Figure 4. Effect of adenoviral UCH-L1 overexpression on ubiquitin proteasome system (UPS)-mediated degradation of p21WAF1/Cip1 (p21) proteins in cardiac fibroblasts.
A. Effect of adenoviral UCH-L1 overexpression on MG132 and PDGF-induced upregulation of p21 protein expression in rat neonatal cardiac fibroblasts. Quiescent cells infected with Ad-control or Ad-UCH-L1 were treated with or without MG132 (0.5 µM) and PDGF-BB (20 ng/ml) for 24 h. Left panel: representatives of immunoblotting. Right panel: quantitatively densitometric analysis of protein expression. Data is presented as fold change of ratio of target protein to internal control β-actin relative to the Ad-Control (-). n = 4, *p<0.05. B. Effect of PDGF on p21 protein ubiquitination as well as interaction of UCH-L1 and p21 proteins in rat neonatal cardiac fibroblasts. Quiescent cells were treated with or without PDGF-BB (20 ng/ml) for 24 h. W, whole cell lysates; IP, immunoprecitated; IB, immunoblotted. Input, 10 µg of whole cell lysates subjected to IB. All results are representatives of at least 4 separated experiments.