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Del Río, J. A., Ferrer, Isidre, Gavín, R., (2018). Role of cellular prion protein in interneuronal amyloid transmission Progress in Neurobiology 165-167, 87-102

Several studies have indicated that certain misfolded amyloids composed of tau, β-amyloid or α-synuclein can be transferred from cell to cell, suggesting the contribution of mechanisms reminiscent of those by which infective prions spread through the brain. This process of a ‘prion-like’ spreading between cells is also relevant as a novel putative therapeutic target that could block the spreading of proteinaceous aggregates throughout the brain which may underlie the progressive nature of neurodegenerative diseases. The relevance of β-amyloid oligomers and cellular prion protein (PrPC) binding has been a focus of interest in Alzheimer’s disease (AD). At the molecular level, β-amyloid/PrPC interaction takes place in two differently charged clusters of PrPC. In addition to β-amyloid, participation of PrPC in α-synuclein binding and brain spreading also appears to be relevant in α-synucleopathies. This review summarizes current knowledge about PrPC as a putative receptor for amyloid proteins and the physiological consequences of these interactions..

Keywords: Cellular prion protein, Amyloid, Proteinaceous species, ‘prion-like’ spreading, Spreading, Neurodegeneration


Urrea, L., Segura, Miriam, Masuda-Suzukake, M., Hervera, A., Pedraz, L., Aznar, J. M. G., Vila, M., Samitier, J., Torrents, E., Ferrer, Isidro, Gavín, R., Hagesawa, M., Del Río, J. A., (2018). Involvement of cellular prion protein in α-synuclein transport in neurons Molecular Neurobiology 55, (3), 1847-1860

The cellular prion protein, encoded by the gene Prnp, has been reported to be a receptor of β-amyloid. Their interaction is mandatory for neurotoxic effects of β-amyloid oligomers. In this study, we aimed to explore whether the cellular prion protein participates in the spreading of α-synuclein. Results demonstrate that Prnp expression is not mandatory for α-synuclein spreading. However, although the pathological spreading of α-synuclein can take place in the absence of Prnp, α-synuclein expanded faster in PrPC-overexpressing mice.

Keywords: Amyloid spreading, Microfluidic devices, Prnp, Synuclein


Pallarès, Irantzu, de Groot, Natalia S., Iglesias, Valentín, Sant'Anna, Ricardo, Biosca, Arnau, Fernàndez-Busquets, Xavier, Ventura, Salvador, (2018). Discovering putative prion-like proteins in Plasmodium falciparum: A computational and experimental analysis Frontiers in Microbiology 9, Article 1737

Prions are a singular subset of proteins able to switch between a soluble conformation and a self-perpetuating amyloid state. Traditionally associated with neurodegenerative diseases, increasing evidence indicates that organisms exploit prion-like mechanisms for beneficial purposes. The ability to transit between conformations is encoded in the so-called prion domains, long disordered regions usually enriched in glutamine/asparagines residues. Interestingly, Plasmodium falciparum, the parasite that causes the most virulent form of malaria, is exceptionally rich in proteins bearing long Q/N-rich sequence stretches, accounting for roughly 30% of the proteome. This biased composition suggests that these protein regions might correspond to prion-like domains (PrLDs) and potentially form amyloid assemblies. To investigate this possibility, we performed a stringent computational survey for Q/N-rich PrLDs on P. falciparum. Our data indicate that ~10% of P. falciparum protein sequences have prionic signatures, and that this subproteome is enriched in regulatory proteins, such as transcription factors and RNA-binding proteins. Furthermore, we experimentally demonstrate for several of the identified PrLDs that, despite their disordered nature, they contain inner short sequences able to spontaneously self-assemble into amyloid-like structures. Although the ability of these sequences to nucleate the conformational conversion of the respective full-length proteins should still be demonstrated, our analysis suggests that, as previously described for other organisms, prion-like proteins might also play a functional role in P. falciparum.

Keywords: Plasmodium, Protein aggregation, Amyloid, Prion, Q-N-rich sequences, Protein Disorder


Valls-Comamala, V., Guivernau, B., Bonet, J., Puig, M., Perálvarez-Marín, A., Palomer, E., Fernàndez-Busquets, X., Altafaj, X., Tajes, M., Puig-Pijoan, A., Vicente, R., Oliva, B., Muñoz, F. J., (2017). The antigen-binding fragment of human gamma immunoglobulin prevents amyloid β-peptide folding into β-sheet to form oligomers Oncotarget 8, (25), 41154-41165

