Project description:Immunoglobulin light chain (LC) amyloidosis (AL) is one of the most common types of systemic amyloidosis. The lack of reliable in vivo models hinders the study of the disease in its physiological context. We developped a transgenic mouse model producing high amounts of a human AL free light chain (LC). While mice exceptionnaly develop spontaneous AL amyloidosis and do not exhibit organ toxicity due to the circulating amyloidogenic LC, a single injection of amyloid fibrils, made up of the variable domain (VL) of the human LC, or soluble VL led to amyloid deposits, mainly in heart. The biochemical composition and the fragmentation pattern of the LC in the fibrils are highly similar to that of human AL fibrils, arguing for a conserved mechanism of amyloid fibrils formation. Amyloidosis positive mice also develop an early cardiac dysfunction, with increased NT-proBNP, diastolic dysfunction and remodeling of the extracellular matrix. Overall, this transgenic mice closely reproduces human cardiac AL amyloidosis and shows that a partial degradation of the LC initiate amyloid fibril formations in vivo. Accumulation of AL amyloid fibrils, rather than the soluble LC, drive the initial cardiac dysfunction. This model fills an important gap for research on AL amyloidosis and preclinical evaluation of new therapies.
Project description:we investigated the N-glycosylation of the amyloid fibrils extracted from the heart of a patient affected by AL amyloidosis, using a proteomic approach to evaluate indirectly the presence of glycans in immunoglobulin light chains.
Project description:We investigated the N- and C-terminome of the LCs proteoforms in fibrils extracted from the hearts of a patient affected by AL amyloidosis, using a proteomic approach based on N- and C-terminal residues derivatization, followed by mapping of fragmentation sites on the structures of fibrillar LCs
Project description:Mimivirus 1.2Mb genome is organized into a 30 nm nucleocapsid-like structure made of two closely related GMC-oxidoreductases, also composing the fibrils decorating its virions. In this work, we used MS-proteomics to characterize the protein content of virions and fibrils from different members of the Mimiviridae family (clade A: Mimivirus reunion -Mr- and Mimivirus M4 -M4, clade B: Moumouvirus australiensis -Ma- and Moumouvirus maliensis -Mm, clade C: Megavirus chilensis -Mc- and Megavirus vitis -Mv). Furthermore, we analyzed fractions purified from Mr mutants devoid of one of the two GMC-oxidoreductases (Mr_KOqu_143 and Mr_KOqu_946), or of both GMC-oxidoreductases (Mr_2KO) with or without expression of the GFP fused to the N-terminus of one GMC-oxidoreductase (Mr_2KO-GFP). Our results show the versatility of the protein content of the fibrils, with fibrils composed of different proteins inter- and even intra-clade, clades B and C viruses presenting fibrils with a protein composition closer to each other than that of clade A viruses.
Project description:Isolated atrial amyloidosis (IAA) is a localized cardiac disorder characterized by atrial natriuretic peptide (ANP) amyloids deposition in the atria, linked to aging and atrial fibrillation (AF). While monomeric ANP regulates blood pressure, its dimeric form is associated with cardiovascular conditions, including AF. The mechanistic link between ANP aggregation, IAA, and AF remains unclear. Here, we present the first high-resolution structural characterization of ANP fibrils extracted from AF patients, revealing two distinct fibril polymorphs. Both present covalent ANP dimers as building blocks but diverge in their structural architecture: one features antiparallel dimers stabilized by a single disulfide bond, while the other consists of parallel dimers bridged by two interchain disulfide bonds. These fibril morphologies were conserved across patients, suggesting a common aggregation mechanism in IAA. Overall, our findings ascribe to dimeric ANP a critical role in amyloid formation, offering promising directions for earlier detection and treatment of IAA.
