Biology subjects

Herzog, L.

Publications and source records attributed to Herzog, L..

6 recordsLinked to original sources

bioRxiv2024

Human PrP E219K as a new and promising substrate for RT-QuIC amplification of human prion strains: a first step towards strain discrimination

Prion diseases are fatal neurodegenerative diseases that affect mammals through the transconformation of a host protein, the prion protein (PrP), into a toxic and pathogenic conformer termed PrPSc. Until now, the diagnosis is only confirmed with a post-mortem histology study of the central nervous system. Among the methods to detect the etiological agent, in vitro amplification techniques have emerged as very sensitive, highly specific and rapid tools, even though some prion strains remain refractory or difficult to amplify. Here we report the use of a new recombinant substrate for Real-Time Quaking Induced Conversion (RT-QuIC), a natural polymorphism of human prion protein with a lysine at position 219 instead of a glutamic acid, PrP E219K. This substrate amplifies the six sporadic human strains responsible for Creutzfeldt-Jakob Disease (CJD) and the strain responsible for its variant form in a few hours and over a large dilution range of the seeds. Moreover, based on the lag time of the amplification reactions, the PrP E219K substrate allows to discriminate between sporadic and variant CJD strains, a first step towards an ante-mortem typing of the prion strain affecting a patient.

pathology↗

bioRxiv2023

Chemogenetic inhibition of IST1-CHMP1B interaction impairs endosomal recycling and promotes unconventional LC3 lipidation at stalled endosomes

The Endosomal Sorting Complex Required for Transport (ESCRT) machinery constitutes a multisubunit protein complex that plays an essential role in membrane remodeling and trafficking. ESCRTs regulate a wide array of cellular processes, encompassing cytokinetic abscission, cargo sorting into multivesicular bodies (MVBs), membrane repair and autophagy. Given the versatile functionality of ESCRTs and the intricate organizational structure of the ESCRT complex, the targeted modulation of distinct ESCRT-mediated membrane deformations for functional dissection poses a considerable challenge. This study presents a pseudo-natural product targeting IST1-CHMP1B within the ESCRT-III complex. This compound specifically disrupts the interaction between IST1 and CHMP1B, thereby inhibiting the formation of IST1-CHMP1B copolymers essential for normal-topology membrane scission events. While the compound has no impact on cytokinesis, MVB sorting and exosome biogenesis, it rapidly hinders transferrin receptor (TfR) recycling in cells, resulting in the accumulation of transferrin in perinuclear endosomal recycling tubules. Stalled recycling endosomes acquire unconventional LC3 lipidation, establishing a link between non-canonical LC3 lipidation and endosomal recycling.

cell biology↗

bioRxiv2023

The smallest infectious substructure encoding the prion strain structural determinant revealed by spontaneous dissociation of misfolded prion protein assemblies

It is commonly accepted that the prion replicative propensity and strain structural determinant (SSD) are encoded in the fold of PrPSc amyloid fibril assemblies. By exploring the quaternary structure dynamicity of several prion strains, we revealed that all mammalian prion assemblies exhibit the generic property of spontaneously generating two sets of discreet infectious tetrameric and dimeric species differing significantly by their specific infectivity. By using perturbation approaches such as dilution and ionic strength variation, we demonstrated that these two oligomeric species were highly dynamic and evolved differently in the presence of chaotropic agents. In general, our observations of seven different prion strains from three distinct species highlight the high dynamicity of PrPSc assemblies as a common and intrinsic property of mammalian prions. The existence of such small infectious PrPSc species harboring the SSD indicates that the prion infectivity and the SSD are not restricted only to the amyloid fold but can also be encoded in other alternative quaternary structures. Such diversity in the quaternary structure of prion assemblies tends to indicate that the structure of PrPSc can be divided into two independent folding domains: a domain encoding the strain structural determinant and a second domain whose fold determines the type of quaternary structure that could adopt PrPSc assemblies. HighlightsO_LIMammalian prion assemblies are highly dynamic C_LIO_LIPrion assemblies spontaneously disassemble into two infectious oligomers C_LIO_LIPrion infectivity is not exclusively encoded in the amyloid fibrils structure C_LIO_LITwo independent folding domains could structure Prion assemblies C_LI

biochemistry↗

bioRxiv2023

Pathogenicity, strain properties and interspecies transmission capacity of pure recombinant prion protein assemblies

