Roles and significance of CaMKⅡ and PLB in atrial remodeling in patients with atrial fibrillation

Objective To investigate the mRNA and protein and phosphorylation levels of phospholamban (PLB) and its regulatory protein Ca2+/calmodulin dependent protein kinase Ⅱ (CaMKⅡ) in right atrial tissue of patients with rheumatic heart disease (RHD), and explore their roles and significance in atrial fibrillation and atrial remodeling. Methods Right atrial tissue samples from 30 patients with rheumatic heart disease [12 males and 18 females, aged 24~68 (50.8±11.4) years] were collected from our institute during July and October 2017. The patients were assigned into the sinus rhythm group (n=11) and the atrial fibrillation rhythm group (n=19).The mRNA levels of CaMKⅡ and PLB were examined by RT-PCR, and protein levels of CaMKⅡp286, PLBp17 and PLB were measured by Western blotting. Results Compared with the sinus rhythm group, the mRNA levels of CaMKⅡ (0.006±0.003) and PLB (1.704±1.008) were significantly higher in the atrial fibrillation rhythm group (P < 0.05). While, similar trends were seen in the protein levels of CaMKⅡp286 (0.812±0.227) and PLBp17 (0.649±0.354) (P < 0.05), but the expression level of PLB was opposite (0.886±0.364, P < 0.05). Conclusion The mRNA levels of CaMKⅡ and PLB and the protein levels of CaMKⅡp286 and PLBp17 in atrial tissues are positively correlated with severity of atrial fibrillation. Therefore, decreasing PLB monomer and thus regulating PLB to control the cycle of calcium ions in atrial myocytes might be expected to a target for atrial remodeling therapy in atrial fibrillation.