Selection of Membrane RNA Aptamers to Amyloid Beta Peptide: Implications for Exosome-Based Antioxidant Strategies

Abstract

The distribution of amyloid beta peptide 42 (Aβ42) between model exosomal membranes and a buffer solution was measured. The model membranes contained liquid-ordered regions or phosphatidylserine. Results demonstrated that up to ca. 20% of amyloid peptide, generated in the plasma (or intracellular) membrane as a result of proteolytic cleavage of amyloid precursor proteins by β- and γ-secretases, can stay within the membrane milieu. The selection of RNA aptamers that bind to Aβ42 incorporated into phosphatidylserine-containing liposomal membranes was performed using the selection-amplification (SELEX) method. After eight selection cycles, the pool of RNA aptamers was isolated and its binding to Aβ42-containing membranes was demonstrated using the gel filtration method. Since membranes can act as a catalytic surface for Aβ42 aggregation, these RNA aptamers may inhibit the formation of toxic amyloid aggregates that can permeabilize cellular membranes or disrupt membrane receptors. Strategies are proposed for using functional exosomes, loaded with RNA aptamers specific to membrane Aβ42, to reduce the oxidative stress in Alzheimer’s disease and Down’s syndrome.

Binding of RNA Aptamers to Membrane Lipid Rafts: Implications for Exosomal miRNAs Transfer from Cancer to Immune Cells

“…A passive membrane transporter specifically directed to the amino acid tryptophan was constructed and characterized, by combining preselected RNA–lipid bilayer affinity domains with an RNA amino acid binding site [ 13 ]. Membrane RNA aptamers that bind to amyloid protein incorporated into liposomal membrane have been selected using the selection-amplification (SELEX) method [ 14 ]. Binding of bona fide cellular RNAs under physiological ionic conditions to membranes has been shown for the first time in the case of human tRNA Sec [ 15 ].…”

Cholera Toxin Subunit B for Sensitive and Rapid Determination of Exosomes by Gel Filtration

“…In order to separate CTB-labeled exosomes (or liposomes) from free (unbound) CTB, gel filtration assay was used. Gel filtration assay was performed as described [ 15 ]. Briefly, 40 μL of exosomes (or liposomes) were incubated with CTB555 (80 nM) for 1 h at 37 °C, then applied to 1 mL S-1000 column and eluted with PBS.…”

Updates on Aptamer Research

“…For example, aptamers that were selected against monomeric/oligomeric forms of amyloid peptide had very low affinity to these forms, although they exhibited a strong non-specific affinity to amyloid high-molecular weight fibrils [137,138]. It is thought, however, that aptamers still hold promise for the treatment of Alzheimer’s disease because current amyloid inhibitors and antibodies are not effective at the membrane surface, where inhibition of amyloid aggregate and channel formation is needed to stop disease progression [139]. Janas et al 2019 shows that functional exosomes containing the selected pool of aptamers can inhibit the formation of amyloid aggregates and channel activity at the membrane surface [139].…”

“…It is thought, however, that aptamers still hold promise for the treatment of Alzheimer’s disease because current amyloid inhibitors and antibodies are not effective at the membrane surface, where inhibition of amyloid aggregate and channel formation is needed to stop disease progression [139]. Janas et al 2019 shows that functional exosomes containing the selected pool of aptamers can inhibit the formation of amyloid aggregates and channel activity at the membrane surface [139].…”