The amyloid beta-peptide (Aβ) plays a leading role in Alzheimer’s disease (AD) physiopathology. Even though monomeric forms of Aβ are harmless to cells, Aβ can aggregate into β-sheet oligomers and fibrils, which are both neurotoxic. Therefore, one of the main therapeutic approaches to cure or delay AD onset and progression is targeting Aβ aggregation. In the present study, we show that a pool of human gamma immunoglobulins (IgG) protected cortical neurons from the challenge with Aβ oligomers, as assayed by MTT reduction, caspase-3 activation and cytoskeleton integrity. In addition, we report the inhibitory effect of IgG on Aβ aggregation, as shown by Thioflavin T assay, size exclusion chromatography and atomic force microscopy. Similar results were obtained with Palivizumab, a human anti-sincitial virus antibody. In order to dissect the important domains, we cleaved the pool of human IgG with papain to obtain Fab and Fc fragments. Using these cleaved fragments, we functionally identified Fab as the immunoglobulin fragment inhibiting Aβ aggregation, a result that was further confirmed by an in silico structural model. Interestingly, bioinformatic tools show a highly conserved structure able to bind amyloid in the Fab region. Overall, our data strongly support the inhibitory effect of human IgG on Aβ aggregation and its neuroprotective role.

Keywords: Alzheimer’s disease, Amyloid, Immunoglobulin, Fab, Oligomers


Garcia-Esparcia, Paula, López-González, Irene, Grau-Rivera, Oriol, García-Garrido, María Francisca, Konetti, Anusha, Llorens, Franc, Zafar, Saima, Carmona, Margarita, del Rio, José Antonio, Zerr, Inga, Gelpi, Ellen, Ferrer, Isidro, (2017). Dementia with Lewy Bodies: Molecular pathology in the frontal cortex in typical and rapidly progressive forms Frontiers in Neurology 8, Article 89

Objectives: The goal of this study was to assess mitochondrial function, energy, and purine metabolism, protein synthesis machinery from the nucleolus to the ribosome, inflammation, and expression of newly identified ectopic olfactory receptors (ORs) and taste receptors (TASRs) in the frontal cortex of typical cases of dementia with Lewy bodies (DLB) and cases with rapid clinical course (rpDLB: 2 years or less) compared with middle-aged non-affected individuals, in order to learn about the biochemical abnormalities underlying Lewy body pathology. Methods: Real-time quantitative PCR, mitochondrial enzymatic assays, and analysis of β-amyloid, tau, and synuclein species were used. Results: The main alterations in DLB and rpDLB, which are more marked in the rapidly progressive forms, include (i) deregulated expression of several mRNAs and proteins of mitochondrial subunits, and reduced activity of complexes I, II, III, and IV of the mitochondrial respiratory chain; (ii) reduced expression of selected molecules involved in energy metabolism and increased expression of enzymes involved in purine metabolism; (iii) abnormal expression of nucleolar proteins, rRNA18S, genes encoding ribosomal proteins, and initiation factors of the transcription at the ribosome; (iv) discrete inflammation; and (v) marked deregulation of brain ORs and TASRs, respectively. Severe mitochondrial dysfunction involving activity of four complexes, minimal inflammatory responses, and dramatic altered expression of ORs and TASRs discriminate DLB from Alzheimer’s disease. Altered solubility and aggregation of α-synuclein, increased β-amyloid bound to membranes, and absence of soluble tau oligomers are common in DLB and rpDLB. Low levels of soluble β-amyloid are found in DLB. However, increased soluble β-amyloid 1–40 and β-amyloid 1–42, and increased TNFα mRNA and protein expression, distinguish rpDLB. Conclusion: Molecular alterations in frontal cortex in DLB involve key biochemical pathways such as mitochondria and energy metabolism, protein synthesis, purine metabolism, among others and are accompanied by discrete innate inflammatory response.

Keywords: Dementia with Lewy bodies, Alzheimer’s disease, α-synuclein, Mitochondria, Protein synthesis, Inflammation, β-amyloid, Olfactory receptors


Guivernau, B., Bonet, J., Valls-Comamala, V., Bosch-Morató, M., Godoy, J. A., Inestrosa, N. C., Perálvarez-Marín, A., Fernàndez-Busquets, X., Andreu, D., Oliva, B., Muñoz, F. J., (2016). Amyloid-β peptide nitrotyrosination stabilizes oligomers and enhances NMDAR-mediated toxicity Journal of Neuroscience , 36, (46), 11693-11703

