OBJECTIVETo investigate the expression of integrin-linked kinase (ILK) in kidneys of mice with unilateral ureteral obstruction and its relevance with the epithelial-mesenchymal transition.

METHODSMice were randomly divided into two groups, sham operation (C, n = 20) and unilateral ureteral obstruction (UUO, n = 40). The animals were sacrificed at day 1, 3, 7 and 14 respectively after the surgery. Tubulointerstitial fibrosis (TIF) was graded according to Masson staining. The protein level of ILK was examined by Western blot. Tissue/cytological expression for ILK, alpha-SMA and E-cadherin were investigated by immunohistochemistry. The mRNA levels of ILK, alpha-SMA and E-cadherin were analyzed by quantitative real-time PCR.

RESULTSIn the control animals (group C), weak staining for ILK was detected mainly in the podocytes. Significant increase of staining for ILK in the experimental mice (UUO group) was detected from day 1 onward (t = 16.5, P < 0.01), reaching the peak at day 7. The protein expression of E-cadherin was continuously down-regulated from day 3 onward after surgery (t = 21.0, P < 0.01), while expression for alpha-SMA was up-regulated. From day 1 to day 7, the protein expression of ILK was positively correlated with alpha-SMA (R = 0.88, P < 0.01), but negatively correlated with E-cadherin (R = -0.87, P < 0.01). The mRNA expression of ILK and alpha-SMA analyzed by real-time PCR increased from postoperative day 1 and 3 respectively, but the mRNA expression of E-cadherin decreased from day 3 onward.

CONCLUSIONIncreasing expression of ILK occurs in the early phase of UUO mouse and may play an important role in the process of TIF through mediating the epithelial-mesenchymal transition.