of OA, including the clearance of senescent cells from the joint. This fellowship grant will also train the principle investigator in technique of murine genetics and cartilage aging in order to establish a research career in the field.