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Acta Neuropathologica Communications May 2024In Parkinson's disease and other synucleinopathies, fibrillar forms of α-synuclein (aSyn) are hypothesized to structurally convert and pathologize endogenous aSyn,...
Effects of local reduction of endogenous α-synuclein using antisense oligonucleotides on the fibril-induced propagation of pathology through the neural network in wild-type mice.
In Parkinson's disease and other synucleinopathies, fibrillar forms of α-synuclein (aSyn) are hypothesized to structurally convert and pathologize endogenous aSyn, which then propagates through the neural connections, forming Lewy pathologies and ultimately causing neurodegeneration. Inoculation of mouse-derived aSyn preformed fibrils (PFFs) into the unilateral striatum of wild-type mice causes widespread aSyn pathologies in the brain through the neural network. Here, we used the local injection of antisense oligonucleotides (ASOs) against Snca mRNA to confine the area of endogenous aSyn protein reduction and not to affect the PFFs properties in this model. We then varied the timing and location of ASOs injection to examine their impact on the initiation and propagation of aSyn pathologies in the whole brain and the therapeutic effect using abnormally-phosphorylated aSyn (pSyn) as an indicator. By injecting ASOs before or 0-14 days after the PFFs were inoculated into the same site in the left striatum, the reduction in endogenous aSyn in the striatum leads to the prevention and inhibition of the regional spread of pSyn pathologies to the whole brain including the contralateral right hemisphere. ASO post-injection inhibited extension from neuritic pathologies to somatic ones. Moreover, injection of ASOs into the right striatum prevented the remote regional spread of pSyn pathologies from the left striatum where PFFs were inoculated and no ASO treatment was conducted. This indicated that the reduction in endogenous aSyn protein levels at the propagation destination site can attenuate pSyn pathologies, even if those at the propagation initiation site are not inhibited, which is consistent with the original concept of prion-like propagation that endogenous aSyn is indispensable for this regional spread. Our results demonstrate the importance of recruiting endogenous aSyn in this neural network propagation model and indicate a possible potential for ASO treatment in synucleinopathies.
Topics: Animals; alpha-Synuclein; Oligonucleotides, Antisense; Mice, Inbred C57BL; Mice; Nerve Net; Male; Corpus Striatum; Disease Models, Animal; Brain; RNA, Messenger
PubMed: 38745295
DOI: 10.1186/s40478-024-01766-3 -
ACS Chemical Neuroscience Jun 2024Prion diseases are invariably fatal neurodegenerative diseases of humans and other animals for which there are no effective treatment options. Previous work from our...
Prion diseases are invariably fatal neurodegenerative diseases of humans and other animals for which there are no effective treatment options. Previous work from our laboratory identified phenethylpiperidines as a novel class of anti-prion compounds. While working to identify the molecular target(s) of these molecules, we unexpectedly discovered ten novel antiprion compounds based on their known ability to bind to the sigma receptors, σR and σR, which are currently being tested as therapeutic or diagnostic targets for cancer and neuropsychiatric disorders. Surprisingly, however, knockout of the respective genes encoding σR and σR ( and ) in prion-infected N2a cells did not alter the antiprion activity of these compounds, demonstrating that these receptors are not the direct targets responsible for the antiprion effects of their ligands. Further investigation of the most potent molecules established that they are efficacious against multiple prion strains and protect against downstream prion-mediated synaptotoxicity. While the precise details of the mechanism of action of these molecules remain to be determined, the present work forms the basis for further investigation of these compounds in preclinical studies. Given the therapeutic utility of several of the tested compounds, including rimcazole and haloperidol for neuropsychiatric conditions, (+)-pentazocine for neuropathic pain, and the ongoing clinical trials of SA 4503 and ANAVEX2-73 for ischemic stroke and Alzheimer's disease, respectively, this work has immediate implications for the treatment of human prion disease.
