Expression and localization of ID complex proteins in HSPB7 CKO hearts.

(A) Confocal micrographs of longitudinal sections of the cardiac muscle of control and CKO mice at d7 after tamoxifen administration. Specific antibodies were used to identify the distributions of intercalated disc components: N-cadherin, desmoplakin, vinculin, and connexin 43. In HSPB7 CKO hearts, the staining of desmoplakin and N-cadherin were distributed throughout the cytoplasm, but little was observed in control hearts. Connexin 43 was absent from the intercalated discs in HSPB7 CKO hearts. The insets show representative areas at a higher magnification. The nucleus was visualized through Hoechst 33342 staining. n = 4 per group. Scale bar: 20 μm. (B) Immunoblotting of intercalated discs and sarcomeric-associated proteins in HSPB7 CKO and control hearts. GAPDH signal shows the loading of the samples between the lanes. n = 4 per group. (C) Quantitative analysis of immunoblot analysis of protein levels in cardiac tissue from control and CKO mice. Seven days after the first tamoxifen injections, connexin 43 protein expression dropped to < 40% in CKO animals, as determined by immunoblot analysis. Data are presented as means ± SD. *, P < 0.05, **, P < 0.01 relative to control.