7-ketocholesterol stimulates differentiation of lens epithelial cells

PURPOSE: To establish if oxysterols stimulate differentiation of lens epithelial cells (LEC). METHODS: Primary cultures of lens epithelial cells were incubated with 7-ketocholesterol (7-keto), 25-hydroxycholesterol (25-OH) or cholesterol at 10 microg/ml for 10 days. Cells incubated with 100 ng/ml basic fibroblast growth factor (b-FGF) were used as positive controls for differentiation. The expression of the differentiation marker p57KIP2, proliferation marker PCNA (Proliferating Cell Nuclear Antigen) and fibers specific proteins gamma-crystallin, CP49, MIP26 following treatment with oxysterols was determined by western blot. Differentiation into fiber cells was further confirmed by counting the number of lentoid bodies formed following incubation with 7-keto. RESULTS: LEC incubated with 7-keto presented higher levels of p57KIP2 and showed expression of fiber specific proteins such as MIP26 and CP49, compared to cells incubated with 25-OH or cholesterol. The differentiation marker p57KIP2 increased over time for cells incubated with 7-keto while there was a decline on the amount of the proliferation marker PCNA. The expression of the fiber specific proteins gamma-crystallin, MIP26 and CP49 was detected after 5 days of incubation with 7-keto. Differentiation was accompanied by a seven-fold increase in the number of lentoid bodies formed. CONCLUSIONS: Results show for the first time that 7-keto inhibits proliferation and stimulates differentiation of lens epithelial cells into fiber cells. The presence of 7-keto in the lens may disrupt the highly regulated differentiation program of LEC, compromising normal lens growth and transparenc

High glucose down-regulates intercellular communication in retinal endothelial cells by enhancing degradation of connexin 43 by a proteasome-dependent mechanism

Intercellular communication through gap junctions (GJIC) is most likely relevant to maintaining the integrity of the blood-retinal barrier. In this study, we investigated the mechanism whereby high glucose enhances degradation of connexin 43 (Cx43), thus contributing to a decrease in GJIC. The levels of Cx43 in bovine retinal endothelial cells exposed to high glucose (25 mm) decreased about 50% as compared with controls (5.5 mm glucose). Consistently, the half-life of the protein decreased from 2.3 to 1.9 h. The proteasome inhibitors MG132 and lactacystin prevented the loss of Cx43 induced by high glucose and extended Cx43 half-life. The amount of phosphorylated Cx43 increased in high glucose and after proteasome inhibition. Scrape-loading dye transfer experiments show that high glucose is associated to a decrease of 40% in GJIC. Significantly, this reduction can be reversed by proteasome inhibitors. The decrease in GJIC in cells exposed to high glucose is associated with a loss of Cx43 from the plasma membrane, as demonstrated by immunofluorescence and biotinylation of cell-surface proteins. Results indicate that increased phosphorylation of Cx43 under high glucose is the mechanism targeting Cx43 for degradation by a proteasome-dependent mechanism. Increased degradation of Cx43 and reduction of GJIC in high glucose may be of physiological importance by contributing to endothelial cell dysfunction associated with the breakdown of the blood-retinal barrier in diabetic retinopath

7-Ketocholesterol modulates intercellular communication through gap-junction in bovine lens epithelial cells

BACKGROUND: Connexin43 (Cx43) is an integral membrane protein that forms intercellular channels called gap junctions. Intercellular communication in the eye lens relies on an extensive network of gap junctions essential for the maintenance of lens transparency. The association of Cx43 with cholesterol enriched lipid raft domains was recently demonstrated. The objective of this study is to assess if products of cholesterol oxidation (oxysterols) affect gap junction intercellular communication (GJIC). RESULTS: Primary cultures of lens epithelial cells (LEC) were incubated with 7-ketocholesterol (7-Keto), 25-hydroxycholesterol (25-OH) or cholesterol and the subcellular distribution of Cx43 was evaluated by immunofluorescence confocal microscopy. The levels of Cx43 present in gap junction plaques were assessed by its insolubility in Triton X-100 and quantified by western blotting. The stability of Cx43 at the plasma membrane following incubation with oxysterols was evaluated by biotinylation of cell surface proteins. Gap junction intercellular communication was evaluated by transfer of the dye Lucifer yellow. The results obtained showed that 7-keto induces an accumulation of Cx43 at the plasma membrane and an increase in intercellular communication through gap junction. However, incubation with cholesterol or 25-OH did not lead to significant alterations on subcellular distribution of Cx43 nor in intercellular communication. Data further suggests that increased intercellular communication results from increased stability of Cx43 at the plasma membrane, presumably forming functional gap-junctions, as suggested by decreased solubility of Cx43 in 1% Triton X-100. The increased stability of Cx43 at the plasma membrane seems to be specific and not related to disruption of endocytic pathway, as demonstrated by dextran uptake. CONCLUSIONS: Results demonstrate, for the first time, that 7-keto induces an increase in gap junction intercellular communication, that is most likely due to an increased stability of protein at the plasma membrane and to increased abundance of Cx43 assembled in gap junction plaques

