Faculty Bibliography

BACKGROUND/AIMS/OBJECTIVE:Ouabain, a well-known plant-derived toxin, is also a hormone found in mammals at nanomolar levels that binds to a site located in the a-subunit of Na⁺,K⁺-ATPase. Our main goal was to understand the physiological roles of ouabain. Previously, we found that ouabain increases the degree of tight junction sealing, GAP junction-mediated communication and ciliogenesis. Considering our previous results, we investigated the effect of ouabain on adherens junctions. METHODS:We used immunofluorescence and immunoblot methods to measure the effect of 10 nM ouabain on the cellular and nuclear content of E-cadherin, β-catenin and γ-catenin in cultured monolayers of Marin Darby canine renal cells (MDCK). We also studied the effect of ouabain on adherens junction biogenesis through sequential Ca²⁺ removal and replenishment. Then, we investigated whether c-Src and ERK1/2 kinases are involved in these responses. RESULTS:Ouabain enhanced the cellular content of the adherens junction proteins E-cadherin, β-catenin and γ-catenin and displaced β-catenin and γ-catenin from the plasma membrane into the nucleus. Ouabain also increased the expression levels of E-cadherin and β-catenin in the plasma membrane after Ca²⁺ replenishment. These effects on adherens junctions were sensitive to PP2 and PD98059, suggesting that they depend on c-Src and ERK1/2 signaling. The translocation of β-catenin and γ-catenin into the nucleus was specific because ouabain did not change the localization of the tight junction proteins ZO-1 and ZO-2. Moreover, in ouabain-resistant MDCK cells, which express a Na⁺,K⁺-ATPase α1-subunit with low affinity for ouabain, this hormone was unable to regulate adherens junctions, indicating that the ouabain receptor that regulates adherens junctions is Na⁺,K⁺-ATPase. CONCLUSION/CONCLUSIONS:Ouabain (10 nM) upregulated adherens junctions. This novel result supports the proposition that one of the physiological roles of this hormone is the modulation of cell contacts.

In order to automatically process qPCR raw data, we present the tool "Do my qPCR calculation". We offer a website to automatically calculate the data normalization and represent the different samples graphically in an Excel file. This tool is also available on Github for installation and local use with or without web interface.

Introduction: Noncoding small RNAs in the retina regulate gene expression by targeting and repressing mRNA. Small RNAs are secreted in extracellular vesicles (EVs). Analysis of EVs released from developing retinal tissue is an essential step in elucidating the role of EV molecular cargo and signalling during retinogenesis. A number of canonical genes are associated with retinal cell fate determination during development, but EV-mediated gene regulation in the retinal microenvironment remains undefined. In this study, we characterize the microRNA, tRNA, and piRNA composition of EVs secreted from human induced pluripotent stem cell (hiPSCs) - derived 3D retinas at three developmental time points that correlate with hallmarks of retinal cell differentiation and lamination in vivo.
Method(s): Retinal organoids were generated from hiPSCs. We selected three developmental time points (day 42, 63 and 90) that represent distinctive stages during normal retinal cell fate specification and lamination. We analysed the release rate, concentration, morphology and content (miRNA, tRNA and pi- RNA) of EVs released from human hiPSCs-derived 3D retinas.
Result(s): The genetic signalling, developmental time course and morphogenesis of these retinal organoids were comparable to those of developing human retinas in vivo. According to Gene Ontology analysis, miRNA targets at the earliest stage of development were more relevant to early differentiation and cell morphogenesis, whereas miRNA targets at the later stages were more relevant to cell proliferation, cell differentiation, and cell migration. Summary/Conclusion: For the first time, this work demonstrates the rate of release and concentration of EVs from developing hiPSC-derived 3D retinal tissue. We report a large variety of small RNAs in EVs from hiPSC-derived 3D retinas, including miRNAs, tRNAs and piRNAs. The full range of small RNAs detected in our EVs may act as regulatory elements to modulate gene activity and may serve as biomarkers of normal development. This work represents the first sequencing analysis of small RNA species contained in hiPSCderived 3D retinas and their released EVs

Behavioral choices made by the brain during stress depend on glucocorticoid and brain-derived neurotrophic factor (BDNF) signaling pathways acting in synchrony in the mesolimbic (reward) and corticolimbic (emotion) neural networks. Deregulated expression of BDNF and glucocorticoid receptors in brain valuation areas may compromise the integration of signals. Glucocorticoid receptor phosphorylation upon BDNF signaling in neurons represents one mechanism underlying the integration of BDNF and glucocorticoid signals that when off balance may lay the foundation of maladaptations to stress. Here, we propose that BDNF signaling conditions glucocorticoid responses impacting neural plasticity in the mesocorticolimbic system. This provides a novel molecular framework for understanding how brain networks use BDNF and glucocorticoid signaling contingencies to forge receptive neuronal fields in temporal domains defined by behavioral experience, and in mood disorders.

Background:gene encoding a voltage-gated sodium channel alpha-II subunit Nav1.2 are associated with neurological disorders such as epilepsy, autism spectrum disorders, intellectual disability, and schizophrenia. However, causal relationships and pathogenic mechanisms underlying these neurological defects, especially social and psychiatric features, remain to be elucidated. Methods:in a comprehensive test battery including open field, elevated plus maze, light-dark box, three chambers, social dominance tube, resident-intruder, ultrasonic vocalization, and fear conditioning tests. We further monitored the effects of the positive allosteric modulator of AMPA receptors CX516 on these model mice. Results:mice, with an increase in the gamma band. Conclusions:mice exhibit a spectrum of phenotypes commonly observed in models of schizophrenia and autism spectrum disorder. Treatment with the CX516 ampakine, which ameliorates hyperactivity in these mice, could be a potential therapeutic strategy to rescue some of the disease phenotypes.

[This corrects the article DOI: 10.1371/journal.pone.0215571.].

Many brain functions frequently change across a life span in response to new experience, the rewiring of neural circuits, homeostatic factors, and environmental events. Extracellular signals can promote rapid responses in gene expression and protein synthesis that trigger growth and plasticity in the nervous system. A key component is activity-dependent events and their participation in synaptic function. These responses are required for long-lasting effects in synaptic plasticity associated with learning and memory. The neurotrophin brain-derived neurotrophic factor (BDNF), discovered in 1982, is well established as a prominent molecule responsible for inducing synaptogenesis, dendritic growth, and long-term potentiation. This volume of the Neuromethods Series is dedicated to the methods that have allowed to study the many potential mechanisms whereby BDNF signaling accounts for its many physiological effects.
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