MOLECULAR MECHANISMS OF RENAL INJURY

基底膜由IV型胶原、层粘连蛋白、 蛋白多糖和牙本质蛋白。IV型胶原由一个六口之家组成 不同的阿尔法链。肾小球基底膜(GBM)胶原蛋白， 例如，由α-3(IV)和α-5(IV)两个阶段形成 胶原蛋白出现的时间较晚，并最终在一开始主导了原癌 由α-1(IV)和α-2(IV)链形成。基底膜 相反，来自肝脏的基因通常不表达α-5(IV)或 α-6(IV)胶原蛋白在最初形成后形成。 这种从胎儿α-1(IV)和α-2(IV)胶原到α-1(IV)胶原蛋白的转变 人GBM中的3(IV)、α-4(IV)和α-5(IV)链是一种 发展事件，推动了毛细管环的制造 肾小球。我们相信，这种发育转换提高了 通过保护性地增强毛细管过滤器的结构完整性 肾小球滤过部位对局部蛋白水解酶的抵抗力。这 X连锁Alport患者的大多数肾脏开关有缺陷 有α-5(IV)基因突变的综合征(XAS)并继续 肾功能衰竭。 我们建议通过以下方法来研究这种发育转换的机制 研究α-5(IV)胶原基因的超分子调控。 我们假设开关是通过打开染色质来控制的 选定的组织，并处于DNA结合的模块控制下 蛋白质。确定这些轨迹控制区(LCR)的坐标 是理解该监管的更大方面的第一步 进程。 对IV型胶原的转换至关重要的调控区域将 通过定位肾脏中独特的DNasel超敏部位进行研究 染色质位于人类α-5(IV)基因的起始处。我们有 从该区域获得了一个含有基因组DNA的BAC克隆 染色体Xq22.2，并开发了一种测量策略 人α-5(IV)在转基因小鼠中的转录本。侯选人 过敏性部位将以转基因的形式表达并进行评估 功能活动、转换、位置独立性和拷贝数- 依赖。然后，被识别为LCR的过敏性部位可以 在核小体水平上的探索，随后的，二级的 学习。

Basement membranes are composed of type IV collagen, laminins, proteoglycans and entactin. Type IV collagen comprises a family of six different alpha-chains. Glomerular basement membrane (GBM) collagen, for example, is formed in two phases with alpha-3(IV), and alpha-5(IV) collagens appearing later and eventually dominating protomers initially formed from alpha-1 (IV) and alpha-2(IV) chains. Basement membranes from liver, in contradistinction, do not normally express alpha-5(IV) or alpha-6(IV) collagens after their initial formation. This switch from fetal alpha-1 (IV) and alpha-2(IV) collagens to alpha- 3(IV), alpha-4(IV), and alpha-5(IV) chains in human GBM is a developmental event that advances the fabrication of capillary loops in the glomerulus. We believe this developmental switch improves the structural integrity of the capillary filter by protectively enhancing its resistance to local proteases at the site of glomerular filtration. This switch is defective in most kidneys from patients with x-linked Alport Syndrome (XAS) who have mutations in the alpha-5(IV) gene and go on to renal failure. We propose to examine the mechanism of this developmental switch by studying the supramolecular control of the alpha-5(IV) collagen gene. We hypothesize that switching is gated by the opening of chromatin in selected tissues, and is under the modular control of DNA-binding proteins. Determining coordinates for these locus control regions (LCRs) is the first step in understanding the larger aspects of this regulatory process. Regulatory regions important for the switching of type IV collagen will be studied by mapping unique DNasel hypersensitive sites in kidney chromatin remote to the start of the human alpha-5(IV) gene. We have obtained a BAC clone containing genomic DNA from this region on chromosome Xq22.2, and have developed a strategy for measuring human alpha-5(IV) transcripts in transgenic mice. Candidate hypersensitive sites will be expressed as transgenes and evaluated for functional activity, switching, position-independence and copy number- dependence. Hypersensitive sites identified as LCRs can then e explored at the level of the nucleosome in subsequent, second-order studies.