Cognitive decline due to Alzheimer's disease (AD) is frequent in the geriatric population, which has been disproportionately affected by the COVID-19 pandemic. In this study, we investigated the ...levels of angiotensin-converting enzyme 2 (ACE2), a regulator of the renin-angiotensin system and the main entry receptor of SARS-CoV-2 in host cells, in postmortem parietal cortex samples from two independent AD cohorts, totalling 142 persons. Higher concentrations of ACE2 protein (p < 0.01) and mRNA (p < 0.01) were found in individuals with a neuropathological diagnosis of AD compared to age-matched healthy control subjects. Brain levels of soluble ACE2 were inversely associated with cognitive scores (p = 0.02) and markers of pericytes (PDGFRbeta, p = 0.02 and ANPEP, p = 0.007), but positively correlated with concentrations of soluble amyloid-beta peptides (Abeta) (p = 0.01) and insoluble phospho-tau (S396/404, p = 0.002). However, no significant differences in ACE2 were observed in the 3xTg-AD mouse model of tau and Abeta neuropathology. Results from immunofluorescence and Western blots showed that ACE2 protein is predominantly localized in microvessels in the mouse brain whereas it is more frequently found in neurons in the human brain. The present data suggest that higher levels of soluble ACE2 in the human brain may contribute to AD, but their role in CNS infection by SARS-CoV-2 remains unclear. Keywords: ACE2, Alzheimer's disease, Cognitive dysfunction, Blood-brain barrier, Neuropathology
Abstract
Prime editing enables the introduction of precise point mutations, small insertions, or short deletions without requiring donor DNA templates. However, efficiency remains a key challenge in ...a broad range of human cell types. In this work, we design a robust co-selection strategy through coediting of the ubiquitous and essential sodium/potassium pump (Na
+
/K
+
ATPase). We readily engineer highly modified pools of cells and clones with homozygous modifications for functional studies with minimal pegRNA optimization. This process reveals that nicking the non-edited strand stimulates multiallelic editing but often generates tandem duplications and large deletions at the target site, an outcome dictated by the relative orientation of the protospacer adjacent motifs. Our approach streamlines the production of cell lines with multiple genetic modifications to create cellular models for biological research and lays the foundation for the development of cell-type specific co-selection strategies.
Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by changes in cognitive and behavioral functions. With the exception or rare mutations in PSEN and APP genes causing ...early-onset autosomal dominant AD (EOADAD), little is known about the genetic factors that underlie the vast majority (>95%) of early onset AD (EOAD) cases. We have previously identified copy number variations (CNVs) in microRNA genes in patients with EOAD, including a duplication of the MIR-138-2 gene. Overexpression of miR-138 in cultured cells increased Aβ production and tau phosphorylation, similar to what is seen in AD brain. In this study, we sought to determine if miR-138 overexpression could recapitulate certain features of disease
in non-transgenic mice. A mild overexpression of pre-miR-138 in the brain of C57BL/6J wildtype mice altered learning and memory in a novel object recognition test and in the Barnes Maze. Increased levels of anxiety were also observed in the open-field test. MiR-138 upregulation
caused an increase in endogenous Aβ42 production as well as changes in synaptic and inflammation markers. Tau expression was significantly lower with no overt effects on phosphorylation. We finally observed that Sirt1, a direct target of miR-138 involved in Aβ production, learning and memory as well as anxiety, is decreased following miR-138 overexpression. In sum, this study further strengthens a role for increased gene dosage of MIR-138-2 gene in modulating AD risk, possibly by acting on different biological pathways. Further studies will be required to better understand the role of CNVs in microRNA genes in AD and related neurodegenerative disorders.
In the past decade, several groups have reported that microRNAs (miRNAs) can participate in the regulation of tau protein at different levels, including its expression, alternative splicing, ...phosphorylation, and aggregation. These observations are significant, since the abnormal regulation and deposition of tau is associated with nearly 30 neurodegenerative disorders. Interestingly, miRNA profiles go awry in tauopathies such as Alzheimer's disease, progressive supranuclear palsy, and frontotemporal dementia. Understanding the role and impact of miRNAs on tau biology could therefore provide important insights into disease risk, diagnostics, and perhaps therapeutics. In this Perspective article, we discuss recent advances in miRNA research related to tau. While proof-of-principle studies hold promise, physiological validation remains limited. To help fill this gap, we describe herein a pure tauopathy mouse model deficient for the miR-132/212 cluster. This miRNA family is strongly downregulated in human tauopathies and shown to regulate tau
in vitro
and
in vivo
. No significant differences in survival, motor deficits or body weight were observed in PS19 mice lacking miR-132/212. Age-specific effects were seen on tau expression and phosphorylation but not aggregation. Moreover, various miR-132/212 targets previously implicated in tau modulation were unaffected (GSK-3β, Foxo3a, Mapk1, p300) or, unexpectedly, reduced (Mapk3, Foxo1, p300, Calpain 2) in miR-132/212-deficient PS19 mice. These observations highlight the challenges of miRNA research in living models, and current limitations of transgenic tau mouse models lacking functional miRNA binding sites. Based on these findings, we finally recommend different strategies to better understand the role of miRNAs in tau physiology and pathology.
