Fig. 4

CCRR knockdown causes destruction of intercalated discs and gap junction in healthy mice. a Representative images of electron microscopy (30,000× magnification) showing the effects of knockdown of endogenous CCRR by Lv-siCCRR on the microstructure of left ventricular cardiac muscles in healthy mice. Note the profound derangement and loss of intercalated discs in the hearts pretreated with Lv-siCCRR (dark arrows), resembling those noted in HF heart, which was not observed with Lv-siNC and Sham-Control (subjected to the surgical procedures but without lentivirus injection). Similar results were observed in another three independent experiments. b Effects of CCRR knockdown by Lv-siCCRR on the protein levels of Cx43 (left panel) and CIP85 (right panel) in healthy mice, with comparisons between the membrane and cytoplasm fractions. Lv-siCCRR elicited similar alterations of Cx43 and CIP85 levels in normal hearts as those seen above with HF hearts. Cx43 was decreased in the membrane fraction, but increased in the cytoplasm, with a net reduction of total protein levels. ^*P < 0.05, ^**P < 0.01, ^***P < 0.001 Lv-siCCRR vs. Sham; n = 6 mice for each group. CIP85 showed similar changes but with the total protein level unaffected. ^*P < 0.05, ^**P < 0.01 Lv-siCCRR vs. Sham; n = 5 heart samples of membrane fraction for each group, n = 6 for cytoplasmic fraction, and n = 6 for total protein. (Mean ± SEM; ANOVA followed by Dunnett’s test for multiple group comparisons, and Student t test for two group comparisons)