Cited by 44Cellular transport and secretionNeuroscience and Neuropharmacology ResearchNerve injury and regeneration

The DOI matches its Crossref record; 45 of the 45 references it cites were found in a registry or an index; 1 of the 34 sources its claims cite were checked for support.

Alterations of EHD1/EHD4 Protein Levels Interfere with L1/NgCAM Endocytosis in Neurons and Disrupt Axonal Targeting

Open access

Abstract

Axon growth is regulated by many proteins, including adhesion molecules, which need to be trafficked correctly to axons. The adhesion molecule L1/neuron–glia cell adhesion molecule (NgCAM) travels to axons via an endocytosis-dependent pathway (transcytosis), traversing somatodendritic endosomes. The Eps15 homology domain (EHD) family proteins (EHD1–EHD4) play important roles in endosomal recycling and possibly in endocytosis. We investigated whether EHD1 regulates L1/NgCAM trafficking in neurons. Both short hairpin-mediated downregulation and overexpression of EHD1 led to dendritic mistargeting of NgCAM. Downregulation of EHD1 showed increased endosomal accumulation of NgCAM, whereas, surprisingly, overexpression of EHD1 led to impairment of L1/NgCAM internalization in neurons but not in fibroblasts. Transferrin internalization, however, was unaffected. At longer overexpression times of EHD1, NgCAM endocytosis returned to normal, suggesting rapid upregulation of compensatory endocytic pathways. EHD1 is capable of hetero-oligomerization, and an endogenous complex of EHD1 and EHD4 was identified previously. We therefore tested whether short-term overexpression of other EHD family members showed a similar endocytosis defect. Expression of EHD4, but not of EHD3, also caused a defect in L1/NgCAM endocytosis. Oligomerization of EHD1 was required to cause NgCAM endocytosis defects, and simultaneous expression of EHD1 and EHD4 rescued NgCAM endocytosis. Therefore, balanced levels of EHD1–EHD4 are important for NgCAM endocytosis in neurons. Our data suggest that EHD1 plays roles in both endosomal recycling and a specialized endocytosis pathway in neurons used by NgCAM. We propose that EHD1 and EHD4 act as hetero-oligomeric complexes in this pathway.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

EHD1 and EHD4 levels are dosage-sensitive regulators of L1/NgCAM endocytosis in neurons, and altering either protein disrupts NgCAM axonal targeting. The data support a model in which EHD1/EHD4 hetero-oligomers, with balanced stoichiometry, act in a neuron-specific endocytosis pathway for NgCAM.

Key findings

  • Overexpression of wild-type EHD1 or dominant-negative EHD1G429R reduced NgCAM axonal polarity; control neurons showed NgCAM 5–6-fold enriched on axons versus dendrites, while EHD1/EHD1G429R co-expression decreased the axon/dendrite polarity index.
  • EHD1 knockdown increased dendritic surface NgCAM: control dendrite intensity was 756 AFU ± 35 SEM, versus 1233 AFU ± 44 SEM for shEHD1#1 (p<0.0001) and 921 AFU ± 35 SEM for shEHD1#2 (p<0.05).
  • EHD1 or EHD1G429R overexpression impaired NgCAM endocytosis in neurons, but not in COS or NRK cells; transferrin internalization was unaffected, although EHD1G429R slowed transferrin recycling.
  • EHD4 overexpression, but not EHD3, impaired NgCAM endocytosis and reduced NgCAM axonal polarity; endogenous L1 endocytosis in neurons was inhibited by EHD4 after 1 day (43% of control) but not after 3 days (94% of control).
  • Oligomerization-defective EHD1V203P did not impair NgCAM endocytosis or polarity, and co-expression of EHD1 with EHD4 rescued NgCAM endocytosis and axonal polarity (A/D PI 5.0 ± 0.20 in EHD1+EHD4 cells versus 5.5 ± 0.25 in GFP controls).