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the pathological aggregation of the amyloid-β peptide (Aβ). Monomeric soluble Aβ can switch from helicoidal to β-sheet conformation, promoting its assembly into oligomers and subsequently to amyloid fibrils. Oligomers are highly toxic to neurons and have been reported to induce synaptic transmission impairments. The progression from oligomers to fibrils forming senile plaques is currently considered a protective mechanism to avoid the presence of the highly toxic oligomers. Protein nitration is a frequent post-translational modification under AD nitrative stress conditions. Aβ can be nitrated at tyrosine 10 (Y10) by peroxynitrite. Based on our analysis of ThT binding, Western blot and electron and atomic force microscopy, we report that Aβ nitration stabilizes soluble, highly toxic oligomers and impairs the formation of fibrils. We propose a mechanism by which fibril elongation is interrupted upon Y10 nitration: Nitration disrupts fibril-forming folds by preventing H14-mediated bridging, as shown with an Aβ analog containing a single residue (H to E) replacement that mimics the behavior of nitrated Aβ related to fibril formation and neuronal toxicity. The pathophysiological role of our findings in AD was highlighted by the study of these nitrated oligomers on mouse hippocampal neurons, where an increased NMDAR-dependent toxicity of nitrated Aβ oligomers was observed. Our results show that Aβ nitrotyrosination is a post-translational modification that increases Aβ synaptotoxicity.

Keywords: Alzheimer, Amyloid, Nitrotyrosination, NMDA Rc, Oligomers, Peroxynitrite


Tahirbegi, I.B., Pardo, W.A., Alvira, M., Mir, M., Samitier, J., (2016). Amyloid Aβ 42, a promoter of magnetite nanoparticle formation in Alzheimer's disease Nanotechnology 27, (46), 465102

The accumulation of iron oxides - mainly magnetite - with amyloid peptide is a key process in the development of Alzheimer's disease (AD). However, the mechanism for biogeneration of magnetite inside the brain of someone with AD is still unclear. The iron-storing protein ferritin has been identified as the main magnetite-storing molecule. However, accumulations of magnetite in AD are not correlated with an increase in ferritin, leaving this question unresolved. Here we demonstrate the key role of amyloid peptide Aβ 42, one of the main hallmarks of AD, in the generation of magnetite nanoparticles in the absence of ferritin. The capacity of amyloid peptide to bind and concentrate iron hydroxides, the basis for the formation of magnetite, benefits the spontaneous synthesis of these nanoparticles, even under unfavorable conditions for their formation. Using scanning and transmission electron microscopy, electron energy loss spectroscopy and magnetic force microscopy we characterized the capacity of amyloid peptide Aβ 42 to promote magnetite formation.

Keywords: Alzheimer disease (AD), amyloid peptide Ab42, magnetite nanoparticle, metallobiomolecule, iron oxide, neurodegenerative brain diseases


Moles, Ernest, Valle-Delgado, Juan José, Urbán, Patricia, Azcárate, Isabel G., Bautista, José M., Selva, Javier, Egea, Gustavo, Ventura, Salvador, Fernàndez-Busquets, Xavier, (2015). Possible roles of amyloids in malaria pathophysiology Future Science OA , 1, (2), FSO43

The main therapeutic and prophylactic tools against malaria have been locked for more than a century in the classical approaches of using drugs targeting metabolic processes of the causing agent, the protist Plasmodium spp., and of designing vaccines against chosen antigens found on the parasite’s surface. Given the extraordinary resources exhibited by Plasmodium to escape these traditional strategies, which have not been able to free humankind from the scourge of malaria despite much effort invested in them, new concepts have to be explored in order to advance toward eradication of the disease. In this context, amyloid-forming proteins and peptides found in the proteome of the pathogen should perhaps cease being regarded as mere anomalous molecules. Their likely functionality in the pathophysiology of Plasmodium calls for attention being paid to them as a possible Achilles’ heel of malaria. Here we will give an overview of Plasmodium-encoded amyloid-forming polypeptides as potential therapeutic targets and toxic elements, particularly in relation to cerebral malaria and the blood–brain barrier function. We will also discuss the recent finding that the genome of the parasite contains an astonishingly high proportion of prionogenic domains.

Keywords: Amyloids, Intrinsically unstructured proteins, Malaria, Prions


Ramos-Fernández, E., Tajes, M., Palomer, E., Ill-Raga, G., Bosch-Morató, M., Guivernau, B., Román-Dégano, I., Eraso-Pichot, A., Alcolea, D., Fortea, J., Nuñez, L., Paez, A., Alameda, F., Fernàndez-Busquets, X., Lleó, A., Elosúa, R., Boada, M., Valverde, M. A., Muñoz, F. J., (2014). Posttranslational nitro-glycative modifications of albumin in Alzheimer's disease: Implications in cytotoxicity and amyloid-β peptide aggregation Journal of Alzheimer's Disease , 40, (3), 643-657

