FIGURE 7.

Expression of claudin 14 in cultured cardiomyocytes and hypertrophied heart. A, effect of knockdown of Gα₁₆ and TFE3 on the level of claudin 14 mRNA in cultured cardiomyocytes. Neonatal cardiomyocytes (NCM) were transfected with each siRNA and/or universal control siRNA (Stealth RNAi Negative Control, Invitrogen). Forty-eight hours after transfection, the level of mRNA of Gα₁₆ (A), TFE3 (B), and claudin 14 (C) were analyzed by real time PCR. Transfection efficiency of siRNA was estimated at 70–80% using FITC-labeled double strand RNA (Block It Fluorescent Oligo, Invitrogen) (right panel). *, p < 0.05 versus negative siRNA. Data are expressed as the mean ± S.E. of seven to eight independent experiments. B and C, expression of claudin 14 in the mouse cardiac hypertrophy model. B, the left ventricular expression of claudin 14 mRNA was analyzed by real time PCR. Control refers to the sham-operated or saline-infused mouse. Data are expressed as the -fold change in claudin 14 level from that in control group. Data are expressed as the mean ± S.E. of five experiments with duplicate determinations. C, immunohistochemical staining for claudin 14 (1:100; brown) of the left ventricle of sham- or TAC-operated mouse. A frozen section (8 μm) of the mouse heart was subjected to immunohistochemical staining as described under “Experimental Procedures”. Blue, nucleus. ISO, continuous infusion of isoproterenol. *, p < 0.05 versus control group.