RESUMEN
Calcium ion regulation plays a crucial role in maintaining neuronal functions such as neurotransmitter release and synaptic plasticity. Copper (Cu2+ ) coordination to amyloid-ß (Aß) has accelerated Aß1-42 aggregation that can trigger calcium dysregulation by enhancing the influx of calcium ions by extensive perturbing integrity of the membranes. Aß1-42 aggregation, calcium dysregulation, and membrane damage are Alzheimer disease (AD) implications. To gain a detail of calcium ions' role in the full-length Aß1-42 and Aß1-42 -Cu2+ monomers contact, the cellular membrane before their aggregation to elucidate the neurotoxicity mechanism, we carried out 2.5 µs extensive molecular dynamics simulation (MD) to rigorous explorations of the intriguing feature of the Aß1-42 and Aß1-42 -Cu2+ interaction with the dimyristoylphosphatidylcholine (DMPC) bilayer in the presence of calcium ions. The outcome of the results compared to the same simulations without calcium ions. We surprisingly noted robust binding energies between the Aß1-42 and membrane observed in simulations containing without calcium ions and is two and a half fold lesser in the simulation with calcium ions. Therefore, in the case of the absence of calcium ions, N-terminal residues of Aß1-42 deeply penetrate from the surface to the center of the bilayer; in contrast to calcium ions presence, the N- and C-terminal residues are involved only in surface contacts through binding phosphate moieties. On the other hand, Aß1-42 -Cu2+ actively participated in surface bilayer contacts in the absence of calcium ions. These contacts are prevented by forming a calcium bridge between Aß1-42 -Cu2+ and the DMPC bilayer in the case of calcium ions presence. In a nutshell, Calcium ions do not allow Aß1-42 penetration into the membranes nor contact of Aß1-42 -Cu2+ with the membranes. These pieces of information imply that the calcium ions mediate the membrane perturbation via the monomer interactions but do not damage the membrane; they agree with the western blot experimental results of a higher concentration of calcium ions inhibit the membrane pore formation by Aß peptides.
Asunto(s)
Enfermedad de Alzheimer , Humanos , Enfermedad de Alzheimer/metabolismo , Calcio , Dimiristoilfosfatidilcolina , Fragmentos de Péptidos/química , Péptidos beta-Amiloides/química , Cobre/química , IonesRESUMEN
α-Synuclein (αSyn) species can be detected in synaptic boutons, where they play a crucial role in the pathogenesis of Parkinson's Disease (PD). However, the effects of intracellular αSyn species on synaptic transmission have not been thoroughly studied. Here, using patch-clamp recordings in hippocampal neurons, we report that αSyn oligomers (αSynO), intracellularly delivered through the patch electrode, produced a fast and potent effect on synaptic transmission, causing a substantial increase in the frequency, amplitude and transferred charge of spontaneous synaptic currents. We also found an increase in the frequency of miniature synaptic currents, suggesting an effect located at the presynaptic site of the synapsis. Furthermore, our in silico approximation using docking analysis and molecular dynamics simulations showed an interaction between a previously described small anti-amyloid beta (Aß) molecule, termed M30 (2-octahydroisoquinolin-2(1H)-ylethanamine), with a central hydrophobic region of αSyn. In line with this finding, our empirical data aimed to obtain oligomerization states with thioflavin T (ThT) and Western blot (WB) indicated that M30 interfered with αSyn aggregation and decreased the formation of higher-molecular-weight species. Furthermore, the effect of αSynO on synaptic physiology was also antagonized by M30, resulting in a decrease in the frequency, amplitude, and charge transferred of synaptic currents. Overall, the present results show an excitatory effect of intracellular αSyn low molecular-weight species, not previously described, that are able to affect synaptic transmission, and the potential of a small neuroactive molecule to interfere with the aggregation process and the synaptic effect of αSyn, suggesting that M30 could be a potential therapeutic strategy for synucleinopathies.
