Biology subjects

Kluve-Beckerman, B.

Publications and source records attributed to Kluve-Beckerman, B..

6 recordsLinked to original sources

bioRxiv2025

A Shared Amyloid Architecture in Cardiac Fibrils from Three Neuropathy-Associated ATTR Variants

ATTR amyloidosis results from the systemic accumulation of wild-type (ATTRwt) or mutant (ATTRv) transthyretin amyloids, leading to multi-organ dysfunction and death. The disease exhibits variable pathology and penetrance, and its relationship with the amyloid structure remains unclear. Patients carrying the neuropathy-associated variants ATTRvI84S and ATTRv-V122{Delta} present polymorphic ATTR fibrils, in contrast to the consistent morphology reported for most ATTR fibrils to date. Here, we aim to elucidate a potential link between neuropathic symptomatology, distinct mutations, and amyloid structural diversity, using cryo-EM. We determined the ex-vivo fibril structures from the variants ATTRv-P24S, ATTRv-A25S, and ATTRv-D38A, whose patients presented variable clinical manifestations, including neuropathy. Our findings revealed that, despite differences in mutations and diverse clinical phenotypes, these variants share a common amyloid core previously identified in ATTRwt and several other cardiac ATTRv. This structural consistency is significant for the development of structure-guided diagnostic tools capable of addressing the diverse spectrum of ATTR amyloidosis. HighlightsO_LIDetermines transthyretin amyloid structures of three human ATTRv by cryo-EM C_LIO_LIDetermines the structure of three ex-vivo ATTRv fibrils linked to polyneuropathy. C_LIO_LIReveals structural similarities of ATTRv amyloid cores. C_LIO_LIReveals a common fold despite the different mutations and symptomatology. C_LIO_LIContributes to the understanding of transthyretin aggregation in patients with diverse phenotypes C_LI

biophysics↗

bioRxiv2025

Structural polymorphism of ex-vivo ALECT2 amyloid fibrils revealed by cryo-EM

ALECT2 amyloidosis is a rare systemic disease characterized by the pathological deposition of leukocyte cell-derived chemotaxin-2 (LECT2) as amyloid fibrils, primarily affecting the kidneys and liver. The molecular mechanisms underlying LECT2 aggregation remain poorly defined, hindering diagnostic and therapeutic development. Here, we present cryo-electron microscopy structures of ex-vivo ALECT2 fibrils extracted from a patients kidney. We identified three fibril polymorphs: a predominant single-protofilament morphology and two minor double-protofilament morphologies. The dominant single-protofilament morphology comprises the full-length 133-residue LECT2 protein and retains all three native disulfide bonds. Low-resolution reconstructions of double-protofilament morphologies suggest they adopt a similar fold to the single protofilament morphology, but form paired assemblies with different inter-filament interfaces. Mass spectrometry also reveals acetylation within the fibrils. These findings offer critical insights into the structural basis of ALECT2 amyloid formation and identify molecular features that could inform future diagnostic and therapeutic approaches.

biophysics↗

bioRxiv2025

Structural variability of apolipoprotein A-I amyloid fibrils across organs, mutations, and clinical presentations, revealed by cryo-EM

Hereditary apolipoprotein A-I (AapoA-I) amyloidosis is a rare systemic disease caused by the deposition of amyloid fibrils formed by apolipoprotein A-I in multiple organs, leading to severe clinical outcomes. With no available therapies or diagnostic tools, defining the structure of AApoA-I fibrils is crucial to understanding disease mechanisms and guiding intervention. Using cryo-electron microscopy, we analyzed AApoA-I fibrils from the heart, kidney, liver, and spleen of patients carrying G26R, L90P, and R173P mutations. G26R fibrils, regardless of organ, exhibited untwisted morphologies and could not be resolved structurally. Conversely, L90P and R173P fibrils displayed a compact diabolo-shaped conformation in all organs analyzed. Their high-resolution maps enabled visualization of cis-Proline 66, which may represent a potential conformational switch during fibril formation. Our findings suggest that mutation-driven polymorphism may influence organ tropism and clinical presentation. This work advances our understanding of AapoA-I fibril assembly and provides insights toward developing targeted clinical tools.

biophysics↗

bioRxiv2024

ATTRv-V30M Type A amyloid fibrils from the heart and nerves exhibit structural homogeneity.

