Fig. 5.

The beta-2 receptor mediates the activity of beta agonists on DUX4 expression. a–c Concentration response curves for clenbuterol (CB) alone or in combination with the beta-1 selective antagonist atenolol (a), the beta-2 selective antagonist ICI-118,551 (b), or the beta-3 selective antagonist L-748,337 (c) on MBD3L2 expression in MB200 FSHD2 myoblasts. d EC₅₀s of clenbuterol alone or in combination with selective antagonists, indicated in picomolar (pM) concentrations with 95% confidence intervals (CI). e Expression of DUX4, DUX4 target genes, and the beta-2 receptor ADRB2 after ADRB2 siRNA knockdown in MB200 FSHD2 cells differentiated for 48 h with 1 nM formoterol or DMSO vehicle control added during the final 8 h. f Beta-2 adrenergic receptor (β2-AR) protein levels after ADRB2 knockdown as described in e. Error bars indicate the standard deviation from the mean of three biological replicates. α-Tubulin serves as a loading control. p values were calculated using a two-tailed, two-sample Student’s t test assuming unequal variance. *p < 0.05