Glycation and nitrotyrosination are pathological posttranslational modifications that make proteins prone to losing their physiological properties. Since both modifications are increased in Alzheimer's disease (AD) due to amyloid-β peptide (Aβ) accumulation, we have studied their effect on albumin, the most abundant protein in cerebrospinal fluid and blood. Brain and plasmatic levels of glycated and nitrated albumin were significantly higher in AD patients than in controls. In vitro turbidometry and electron microscopy analyses demonstrated that glycation and nitrotyrosination promote changes in albumin structure and biochemical properties. Glycated albumin was more resistant to proteolysis and less uptake by hepatoma cells occurred. Glycated albumin also reduced the osmolarity expected for a solution containing native albumin. Both glycation and nitrotyrosination turned albumin cytotoxic in a cell type-dependent manner for cerebral and vascular cells. Finally, of particular relevance to AD, these modified albumins were significantly less effective in avoiding Aβ aggregation than native albumin. In summary, nitrotyrosination and especially glycation alter albumin structural and biochemical properties, and these modifications might contribute for the progression of AD.

Keywords: Albumin, Alzheimer's disease, amyloid, glycation, nitrotyrosination, oxidative stress


Ordoñez-Gutiérrez, L., Torres, J. M., Gavín, R., Antón, M., Arroba-Espinosa, A. I., Espinosa, J. C., Vergara, C., del Río, J. A., Wandosell, F., (2013). Cellular prion protein modulates β-amyloid deposition in aged APP/PS1 transgenic mice Neurobiology of Aging , 34, (12), 2793-2804

Alzheimer's disease and prion diseases are neuropathological disorders that are caused by abnormal processing and aggregation of amyloid and prion proteins. Interactions between amyloid precursor protein (APP) and PrPc proteins have been described at the neuron level. Accordingly to this putative interaction, we investigated whether β-amyloid accumulation may affect prion infectivity and, conversely, whether different amounts of PrP may affect β-amyloid accumulation. For this purpose, we used the APPswe/PS1dE9 mouse line, a common model of Alzheimer's disease, crossed with mice that either overexpress (Tga20) or that lack prion protein (knock-out) to generate mice that express varying amounts of prion protein and deposit β-amyloid. On these mouse lines, we investigated the influence of each protein on the evolution of both diseases. Our results indicated that although the presence of APP/PS1 and β-amyloid accumulation had no effect on prion infectivity, the accumulation of β-amyloid deposits was dependent on PrPc, whereby increasing levels of prion protein were accompanied by a significant increase in β-amyloid aggregation associated with aging.

Keywords: Aging, Amyloid, Neurodegeneration, Prion, Signaling


Mir, Mònica , Tahirbegi, Islam Bogachan , Valle-Delgado, Juan José , Fernàndez-Busquets, X., Samitier, Josep , (2012). In vitro study of magnetite-amyloid β complex formation Nanomedicine: Nanotechnology, Biology, and Medicine 8, (6), 974-980

Biogenic magnetite (Fe3O4) has been identified in human brain tissue. However, abnormal concentration of magnetite nanoparticles in the brain has been observed in different neurodegenerative pathologies. In the case of Alzheimer's disease (AD), these magnetic nanoparticles have been identified attached to the characteristic brain plaques, which are mainly formed by fibrils of amyloid β peptide (Aβ). However, few clues about the formation of the magnetite-Aβ complex have been reported. We have investigated the interaction between these important players in the AD with superconducting quantum interference, scanning electron microscope, surface plasmon resonance, and magnetic force microscopy. The results support the notion that the magnetite-Aβ complex is created before the synthesis of the magnetic nanoparticles, bringing a highly stable interaction of this couple.

Keywords: Alzheimer's disease, Biogenic magnetite, Amyloid β peptide (Aβ), Superconducting quantum interference, Scanning electron microscope, Surface plasmon resonance, Magnetic force microscopy


Arimon, M., Sanz, F., Giralt, E., Carulla, N., (2012). Template-assisted lateral growth of amyloid-β42 fibrils studied by differential labeling with gold nanoparticles Bioconjugate Chemistry , 23, (1), 27-32

Amyloid-β protein (Aβ) aggregation into amyloid fibrils is central to the origin and development of Alzheimer’s disease (AD), yet this highly complex process is poorly understood at the molecular level. Extensive studies have shown that Aβ fibril growth occurs through fibril elongation, whereby soluble molecules add to the fibril ends. Nevertheless, fibril morphology strongly depends on aggregation conditions. For example, at high ionic strength, Aβ fibrils laterally associate into bundles. To further study the mechanisms leading to fibril growth, we developed a single-fibril growth assay based on differential labeling of two Aβ42 variants with gold nanoparticles. We used this assay to study Aβ42 fibril growth under different conditions and observed that bundle formation is preceded by lateral interaction of soluble Aβ42 molecules with pre-existing fibrils. Based on this data, we propose template-assisted lateral fibril growth as an additional mechanism to elongation for Aβ42 fibril growth.

