Neurofascin and Kv7.3 are delivered to somatic and axon terminal surface membranes en route to the axon initial segment
Abstract
Ion channel complexes promote action potential initiation at the mammalian axon initial segment (AIS), and modulation of AIS size by recruitment or loss of proteins can influence neuron excitability. Although endocytosis contributes to AIS turnover, how membrane proteins traffic to this proximal axonal domain is incompletely understood. Neurofascin186 (Nfasc186) has an essential role in stabilising the AIS complex to the proximal axon, and the AIS channel protein Kv7.3 regulates neuron excitability. Therefore, we have studied how these proteins reach the AIS. Vesicles transport Nfasc186 to the soma and axon terminal where they fuse with the neuronal plasma membrane. Nfasc186 is highly mobile after insertion in the axonal membrane and diffuses bidirectionally until immobilized at the AIS through its interaction with AnkyrinG. Kv7.3 is similarly recruited to the AIS. This study reveals how key proteins are delivered to the AIS and thereby how they may contribute to its functional plasticity.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting files.
Article and author information
Author details
Funding
Wellcome (107008)
- Aniket Ghosh
- Elise LV Malavasi
- Diane L Sherman
- Peter J Brophy
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Moses V Chao, New York University Langone Medical Center, United States
Ethics
Animal experimentation: All animal work was performed according to UK legislation (Scientific Procedures) Act 1986 according to the guidelines of and approved by the University of Edinburgh Animal Welfare and Ethical Review Body. All work was performed under a Project Licence (No. P0F4A25E9 issued by the UK Home Office to Peter Brophy and this licence is in force until 26 March, 2022.
Version history
- Received: July 1, 2020
- Accepted: September 8, 2020
- Accepted Manuscript published: September 9, 2020 (version 1)
- Version of Record published: September 23, 2020 (version 2)
Copyright
© 2020, Ghosh et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 1,744
- views
-
- 266
- downloads
-
- 12
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
Further reading
-
- Neuroscience
The central tendency bias, or contraction bias, is a phenomenon where the judgment of the magnitude of items held in working memory appears to be biased toward the average of past observations. It is assumed to be an optimal strategy by the brain and commonly thought of as an expression of the brain’s ability to learn the statistical structure of sensory input. On the other hand, recency biases such as serial dependence are also commonly observed and are thought to reflect the content of working memory. Recent results from an auditory delayed comparison task in rats suggest that both biases may be more related than previously thought: when the posterior parietal cortex (PPC) was silenced, both short-term and contraction biases were reduced. By proposing a model of the circuit that may be involved in generating the behavior, we show that a volatile working memory content susceptible to shifting to the past sensory experience – producing short-term sensory history biases – naturally leads to contraction bias. The errors, occurring at the level of individual trials, are sampled from the full distribution of the stimuli and are not due to a gradual shift of the memory toward the sensory distribution’s mean. Our results are consistent with a broad set of behavioral findings and provide predictions of performance across different stimulus distributions and timings, delay intervals, as well as neuronal dynamics in putative working memory areas. Finally, we validate our model by performing a set of human psychophysics experiments of an auditory parametric working memory task.
-
- Neuroscience
The brain regulates food intake in response to internal energy demands and food availability. However, can internal energy storage influence the type of memory that is formed? We show that the duration of starvation determines whether Drosophila melanogaster forms appetitive short-term or longer-lasting intermediate memories. The internal glycogen storage in the muscles and adipose tissue influences how intensely sucrose-associated information is stored. Insulin-like signaling in octopaminergic reward neurons integrates internal energy storage into memory formation. Octopamine, in turn, suppresses the formation of long-term memory. Octopamine is not required for short-term memory because octopamine-deficient mutants can form appetitive short-term memory for sucrose and to other nutrients depending on the internal energy status. The reduced positive reinforcing effect of sucrose at high internal glycogen levels, combined with the increased stability of food-related memories due to prolonged periods of starvation, could lead to increased food intake.