Abstract
The axon initial segment (AIS) is a unique neuronal compartment that plays a crucial role in the generation of action potential and neuronal polarity. The assembly of the AIS requires membrane, scaffolding, and cytoskeletal proteins, including Ankyrin-G and TRIM46. How these components cooperate in AIS formation is currently poorly understood. Here, we show that Ankyrin-G acts as a scaffold interacting with End-Binding (EB) proteins and membrane proteins such as Neurofascin-186 to recruit TRIM46-positive microtubules to the plasma membrane. Using in vitro reconstitution and cellular assays, we demonstrate that TRIM46 forms parallel microtubule bundles and stabilizes them by acting as a rescue factor. TRIM46-labeled microtubules drive retrograde transport of Neurofascin-186 to the proximal axon, where Ankyrin-G prevents its endocytosis, resulting in stable accumulation of Neurofascin-186 at the AIS. Neurofascin-186 enrichment in turn reinforces membrane anchoring of Ankyrin-G and subsequent recruitment of TRIM46-decorated microtubules. Our study reveals feedback-based mechanisms driving AIS assembly.
Original language | English |
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Pages (from-to) | 305-321.e8 |
Number of pages | 25 |
Journal | Neuron |
Volume | 104 |
Issue number | 2 |
DOIs | |
Publication status | Published - 23 Oct 2019 |
Externally published | Yes |
Keywords
- Animals
- Ankyrins/metabolism
- Axon Initial Segment/metabolism
- Axonal Transport
- COS Cells
- Cell Adhesion Molecules/metabolism
- Cell Line, Tumor
- Chlorocebus aethiops
- Cytoskeleton
- Endocytosis
- Feedback, Physiological
- HEK293 Cells
- Hippocampus/cytology
- Humans
- Microtubule-Associated Proteins/metabolism
- Microtubules/metabolism
- Nerve Growth Factors/metabolism
- Neurons/metabolism
- Rats
- Tripartite Motif Proteins/metabolism
- GIANT ANKYRIN-G
- CARGO TRANSPORT
- ACTIVITY-DEPENDENT RELOCATION
- LOCALIZATION
- MICROTUBULES
- NEUROFASCIN
- MOTIF
- MAINTENANCE
- NEURONAL POLARITY
- END-BINDING-PROTEIN