Keywords: AFM, Beta-Amyloid Fibrils, Polymorphism, Association, Elongation, Dynamics, State


Valle-Delgado, J. J., Liepina, I., Lapidus, D., Sabaté, R., Ventura, S., Samitier, J., Fernàndez-Busquets, X., (2012). Self-assembly of human amylin-derived peptides studied by atomic force microscopy and single molecule force spectroscopy Soft Matter , 8, (4), 1234-1242

The self-assembly of peptides and proteins into amyloid fibrils of nanometric thickness and up to several micrometres in length, a phenomenon widely observed in biological systems, has recently aroused a growing interest in nanotechnology and nanomedicine. Here we have applied atomic force microscopy and single molecule force spectroscopy to study the amyloidogenesis of a peptide derived from human amylin and of its reverse sequence. The spontaneous formation of protofibrils and their orientation along well-defined directions on graphite and DMSO-coated graphite substrates make the studied peptides interesting candidates for nanotechnological applications. The measured binding forces between peptides correlate with the number of hydrogen bonds between individual peptides inside the fibril structure according to molecular dynamics simulations.

Keywords: Amyloid fibril, Amyloidogenesis, Binding forces, Fibril structure, Graphite substrate, Molecular dynamics simulations, Nanometrics, Protofibrils, Single molecule force spectroscopy, Spontaneous formation, Atomic force microscopy, Atomic spectroscopy, Graphite, Hydrogen bonds, Medical nanotechnology, Molecular dynamics, Molecular physics, Self assembly, Thickness measurement, Peptides


Villar-Pique, A., De Groot, N. S., Sabaté, R., Acebrón, S. P., Celaya, G., Fernàndez-Busquets, X., Muga, A., Ventura, S., (2012). The effect of amyloidogenic peptides on bacterial aging correlates with their intrinsic aggregation propensity Journal of Molecular Biology , 421, (2-3), 270-281

The formation of aggregates by misfolded proteins is thought to be inherently toxic, affecting cell fitness. This observation has led to the suggestion that selection against protein aggregation might be a major constraint on protein evolution. The precise fitness cost associated with protein aggregation has been traditionally difficult to evaluate. Moreover, it is not known if the detrimental effect of aggregates on cell physiology is generic or depends on the specific structural features of the protein deposit. In bacteria, the accumulation of intracellular protein aggregates reduces cell reproductive ability, promoting cellular aging. Here, we exploit the cell division defects promoted by the intracellular aggregation of Alzheimer's-disease-related amyloid β peptide in bacteria to demonstrate that the fitness cost associated with protein misfolding and aggregation is connected to the protein sequence, which controls both the in vivo aggregation rates and the conformational properties of the aggregates. We also show that the deleterious impact of protein aggregation on bacterial division can be buffered by molecular chaperones, likely broadening the sequential space on which natural selection can act. Overall, the results in the present work have potential implications for the evolution of proteins and provide a robust system to experimentally model and quantify the impact of protein aggregation on cell fitness.

Keywords: Amyloid fibrils, Chaperones, Escherichia coli, Inclusion bodies, Protein aggregation


Valle-Delgado, J. J., Alfonso-Prieto, M., de Groot, N. S., Ventura, S., Samitier, J., Rovira, C., Fernàndez-Busquets, X., (2010). Modulation of A beta(42) fibrillogenesis by glycosaminoglycan structure FASEB Journal , 24, (11), 4250-4261

