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. 2010 Mar 17;30(11):4120–4131. doi: 10.1523/JNEUROSCI.5185-09.2010

Figure 2.

Figure 2.

Distribution of polarized vesicular markers, phosphoinositides, PI3K, and PTEN in myelinating Schwann cells. Arrows and arrowheads are as in Figure 1. A, Immunostaining of syntaxin4 (syn4, red) and sec8 (red) reveals the localizations of these proteins in the abaxonal domain with partial colocalization with E-cadherin (green). B, Syntaxin4 (red) is present in the outer region of paranodal loops [E-cadherin (green)]. C, Immunostaining of annexin A2 (Anx2, red) shows its localization in the adaxonal domain and in SL incisures, where Anx2 colocalizes with E-cadherin (green). D, Immunostaining of syntaxin4 (syn4, green), integrin β1 (blue), and NF (red) in sciatic nerve cross sections. Syntaxin 4 colocalizes with integrin β1 in the abaxonal domain. E, No colocalization can be seen between syntaxin4 (red) and MAG-GFP (green) in Schwann cells in sciatic cross sections. A, Axon. F, Upper panel, PI3K (red) and PTEN (green) are localized in abaxonal and adaxonal domains (and SL incisures), respectively, in teased fibers. Lower panel, Overlay of PTEN (green) and E-cadherin (blue) shows their colocalization in SL incisures. G, Left, Immunostaining of PTEN (green), integrin β1 (blue), and NF (red) on nerve cross sections shows PTEN localization around the axon (stained for neurofilaments), confirming that PTEN is expressed in the adaxonal domain of SCs. Scale bar, 2.5 μm. Right, Immunostaining of PI3K (red) on Schwann cells expressing MAG-GFP (green) shows no colocalization in the adaxonal domain. A, Axon. H, PI3K (green) colocalizes with integrin β1 (blue) in the abaxonal domain. NF (red) staining shows axons in sciatic nerve cross sections. I, A myelinating Schwann cell expressing GFP-PH-PLCδ (green) shows the probe localization in SL incisures and in the adaxonal domain. No colocalization is observed with PI3K (red) in the abaxonal domain. J, GFP labeling at a node of Ranvier of a cell expressing GFP-PH-PLCδ is enriched in the inner part of paranodal loops. K, A myelinating Schwann cell expressing GFP-PH-AKT (green) show its localization in all compartments with enrichment in the abaxonal domain, where the probe colocalizes with integrin β1 (red). L, Upper panel, GFP-PH-AKT (green) is enriched in the outer region of paranodal loops at a node of Ranvier. Lower panel, The same probe is present in the perinuclear area and in Cajal bands (yellow arrows, abaxonal domain). n, Nucleus. M, This schematic drawing shows the structure of a myelinating Schwann cell, the characterized polarity domains, and a summary of the observed localizations of markers. Tissue was from 2-month-old mice, except for stainings of cells expressing GFP probes, for which mice were 10–20 d old. Unless otherwise indicated, all scale bars are 5 μm. OV, Overlay.