Figure 2. Schwann cells extend pseudopods selectively in response to juxtacrine-like neuronal signals.

(a) Activation of Akt in Schwann cells by neuronal membrane suspensions. Neuronal membranes were added to Schwann cells, protein lysates were probed for p-Akt, Akt and β-Tubulin. Soluble Neuregulin1 was used as a positive control. (c–f) Confocal images of Schwann cell pseudopods and cell bodies in response to the indicated stimuli in the bottom chamber. Cells were stained for F-actin with TRITC-phalloidin and DAPI. (c) No stimulus (DMEM). (d) Soluble neuregulin 1 (NRG1s). (e) DRG neurons in defined media plated on the bottom chamber, at 0.2-mm distance below the microporous surface. (f) DRG neurons were solubilized and the membrane suspension was added to the bottom chamber. Only this latter condition caused the extension of polarized pseudopods. (b) Quantification by BCA of the protein content of Schwann cell pseudopod and cell bodies in the conditions indicated. Error bars indicate s.d. n=5 independent experiments. Statistical analyses were performed using one-way ANOVA, ****P< 0.0001. (g) Western blots from Schwann cell pseudopods and cell body protein lysates, after induction by neuronal membranes. Equal amount of proteins were separated by SDS/PAGE probed for the indicated proteins and stained with amido black. Scale bar, 40 μm.