European Biophysics Journal

, Volume 39, Issue 9, pp 1281–1288

Comparison of aggregation enhancement and inhibition as strategies for reducing the cytotoxicity of the aortic amyloid polypeptide medin

Original Paper

DOI: 10.1007/s00249-010-0581-3

Cite this article as:
Madine, J. & Middleton, D.A. Eur Biophys J (2010) 39: 1281. doi:10.1007/s00249-010-0581-3

Abstract

Aortic medial amyloid (AMA) occurs as localised non-atheromatous plaques in virtually all individuals over the age of 50. The major protein component of AMA is the 50-residue polypeptide medin. Here we propose two methods of manipulating medin aggregation to reduce the cytotoxic species of medin: either by promoting formation of larger benign species or retaining small non-cytotoxic species. Medin co-localises with a variety of factors including glycosaminoglycans (GAGs). The first approach shows that the GAG heparin enhances the rate of medin aggregation and alters the morphology of the amyloid fibrils. Cellular viability measurements suggest that heparin eliminates small cytotoxic species of medin, promoting formation of benign fibrils. The second approach applies a previously successful approach of designing small peptide moieties that are complementary to the key amyloidogenic sequence but which contain modified amino acids known to disrupt hydrogen bonding and therefore prevent aggregation of the target protein. This approach also reduces cellular toxicity of medin at all stages of the aggregation process examined exhibiting a different mode of action to heparin. These results raise the question of whether enhancement of medin aggregation by GAGs is beneficial, by eliminating toxic oligomers, or has deleterious effects by reducing arterial plasticity associated with increased fibril load and whether small peptide inhibitors can be applied as drug candidates for amyloid diseases.

Keywords

MedinGlycosaminoglycansInhibitorCytotoxicityAmyloid

Abbreviations

AMed42–49

Peptide corresponding to residues 42–49 of medin

AMA

Aortic medial amyloid

BA

β-Alanine

DLS

Dynamic light scattering

GABA

γ-Aminobutyric acid

GAG

Glycosaminoglycan

HSPG

Heparin sulphate proteoglycan

MTT

(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide

TEM

Transmission electron microscopy

ThT

Thioflavin T

SRE

Self-recognition element

Copyright information

© European Biophysical Societies' Association 2010

Authors and Affiliations

  1. 1.School of Biological SciencesUniversity of LiverpoolLiverpoolUK