The objective is to study and resolve the riddles of certain diseases in childhood, specifically those associated with abnormalities of the glomerular capillary filter. The grant focuses on research that will help us understand the pathogenesis of familial forms of renal disease including Alport-type familial nephritis, nephrotic syndrome, and glomerulonephritis. This proposal is predicated on observations that an antigenic determinant(s) on the non-collagenous domain (NC1) of type IV collagen is not detected on the glomerular basement (GBM) membrane and epidermal basement membrane (EBM) of males with Alport-type familial nephritis whereas in affected females the EBM shows zones of reactivity separated by gaps of non-reactivity, supporting X-linked dominant inheritance. Direct analysis of Alport kidney basement membrane by PAGE and 2-dimensional gel analysis demonstrates absence of a normally-occurring 28 kDa antigenic component. Studies include further antigenic analysis of affected kindreds; development of highly specific and informative monoclonal antibodies; detailed analyses of NC1 monomers and dimers; and development of cDNA probes to the NC1 component. The proposal is concerned with components of the human glomerular visceral epithelium and basement membrane. We will characterize the role of a previously unrecognized component of human GBM - MBM15 antigen - which appears early in ontogeny, is a component of epithelial spikes in membranous nephropathy; is synthesized by human glomerular epithelial cells in culture, and is a normal urinary constituent. Studies will be carried out on human glomerular polyanion (GPA) (podocalyxin), a negatively-charged sialoprotein that covers the surface of viscerel eplithelial cells, and proteoglycan located in the lamina rara of the GBM--in order to define further their role in human disease. We have shown that human glomerular epithelium in culture synthesize a variety of components including proteoglycans, MBM15 antigen, collagen IV, laminin, fibronectin, and certain lymphohemopoietic antigens. The role of the epithelial cell in modulating and controlling components of the glomerular capillary will be addressed. The methods used include cell culture, immunohistochemistry, morphology, biochemistry, immunology, and cDNA technology.
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