| Summary |
Glomerular podocytes are highly differentiated kidney cells that constitute one of the key components responsible for removing toxins and metabolic waste while preserving nutrients in the bloodstream in the renal glomerulus. In addition, podocytes contribute significantly to the formation of the glomerular basement membrane and the integrity of the vascular endothelium. Thus, podocyte injury and/or loss of podocytes results in impaired blood filtration and causes many common renal diseases characterized by severe proteinuria (protein in the urine) and hypoalbuminemia (low levels of blood albumin). Small lipopholic molecules such as steroids, fatty acids, prostaglandins and vitamin metabolites control many aspects of animal development, cell proliferation and differentiation, and homeostasis through binding to their intracellular receptors. Upon binding to their cognate ligands, these nuclear receptors (NRs) are capable of turning on or off of an array of gene networks. By doing so, they regulate a whole spectrum of cellular activities. The ability of small molecule hormones to regulate NR activity makes them excellent pharmaceutical targets. Clinical evidence and animal studies have implicated several NRs in contributing to podocyte development and disease. Recent studies from animals and cultured human or mouse podocytes indicate that synthetic hormones including estradiol, glucocorticoid, retinoid, pioglitazone, vitamin D3 and WY-14643 protect or rescue podocytes from experimental injury. Post treatment of injured podocytes with ligands for the above-mentioned NRs restores cytoskeletal architecture of the podocytes. Nonetheless, the mechanisms underlying the ability of these hormones in protecting podocytes remain largely unexplored. This is partly due to our limited knowledge of the target genes controlled by these hormones. In order to elucidate the mechanisms by which Dex, VD3 and ATRA elicit their renoprotective activity, we initiate a gene expression profiling study to identify the target genes of these hormones in cultured human podocytes. |
