Calcium- and integrin-binding protein-1 and calcineurin are upregulated in the right atrial myocardium of patients with atrial fibrillation

AIMS: The aim of this study was to determine whether altered expression and distribution of calcium- and integrin-binding protein-1 (CIB1) is involved in the pathogenesis of different types of patients with atrial fibrillation (AF) associated with valvular heart disease (VHD). METHODS AND RESULTS: Right atrial specimens obtained from 65 patients undergoing valve replacement surgery were divided into three groups: sinus rhythm group (n= 24), paroxysmal atrial fibrillation group (PaAF; n= 10), and persistent atrial fibrillation group (PeAF; AF lasting >6 month; n= 31). The expression levels of mRNA and protein content for CIB1, calcineurin B, calcineurin A, and Na(+)-Ca(2+) exchanger-1 (NCX1) were measured. We also measured the combination of CIB1 with calcineurin B, L-type Ca(2+) channel, and NCX1 using immunoprecipitation. Expression of mRNA and protein content of CIB1, calcineurin B, calcineurin A, and NCX1 was increased in the AF group. Calcium- and integrin-binding protein-1 interacted with calcineurin B and L-type Ca(2+) channel. Surprisingly, CIB1 also combined with NCX1. CONCLUSIONS: The CIB1 and calcineurin expression was increased in AF atrial tissue and was related to the type of AF. This finding suggests that CIB1 may be involved in the pathogenesis of AF in VHD patients.