Effect of chronic renal failure medium on the ubiquitin‑proteasome pathway of arterial muscle cells.

The ubiquitin‑proteasome pathway (UPP) is involved in the occurrence and development of atherosclerosis through inhibitor of κB (IκB) degradation which activates nuclear factor-κB (NF‑κB). However, the correlation between UPP and vascular complications of uramia remains unknown. The aim of the present study was to determine whether the UPP is activated in aortic smooth muscle cells (ASMCs) when cultured with uremic serum and to examine the role of the UPP on the dysfunction of ASMCs in uremia. ASMCs were cultured with pooled normal sera or chronic renal failure sera. The mRNA expression levels for ubiquitin (Ub) and Ub-activating enzyme (E1) were analyzed using reverse transcription PCR and levels of the ubiquitinated proteins E1 and IκBα were measured using western blot analysis. The enzymatic activities of three 20S proteasomes were examined using specific fluorogenic peptide substrates. Compared with normal serum, chronic renal serum increased E1 mRNA and protein expression of rabbit ASMCs (both P<0.01). In addition, the mRNA expression of Ub also increased and the expression of IκBα was observed to decrease significantly (both P<0.01). Ubiquitinated proteins in the normal and chronic renal failure groups were not found to be significantly different, but the activity of proteasomes increased significantly (P<0.01). Chronic renal failure medium induced the activation of the UPP in ASMCs.