Insoluble Deposits Research Articles

3D compartmented model to study the neurite-related toxicity of Aβ aggregates included in collagen gels of adaptable porosity

Insoluble deposits of β-amyloid (Aβ) are associated to neurodegenerative pathologies, in particular Alzheimer’s Disease (AD). The toxicity of synthetic amyloid-like peptides has been largely demonstrated and shown to depend upon their aggregation state. However, standard 2D cell culture conditions are not well suited to study the role of the close vicinity of Aβ aggregates and growing neurites in the degenerative process. Here, we have designed a compartmented set-up where model neural cells are differentiated on the surface of Aβ-containing collagen matrices. The average pore size can be modulated, from below 0.2μm to more than 0.5μm by simple treatment with collagenase, to respectively hamper or permit neurite outgrowth towards the depth of the matrix. Dense Aβ aggregates (Congo red and ThT-positive) were obtained inside the collagen matrix with a homogeneous distribution and dimensions similar to those observed in post-mortem brain slices from Alzheimer’s patients. The aggregates are not toxic to cells when the pore size is small, in spite of relatively high concentrations of 0.05–0.62mg of peptide per gram of collagen (equivalent to 11.3–113μM). In contrast, on Aβ-containing matrices with large pores, massive neural death is observed when the cells are seeded in the same conditions. It is the first time to our knowledge that Aβ aggregates with a typical morphology of dense plaques are obtained within a porous biomimetic matrix, and are shown to be toxic only when accessible to differentiating cells. Statement of SignificanceInsoluble deposits of β-amyloid (Aβ) are associated to neurodegenerative pathologies, in particular Alzheimer’s Disease (AD). In this study, we have formed Aβ aggregates directly inside a biomimetic collagen matrix loaded with growth factors to induce the differentiation of PC12 or SH-SY6Y cells. For the first time, we show that when the contact between cells and Aβ aggregates is allowed by opening up the matrix porosity, the close vicinity with aggregates induces neurite dystrophy. The compartmented 3D culture model developed and used in this study is a valuable tool to study the cytotoxicity of preformed dense Aβ aggregates and proves that contact between the aggregates and neurons is required to induce neurodegenerative processes.

Abstract A27: Zeb1 induces LOXL2-mediated collagen stabilization and deposition in the extracellular matrix to drive lung cancer invasion and metastasis

Abstract Introduction: Lung cancer is the leading cause of cancer-related death, primarily due to distant metastatic disease. Metastatic cancer cells undergo an epithelial-to-mesenchymal transition (EMT) regulated by a double-negative feedback loop between the microRNA-200 (miR-200) family and Zeb1, but the precise mechanisms of Zeb1-dependent EMT in promoting malignancy remain largely undefined. While the cell-intrinsic effects of EMT are important for tumor progression, the reciprocal dynamic crosstalk between mesenchymal cancer cells and the extracellular matrix (ECM) is equally critical in regulating invasion and metastasis. This study investigates the collaborative effect of EMT and ECM in the metastatic process. Methods: Bioinformatic analysis of TCGA dataset was done to correlate ECM-associated gene expression with EMT gene signature scores. Western blotting and qPCR analysis of epithelial and mesenchymal lung cancer cell lines were performed to determine expression levels of collagen, LOX, and LOXL2. Lung tumor tissues from non-metastatic KrasG12D and metastatic KrasG12D;p53R172H mutant mice were analyzed by immunohistochemistry, Masson's trichrome staining, and second harmonics generation for collagen, LOX, and LOXL2 expression as well as collagen fiber organization. Syngeneic primary tumors generated by subcutaneous injection of murine lung cancer cell lines were analyzed in a similar fashion. Promoter and 3′-UTR luciferase reporter assays were performed to determine direct regulation LOXL2 and LOX by Zeb1 and miR-200, respectively. Results: Our results reveal increased collagen deposition in metastatic tumor tissues as a direct consequence of amplified collagen gene expression in Zeb1-activated mesenchymal lung cancer cells. Additionally, collagen fibers in metastatic lung tumors exhibit greater linearity and organization as a result of collagen crosslinking by the lysyl oxidase (LOX) family of enzymes. Expression of the LOX and LOXL2 isoforms is directly regulated by miR-200 and Zeb1, respectively, and their upregulation in metastatic tumors and mesenchymal cell lines is coordinated to that of collagen. Functionally, LOXL2, as opposed to LOX, is the principle isoform driving lung cancer metastasis by crosslinking and stabilizing insoluble collagen deposition in primary tumor tissues. Conclusions: Our study demonstrates that mesenchymal lung cancer cells metastasize by modulating the compositional and structural properties of the ECM through LOXL-mediated collagen crosslinking and deposition. We are the first to validate direct regulation of LOX and LOXL2 by the miR-200/Zeb1 axis, delineate collagen as a prognostic marker for lung cancer, and identify LOXL2 as a potential therapeutic target against tumor progression. Citation Format: David H. Peng, Pan Tong, Lauren A. Byers, Jing Wang, Chad J. Creighton, Don L. Gibbons. Zeb1 induces LOXL2-mediated collagen stabilization and deposition in the extracellular matrix to drive lung cancer invasion and metastasis. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Metastasis; 2015 Nov 30-Dec 3; Austin, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(7 Suppl):Abstract nr A27.

