Isolation of synaptic terminals from Alzheimer's disease cortex

Authors

  • Sophie Sokolow,

    Corresponding author
    1. UCLA School of Nursing, Los Angeles, California 90095
    2. UCLA Center for the Advancement of Gerontological Nursing Sciences, Los Angeles, California 90095
    3. UCLA Brain Research Institute, Los Angeles, California 90095
    • UCLA School of Nursing, 700 Tiverton Avenue, Factor Bldg #5-946, Los Angeles, CA 90095, USA. Tel.: +1-310-206-3390. Fax: +1-310-206-7703.
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    • Tel.: +1-310-206-3390. Fax: +1-310-206-7703.

  • Kristen M. Henkins,

    1. UCLA Neuroscience Interdepartmental Program, Los Angeles, California 90095
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  • Iris A. Williams,

    1. Department of Hematology & Oncology, David Geffen School of Medicine at UCLA, Los Angeles, California 90095
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  • Harry V. Vinters,

    1. Department of Pathology and Laboratory Medicine and Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California 90095
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  • Ingrid Schmid,

    1. Department of Hematology & Oncology, David Geffen School of Medicine at UCLA, Los Angeles, California 90095
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  • Gregory M. Cole,

    1. Department of Medicine and Neurology, David Geffen School of Medicine at UCLA Los Angeles, Los Angeles, California 90095
    2. Veterans Greater Los Angeles Healthcare System, Geriatric Research Education and Clinical Center, North Hills, California 91343
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  • Karen H. Gylys

    1. UCLA School of Nursing, Los Angeles, California 90095
    2. UCLA Center for the Advancement of Gerontological Nursing Sciences, Los Angeles, California 90095
    3. UCLA Brain Research Institute, Los Angeles, California 90095
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Abstract

Amyloid beta (Aβ) oligomers and phosphorylated tau (p-tau) aggregates are increasingly identified as potential toxic intermediates in Alzheimer's disease (AD). In cortical AD synapses, p-tau co-localizes with Aβ, but the Aβ and p-tau peptide species responsible for synaptic dysfunction and demise remains unclear. The present experiments were designed to use high-speed cell sorting techniques to purify synaptosome population based on size, and then extend the method to physically isolate Aβ-positive synaptosomes with the goal of understanding the nature of Aβ and tau pathology in AD synapses. To examine the purity of size-gated synaptosomes, samples were first gated on size; particles with sizes between 0.5 and 1.5 microns were collected. Electron microscopy documented a homogenous population of spherical particles with internal vesicles and synaptic densities. Next, size-gated synaptosomes positive for Aβ were collected by fluorescence activated sorting and then analyzed by immunoblotting techniques. Sorted Aβ-positive synaptosomes were enriched for amyloid precursor protein (APP) and for Aβ oligomers and aggregates; immunolabeling for p-tau showed a striking accumulation of p-tau aggregates compared to the original homogenate and purified synaptosomes. These results confirm co-localization of Aβ and p-tau within individual synaptic terminals and provide proof of concept for the utility of flow sorting synaptosomes. © 2011 International Society for Advancement of Cytometry

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