Ligation of protease-activated receptor 1 enhances α_v β₆ integrin–dependent TGF-β activation and promotes acute lung injury
J. Clin. Invest. R. Gisli Jenkins, et al. 116:1606 doi:10.1172/JCI27183 [Go to this article.]

Figure 5
PAR1 signals via RhoA and Rho kinase to induce α_v β₆ -mediated TGF-β activation. (A) WT mouse embryonic fibroblasts expressing α_vβ₆ (MEFβ6) were adenovirally infected with GFP, constitutively active (CA) RhoA, or dominant-negative (DN) RhoA. After infection and cell sorting, cells were stimulated (white bars) or were not stimulated (black bars) with 10 μM SFLLRN, and β₆-dependent TGF-β activity was calculated from coculture bioassays with TML cells. Unstimulated Par1^–/– cells expressing α_vβ₆ were also infected with an adenovirus encoding a constitutively active RhoA, dominant-negative RhoA, or GFP control and studied in coculture bioassays, as above. (B) IMLE cells and mouse embryonic fibroblasts, both expressing the β₆ integrin, were stimulated with 10 μM SFLLRN (dashed lines) in the presence of increasing doses of the Rho kinase inhibitor Y-27632, and α_vβ₆-mediated TGF-β activity was compared with that of unstimulated IMLE cells (solid lines). (C) MEFβ6 cells were stimulated with 10 μM SFLLRN or 500 pg/ml TGF-β for 4 hours in the presence or absence of the Rho kinase inhibitor Y-27632 and an α_vβ₆ blocking antibody, and compared with unstimulated cells. Cell lysates were analyzed by Western blotting for phospho-Smad2 or total Smad2. All results are representative of at least 3 independent experiments. *P < 0.005.