Translational Control in Cartilage Biology. - Resubmission - 1

描述（由申请人提供）：该提案侧重于软骨生物学中的翻译控制。软骨细胞是负责骨骼和软骨组织生长和维持的主要细胞。软骨细胞稳态失调引起各种肌肉骨骼疾病，包括骨关节炎（OA）。虽然许多研究都集中在参与调节软骨细胞增殖和分化的转录机制，翻译控制在这些过程中的作用从来没有得到解决。是 众所周知，软骨细胞的增殖和分化受许多信号分子的调节，并且在这些过程中的中心作用之一属于成纤维细胞生长因子（FGF）。虽然在大多数细胞类型中，FGF诱导增殖并保护免于凋亡，但增殖的软骨细胞在其对FGF的响应方面是不同的，其响应为生长抑制。根据我们的初步数据，蛋白质合成显着降低FGF处理的软骨细胞，反应是相反的，在许多其他系统中的生长因子的蛋白质合成的良好建立的刺激。此外，我们能够检测FGF诱导的真核起始因子4 E结合蛋白（4 E-BP）的活化，4 E-BP是已知的帽依赖性翻译抑制剂。虽然4 E-BP在人关节软骨细胞中也有活性，但其活性在OA软骨中显著较低，表明在这种病理条件下翻译装置失调。本研究旨在探讨FGF诱导的增殖软骨细胞蛋白质合成下调和软骨细胞分化过程中蛋白质合成调控的机制。 在本申请的第一部分中，我们将研究FGF诱导的增殖软骨细胞蛋白质合成的抑制。我们将确定导致这种多样化反应的机制。我们的第二部分的建议将旨在确定特定池的mRNA，积极翻译下的蛋白质合成的一般抑制。我们将采用核糖体分析来鉴定这些mRNA。该提案的最后一部分旨在确定与正常人体软骨相比，OA软骨中导致翻译机制激活的机制。该项目将为促进OA和其他肌肉骨骼疾病的新的特异性靶点提供基础。

DESCRIPTION (provided by applicant): This proposal is focused on translation control in cartilage biology. Chondrocytes are the primary cells responsible for the growth and maintenance of bones and cartilage tissue. Deregulation of chondrocyte homeostasis gives rise to a variety of musculoskeletal disorders, including osteoarthritis (OA). While many studies have focused on transcriptional mechanisms involved in regulation of chondrocytes proliferation and differentiation, the role of translation control in these processes has never been addressed. It is well established, that chondrocytes proliferation and differentiation are regulated by a number of signaling molecules and one of the central roles in these processes belongs to Fibroblast Growth Factors (FGFs). While in most cell types FGFs induce proliferation and protect from apoptosis, proliferating chondrocytes are distinct in their response to FGF, responding with growth inhibition. According to our preliminary data, protein synthesis is dramatically decreased in FGF-treated chondrocytes, a response that is opposite to well established stimulation of protein synthesis by growth factors in many other systems. Moreover, we were able to detect FGF-induced activation of eukaryotic Initiation Factor 4E Binding Protein (4E-BP) which is a known inhibitor of cap-dependent translation. While 4E-BP was also active in human articular chondrocytes, its activity was significantly lower in OA cartilage, indicating deregulation of translational apparatus under this pathological condition. This proposal aims to investigate the mechanism that mediates FGF-induced downregulation of protein synthesis in proliferating chondrocytes and regulation of protein synthesis during differentiation of chondrocytes. In the first part of this application we will investigate FGF-induced inhibition of protein synthesis in proliferative chondrocytes. We will determine the mechanism leading to this diverse response. The second part of our proposal will aim to identify specific pools of mRNAs that are actively translated under general repression of protein synthesis. We will employ ribosomal profiling to identify these mRNAs. The last part of the proposal will aim to determine the mechanism leading to activation of translation machinery in OA cartilage when compared to normal human cartilage. This project will provide basis for facilitating new specific targets in OA and other musculoskeletal disorders.