scholarly journals Peripherally expressed misfolded proteins remotely disrupt brain function and aggravate stroke-induced brain injury

2019 ◽  
Author(s):  
Yanying Liu ◽  
Kalpana Subedi ◽  
Aravind Baride ◽  
Svetlana Romanova ◽  
Christa C. Huber ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Brain Function ◽  
Small Heat Shock Protein ◽  
Brain Dysfunction ◽  
Misfolded Proteins ◽  
Wild Type ◽  
Mouse Blood ◽  
Αb Crystallin ◽  
The Impact ◽  
The Brain

AbstractImpaired proteostasis has been linked to various diseases, whereas little is known about the impact of peripherally misfolded proteins on the brain. We here studied the brain of mice with cardiomyocyte-restricted overexpression of a missense (R120G) mutant small heat shock protein, αB-crystallin (CryABR120G). At baseline, the CryABR120G mice showed impaired cognitive and motor functions, aberrant protein aggregates, neuroinflammation, impaired blood-brain barrier, and reduced proteasome activity in the brain compared with their non-transgenic (Ntg) littermates. Ischemic stroke dramatically exacerbated these pathological alterations and caused more severe brain dysfunction in CryABR120G mice than in the Ntg mice. Intravenously injecting the exosomes isolated from CryABR120G mouse blood into wild-type mice caused the similar phenotypes seen from CryABR120G mice. Importantly, the CryABR120G protein showed the prion-like properties. These results suggest that peripherally misfolded proteins in the heart remotely disrupt brain function through prion-like neuropathology, which may represent an underappreciated mechanism underlying heart-brain crosstalk.

scholarly journals Peripherally misfolded proteins exacerbate ischemic stroke-induced neuroinflammation and brain injury

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Yanying Liu ◽  
Kalpana Subedi ◽  
Aravind Baride ◽  
Svetlana Romanova ◽  
Eduardo Callegari ◽  
...  
Keyword(s):  
Ischemic Stroke ◽  
Brain Injury ◽  
Cell Cultures ◽  
Functional Recovery ◽  
Protein Aggregates ◽  
Mass Spectrometric ◽  
Misfolded Proteins ◽  
Spectrometric Analysis ◽  
Mouse Blood ◽  
The Brain

Abstract Background Protein aggregates can be found in peripheral organs, such as the heart, kidney, and pancreas, but little is known about the impact of peripherally misfolded proteins on neuroinflammation and brain functional recovery following ischemic stroke. Methods Here, we studied the ischemia/reperfusion (I/R) induced brain injury in mice with cardiomyocyte-restricted overexpression of a missense (R120G) mutant small heat shock protein, αB-crystallin (CryABR120G), by examining neuroinflammation and brain functional recovery following I/R in comparison to their non-transgenic (Ntg) littermates. To understand how peripherally misfolded proteins influence brain functionality, exosomes were isolated from CryABR120G and Ntg mouse blood and were used to treat wild-type (WT) mice and primary cortical neuron-glia mix cultures. Additionally, isolated protein aggregates from the brain following I/R were isolated and subjected to mass-spectrometric analysis to assess whether the aggregates contained the mutant protein, CryABR120G. To determine whether the CryABR120G misfolding can self-propagate, a misfolded protein seeding assay was performed in cell cultures. Results Our results showed that CryABR120G mice exhibited dramatically increased infarct volume, delayed brain functional recovery, and enhanced neuroinflammation and protein aggregation in the brain following I/R when compared to the Ntg mice. Intriguingly, mass-spectrometric analysis of the protein aggregates isolated from CryABR120G mouse brains confirmed presence of the mutant CryABR120G protein in the brain. Importantly, intravenous administration of WT mice with the exosomes isolated from CryABR120G mouse blood exacerbated I/R-induced cerebral injury in WT mice. Moreover, incubation of the CryABR120G mouse exosomes with primary neuronal cultures induced pronounced protein aggregation. Transduction of CryABR120G aggregate seeds into cell cultures caused normal CryAB proteins to undergo dramatic aggregation and form large aggregates, suggesting self-propagation of CryABR120G misfolding in cells. Conclusions These results suggest that peripherally misfolded proteins in the heart remotely enhance neuroinflammation and exacerbate brain injury following I/R likely through exosomes, which may represent an underappreciated mechanism underlying heart-brain crosstalk.

scholarly journals Imaging Sterols and Oxysterols in Mouse Brain Reveals Distinct Spatial Cholesterol Metabolism

