Yu-Hang Li1, Shi-Liang Yu1, Xiu-Guo Gan1, Shang-Ha Pan2, Yue-Qiu Teng3, Rui-Hua An4. 1. Department of Urology Surgery, First Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China. 2. Department of Central Laboratory, First Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China. 3. Department of Central Laboratory of Blood Cancer, First Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China. 4. Department of Urology Surgery, First Affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China. RuiHuaAn@126.com.
Abstract
OBJECTIVES: We investigated the possible involvement of multidrug resistance protein 1 P-glycoprotein (MDR1 P-gp) in the oxalate-induced redistribution of phosphatidylserine in renal epithelial cell membranes. METHODS: Real-time PCR and western blotting were used to examine MDR1 expression in Madin-Darby canine kidney cells at the mRNA and protein levels, respectively, whereas surface-expressed phosphatidylserine was detected by the annexin V-binding assay. RESULTS: Oxalate treatment resulted in increased synthesis of MDR1, which resulted in phosphatidylserine (PS) externalization in the renal epithelial cell membrane. Treatment with the MDR1 inhibitor PSC833 significantly attenuated phosphatidylserine externalization. Transfection of the human MDR1 gene into renal epithelial cells significantly increased PS externalization. CONCLUSIONS: To our knowledge, this study is the first to show that oxalate increases the synthesis of MDR1 P-gp, which plays a key role in hyperoxaluria-promoted calcium oxalate urolithiasis by facilitating phosphatidylserine redistribution in renal epithelial cells.
OBJECTIVES: We investigated the possible involvement of multidrug resistance protein 1 P-glycoprotein (MDR1P-gp) in the oxalate-induced redistribution of phosphatidylserine in renal epithelial cell membranes. METHODS: Real-time PCR and western blotting were used to examine MDR1 expression in Madin-Darby canine kidney cells at the mRNA and protein levels, respectively, whereas surface-expressed phosphatidylserine was detected by the annexin V-binding assay. RESULTS:Oxalate treatment resulted in increased synthesis of MDR1, which resulted in phosphatidylserine (PS) externalization in the renal epithelial cell membrane. Treatment with the MDR1 inhibitor PSC833 significantly attenuated phosphatidylserine externalization. Transfection of the humanMDR1 gene into renal epithelial cells significantly increased PS externalization. CONCLUSIONS: To our knowledge, this study is the first to show that oxalate increases the synthesis of MDR1P-gp, which plays a key role in hyperoxaluria-promoted calcium oxalate urolithiasis by facilitating phosphatidylserine redistribution in renal epithelial cells.