Association of clusterin with the BRI2-derived amyloid molecules ABri and ADan

Agueda Rostagno,Miguel Calero,Janice L Holton,Tamas Revesz,Tammaryn Lashley,Jorge Ghiso

doi:10.1016/j.nbd.2021.105452

Abstract

Familial British and Danish dementias (FBD and FDD) share striking neuropathological similarities with Alzheimer's disease (AD), including intraneuronal neurofibrillary tangles as well as parenchymal and vascular amyloid deposits. Multiple amyloid associated proteins with still controversial role in amyloidogenesis colocalize with the structurally different amyloid peptides ABri in FBD, ADan in FDD, and Aβ in AD. Genetic variants and plasma levels of one of these associated proteins, clusterin, have been identified as risk factors for AD. Clusterin is known to bind soluble Aβ in biological fluids, facilitate its brain clearance, and prevent its aggregation. The current work identifies clusterin as the major ABri- and ADan-binding protein and provides insight into the biochemical mechanisms leading to the association of clusterin with ABri and ADan deposits. Mirroring findings in AD, the studies corroborate clusterin co-localization with cerebral parenchymal and vascular amyloid deposits in both disorders. Ligand affinity chromatography with downstream Western blot and amino acid sequence analyses unequivocally identified clusterin as the major ABri- and ADan-binding plasma protein. ELISA highlighted a specific saturable binding of clusterin to ABri and ADan with low nanomolar Kd values within the same range as those previously demonstrated for the clusterin-Aβ interaction. Consistent with its chaperone activity, thioflavin T binding assays clearly showed a modulatory effect of clusterin on ABri and ADan aggregation/fibrillization properties. Our findings, together with the known multifunctional activity of clusterin and its modulatory activity on the complex cellular pathways leading to oxidative stress, mitochondrial dysfunction, and the induction of cell death mechanisms – all known pathogenic features of these protein folding disorders – suggests the likelihood of a more complex role and a translational potential for the apolipoprotein in the amelioration/prevention of these pathogenic mechanisms.

Highlights

Clusterin, known as apolipoprotein J (ApoJ), is a ubiquitous protein present in most body fluids (Calero et al, 2005; Calero et al, 2000) and the most highly expressed apolipoprotein in the brain afterApoE (DeMattos et al, 2001)
It is important to highlight that a major route of amy loid-β (Aβ) transport at the cerebral vascular endothelium and choroid plexus epithelium involves the cellular uptake of clusterin-Aβ complexes by gp330/megalin, known as low density lipoprotein-related protein 2 (LRP-2) receptor (Zlokovic et al, 1996) with more recent in vitro studies demonstrating enhanced Aβ40 trafficking through endothelial cell monolayers when the peptide is previously complexed to clusterin (Merino-Zamorano et al, 2016)
The anti-clusterin antibody strongly labeled blood vessels as well as paren chymal amyloid plaques and diffuse preamyloid deposits in familial British dementia (FBD) tissue, exhibiting a pattern closely overlapping that of the previously described for ABri deposition (Holton et al, 2001)

Summary

Introduction

Known as apolipoprotein J (ApoJ), is a ubiquitous protein present in most body fluids (Calero et al, 2005; Calero et al, 2000) and the most highly expressed apolipoprotein in the brain afterApoE (DeMattos et al, 2001). The presence of clusterin-Aβ complexes in plasma and CSF supports the role of the apolipoprotein as a major Aβ-transport molecule (Ghiso et al, 1993). In this context, it is important to highlight that a major route of Aβ transport at the cerebral vascular endothelium and choroid plexus epithelium involves the cellular uptake of clusterin-Aβ complexes by gp330/megalin, known as LRP-2 receptor (Zlokovic et al, 1996) with more recent in vitro studies demonstrating enhanced Aβ40 trafficking through endothelial cell monolayers when the peptide is previously complexed to clusterin (Merino-Zamorano et al, 2016)

Methods

Results

Conclusion