Melissa Little Group (GUDMAP1)
Congenital anomalies of the urogenital tract (UGT) represent the third most frequent of all birth defects, occurring in approximately 26-30/10,000 live births. Only heart and limb defects are more prevalent. Such defects can vary from severe (persistent cloaca, cystic kidney disease, hydronephrosis, diphallia) to more moderate (hypospadias, streak gonads, horseshoe kidney, micropenis, crytorchidism, unliateral renal agenesis). Some cancers of the urogenital tract (gonadoblastoma, Wilms' tumour) represent a persistence of the embryonic state. In addition, adult onset renal disease and other disorders of the UGT show reactivation of molecules key to the normal development of the UGT. Indeed, there is now evidence that the number of nephrons endowed before birth in your kidneys can affect whether or not you will present with chronic renal disease later in life. All these observations highlight the need to comprehensively understand the molecular basis of UGT development. The starting point for this understanding is the temporal and spatial analysis of all genes expressed during UGT development.
Our approach is to collect such information as high-throughput RNA in situ hybridization data amassed in a visual atlas. The genes selected are based on our previous analyses of UGT gene expression using microarray-based expression profiling. This approach will enable us to record the expression pattern of a gene over time in all parts of the urogenital tract. At early timepoints (E9.5, 10.5, 11.5, 12.5), we are looking at the gene expression pattern in whole developing organs and in organ cultures of the kidney (wholemount ISH). At later developmental timepoints (E15.5), and in the adult mouse tissue, we are performing high-resolution section ISH coupled with antibody immunohostochemistry. By using known antibodies to specific subcompartments and cell types within the kidney, we can give a more accurate description of the cell types / compartments in which a gene is being expressed. We are making all this visual data available at high resolution annotated using the standardized descriptive anatomical terms for the developing urogenital tract developed by the GUDMAP group. Our objective is to analyse around 5000 genes, some at as many as 7 timepoints, in early urogenital tract, early kidney organ culture, and in midgestational and adult kidney, ureter, bladder, ovary and testis. The genes which we will analyse will come from our own microarray-based expression profiling of kidney development over time and within subcompartments (dynamic and spatially-restricted), or meta-analysis of other datasets, including the RIKEN data on kidney expression and microarray-based expression profiling of normal kidney or renal disease.
Relationship to the Overall Goals of GUDMAP
The overall goal of GUMDAP is to chronicle the expression of genes, both temporally and spatially, during the development and maturation of the urogenital tract and to create tools for the scientific community to examine the biological function of these genes. The creation of such an atlas of gene expression will serve as a reference point in studies interested in the analysis of lineage, cell fate and disease within this organ system. Our contribution to these overall goals will be to validate laser capture and microarray expression profiling data, both of our own and of the group as a whole, at the spatial level and to provide a visial interpretation of that expression pattern across the entire urogenital tract across time.