title: LC3 binding to the scaffolding protein JIP1 regulates processive dynein-driven transport of autophagosomes.
abstract: Autophagy is essential for maintaining cellular homeostasis in neurons, where autophagosomes undergo robust unidirectional retrograde transport along axons. We find that the motor scaffolding protein JIP1 binds directly to the autophagosome adaptor LC3 via a conserved LIR motif. This interaction is required for the initial exit of autophagosomes from the distal axon, for sustained retrograde transport along the midaxon, and for autophagosomal maturation in the proximal axon. JIP1 binds directly to the dynein activator dynactin but also binds to and activates kinesin-1 in a phosphorylation-dependent manner. Following JIP1 depletion, phosphodeficient JIP1-S421A rescues retrograde transport, while phosphomimetic JIP1-S421D aberrantly activates anterograde transport. During normal autophagosome transport, residue S421 of JIP1 may be maintained in a dephosphorylated state by autophagosome-associated MKP1 phosphatase. Moreover, binding of LC3 to JIP1 competitively disrupts JIP1-mediated activation of kinesin. Thus, dual mechanisms prevent aberrant activation of kinesin to ensure robust retrograde transport of autophagosomes along the axon.
authors.affiliation: Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: Meng-Meng
authors.initials: MM
authors.lastname: Fu
authors.affiliation: Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Nirschl
authors.affiliation: Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA. Electronic address: holzbaur@mail.med.upenn.edu.
authors.forename: Erika L F
authors.initials: ELF
authors.lastname: Holzbaur
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D001343:Autophagy / Q000502:physiology*; D001370:Axonal Transport / Q000502:physiology*; D054638:Dual Specificity Phosphatase 1 / Q000378:metabolism; D000072159:Dynactin Complex; D004398:Dyneins / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D047468:Immunoprecipitation; D016547:Kinesins / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000378:metabolism / Q000502:physiology*; D010588:Phagosomes; D010766:Phosphorylation
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000072159:Dynactin Complex; C480860:Map1lc3b protein, mouse; C490665:Mapk8ip protein, mouse; D008869:Microtubule-Associated Proteins; D054638:Dual Specificity Phosphatase 1; C517020:Dusp1 protein, mouse; D004398:Dyneins; D016547:Kinesins