Project description:Immunoglobulin light chain (AL) amyloidosis is characterized by deposition of abnormal amyloid fibrils in multiple organs impairing their function. CD138-purified plasma cells producing these fibrils are investigated regarding chromosomal alterations by interphase fluorescence in situ hybridization (iFISH) using a multiple myeloma specific probe set for the IgH translocations as well as recurrent numerical aberrations. Aberrations genuine to AL amyloidosis cannot be detected due to the inherent limitation of this probe panel to known loci. We analyzed 118 AL amyloidosis patients by high-density copy number array to quantitatively detect genome-wide chromosomal imbalances. Most prevalent gains affected chromosomes 1q (37%), 9 (24%), 11q (24%), and 19 (16%). The most frequent deletion was monosomy 13 (28%) followed by partial deletions on 14q (21%), 16q (14%), and 13q (12%). The results were analyzed with respect to cytogenetic subgroups. In 88% of patients with translocation t(11;14) and concomitant gain of 11q22.3/11q23 detected by iFISH, the latter aberration was not due to trisomy of chromosome 11 but part of the unbalanced translocation der(14)t(11;14)(q13;q32) with breakpoint in the CCND1/MYEOV gene region. Partial loss of chromosomes 14q and 16q were significantly associated to patients with gain 1q. Our iFISH probe set is highly concordant with copy number results as it detects the most common cytogenetic aberrations present in AL amyloidosis. Beyond that, the probe panel is also the method of choice to detect translocations involving the IgH locus. In contrast to the results of our iFISH panel the frequency of hyperdiploidy detected by copy number array analysis is higher.
Project description:Light chain amyloidosis (AL) is a life-threatening plasma cell dyscrasia manifested by irreversible damage of multiple organs caused by monoclonal immunoglobulin light chain, production of pathogenic bone marrow plasma cells (BMPCs). Although AL is featured by both misfolding of monoclonal protein and plasma cell proliferation, the functional subclones and molecular mechanism of BMPCs in AL remain elusive. Also, inter-individual heterogeneities of AL determine the chemotherapy response and organ tropism of light chains, which require well-defined molecular subtypes. To address these, we conducted single-cell RNA sequencing (scRNA-seq) of BMPCs donated by patients with AL, patients with monoclonal gammopathy of undetermined significance (MGUS), and healthy controls. Single-cell transcriptome revealed a continuity of bone marrow plasma cell (BMPC) functional subclones, delineating DNA repair, cell proliferation, immunoglobulin production, etc., with the gradient of signaling entropy and immunoglobulin production. The amyloidosis-associated genes, such as the amyloid-beta binding Apolipoprotein E (APOE), Cystatin 3 (CST3), and Complement C1q A Chain (C1QA), were up-regulated in a subclone enriched in AL. The speculated light chain-producing subclones in AL up-regulated neutrophil degranulation pathways, transport to and modifications in Golgi apparatus, and asparagine N-linked protein glycosylation. Cyclin D1 (CCND1)hi AL, consisted of larger main subclones which highly expressed Bcl-2 complex and B-cell differentiation genes, was sensitive to venetoclax that targets Bcl-2. A major subset of CCND1low AL harbored larger carbohydrate-synthesizing subclone and up-regulated CCND2 and the amyloidosis-associated genes. Collectively, our results provided frontier insights into the functional subclones and molecular mechanism of BMPCs in AL, associated with amyloidosis, light chain production and venetoclax sensitivity, as knowledge for the future research on AL pathogenesis, AL subtypes and AL-specific therapies.
Project description:Transthyretin-derived amyloidosis (ATTR) is a degenerative, systemic disease characterized by transthyretin fibril deposition in organs like the heart, kidneys, liver, and skin. We report the first cryo-EM structure of transthyretin fibrils isolated from skin tissue of a living patient with a rare genetic mutation (ATTRv F64S). The structure adopts a highly conserved fold previously observed in other ATTR fibrils from different tissues or genetic variants. Mass spectrometry was used to identify common post-translational modifications. The structural consistency between ATTR filaments validates non-invasive skin biopsy as a diagnostic tool.