The role of amyloid beta (A beta) peptide in the onset and progression of Alzheimer's disease is linked to the presence of soluble A beta species. Sulfated glycosaminoglycans (GAGs) promote A beta fibrillogenesis and reduce the toxicity of the peptide in neuronal cell cultures, but a satisfactory rationale to explain these effects at the molecular level has not been provided yet. We have used circular dichroism, Fourier transform infrared spectroscopy, fluorescence microscopy and spectroscopy, protease digestion, atomic force microscopy (AFM), and molecular dynamics simulations to characterize the association of the 42-residue fragment A beta(42) with sulfated GAGs, hyaluronan, chitosan, and poly(vinyl sulfate) (PVS). Our results indicate that the formation of stable A beta(42) fibrils is promoted by polymeric GAGs with negative charges placed in-frame with the 4.8-angstrom separating A beta(42) monomers within protofibrillar beta-sheets. Incubation of A beta(42) with excess sulfated GAGs and hyaluronan increased amyloid fibril content and resistance to proteolysis 2- to 5-fold, whereas in the presence of the cationic polysaccharide chitosan, A beta(42) fibrillar species were reduced by 25% and sensitivity to protease degradation increased similar to 3-fold. Fibrils of intermediate stability were obtained in the presence of PVS, an anionic polymer with more tightly packed charges than GAGs. Important structural differences between A beta(42) fibrils induced by PVS and A beta(42) fibrils obtained in the presence of GAGs and hyaluronan were observed by AFM, whereas mainly precursor protofibrillar forms were detected after incubation with chitosan. Computed binding energies per peptide from -11.2 to -13.5 kcal/mol were calculated for GAGs and PVS, whereas a significantly lower value of -7.4 kcal/mol was obtained for chitosan. Taken together, our data suggest a simple and straightforward mechanism to explain the role of GAGs as enhancers of the formation of insoluble A beta(42) fibrils trapping soluble toxic forms.

Keywords: Alzheimer's disease, Amyloid fibril structure, Fibrillogenesis enhancers and inhibitors, Polysaccharides


Valente, T., Gella, A., Fernàndez-Busquets, X., Unzeta, M., Durany, N., (2010). Immunohistochemical analysis of human brain suggests pathological synergism of Alzheimer's disease and diabetes mellitus Neurobiology of Disease , 37, (1), 67-76

It has been extensively reported that diabetes mellitus (DM) patients have a higher risk of developing Alzheimer's disease (AD). but a mechanistic connection between both pathologies has not been provided so far Carbohydrate-derived advanced glycation endproducts (AGEs) have been implicated in the chronic complications of DM and have been reported to play an important role in the pathogenesis of AD. The earliest histopathological manifestation of AD is the apparition of extracellular aggregates of the amyloid beta peptide (A beta). To investigate possible correlations between AGEs and A beta aggregates with both pathologies. we have performed an immuhistochemical study in human post-mortem samples of AD, AD with diabetes (ADD). diabetic and nondemented controls ADD brains showed increased number of A beta dense plaques and receptor for AGEs (RACE)-positive and Tau-positive cells, higher AGEs levels and major microglial activation, compared to AD brain. Our results indicate that ADD patients present a significant increase of cell damage through a RAGE-dependent mechanism, suggesting that AGEs may promote the generation of an oxidative stress vicious cycle, which can explain the severe progression of patients with both pathologies.

Keywords: Abeta, Alzheimer's disease, Rage, Ages, Diabetes, Immunohistochemistry, Advanced glycation endproducts, Beta-amyloid peptide, End-products, Oxidative stress, Advanced glycosylation, Synaptic dysfunction, Cross-linking


Gavín, R., Ferrer, Isidro, del Río, J. A., (2010). Involvement of Dab1 in APP processing and [beta]-amyloid deposition in sporadic Creutzfeldt-Jakob patients Neurobiology of Disease , 37, (2), 324-329

Alzheimer's disease and prion pathologies (e.g., Creutzfeldt-Jakob disease (CJD)) display profound neural lesions associated with aberrant protein processing and extracellular amyloid deposits. Dab1 has been implicated in the regulation of amyloid precursor protein (APP), but a direct link between human prion diseases and Dab1/APP interactions has not been published. Here we examined this putative relationship in 17 cases of sporadic CJD (sCJD) post-mortem. Biochemical analyses of brain tissue revealed two groups, which also correlated with PrPsc types 1 and 2. One group with PrPsc type 1 showed increased Dab1 phosphorylation and lower [beta]CTF production with an absence of A[beta] deposition. The second sCJD group, which carried PrPsc type 2, showed lower levels of Dab1 phosphorylation and [beta]CTF production, and A[beta] deposition. Thus, the present observations suggest a correlation between Dab1 phosphorylation, A[beta] deposition and PrPsc type in sCJD.