SR-XRD in situ monitoring of copper-IUD corrosion in simulated uterine fluid using a portable spectroelectrochemical cell

The objective of this work is to study the initial corrosion of copper in the presence of gold when placed in simulated uterine fluid in order to better understand the evolution of active components of copper-IUDs. In order to carry out this study, a portable cell was designed to partially simulate the uterine environment and provide a way of tracking the chemical changes occurring in the samples in situ within a controlled environment over a long period of time using synchrotron spectroelectrochemistry. The dynamically forming crystalline corrosion products are determined in situ for a range of copper–gold surface ratios over the course of a 10-day experiment in the cell. It is concluded that the insoluble deposits forming over this time are not the origin of the anticonception mechanism.

In vivo corrosion behaviour of magnesium alloy in association with surrounding tissue response in rats

Biodegradable magnesium (Mg) alloys are the most promising candidates for osteosynthesis devices. However, their in vivo corrosion behaviour has not been fully elucidated. The aim of this study was to clarify the influence of the physiological environment surrounding Mg alloys on their corrosion behaviour. A Mg–1.0Al alloy with a fine-grained structure was formed into plates using titanium (Ti) as a control. These plates were implanted into the subperiosteum in the head, subcutaneous tissue of the back, and in the muscle of the femur of rats for 1, 2 and 4 weeks. The volumes of the remaining Mg alloy and of the insoluble salt deposition and gas cavities around the Mg alloy were determined by microtomography, and the volume losses were calculated. Then, the tissue response around the plates in each implantation site was examined histopathologically, and its relation to the respective volume loss was analyzed. These analyses determined that the Mg alloy was corroded fastest in the head, at an intermediate level in the back, and slowest in the femur. The insoluble salt deposition at the Mg alloy surface had no influence on the volume loss. Gas cavities formed around the Mg alloy at all implantation sites and decreased after 4 weeks. Histopathological examination revealed that the Mg alloy exhibited good biocompatibility, as was seen with Ti. In addition, vascularized fibrous capsules formed around the plates and became mature with time. Notably, the volume loss in the different anatomical locations correlated with capsule thickness. Together, our results suggest that, to facilitate the successful clinical application of Mg alloys, it will be necessary to further comprehend their interactions with specific in vivo environments.

Protective Effect of Amyloid-β Peptides Against Herpes Simplex Virus-1 Infection in a Neuronal Cell Culture Model.

Senile amyloid plaques are one of the main hallmarks of Alzheimer's disease (AD). They correspond to insoluble deposits of amyloid-β peptides (Aβ) and are responsible for the inflammatory response and neurodegeneration that lead to loss of memory. Recent data suggest that Aβ possess antimicrobial and anti-viral activity in vitro. Here, we have used cocultures of neuroglioma (H4) and glioblastoma (U118-MG) cells as a minimal in vitro model to investigate whether Aβ is produced by neuroglioma cells and whether this could result in protective anti-viral activity against HSV-1 infection. Results showed that H4 cells secreted Aβ42 in response to HSV-1 challenge and that U118-MG cells could rapidly internalize Aβ42. Production of pro-inflammatory cytokines TNFα and IL-1β by H4 and U118-MG cells occurred under basal conditions but infection of the cells with HSV-1 did not significantly upregulate production. Both cell lines produced low levels of IFNα. However, extraneous Aβ42 induced strong production of these cytokines. A combination of Aβ42 and HSV-1 induced production of pro-inflammatory cytokines TNFα and IL-1β, and IFNα in the cell lines. The reported anti-viral protection of Aβ42 was revealed in transfer experiments involving conditioned medium (CM) of HSV-1-infected H4 cells. CM conferred Aβ-dependent protection against HSV-1 replication in de novo cultures of H4 cells challenged with HSV-1. Type 1 interferons did not play a role in these assays. Our data established that H4 neuroglioma cells produced Aβ42 in response to HSV-1 infection thus inhibiting secondary replication. This mechanism may play a role in the etiology of AD.

