FIGURE 4.

α_V integrins are enriched at tips of Schwann cell (SC) protrusions. (a,b) Scrambled- and si-α_V^#2-treated SCs were labeled with cell tracker (CT) green, then plated on fibronectin (FN)-coated coverslips for 3.5 hr. Cells were costained with anti-α_V Ab (red), anti-tubulin Ab (Tub, cyan), and DAPI (blue). (a/a′/a′′) α_V integrin was detected at tips of protruding lamellae, particularly at membrane ruffles (arrowheads) and leading edges (arrows). (b/b′/b′′) α_V-silenced SCs lacked α_V integrin immunoreactivity at the tips. Also, the diffused cytoplasmic staining diminished. (c/c′/c′′) When seeded on neurons for 3.5 hr, α_V integrin concentrated at tips of the SC process and at sites of axon contact (arrows). Cells were costained with anti-neurofilament (NF) Ab (cyan) to label neurons. (d/d′) In contrast, α_V integrin was absent along the body of already elongated SCs on axons. (e/e′/e′′,f/f′) α_V-silenced SCs with short (e/e′/e′′) or long (f) processes had no α_V integrin immunoreactivity. All are Z-stack images acquired using identical confocal settings. Scale bar = 30 μm in all panels. Images are representative of at least four replicates. SCs were seeded on neurons at a density of 20,000