Altered microRNA (miRNA) expression is a common feature of Huntington's disease (HD) and could participate in disease onset and progression. However, little is known about the underlying causes of ...miRNA disruption in HD. We and others have previously shown that mutant Huntingtin binds to Ago2, a central component of miRNA biogenesis, and disrupts mature miRNA levels. In this study, we sought to determine if miRNA maturation per se was compromised in HD. Towards this end, we characterized major miRNA biogenesis pathway components and miRNA maturation products (pri-miRNA, pre-miRNA, and mature) in human HD (N = 41, Vonsattel grades HD2-4) and healthy control (N = 25) subjects. Notably, the striatum (putamen) and cortex (BA39) from the same individuals were analyzed in parallel. We show that Ago2, Drosha, and Dicer were strongly downregulated in human HD at the early stages of the disease. Using a panel of HD-related miRNAs (miR-10b, miR-196b, miR-132, miR-212, miR-127, miR-128), we uncovered various types of maturation defects in the HD brain, the most prominent occurring at the pre-miRNA to mature miRNA maturation step. Consistent with earlier findings, we provide evidence that alterations in autophagy could participate in miRNA maturation defects. Notably, most changes occurred in the striatum, which is more prone to HTT aggregation and neurodegeneration. Likewise, we observed no significant alterations in miRNA biogenesis in human HD cortex and blood, strengthening tissue-specific effects. Overall, these data provide important clues into the underlying mechanisms behind miRNA alterations in HD-susceptible tissues. Further investigations are now required to understand the biological, diagnostic, and therapeutic implications of miRNA/RNAi biogenesis defects in HD and related neurodegenerative disorders. Keywords: Huntington's disease, microRNA, Ago2, Dicer, RNAi, Biogenesis, Autophagy
Le corépresseur nucléaire NCOR1 est impliqué dans la régulation transcriptionnelle en interagissant avec les récepteurs à hormones thyroïdiennes et rétinoïques ainsi qu’avec les facteurs de ...transcription AP-1 et NF-κB au niveau des gènes cibles impliqués dans la réponse inflammatoire intestinale. Par une approche d’immunoprécipitation (IP) couplée à la spectrométrie de masse, CHD8 a été découverte pour agir de manière complémentaire à NCOR1. CHD8 est impliquée dans le remodelage de la chromatine et dans la régulation du cycle cellulaire. Ainsi, le projet de recherche visait à comprendre l’interaction et les rôles fonctionnels de CHD8 et de NCOR1 ainsi que l’impact physiologique de la perte d’expression de NCOR1 face à un stress épithélial. Pour commencer, nous avons confirmé l’interaction entre CHD8 et NCOR1 dans différents types cellulaires tels que les 18Co, Caco-2/15 et HT-29. Ensuite, nous avons diminué l’expression de NCOR1 et CHD8 dans les cellules HT-29 et Caco-2/15 à l’aide de shRNA et nous avons observé une diminution de croissance cellulaire intermédiaire pour la perte de CHD8 comparativement à une diminution plus drastique pour NCOR1. L’effet intermédiaire sur la croissance cellulaire peut être dû à un effet de compensation par la petite forme de CHD8 (CHD8S) puisque le shRNA utilisé cible uniquement la grande forme de CHD8 (CHD8L). Avec cette diminution commune de croissance cellulaire, une question s’est imposée à savoir quelle est l’implication de l’interaction entre CHD8 et NCOR1 dans ce phénomène. Nous avons séparé NCOR1 en protéines correspondant à ces différents domaines et par IP suivies d’immunobuvardages, nous avons déterminé que le premier domaine de répression de NCOR1 (RD1) interagissait avec la forme complète de CHD8 au niveau du noyau. Nous avons ensuite utilisé un modèle murin où il y a une perte d’expression de NCOR1 (NCOR1ΔE11ΔCEI) avec l’aide d’un modèle où la Cre-recombinase est exprimée sous le promoteur de la villine. Nous avons ensuite traité les souris NCOR1ΔE11ΔCEI et contrôles au DSS 3% afin d’induire des lésions aux cellules épithéliales intestinales. Ceci permet l’étude de la suceptibilité au DSS des souris contrôles et NCOR1ΔE11ΔCEI. Ainsi, CHD8 et NCOR1 ont des rôles fonctionnels communs qui pourrait être attribué à leur interaction, CHD8-NCOR1 (RD1). Cette nouvelle mécanistique permettrait donc de réguler la transcription de certains gènes cibles impliqués dans le cancer colorectal.
Objectives: Suffering is intimately linked to the experience of illness, and its relief is a mandate of medicine. Advances in knowledge around terminal illness have enabled better management of the ...somatic dimension. Nevertheless, there is what can be called “non-somatic” suffering which in some cases may take precedence. Inspired by Paul Ricoeur's thinking on human suffering, our aim in this qualitative study was to better understand the experience of non-somatic suffering. Methods: Semi-structured interviews were conducted with 19 patients. The results were qualitatively analyzed following a continuous comparative analysis approach inspired by grounded theory. Results: Three key themes synthesize the phenomenon: “the being enduring the suffering”, “the being whose agency is constrained”, and “the being in relationship with others.” The first describes what patients endure, the shock and fears associated with their own finitude, and the limits of what can be tolerated. The second refers to the experience of being restricted and of mourning the loss of their capacity to act. The last describes a residual suffering related to their interactions with others, that of loneliness and of abandoning their loved ones, two dimensions that persist even when they have accepted their own death. Conclusions: Non-somatic suffering can be multifarious, even when minimized by the patient. When evaluating suffering, we must keep in mind that patients can reach a “breaking point” that signals the state of unbearable suffering. In managing it, we probably need to make more room for family and friends, as well as a posture of caring based more on presence and listening.
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NUK, OILJ, SAZU, UKNU, UL, UM, UPUK, VSZLJ
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