Profilin Binding Modulates the Aggregation and Phase Separation of Huntingtin N-Terminal Fragments via Polyphasic Linkage

Neurotoxic aggregates formed by N-terminal fragments of the mutant huntingtin protein (Htt-NTFs) are associated with the onset and progression of Huntington's disease. Htt-NTFs encompass expanded polyglutamine (polyQ) tracts that are flanked on the N-terminus by a 17-residue stretch and on the C-terminus by a 38-residue proline-rich stretch (C38). Htt-NTF aggregation and toxicity in cells is diminished by direct interactions with profilin, which is an abundant actin-binding protein that also binds polyproline ligands through a distinct binding site.Htt-NTF aggregation leads to the formation of soluble spherical aggregates (30-50 nm in diameter) and insoluble fibrillar deposits. These aggregates constitute distinct phases and are characterized by saturation concentrations, i.e., threshold concentrations that must be crossed in order for the corresponding phases to form. Using a combination of in vitro measurements we have demonstrated that profilin binding lowers the driving forces for Htt-NTF aggregation and phase separation via polyphasic linkage, a phenomenon whereby distinct saturation concentrations are shifted upwards by an order of magnitude. Accordingly, in the presence of profilin, a higher total concentration of Htt-NTFs is required to cross a given phase boundary. Our binding assays reveal that profilin binds preferentially to Htt-NTF monomers and small soluble oligomers. This involves specific interactions between profilin and the polyproline modules of C38 and possibly non-specific interactions between profilin and polyQ via an avidity effect.Our data provide a biophysical explanation for the observed cellular effects of profilin on Htt-NTF aggregation. Increases in saturation concentrations through polyphasic linkage might be a general mechanism for lowering the driving forces for aggregation and phase separation of aggregation-prone proteins, and may contribute to the protein homeostasis mechanisms used by cells to cope with protein aggregation stress.

Intrinsically Disordered Proteins in Neurodegeneration

Intrinsically disordered proteins (IDPs) have gained wide recognition due to their versatile roles in cell physiology and pathology. A large repertoire of IDPs has been implicated in numerous diseases, making them potential targets for therapeutic intervention. An IDP, which plays a crucial role in a variety of neurodegenerative diseases, is the protein Tau. As a microtubule-associated protein, Tau regulates the assembly and dynamics of microtubules. In the brain of Alzheimer disease patients, Tau is hyperphosphorylated and insoluble deposits of Tau correlate with disease progression. Using NMR spectroscopy as the primary tool we have studied the dynamic ensemble of conformations of Tau in solution, the modulation of dynamic Tau structure by phosphorylation, the structure of Tau aggregates, the mechanism of Tau aggregation inhibitors as well as the interaction of Tau with microtubules and molecular chaperones. To this end we developed improved methods for NMR resonance assignment and ensemble determination. In this presentation I will present recent progress in our understanding of the structural polymorphism of Tau.

Studying Coxiella burnetii Type IV Substrates in the Yeast Saccharomyces cerevisiae: Focus on Subcellular Localization and Protein Aggregation.