2018 ◽  
Author(s):  
Eylan Yutuc ◽  
Roberto Angelini ◽  
Mark Baumert ◽  
Natalia Mast ◽  
Irina Pikuleva ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Mouse Brain ◽  
Brain Function ◽  
Mass Spectrometry Imaging ◽  
Cholesterol Metabolism ◽  
Biologically Active ◽  
Wild Type ◽  
Tissue Slices ◽  
The Brain

AbstractDysregulated cholesterol metabolism is implicated in a number of neurological disorders. Many sterols, including cholesterol and its precursors and metabolites, are biologically active and important for proper brain function. However, spatial cholesterol metabolism in brain and the resulting sterol distributions are poorly defined. To better understand cholesterol metabolism in situ across the complex functional regions of brain, we have developed on-tissue enzyme-assisted derivatisation in combination with micro-liquid-extraction for surface analysis and liquid chromatography - mass spectrometry to image sterols in tissue slices (10 µm) of mouse brain. The method provides sterolomic analysis at 400 µm spot diameter with a limit of quantification of 0.01 ng/mm2. It overcomes the limitations of previous mass spectrometry imaging techniques in analysis of low abundance and difficult to ionise sterol molecules, allowing isomer differentiation and structure identification. Here we demonstrate the spatial distribution and quantification of multiple sterols involved in cholesterol metabolic pathways in wild type and cholesterol 24S-hydroxylase knock-out mouse brain. The technology described provides a powerful tool for future studies of spatial cholesterol metabolism in healthy and diseased tissues.SignificanceThe brain is a remarkably complex organ and cholesterol homeostasis underpins brain function. It is known that cholesterol is not evenly distributed across different brain regions, however, the precise map of cholesterol metabolism in the brain remains unclear. If cholesterol metabolism is to be correlated with brain function it is essential to generate such a map. Here we describe an advanced mass spectrometry imaging platform to reveal spatial cholesterol metabolism in situ at 400 µm resolution on 10 µm tissue slices from mouse brain. We mapped, not only cholesterol, but also other biologically active sterols arising from cholesterol turnover in both wild type and mice lacking cholesterol 24-hydroxylase (Cyp46a1), the major cholesterol metabolising enzyme.

scholarly journals Single-molecule fluorescence-based approach reveals novel mechanistic insights into human small heat shock protein chaperone function

2020 ◽  
pp. jbc.RA120.015419
Author(s):  
Caitlin L Johnston ◽  
Nicholas R Marzano ◽  
Bishnu P Paudel ◽  
George Wright ◽  
Justin L.P. Benesch ◽  
...  
Keyword(s):  
Heat Shock ◽  
Single Molecule ◽  
Small Heat Shock Protein ◽  
Vital Role ◽  
Misfolded Proteins ◽  
Single Molecule Fluorescence ◽  
Chaperone Function ◽  
Αb Crystallin ◽  
Client Proteins ◽  
Shock Proteins

Small heat shock proteins (sHsps) are a family of ubiquitous intracellular molecular chaperones that are up-regulated under stress conditions and play a vital role in protein homeostasis (proteostasis). It is commonly accepted that these chaperones work by trapping misfolded proteins to prevent their aggregation; however, fundamental questions regarding the molecular mechanism by which sHsps interact with misfolded proteins remain unanswered. The dynamic and polydisperse nature of sHsp oligomers has made studying them challenging using traditional biochemical approaches. Therefore, we have utilized a single-molecule fluorescence-based approach to observe the chaperone action of human αB-crystallin (αBc, HSPB5). Using this approach we have, for the first time, determined the stoichiometries of complexes formed between αBc and a model client protein, chloride intracellular channel 1 (CLIC1). By examining the dispersity and stoichiometries of these complexes over time, and in response to different concentrations of αBc, we have uncovered unique and important insights into a two-step mechanism by which αBc interacts with misfolded client proteins to prevent their aggregation.

scholarly journals Disturbance of Intracerebral Fluid Clearance and Blood–Brain Barrier in Vascular Cognitive Impairment

2019 ◽  
Vol 20 (10) ◽  
pp. 2600 ◽  
Author(s):  
Masaki Ueno ◽  
Yoichi Chiba ◽  
Ryuta Murakami ◽  
Koichi Matsumoto ◽  
Ryuji Fujihara ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Blood Brain Barrier ◽  
Brain Function ◽  
Vascular Cognitive Impairment ◽  
Brain Dysfunction ◽  
Brain Parenchyma ◽  
The Other ◽  
Brain Barrier ◽  
Blood Brain ◽  
The Brain

