TY - JOUR

T1 - Comparison of aggregation enhancement and inhibition as strategies for reducing the cytotoxicity of the aortic amyloid polypeptide medin

AU - Madine, Jillian

AU - Middleton, David A

PY - 2010/8

Y1 - 2010/8

N2 - 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.

AB - 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.

KW - Amyloid

KW - Animals

KW - Aorta

KW - Cattle

KW - Cell Line

KW - Cell Survival

KW - Endothelial Cells

KW - Heparin

KW - Peptide Fragments

KW - Protein Multimerization

KW - Protein Structure, Quaternary

U2 - 10.1007/s00249-010-0581-3

DO - 10.1007/s00249-010-0581-3

M3 - Journal article

C2 - 20162269

VL - 39

SP - 1281

EP - 1288

JO - June 2002. ISSN 1460-4582

JF - June 2002. ISSN 1460-4582

SN - 0893-3200

IS - 9

ER -