Discussion

The architectural design of our kidneys is amazingly complex, and culminates in the 3D structure of the glomerular filter. During filtration, plasma passes through a sieve consisting of a fenestrated endothelium and a broad basement membrane before it reaches the most unique part, the slit diaphragm, a specialized type of intercellular junction that connects neighbouring podocyte foot processes. When podocytes become stressed, irrespective of the causative stimulus, they undergo foot process effacement and loss of slit diaphragms--two key steps leading to proteinuria. Thus, proteinuria is the unifying denominator of a broad spectrum of kidney diseases. With the rising prevalence of chronic kidney disease and the fact that glomerular diseases account for the majority of patients with end-stage renal disease, further investigation and elucidation of this unique structure is of paramount importance. Our team has been using complementary methods including high resolution ultrastructural imaging, drosophila models, C. elegans models and transgenic mice to elucidate the structure and function of the SD. The observations might help to introduce novel concepts in podocyte biology, which could pave the way to development of highly desired, specific therapeutic strategies for glomerular diseases.