Asunto(s)
Isoquinolinas/farmacología , Neuronas/citología , alfa-Sinucleína/química , alfa-Sinucleína/metabolismo , Animales , Benzotiazoles/farmacología , Células Cultivadas , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Ratones , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Unión Proteica , Dominios Proteicos , Ratas , Transmisión SinápticaRESUMEN
Amyloid beta (Aß) oligomers are the most neurotoxic aggregates causing neuronal death and cognitive damage. A detailed elucidation of the aggregation pathways from oligomers to fibril formation is crucial to develop therapeutic strategies for Alzheimer's disease (AD). Although experimental techniques rely on the measure of time- and space-average properties, they face severe difficulties in the investigation of Aß peptide aggregation due to their intrinsically disorder character. Computer simulation is a tool that allows tracing the molecular motion of molecules; hence it complements Aß experiments, as it allows to explore the binding mechanism between metal ions and Aß oligomers close to the cellular membrane at the atomic resolution. In this context, integrated studies of experiments and computer simulations can assist in mapping the complete pathways of aggregation and toxicity of Aß peptides. Aß oligomers are disordered proteins, and due to a rapid exploration of their intrinsic conformational space in real-time, they are challenging therapeutic targets. Therefore, no good drug candidate could have been identified for clinical use. Our previous investigations identified two small molecules, M30 (2-Octahydroisoquinolin-2(1H)-ylethanamine) and Gabapentin, capable of Aß binding and inhibiting molecular aggregation, synaptotoxicity, intracellular calcium signaling, cellular toxicity and memory losses induced by Aß. Thus, we recommend these molecules as novel candidates to assist anti-AD drug discovery in the near future. This review discusses the most recent research investigations about the Aß dynamics in water, close contact with cell membranes, and several therapeutic strategies to remove plaque formation.
Asunto(s)
Enfermedad de Alzheimer/prevención & control , Péptidos beta-Amiloides/metabolismo , Ansiolíticos/uso terapéutico , Gabapentina/uso terapéutico , Hidroxiquinolinas/uso terapéutico , Bibliotecas de Moléculas Pequeñas/uso terapéutico , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Animales , HumanosRESUMEN
In the past two decades, the world has faced several infectious disease outbreaks. Ebola, Influenza A (H1N1), SARS, MERS, and Zika virus have had a massive global impact in terms of economic disruption, the strain on local and global public health. Most recently, the global outbreak of novel coronavirus 2019 (SARS-CoV-2) that causes COVID-19 is a newly discovered virus from the coronavirus family in Wuhan city, China, known to be a great threat to the public health systems. As of 15 April 2020, The Johns Hopkins University estimated that the COVID-19 affected more than two million people, resulting in a death toll above 130,000 around the world. Infected people in Europe and America correspond about 40% and 30% of the total reported cases respectively. At this moment only few Asian countries have controlled the disease, but a second wave of new infections is expected. Predicting inhibitor and target to the COVID-19 is an urgent need to protect human from the disease. Therefore, a protocol to identify anti-COVID-19 candidate based on computer-aided drug design is urgently needed. Thousands of compounds including approved drugs and drugs in the clinical trial are available in the literature. In practice, experimental techniques can measure the time and space average properties but they cannot be captured the structural variation of the COVID-19 during the interaction of inhibitor. Computer simulation is particularly suitable to complement experiments to elucidate conformational changes at the molecular level which are related to inhibition process of the COVID-19. Therefore, computational simulation is essential tool to elucidate the phenomenon. The structure-based virtual screening computational approach will be used to filter the best drugs from the literature, the investigate the structural variation of COVID-19 with the interaction of the best inhibitor is a fundamental step to design new drugs and vaccines which can combat the coronavirus. This mini-review will address novel coronavirus structure, mechanism of action, and trial test of antiviral drugs in the lab and patients with COVID-19.
Asunto(s)
COVID-19 , Subtipo H1N1 del Virus de la Influenza A , Infección por el Virus Zika , Virus Zika , Antivirales/farmacología , Simulación por Computador , Humanos , SARS-CoV-2RESUMEN
Oligomeric ß-amyloid peptide (Aß) is one of the main neurotoxic agents of Alzheimer's disease (AD). Oligomers associate to neuronal membranes, forming "pore-like" structures that cause intracellular calcium and neurotransmitter dyshomeostasis, leading to synaptic failure and death. Through molecular screening targeting the C terminal region of Aß, a region involved in the toxic properties of the peptide, we detected an FDA approved compound, gabapentin (GBP), with neuroprotective effects against Aß toxicity. At micromolar concentrations, GBP antagonized peptide aggregation over time and reduced the Aß absorbance plateau to 28% of control. In addition, GBP decreased Aß association to membranes by almost half, and the effects of Aß on intracellular calcium in hippocampal neurons were antagonized without causing effects on its own. Finally, we found that GBP was able to block the synaptotoxicity induced by Aß in hippocampal neurons, increasing post-synaptic currents from 1.7 ± 0.9 to 4.2 ± 0.7 fC and mean relative fluorescence intensity values of SV2, a synaptic protein, from 0.7 ± 0.09 to 1.00 ± 0.08. The results show that GBP can interfere with Aß-induced toxicity by blocking multiple steps, resulting in neuroprotection, which justifies advancing toward additional animal and human studies.
