Biology subjects

Nuvolone, M.

Publications and source records attributed to Nuvolone, M..

13 recordsLinked to original sources

bioRxiv2025

Exploring light chain cardiotoxicity in AL amyloidosis: Impact on hiPSC-derived Cardiomyocyte Activity

AimsImmunoglobulin light chain (AL) amyloidosis is a protein misfolding disease characterized by the systemic deposition of amyloid fibrils derived from monoclonal light chains (LCs). Cardiac involvement is the major determinant of prognosis and mortality, and beyond fibril accumulation, soluble cardiotoxic LCs play a critical role in disease progression. While current in vivo models like C. elegans and murine systems have demonstrated LC toxicity, they lack human relevance or fail to capture soluble LC-induced cardiotoxicity. This study aimed to characterize the electrophysiological effects of cardiotoxic LCs on a human-relevant model using human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Methods and ResultsTwo amyloidogenic cardiotoxic LCs (H3 and H6) from AL patients and one non-cardiotoxic LC (M10) from a multiple myeloma patient were biophysically characterized and tested in hiPSC-CMs at clinically relevant concentrations. Electrophysiological recordings revealed that H3 and H6 significantly reduced spontaneous action potential (AP) firing frequency and maximal upstroke velocity (dV/dt) in hiPSC-CMs, indicating impaired excitability. H6 also shortened AP duration. H3 exposure led to a [~]40% reduction in peak sodium current density and altered inactivation kinetics of the L-type calcium current, without affecting major pacemaker or repolarizing potassium (IKr or IKs) currents. In contrast, M10 had no effect on any measured parameter, validating the models ability to discriminate toxic from non-toxic LCs. ConclusionThis study demonstrates that hiPSC-CMs provide a clinically relevant human model to investigate LC-induced cardiotoxicity. Cardiotoxic LCs exert distinct but converging electrophysiological impairments, including disruption of sodium and L-type calcium currents, contributing to reduced excitability and altered AP morphology. These findings provide mechanistic insights into AL amyloidosis-related cardiac dysfunction and establish a foundation for future therapeutic screening targeting soluble LC toxicity in a human context.

pathology↗

bioRxiv2024

A conformational fingerprint for amyloidogenic light chains.

Immunoglobulin light chain amyloidosis (AL) and multiple myeloma (MM) both share the overproduction of a clonal light chain (LC). However, while LCs in MM remain soluble in circulation, AL LCs misfold into toxic soluble species and amyloid fibrils that accumulate in organs, leading to distinct clinical manifestations. The significant sequence variability of LCs has hindered understanding of the mechanisms driving LC aggregation. Nevertheless, emerging biochemical properties, including dimer stability, conformational dynamics, and proteolysis susceptibility, distinguish AL LCs from those in MM under native conditions. This study aimed to identify a conformational fingerprint distinguishing AL from MM LCs. Using small-angle X-ray scattering (SAXS) under native conditions, we analyzed four AL and two MM LCs. We observed that AL LCs exhibited a slightly larger radius of gyration and greater deviations from X-ray crystallography-determined or predicted structures, reflecting enhanced conformational dynamics. SAXS data, integrated with molecular dynamics (MD) simulations, revealed a conformational ensemble where LCs adopt multiple states, with variable and constant domains either bent or straight. AL LCs displayed a distinct, low-populated, straight conformation (termed H state), which maximized solvent accessibility at the interface between constant and variable domains. Hydrogen-deuterium exchange mass spectrometry (HDX-MS) experimentally validated this H state. These findings reconcile diverse experimental observations and provide a precise structural target for future drug design efforts.

biophysics↗

bioRxiv2024

Modeling Immunoglobulin light chain amyloidosis in Caenorhabditis elegans

Cardiomyopathy determines the prognosis of patients with immunoglobulin light chain (AL) amyloidosis, a rare systemic disease caused by the misfolding and deposition of monoclonal light chains (LCs). The reasons underlining their cardiac tropism remain unknown, and an animal model recapitulating the main pathological features of AL amyloidosis is instrumental. Taking advantage of the similarities between the vertebrate heart and C. elegans pharynx, we developed a new transgenic nematode expressing a human amyloidogenic {lambda} LC whose sequence was deduced from a patient suffering from AL amyloidosis with cardiac involvement (MNH). Strains expressing a non-amyloidogenic LC (MNM) or the empty vector only (MNV) were generated as controls. At variance with controls, LCs expressed in the body-wall muscle of MNH worms formed native soluble dimeric assemblies, which were secreted and reached different organs, including the pharynx. Noteworthy, MNH worms exerted a pharyngeal impairment resembling cardiac functional impairment occurring in patients with AL, accompanied by increased radical oxygen species production and tissue ultrastructural damage. This new animal model can allow the elucidation of the mechanisms underlying the cardiac-specific tropism occurring in AL amyloidosis, providing innovative insights into the pathophysiology.

