Molecular Mechanisms of Mesangial Sclerosis

层粘连蛋白(LN)亚型在时间和空间上的表达对肾小球的发育和 在糖尿病肾病和其他进展性肾脏疾病中，有助于改变细胞功能。然而，几乎没有 了解调节LN亚型表达的机制。我们认为胰岛素样生长 因子结合蛋白-5(IGFBP-5)导致形成以丝胺为基础的核穿梭，它结合 转录因子(例如Sox9、GKLF、Sp1、Smad)和转录辅助激活因子(例如IGFBP-5和Lim 结构域蛋白(如FHL2)，并调节层粘连蛋白(LN)亚型在系膜细胞(MC)中的表达。这 假说提出了一种新的机制，即细胞-基质界面的扰动调节基因 表情。这一假设将通过以下方式进行检验： 具体目标1：描述丝胺核航天飞机的产生和组成如下 IGFBP-5对MC的治疗作用。首先，我们将演示细丝蛋白片段形成并移位到 原子核。第二，我们将确定被招募到复合体中的转录因子的特征； 最后，我们将评估转录共激活因子LIM结构域蛋白FHL2和IGFBP-5在 这个建筑群。 特定目标2：证明IGFBP-5介导的丝蛋白的核积累是必需的 LN基因表达的变化。首先，我们将演示IGFBP-5介导的丝素是必需的 对LN基因表达的影响。其次，我们将证明细丝穿梭被招募到LN基因座位上 在那里它特异性地干扰LN基因的转录。 具体目标3：确定丝胺核穿梭激活LN基因的机制 抄写。首先，我们将确定Fln是否与LN启动子直接相互作用，以及它是否驱动 抄写。其次，我们将定义航天飞机中转录控制所需的元件。 这些研究将确定以丝胺为基础的核航天飞机在调节IGFBP-5对 层粘连蛋白基因表达。了解LN亚型表达的转录控制将增加新的 层粘连蛋白在正常肾小球发生和肾小球紊乱中的作用 疾病。

Temporal and spatial expression of laminin (LN)isoforms is critical to glomerular development and contributes to altered cell function in diabetic nephropathy and other progressive renal diseases. Yet, little is known about the mechanisms that regulate LN isoform expression. We propose that insulin-like growth factor binding protein-5 (IGFBP-5) leads to formation of a filamin-based nuclear shuttle that binds transcription factors (e.g.sox9, GKLF, Sp1, Smad) and transcriptional co-activators (e.g., IGFBP-5 and LIM domain proteins such as FHL2) and regulates laminin (LN)isoform expression in mesangial cells (MC). This hypothesis suggests a novel mechanism whereby perturbations in the cell-matrix interface regulate gene expression. This hypothesis will be examined by: Specific Aim 1: To characterize the generation and composition of the filamin nuclear shuttle following treatment of MC with IGFBP-5. First, we will demonstrate that a fragment of filamin forms and translocates to the nucleus. Second, we will characterize the transcription factors that are recruited to the complex; and finally, we will evaluate the role of transcriptional co-activators, LIM domain protein FHL2 and IGFBP-5, in the complex. Specific Aim 2: To demonstrate that nuclear accumulation of filamin is required for IGFBP-5-mediated changes in LN gene expression. First, we will demonstrate that filamin is required for IGFBP-5-mediated effects on LN gene expression. Second, we will show that the filamin shuttle is recruited to LN gene loci where it specifically midifies LN gene transcription. Specific Aim 3: To define the mechanisms whereby the filamin nuclear shuttle activates LN gene transcription. First, we will determine if FLN interacts directly with the LN promoter and if it drives transcription. Second, we will define the elements in the shuttle that are required for transcriptional control. These studies will define the role of a filamin-based nuclear shuttle in mediating the effects of IGFBP-5 on laminin gene expresison. Understanding transcriptional control of LN isoform expression will add new insights into the role that LN plays in normal glomerulogenesis and that becomes disordered in glomerular disease.