Figure 1.

Agonist regulation of β₂AR and let-7f in HASM cells. A, B) HASM cells from nonasthmatic or asthmatic lung donors were maintained in culture and treated with 100 µM ascorbic acid (control) or ascorbic acid with 30 µM ISO for 18 h at 37°C. RNA and protein were derived from these cells and let-7f miRNA and β₂AR protein expression were determined as described in Materials and Methods (n = 4 experiments each from a different donor). C) The 2 greatest and 2 least changes in β₂AR expression found in experiments from panels A and B are indicated with the changes in let-7f levels. D) ADRB2 mRNA is not altered in HASM cells by 18 h ISO treatment (n = 4 experiments from the D9 line). E) Knockdown of let-7f attenuates ISO-promoted down-regulation of β₂AR in HASM cells (n = 6 experiments) *P < 0.01.