Topics: Receptors, sigma; Animals; Ligands; Prion Diseases; Mice; Humans; Prions; Sigma-1 Receptor; Cell Line, Tumor
PubMed: 38743607
DOI: 10.1021/acschemneuro.4c00095 -
Molecular Neurobiology May 2024PRNP Q160X is one of the five dominantly inheritable nonsense mutations causing familial prion diseases. Till now, it remains unclear how this type of nonsense mutations...
PRNP Q160X is one of the five dominantly inheritable nonsense mutations causing familial prion diseases. Till now, it remains unclear how this type of nonsense mutations causes familial prion diseases with unique clinical and pathological characteristics. Human prion protein (PrP) Q160X mutation is equivalent to Q159X in mouse PrP, which produces the mutant fragment PrP1-158. Through intracerebroventricular injection of recombinant adeno-associated virus in newborn mice, we successfully overexpressed mouse PrP1-158-FLAG in the central nervous system. Interestingly, high level PrP1-158-FLAG expression in the brain caused death in these mice with an average survival time of 60 ± 9.1 days. Toxicity correlated with levels of PrP1-158-FLAG but was independent of endogenous PrP. Histopathological analyses showed microgliosis and astrogliosis in mouse brains expressing PrP1-158-FLAG and most of PrP1-158-FLAG staining appeared intracellular. Biochemical characterization revealed that the majority of PrP1-158-FLAG were insoluble and a significant part of PrP1-158-FLAG appeared to contain an un-cleaved signal peptide that may contribute to its cytoplasmic localization. Importantly, an ~10-kDa proteinase K-resistant PrP fragment was detected, which was the same as those observed in patients suffering from this type of prion diseases. To our knowledge, this is the first animal study of familial prion disease caused by Q159X that recapitulates key features of human disease. It will be a valuable tool for investigating the pathogenic mechanisms underlying familial prion diseases caused by nonsense mutations.
PubMed: 38743210
DOI: 10.1007/s12035-024-04224-2 -
Nature Cancer May 2024Cancer immunotherapy with chimeric antigen receptor (CAR) T cells can cause immune effector cell-associated neurotoxicity syndrome (ICANS). However, the molecular...
Cancer immunotherapy with chimeric antigen receptor (CAR) T cells can cause immune effector cell-associated neurotoxicity syndrome (ICANS). However, the molecular mechanisms leading to ICANS are not well understood. Here we examined the role of microglia using mouse models and cohorts of individuals with ICANS. CD19-directed CAR (CAR19) T cell transfer in B cell lymphoma-bearing mice caused microglia activation and neurocognitive deficits. The TGFβ-activated kinase-1 (TAK1)-NF-κB-p38 MAPK pathway was activated in microglia after CAR19 T cell transfer. Pharmacological TAK1 inhibition or genetic Tak1 deletion in microglia using Cx3cr1:Tak1 mice resulted in reduced microglia activation and improved neurocognitive activity. TAK1 inhibition allowed for potent CAR19-induced antilymphoma effects. Individuals with ICANS exhibited microglia activation in vivo when studied by translocator protein positron emission tomography, and imaging mass cytometry revealed a shift from resting to activated microglia. In summary, we prove a role for microglia in ICANS pathophysiology, identify the TAK1-NF-κB-p38 MAPK axis as a pathogenic signaling pathway and provide a rationale to test TAK1 inhibition in a clinical trial for ICANS prevention after CAR19 T cell-based cancer immunotherapy.
PubMed: 38741011
DOI: 10.1038/s43018-024-00764-7 -
Prion Dec 2024Although the development of aggregation assays has noticeably improved the accuracy of the clinical diagnosis of prion diseases, research on biomarkers remains vital.... (Review)
Review
Although the development of aggregation assays has noticeably improved the accuracy of the clinical diagnosis of prion diseases, research on biomarkers remains vital. The major challenges to overcome are non-invasive sampling and the exploration of new biomarkers that may predict the onset or reflect disease progression. This will become extremely important in the near future, when new therapeutics are clinically evaluated and eventually become available for treatment. This article aims to provide an overview of the achievements of biomarker research in human prion diseases, addresses unmet needs in the field, and points out future perspectives.
