Cited by 2,632Chemokine receptors and signalingNeuroinflammation and Neurodegeneration MechanismsCell Adhesion Molecules Research

Analysis of Fractalkine Receptor CX3CR1 Function by Targeted Deletion and Green Fluorescent Protein Reporter Gene Insertion

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Jung, Steffen, Aliberti, Julio, Graemmel, Petra, Sunshine, Mary Jean, Kreutzberg, Georg W., Sher, Alan, Littman, Dan R.·2000·Molecular and Cellular Biology

Abstract

The seven-transmembrane receptor CX(3)CR1 is a specific receptor for the novel CX(3)C chemokine fractalkine (FKN) (neurotactin). In vitro data suggest that membrane anchoring of FKN, and the existence of a shed, soluble FKN isoform allow for both adhesive and chemoattractive properties. Expression on activated endothelium and neurons defines FKN as a potential target for therapeutic intervention in inflammatory conditions, particularly central nervous system diseases. To investigate the physiological function of CX(3)CR1-FKN interactions, we generated a mouse strain in which the CX(3)CR1 gene was replaced by a green fluorescent protein (GFP) reporter gene. In addition to the creation of a mutant CX(3)CR1 locus, this approach enabled us to assign murine CX(3)CR1 expression to monocytes, subsets of NK and dendritic cells, and the brain microglia. Analysis of CX(3)CR1-deficient mice indicates that CX(3)CR1 is the only murine FKN receptor. Yet, defying anticipated FKN functions, absence of CX(3)CR1 interferes neither with monocyte extravasation in a peritonitis model nor with DC migration and differentiation in response to microbial antigens or contact sensitizers. Furthermore, a prominent response of CX(3)CR1-deficient microglia to peripheral nerve injury indicates unimpaired neuronal-glial cross talk in the absence of CX(3)CR1.

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Crossref · 10.1128/mcb.20.11.4106-4114.2000

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  • Cx3cr1-CreERT2 developed by Jung et al. (2000) was reported to drive microglia-specific expression.

    “Cx3cr1-CreERT2 developed by Jung et al. (2000) was reported to drive microglia-specific expression.”

    From Targeting Microglia Using Cx3cr1-Cre Lines: Revisiting the Specificity (2019) · cites this paper as Jung et al. (2000)

    The Results and Discussion describe a CX3CR1-GFP reporter mouse, not a Cx3cr1-CreERT2 mouse. Although GFP was observed in microglia, the same section reports expression in peripheral blood monocytes and subsets of NK and dendritic cells, contrary to microglia-specific expression. (LLM, conf=0.90)

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  • This basal cre activity in the Cx3cr1-CreERT2 line developed by Jung et al. (2000) was restricted to microglia.

    “The inducible Cx3cr1-CreERT2 line developed by Jung et al. (2000), displayed some basal cre activity without tamoxifen treatment, but this expression was restricted to microglia.”

    From Targeting Microglia Using Cx3cr1-Cre Lines: Revisiting the Specificity (2019) · cites this paper as Jung et al. (2000)

    The Results and Discussion describe a CX3CR1-GFP reporter mouse, not an inducible Cx3cr1-CreERT2 line. Materials and Methods say Cre was used transiently in embryonic stem cells to remove a selection cassette; the paper does not report basal Cre activity or tamoxifen treatment. Its GFP expression was also observed in peripheral blood monocytes, not only microglia. (LLM, conf=0.90)

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  • The inducible Cx3cr1-CreERT2 line developed by Jung et al. (2000) displayed some basal cre activity without tamoxifen treatment.

    “The inducible Cx3cr1-CreERT2 line developed by Jung et al. (2000), displayed some basal cre activity without tamoxifen treatment, but this expression was restricted to microglia.”

