Albumin overload induces ?-smooth muscle actin expression in proximal tubular epithelial cells / 中国病理生理杂志

ABSTRACT

AIM:To study whether albumin overload in proximal tubular epithelial cells(PTCs)induces epithelial to myofibroblast transdifferentiation(EMT).METHODS:Rat renal proximal tubular cell line NRK52E was cultured on 6 well plates.When the cells reached 70% confluens or complete confluens,cells were serum starved for 24 h.Different concentrations of delipidated bovine serum albumin(dBSA),ranging from 0-30 g/L,were then added to the cells.The media was changed every 48 h until the end of 144 h.Cell shapes were monitored by light microscope during experiment.Cell structures were detected by electron microscopy.Epithelial cell markersE-cadherin,?-catenin,and myofibroblast marker?-smooth muscle actin(?-SMA)were detected by immunofluorescent microscopy and Western blotting.RESULTS:dBSA overload induced the expression of ?-SMA in sub-confluent NRK52E,and a few cells elongated,but the induced expression of ?-SMA was not in a dose dependent manner.dBSA overload did not induce the expression of ?-SMA in complete confluent NRK52E,cell shape did not change either.dBSA overload did not inhibit expression of E-cadherin or ?-catenin both in sub-confluent and complete confluent NRK52E.The electron microscope showed that these cells retained epithelial phenotype,with microvilli and tight junction.CONCLUSION:Albumin overload induces PTCs expressing myofibroblast marker ?-SMA and promotes EMT.However,complete EMT does not achieve.Complete confluens(cell-cell contacts)inhibits albumin induced ?-SMA expression in PTCs.