Dynamic imaging of cannabinoid receptor 1 vesicular trafficking in cultured astrocytes

Kyle D. Osborne, William Lee, Erik B. Malarkey, Andrew J. Irving, Vladimir Parpura

    Research output: Contribution to journalArticle

    30 Citations (Scopus)

    Abstract

    Astrocytes possess GPCRs (G-protein-coupled receptors) for neuroactive substances and can respond via these receptors to signals originating from neurons as well as astrocytes. Like many transmembrane proteins, GPCRs exist in a dynamic equilibrium between receptors expressed at the plasma membrane and those present within intracellular trafficking compartments. The characteristics of GPCR trafficking within astrocytes have not been investigated. We therefore monitored the trafficking of recombinant fluorescent protein chimeras of the CB1R (cannabinoid receptor 1) that is thought to be expressed natively in astrocytes. CB1R chimeras displayed a marked punctate intracellular localization when expressed in cultured rat visual cortex astrocytes, an expression pattern reminiscent of native CB1R expression in these cells. Based upon trafficking characteristics, we found the existence of two populations of vesicular CB1R puncta: (i) relatively immobile puncta with movement characteristic of diffusion and (ii) mobile puncta with movement characteristic of active transport along cytoskeletal elements. The predominant direction of active transport is oriented radially to/from the nuclear region, which can be abolished by disruption of the microtubule cytoskeleton. CB1R puncta are localized within intracellular acidic organelles, mainly co-localizing with endocytic compartments. Constitutive trafficking of CB1R to and from the plasma membrane is an energetically costly endeavour whose function is at present unclear in astrocytes. However, given that intracellular CB1Rs can engage cell signalling pathways, it is likely that this process plays an important regulatory role.

    Original languageEnglish
    Article numbere00022
    Pages (from-to)-
    Number of pages14
    JournalASN NEURO
    Volume1
    Issue number5
    Publication statusPublished - 2009

    Keywords

    • actin
    • acutely isolated astrocyte
    • cannabinoid receptor
    • microtubule
    • vesicular trafficking
    • GLUTAMATE RELEASE
    • ULTRASTRUCTURAL-LOCALIZATION
    • VESICLE MOBILITY
    • RAT ASTROCYTES
    • GLIAL-CELLS
    • INTERNALIZATION
    • FLUORESCENT
    • NEURONS
    • PROTEIN
    • ACTIN

    Cite this

    Osborne, K. D., Lee, W., Malarkey, E. B., Irving, A. J., & Parpura, V. (2009). Dynamic imaging of cannabinoid receptor 1 vesicular trafficking in cultured astrocytes. ASN NEURO, 1(5), -. [e00022].
    Osborne, Kyle D. ; Lee, William ; Malarkey, Erik B. ; Irving, Andrew J. ; Parpura, Vladimir. / Dynamic imaging of cannabinoid receptor 1 vesicular trafficking in cultured astrocytes. In: ASN NEURO. 2009 ; Vol. 1, No. 5. pp. -.
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    Osborne, KD, Lee, W, Malarkey, EB, Irving, AJ & Parpura, V 2009, 'Dynamic imaging of cannabinoid receptor 1 vesicular trafficking in cultured astrocytes', ASN NEURO, vol. 1, no. 5, e00022, pp. -.

    Dynamic imaging of cannabinoid receptor 1 vesicular trafficking in cultured astrocytes. / Osborne, Kyle D.; Lee, William; Malarkey, Erik B.; Irving, Andrew J.; Parpura, Vladimir.

    In: ASN NEURO, Vol. 1, No. 5, e00022, 2009, p. -.

    Research output: Contribution to journalArticle

    TY - JOUR

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    AU - Osborne, Kyle D.

    AU - Lee, William

    AU - Malarkey, Erik B.

    AU - Irving, Andrew J.

    AU - Parpura, Vladimir

    PY - 2009

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    N2 - Astrocytes possess GPCRs (G-protein-coupled receptors) for neuroactive substances and can respond via these receptors to signals originating from neurons as well as astrocytes. Like many transmembrane proteins, GPCRs exist in a dynamic equilibrium between receptors expressed at the plasma membrane and those present within intracellular trafficking compartments. The characteristics of GPCR trafficking within astrocytes have not been investigated. We therefore monitored the trafficking of recombinant fluorescent protein chimeras of the CB1R (cannabinoid receptor 1) that is thought to be expressed natively in astrocytes. CB1R chimeras displayed a marked punctate intracellular localization when expressed in cultured rat visual cortex astrocytes, an expression pattern reminiscent of native CB1R expression in these cells. Based upon trafficking characteristics, we found the existence of two populations of vesicular CB1R puncta: (i) relatively immobile puncta with movement characteristic of diffusion and (ii) mobile puncta with movement characteristic of active transport along cytoskeletal elements. The predominant direction of active transport is oriented radially to/from the nuclear region, which can be abolished by disruption of the microtubule cytoskeleton. CB1R puncta are localized within intracellular acidic organelles, mainly co-localizing with endocytic compartments. Constitutive trafficking of CB1R to and from the plasma membrane is an energetically costly endeavour whose function is at present unclear in astrocytes. However, given that intracellular CB1Rs can engage cell signalling pathways, it is likely that this process plays an important regulatory role.

    AB - Astrocytes possess GPCRs (G-protein-coupled receptors) for neuroactive substances and can respond via these receptors to signals originating from neurons as well as astrocytes. Like many transmembrane proteins, GPCRs exist in a dynamic equilibrium between receptors expressed at the plasma membrane and those present within intracellular trafficking compartments. The characteristics of GPCR trafficking within astrocytes have not been investigated. We therefore monitored the trafficking of recombinant fluorescent protein chimeras of the CB1R (cannabinoid receptor 1) that is thought to be expressed natively in astrocytes. CB1R chimeras displayed a marked punctate intracellular localization when expressed in cultured rat visual cortex astrocytes, an expression pattern reminiscent of native CB1R expression in these cells. Based upon trafficking characteristics, we found the existence of two populations of vesicular CB1R puncta: (i) relatively immobile puncta with movement characteristic of diffusion and (ii) mobile puncta with movement characteristic of active transport along cytoskeletal elements. The predominant direction of active transport is oriented radially to/from the nuclear region, which can be abolished by disruption of the microtubule cytoskeleton. CB1R puncta are localized within intracellular acidic organelles, mainly co-localizing with endocytic compartments. Constitutive trafficking of CB1R to and from the plasma membrane is an energetically costly endeavour whose function is at present unclear in astrocytes. However, given that intracellular CB1Rs can engage cell signalling pathways, it is likely that this process plays an important regulatory role.

    KW - actin

    KW - acutely isolated astrocyte

    KW - cannabinoid receptor

    KW - microtubule

    KW - vesicular trafficking

    KW - GLUTAMATE RELEASE

    KW - ULTRASTRUCTURAL-LOCALIZATION

    KW - VESICLE MOBILITY

    KW - RAT ASTROCYTES

    KW - GLIAL-CELLS

    KW - INTERNALIZATION

    KW - FLUORESCENT

    KW - NEURONS

    KW - PROTEIN

    KW - ACTIN

    M3 - Article

    VL - 1

    SP - -

    JO - ASN NEURO

    JF - ASN NEURO

    SN - 1759-0914

    IS - 5

    M1 - e00022

    ER -

    Osborne KD, Lee W, Malarkey EB, Irving AJ, Parpura V. Dynamic imaging of cannabinoid receptor 1 vesicular trafficking in cultured astrocytes. ASN NEURO. 2009;1(5):-. e00022.