Effects of high-dose uric acid on cellular proteome, intracellular ATP, tissue repairing capability and calcium oxalate crystal-binding capability of renal tubular cells: Implications to hyperuricosuria-induced kidney stone disease.

ABSTRACT

Hyperuricosuria is associated with kidney stone disease, especially uric acid (UA) and calcium oxalate (CaOx) types. Nevertheless, detailed mechanisms of hyperuricosuria-induced kidney stone formation remained unclear. This study examined changes in cellular proteome and function of renal tubular cells after treatment with high-dose UA for 48-h. Quantitative proteomics using 2-DE followed by nanoLC-ESI-ETD MS/MS tandem mass spectrometry revealed significant changes in levels of 22 proteins in the UA-treated cells. These proteomic data could be confirmed by Western blotting. Functional assays revealed an increase in intracellular ATP level and enhancement of tissue repairing capability in the UA-treated cells. Interestingly, levels of HSP70 and HSP90 (the known receptors for CaOx crystals) were increased in apical membranes of the UA-treated cells. CaOx crystal-cell adhesion assay revealed significant increase in CaOx-binding capability of the UA-treated cells, whereas neutralization of the surface HSP70 and/or HSP90 using their specific monoclonal antibodies caused significant reduction in such binding capability. These findings highlighted changes in renal tubular cells in response to high-dose UA that may, at least in part, explain the pathogenic mechanisms of hyperuricosuria-induced mixed kidney stone disease.