Methods

  • Primary embryonic day 18 rat hippocampal neurons were cultured and transfected at DIV 9–12 or nucleofected before plating; COS, NRK, and PC12 cells were also used.
  • NgCAM/L1 endocytosis was measured with an acid-strip antibody uptake assay, and surface polarity was quantified as an axon/dendrite polarity index from fluorescence intensities.
  • Quantification used 15–20 cells per condition for polarity/endosomal NgCAM and 150–200 cells per condition for percentage of endocytosing cells, across at least three experiments, with statistical testing in SPSS.

Limitations

  • The paper states that an indirect effect of EHD1/EHD4 overexpression on NgCAM endocytosis cannot be completely ruled out, and that technical constraints prevented testing endogenous L1 endocytosis in more mature cultures.
  • The paper notes that the anti-EHD1 antibody recognized multiple EHD family members on Western blots, that specific anti-EHD1/EHD4 antibodies showed only faint neuronal staining, and that the significance of neuronal nuclear EHD staining is unknown.
  • Evident from the text: EHD1 knockdown achieved only 40–60% reduction, overexpression and knockdown produced distinct phenotypes, and compensatory endocytic pathways restored NgCAM/L1 endocytosis after 3–4 days, so acute versus long-term effects differ.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1523/jneurosci.5428-09.2010

Cites

45 of 45 references verified0 citation errors · 0 not checkable

Statistics

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Verification

Claims the paper makes

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  • Probably not a substantial claim. 26
  • It may state two separate claims as one. 39
58 of 58
  • The paper relies on this without support.

    EHD1 and EHD4 form an endogenous hetero-oligomeric complex (or EHD1 is capable of hetero-oligomerization and an endogenous complex of EHD1 and EHD4 exists).

    “EHD1 is capable of hetero-oligomerization, and an endogenous complex of EHD1 and EHD4 was identified previously.”
  • The paper relies on this without support.

    The shRNA-mediated downregulation of EHD1 is specific to EHD1 and does not affect other EHD family members (EHD2, EHD3) in neurons.

    “To specifically knockdown the EHD1 protein expression, we used short hairpin RNA targeting the rat EHD1 sequences obtained from Super Array Bioscience.”
  • The paper relies on this without support.

    The distribution of EHD proteins has not been investigated in neurons.

    “The distribution of EHD proteins for both endogenous and exogenous protein has been characterized in several non-neuronal cell types (for examples see (Blume et al., 2007; George et al., 2007), but has not been investigated in neurons.”
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Metadata

Authors
Yap, C. C. C., Lasiecka, Z. M., Caplan, S., & Winckler, B.
Affiliations
  • University of Virginia (US)
  • University of Nebraska Medical Center (US)
Corresponding author
Winckler, Bettina
Venue
The Journal of Neuroscience
Published
2010-05-12
Volume
30
Issue
19
Pages
6646-6657
ISSN
  • 0270-6474 (ISSN-L)
  • 1529-2401
OpenAlex
W1978427724
Cited by
44
References
45
Citations by year
2026: 1 · 2025: 2 · 2024: 1 · 2022: 1 · 2020: 3 · 2018: 1 · 2017: 1 · 2016: 7 · 2015: 5 · 2014: 1 · 2013: 3 · 2012: 6
FWCI
1.96
Type
journal article
Language
en
Open access
Locations
  • Journal of Neuroscience (publishedVersion, cc-by-nc-sa)
  • Europe PMC (PubMed Central) (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • National Institutes of Health
  • National Institute of General Medical Sciences (R01GM074876, R01GM086913)
  • National Center for Research Resources (P20RR018759)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Cellular transport and secretion
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neuroscience and Neuropharmacology Research
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Nerve injury and regeneration
Keywords
EHD1, EHD4, endocytosis, axon targeting, transcytosis, endosomal recycling, hetero-oligomerization, axon growth, neurons, transferrin internalization
MeSH terms
Animals, Axons, Cells, Cultured, Chlorocebus aethiops, Endocytosis, Fibroblasts, Hippocampus, Nerve Tissue Proteins, Neurons, Endosomes, Time Factors, Transferrin, Signal Transduction, PC12 Cells, COS Cells, Vesicular Transport Proteins, Neural Cell Adhesion Molecule L1, Cell Enlargement, Rats

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