pathology↗

bioRxiv2024

Involvement of the cellular prion protein in seeding and spreading of sarkosyl-derived fractions of Alzheimer's disease in Prnp mutant mice and in the P301S transgenic tauopathy mice model

The natural cellular prion protein is known to play several roles during development and adult brain. Far from its pathological roles in prionopathies, the non-pathogenic cellular prion protein has been described as a receptor for several amyloid in oligomeric and prefibrillar forms. For some amyloids, specific domains of the protein play a crucial role in modulating amyloids cellular uptake and seeding properties. In most studies, the functions and the role of putative amyloid receptors have been analyzed by using brain extracts derived from human neurodegenerative patients. Another strategy has been to modify the genetic dosage of the natural prion protein in genetic models of different diseases. In this study, we take advantage of both approaches to examine whether this protein plays a role in the seeding and spreading of pathogenic tau. Our results point to a role of the natural prion protein in the emergence of pathogenic tau in a mouse model overexpressing the mutation P301S of the human tau gene. In contrast, its role is minor when sarkosyl-derived brain samples of Alzheimers disease are used. In fact, our results indicate that the use of this type of sample is not adequate to determine the role of a putative receptor in tau seeding and spreading.

neuroscience↗

bioRxiv2023

Skeletal-Muscle Glutamine Synthase is Upregulated in Preclinical Prion Diseases

In prion diseases, aggregates of misfolded prion protein (PrPSc) accumulate not only in the brain but also in extraneural organs. This raises the question whether prion-specific pathologies arise also extraneurally. Here we sequenced mRNA transcripts in skeletal muscle, spleen and blood of prion-inoculated mice at eight timepoints during disease progression. We detected gene-expression changes in all three organs, with skeletal muscle showing the most consistent alterations. The glutamate-ammonia ligase (GLUL) gene exhibited uniform upregulation in skeletal muscles of mice infected with three distinct scrapie prion strains (RML, ME7, and 22L) and in victims of human sporadic Creutzfeldt-Jakob disease. GLUL dysregulation was accompanied by changes in glutamate/glutamine metabolism, leading to reduced glutamate levels in skeletal muscle. None of these changes were observed in skeletal muscle of humans with amyotrophic lateral sclerosis, Alzheimers disease, or dementia with Lewy bodies, suggesting that they are specific to prion diseases. These findings reveal an unexpected metabolic dimension of prion infections and point to a potential role for GLUL dysregulation in the glutamate/glutamine metabolism in prion-affected skeletal muscle.

neuroscience↗

bioRxiv2023

Nanobodies counteract the toxicity of an amyloidogenic light chain by stabilizing a partially open dimeric conformation

Light chain amyloidosis (AL) is a systemic disease where fibrillar deposition of misfolded immunoglobulin light chains (LCs) severely affects organ function and results in poor prognosis for patients, especially when heart involvement is severe. Particularly relevant in this context is the cardiotoxicity exerted by still uncharacterized soluble LC species. Here, with the final goal of identifying alternative therapeutic strategies to tackle AL amyloidosis, we produced five llama-derived nanobodies (Nbs) specific against H3, a well-characterized amyloidogenic and cardiotoxic LC from an AL patient with severe cardiac involvement. We found that Nbs are specific and potent agents capable of abolishing H3 soluble toxicity in C. elegans in vivo model. Structural characterization of H3-Nb complexes revealed that the protective effect of Nbs is related to their ability to bind to the H3 VL domain and stabilise an unexpected partially open LC dimer in which the two VL domains no longer interact with each other. Thus, while identifying potent inhibitors of LC soluble toxicity, we also describe the first non-native structure of an amyloidogenic LC that may represent a crucial step in toxicity and aggregation mechanisms.

biophysics↗

bioRxiv2022

Cryo-EM structure of ex vivo fibrils associated with extreme AA amyloidosis prevalence in a cat shelter

