title: ESCRT-II controls retinal axon growth by regulating DCC receptor levels and local protein synthesis.
abstract: Endocytosis and local protein synthesis (LPS) act coordinately to mediate the chemotropic responses of axons, but the link between these two processes is poorly understood. The endosomal sorting complex required for transport (ESCRT) is a key regulator of cargo sorting in the endocytic pathway, and here we have investigated the role of ESCRT-II, a critical ESCRT component, in Xenopus retinal ganglion cell (RGC) axons. We show that ESCRT-II is present in RGC axonal growth cones (GCs) where it co-localizes with endocytic vesicle GTPases and, unexpectedly, with the Netrin-1 receptor, deleted in colorectal cancer (DCC). ESCRT-II knockdown (KD) decreases endocytosis and, strikingly, reduces DCC in GCs and leads to axon growth and guidance defects. ESCRT-II-depleted axons fail to turn in response to a Netrin-1 gradient in vitro and many axons fail to exit the eye in vivo These defects, similar to Netrin-1/DCC loss-of-function phenotypes, can be rescued in whole (in vitro) or in part (in vivo) by expressing DCC. In addition, ESCRT-II KD impairs LPS in GCs and live imaging reveals that ESCRT-II transports mRNAs in axons. Collectively, our results show that the ESCRT-II-mediated endocytic pathway regulates both DCC and LPS in the axonal compartment and suggest that ESCRT-II aids gradient sensing in GCs by coupling endocytosis to LPS.
authors.affiliation: Department of Physiology Development Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK.
authors.forename: Filip A
authors.initials: FA
authors.lastname: Konopacki
authors.affiliation: Department of Physiology Development Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK.
authors.forename: Hovy Ho-Wai
authors.identifier: http://orcid.org/0000-0003-3317-478X
authors.initials: HH
authors.lastname: Wong
authors.affiliation: Department of Physiology Development Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK.
authors.forename: Asha
authors.initials: A
authors.lastname: Dwivedy
authors.affiliation: Department of Physiology Development Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK.
authors.forename: Anaïs
authors.initials: A
authors.lastname: Bellon
authors.affiliation: Department of Molecular Biology, Harvard Medical School, Simches Research Center, Boston, MA 02114, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Blower
authors.affiliation: Department of Physiology Development Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK ceh33@cam.ac.uk.
authors.forename: Christine E
authors.identifier: http://orcid.org/0000-0003-2829-121X
authors.initials: CE
authors.lastname: Holt
mesh_terms: D000818:Animals; D001369:Axons / Q000187:drug effects / Q000378:metabolism*; D000075389:DCC Receptor; D004705:Endocytosis / Q000187:drug effects; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism*; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism; D055785:Gene Knockdown Techniques; D020439:Growth Cones / Q000187:drug effects / Q000378:metabolism; D009414:Nerve Growth Factors / Q000494:pharmacology; D000075388:Netrin-1; D010641:Phenotype; D014176:Protein Biosynthesis / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D012160:Retina / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000494:pharmacology; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D000075389:DCC Receptor; C000613068:DCC protein, Xenopus; D056827:Endosomal Sorting Complexes Required for Transport; D009414:Nerve Growth Factors; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D025521:Tumor Suppressor Proteins; D029867:Xenopus Proteins; D000075388:Netrin-1
keywords: DCC; ESCRT; Netrin-1; axon guidance; endocytosis; protein synthesis