Topics: Humans; Biomarkers; Prion Diseases; Animals
PubMed: 38734978
DOI: 10.1080/19336896.2024.2349017 -
International Journal of Molecular... May 2024Tau protein misfolding and aggregation are pathological hallmarks of Alzheimer's disease and over twenty neurodegenerative disorders. However, the molecular mechanisms... (Review)
Review
Tau protein misfolding and aggregation are pathological hallmarks of Alzheimer's disease and over twenty neurodegenerative disorders. However, the molecular mechanisms of tau aggregation in vivo remain incompletely understood. There are two types of tau aggregates in the brain: soluble aggregates (oligomers and protofibrils) and insoluble filaments (fibrils). Compared to filamentous aggregates, soluble aggregates are more toxic and exhibit prion-like transmission, providing seeds for templated misfolding. Curiously, in its native state, tau is a highly soluble, heat-stable protein that does not form fibrils by itself, not even when hyperphosphorylated. In vitro studies have found that negatively charged molecules such as heparin, RNA, or arachidonic acid are generally required to induce tau aggregation. Two recent breakthroughs have provided new insights into tau aggregation mechanisms. First, as an intrinsically disordered protein, tau is found to undergo liquid-liquid phase separation (LLPS) both in vitro and inside cells. Second, cryo-electron microscopy has revealed diverse fibrillar tau conformations associated with different neurodegenerative disorders. Nonetheless, only the fibrillar core is structurally resolved, and the remainder of the protein appears as a "fuzzy coat". From this review, it appears that further studies are required (1) to clarify the role of LLPS in tau aggregation; (2) to unveil the structural features of soluble tau aggregates; (3) to understand the involvement of fuzzy coat regions in oligomer and fibril formation.
Topics: tau Proteins; Humans; Protein Aggregation, Pathological; Animals; Alzheimer Disease; Protein Aggregates
PubMed: 38732197
DOI: 10.3390/ijms25094969 -
PrP is cleaved from the surface of mast cells by ADAM10 and proteases released during degranulation.Journal of Leukocyte Biology May 2024While several functions of the endogenous prion protein (PrP) have been studied, the homeostatic function of PrP is still debated. Notably, PrP is highly expressed on...
While several functions of the endogenous prion protein (PrP) have been studied, the homeostatic function of PrP is still debated. Notably, PrP is highly expressed on mast cells, granular immune cells that regulate inflammation. When activated, mast cells shed PrP though the mechanism and consequences of this are not yet understood. First, we tested several mast cell lines and found that, while PrP was almost always present, the total amount differed greatly. Activation of mast cells induced a cleavage of the N-terminal region of PrP, and this was reduced by protease inhibitors. Exogenous mast cell proteases caused a similar loss of the PrP N-terminus. Additionally, mast cells shed PrP in an ADAM10-dependent fashion even in the absence of activation. Our results suggest that PrP is cleaved from resting mast cells by ADAM10 and from activated mast cells by mast cell proteases. PrP also appears to affect mast cell function, as Prnp-/- BMMC showed lower levels of degranulation and cytokine release, as well as lower levels of both FcεRI and CD117. Finally, we sought to provide clinical relevance by measuring the levels of PrP in bodily fluids of asthmatic patients, a disease that involves the activation of mast cells. We found an N-terminal fragment of PrP could be detected in human sputum and serum and the amount of this PrP fragment was decreased in the serum of patients with asthma.
