ACS Chemical Neuroscience最新文献

The unique architecture of the brain and the blood-brain barrier imposes challenges for the measurement of parenchyma-derived biomarkers that prevent sufficient understanding of transient neuropathogenic processes. One solution to this challenge is direct sampling of brain interstitial fluid via implanted microperfusion probes. Seeking to understand spatial limitations to microperfusion in the brain, we employed computational fluid dynamics modeling and empirical recovery of fluorescently labeled dextrans in an animal model. We found that dextrans were successfully recovered via microperfusion over a 6 h sampling period, especially at probes implanted 2 mm from the dextran infusion point relative to probes implanted 5 mm from the injection site. Experimental recovery was consistently around 1% of simulated, suggesting that this parameter can be used to set practical limits on the maximal tissue concentration of proteins measured in microperfusates and on the spatial domain sampled by our multimodal microperfusion probe.

Early-stage aggregates of amyloid-forming proteins, specifically soluble oligomers, are implicated in neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. Protein aggregation is typically monitored by fluorescence using the amyloid-binding fluorophore thioflavin T (ThT). Thioflavin T interacts, however, preferentially with fibrillar amyloid structures rather than with soluble, early-stage aggregates. In contrast, the two fluorophores, aminonaphthalene 2-cyanoacrylate-spiropyran (AN-SP) and triazole-containing boron-dipyrromethene (taBODIPY), were reported to bind preferentially to early-stage aggregates of amyloidogenic proteins. The present study compares ThT with AN-SP and taBODIPY with regard to their ability to monitor early stages of aggregation of four different amyloid-forming proteins, including amyloid-β (Aβ), tau protein, amylin, and α-synuclein. The results show that the three fluorophores vary in their suitability to monitor the early aggregation of different amyloid-forming proteins. For instance, in the presence of Aβ and amylin, the fluorescence intensity of AN-SP increased at an earlier stage of aggregation than the fluorescence of ThT, albeit with only a small fluorescence increase in the case of AN-SP. In contrast, in the presence of tau and amylin, the fluorescence intensity of taBODIPY increased at an earlier stage of aggregation than the fluorescence of ThT. Finally, α-synuclein aggregation could only be monitored by ThT fluorescence; neither AN-SP nor taBODIPY showed a significant increase in fluorescence over the course of aggregation of α-synuclein. These results demonstrate the ability of AN-SP and taBODIPY to monitor the formation of early-stage aggregates from specific amyloid-forming proteins at an early stage of aggregation, although moderate increases in fluorescence intensity, relatively large uncertainties in fluorescence values, and limited solubility of both fluorophores limit their usefulness for some amyloid proteins. The capability to monitor early aggregation of some amyloid proteins, such as amylin, might accelerate the discovery of aggregation inhibitors to minimize the formation of toxic oligomeric species for potential therapeutic use.

Preclinical and clinical studies have indicated that compromised blood–brain barrier (BBB) function contributes to Alzheimer’s disease (AD) pathology. BBB breakdown ranged from mild disruption of tight junctions (TJs) with increased BBB permeability to chronic integrity loss, affecting transport across the BBB, reducing brain perfusion, and triggering inflammatory responses. We recently developed a high-throughput screening (HTS) assay to identify hit compounds that enhance the function of a cell-based BBB model. The HTS screen identified (S,E)-2-acetyl-6-[3-(4′-fluorobiphenyl-4-yl)acryloyl]-3,7,9-trihydroxy-8,9b-dimethyldibenzo-[b,d]furan-1(9bH)-one (4-FPBUA), a semisynthetic analogue of naturally occurring usnic acid, which protected the in vitro model against Aβ toxicity. Usnic acid is a lichen-derived secondary metabolite with a unique dibenzofuran skeleton that is commonly found in lichenized fungi of the genera Usnea. In this study, we aimed to evaluate the effect of 4-FPBUA in vitro on the cell-based BBB model function and its in vivo ability to rectify BBB function and reduce brain Aβ in two AD mouse models, namely, 5xFAD and TgSwDI. Our findings demonstrated that 4-FPBUA enhanced cell-based BBB function, increased Aβ transport across the monolayer, and reversed BBB breakdown in vivo by enhancing autophagy as an mTOR inhibitor. Induced autophagy was associated with a significant reduction in Aβ accumulation and related pathologies and improved memory function. These results underscore the potential of 4-FPBUA as a candidate for further preclinical exploration to better understand its mechanisms of action and to optimize dosing strategies. Continued research may also elucidate additional pathways through which 4-FPBUA contributed to the amelioration of BBB dysfunction in AD. Collectively, our findings supported the development of 4-FPBUA as a therapeutic agent against AD.