Coxiella burnetii is a Gram-negative obligate parasitic bacterium that causes the disease Q-fever in humans. To establish its intracellular niche, it utilizes the Icm/Dot type IVB secretion system (T4BSS) to inject protein effectors into the host cell cytoplasm. The host targets of most cognate and candidate T4BSS-translocated effectors remain obscure. We used the yeast Saccharomyces cerevisiae as a model to express and study six C. burnetii effectors, namely AnkA, AnkB, AnkF, CBU0077, CaeA and CaeB, in search for clues about their role in C. burnetii virulence. When ectopically expressed in HeLa cells, these effectors displayed distinct subcellular localizations. Accordingly, GFP fusions of these proteins produced in yeast also decorated distinct compartments, and most of them altered cell growth. CaeA was ubiquitinated both in yeast and mammalian cells and, in S. cerevisiae, accumulated at juxtanuclear quality-control compartments (JUNQs) and insoluble protein deposits (IPODs), characteristic of aggregative or misfolded proteins. AnkA, which was not ubiquitinated, accumulated exclusively at the IPOD. CaeA, but not AnkA or the other effectors, caused oxidative damage in yeast. We discuss that CaeA and AnkA behavior in yeast may rather reflect misfolding than recognition of conserved targets in the heterologous system. In contrast, CBU0077 accumulated at vacuolar membranes and abnormal ER extensions, suggesting that it interferes with vesicular traffic, whereas AnkB associated with the yeast nucleolus. Both effectors shared common localization features in HeLa and yeast cells. Our results support the idea that C. burnetii T4BSS effectors manipulate multiple host cell targets, which can be conserved in higher and lower eukaryotic cells. However, the behavior of CaeA and AnkA prompt us to conclude that heterologous protein aggregation and proteostatic stress can be a limitation to be considered when using the yeast model to assess the function of bacterial effectors.

Effect of organic carbon and metal accumulation on the bacterial communities in sulphidogenic sediments.

A unique geochemical setting in Lake Cadagno, Switzerland, has led to the accumulation of insoluble metal sulphides in the sedimentary record as the result of past airborne pollution. This offers an exceptional opportunity to study the effect of these metals on the bacterial communities in sediments, and in particular to investigate further the link between metal contamination and an increase in the populations of endospore-forming bacteria observed previously in other metal-contaminated sediments. A decrease in organic carbon and total bacterial counts was correlated with an increase in the numbers of endospores in the oldest sediment samples, showing the first environmental evidence of a decrease in nutrient availability as a trigger of sporulation. Proteobacteria and Firmicutes were the two dominant bacterial phyla throughout the sediment, the former in an area with high sulphidogenic activity, and the latter in the oldest samples. Even though the dominant Firmicutes taxa were stable along the sediment core and did not vary with changes in metal contamination, the prevalence of some molecular species like Clostridium sp. was positively correlated with metal sulphide concentration. However, this cannot be generalized to all endospore-forming species. Overall, the community composition supports the hypothesis of sporulation as the main mechanism explaining the dominance of endospore formers in the deepest part of the sediment core, while metal contamination in the form of insoluble metal sulphide deposits appears not to be linked with sporulation as a mechanism of metal tolerance in this sulphidogenic ecosystem.

Proteasome storage granules are transiently associated with the insoluble protein deposit in Saccharomyces cerevisiae.

Proteasome storage granules (PSGs) are created in yeast as part of an extensive and programmed reorganization of proteins into reversible assemblies upon carbon source depletion. Here, we demonstrate that cells distinguish dysfunctional proteasomes from PSGs on the cytosolic insoluble protein deposit (IPOD). Furthermore, we provide evidence that this is a general mechanism for the reorganization of additional proteins into reversible assemblies. Our study expands the roles of the IPOD, which might serve not only as the specific depository for amyloidogenic and misfolded proteins, but also as a potential hub from which proteins are directed to distinct cellular compartments. These findings therefore provide a framework for understanding how cells discriminate between intact and abnormal proteins under stress conditions to ensure that only structurally 'correct' proteins are deployed.

Poor Outcomes in Hepatic Amyloidosis: A Report of 2 Cases.

Hepatic amyloidosis is a rare disease entity that results from insoluble amyloid protein deposition in the liver. The disease often presents with vague, nonspecific clinical features. Currently, there is little literature describing treatment outcomes for biopsy-proven hepatic amyloidosis and current treatment guidelines recommend that patients enroll in a clinical trial due to insufficient evidence to suggest an optimal treatment regimen. Here, we present two cases of hepatic amyloidosis at an academic medical center and describe their presentation, treatment, and outcomes. These cases highlight the poor outcomes and difficult management of hepatic amyloidosis. Further understanding and investigation of this rare disease are warranted.

A novel curcumin derivative, f-methyl-curcumin-1 (fmec1), is a potential diagnostic and therapeutic agent for Alzheimer's disease.

