Genomic and proteomic dissection of the molecular basis of kidney development.

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The number of nephrons present in the human adult kidney can vary by threefold. This is likely to be due to slight variations in the rate of nephron formation during development. Evidence is mounting that a reduced number of nephrons can predispose to renal failure later in life in response to stresses such as hypertension or substance abuse. 80,000 new cases of end stage renal failure occur each year in the US, with 25% of these related to hypertension and therefore possibly linked to a low nephron number. While it is known that the kidney arises through a series of reciprocal inductive events between the metanephric mesenchyme and the ureteric bud, a better understanding of the molecular basis of these events is needed to understand what dictates nephron endowment. The Wilms tumour suppressor protein WT1 is not only mutated in some cases of the childhood kidney cancer, Wilms tumour, but is also critical for the normal development of the metanephros, as demonstrated by knockout experiments in mice. One of the earliest genes expressed in the metanephric mesenchyme, WT1 is thought to prevent this tissue from dying before differentiation, directing it to form the kidney and, postnatally, regulating normal podocyte function. Although known to be a nuclear regulatory protein, the genes directly regulated by WT1 have not been clearly or convincingly delineated. This study aims to directly screen for changes to gene expression and protein production levels induced by WT1. To do so, an array approach unique in its use of a specific array set derived from developing kidney will be used. In concert, additional specific clone sets derived from mouse kidney prior and post the commencement of nephron formation will be constructed and analysed. As WT1 is a nuclear protein involved in splicing, this study will involve a parallel investigation at a proteomic level of changes in spliceosomal proteins in response to changes in WT1.