AA amyloidosis is a systemic disease characterized by deposition of misfolded serum amyloid A protein (SAA) into cross-{beta} amyloid in multiple organs in humans and animals. AA amyloidosis occurs at high SAA serum levels during chronic inflammation. The disease can be transmitted horizontally, likely facilitated by prion-like mechanism, in captive animals leading to extreme disease prevalence, e.g. 70% in captive cheetah and 57-73% in domestic short hair (DSH) cats kept in shelters. Herein, we present the 3.3 [A] cryo-EM structure of an AA amyloid extracted post-mortem from the kidney of a DSH cat with renal failure. The structure reveals a cross-{beta} architecture assembled from two 76-residue long proto-filaments. Despite >70% sequence homology to mouse and human SAA, the cat SAA variant adopts a distinct amyloid fold. Based on shared disease profiles and almost identical protein sequences, we propose a similar amyloid fold of deposits identified previously in captive cheetah.

biophysics↗

bioRxiv2022

Brain aging is faithfully modelled in organotypic brain slices and accelerated by prions

Mammalian models are essential for brain aging research. However, the long lifespan and limited amenability to genetic and pharmacological perturbations have hindered the use of mammals for dissecting aging-regulatory molecular networks and discovering new anti-aging interventions. To circumvent these limitations, we developed an ex vivo model system that faithfully mimics the aging process of the mammalian brain using cultured mouse brain slices. Genome-wide gene expression analyses showed that brain slices spontaneously upregulated senescence-associated genes over time and reproduced many of the transcriptional characteristics of aged brains. Treatment with rapamycin, a classical anti-aging compound, largely abolished the time-dependent transcriptional changes in brain slices. Using this model system, we discovered that prions drastically accelerated the development of age-related molecular signatures and the pace of brain aging. We confirmed this finding in mouse models and human victims of Creutzfeldt-Jakob disease. These data establish a novel, eminently tractable mammalian model of brain aging, and uncover a surprising acceleration of brain aging in prion diseases.

neuroscience↗

bioRxiv2021

The ASC Protein Controls the Severity of Systemic AA Amyloidosis in Mice

ASC-containing inflammasomes form specks, extracellular aggregates which enhance the aggregation of A{beta} amyloid in Alzheimers disease. This raises the question whether ASC participates to additional aggregation proteinopathies. Here we show that ASC controls the extent of inflammation-associated AA amyloidosis, a systemic disease caused by the aggregation of the acute-phase reactant serum amyloid A (SAA). Using superresolution microscopy, we found that ASC colocalized tightly with SAA in human AA amyloidosis. Purified recombinant ASC specks accelerated SAA fibril formation in vitro. Mass spectrometry after limited proteolysis showed that ASC interacts with SAA via its pyrin domain. In a murine model of inflammation-associated AA amyloidosis, splenic AA amyloid load was conspicuously decreased in Pycardtm1Vmd/tm1Vmd mice which lack ASC. This reduction was not a consequence of enhanced amyloid phagocytosis, as SAA stimulation increased phagocytic activity in Pycard+/+, but not in Pycard-/- macrophages. Treatment with anti-ASC antibodies decreased the amyloid loads in wild-type mice suffering from AA amyloidosis. The prevalence of natural anti-ASC IgG (-logEC50 [≥] 2) in 19,334 hospital patients was <0.01%, suggesting that anti-ASC antibody treatment modalities would not be confounded by natural autoimmunity. Higher anti-ASC titers did not correlate with any specific disease, suggesting that anti-ASC immunotherapy may be well-tolerated. These findings expand the role played by ASC to extraneural proteinopathies of humans and experimental animals and suggest that anti-ASC immunotherapy may contribute to resolving such diseases.

molecular biology↗

bioRxiv2021

Behavioral deficits, learning impairment, and enhanced hippocampal excitability in co-isogenic PrnpZH3/ZH3 mice

