scholarly journals OGA Inhibition Alters Energetics and Nutrient Sensing in Alzheimer’s Disease Cytoplasmic Hybrids

2020 ◽  
Vol 78 (4) ◽  
pp. 1743-1753
Author(s):  
Jarrod Flax ◽  
Heather M. Wilkins ◽  
Reegan Miller ◽  
Sarah Griffith ◽  
Gentry K. Cork ◽  
...  

Background: Alzheimer’s disease (AD) features reductions in key bioenergetic fluxes and perturbed mitochondrial function. Cytoplasmic hybrids (cybrids) generated through the transfer of AD subject mitochondria to mtDNA-depleted SH-SY5Y neuroblastoma cells recapitulate some of these features in an in vitro setting. Objective: For this study, we used the AD cybrid model to assess the impact of a nutrient-excess like-state via increasing O-GlcNAcylation on whole cell and mitochondrial homeostasis. Methods: We induced increased O-GlcNAc by treating AD and control cybrid cell lines with Thiamet G (TMG), an inhibitor of the O-GlcNAcase enzyme that mediates removal of the nutrient-dependent O-GlcNAc modification. Results: Relative to control cybrid cell lines, AD cybrid lines showed a blunted response to TMG-induced O-GlcNAcylation. At baseline, AD cybrid cell line mitochondria showed partial activation of several proteins that help maintain bioenergetic homeostasis such as AMP-Regulated Kinase suggesting that AD mitochondria initiate a state of nutrient stress promoting energetic compensation; however, this compensation reduces the capacity of cells to respond to additional nutrient-related stresses such as TMG treatment. Also, TMG caused disruptions in acetylation and Sirtuin 3 expression, while lowing total energetic output of the cell. Conclusion: Together, these findings suggest that modulation of O-GlcNAc is essential for proper energetic function of the mitochondria, and AD mitochondrial capacity to handle nutrient-excess is limited.

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 985 ◽  
Author(s):  
Sílvia Chaves ◽  
Simonetta Resta ◽  
Federica Rinaldo ◽  
Marina Costa ◽  
Romane Josselin ◽  
...  

A series of multi-target-directed ligands (MTDLs), obtained by attachment of a hydroxyphenylbenzimidazole (BIM) unit to donepezil (DNP) active mimetic moiety (benzyl-piperidine/-piperazine) was designed, synthesized, and evaluated as potential anti-Alzheimer’s disease (AD) drugs in terms of biological activity (inhibition of acetylcholinesterase (AChE) and β–amyloid (Aβ) aggregation), metal chelation, and neuroprotection capacity. Among the DNP-BIM hybrids studied herein, the structural isomerization did not significantly improve the biological properties, while some substitutions, namely fluorine atom in each moiety or the methoxy group in the benzyl ring, evidenced higher cholinergic AChE activity. All the compounds are able to chelate Cu and Zn metal ions through their bidentate BIM moieties, but compound 5, containing a three-dentate chelating unit, is the strongest Cu(II) chelator. Concerning the viability on neuroblastoma cells, compounds 9 and 10 displayed the highest reduction of Aβ-induced cell toxicity. In silico calculations of some pharmacokinetic descriptors indicate that all the compounds but the nitro derivatives have good potential oral-bioavailability. Overall, it can be concluded that most of the studied DNP-BIM conjugates showed quite good anti-AD properties, therefore deserving to be considered in further studies with the aim of understanding and treating AD.


2011 ◽  
Vol 23 (1) ◽  
pp. 245
Author(s):  
V. J. Hall ◽  
J. Jakobsen ◽  
A. Gunnarsson ◽  
M. Schmidt ◽  
A. Lund Jørgensen ◽  
...  

