Figure 2.

The EGFR mediates transduction of compressive stress. a, NHBE cells exhibit basolaterally polarized distribution of EGFR (green) lining the LIS; cell nuclei are counterstained with propidium iodide (red). Scale bars indicate 2 μm. The EGFR is rapidly phosphorylated (Tyr 1068) in response to transcellular compressive stress (pressure). b, NHBE cells exhibit ERK phosphorylation after 30 min exposure to transcellular pressure (20–30 cm H₂O); this response is attenuated in the presence of the EGFR inhibitor AG 1478 but not the platelet-derived growth factor receptor inhibitor AG 1296, and is also attenuated by a function-blocking antibody that prevents ligand binding to the EGFR, a neutralizing antibody against HB-EGF, and the matrix metalloprotease inhibitor GM 6001, but not neutralizing antibodies against EGF and TGF-α. All blots are representative of at least two independent experiments. c, Representative images show the increased immunostaining (brown) for the phosphorylated EGFR (Tyr 1068) in mouse lungs perfused for 5 min with MCh (1 mM) relative to those perfused with PBS. The increased staining (percentage positive airways; asterisk = P < 0.0005, one-factorial analysis of variance and Bonferroni/Dunn test, n = 4–5, mean s.e.m.) was reversed by pre-treatment with isoproterenol (Mch + Isp), which abrogated the airway constriction. Perfusion with 10 ng ml⁻¹ HB-EGF is included as a positive control.