Keywords: Prionopathies, Amyloid plaques, Alzheimer's disease, Dab1


Fernàndez-Busquets, X., Ponce, J., Bravo, R., Arimon, M., Martianez, T., Gella, A., Cladera, J., Durany, N., (2010). Modulation of amyloid beta peptide(1-42) cytotoxicity and aggregation in vitro by glucose and chondroitin sulfate Current Alzheimer Research , 7, (5), 428-438

One mechanism leading to neurodegeneration during Alzheimer's Disease (AD) is amyloid beta peptide (A beta)-induced neurotoxicity. Among the factors proposed to potentiate A beta toxicity is its covalent modification through carbohydrate-derived advanced glycation endproducts (AGEs). Other experimental evidence, though, indicates that certain polymeric carbohydrates like the glycosaminoglycan (GAG) chains found in proteoglycan molecules attenuate the neurotoxic effect of A beta in primary neuronal cultures. Pretreatment of the 42-residue A beta fragment (A beta(1-42)) with the ubiquitous brain carbohydrates, glucose, fructose, and the GAG chondroitin sulfate B (CSB) inhibits A beta beta(1-42)-induced apoptosis and reduces the peptide neurotoxicity on neuroblastoma cells, a cytoprotective effect that is partially reverted by AGE inhibitors such as pyridoxamine and L-carnosine. Thioflavin T fluorescence measurements indicate that at concentrations close to physiological, only CSB promotes the formation of A beta amyloid fibril structure. Atomic force microscopy imaging and Western blot analysis suggest that glucose favours the formation of globular oligomeric structures derived from aggregated species. Our data suggest that at short times carbohydrates reduce A beta(1-42) toxicity through different mechanisms both dependent and independent of AGE formation.

Keywords: Alzheimer's disease, Advanced glycation endproducts, Amyloid fibrils, Amyloid beta peptide, Apoptosis, Carbohydrates, Glycosaminoglycans


Sabaté, R., Espargaró, A., de Groot, N. S., Valle-Delgado, J. J., Fernàndez-Busquets, X., Ventura, S., (2010). The role of protein sequence and amino acid composition in amyloid formation: Scrambling and backward reading of IAPP amyloid fibrils Journal of Molecular Biology , 404, (2), 337-352

The specific functional structure of natural proteins is determined by the way in which amino acids are sequentially connected in the polypeptide. The tight sequence/structure relationship governing protein folding does not seem to apply to amyloid fibril formation because many proteins without any sequence relationship have been shown to assemble into very similar β-sheet-enriched structures. Here, we have characterized the aggregation kinetics, seeding ability, morphology, conformation, stability, and toxicity of amyloid fibrils formed by a 20-residue domain of the islet amyloid polypeptide (IAPP), as well as of a backward and scrambled version of this peptide. The three IAPP peptides readily aggregate into ordered, β-sheet-enriched, amyloid-like fibrils. However, the mechanism of formation and the structural and functional properties of aggregates formed from these three peptides are different in such a way that they do not cross-seed each other despite sharing a common amino acid composition. The results confirm that, as for globular proteins, highly specific polypeptide sequential traits govern the assembly pathway, final fine structure, and cytotoxic properties of amyloid conformations.

Keywords: Amyloid formation, Islet amyloid polypeptide, Protein aggregation, Protein sequence, Retro proteins


Guix, F. X., Ill-Raga, G., Bravo, R., Nakaya, T., de Fabritiis, G., Coma, M., Miscione, G. P., Villa-Freixa, J., Suzuki, T., Fernàndez-Busquets, X., Valverde, M. A., de Strooper, B., Munoz, F. J., (2009). Amyloid-dependent triosephosphate isomerase nitrotyrosination induces glycation and tau fibrillation Brain , 132, (5), 1335-1345

Alzheimer's disease neuropathology is characterized by neuronal death, amyloid beta-peptide deposits and neurofibrillary tangles composed of paired helical filaments of tau protein. Although crucial for our understanding of the pathogenesis of Alzheimer's disease, the molecular mechanisms linking amyloid beta-peptide and paired helical filaments remain unknown. Here, we show that amyloid beta-peptide-induced nitro-oxidative damage promotes the nitrotyrosination of the glycolytic enzyme triosephosphate isomerase in human neuroblastoma cells. Consequently, nitro-triosephosphate isomerase was found to be present in brain slides from double transgenic mice overexpressing human amyloid precursor protein and presenilin 1, and in Alzheimer's disease patients. Higher levels of nitro-triosephosphate isomerase (P < 0.05) were detected, by Western blot, in immunoprecipitates from hippocampus (9 individuals) and frontal cortex (13 individuals) of Alzheimer's disease patients, compared with healthy subjects (4 and 9 individuals, respectively). Triosephosphate isomerase nitrotyrosination decreases the glycolytic flow. Moreover, during its isomerase activity, it triggers the production of the highly neurotoxic methylglyoxal (n = 4; P < 0.05). The bioinformatics simulation of the nitration of tyrosines 164 and 208, close to the catalytic centre, fits with a reduced isomerase activity. Human embryonic kidney (HEK) cells overexpressing double mutant triosephosphate isomerase (Tyr164 and 208 by Phe164 and 208) showed high methylglyoxal production. This finding correlates with the widespread glycation immunostaining in Alzheimer's disease cortex and hippocampus from double transgenic mice overexpressing amyloid precursor protein and presenilin 1. Furthermore, nitro-triosephosphate isomerase formed large beta-sheet aggregates in vitro and in vivo, as demonstrated by turbidometric analysis and electron microscopy. Transmission electron microscopy (TEM) and atomic force microscopy studies have demonstrated that nitro-triosephosphate isomerase binds tau monomers and induces tau aggregation to form paired helical filaments, the characteristic intracellular hallmark of Alzheimer's disease brains. Our results link oxidative stress, the main etiopathogenic mechanism in sporadic Alzheimer's disease, via the production of peroxynitrite and nitrotyrosination of triosephosphate isomerase, to amyloid beta-peptide-induced toxicity and tau pathology.

