MOLECULAR MECHANISMS IN HEREDITARY NEPHRITIS

Alport综合征是一种遗传性疾病，其特征是进行性 肾病，常与感觉神经性耳聋和 眼部异常。肾病与一种结构性疾病有关 肾小球基底膜(GBM)异常是由 编码α3、α4和α5链的基因突变 IV型胶原。最常见的形式是X-Linked，其中超过200 已在编码Alpha5链的Col4A5基因中发现突变。 这些突变干扰了 α3(IV)/α4(IV)/α5(IV)IV型超分子网络 胶原蛋白。大多数男性患者出生时肾功能接近正常， 随着时间的推移会恶化，从而导致终末期肾脏疾病 机制还不是很清楚。 这一提议的中心要旨是检验这样一个假设，即 X连锁遗传性肾炎进展为终末期肾病 由先天性肾小球基底膜畸形演变而来 (GBM)，涉及阻止发育开关的Col4A5突变 从不成熟的Alpha1(IV)/Alpha2(IV)网络到自然 Alpha3(IV)/Alpha4(IV)/Alpha5(IV)网络及其持久性 不成熟的网络使GBM易于蛋白质降解。这个 该研究计划的基石是使用犬类X连锁模型 COL4A5基因突变是一种过早终止的人类疾病 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机 正常犬肾脏中成熟的基底膜与患病雄犬的比较。 目的2：确定哪些肾小球细胞合成α3(IV)， α4(IV)链。 目的3：研究α3(IV)的表达与 α4(IV)和α5(IV)链。 目标4：确定消息和蛋白质的时间关系 正常人α1(IV)-α6(IV)链的表达水平 在疾病进展期间，将狗与受影响的公狗进行比较。 目的5：测定肾小球基底膜IV型胶原的易感性 正常和患病公犬的蛋白质分解降解。 这些目标的实现需要应用以下技术 分子生物学、生物化学、免疫化学和细胞生物学。它是 预期这些目标的实现将产生新的见解 Alport综合征的发病机制。一个 对这些机制的理解是发展 通过基因治疗或延迟治疗来纠正疾病的治疗措施 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.