Figures & data
Figure 1 Dynamics of the lamellipodia formation in migrating macrophages. Macrophages plated on fibronectin coated glass bottom dishes (MatTek) were stimulated with 100 nM fMLP and imaged at 37°C in CO2 independent media. Movie frame rates were captured every 5 min over 3 h. Images were captured using Metamorph V67.1 software (Molecular Devices, Sunnyvale, CA) and edited using ImageJ. Selected frames are shown.
Figure 2 The SNARE complex Stx4/SNAP23/VAMP 3 regulates incorporation of recycling endosome membrane into lamellipodia. (A) The R-SNARE VAMP3 on the recycling endosome forms a complex with its cognate partner Q-SNARE complex Stx4/SNAP23 on the cell surface to mediate incorporation of the recycling endosome membrane in the leading edge. (B) Integrin α5β1 (the fibronectin receptor) is endocytosed from the cell surface and trafficked through the early endosome to the VAMP3-positive recycling endosome. Integrin α5β1 is then recycled to the leading edge through the incorporation of the recycling endosome membrane at the leading edge, this not only delivers the cargo integrin to the leading edge but also adds extra membrane for expansion of the lamellipodia. Stx4/SNAP23 translocates to the leading edge in migrating cells where it acts as the surface Q-SNARE that partners VAMP 3 to regulate incorporation of recycling endosome membrane.
