Effects of Akt signal pathway on the expression of NF-κB in renal tubular epithelial cells

Abstract

Objective To investigate the role of Akt signal pathway on the expression of monocyte chemoattractant protein-1 ( MCP-1 ) and nuclear transcription factor-κB (NF-κB) in renal tubular epithelial cells (HK-2) stimulated by albumin and to explore the mechanisms of action. Method The HK-2 cells were incubated in the presence of albumin (5,15,30 mg/mL) with or without Ly294002 (an inhibitor of Akt). Expression of mRNA was analyzed by reverse transcription-polymerase chain reaction (RT-PCR).Expression of Akt and protein MCP-1 were assessed by Western blot. Electrophoretic mobility shift assay (EMSA) was used to detect the activation of NF-κB. q-test was used to evaluate the differences in means between groups. Results Compared with control group, the expression of MCP-1 mRNA remarkly increased. [Control group: 0.233 ±0.01; BSA(5 mg/mL) group: 0.285 ±0.04; BSA( 15 mg/mL) group:0.387 ± 0.02; BSA ( 30 mg/mL) group: 0.473 ± 0.05; BSA ( 30 mg/mL) + Ly294002 group: 0. 325 ±0.05, P ＜ 0.05 ]. The expression of MCP-1 protein in renal interstitum of operation group were remarkly increased too. [ Control group: 100 ± 15.1; BSA ( 5 mg/mL) group: 148 ± 19.3; BSA ( 15 mg/mL) group: 176±20.7; BSA(30 mg/mL) group: 263 ± 18.1; BSA(30 mg/mL) + Ly294002 group: 175 ± 18.0, P ＜0.05 ]. Albumin stimulated the expression of MCP-1mRNA and protein in a dose-dependent manner. Albumin remarkably increased the activity of NF-κB. Albumin enhanced the expression of Akt. Ly294002 inhibited albumin-induced the expression of NF-κB and partially decreased the level of MCP-1. Apositive correlation was noted between NF-κB activation and MCP-1 expression( r = 0.68 ,P ＜ 0.01 ). Conclusions Albumin-induces MCP-1 and NF-κB production via Akt signal pathway in renal tubular epithelial cells. Key words: Renal tubular epithelial cells; Monocyte chemoattractant protein-1; Nuclear transcription factor-κB; Akt signal pathway; Albumin; Cell culture; Signal transduction; Ly294002