title: Neuropilin-1 biases dendrite polarization in the retina.
abstract: The majority of neurons in the nervous system exhibit a polarized morphology, with multiple short dendrites and a single long axon. It is clear that multiple factors govern polarization in developing neurons, and the biased accumulation of intrinsic determinants to one side of the cell, coupled with responses to asymmetrically localized extrinsic factors, appears to be crucial. A number of intrinsic factors have been identified, but surprisingly little is known about the identity of the extrinsic signals. Here, we show in vivo that neuropilin-1 (Nrp1) and its co-receptor plexinA1 (Plxna1) are necessary to bias the extension of the dendrites of retinal ganglion cells to the apical side of the cell, and ectopically expressed class III semaphorins (Sema3s) disrupt this process. Importantly, the requirement for Nrp1 and Plxna1 in dendrite polarization occurs at a developmental time point after the cells have already extended their basally directed axon. Thus, we propose a novel mechanism whereby an extrinsic factor, probably a Sema3, acts through Nrp1 and Plxna1 to promote the asymmetric outgrowth of dendrites independently of axon polarization.
authors.affiliation: Hotchkiss Brain Institute, Department of Cell Biology and Anatomy, University of Calgary, 3330 Hospital Drive, Calgary, AB T2N 4N1, Canada.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Kita
authors.forename: Gabriel E
authors.initials: GE
authors.lastname: Bertolesi
authors.forename: Carrie L
authors.initials: CL
authors.lastname: Hehr
authors.forename: Jillian
authors.initials: J
authors.lastname: Johnston
authors.forename: Sarah
authors.initials: S
authors.lastname: McFarlane
mesh_terms: D000818:Animals; D016764:Cell Polarity; D003712:Dendrites / Q000378:metabolism*; D005260:Female; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D039942:Neuropilin-1 / Q000378:metabolism*; D012160:Retina / Q000166:cytology* / Q000378:metabolism; D012165:Retinal Ganglion Cells / Q000166:cytology; D040121:Semaphorin-3A / Q000378:metabolism; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D009419:Nerve Tissue Proteins; C554429:PLXNA1 protein, Xenopus; D040121:Semaphorin-3A; D029867:Xenopus Proteins; D039942:Neuropilin-1
keywords: Plexin; Retinal ganglion cell; Semaphorin; Xenopus