The pathogenicity of fibrillar assemblies derived from bacterially expressed recombinant prion protein (rPrP) has been key to the demonstration that prions are infectious proteins responsible for human and animal transmissible spongiform encephalopathies. Yet, their use in identifying which structural PrP features are important for prion biology, including strain properties and capacity to transmit between species, has been hampered by their limited transmissibility de novo. We report the generation of prions with distinct biological characteristics from rPrP assemblies differing only in their primary structure (hamster, mouse and human amino acid sequence). These rPrP assemblies were transmissible to transgenic mice expressing hamster PrP, causing a clinical disease at full attack rate, brain deposition of pathological prion protein PrPSc and spongiform degeneration. Their adaptation process on serial sub-passaging seemed to depend, as for genuine prions, on the presence of a species/transmission barrier, due notably to PrP sequence mismatch. Remarkably, one of the strains obtained is an unprecedented shortened prion, lacking the 90-140 amino-acid region which is believed to be key to infectivity and structural stability of disease-associated PrP assemblies. Finally, we provide evidence that rPrP prionogenicity lies in the structural organization and/or heterogeneity of the rPrP assemblies. These preparations of rPrP offer unprecedented opportunities for meaningful studies correlating the dynamicity and structures of PrPSc assemblies to prion pathobiology. Author summaryPrions are infectious proteins, causing rapidly progressive neurodegenerative diseases in animals and humans. They are formed from the assisted-refolding and aggregation of the host-encoded prion protein (PrP). During the propagation of the disease, pathological PrP forces normal PrP to adopt its own conformation by a self-templating process. In infected host, different pathological structures of PrP or strains are found, causing diseases with specific biological phenotypes. Prions can also transmit between species. This capacity is limited by a species barrier, which critically depends on the infecting strain and PrP primary structure. How strain biological information is encoded in PrP structural fold remains unknown. We describe here the generation of different bona fide prion strains with markedly distinct adaptation capacities by transmission of refolded assemblies derived from bacterially-derived recombinant PrP (rPrP) of different species. We provide evidence that pathogenicity lies in the structural organization and/or heterogeneity of rPrP assemblies. Pathological PrP from one of the generated strains exhibited unique molecular features, including absence of domains that are thought to be key to prion infectivity, according to most recent ultrastructural studies. Our findings provide new insights for generating prion infectious material and resolving mechanisms of infectivity acquisition during PrP conversion process.

microbiology↗

bioRxiv2019

Complementation between pathological prion protein subassemblies to cross existing species barriers

Backgroundprion replication results from the autocatalytic templated assisted conversion of the host-encoded prion protein PrPC into misfolded, polydisperse PrPSc conformers. Structurally distinct PrPSc conformers can give rise to multiple prion strains. Within and between prion strains, the biological activity (replicative efficacy and specific infectivity) of PrPSc assemblies is size-dependent and thus reflects an intrinsic structural heterogeneity. The contribution of such PrPSc heterogeneity across species prion adaptation, - which is believed to be based on fit-adjustment between PrPSc template(s) and host PrPC -, has not been explored. Methodsto define the structural-to-fitness PrPSc landscape, we measured the relative capacity of size-fractionated PrPSc assemblies from different prion strains to cross mounting species barriers in transgenic mice expressing foreign PrPc. Resultsin the absence of a transmission barrier, the relative efficacy of the isolated PrPSc assemblies to induce the disease is superimposable to the efficacy observed in the homotypic context. However, in the presence of a transmission barrier, size fractionation overtly delays and even abrogates prion pathogenesis in both neural and extraneural, prion-permissive tissues, for reason independent of the infectivity load of the isolated assemblies. This suggests that a synergy between structurally distinct PrPSc assemblies in the inoculum is requested for crossing the species barrier. We further strengthen this hypothesis by showing that altering, by serial dilution, PrPSc assemblies content of unfractionated inocula reduce their specific infectivity in an aberrant manner, solely in the presence of a transmission barrier. Conclusionsour data support a mechanism whereby overcoming prion species barrier requires complementation between structurally distinct PrPSc assemblies. This work provides key insight into the "quasi-species" concept applied to prions, which would not necessarily rely on prion sub-strains as constituent but on structural PrPSc heterogeneity within prion population.

neuroscience↗

bioRxiv2019

Quaternary structural convergence and structural diversification of prion assemblies at the early replication stage

Aggregation of misfolded forms from host-encoded proteins is key to the pathogenesis of a number of neurodegenerative disorders, including prion diseases, Alzheimers disease and Parkinsons disease. In prion diseases, the cellular prion protein PrPC can misfold into PrPSc and auto-organize into conformationally distinct assemblies or strains. A plethora of observations reports the existence of PrPSc structural heterogeneity within prion strains, suggesting the emergence and coevolution of structurally distinct PrPSc assemblies during prion replication in controlled environment. Such PrPSc diversification processes remain poorly understood. Although central to prion host-adaptation, structural diversification of PrPSc assemblies is also a key issue for the formation of PrP conformers involved in neuronal injury. Here, we characterized the evolution of the PrPSc quaternary structure during prion replication in vivo and in bona fide cell-free amplification assays. Regardless of the strain studied, the early replication stage conduced to the preferential formation of small PrPSc oligomers, thus highlighting a quaternary structural convergence phenomenon. Their evolutionary kinetics revealed the existence of a PrPC-dependent secondary templating pathway in concert with a structural rearrangement. This secondary templating pathway provides, for the first time, a mechanistic explanation for prion structural diversification during replication, a key determinant for prion adaptation on further transmission, including to other host species. The uncovered processes are also key for a better understanding of the accumulation mechanisms of other misfolded assemblies believed to propagate by a prion-like process.

biochemistry↗