Various oligomeric species of amyloid-beta have been proposed to play different immunogenic roles in the cellular pathology of Alzheimer’s Disease. The dynamic interconversion between various amyloid oligomers and fibrillar assemblies makes it difficult to elucidate the role each potential aggregation state may play in driving neuroinflammatory and neurodegenerative pathology. The ability to identify the amyloid species that are key and essential drivers of these pathological hallmarks of Alzheimer’s Disease is of fundamental importance for also understanding downstream events including tauopathies that mediate neuroinflammation with neurologic deficits. Here, we report the design and construction of a quantum dot mimetic for larger spherical oligomeric amyloid species as an “endogenously” fluorescent proxy for this cytotoxic assembly of amyloid to investigate its role in inducing inflammatory and stress response states in neuronal and glial cell types. The design parameters and construction protocol developed here may be adapted for developing quantum dot nano-bio assemblies for other biological systems of interest, particularly neurodegenerative diseases involving other protein aggregates.

Ischemic stroke is a serious condition that results in high rates of illness and death. Anaerobic glycolysis becomes the primary means of providing energy to the brain during periods of low oxygen levels, such as in the aftermath of an ischemic stroke. This process is essential for maintaining vital brain functions and has significant implications for recovery following a stroke. Energy supply by anaerobic glycolysis and acidosis caused by lactic acid accumulation are important pathological processes after ischemic stroke. Numerous natural products regulate glucose and lactate, which in turn modulate anaerobic glycolysis. This article focuses on the relationship between anaerobic glycolysis and ischemic stroke, as well as the associated signaling pathways and natural products that play a therapeutic role. These natural products, which can regulate anaerobic glycolysis, will provide new avenues and perspectives for the treatment of ischemic stroke in the future.

Alzheimer’s disease (AD) stands as one of the most prevalent neurodegenerative conditions, leading to cognitive impairment, with no cure and preventive measures. Misfolding and aberrant aggregation of amyloid-β (Aβ) peptides are believed to be the underlying cause of AD. These amyloid aggregates culminate in the development of toxic Aβ oligomers and subsequent accumulation of β-amyloid plaques amidst neuronal cells in the brain, marking the hallmarks of AD. Drug development for the potentially curative treatment of Alzheimer’s is, therefore, a tremendous challenge for the scientific community. In this study, we investigate the potency of Whitlock’s caffeine-armed molecular tweezer in combating the deleterious effects of Aβ aggregation, with special emphasis on the seven residue Aβ_16–22 fragment. Extensive all-atom molecular dynamics simulations are conducted to probe the various structural and conformational transitions of the peptides in an aqueous medium in both the presence and absence of tweezers. To explore the specifics of peptide–tweezer interactions, radial distribution functions, contact number calculations, binding free energies, and 2-D kernel density plots depicting the variation of distance-angle between the aromatic planes of the peptide–tweezer pair are computed. The central hydrophobic core, particularly the aromatic Phe residues, is crucial in the development of harmful amyloid oligomers. Notably, all analyses indicate reduced interpeptide interactions in the presence of the tweezer, which is attributed to the tweezer-Phe aromatic interaction. Upon increasing the tweezer concentration, the residues of the peptide are further encased in a hydrophobic environment created by the self-aggregating tweezer cluster, leading to the segregation of the peptide residues. This is further aided by the weakening of interstrand hydrogen bonding between the peptides, thereby impeding their self-aggregation and preventing the formation of neurotoxic β-amyloid. Furthermore, the study also highlights the efficacy of the molecular tweezer in destabilizing preformed amyloid fibrils as well as hindering the aggregation of the full-length Aβ_1–42 peptide.