Alzheimer’s disease is the most prevalent cause of dementia and afflicts ∼26 million people worldwide. There are currently no cures for this disease. Production of in vitro models of the disease would be extremely useful for studying disease mechanisms and for potential screening of novel drugs. In this study we produced 2 hemizygote and 2 homozygote embryonic stem cell-derived neural progenitor cell lines from Day 8 transgenic blastocysts carrying a human gene linked to early-onset Alzheimer’s disease [Swedish mutation of the amyloid precursor protein (hAPPsw)]. Following onset of spontaneous oestrus, a mating of hAPPsw± × hAPPsw± Göttingen transgenic progeny was performed. Eight days after the first of 2 matings, embryos were flushed from the tip of both cornuas of the gilt under surgical anaesthesia. A total of 6 blastocysts were obtained and 7 corpora lutei recorded. Blastocysts were transported for 4 h in porcine zygote medium 3 (PZM-3) in hypoxic, humidified conditions at 39°C to the cell laboratory. Compact epiblasts were mechanically isolated from the embryo using insulin needles and cultured on inactivated mouse embryonic fibroblasts in embryonic stem cell medium, supplemented with 20 ng mL–1 human recombinant basic fibroblast growth factor (Prospec) and 20 ng mL–1 human recombinant Activin A (Prospec), for a period of 5 days in hypoxic conditions at 39°C. Five of the 6 epiblasts expanded to form embryonic stem-cell-like outgrowth colonies. These were cut into small colonies and plated on MS5 murine stromal cells to induce spontaneous neural differentiation in DMEM medium containing 15% knockout serum replacement. Neuronal rosette-like structures were identified from Day 10 of differentiation onward. Six rosette structures were mechanically isolated from 4 outgrowths and plated in serum-free conditions on Matrigel-coated dishes. Two of the 6 lines failed to proliferate beyond passage 2. The 4 remaining cell lines have currently been cultured to passage 7. These lines were analysed at passage 5 by comparative real-time PCR and found to be positive for the neural progenitor markers VIMENTIN, SOX2, NESTIN PAX6, MUSASHI; other neural markers BETAIIITUBULIN and NCAM; and the astrocyte marker, GFAP. These lines were also subjected to analysis by immunocytochemistry and found to express SOX2, VIMENTIN, and NESTIN. Further genotyping by comparative real-time PCR using primers designed to target the hAPPsw gene revealed that 2 lines carried a single copy of hAPPsw and 2 lines carried 2 copies of hAPPsw. The expression levels of the hAPPsw transgene in these cell lines were determined using quantitative PCR. These cell lines are currently being investigated for their ability to differentiate into cholinergic neurons and for their expression of hyperphosphorylated TAU and β-Amyloid secretion. These cell lines will be potentially relevant for the in vitro study of amyloid precursor protein accumulation in neural cells and its role in cell death, as well as for potential screening of novel drugs for Alzheimer’s disease.


CNS Spectrums ◽  
2010 ◽  
Vol 15 (S1) ◽  
pp. 7-7 ◽  
Author(s):  
Jeffrey L Cummings

Drs. McCaddon and Hudson provide a thorough review of the multiple ways in which vitamin B12, vitamin B6, folate, and homocysteine (Hey) are implicated in the pathogenesis of Alzheimer's disease (AD). They noted that Hey is more often elevated in AD and in mild cognitive impairment (MCI) than in cognitively healthy elderly; phosphatases needed to limit tau hyperphosphoryalation and neurofibrillary tangle formation require methylation and are dependent on folate and methylation status; cerebrospinal fluid (CSF) tau levels correlated with markers of methylation status; reduced folate and B12 levels lead to increase β-secretase and pesenilin 1 (PS1) actions leading to greater amyloid-β production in in vitro models; elevated Hey levels in rates are associated with increased PS1 activity and spatial memory deficits that are reversed following treatment with B12 and folate; raised Hey levels in vitro increase amyloid-β protein neurotoxicity; methylation impacts transmitters and transmitter function relevant to AD; in cultured neurons, Hey induces injury in DNA and stimulates cell death pathways. B12 deficiency leads to accumulation of methyl malonic acid, which inhibits mitochondrial function and may compromise energy generation and impair maintenance of synaptic plasticity. Methylation abnormalities result in excessive generation of reactive oxygen species that contribute importantly to cell injury. Biomarkers of oxidative injury, such as isoprostanes, are elevated in AD and suggest excess oxidation. Thus, there are multiple pathways through which deficient methylation may contribute to AD. In some cases, the observations are derived from models with B12 or folate deficiency and some in vitro observations have not been tested in in vivo models. There are no biomarkers specific to some of the pathways implicated and the magnitude of the impact of the deficiency or its treatment has not been established for all the relationships. Two open-label experiments in early- and late-stage AD patients have suggested benefit.


