E3 ligase Nedd4 promotes axon branching by downregulating PTEN.
Regulated protein degradation via the ubiquitin-proteasome system (UPS) plays a central role in building synaptic connections, yet little is known about either which specific UPS components are involved or UPS targets in neurons. We report that inhibiting the UPS in developing Xenopus retinal ganglion cells (RGCs) with a dominant-negative ubiquitin mutant decreases terminal branching in the tectum but does not affect long-range navigation to the tectum. We identify Nedd4 as a prominently expressed E3 ligase in RGC axon growth cones and show that disrupting its function severely inhibits terminal branching. We further demonstrate that PTEN, a negative regulator of the PI3K pathway, is a key downstream target of Nedd4: not only does Nedd4 regulate PTEN levels in RGC growth cones, but also, the decrease of PTEN rescues the branching defect caused by Nedd4 inhibition. Together our data suggest that Nedd4-regulated PTEN is a key regulator of terminal arborization in vivo.
Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK.
Jovana
J
Drinjakovic
Hosung
H
Jung
Douglas S
DS
Campbell
Laure
L
Strochlic
Asha
A
Dwivedy
Christine E
CE
Holt
D000818:Animals; D001120:Arginine / Q000235:genetics; D001369:Axons / Q000502:physiology*; D002461:Cell Line, Transformed; D015536:Down-Regulation / Q000235:genetics / Q000502:physiology*; D018274:Electroporation / Q000379:methods; D004625:Embryo, Nonmammalian; D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology; D049452:Green Fluorescent Proteins / Q000235:genetics; D020439:Growth Cones / Q000502:physiology*; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D008239:Lysine / Q000235:genetics; D018613:Microscopy, Confocal / Q000379:methods; D009154:Mutation / Q000235:genetics; D000075702:Nedd4 Ubiquitin Protein Ligases; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D012160:Retina / Q000166:cytology; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D013477:Superior Colliculi / Q000166:cytology; D046509:Tissue Culture Techniques; D014161:Transduction, Genetic / Q000379:methods; D025801:Ubiquitin / Q000235:genetics; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D014981:Xenopus; D029867:Xenopus Proteins
D056827:Endosomal Sorting Complexes Required for Transport; D025801:Ubiquitin; D029867:Xenopus Proteins; D049452:Green Fluorescent Proteins; D001120:Arginine; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618482:Nedd4 protein, Xenopus; C000618483:Nedd4 protein, human; C000618460:nedd4l protein, Xenopus; D044767:Ubiquitin-Protein Ligases; D019869:Phosphatidylinositol 3-Kinases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D008239:Lysine