Análise de viabilidade técnico-econômica de sistema fotovoltaico conectado à rede para o jardim botânico de Brasília com foco na conscientização ambiental utilizando fontes renováveis de energia

Trabalho de conclusão de curso (graduação)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2019.Neste trabalho, é realizado o estudo de viabilidade técnica e econômica de um projeto de sistema fotovoltaico que, apesar de estar conectado à rede, não possui disposição física semelhante aos projetos mais convencionais de energia solar fotovoltaica, geralmente em telhados ou em estruturas instaladas diretamente no solo. Para tornar o conhecimento em fontes renováveis de energia mais interessante e mais palpável, optou-se por projetar um sistema fotovoltaico cujo formato lembrasse uma orquídea tradicional da flora de Brasília. A fim de entender quais as melhores configurações de módulos e inversores, foram realizadas simulações por meio de softwares especializados em sistemas fotovoltaicos, sendo esse o grande desafio da análise de viabilidade técnica. Para este projeto, foram utilizados microinversores, dada a baixa potência dos módulos e a necessidade de se ter um sistema menos robusto e que a interferência das piores orientações não comprometesse as orientações mais favoráveis. Para a análise de viabilidade econômica se baseou em indicadores de retorno de projetos e teve como grande desafio contornar a baixa potência dos módulos e suas orientações (inclinação e azimute) mais diversas. O principal público alvo deste projeto são as crianças que realizam visitas ao jardim botânico, sejam elas guiadas pelos pais ou orientadas pelas suas respectivas escolas. Fazer uma criança entender que é possível gerar energia de forma limpa e renovável, tornando-a mais susceptível a acreditar num mundo sustentável é o grande objetivo deste sistema. Dito isso, os indicadores de viabilidade econômica não são favoráveis quando comparados a um sistema padrão instalado em um telhado, mas seu ganho socioambiental pode nivelar a atratividade deste sistema.In this paper an analysis of the technical and economic viability of a photovoltaic system project, which, although its grid connected, doesn’t have a physical disposition such as the more standard photovoltaic systems, usually integrated to rooftops or in structures attached directly to the ground. In order to make the knowledge of renewable energy sources more interesting and palpable, it was decided to design a photovoltaic system whose shape would refer to a tradition orchid of Brasília’s flora. In order to understand the best configurations of modules and inverters, simulations were performed using specialized photovoltaic software, which is the great challenge of the technical viability analysis. For this project, microinverters were used, given the low power of the photovoltaic modules, the need to have a less robust system and the interference of the worst orientations don’t compromise the most favorable ones. The economic viability analysis was based on project return indicators and it was a great challenge to surpass the low power of the photovoltaic modules and their diverse orientations (inclination and azimuth). The main target audience for this project are the children visiting the Brasilia’s Botanical Garden, whether they are guided by their parents or by their respective schools. Making a child understand that it’s possible to generate energy in a clean and renewable way, making them more likely to believe in a sustainable world is the ultimate goal of this project. That said, the economic viability indicators are not favorable when compared to a standard roof mounted system, but its social and environmental gain may even the odds

Signalling mechanisms that regulate metabolic profile and autophagy of acute myeloid leukaemia cells

Acute myeloid leukaemia (AML) comprises a heterogeneous group of hematologic neoplasms characterized by diverse combinations of genetic, phenotypic and clinical features representing a major challenge for the development of targeted therapies. Metabolic reprogramming, mainly driven by deregulation of the nutrient-sensing pathways as AMPK, mTOR and PI3K/AKT, has been associated with cancer cells, including AML cells, survival and proliferation. Nevertheless, the role of these metabolic adaptations on the AML pathogenesis is still controversial. In this work, the metabolic status and the respective metabolic networks operating in different AML cells (NB-4, HL-60 and KG-1) and their impact on autophagy and survival was characterized. Data show that whereas KG-1 cells exhibited preferential mitochondrial oxidative phosphorylation metabolism with constitutive co-activation of AMPK and mTORC1 associated with increased autophagy, NB-4 and HL-60 cells displayed a dependent glycolytic profile mainly associated with AKT/mTORC1 activation and low autophagy flux. Inhibition of AKT is disclosed as a promising therapeutical target in some scenarios while inhibition of AMPK and mTORC1 has no major impact on KG-1 cells' survival. The results highlight an exclusive metabolic profile for each tested AML cells and its impact on determination of the anti-leukaemia efficacy and on personalized combinatory therapy with conventional and targeted agents.This work was developed under the scope of the project NORTE‐01‐0145‐FEDER‐000013, supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER), and by FEDER, through the Competitiveness Factors Operational Programme (COMPETE), and by National funds, through the Foundation for Science and Technology (FCT), under the scope of the project POCI‐01‐0145‐FEDER‐007038. OP and BSM are supported by fellowships from the Fundação para a Ciência e Tecnologia (FCT, Portugal) (SFRH/BD/52292/2013 and SFRH/BPD/90533/2012, respectively)info:eu-repo/semantics/publishedVersio

A Conserved LIR Motif in Connexins Mediates Ubiquitin-Independent Binding to LC3/GABARAP Proteins

