Aggregation of wild‐type gelsolin peptides and mutants and inhibition

Abstract

Gelsolin amyloidosis is a disease characterized by several point mutations that lead to cleavage and fibrillization of gelsolin. The D187 mutation to N or Y leads to aggregation of peptide fragments with shortest aggregating peptide identified as 182SFNNGDCFILD192. Recently, G167 has also been identified as relevant gelsolin mutation, which leads to gelsolin deposits in kidneys but its aggregation is much less understood. Hence, we systematically investigated in vitro the aggregation propensities of the following gelsolin peptides: 167GRRVV171, 161RLFQVKG167, 184NNGDCFILDL193, 188CFILDL193, 187DCFILDL193, and their respective mutants (G167K, G167R, N184K, D187Y, D187N), by using spectroscopic methods (fluorescence proteostat, Thioflavin T (ThT), turbidity assay, and Dynamic Light Scattering (DLS)), and Transmission Electron Microscopy (TEM). The (non) mutant peptides containing CFILDL sequence aggregated into fibrillar networks, while G167R mutation promoted aggregation compared to the wild‐type sequence. In the presence of inhibitors, Methylene Blue (MB) and Epigallocatechin gallate (EGCG), the gelsolin peptide aggregation was reduced. We discovered that inhibitors have dual functionality, as aggregation inhibitors and disaggregation promoters, potentially allowing for the prevention and reversal of gelsolin amyloidosis. Such therapeutic strategies may significantly improve outcomes related to other amyloidogenic diseases of the heart, brain and eye.