An ER-directed gelsolin nanobody targets the first step in amyloid formation in a gelsolin amyloidosis mouse model.

Abstract

Hereditary gelsolin amyloidosis is an autosomal dominantly inherited amyloid disorder. A point mutation in the GSN gene (G654A being the most common one) results in disturbed calcium binding by the second gelsolin domain (G2). As a result, the folding of G2 is hampered, rendering the mutant plasma gelsolin susceptible to a proteolytic cascade. Consecutive cleavage by furin and MT1-MMP-like proteases generates 8 and 5 kDa amyloidogenic peptides that cause neurological, ophthalmological and dermatological findings. To this day, no specific treatment is available to counter the pathogenesis. Using GSN nanobody 11 as a molecular chaperone, we aimed to protect mutant plasma gelsolin from furin proteolysis in the trans-Golgi network. We report a transgenic, GSN nanobody 11 secreting mouse that was used for crossbreeding with gelsolin amyloidosis mice. Insertion of the therapeutic nanobody gene into the gelsolin amyloidosis mouse genome resulted in improved muscle contractility. X-ray crystal structure determination of the gelsolin G2:Nb11 complex revealed that Nb11 does not directly block the furin cleavage site. We conclude that nanobodies can be used to shield substrates from aberrant proteolysis and this approach might establish a novel therapeutic strategy in amyloid diseases.

• Authors: Wouter Van Overbeke, Jantana Wongsantichon, Inge Everaert, Adriaan Verhelle, Olivier Zwaenepoel, Anantasak Loonchanta, Leslie D Burtnick, Ariane De Ganck, Tino Hochepied, Jody Haigh, Claude Cuvelier, Wim Derave, Robert C Robinson, Jan Gettemans
• Journal: Human molecular genetics (Hum Mol Genet) Vol. 24 Issue 9 Pg. 2492-507 (May 01 2015) ISSN: 1460-2083 [Electronic] England
• PMID: 25601851 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: [email protected].

Chemical References

• Amyloid
• Gelsolin
• Single-Domain Antibodies
• Furin

Topics

• Amyloid (metabolism)
• Amyloidosis, Familial (genetics, metabolism, physiopathology)
• Animals
• Disease Models, Animal
• Endoplasmic Reticulum (metabolism)
• Furin (metabolism)
• Gelsolin (antagonists & inhibitors, chemistry, genetics, metabolism)
• Gene Expression
• HEK293 Cells
• Humans
• Mice
• Mice, Transgenic
• Muscle Contraction
• Muscle, Skeletal (metabolism, physiopathology)
• Mutation
• Protein Binding
• Protein Conformation
• Proteolysis (drug effects)
• Single-Domain Antibodies (chemistry, pharmacology)
• trans-Golgi Network (metabolism)