The entry of blood-borne macromolecular substances into the brain parenchyma from cerebral vessels is blocked by the blood–brain barrier (BBB) function. Accordingly, increased permeability of the vessels induced by insult noted in patients suffering from vascular dementia likely contributes to the cognitive impairment. On the other hand, blood-borne substances can enter extracellular spaces of the brain via endothelial cells at specific sites without the BBB, and can move to brain parenchyma, such as the hippocampus and periventricular areas, adjacent to specific sites, indicating the contribution of increased permeability of vessels in the specific sites to brain function. It is necessary to consider influx and efflux of interstitial fluid (ISF) and cerebrospinal fluid (CSF) in considering effects of brain transfer of intravascular substances on brain function. Two pathways of ISF and CSF are recently being established. One is the intramural peri-arterial drainage (IPAD) pathway of ISF. The other is the glymphatic system of CSF. Dysfunction of the two pathways could also contribute to brain dysfunction. We review the effects of several kinds of insult on vascular permeability and the failure of fluid clearance on the brain function.

scholarly journals MALT1 Controls Attenuated Rabies Virus by Inducing Early Inflammation and T Cell Activation in the Brain

2018 ◽  
Vol 92 (8) ◽  
Author(s):  
E. Kip ◽  
J. Staal ◽  
L. Verstrepen ◽  
H. G. Tima ◽  
S. Terryn ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Virus Infection ◽  
Rabies Virus ◽  
T Cell Activation ◽  
Therapeutic Target ◽  
Cell Activation ◽  
Wild Type ◽  
The Impact ◽  
The Brain

ABSTRACTMALT1 is involved in the activation of immune responses, as well as in the proliferation and survival of certain cancer cells. MALT1 acts as a scaffold protein for NF-κB signaling and a cysteine protease that cleaves substrates, further promoting the expression of immunoregulatory genes. Deregulated MALT1 activity has been associated with autoimmunity and cancer, implicating MALT1 as a new therapeutic target. Although MALT1 deficiency has been shown to protect against experimental autoimmune encephalomyelitis, nothing is known about the impact of MALT1 on virus infection in the central nervous system. Here, we studied infection with an attenuated rabies virus, Evelyn-Rotnycki-Abelseth (ERA) virus, and observed increased susceptibility with ERA virus in MALT1−/−mice. Indeed, after intranasal infection with ERA virus, wild-type mice developed mild transient clinical signs with recovery at 35 days postinoculation (dpi). Interestingly, MALT1−/−mice developed severe disease requiring euthanasia at around 17 dpi. A decreased induction of inflammatory gene expression and cell infiltration and activation was observed in MALT1−/−mice at 10 dpi compared to MALT1+/+infected mice. At 17 dpi, however, the level of inflammatory cell activation was comparable to that observed in MALT1+/+mice. Moreover, MALT1−/−mice failed to produce virus-neutralizing antibodies. Similar results were obtained with specific inactivation of MALT1 in T cells. Finally, treatment of wild-type mice with mepazine, a MALT1 protease inhibitor, also led to mortality upon ERA virus infection. These data emphasize the importance of early inflammation and activation of T cells through MALT1 for controlling the virulence of an attenuated rabies virus in the brain.IMPORTANCERabies virus is a neurotropic virus which can infect any mammal. Annually, 59,000 people die from rabies. Effective therapy is lacking and hampered by gaps in the understanding of virus pathogenicity. MALT1 is an intracellular protein involved in innate and adaptive immunity and is an interesting therapeutic target because MALT1-deregulated activity has been associated with autoimmunity and cancers. The role of MALT1 in viral infection is, however, largely unknown. Here, we study the impact of MALT1 on virus infection in the brain, using the attenuated ERA rabies virus in different models of MALT1-deficient mice. We reveal the importance of MALT1-mediated inflammation and T cell activation to control ERA virus, providing new insights in the biology of MALT1 and rabies virus infection.

scholarly journals Nucleosomal association and altered interactome underlie the mechanism of cataract caused by the R54C mutation of αA-crystallin

2020 ◽  
Author(s):  
Saad M. Ahsan ◽  
Bakthisaran Raman ◽  
Tangirala Ramakrishna ◽  
Ch. Mohan Rao
Keyword(s):  
Molecular Basis ◽  
Quaternary Structure ◽  
Nuclear Translocation ◽  
Intracellular Localization ◽  
Small Heat Shock Protein ◽  
Chaperone Activity ◽  
Wild Type ◽  
Terminal Domain ◽  
Αb Crystallin ◽  
Arginine Residues