Event Abstract Back to Event A novel curcumin derivative, f-methyl-curcumin-1 (fmec1), is a potential diagnostic and therapeutic agent for Alzheimer's disease. Ikuo Tooyama1*, Daijiro Yanagisawa1 and Nor Faeizah Ibrahim1 1 Shiga University of Medical Science, Molecular Neuroscience Research Center, Japan Curcumin has various beneficial pharmacological properties such as anti-tumor, anti-oxidative, and anti-inflammatory effects. Also, some recent reports of in vitro and in vivo experiments suggest favorable effects of curcumin in preventing or treating Alzheimer’s disease (AD) pathology. However, the first clinical trial of curcumin on patients with AD showed no effects. Therefore, more effective curcumin analogues may be needed. We recently developed a novel curcumin derivative, 1,7-Bis(4’-hydroxy-3’-trifluoromethoxyphenyl)-4-methoxycarbonylethyl-1,6-heptadiene-3,5-dione (FMeC1) as a fluorine-19 MRI probe to detect amyloid deposition. We present here the effects of our new compounds on Aβ aggregation in vitro and AD pathology in a mouse model of AD. APPswe/PS1dE9 double transgenic mice were fed with a standard lab chow diet with or without curcumin, FMeC1, or FMeC2 (500 ppm which is equivalent to ~1.25 mg/day or 83 mg/kg body weight) for 6 months from 9 months of age. FMeC1-treated mice showed a reduction in insoluble Aβ deposits and glial activation together with reduced cognitive deficits, compared to animals receiving a control diet or with curcumin or FMeC2 in their diet. Quartz crystal microbalance analysis showed that curcumin and FMeC1 bound not only to Aβ aggregates but also to Aβ oligomers, which are responsible for neuronal and synaptic dysfunction in AD. Both curcumin and FMeC1 modulated the formation of Aβ aggregates, but only FMeC1 significantly attenuated the cell toxicity of Aβ. Keywords: Curcumin, Oxidative Stress, Alzheimer, neurodegeneration, antioxidant Conference: 14th Meeting of the Asian-Pacific Society for Neurochemistry, Kuala Lumpur, Malaysia, 27 Aug - 30 Aug, 2016. Presentation Type: Symposium 7: New Insights on Oxidative Stress in Neurodegenerative Diseases and Therapeutic Potential of Anti- Oxidants as a Drug for the Pre-Emptive Medicine Topic: 14th Meeting of the Asian-Pacific Society for Neurochemistry Citation: Tooyama I, Yanagisawa D and Ibrahim N (2016). A novel curcumin derivative, f-methyl-curcumin-1 (fmec1), is a potential diagnostic and therapeutic agent for Alzheimer's disease.. Conference Abstract: 14th Meeting of the Asian-Pacific Society for Neurochemistry. doi: 10.3389/conf.fncel.2016.36.00031 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 26 Jul 2016; Published Online: 11 Aug 2016. * Correspondence: Prof. Ikuo Tooyama, Shiga University of Medical Science, Molecular Neuroscience Research Center, Otsu, Shiga, Japan, kinchan@belle.shiga-med.ac.jp Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Ikuo Tooyama Daijiro Yanagisawa Nor Faeizah Ibrahim Google Ikuo Tooyama Daijiro Yanagisawa Nor Faeizah Ibrahim Google Scholar Ikuo Tooyama Daijiro Yanagisawa Nor Faeizah Ibrahim PubMed Ikuo Tooyama Daijiro Yanagisawa Nor Faeizah Ibrahim Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Metals and Neuronal Metal Binding Proteins Implicated in Alzheimer's Disease.

Alzheimer's disease (AD) is the most prevalent age-related dementia affecting millions of people worldwide. Its main pathological hallmark feature is the formation of insoluble protein deposits of amyloid-β and hyperphosphorylated tau protein into extracellular plaques and intracellular neurofibrillary tangles, respectively. Many of the mechanistic details of this process remain unknown, but a well-established consequence of protein aggregation is synapse dysfunction and neuronal loss in the AD brain. Different pathways including mitochondrial dysfunction, oxidative stress, inflammation, and metal metabolism have been suggested to be implicated in this process. In particular, a body of evidence suggests that neuronal metal ions such as copper, zinc, and iron play important roles in brain function in health and disease states and altered homeostasis and distribution as a common feature across different neurodegenerative diseases and aging. In this focused review, we overview neuronal proteins that are involved in AD and whose metal binding properties may underlie important biochemical and regulatory processes occurring in the brain during the AD pathophysiological process.