ATTR amyloidosis is a systemic disease characterized by the deposition of amyloid fibrils made of transthyretin, a protein integral to transporting retinol and thyroid hormones. Transthyretin is primarily produced by the liver and circulates in blood as a tetramer. The retinal epithelium also secretes transthyretin, which is secreted to the vitreous humor of the eye. Because of mutations or aging, transthyretin can dissociate into amyloidogenic monomers triggering amyloid fibril formation. The deposition of transthyretin amyloid fibrils in the myocardium and peripheral nerves causes cardiomyopathies and neuropathies, respectively. Using cryo-electron microscopy, here we determined the structures of amyloid fibrils extracted from cardiac and nerve tissues of an ATTRv-V30M patient. We found that fibrils from both tissues share a consistent structural conformation, similar to the previously described structure of cardiac fibrils from an individual with the same genotype, but different from the fibril structure obtained from the vitreous humor. Our study hints to a uniform fibrillar architecture across different tissues within the same individual, only when the source of transthyretin is the liver. Moreover, this study provides the first description of ATTR fibrils from the nerves of a patient and enhances our understanding of the role of deposition site and protein production site in shaping the fibril structure in ATTRv-V30M amyloidosis.

biophysics↗

bioRxiv2024

Amyloid fibril polymorphism in the heart of an ATTR amyloidosis patient with polyneuropathy attributed to the V122Δ variant

ATTR amyloidosis is a phenotypically heterogeneous disease characterized by the pathological deposition of transthyretin in the form of amyloid fibrils into various organs. ATTR amyloidosis may result from mutations in variant (ATTRv) amyloidosis, or aging in wild-type (ATTRwt) amyloidosis. ATTRwt generally manifests as cardiomyopathy, whereas ATTRv may present as polyneuropathy, cardiomyopathy, or mixed, in combination with many other symptoms deriving from multisystem organ involvement. Over 220 different mutational variants of transthyretin have been identified, many of them being linked to specific disease symptoms. Yet, the role of these mutations in explaining differential disease manifestations remains unclear. Using cryo-electron microscopy, here we structurally characterized fibrils from the heart and the liver of an ATTRv patient carrying the V122{Delta} mutation, which is predominantly associated with polyneuropathy. Our results show that these fibrils are polymorphic, presenting as both single and double filaments. Our study alludes to a structural connection contributing to phenotypic variation in ATTR amyloidosis, as polymorphism in ATTR fibrils may manifest in patients with predominantly polyneuropathic phenotypes. SignificanceATTR amyloidosis is a systemic, clinically diverse disease that results in organ failure due to the accumulation of transthyretin amyloid fibrils. ATTR patients present with varied symptoms, yet the root of this phenotypic heterogeneity remains unclear. Previous studies suggest an association between phenotype and fibril structure polymorphism. Here we describe the cryo-electron microscopy structure of variant transthyretin amyloid fibrils associated with a predominantly polyneuropathy phenotype. We have found polymorphism within these fibrils, a phenomenon we have thus far only observed in polyneuropathic associated transthyretin mutations. Our results signify an association between fibril structure and phenotype in ATTR amyloidosis.

molecular biology↗

bioRxiv2024

Cryo-EM confirms a common fibril fold in the heart of four patients with ATTRwt amyloidosis

ATTR amyloidosis results from the conversion of transthyretin into amyloid fibrils that deposit in tissues causing organ failure and death. This conversion is facilitated by mutations in ATTRv amyloidosis, or aging in ATTRwt amyloidosis. ATTRv amyloidosis exhibits extreme phenotypic variability, whereas ATTRwt amyloidosis presentation is consistent and predictable. Previously, we found an unprecedented structural variability in cardiac amyloid fibrils from polyneuropathic ATTRv-I84S patients. In contrast, cardiac fibrils from five genotypically-different patients with cardiomyopathy or mixed phenotypes are structurally homogeneous. To understand fibril structures impact on phenotype, it is necessary to study the fibrils from multiple patients sharing genotype and phenotype. Here we show the cryo-electron microscopy structures of fibrils extracted from four cardiomyopathic ATTRwt amyloidosis patients. Our study confirms that they share identical conformations with minimal structural variability, consistent with their homogenous clinical presentation. Our study contributes to the understanding of ATTR amyloidosis biopathology and calls for further studies. One-Sentence Summary: Wild-type cardiac ATTR fibrils are structurally homogeneous.

biophysics↗