Selection of DNA Aptamer That Blocks the Fibrillogenesis of a Proteolytic Amyloidogenic Fragment of β2m

Abstract Dialysis‐related amyloidosis (DRA) is a severe complication of hemodialysis that results in progressive destruction of bones and joints. Elevated concentrations of the β2‐microglobulin (β2m) level in the serum of subjects on hemodialysis promote the formation of amyloid fibrils in osteoarticular tissues. β2m lacking the N‐terminal six residues of the mature protein (ΔN6β2m) constitutes 25–30% of β2m in ex vivo DRA amyloid. Unlike full‐length wild‐type β2m, ΔN6β2m forms amyloid fibrils at neutral pH in vitro. However, the role of ΔN6β2m in DRA is, at present, poorly understood. In the present study, we screened novel phosphorothioate‐modified aptamers directed against ΔN6β2m using combinatorial chemistry in vitro. We identified 11 ΔN6β2m aptamers; among the identified aptamers, clone #2, #8, and #10 aptamers had higher binding affinity to ΔN6β2m than the others. Biolayer interferometry analysis revealed that KD values of clone #2, #8, and #10 aptamers were 56, 23, and 44 nM, respectively. Furthermore, the clone #8 aptamer inhibited fibril formation in a dose‐dependent manner, as assessed by Thioflavin T fluorescence assay. Fibrils formed from ΔN6β2m bind to Congo red, displaying changes in the absorbance spectrum of the dye characteristic of binding to amyloid fibrils, which was completely blocked by treatment with clone #8 aptamer. These results suggest the potential of ΔN6β2m aptamers as tools for elucidating co‐assembly mecha...
Source: Therapeutic Apheresis and Dialysis - Category: Hematology Authors: Tags: Original Article Source Type: research