Alport disease in humans which usually results in proteinuria and kidney

Alport disease in humans which usually results in proteinuria and kidney failure is caused by mutations to the genes and absence of collagen α3α4α5(IV) networks found in mature kidney glomerular basement membrane (GBM). with trypsin and Aurora A Inhibitor I prepared for mass spectrometry peptide ion mapping/fingerprinting and protein identification through database searching. The intermediate filament protein vimentin was upregulated ~2.5 fold in Alport glomeruli compared to wild-type. Upregulation was confirmed by quantitative real time RT-PCR of isolated Alport glomeruli (5.4 fold over wild-type) and quantitative Aurora A Inhibitor I confocal immunofluorescence microscopy localized over-expressed vimentin specifically to Alport podocytes. We next hypothesized that increases in vimentin large quantity might Aurora A Inhibitor I impact the basement membrane protein receptors integrins and screened Alport and wild-type glomeruli for expression of integrins likely to be the main receptors for GBM type IV collagen and laminin. Quantitative immunofluorescence showed an increase in integrin α1 expression in Alport mesangial cells and an increase in integrin α3 in Alport podocytes. We conclude that overexpression of mesangial integrin α1 and podocyte vimentin and integrin α3 may be important features of glomerular Alport disease possibly affecting cell-signaling cell shape and cellular adhesion to the GBM. Introduction The kidney glomerulus is usually a unique semipermeable capillary tuft that allows the passage of plasma water and small solutes into the tubular portion of the nephron while retaining albumin and larger molecules in the blood circulation. Diseases affecting the glomerular barrier properties commonly result in the loss of circulating plasma proteins into the urine a condition called Aurora A Inhibitor I proteinuria and unchecked proteinuria Rabbit polyclonal to IL22. can Aurora A Inhibitor I lead to end stage renal disease requiring dialysis and/or kidney transplantation. The filtration barrier itself is comprised of the fenestrated glomerular endothelium with its glycocalyx and loosely attached cell coat [1] the glomerular basement membrane (GBM) and the visceral epithelial podocytes with their intervening slit diaphragm complexes [2]. The endothelium GBM and podocytes are all necessary and work synergistically in maintaining the glomerular filtration barrier. The importance of the GBM for glomerular barrier properties in humans is underscored by Alport disease. Affected individuals harbor mutations to any one of the three genes encoding the type IV collagen network found in mature GBM; locus [8] [9]. Without the collagen α3(IV) chain a stable α3α4α5(IV) heterotrimer can not form and GBMs lack this collagen IV isoform altogether. Although disease severity differs depending upon strain [10] both of the genetic mouse models parallel key aspects of human Alport kidney disease progression. Specifically null mice are viable and kidney function appears normal until the onset of proteinuria at ~5 weeks of age. Like Alport patients mouse mutants retain collagen α1α2α1(IV) in their GBMs into adulthood and there is also ectopic expression laminins α1 α2 and β1 in peripheral loop GBM [11] [12] especially in the irregular subepithelial thickenings that are typical of Alport glomeruli [13]. Whereas the collagen α1α2α1(IV) seen in immature GBM as well as the ectopic laminins of Alport mouse GBM originate from both endothelial cells and podocytes the podocyte alone is responsible for the synthesis of collagen α3α4α5(IV) found in mature GBM [14]. The progression of Alport syndrome in humans and in mouse models ultimately leads to end stage renal disease but Aurora A Inhibitor I this is a relatively slow process compared to other podocyte mutations. For example mutations affecting (encoding the slit diaphragm protein nephrin) or (encoding the slit diaphragm-associated protein podocin) result in renal failure and death within a few days after birth [15] [16]. Although the α1α2α1(IV) collagen retained in Alport GBMs is apparently able to compensate partially for the absence of α3α4α5(IV) collagen the later isoform has more cysteine residues available for disulfide crosslinks between α chains which may confer improved resistance of the GBM to hydrostatic pressure within the glomerular capillary [17]. Alport GBM has also been shown to be more susceptible to proteolysis knockout mice and three age-matched wild-type controls. Three samples were prepared consisting of equal.