Maintenance and Reversibility of Paroxysmal Atrial Fibrillation in JDP2 Overexpressing Mice

Figures

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  Figure 1. Experimental design of JDP2 overexpression. (A) Mice were fed with doxycycline diet until 5 weeks of age to suppress JDP2 overexpression in double transgenic mice. Then JDP2 overexpression was started by switching to standard diet. In group 1, JDP2 overexpression was stopped after 5 weeks, while in group 2, JDP2 overexpression was maintained over 10 weeks. WT mice received the same feeding protocols. ECG recordings were performed every week, starting at the time point of 5-week JDP2 overexpression. At the end of the experiments, hearts were removed to perform weight and expression analyses. (B) JDP2 mRNA expression was determined by real time RT-PCR (* p < 0.05 vs. WT, n = 9–13).

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  Figure 2. Conduction defects under prolonged JDP2 overexpression. ECGs were recorded over 30 min after 5 weeks of JDP2 overexpression, and then every week up to week 10, either in absence (group 1) or presence of JDP2 overexpression (group 2) (* p < 0.05 vs. WT, n = 9–12).

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  Figure 3. Paroxysmal atrial fibrillation under prolonged JDP2 overexpression. ECGs were recorded over 30 min after 5 weeks of JDP2 overexpression, and then every week up to week 10, either in absence (group 1) or presence of JDP2 overexpression (group 2). (A) Paroxysmal atrial fibrillation in mice overexpressing JDP2 for 10 weeks (upper panel), compared to sinus rhythm in WT mice (lower panel). (B) Mean duration times of atrial fibrillation (* p < 0.05 vs. WT, n = 9–13).

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  Figure 4. Organ weights in JDP2 mice. Lungs and hearts were harvested from mice after 5 weeks of JDP2 overexpression, followed by 5 weeks without overexpression (group 1) or another 5 weeks with JDP2 overexpression (group 2). The total heart weight (HW) and weights of left and right ventricles (LV and RV), atria, and lungs were determined and related to the body weight (BW) (* p < 0.05 vs. WT, n = 9–13).

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  Figure 5. Induction of hypertrophic and fibrotic mRNA expression under prolonged JDP2 overexpression. mRNA expression in atria of mice after 5 weeks of JDP2 overexpression, followed by 5 weeks without overexpression (group 1) or another 5 weeks with JDP2 overexpression (group 2) was determined by real time RT-PCR (* = p < 0.05 vs. WT, n = 9–13). The dashed line indicates the mRNA expression level in WTs.

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  Figure 6. Decreased mRNA expression of various calcium-handling proteins and connexins under prolonged JDP2 overexpression. mRNA expression in atria of mice after 5 weeks of JDP2 overexpression, followed by 5 weeks without overexpression (group 1) or another 5 weeks with JDP2 overexpression (group 2) by real time RT-PCR (* = p < 0.05 vs. WT, n = 9–13). The dashed line indicates the mRNA expression level in WTs.

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  Figure 7. No change in inflammatory marker gene expression. mRNA expression of the inflammatory marker genes in atria of mice after 5 weeks of JDP2 overexpression, followed by 5 weeks without overexpression (group 1) or another 5 weeks with JDP2 overexpression (group 2) by real time RT-PCR (n = 9–13). The dashed line indicates the mRNA expression level in WTs.

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  Figure 8. Expression of various calcium handling proteins with and without prolonged JDP2 overexpression. Original western blots and quantified data from atria isolated from mice after 5 weeks of JDP2 overexpression, followed by 5 weeks without overexpression (group 1) or another 5 weeks with JDP2 overexpression (group 2) (n = 8 per group; * p < 0.05, ns = non-significant). GAPDH was used as a loading control for normalization.

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  Figure 9. RyR expression and phosphorylation, and connexin 40 expression with and without prolonged JDP2 overexpression. Original western blots and quantified data from atria isolated from mice after 5 weeks of JDP2 overexpression followed by 5 weeks without overexpression (group 1) or another 5 weeks with JDP2 overexpression (group 2) (n = 8 per group; * p < 0.05; ** p < 0.01; **** p < 0.0001, ns = non-significant). GAPDH or vinculin was used as a loading control for normalization. Note that the GAPDH loading control shown for pS2808 is identical to the one shown in Figure 8 for CSQ, as the proteins were derived from the same membrane.