Curcumin Attenuates Amyloid-β Aggregate Toxicity and Modulates Amyloid-β Aggregation Pathway.

The abnormal misfolding and aggregation of amyloid-β (Aβ) peptides into β-sheet enriched insoluble deposits initiates a cascade of events leading to pathological processes and culminating in cognitive decline in Alzheimer's disease (AD). In particular, soluble oligomeric/prefibrillar Aβ have been shown to be potent neurotoxins. The naturally occurring polyphenol curcumin has been shown to exert a neuroprotective effect against age-related neurodegenerative diseases such as AD. However, its protective mechanism remains unclear. In this study, we investigated the effects of curcumin on the aggregation of Aβ40 as well as Aβ40 aggregate induced neurotoxicity. Our results show that the curcumin does not inhibit Aβ fibril formation, but rather enriches the population of "off-pathway" soluble oligomers and prefibrillar aggregates that were nontoxic. Curcumin also exerted a nonspecific neuroprotective effect, reducing toxicities induced by a range of Aβ conformers, including monomeric, oligomeric, prefibrillar, and fibrillar Aβ. The neuroprotective effect is possibly membrane-mediated, as curcumin reduced the extent of cell membrane permeabilization induced by Aβ aggregates. Taken together, our study shows that curcumin exerts its neuroprotective effect against Aβ induced toxicity through at least two concerted pathways, modifying the Aβ aggregation pathway toward the formation of nontoxic aggregates and ameliorating Aβ-induced toxicity possibly through a nonspecific pathway.

Experimental and Modeling Studies of Heat Transfer, Fluid Dynamics, and Autoxidation Chemistry in the Jet Fuel Thermal Oxidation Tester (JFTOT)

Modern military aircraft use jet fuel as a coolant before it is burned in the combustor. Prior to combustion, dissolved O2 and trace heteroatomic species react with the heated fuel to form insoluble particles and surface deposits that can impair engine performance. For safe aircraft operation, it is important to minimize jet fuel oxidation and resultant surface deposition in critical fuel system components. ASTM D3241, “Standard Test Method for Thermal Oxidation Stability of Aviation Turbine Fuels” (ASTM International: West Conshohocken, PA, 2014), defines the standard test method for evaluation of the thermal oxidation stability of aviation turbine fuels. The JFTOT is a thermal stability test that measures the tendency for fuel to form deposits via heated tube discoloration and/or an increased pressure drop across an outlet filter. It is used to discriminate between fuels of poor and acceptable thermal stability. However, the fluid dynamics, heat transfer characteristics, extent of oxidation, and corresp...

Systemic control of protein synthesis through sequestration of translation and ribosome biogenesis factors during severe heat stress

Environmental stress causes the sequestration of proteins into insoluble deposits including cytoplasmic stress granules (SGs), containing mRNA and a variety of translation factors. Here we systematically identified proteins sequestered in Saccharomyces cerevisiae at 46°C by a SG co-localization screen and proteomic analysis of insoluble protein fractions. We identified novel SG components including essential aminoacyl-tRNA synthetases. Moreover, we discovered nucleus-associated deposits containing ribosome biogenesis factors. Our study suggests downregulation of cytosolic protein synthesis and nuclear ribosome production at multiple levels through heat shock induced protein sequestrations.

Determinants of amyloid fibril degradation by the PDZ protease HTRA1.

Excessive aggregation of proteins has a major impact on cell fate and is a hallmark of amyloid diseases in humans. To resolve insoluble deposits and to maintain protein homeostasis, all cells use dedicated protein disaggregation, protein folding and protein degradation factors. Despite intense recent research, the underlying mechanisms controlling this key metabolic event are not well understood. Here, we analyzed how a single factor, the highly conserved serine protease HTRA1, degrades amyloid fibrils in an ATP-independent manner. This PDZ protease solubilizes protein fibrils and disintegrates the fibrillar core structure, allowing productive interaction of aggregated polypeptides with the active site for rapid degradation. The aggregate burden in a cellular model of cytoplasmic tau aggregation is thus reduced. Mechanistic aspects of ATP-independent proteolysis and its implications in amyloid diseases are discussed.