Asunto(s)
Enfermedad de Alzheimer , Péptidos beta-Amiloides , Enfermedad de Alzheimer/tratamiento farmacológico , Péptidos beta-Amiloides/metabolismo , Péptidos beta-Amiloides/toxicidad , Animales , Gabapentina/farmacología , Hipocampo/metabolismo , Humanos , Neuronas/metabolismo , Fragmentos de PéptidosRESUMEN
The aggregation of Aß42 peptides is considered as one of the main causes for the development of Alzheimer's disease. In this context, Zn2+ and Cu2+ play a significant role in regulating the aggregation mechanism, due to changes in the structural and the solvation free energy of Aß42. In practice, experimental studies are not able to determine the latter properties, since the Aß42-Zn2+ and Aß42-Cu2+ peptide complexes are intrinsically disordered, exhibiting rapid conformational changes in the aqueous environment. Here, we investigate atomic structural variations and the solvation thermodynamics of Aß42, Aß42-Cu2+ , and Aß42-Zn2+ systems in explicit solvent (water) by using quantum chemical structures as templates for a metal binding site and combining extensive all-atom molecular dynamics (MD) simulations with a thorough solvation thermodynamic analysis. Our results show that the zinc and copper coordination results in a significant decrease of the solvation free energy in the C-terminal region (Met35-Val40), which in turn leads to a higher structural disorder. In contrast, the ß-sheet formation at the same C-terminal region indicates a higher solvation free energy in the case of Aß42. The solvation free energy of Aß42 increases upon Zn2+ binding, due to the higher tendency of forming the ß-sheet structure at the Leu17-Ala42 residues, in contrast to the case of binding with Cu2+ . Finally, we find the hydrophobicity of Aß42-Zn2+ in water is greater than in the case of Aß42-Cu2+ .
Asunto(s)
Péptidos beta-Amiloides/química , Cobre/química , Fragmentos de Péptidos/química , Agua/química , Zinc/química , Péptidos beta-Amiloides/metabolismo , Sitios de Unión , Cationes Bivalentes , Cobre/metabolismo , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Cinética , Simulación de Dinámica Molecular , Fragmentos de Péptidos/metabolismo , Unión Proteica , Conformación Proteica en Hélice alfa , Conformación Proteica en Lámina beta , Dominios y Motivos de Interacción de Proteínas , Soluciones , Termodinámica , Agua/metabolismo , Zinc/metabolismoRESUMEN
INTRODUCTION: Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder in elderly people. Existent therapies are directed at alleviating some symptoms, but are not effective in altering the course of the disease. METHODS: Based on our previous study that showed that an Aß-interacting small peptide protected against the toxic effects of amyloid-beta peptide (Aß), we carried out an array of in silico, in vitro, and in vivo assays to identify a molecule having neuroprotective properties. RESULTS: In silico studies showed that the molecule, referred to as M30 (2-Octahydroisoquinolin-2(1H)-ylethanamine), was able to interact with the Aß peptide. Additionally, in vitro assays showed that M30 blocked Aß aggregation, association to the plasma membrane, synaptotoxicity, intracellular calcium, and cellular toxicity, while in vivo experiments demonstrated that M30 induced a neuroprotective effect by decreasing the toxicity of Aß in the dentate gyrus of the hippocampus and improving the alteration in spatial memory in behavior assays. DISCUSSION: Therefore, we propose that this new small molecule could be a useful candidate for the additional development of a treatment against AD since it appears to block multiple steps in the amyloid cascade. Overall, since there are no drugs that effectively block the progression of AD, this approach represents an innovative strategy. SIGNIFICANCE: Currently, there is no effective treatment for AD and the expectations to develop an effective therapy are low. Using in silico, in vitro, and in vivo experiments, we identified a new compound that is able to inhibit Aß-induced neurotoxicity, specifically aggregation, association to neurons, synaptic toxicity, calcium dyshomeostasis and memory impairment induced by Aß. Because Aß toxicity is central to AD progression, the inhibition mediated by this new molecule might be useful as a therapeutic tool.