Fig. 6.

Upregulation of ASIC-1 membrane expression by cell adhesion to fibronectin requires integrin-β₁. A and C: stable D54MG cell lines β₁-KD and β₁-Scr were transfected with ASIC-1-GFP. After 72 h, cells were incubated on fibronectin-coated dishes or on uncoated plates for 24 h; then total, as well as biotinylated, surface proteins were immunoblotted for GFP and integrin-β₁. No increase in plasma membrane expression of ASIC-1 was observed in β₁-KD cells with fibronectin-mediated cell adhesion (n ≥ 3). In contrast, a significant increase (n ≥ 3) in membrane localization of ASIC-1, as well as integrin-β₁, after fibronectin-mediated integrin activation was observed in β₁-Scr cells (C). p27^KIP1 was used as a loading control and to demonstrate lack of biotinylation of intracellular proteins. B and D: normalized densitometry of membrane ASIC-1, integrin-β₁, and Na⁺-K⁺-ATPase in D54MG β₁-KD and β₁-Scr cells transfected with ASIC-1-GFP and incubated on fibronectin-coated dishes or on uncoated plates for 24 h. ***P < 0.001.