Anthocyanin suppresses the toxicity of Aβ deposits through diversion of molecular forms in in vitro and in vivo models of Alzheimer's disease

Objectives: The pathogenesis of Alzheimer's disease (AD) is strongly correlated with the aggregation and deposition of the amyloid beta (Aβ1–42) peptide in fibrillar form, and many studies have shown that plant-derived polyphenols are capable of attenuating AD progression in various disease models. In this study, we set out to correlate the effects of anthocyanoside extracts (Vaccinium myrtillus anthocyanoside (VMA)) obtained from bilberry on the in vitro progression of Aβ fibril formation with the in vivo effects of this compound on AD pathogenesis.Methods: Thioflavin T fluorescence assays and atomic force microscopy were used to monitor Aβ amyloid formation in in vitro assays. Effects of Aβ amyloids on cellular viability were assayed using cultured Neuro2a cells. Cognitive effects were probed using mice that simultaneously expressed mutant human Aβ precursor and mutant presenilin-2.Results: Addition of VMA inhibited the in vitro formation of Aβ peptide fibrils and also reduced the toxicity of these aggregates toward Neuro2a cells. A diet containing 1% VMA prevented the cognitive degeneration in AD mice. Curiously, this diet-derived retention of cognitive ability was not accompanied by a reduction in aggregate deposition in brains; rather, an increase in insoluble deposits was observed compared with mice raised on a control diet.Discussion: The paradoxical increase in insoluble deposits caused by VMA suggests that these polyphenols divert Aβ aggregation to an alternate, non-toxic form. This finding underscores the complex effects that polyphenol compounds may exert on amyloid deposition in vivo.

Aspects of a Distinct Cytotoxicity of Selenium Salts and Organic Selenides in Living Cells with Possible Implications for Drug Design.

Selenium is traditionally considered as an antioxidant element and selenium compounds are often discussed in the context of chemoprevention and therapy. Recent studies, however, have revealed a rather more colorful and diverse biological action of selenium-based compounds, including the modulation of the intracellular redox homeostasis and an often selective interference with regulatory cellular pathways. Our basic activity and mode of action studies with simple selenium and tellurium salts in different strains of Staphylococcus aureus (MRSA) and Saccharomyces cerevisiae indicate that such compounds are sometimes not particularly toxic on their own, yet enhance the antibacterial potential of known antibiotics, possibly via the bioreductive formation of insoluble elemental deposits. Whilst the selenium and tellurium compounds tested do not necessarily act via the generation of Reactive Oxygen Species (ROS), they seem to interfere with various cellular pathways, including a possible inhibition of the proteasome and hindrance of DNA repair. Here, organic selenides are considerably more active compared to simple salts. The interference of selenium (and tellurium) compounds with multiple targets could provide new avenues for the development of effective antibiotic and anticancer agents which may go well beyond the traditional notion of selenium as a simple antioxidant.

An automatic collector to monitor insoluble atmospheric deposition: application for mineral dust deposition

Abstract. Deposition is one of the key terms of the mineral dust cycle. However, dust deposition remains poorly constrained in transport models simulating the atmospheric dust cycle. This is mainly due to the limited number of relevant deposition measurements. This paper aims to present an automatic collector (CARAGA), specially developed to sample the total (dry and wet) atmospheric deposition of insoluble dust in remote areas. The autonomy of the CARAGA can range from 25 days to almost 1 year depending on the programmed sampling frequency (from 1 day to 2 weeks respectively). This collector is used to sample atmospheric deposition of Saharan dust on the Frioul islands in the Gulf of Lions in the Western Mediterranean. To quantify the mineral dust mass in deposition samples, a weighing and ignition protocol is applied. Almost 2 years of continuous deposition measurements performed on a weekly sampling basis on Frioul Island are presented and discussed with air mass trajectories and satellite observations of dust. Insoluble mineral deposition measured on Frioul Island was 2.45 g m−2 for February to December 2011 and 3.16 g m−2 for January to October 2012. Nine major mineral deposition events, measured during periods with significant MODIS aerosol optical depths, were associated with air masses coming from the southern Mediterranean Basin and North Africa.