BackgroundThe cellular prion protein (PrPC) has been associated with numerous cellular processes, such as cell differentiation and neurotransmission. Moreover, it was recently demonstrated that some functions were misattributed to PrPC since results were obtained from mouse models with genetic artifacts. Here we elucidate the role of PrPC in the hippocampal circuitry and its related functions, like learning and memory, using the new strictly co-isogenic Prnp0/0 mouse (PrnpZH3/ZH3). Behavioral and operant conditioning tests were performed to evaluate memory and learning capabilities. In vivo electrophysiological recordings were carried out at CA3-CA1 synapses in living behaving mice, and spontaneous neuronal firing and network formation were monitored in primary neuronal cultures of PrnpZH3/ZH3 vs. wild-type mice. ResultsResults showed decreased motility, impaired operant conditioning learning, and anxiety-related behavior in PrnpZH3/ZH3 animals. PrPC absence enhanced susceptibility to high-intensity stimulations and kainate-induced seizures. However, long-term potentiation (LTP) was not enhanced in the PrnpZH3/ZH3 hippocampus. In addition, we observed a delay in neuronal maturation and network formation in PrnpZH3/ZH3 cultures. ConclusionIn conclusion, PrPC mediates synaptic function and protects the synapse from excitotoxic insults. Its deletion might evoke a susceptible epileptogenic brain that would fail to perform highly cognitive-demanding tasks such as associative learning and anxiety-like behaviors.

neuroscience↗

bioRxiv2021

Glial activation in prion diseases is strictly nonautonomous and requires neuronal PrPSc

Although prion infections cause cognitive impairment and neuronal death, transcriptional and translational profiling shows progressive derangement within glia but surprisingly little changes within neurons. Here we expressed PrPC selectively in neurons, astrocytes or oligodendrocytes of mice. After prion infection, both astrocyte and neuron-restricted PrPC expression led to copious brain accumulation of PrPSc. As expected, neuron-restricted expression was associated with typical prion disease. However, mice with astrocyte-restricted PrPC expression experienced a normal life span, did not develop clinical disease, and did not show astro- or microgliosis. Besides confirming that PrPSc is innocuous to PrPC-deficient neurons, these results show that astrocyte-born PrPSc does not activate the extreme neuroinflammation that accompanies the onset of prion disease and precedes any molecular changes of neurons. This points to a nonautonomous mechanism by which prion-infected neurons instruct astrocytes and microglia to acquire a specific cellular state that, in turn, drives neural dysfunction.

neuroscience↗

bioRxiv2020

Genome-wide transcriptomics identifies an early preclinical signature of prion infection

The clinical course of prion diseases is accurately predictable despite long latency periods, suggesting that prion pathogenesis is driven by precisely timed molecular events. We constructed a searchable genome-wide atlas of mRNA abundance, splicing and editing alterations during the course of disease in prion-inoculated mice. Prion infection induced transient changes in mRNA abundance and processing already at eight weeks post inoculation, well ahead of any neuropathological and clinical signs. In contrast, microglia-enriched genes displayed an increase simultaneous with the appearance of clinical symptoms, whereas neuronal-enriched transcripts remained unchanged until the very terminal stage of disease. This suggests that glial pathophysiology, rather than neuronal demise, represents the final driver of disease. The administration of young plasma attenuated the occurrence of early mRNA abundance alterations and delayed symptoms in the terminal phase of the disease. The early onset of prion-induced molecular changes might thus point to novel biomarkers and potential interventional targets.

neuroscience↗

bioRxiv2018

Lymphocyte activation gene 3 (Lag3) is upregulated by prions but does not contribute to disease

Prion diseases, Alzheimers disease and Parkinsons disease (PD) are fatal degenerative disorders that share common neuropathological and biochemical features, including the aggregation of pathological protein conformers. Lymphocyte activation gene 3 (Lag3, also known as CD223) is a member of the immunoglobulin superfamily of receptors expressed on peripheral immune cells, microglia and neurons, which serves as a receptor for -synuclein aggregates in PD. Here we examined the possible role of Lag3 in the pathogenesis of prion diseases. Through quantitative real-time PCR and RNA-sequencing, we found that the expression levels of Lag3 were relatively low in the adult mouse brains, yet its expression was increased after prion infection. However, we failed finding significant differences regarding the incubation time, PrPSc load, neurodegeneration, astrocyte and microglia reactions and inflammatory gene expression between the Lag3 knockout mice and wild-type littermate controls after prion infection. We conclude that loss of Lag3 has no significant influence on prion disease pathogenesis. Considering that Lag3 is an immune checkpoint receptor, our results suggest that immune checkpoint inhibition (an increasingly prevalent therapeutic modality against many types of cancer) might not exert positive or negative effects on the progression of prion diseases.

neuroscience↗