A novel mechano-enzymatic cleavage mechanism underlies transthyretin amyloidogenesis.
The mechanisms underlying transthyretin-related amyloidosis in vivo remain unclear. The abundance of the 49-127 transthyretin fragment in ex vivo deposits suggests that a proteolytic cleavage has a crucial role in destabilizing the tetramer and releasing the highly amyloidogenic 49-127 truncated protomer. Here, we investigate the mechanism of cleavage and release of the 49-127 fragment from the prototypic S52P variant, and we show that the proteolysis/fibrillogenesis pathway is common to several amyloidogenic variants of transthyretin and requires the action of biomechanical forces provided by the shear stress of physiological fluid flow. Crucially, the non-amyloidogenic and protective T119M variant is neither cleaved nor generates fibrils under these conditions. We propose that a mechano-enzymatic mechanism mediates transthyretin amyloid fibrillogenesis in vivo. This may be particularly important in the heart where shear stress is greatest; indeed, the 49-127 transthyretin fragment is particularly abundant in cardiac amyloid. Finally, we show that existing transthyretin stabilizers, including tafamidis, inhibit proteolysis-mediated transthyretin fibrillogenesis with different efficiency in different variants; however, inhibition is complete only when both binding sites are occupied.
Department of Chemistry, University of Oxford, Oxford, UK Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), University of Strasbourg UDS, Strasbourg, France.
Julien
J
Marcoux
Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, London, UK Department of Molecular Medicine, Institute of Biochemistry, University of Pavia, Pavia, Italy.
P Patrizia
PP
Mangione
Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, London, UK.
Riccardo
R
Porcari
Department of Chemistry, University of Oxford, Oxford, UK.
Matteo T
MT
Degiacomi
Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, London, UK Department of Molecular Medicine, Institute of Biochemistry, University of Pavia, Pavia, Italy.
Guglielmo
G
Verona
Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, London, UK.
Graham W
GW
Taylor
Department of Molecular Medicine, Institute of Biochemistry, University of Pavia, Pavia, Italy.
Sofia
S
Giorgetti
Department of Molecular Medicine, Institute of Biochemistry, University of Pavia, Pavia, Italy.
Sara
S
Raimondi
Laboratoire de Spectrométrie de Masse BioOrganique (LSMBO), University of Strasbourg UDS, Strasbourg, France.
Sarah
S
Sanglier-Cianférani
Department of Chemistry, University of Oxford, Oxford, UK.
Justin L P
JL
Benesch
Institute of Nanoscience S3, Consiglio Nazionale delle Ricerche, Modena, Italy Department of Physics, Informatics and Mathematics, University of Modena and Reggio Emilia, Modena, Italy.
Ciro
C
Cecconi
Department of Physics, Informatics and Mathematics, University of Modena and Reggio Emilia, Modena, Italy.
Mohsin M
MM
Naqvi
Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, London, UK.
Julian D
JD
Gillmore
Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, London, UK.
Philip N
PN
Hawkins
Department of Molecular Medicine, Institute of Biochemistry, University of Pavia, Pavia, Italy.
Monica
M
Stoppini
Department of Chemistry, University of Oxford, Oxford, UK.
Carol V
CV
Robinson
Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, London, UK.
Mark B
MB
Pepys
Wolfson Drug Discovery Unit, Centre for Amyloidosis and Acute Phase Proteins, Division of Medicine, University College London, London, UK Department of Molecular Medicine, Institute of Biochemistry, University of Pavia, Pavia, Italy v.bellotti@ucl.ac.uk.
Vittorio
V
Bellotti
D028227:Amyloid Neuropathies, Familial / Q000209:etiology / Q000378:metabolism*; D006801:Humans; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011228:Prealbumin / Q000737:chemistry / Q000378:metabolism; D059748:Proteolysis
D010446:Peptide Fragments; D011228:Prealbumin
amyloid; mechano‐enzymatic cleavage; transthyretin