AbstractThe small heat shock protein (sHSP), αA-crystallin, plays an important role in eye lens development. It has three distinct domains viz. the N-terminal domain, α-crystallin domain and the C-terminal extension. While the α-crystallin domain is conserved across the sHSP family, the N-terminal domain and the C-terminal extension are comparatively less conserved. Nevertheless, certain arginine residues in the N-terminal region of αA-crystallin are conserved across the sHSP family. Interestingly, most of the cataractcausing mutations in αA-crystallin occur in the conserved arginine residues. In order to understand the molecular basis of cataract caused by the R54C mutation in human αA-crystallin, we have compared the structure, chaperone activity, intracellular localization, effect on cell viability and “interactome” of wild-type and mutant αA-crystallin. Although R54CαA-crystallin exhibited slight changes in quaternary structure, its chaperone activity was comparable to that of the wild-type. When expressed in lens epithelial cells, R54CαA-crystallin triggered a stress-like response, resulting in nuclear translocation of αB-crystallin, disassembly of cytoskeletal elements and activation of Caspase 3, leading to apoptosis. Comparison of the “interactome” of the wild-type and mutant proteins revealed a striking increase in the interaction of the mutant protein with nucleosomal histones (H2A, H2B, H3 and H4). Using purified chromatin fractions, we show an increased association of R54CαA-crystallin with these nucleosomal histones, suggesting the potential role of the mutant in transcriptional modulation. Thus, the present study shows that alteration of “interactome” and its nucleosomal association, rather than loss of chaperone activity, is the molecular basis of cataract caused by the R54C mutation in αA-crystallin.

scholarly journals Current Paradigms to Explore the Gut Microbiota Linkage to Neurological Disorders

EMJ Neurology ◽  
2020 ◽  
pp. 68-79
Author(s):  
Varruchi Sharma ◽  
Atul Sankhyan ◽  
Anshika Varshney ◽  
Renuka Choudhary ◽  
Anil K. Sharma
Keyword(s):  
Gut Microbiota ◽  
Neurological Disorders ◽  
Brain Function ◽  
Intervention Strategy ◽  
Neurological Complications ◽  
Communication Link ◽  
Brain Functions ◽  
Current Review ◽  
The Impact ◽  
The Brain

It has been suggested that an intricate communication link exists between the gut microbiota and the brain and its ability to modulate behaviour of an individual governing homeostasis. Metabolic activity of the microbiota is considered to be relatively constant in healthy individuals, despite differences in the composition of microbiota. The metabolites produced by gut microbiota and their homeostatic balance is often perturbed as a result of neurological complications. Therefore, it is of paramount importance to explore the link between gut microbiota and brain function and behaviour through neural, endocrine, and immune pathways. This current review focusses on the impact of altered gut microbiota on brain functions and how microbiome modulation by use of probiotics, prebiotics, and synbiotics might prove beneficial in the prevention and/or treatment of neurological disorders. It is important to carefully understand the complex mechanisms underlying the gut–brain axis so as to use the gut microbiota as a therapeutic intervention strategy for neurological disorders.

scholarly journals CCR2 deficiency in monocytes impairs angiogenesis and functional recovery after ischemic stroke in mice

2020 ◽  
Vol 40 (1_suppl) ◽  
pp. S98-S116 ◽  
Author(s):  
Jordi Pedragosa ◽  
Francesc Miró-Mur ◽  
Amaia Otxoa-de-Amezaga ◽  
Carles Justicia ◽  
Francisca Ruíz-Jaén ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Ischemic Stroke ◽  
Functional Recovery ◽  
Behavioral Performance ◽  
Wild Type ◽  
Ischemic Brain ◽  
Arginase 1 ◽  
Angiogenic Genes ◽  
The Brain

Inflammatory Ly6ChiCCR2+ monocytes infiltrate the brain after stroke but their functions are not entirely clear. We report that CCR2+ monocytes and CCR2+ lymphocytes infiltrate the brain after permanent ischemia. To underscore the role of CCR2+ monocytes, we generated mice with selective CCR2 deletion in monocytes. One day post-ischemia, these mice showed less infiltrating monocytes and reduced expression of pro-inflammatory cytokines, markers of alternatively macrophage activation, and angiogenesis. Accordingly, Ly6Chi monocytes sorted from the brain of wild type mice 24 h post-ischemia expressed pro-inflammatory genes, M2 genes, and pro-angiogenic genes. Flow cytometry showed heterogeneous phenotypes within the infiltrating Ly6ChiCCR2+ monocytes, including a subgroup of Arginase-1+ cells. Mice with CCR2-deficient monocytes displayed a delayed inflammatory rebound 15 days post-ischemia that was not found in wild type mice. Furthermore, they showed reduced angiogenesis and worse behavioral performance. Administration of CCR2+/+ bone-marrow monocytes to mice with CCR2-deficient monocytes did not improve the behavioral performance suggesting that immature bone-marrow monocytes lack pro-reparative functions. The results show that CCR2+ monocytes contribute to acute post-ischemic inflammation and participate in functional recovery. The study unravels heterogeneity in the population of CCR2+ monocytes infiltrating the ischemic brain and suggests that pro-reparative monocyte subsets promote functional recovery after ischemic stroke.