    From Targeting Microglia Using Cx3cr1-Cre Lines: Revisiting the Specificity (2019) · cites this paper as Jung et al. (2000)

    The Results and Discussion describe a CX3CR1–GFP knock-in mouse, not an inducible Cx3cr1-CreERT2 line. Materials and Methods say Cre was introduced transiently into embryonic stem cells to remove a selection gene; the paper does not report basal Cre activity or tamoxifen treatment. (LLM, conf=0.90)

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  • According to The Jackson Laboratory website, the constitutive Cx3cr1-Cre line created by Jung et al. (2000) displays leakiness into neurons when crossed with a yellow fluorescent protein (YFP) reporter line.

    “According to the description on The Jackson Laboratory website, the constitutive Cx3cr1-Cre line created by Jung et al. (2000), displays leakiness into neurons when crossed with a yellow fluorescent protein (YFP) reporter line.”

    From Targeting Microglia Using Cx3cr1-Cre Lines: Revisiting the Specificity (2019) · cites this paper as Jung et al. (2000)

    The Results and Discussion section (‘Generation of CX3CR-1GFP mice’; page not provided) says Jung et al. generated a CX3CR1–EGFP replacement line, not a constitutive Cx3cr1-Cre line. The Methods say Cre was used transiently in embryonic stem cells to remove the neo gene. The paper does not report a YFP-reporter cross or neuronal leakiness. (LLM, conf=0.88)

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  • The cre activity in the Cx3cr1-CreERT2 line developed by Jung et al. (2000) is not fully dependent on tamoxifen.

    “Thus, the cre activity in this line is not fully dependent on tamoxifen.”

    From Targeting Microglia Using Cx3cr1-Cre Lines: Revisiting the Specificity (2019) · cites this paper as Jung et al. (2000)

    The Results and Discussion (page not available) identify the line Jung et al. generated as CX3CR1-GFP, with EGFP replacing part of the CX3CR1 gene—not a Cx3cr1-CreERT2 line. Materials and Methods (page not available) mention Cre only as a vector transiently introduced into embryonic stem cells to remove a selection gene. The paper does not assess tamoxifen dependence. (LLM, conf=0.86)

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Authors
Jung, S., Aliberti, J., Graemmel, P., Sunshine, M. J., Kreutzberg, G. W., Sher, A., & Littman, D. R.
Affiliations
  • Howard Hughes Medical Institute (US)
  • Immunobiology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
  • Max Planck Institute of Neurobiology (DE)
  • National Institutes of Health (US)
Corresponding author
Jung, Steffen
Venue
Molecular and Cellular Biology
Published
2000-06-01
Volume
20
Issue
11
Pages
4106-4114
ISSN
  • 0270-7306 (ISSN-L)
  • 1098-5549
OpenAlex
W2161057248
Cited by
2,632
References
20
Citations by year
2026: 87 · 2025: 132 · 2024: 172 · 2023: 138 · 2022: 135 · 2021: 192 · 2020: 174 · 2019: 162 · 2018: 136 · 2017: 147 · 2016: 142 · 2015: 140 · 2014: 163 · 2013: 128 · 2012: 95
FWCI
11.19
Type
journal article
Language
en
Open access
Locations
  • Molecular and Cellular Biology (publishedVersion)
  • Europe PMC (PubMed Central) (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
Howard Hughes Medical Institute
Topics
  • Health Sciences › Medicine › Oncology › Chemokine receptors and signaling
  • Life Sciences › Neuroscience › Neurology › Neuroinflammation and Neurodegeneration Mechanisms
  • Health Sciences › Medicine › Immunology and Allergy › Cell Adhesion Molecules Research
Keywords
CX3CR1, fractalkine, CX3C chemokines, G protein-coupled receptors, monocytes, dendritic cells, natural killer cells, microglia, monocyte extravasation, peritonitis, dendritic cell migration, peripheral nerve injury, neuroinflammation
MeSH terms
CX3C Chemokine Receptor 1, Animals, Luminescent Proteins, Mice, Mutant Strains, Phenotype, Receptors, HIV, Gene Expression, Mutagenesis, Insertional, Genes, Reporter, Receptors, Cytokine, Gene Targeting, Green Fluorescent Proteins, Mice

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