Effects of C-reactive protein on K+ channel interaction protein 2 in cardiomyocytes

Several studies have found that C-reactive protein (CRP) was associated with QTc interval prolongation and ventricular arrhythmia. However, little is known about the mechanisms involved. K+ channel interaction protein 2 (KChIP2) is a necessary subunit for the formation of transient outward potassium current (Ito.f) which plays a critical role in early repolarization and QTc interval of heart. In this study, we aimed to evaluate the effects of CRP on KChIP2 and Ito.f in cardiomyocytes and to explore the potential mechanism. The neonatal mice ventricular cardiomyocytes were cultured and treated with CRP at different concentrations. The expression of KChIP2 was detected by real time quantitative PCR and Western blot. In addition, Ito.f current density was evaluated by whole cell patch clamp techniques. Our results showed that CRP significantly decreased the mRNA and protein expression of KChIP2 in time and doses dependent manners (P < 0.05), and also reduced the current density of Ito.f (P < 0.05). In addition, CRP increased the expression of NF-kappa B and decreased I kappa B alpha expression without significant influence on the expression of ERK1/2 and JNK. Meanwhile, the NF-kappa B inhibitor PDTC significantly attenuated the effects of CRP on KChIP2 and Ito.f current density. In conclusion, CRP could significantly down-regulate KChIP2 expression and reduce current density of Ito.f partly through NF-kappa B pathway, suggesting that CRP may directly or indirectly influence QTc interval and arrhythmia via influencing KChIP2 expression and Ito.f current density of cardiomyocytes.