scholarly journals The impact of diet-based glycaemic response and glucose regulation on cognition: evidence across the lifespan

2017 ◽  
Vol 76 (4) ◽  
pp. 466-477 ◽  
Author(s):  
Sandra I. Sünram-Lea ◽  
Lauren Owen
Keyword(s):  
Blood Glucose ◽  
Cognitive Function ◽  
Brain Function ◽  
Healthy Lifestyle ◽  
Glucose Deprivation ◽  
Glucose Regulation ◽  
Glycaemic Response ◽  
Glucose Levels ◽  
The Impact ◽  
The Brain

The brain has a high metabolic rate and its metabolism is almost entirely restricted to oxidative utilisation of glucose. These factors emphasise the extreme dependence of neural tissue on a stable and adequate supply of glucose. Whereas initially it was thought that only glucose deprivation (i.e. under hypoglycaemic conditions) can affect brain function, it has become apparent that low-level fluctuations in central availability can affect neural and consequently, cognitive performance. In the present paper the impact of diet-based glycaemic response and glucose regulation on cognitive processes across the lifespan will be reviewed. The data suggest that although an acute rise in blood glucose levels has some short-term improvements of cognitive function, a more stable blood glucose profile, which avoids greater peaks and troughs in circulating glucose is associated with better cognitive function and a lower risk of cognitive impairments in the longer term. Therefore, a habitual diet that secures optimal glucose delivery to the brain in the fed and fasting states should be most advantageous for the maintenance of cognitive function. Although the evidence to date is promising, it is insufficient to allow firm and evidence-based nutritional recommendations. The rise in obesity, diabetes and metabolic syndrome in recent years highlights the need for targeted dietary and lifestyle strategies to promote healthy lifestyle and brain function across the lifespan and for future generations. Consequently, there is an urgent need for hypothesis-driven, randomised controlled trials that evaluate the role of different glycaemic manipulations on cognition.

scholarly journals αB-crystallin regulation of angiogenesis by modulation of VEGF

Blood ◽  
2010 ◽  
Vol 115 (16) ◽  
pp. 3398-3406 ◽  
Author(s):  
Satoru Kase ◽  
Shikun He ◽  
Shozo Sonoda ◽  
Mizuki Kitamura ◽  
Christine Spee ◽  
...  
Keyword(s):  
Growth Factor ◽  
Protein Expression ◽  
Choroidal Neovascularization ◽  
Transforming Growth Factor ◽  
Retinal Pigment ◽  
Small Heat Shock Protein ◽  
Transforming Growth Factor Β ◽  
Wild Type ◽  
Rpe Cells ◽  
Αb Crystallin

Abstract αB-crystallin is a chaperone belonging to the small heat shock protein family. Herein we show attenuation of intraocular angiogenesis in αB-crystallin knockout (αB-crystallin−/−) mice in 2 models of intraocular disease: oxygen-induced retinopathy and laser-induced choroidal neovascularization. Vascular endothelial growth factor A (VEGF-A) mRNA and hypoxia inducible factor-1α protein expression were induced during retinal angiogenesis, but VEGF-A protein expression remained low in αB-crystallin−/− retina versus wild-type mice, whereas VEGF-R2 expression was not affected. Both αB-crystallin and its phosphorylated serine59 formwere expressed, and immunoprecipitation revealed αB-crystallin binding to VEGF-A but not transforming growth factor-β in cultured retinal pigment epithelial (RPE) cells. αB-crystallin and VEGF-A are colocalized in the endoplasmic reticulum in RPE cells under chemical hypoxia. αB-crystallin−/− RPE showed low VEGF-A secretion under serum-starved conditions compared with wild-type cells. VEGF-A is polyubiquitinated in control and αB-crystallin siRNA treated RPE; however, mono-tetra ubiquitinated VEGF-A increases with αB-crystallin knockdown. Endothelial cell apoptosis in newly formed vessels was greater in αB-crystallin−/− than wild-type mice. Proteasomal inhibition in αB-crystallin−/− mice partially restores VEGF-A secretion and angiogenic phenotype in choroidal neovascularization. Our studies indicate an important role for αB-crystallin as a chaperone for VEGF-A in angiogenesis and its potential as a therapeutic target.

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