Presynaptic Type III Neuregulin1-ErbB signaling targets {alpha}7 nicotinic acetylcholine receptors to axons -- Data Supplement - JCB--Hancock et al. -- The Journal of Cell Biology

[HELP with High Resolution Image Viewing]

Figure S4. Type III Nrg1 back signaling regulates the surface expression of α7* nAChRs. Diagram summarizing a mechanism by which axonal Type III Nrg1 back signaling controls the levels of presynaptic α7* nAChRs. (A) Neuronal soma (nucleus, blue) and axons coexpressing Type III Nrg1 (green arrows) and α7* nAChRs (red horseshoes). A presynaptic specialization (PRE) forms an en passant synapse with an ErbB4 (blue arrow) expressing dendritic spine (POST). (B) ErbB4–Type III Nrg1 binding stimulates local signaling that activates PtdIns 3K/Akt. Signaling via PtdIns 3K/Akt stimulates local insertion of α7* nAChR–containing vesicles into the axon surface at, and/or adjacent to, presynaptic terminals (white circles). (C) As a consequence of Type III Nrg1 back signaling, the levels of presynaptic α7* nAChRs are up-regulated and available to mediate facilitation of neurotransmitter release in response to ACh or nicotine.