Obsessive-compulsive disorder (OCD) is a debilitating mental disorder with obvious difficulties in treatment. Its pathogenesis has not been fully elucidated. Further understanding of etiology and mechanism needs to be explored further. We employed the isobaric tag for relative and absolute quantitation (iTRAQ)-based proteomic analysis to compare serum proteome profile between OCD patients and healthy controls, in order to find out the possible mechanism of OCD in the downstream biological process. Eighty-one drug-free OCD patients and 78 healthy controls were enrolled. A total of 475 proteins were identified. Totally, 80 proteins with p < 0.05 were selected for gene set enrichment analysis (GSEA), and only those with a fold change ≥1.2 and q value <0.2 between groups were accepted as differentially expressed proteins (DEPs). We observed a significant enrichment of immuno-inflammation-related pathways, along with intriguing expression trends that immuno-inflammation-related proteins were upregulated in GSEA. After that, 2 up-regulated proteins and 13 down-regulated ones were accepted as DEP. According to the available literature, most of the DEPs have not been reported in OCD. These DEPs were enriched in 121 gene ontology (GO) terms, including hepatocyte growth factor receptor activity, angiogenin-PRI complex, and so on. DEPs were enriched in pathways including adherens junction in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Alterations in DEPs including STXBP5L, GRN, and ANG were validated in OCD animal models. Our study suggested that OCD patients manifested multifactorial impairment in neuronal or non-neuronal cellular function under the inflammatory background. Further research employing larger sample sizes, longitudinal design, stratified analysis, and multiomics methodology will be needed. Experiments in laboratories were essential in illuminating the mechanism.

Polycystic ovary syndrome (PCOS) is an intricate endocrine disorder that targets millions of women globally. Recent research has drawn attention to its association with cognitive impairment and Alzheimer’s disease (AD) risk, yet the exact mechanism remains elusive. This study aimed to explore the potential role of PCOS-associated insulin resistance (IR) and inflammation in linking PCOS to AD pathogenesis. It additionally investigated the therapeutic merits of pterostilbene (PTS) in ameliorating PCOS and associated cognitive deficits in comparison to metformin (MET). Rats were divided into five groups; vehicle group, PTS group [30 mg/kg, per os (p.o.) for 13 days], and the remaining three groups received letrozole (1 mg/kg, p.o. for 21 days) to represent the PCOS, PCOS + MET (300 mg/kg, p.o. for 13 days), and PCOS + PTS groups, respectively. Behavioral tests were conducted, along with a histopathological investigation of brains and ovaries. Assessment of serum hormonal profile and hippocampal IRS-1/PI3K/AKT/GSK-3β insulin signaling pathway components were performed. PTS rats exhibited improved insulin sensitivity and hormonal profile, besides enhanced neurobehavioral tests performance and histopathological findings. These effects may be attributed to modulation of the IRS-1/PI3K/AKT/GSK-3β pathway, reducing GSK-3β activity, and mitigating Tau hyperphosphorylation and Aβ accumulation in the brain. Likewise, PTS attenuated nuclear factor kappa B-mediated inflammation and reversed AChE elevation, suggesting multifaceted neuroprotective effects. Comparatively, PTS showed outcomes similar to those of MET in most parameters. The obtained findings validated that dysregulated insulin signaling in PCOS rats detrimentally affects cognitive function, which is halted by PTS, unveiling the potential of PTS as a novel therapy for PCOS and related cognitive deficits.

Protein kinase CK2 is a holoenzyme composed of two regulatory subunits (CK2β) and two catalytic subunits (CK2α and CK2α'). CK2 controls several cellular processes, including proliferation, inflammation, and cell death. However, CK2α and CK2α' possess different expression patterns and substrates and therefore impact each of these processes differently. Elevated CK2α participates in the development of cancer, while increased CK2α' has been associated with neurodegeneration, especially Huntington's disease (HD). HD is a fatal disease for which no effective therapies are available. Genetic deletion of CK2α' in HD mouse models has ameliorated neurodegeneration. Therefore, pharmacological inhibition of CK2α' presents a promising therapeutic strategy for treating HD. However, current CK2 inhibitors are unable to discriminate between CK2α and CK2α' due to their high structural homology, especially in the targeted ATP-binding site. Using computational analyses, we found a potential type IV ("D" pocket) allosteric site that contained different residues between CK2α and CK2α' and was distal from the ATP-binding pocket featured in both kinases. We decided to look for allosteric modulators that might interact in a biased fashion with the type IV pocket on both CK2α and CK2α'. We screened a commercial library containing ∼29,000 allosteric-kinase-inhibitor-like compounds using a CK2α' activity-dependent ADP-Glo Kinase assay. Obtained hits were counter-screened against CK2α using the ADP-Glo Kinase assay, revealing two CK2α'-biased compounds. These two compounds might serve as the basis for further medicinal chemistry optimization for the potential treatment of HD.