2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Panchanan Maiti ◽  
Gary L. Dunbar

Aggregation of amyloid beta protein (Aβ) and phosphorylated tau (p-Tau) plays critical roles in pathogenesis of Alzheimer’s disease (AD). As an antiamyloid natural polyphenol, curcumin (Cur) has a potential role in prevention of neurodegeneration in AD. However, due to limited absorption of the dietary Cur, the solid lipid Cur particles (SLCP) have been suggested as being more effective for AD therapy. In the present study, we compared the role of dietary Cur and SLCP on oxidative stress, neuronal death, p-Tau level, and certain cell survival markers in vitro, after exposure to Aβ42. Mouse neuroblastoma cells were exposed to Aβ42 for 24 h and incubated with or without dietary Cur and/or SLCP. Reactive oxygen species (ROS), apoptotic cell death, p-Tau, and tau kinase (including GSK-3β and cell survival markers, such as total Akt, phosphorylated Akt, and PSD95 levels) were investigated. SLCP showed greater permeability than dietary Cur in vitro, decreased ROS production, and prevented apoptotic death. In addition, SLCP also inhibited p-Tau formation and significantly decreased GSK-3β levels. Further, the cell survival markers, such as total Akt, p-Akt, and PSD95 levels, were more effectively maintained by SLCP than dietary Cur in Aβ42 exposed cells. Therefore, SLCP may provide greater neuroprotection than dietary Cur in Alzheimer’s disease.


2000 ◽  
Vol 162 (1) ◽  
pp. 37-50 ◽  
Author(s):  
Patricia A. Trimmer ◽  
Russell H. Swerdlow ◽  
Janice K. Parks ◽  
Paula Keeney ◽  
James P. Bennett ◽  
...  

2016 ◽  
Vol 37 (4) ◽  
pp. 1470-1482 ◽  
Author(s):  
Nina Schultz ◽  
Elin Byman ◽  
Malin Fex ◽  
Malin Wennström

Amylin, a pancreatic β-cell-derived peptide hormone, forms inclusions in brain microvessels of patients with dementia who have been diagnosed with type 2 diabetes and Alzheimer’s disease. The cellular localization of these inclusions and the consequences thereof are not yet known. Using immunohistochemical staining of hippocampus and parahippocampal cortex from patients with Alzheimer’s disease and non-demented controls, we show that amylin cell inclusions are found in pericytes. The number of amylin cell inclusions did not differ between patients with Alzheimer’s disease and controls, but amylin-containing pericytes displayed nuclear changes associated with cell death and reduced expression of the pericyte marker neuron-glial antigen 2. The impact of amylin on pericyte viability was further demonstrated in in vitro studies, which showed that pericyte death increased in presence of fibril- and oligomer amylin. Furthermore, oligomer amylin increased caspase 3/7 activity, reduced lysate neuron-glial antigen 2 levels and impaired autophagy. Our findings contribute to increased understanding of how aggregated amylin affects brain vasculature and highlight amylin as a potential factor involved in microvascular pathology in dementia progression.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Fátima Cuadrado ◽  
Adoración Antolí ◽  
Juan A. Moriana ◽  
Julia Vacas

Abstract The prevalence of negative representations of Alzheimer’s disease (AD) reinforces the stigma and negative attitudes toward this dementia. To mitigate these negative views, campaigns have been launched by several organizations. This study aims to explore the effect of framing in AD campaigns on attitude change. For this purpose, several posters were designed with framed messages defining dementia (dualism, unity, and control) and 189 participants were shown the posters. In order to analyze the effect of the different frames, a repeated-measures design was used, in which attitudes toward dementia were measured three times. The impact of the campaign and the emotions it produced were recorded as well as the effects of the participants’ experience with AD and the importance they attached to it. Posters with unity-framed messages produced a positive and lasting change in attitudes toward dementia and higher levels of happiness, while dualism-framed messages had a greater impact and produced feelings of sadness, anger, and fear but did not change the audience’s attitude. Although more research is needed on persuasion in campaigns, the findings can serve to guide the design of AD campaigns.


