Molecular Pathobiology of Alport Syndrome

COL4A3， COL4A4和COL4A5基因的数百种变异导致了广泛的

Hundreds of variants in the COL4A3, COL4A4 and COL4A5 genes cause a broad range of glomerulopathies affecting the function of the glomerular basement membrane (GBM) in patients with Alport syndrome. These genes encode the assembly of collagen IV α345 scaffolds, the major constituent of the GBM. The pathogenic variants lead to a broad array of clinical manifestations, ranging from microscopic hematuria to end stage renal disease. The underlying mechanisms linking these variants with GBM abnormalities and renal failure remain obscure. Current therapy is limited to treatment with ACE inhibitors to slow progression and new therapies are in urgent need. How genetic variants of the α345 scaffold cause Alport syndrome remains unknown. Here, we focus on Z-variant causing Alport syndrome without loss of the α345 scaffold but rather reduction- or loss-of-function effect (hypomorph variant). We use this variant as a vanguard to decipher the function of the α345 collagen IV in GBM and develop new therapeutic approaches against Alport syndrome. In Aim 1, we will utilize new Z-variant animal models to understand mechanisms of α345 collagen IV function and dysfunction. In Aim 2, we will determine exact functional defects caused by Z-variant and similar pathogenic variants at protein and cellular levels to identify specific targets for small molecule therapies. In Aim 3, we will identify candidates for potential therapy by performing in vitro screening of natural and synthetic small molecules affecting assembly and stability of the collagen IV α345 scaffold. The completion of the Aims will advance our knowledge about Alport pathogenesis and lay out foundation for development of therapy against Alport syndrome.