REGULATION OF MESANGIAL CELL ACTIVATION BY GLOMERULAR MICROENVIRONMENT

活化的系膜细胞在急性肾小球肾炎和慢性肾小球肾炎中起重要作用。 炎症和慢性纤维化过程， 肾小球硬化系膜细胞（MC）培养不完全模型， 活化的表型，并且不良地反映正常的原位表型。我们 建议分析慢性肾衰竭易感动物和培养 MC的细胞外基质（ECM），这更好地模拟在体内 条件，将确定控制MC的监管流程 活化，一个以肌成纤维细胞转化为特征的过程。 初步数据表明：（1）系膜细胞肌成纤维细胞 体内分化代表对ECM的适应性反应 （2）损伤诱导的ECM变化调节功能性细胞外基质（ECM）， MC对促炎信号的反应;（3）ECM基底膜上 凝胶，MC迁移到多细胞网络和发展细胞间 连接复合体，类似于正常肾小球中的MC;（4）I型 胶原凝胶，MC缺乏这些细胞间连接，类似于MC中的 病变肾小球;（5）MC在簇中的组装受到以下因素的调节： 酪氨酸激酶和磷酸酶系统;和（6）这种空间模式 与Eph家族酪氨酸激酶的连接和激活相关 受体在体外和正常ES+，但不是CRF倾向的ES+小鼠。 我们假设，在正常的系膜中，ECM调节的优势 细胞-细胞接触，这部分是由EPH家族的受体介导的 酪氨酸激酶，维持正常（静止）系膜细胞表型。 在受损的肾小球内，随着ECM丰度和组成的变化， 发生细胞-细胞接触和Eph受体激酶活性的丧失， 允许无对抗性的系膜细胞-基质相互作用和系膜 肌成纤维细胞分化（激活）。三个具体目标是 提出：（1）MC肌成纤维细胞分化是否代表了一种适应性分化？ 对损伤诱导的ECM环境变化的反应 进行性CRF？(2)ECM如何引导MC组装成网络 通过连接复合体连接起来什么是分子组成的 体外和体内的MC连接？and（3）MC EPH家族酪氨酸 B61配体激酶受体在细胞-细胞位点浓缩 收缩并保持静止的MC表型？这一近期目标 这项提议是要鉴定出调节 从正常到活化MC表型转变。了解这些 这些变化应允许开发合理的治疗方法，以抑制或 改善持续的肾小球炎症和瘢痕形成。

The activated mesangial cell is critically involved in both the acute inflammatory and chronic fibrosing processes that culminate in glomerulosclerosis Mesangial cells (MC) in culture incompletely model an activated phenotype, and poorly reflect a normal in situ phenotype. We propose that analysis of chronic renal failure-prone animals and culture of MC on extracellular matrices (ECM), which better mimics in vivo conditions, will identify the regulatory processes that control MC activation, a process characterized by myofibroblast conversion. Preliminary data demonstrate that: (1) mesangial cell myofibroblast differentiation in vivo represents an adaptive response to the ECM environment; (2)injury-induced changes in ECM regulate the functional response of MC to pro-inflammatory signals; (3) on ECM basement membrane gels, MC migrate into multi-cellular networks and develop intercellular junctional complexes, similar to MC in normal glomeruli; (4) on Type I collagen gels, MC lack these intercellular junctions, similar to MC in diseased glomeruli; (5) assembly of MC in clusters is regulated by tyrosine kinase and phosphatase systems; and (6) this spatial patterning correlates with ligation and activation of Eph family tyrosine kinase receptors both in vitro and in normal ES+ but not the CRF-prone Es+mice. We hypothesize that, in the normal mesangium, an ECM-regulated dominance of cell-cell contacts, which is mediated in part by EPH family of receptor tyrosine kinases, maintains a normal (quiescent) mesangial cell phenotype. Within the injured glomerulus as ECM abundance and composition change, loss of cell-cell contacts and Eph receptor kinase activity occurs, permitting unopposed mesangial cell-matrix interaction and mesangial myofibroblast differentiation (activation). Three specific aims are proposed: (1) Does MC myofibroblast differentiation represent an adaptive response to injury induced changes in ECM environment in animal models of progressive CRF?; (2) How does ECM direct the assembly of MC into networks linked by junctional complexes? What are the molecular components of the MC junctions in vitro and in vivo?" and (3) Does a MC EPH family tyrosine kinase receptor for the B61 ligand concentrate at site of cell-cell contracts and maintain a quiescent MC phenotype? The immediate goal of this proposal is to identify candidate molecules that regulate the transition from a normal to an activate MC phenotype. Understanding these changes should allow development of rational therapies to inhibit or ameliorate ongoing glomerular inflammation and scarring.