THE ROLE OF BAG-1 IN CHONDROCYTE AGING AND DISEASE

描述（由申请人提供）：软骨和软骨细胞随着年龄的增长而发生变化，包括细胞凋亡增加和对生长因子的反应下降。年龄相关的变化发生在几个关节，包括颞下颌关节以及膝关节和髋关节，并可能使软骨易患退行性关节疾病（骨关节炎，OA）。这些变化的分子基础尚不明确。Bag- 1（Bcl-2 athanogene-1）是与Bcl-2、热休克蛋白、生长因子受体、类固醇激素受体和激酶相互作用的蛋白家族成员。Bag-1在细胞凋亡、增殖和对生长因子的反应等细胞活动中起着关键的调节作用。本文研究的总体假设是Bag-1蛋白是软骨细胞功能的重要调节因子，Bag-1表达随年龄的变化导致了组织的变化。具体目的是设计综合实验，直接建立软骨老化和年龄相关软骨疾病期间Bag-1蛋白的表达模式，并确定在稳态和应激条件下软骨细胞中Bag-1调节的精确途径。目的1：利用衰老模型（衰老小鼠、衰老大鼠、衰老加速小鼠）和与人类OA疾病严重程度的关系，确定Bag-1在关节软骨中的表达模式。此外，我们还验证了Bag-1表达随衰老（或疾病）而下降与内质网（ER）应激增加有关的特定子假设。目的2：确定Bag-1在稳态和应激条件下调控软骨细胞凋亡和基质蛋白表达的确切机制。基本的方法将是直接调节软骨细胞中的Bag-1水平，通过过度表达和敲低的方式，有或没有诱导内质网应激。这些目标的成功完成将为Bag-1在软骨细胞生物学中的作用提供信息。此外，这些研究将有助于确定在软骨老化和疾病过程中操作的潜在的新分子机制。最后，假设驱动的研究计划与重点学生参与的结合将为学生实习生提供强有力的培训组成部分。与年龄相关的软骨变化会导致骨关节炎，而骨关节炎是导致老年人疼痛和痛苦的主要原因之一。通过确定软骨在衰老过程中发生的具体变化，将有可能确定减缓或停止这一过程的具体策略，并减少软骨疾病对社会的影响。

DESCRIPTION (provided by applicant): Cartilage and chondrocytes undergo changes with aging including increased apoptosis and decreased response to growth factors. Age-associated changes occur in several joints including the temporomandibular joint as well as knee and hip and may predispose the cartilage to degenerative joint disease (osteoarthritis, OA). The molecular basis for these changes is not well-defined. Bag- 1(Bcl-2 athanogene-1) is a member of a protein family that interacts with Bcl-2 as well as heat shock proteins, growth factor receptors and steroid hormone receptors, and kinases. Bag-1 plays a key regulatory role in cellular activities such as apoptosis, proliferation, and response to growth factors. The overall hypothesis under study herein is that the Bag-1 protein is an important regulator of chondrocyte function and that changes in Bag-1 expression with age contribute to the tissue changes. The specific aims are integrated experiments designed to directly establish the Bag-1 protein expression pattern during cartilage aging and during age-associated cartilage disease and to define the precise pathways regulated by Bag-1 in chondrocytes under homestatic and stress conditions. Aim 1: Define the expression pattern of Bag-1 in articular cartilage using models of aging (aging mice, aging rats, senescence accelerated mice) and in relation to disease severity in human OA. Also, test the specific subhypothesis that the decline in Bag-1 expression with aging (or disease) is associated with increased endoplasmic reticulum (ER) stress. Aim 2: Identify the precise mechanisms by which Bag-1 regulates chondrocyte apoptosis and matrix protein expression under homeostatic and stress conditions. The basic approach will be to directly modulate Bag-1 levels in chondrocytes by over- expression and knockdown approaches with and without the induction of ER stress. The successful completion of these aims will provide information about the role of Bag-1 in chondrocyte biology. In addition these studies will help define a potentially novel molecular mechanism operating during cartilage aging and disease. Finally, the combination of the hypothesis-driven research plan with focused student involvement will provide a strong training component for the student trainees. of Proposed Research to Public Health Age-associated changes in cartilage lead to osteoarthritis which is one of the major causes of pain and suffering among our aging population. By identifying the specific changes that occur in cartilage during aging it will be possible to identify specific strategies to slow down or stop this process and reduce the impact of cartilage disease on society.