This research was supported by the European Regional Development Fund (ERDF) through the Operational Program for Competitiveness Factors (COMPETE) [under the projects PAC “NETDIAMOND” POCI-01-0145-FEDER-016385; HealthyAging2020 CENTRO-01-0145-FEDER-000012-N2323; POCI-01-0145-FEDER-007440, CENTRO-01-0145-FEDER-032179, CENTRO-01-0145-FEDER-032414,FCTUID/NEU/04539/2013 and ID/NEU/04539/2019]. This research is based upon work from COST Action (PROTEOSTASIS BM1307), supported by COST (European Cooperation in Science and Technology).S.C. was supported by Action BM1307 – 39607 from COST Action PROTEOSTASIS BM1307, T.M.R.-R. was supported by PD/BD/52294/2013 from Fundação para a Ciência e a Tecnologia (FCT). C.A. was supported by a DOC Fellowship of the Austrian Academy of Sciences.Gap junctions (GJ) are specialized cell-cell contacts formed by connexins (Cxs), which provide direct communication between adjacent cells. Cx43 ubiquitination has been suggested to induce the internalization of GJs, as well as the recruitment of the autophagy receptor p62 to mediate binding to LC3B and degradation by macroautophagy. In this report, we describe a functional LC3 interacting region (LIR), present in the amino terminal of most Cx protein family members, which can mediate the autophagy degradation of Cx43 without the need of ubiquitin. Mutation of the LIR motif on Cx37, Cx43, Cx46 and Cx50 impairs interaction with LC3B and GABARAP without compromising protein ubiquitination. Through in vitro protein-protein interaction assays, we demonstrate that this LIR motif is required for the binding of Cx43 to LC3B and GABARAP. Overall, our findings describe an alternative mechanism whereby Cxs interact with LC3/GABARAP proteins, envisioning a new model for the autophagy degradation of connexins.publishersversionpublishe

Flavonoids as Modulators of Synaptic Plasticity: Implications for the Development of Novel Therapeutic Strategies for Healthy Lifestyle

Flavonoids are potential group of phytochemicals found in normal diets capable of mediating improvements in cognition and may reverse age-related declines in memory. Aging is associated with alteration of hippocampal synaptic plasticity and contribute to decline in cognitive functions. The current studies are directed at a greater understanding of how and why the brain modifies synaptic strength with dietary-derived phytochemicals (flavonoids) and age-related declines in cognitive functions (such as learning and memory). Flavonoids modulate neuronal function and thereby influence cognition. In addition, it has been suggested that flavonoids may delay the development of Alzheimer’s disease-like pathology, anxiety, and depression disorders, suggesting a novel therapeutic strategy. Emerging evidence suggest that flavonoids are modulators of signaling pathways critical for controlling synaptic plasticity in the brain. For example, phosphatidylinositol-3 kinase (PI3K)/Akt, mitogen-activated protein kinase, protein kinase C, pathways could be involved Ca2+ signaling. Significants questions such as: (i) How does flavonoids affect plasticity? (ii) What receptors are modulating by flavonoids and how are they regulated? (iii) Do flavonoids have a neuroprotective effect in aging? are asked

Chromosomal distribution of microsatellite repeats in Amazon cichlids genome (Pisces, Cichlidae)

Fish of the family Cichlidae are recognized as an excellent model for evolutionary studies because of their morphological and behavioral adaptations to a wide diversity of explored ecological niches. In addition, the family has a dynamic genome with variable structure, composition and karyotype organization. Microsatellites represent the most dynamic genomic component and a better understanding of their organization may help clarify the role of repetitive DNA elements in the mechanisms of chromosomal evolution. Thus, in this study, microsatellite sequences were mapped in the chromosomes of Cichla monoculus Agassiz, 1831, Pterophyllum scalare Schultze, 1823, and Symphysodon discus Heckel, 1840. Four microsatellites demonstrated positive results in the genome of C. monoculus and S. discus, and five demonstrated positive results in the genome of P. scalare. In most cases, the microsatellite was dispersed in the chromosome with conspicuous markings in the centromeric or telomeric regions, which suggests that sequences contribute to chromosome structure and may have played a role in the evolution of this fish family. The comparative genome mapping data presented here provide novel information on the structure and organization of the repetitive DNA region of the cichlid genome and contribute to a better understanding of this fish family's genome. © Carlos Henrique Schneider et al

Micro-RNA Analysis in Pulmonary Arterial Hypertension: Current Knowledge and Challenges

Pulmonary arterial hypertension (PAH) is a rare, chronic disease of the pulmonary vasculature that is associated with poor outcomes. Its pathogenesis is multifactorial and includes micro-RNA (miRNA) deregulation. The understanding of the role of miRNAs in PAH is expanding quickly, and it is increasingly difficult to identify which miRNAs have the highest translational potential. This review summarizes the current knowledge of miRNA expression in PAH, discusses the challenges in miRNA analysis and interpretation, and highlights 4 promising miRNAs in this field (miR-29, miR-124, miR-140, and miR-204)