2021 ◽  
Author(s):  
Sarah Garder ◽  
Catharine Brady ◽  
Cameron Keeton ◽  
Anuj K Yadav ◽  
Sharath C Mallojjala ◽  
...  

<p>In the context of deep-tissue disease biomarker detection and analyte sensing of biologically relevant species, the impact of photoacoustic imaging has been profound. However, most photoacoustic imaging agents to date are based on the repurposing of existing fluorescent dye platforms that exhibit non-optimal properties for photoacoustic applications (e.g., high fluorescence quantum yield). Herein, we introduce two effective modifications to the hemicyanine dye to afford PA-HD, a new dye scaffold optimized for photoacoustic probe development. We observed a significant increase in the photoacoustic output, representing an increase in sensitivity of 4.8-fold and a red-shift of the λ<sub>abs</sub> from 690 nm to 745 nm to enable ratiometric imaging. Moreover, to demonstrate the generalizability and utility of our remodeling efforts, we developed three probes using common analyte-responsive triggers for beta-galactosidase activity (PA-HD-Gal), nitroreductase activity (PA-HD-NTR), and hydrogen peroxide (PA-HD-H<sub>2</sub>O<sub>2</sub>). The performance of each probe (responsiveness, selectivity) was evaluated <i>in vitro</i> and <i>in cellulo</i>. To showcase the enhance properties afforded by PA-HD for <i>in vivo</i> photoacoustic imaging, we employed an Alzheimer’s disease model to detect H<sub>2</sub>O<sub>2</sub>. In particular, the photoacoustic signal at 735 nm in the brains of 5xFAD mice (a murine model of Alzheimer’s disease) increased by 1.72 ± 0.20-fold relative to background indicating the presence of oxidative stress, whereas the change in wildtype mice was negligible (1.02 ± 0.14). These results were confirmed via ratiometric calibration which was not possible using the parent HD platform.</p>


2020 ◽  
Author(s):  
Simone Mwenda Crivelli ◽  
Qian Luo ◽  
Jo Stevens ◽  
Caterina Giovagnoni ◽  
Daan van Kruining ◽  
...  

Abstract Background: Deregulation of ceramide and sphingomyelin levels have been suggested to contribute to the pathogenesis of Alzheimer’s disease (AD). Ceramide transfer proteins (CERTs) are ceramide carriers, crucial for ceramide and sphingomyelin balance in cells. Extracellular forms of CERTs co-localize with amyloid-β (Aβ) plaques in AD brains. To date, the significance of these observations for the pathophysiology of AD remains uncertain.Methods: The plasmid expressing CERTL, the long isoform of CERTs, was used to study the interaction of CERTL with amyloid precursor protein (APP) by co-immunoprecipitation and immunofluorescence in HEK cells. The recombinant CERTL protein was employed to study interaction of CERTL with amyloid-β (Aβ), Aβ aggregation process in presence of CERTL, and the resulting changes in Aβ toxicity in neuroblastoma cells. CERTL was overexpressed in neurons by adeno associated virus (AAV) in a familial mouse model of familial AD (5xFAD). Ten weeks after transduction animal were challenged with behavior tests for memory, anxiety and locomotion. At week twelve brains were investigated for sphingolipid levels by mass spectrometry, plaques and neuroinflammation by immunohistochemistry, gene expression and/or immunoassay.Results: Here, we report that CERTL, binds to APP, modifies Aβ aggregation and reduces Aβ neurotoxicity in vitro. Furthermore, we show that intracortical injection of AAV, mediating the expression of CERTL, decreases levels of ceramide d18:1/16:0 and increases sphingomyelin levels in the brain of male transgenic mice, modelling familial AD (5xFAD). CERTL in vivo over-expression has a mild effect on animal locomotion and decreases Aβ formation and modulates microglia by decreasing their pro-inflammatory phenotype.Conclusion: Our results demonstrate a crucial role of CERTL in regulating ceramide levels in the brain, in amyloid plaque formation and neuroinflammation, thereby opening research avenues for therapeutic targets of AD and other neurodegenerative diseases.


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