title: Stargazin-related protein γ₇ is associated with signalling endosomes in superior cervical ganglion neurons and modulates neurite outgrowth.
abstract: The role(s) of the newly discovered stargazin-like γ-subunit proteins remains unclear; although they are now widely accepted to be transmembrane AMPA receptor regulatory proteins (TARPs), rather than Ca²⁺ channel subunits, it is possible that they have more general roles in trafficking within neurons. We previously found that γ₇ subunit is associated with vesicles when it is expressed in neurons and other cells. Here, we show that γ₇ is present mainly in retrogradely transported organelles in sympathetic neurons, where it colocalises with TrkA-YFP, and with the early endosome marker EEA1, suggesting that γ₇ localises to signalling endosomes. It was not found to colocalise with markers of the endoplasmic reticulum, mitochondria, lysosomes or late endosomes. Furthermore, knockdown of endogenous γ₇ by short hairpin RNA transfection into sympathetic neurons reduced neurite outgrowth. The same was true in the PC12 neuronal cell line, where neurite outgrowth was restored by overexpression of human γ₇. These findings open the possibility that γ₇ has an essential trafficking role in relation to neurite outgrowth as a component of endosomes involved in neurite extension and growth cone remodelling.
authors: Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK.
authors: Dominic
authors: D
authors: Waithe
authors: Laurent
authors: L
authors: Ferron
authors: Annette C
authors: AC
authors: Dolphin
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