Translational Control in Cartilage Biology

项目摘要 软骨细胞是软骨的主要细胞，负责大部分软骨细胞的形成和生长。 骨骼，特别是长骨和软骨组织。软骨的形成和重塑需要 细胞外基质蛋白的有效合成和基质降解蛋白的同等有效表达 内切酶不平衡的软骨细胞稳态导致各种肌肉骨骼疾病从软骨 骨关节炎（OA）中关节的变性导致生长板中软骨细胞增殖不足， 软骨发育不全我们最近的工作表明，mRNA翻译的调节在细胞凋亡中起着至关重要的作用。 软骨细胞的稳态，因为我们证明了4 E-BP（真核起始因子（eIF）4 E 结合蛋白，帽依赖性翻译的阻遏物）在FGF诱导的增殖细胞生长停滞中的作用 软骨细胞以及维持健康的关节软骨。通过与关键的翻译起始结合， 因子eIF 4 E，其是识别真核生物mRNA的帽结构和组装多个 称为eIF 4F的亚基复合物，募集40 S核糖体，4 E-BP功能抑制选择的翻译。 eIF 4F依赖的加帽mRNA。在本申请的第一部分中，我们将阐明 在软骨细胞中FGF诱导的4 E-BP活化。为了进一步了解复杂的转录后基因 我们计划确定Patl 1（蛋白质PAT 1同源物1）- a在软骨细胞中FGF信号传导的控制中的作用， 蛋白质参与mRNA的稳定性。我们在磷酸化蛋白质组学分析中鉴定出这种蛋白质为FGF 响应性的并且是介导FGF抑制反应所必需的。我们将研究 在软骨细胞分化过程中控制翻译控制，重点是骨- 脂肪和软骨生成。在我们应用软骨细胞的最后一部分，我们将研究如何 eIF 4F的异常调节影响OA软骨的整体mRNA翻译谱，并研究 eIF 4F活性可以在体外和体内逆转OA样表型。

PROJECT SUMMARY Chondrocytes are the cartilage primary cells responsible for the pattering and growth of much of the skeleton, particularly the long bones and cartilage tissue. Formation and remodeling of cartilage requires efficient synthesis of extracellular matrix proteins and equally efficient expression of matrix-degrading enzymes. Imbalanced chondrocyte homeostasis leads to a variety of musculoskeletal disorders from cartilage degeneration in the joint in osteoarthritis (OA) to inadequate chondrocyte proliferation in the growth plate in achondroplasia. Our recent work revealed that regulation of mRNA translation plays a crucial role in chondrocyte homeostasis, as we demonstrated the importance of 4E-BP (eukaryotic initiation factor (eIF) 4E Binding Protein, a repressor of cap-dependent translation) in FGF-induced growth arrest in proliferating chondrocytes as well as in sustaining healthy articular cartilage. By binding to the critical translation initiation factor eIF4E, which is required to recognize the cap structure of eukaryotic mRNA and assemble a multi- subunit complex called eIF4F that recruits the 40S ribosome, 4E-BP functions to repress translation of select capped mRNAs that are eIF4F-dependent. In the first part of this application we will elucidate the mechanism of FGF-induced 4E-BP activation in chondrocytes. To understand further the complex post-transcriptional gene control upon FGF signaling in chondrocytes we plan to determine a role of Patl1 (Protein PAT1 homolog 1) – a protein involved in mRNA stability. We identified this protein in our phosphoproteomics analysis as FGF responsive and necessary for mediating FGF inhibitory response. We will investigate the mechanisms that govern translation control during chondrocyte differentiation focusing on the proper balance between osteo- adipo- and chondrogenesis. In the last part of our application chondrocytes we will investigate how dysregylation of eIF4F impacts global mRNA translation profile of OA cartilage and investigate if modulation of the eIF4F activity can reverse OA like phenotype in vitro and in vivo.