PubMed: 38725289
DOI: 10.1093/jleuko/qiae099 -
Neurochemistry International Jul 2024Neurodegenerative diseases such as Parkinson's disease (PD) are characterized by the death of neurons in specific areas of the brain. One of the proteins that is... (Review)
Review
Neurodegenerative diseases such as Parkinson's disease (PD) are characterized by the death of neurons in specific areas of the brain. One of the proteins that is involved in the pathogenesis of PD is α-synuclein (α-syn). α-Syn is a normal protein that is found in all neurons, but in PD, it misfolds and aggregates into toxic fibrils. These fibrils can then coalesce into pathological inclusions, such as Lewy bodies and Lewy neurites. The pathogenic pathway of PD is thought to involve a number of steps, including misfolding and aggregation of α-syn, mitochondrial dysfunction, protein clearance impairment, neuroinflammation and oxidative stress. A deeper insight into the structure of α-syn and its fibrils could aid in understanding the disease's etiology. The prion-like nature of α-syn is also an important area of research. Prions are misfolded proteins that can spread from cell to cell, causing other proteins to misfold as well. It is possible that α-syn may behave in a similar way, spreading from cell to cell and causing a cascade of misfolding and aggregation. Various post-translational alterations have also been observed to play a role in the pathogenesis of PD. These alterations can involve a variety of nuclear and extranuclear activities, and they can lead to the misfolding and aggregation of α-syn. A better understanding of the pathogenic pathway of PD could lead to the development of new therapies for the treatment of this disease.
Topics: alpha-Synuclein; Humans; Parkinson Disease; Protein Folding; Animals; Lewy Bodies
PubMed: 38723900
DOI: 10.1016/j.neuint.2024.105760 -
Prion Dec 2024Authors are commenting on the evolving geographical incidence trends observed with the genetic form of Creutzfeldt-Jakob disease and discussing the diverse array of...
Authors are commenting on the evolving geographical incidence trends observed with the genetic form of Creutzfeldt-Jakob disease and discussing the diverse array of factors contributing to the heightened incidence rates observed in specific geographical regions.
Topics: Creutzfeldt-Jakob Syndrome; Humans; Incidence; Slovakia
PubMed: 38722257
DOI: 10.1080/19336896.2024.2349011 -
The Journal of Biological Chemistry Jun 2024Lethal neurodegenerative prion diseases result from the continuous accumulation of infectious and variably protease-resistant prion protein aggregates (PrP) which are...
Lethal neurodegenerative prion diseases result from the continuous accumulation of infectious and variably protease-resistant prion protein aggregates (PrP) which are misfolded forms of the normally detergent soluble and protease-sensitive cellular prion protein. Molecular chaperones like Grp78 have been found to reduce the accumulation of PrP, but how different cellular environments and other chaperones influence the ability of Grp78 to modify PrP is poorly understood. In this work, we investigated how pH and protease-mediated structural changes in PrP from two mouse-adapted scrapie prion strains, 22L and 87V, influenced processing by Grp78 in the presence or absence of chaperones Hsp90, DnaJC1, and Stip1. We developed a cell-free in vitro system to monitor chaperone-mediated structural changes to, and disaggregation of, PrP. For both strains, Grp78 was most effective at structurally altering PrP at low pH, especially when additional chaperones were present. While Grp78, DnaJC1, Stip1, and Hsp90 were unable to disaggregate the majority of PrP from either strain, pretreatment of PrP with proteases increased disaggregation of 22L PrP compared to 87V, indicating strain-specific differences in aggregate structure were impacting chaperone activity. Hsp90 also induced structural changes in 87V PrP as indicated by an increase in the susceptibility of its n-terminus to proteases. Our data suggest that, while chaperones like Grp78, DnaJC1, Stip1, and Hsp90 disaggregate only a small fraction of PrP, they may still facilitate its clearance by altering aggregate structure and sensitizing PrP to proteases in a strain and pH-dependent manner.
Topics: Endoplasmic Reticulum Chaperone BiP; Animals; Hydrogen-Ion Concentration; Heat-Shock Proteins; Mice; Molecular Chaperones; HSP40 Heat-Shock Proteins; HSP90 Heat-Shock Proteins; Protein Aggregates
PubMed: 38718859
DOI: 10.1016/j.jbc.2024.107346