Abstract
The receptor for advanced glycation end products (RAGE) is a signal receptor first shown to be activated by advanced glycation end products, but also by a variety of signal molecules, including pathological advanced oxidation protein products and β‐amyloid. However, most of the RAGE activators have multiple intracellular targets, making it difficult to unravel the exact pathway of RAGE activation. Here, we show that the cell‐impermeable RAGE fragment sequence (60–76) of the V‐domain of the receptor is able to activate RAGE present on the plasma membrane of neurons and, preferentially, astrocytes. This leads to the exocytosis of vesicular glutamate transporter vesicles and the release of glutamate from astrocytes, which stimulate NMDA and AMPA/kainate receptors, resulting in calcium signals predominantly in neurons. Thus, we show a specific mechanism of RAGE activation by the RAGE fragment and propose a mechanism by which RAGE activation can contribute to the neuronal‐astrocytic communication in physiology and pathology.
Highlights
The receptor for advanced glycation end products (RAGE) is a signal transduction receptor in the form of a transmembrane protein that belongs to the immunoglobulin superfamily
We have found that the RAGE fragment induces calcium signals in neurons through the activation of RAGE on the membrane of astrocytes, which leads to the release of glutamate from vesicular glutamate transporter (VGLUT) vesicles and activates glutamate‐induced calcium signal in neurons
To prove that the fusion of VGLUT2 vesicles in astrocytes induced by RAGE activation leads to the release of glutamate, neurons and astrocytes were transfected with the intensity‐based glutamate sensor iGluSnFR and coloaded with the calcium indicator X‐rhod‐1 before the experiments
Summary
The receptor for advanced glycation end products (RAGE) is a signal transduction receptor in the form of a transmembrane protein that belongs to the immunoglobulin superfamily. Expression of RAGE has been described in neurons, astrocytes, and microglia from different brain areas. We have shown that various short RAGE fragments could protect primary cultures of neurons and astrocytes against β‐amyloid toxicity by binding β‐amyloid (Kamynina et al, 2018). Two milliliters of rabbit blood sera containing antibodies against the peptide (60–76) was applied into the column poured with 5 ml of the Sepharose conjugated with Lys2‐peptide. Live primary cocultures of neurons and astrocytes were incubated for 40 min at 4°C with the anti‐RAGE mouse monoclonal antibody (1:100 in HEPES‐buffered salt solution [HBSS]), washed, and fixed for 15 min with 4% PFA. Mixed cultures of hippocampal and cortical neurons and glial cells were prepared as described previously (Vaarmann et al, 2010) with modifications from Sprague‐Dawley rat pups 2–4 days postpartum (UCL breeding colony). The fura‐2 data has not been calibrated in terms of [Ca2+]c because of uncertainty arising from the use of different calibration techniques
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