Figure 11.

β₁AR is down-regulated, and β₂AR and USP33 are up-regulated in USP20–KO LVs. A, βAR subtypes in LV of WT and USP20–KO mice were measured by radioligand binding with ¹²⁵I-cyanopindolol and using the β₁AR subtype-selective antagonist CGP20712A as reported before (72, 74). Nonspecific binding was defined by the nonselective antagonist propranolol. Experiments were performed in triplicate. n = 21 for WT and n = 17 for USP20–KO. Error bars indicate average ± S.E. *, p < 0.05, ANOVA Bonferroni's post-test. B, bar graphs show relative proportion of β₁ and β₂ AR in USP20–KO and WT LVs calculated from the binding values shown in A. C, immunoblot (IB) of cardiac lysates from 3- to 4-month-old WT and USP20–KO mice probed with USP20, USP33, and GAPDH antibodies. D, band intensities of USP20 and USP33 normalized to GAPDH in each sample are shown and represented as means ± S.E. *, p < 0.05, versus USP33 in WT hearts, ANOVA, Bonferroni's post-test.