Keywords: Alzheimer's disease, Amyloid β-peptide, Tau protein, Triosephosphate isomerase, Peroxynitrite


Morell, M., Bravo, R., Espargaro, A., Sisquella, X., Aviles, F. X., Fernàndez-Busquets, X., Ventura, S., (2008). Inclusion bodies: Specificity in their aggregation process and amyloid-like structure Biochimica et Biophysica Acta - Molecular Cell Research , 1783, (10), 1815-1825

The accumulation of aggregated protein in the cell is associated with the pathology of many diseases and constitutes a major concern in protein production. Intracellular aggregates have been traditionally regarded as nonspecific associations of misfolded polypeptides. This view is challenged by studies demonstrating that, in vitro, aggregation often involves specific interactions. However, little is known about the specificity of in vivo protein deposition. Here, we investigate the degree of in vivo co-aggregation between two self-aggregating proteins, A beta A2 amyloid peptide and foot-and-mouth disease virus VP1 capsid protein, in prokaryotic cells. In addition, the ultrastructure of intracellular aggregates is explored to decipher whether amyloid fibrils and intracellular protein inclusions share structural properties. The data indicate that in vivo protein aggregation exhibits a remarkable specificity that depends on the establishment of selective interactions and results in the formation of oligomeric and fibrillar structures displaying amyloid-like properties. These features allow prokaryotic A beta A2 intracellular aggregates to act as effective seeds in the formation of A beta A2 amyloid fibrils. overall, our results suggest that conserved mechanisms underlie protein aggregation in different organisms. They also have important implications for biotechnological and biomedical applications of recombinant polypeptides.

Keywords: Protein aggregation, Inclusion bodies, Conformational diseases, Amyloid fibrils, Protein folding


Arimon, M., Grimminger, V., Sanz, F., Lashuel, H. A., (2008). Hsp104 targets multiple intermediates on the amyloid pathway and suppresses the seeding capacity of A beta fibrils and protofibrils Journal of Molecular Biology , 384, (5), 1157-1173

The heat shock protein Hsp104 has been reported to possess the ability to. modulate protein aggregation and toxicity and to "catalyze" the disaggregation and recovery of protein aggregates, including amyloid fibrils, in yeast, Escherichia coli, mammalian cell cultures, and animal models of Huntington's disease and Parkinson's disease. To provide mechanistic insight into the molecular mechanisms by which Hsp104 modulates aggregation and fibrillogenesis, the effect of Hsp104 on the fibrillogenesis of amyloid beta (A(3) was investigated by characterizing its ability to interfere with oligomerization and fibrillogenesis of different species along the amyloid-formation pathway of A beta. To probe the disaggregation activity of Hsp104, its ability to dissociate preformed protofibrillar and fibrillar aggregates of A beta was assessed in the presence and in the absence of ATP. Our results show that Hsp104 inhibits the fibrillization of monomeric and protofibrillar forms of A beta in a concentration-dependent but ATP-independent manner. Inhibition of A beta fibrillization by Hsp104 is observable up to Hsp104/A beta stoichiometric ratios of 1:1000, suggesting a preferential interaction of Hsp104 with aggregation intermediates (e.g., oligomers, protofibrils, small fibrils) on the pathway of A beta amyloid formation. This hypothesis is consistent with our observations that Hsp104 (i) interacts with A beta protofibrils, (ii) inhibits conversion of protofibrils into amyloid fibrils, (iii) arrests fibril elongation and reassembly, and (iv) abolishes the capacity of protofibrils and sonicated fibrils to seed the fibrillization of monomeric A beta. Together, these findings suggest that the strong inhibition of A beta fibrillization by Hsp104 is mediated by its ability to act at different stages and target multiple intermediates on the pathway to amyloid formation.

Keywords: Amyloid formation A beta, Hsp104, Disaggregation, Alzheimer's diseases