MOLECULAR MECHANISMS IN HEREDITARY NEPHRITIS

Alport综合征是一种遗传性疾病，其特征在于进行性 肾病，常与感音神经性耳聋相关， 眼部异常肾病与结构性 肾小球基底膜（GBM）异常，由以下原因引起： 编码α 3、α 4和α 5链的基因中的突变 IV型胶原蛋白。最常见的形式是X-连锁，其中超过200 在编码α 5链的COL4A5基因中发现了突变。 这些突变干扰了 IV型α 3（IV）/α 4（IV）/α 5（IV）超分子网络 胶原大多数男性患者出生时肾功能接近正常， 其随着时间的推移恶化，导致终末期肾病， 不被理解的机制。 这一建议的中心思想是检验以下假设： X连锁遗传性肾炎进展为终末期肾病 从肾小球基底膜的先天性畸形演变而来 (GBM)它涉及COL4A5突变， 从不成熟的α 1（IV）/α 2（IV）网络到自然界 alpha3（IV）/alpha4（IV）/alpha5（IV）网络，以及这种网络的持久性。 不成熟的网络使GBM易于蛋白水解降解。的 研究计划的基石是使用犬X连锁模型， COL4A5基因突变是过早停止的人类疾病 密码子具体目标是： 目标1：确定从不成熟到成熟的转变的性质和时间 正常犬肾脏中的成熟GBM与受累雄性犬相比。 目的2：确定哪些肾小球细胞合成α 3（IV）， α 4（IV）链。 目的3：检查α 3（IV）的表达之间的关系， α 4（IV）和α 5（IV）链。 目的4：确定信息和蛋白质的时间关系 正常人中α 1（IV）-α 6（IV）链的表达水平 在疾病进展期间，将受影响的雄性犬与受影响的雄性犬进行比较。 目的5：确定GBM的IV型胶原对 正常和受累雄性犬的蛋白水解降解。 要实现这些目标，就需要应用以下技术： 分子生物学、生物化学、免疫化学和细胞生物学。是 预计目标的实现将产生新的见解， Alport综合征的发病机制。一个 了解这些机制是发展的基础 通过基因治疗来纠正疾病的治疗措施或延迟 进展为终末期肾病。

Alport Syndrome is a hereditary disorder characterized by progressive nephropathy which is frequently associated with sensorineural deafness and ocular abnormalities. The nephropathy has been linked to a structural abnormality in the glomerular basement membrane (GBM) which is caused by mutations in the gene encoding the alpha3, alpha4 and alpha 5 chains of type IV collagen. The most common form is X-linked, in which over 200 mutations have been found in the COL4A5 gene encoding the alpha5 chain. These mutations interfere with the formation of the alpha3(IV)/alpha4(IV)/alpha5(IV) supramolecular network of type IV collagen. Most male patients have near normal kidney function at birth, which deteriorates over time leading to end-stage renal disease by mechanisms that are not understood. The central thrust of this proposal is to test the hypothesis that the progression to end-stage renal disease in X -linked hereditary nephritis evolves from a congenital malformation of the glomerular basement membrane (GBM) which involves COL4A5 mutations that arrest a developmental switch from the immature alpha1(IV)/alpha2(IV) network to the nature alpha3(IV)/alpha4(IV)/alpha5(IV) network, and the persistence of this immature network predisposes the GBM to proteolytic degradation. The cornerstone of the research plan is a use of the canine X-linked model of the human disease in which the COL4A5 gene mutation is a premature stop codon. The specific aims are: Aim 1: Determine the nature and timing of the switch from immature to mature GBM in normal dog kidney in comparison to affected male dogs. Aim 2: Determine which glomerular cells synthesize the alpha3(IV), alpha4(IV) chains. Aim 3: Examine the relationship between the expression of the alpha3(IV), alpha4(IV) and alpha5(IV) chains. Aim 4: Determine the temporal relationship at both the message nd protein levels of the expression of the alpha1(IV)-alpha6(IV) chains in normal dogs compared to affected male dogs during progression of their disease. Aim 5: Determine the susceptibility of type IV collage of GBM to proteolytic degradation in normal and affected male dogs. The achievement of these aims requires application of the techniques of molecular biology, biochemistry, immunochemistry and cell biology. It is anticipated that the achievement of the aims will yield new insights into the mechanisms underlying the pathogenesis of Alport Syndrome. An understanding of these mechanisms is fundamental to the development of therapeutic measures to correct the disorder by gene therapy or to delay progression to end stage renal disease.