Dataset Information

FIGNL1 associates with KIF1B? and BICD1 to restrict dynein transport velocity during axon navigation.

ABSTRACT: Neuronal connectivity relies on molecular motor-based axonal transport of diverse cargoes. Yet the precise players and regulatory mechanisms orchestrating such trafficking events remain largely unknown. We here report the ATPase Fignl1 as a novel regulator of bidirectional transport during axon navigation. Using a yeast two-hybrid screen and coimmunoprecipitation assays, we showed that Fignl1 binds the kinesin Kif1b? and the dynein/dynactin adaptor Bicaudal D-1 (Bicd1) in a molecular complex including the dynactin subunit dynactin 1. Fignl1 colocalized with Kif1b? and showed bidirectional mobility in zebrafish axons. Notably, Kif1b? and Fignl1 loss of function similarly altered zebrafish motor axon pathfinding and increased dynein-based transport velocity of Rab3 vesicles in these navigating axons, pinpointing Fignl1/Kif1b? as a dynein speed limiter complex. Accordingly, disrupting dynein/dynactin activity or Bicd1/Fignl1 interaction induced motor axon pathfinding defects characteristic of Fignl1 gain or loss of function, respectively. Finally, pharmacological inhibition of dynein activity partially rescued the axon pathfinding defects of Fignl1-depleted larvae. Together, our results identify Fignl1 as a key dynein regulator required for motor circuit wiring.

SUBMITTER: Atkins M

PROVIDER: S-EPMC6781435 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

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FIGNL1 associates with KIF1Bβ and BICD1 to restrict dynein transport velocity during axon navigation.

Atkins Melody M Gasmi Laïla L Bercier Valérie V Revenu Céline C Del Bene Filippo F Hazan Jamilé J Fassier Coralie C

The Journal of cell biology 20190919 10

Neuronal connectivity relies on molecular motor-based axonal transport of diverse cargoes. Yet the precise players and regulatory mechanisms orchestrating such trafficking events remain largely unknown. We here report the ATPase Fignl1 as a novel regulator of bidirectional transport during axon navigation. Using a yeast two-hybrid screen and coimmunoprecipitation assays, we showed that Fignl1 binds the kinesin Kif1bβ and the dynein/dynactin adaptor Bicaudal D-1 (Bicd1) in a molecular complex inc ...[more]

PMID: 31541015

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Project description:Neurodevelopment, plasticity, and cognition are integral with functional directional transport in neuronal axons that occurs along a unique network of discontinuous polar microtubule (MT) bundles. Axonopathies are caused by brain trauma and genetic diseases that perturb or disrupt the axon MT infrastructure and, with it, the dynamic interplay of motor proteins and cargo essential for axonal maintenance and neuronal signaling. The inability to visualize and quantify normal and altered nanoscale spatio-temporal dynamic transport events prevents a full mechanistic understanding of injury, disease progression, and recovery. To address this gap, we generated DyNAMO, a Dynamic Nanoscale Axonal MT Organization model, which is a biologically realistic theoretical axon framework. We use DyNAMO to experimentally simulate multi-kinesin traffic response to focused or distributed tractable injury parameters, which are MT network perturbations affecting MT lengths and multi-MT staggering. We track kinesins with different motility and processivity, as well as their influx rates, in-transit dissociation and reassociation from inter-MT reservoirs, progression, and quantify and spatially represent motor output ratios. DyNAMO demonstrates, in detail, the complex interplay of mixed motor types, crowding, kinesin off/on dissociation and reassociation, and injury consequences of forced intermingling. Stalled forward progression with different injury states is seen as persistent dynamicity of kinesins transiting between MTs and inter-MT reservoirs. DyNAMO analysis provides novel insights and quantification of axonal injury scenarios, including local injury-affected ATP levels, as well as relates these to influences on signaling outputs, including patterns of gating, waves, and pattern switching. The DyNAMO model significantly expands the network of heuristic and mathematical analysis of neuronal functions relevant to axonopathies, diagnostics, and treatment strategies.

Project description:UnlabelledDelivery of proteins and organelles to the growth cone during axon extension relies on anterograde transport by kinesin motors. Though critical for neural circuit development, the mechanisms of cargo-specific anterograde transport during axon extension are only starting to be explored. Cargos of particular importance for axon outgrowth are microtubule modifiers, such as SCG10 (Stathmin-2). SCG10 is expressed solely during axon extension, localized to growth cones, and essential for axon outgrowth; however, the mechanisms of SCG10 transport and activity were still debated. Using zebrafish mutants and in vivo imaging, we identified the Kif1B motor and its interactor Kif1 binding protein (KBP) as critical for SCG10 transport to axon growth cones and complete axon extension. Axon truncation in kbp(st23) mutants can be suppressed by SCG10 overexpression, confirming the direct relationship between decreased SCG10 levels and failed axon outgrowth. Live imaging revealed that the reduced levels of SCG10 in kbp(st23) mutant growth cones led to altered microtubule stability, defining the mechanistic basis of axon truncation. Thus, our data reveal a novel role for the Kif1B-KBP complex in the anterograde transport of SCG10, which is necessary for proper microtubule dynamics and subsequent axon extension.Significance statementTogether, our data define the mechanistic underpinnings of failed axon outgrowth with loss of KBP or its associated motor, Kif1B. In addition, we provide conclusive evidence that this defect results from disruption of anterograde transport of SCG10. This is one of the first examples of a motor to be implicated in the essential transport of a discreet cargo necessary for axon extension. In addition, counter to previous in vitro and cell culture results, neither loss of the Kif1B motor nor KBP resulted in inhibition of mitochondrial transport. Altogether, our work links transport of SCG10 to the regulation of microtubule dynamics in the axon growth cone and enhances our understanding of this process during axon outgrowth.

Dataset Information

FIGNL1 associates with KIF1B? and BICD1 to restrict dynein transport velocity during axon navigation.

Publications

FIGNL1 associates with KIF1Bβ and BICD1 to restrict dynein transport velocity during axon navigation.

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