Protective activity of hesperidin and lipoic acid against sodium arsenite acute toxicity in mice

The objective of the present work was to evaluate the toxic effects of sodium arsenite, As(III), in mice and the protective effect of 2 antioxidants, hesperidin and lipoic acid, against the observed As(III)-induced toxicity. In each study, mice were assigned to 1 of 4 groups: control, antioxidant, antioxidant + arsenite, and arsenite. Animals were first injected with the vehicle or 25 mg antioxidant/kg BW. After 30 minutes they received an injection of 10 mg arsenite/kg BW or 0.9% NaCl. Two hours after the first injection, the liver, kidney, and testis were collected for histological evaluation. Liver samples were also taken for quantification of arsenic. In mice exposed only to As(III), various histopathological effects were observed in the liver, kidneys, and testes. In mice pretreated with either hesperidin or lipoic acid, a reduction of histopathologic effects on the liver and kidneys was observed. No protective effects were observed in the testes for either of the 2 studied antioxidants. In conclusion, hesperidin and lipoic acid provided protective effects against As(III)-induced acute toxicity in the liver and kidneys of mice. These compounds may potentially play an important role in the protection of populations chronically exposed to arsenic.info:eu-repo/semantics/publishedVersio

Soft culture substrates favor stem-like cellular phenotype and facilitate reprogramming of human mesenchymal stem/stromal cells (hMSCs) through mechanotransduction

Fundação para a Ciência e a Tecnologia) - FCT - grant FCT-UID/NEU/04539/2019. European Regional Development Fund (ERDF/FEDER) through the Operational Program Competitiveness Factors (Programa Operacional Factores de Competitividade) - COMPETE - funding through Project 'Stem cell based platforms for Regenerative and Therapeutic Medicine', Centro-07-ST24-FEDER-002008. M.G. acknowledges funding by the ERDF/FEDER through COMPETE and by national funds by FCT through grant FCOMP-01-0124-FEDER-021150 - PTDC/SAU-889 ENB/119292/2010 and grant POCI-01-0145-FEDER-029516, co-financed by the ERDF/FEDER under the framework Competitiveness and Internationalization Operational Program (Programa Operacional Competitividade e Internacionalizacao -POCI), national funds through FCT/'Ministerio da Ciencia, Tecnologia e Ensino Superior' (FCT/MCTES) through the Portuguese State Budget. Grant PTDC/SAU-ENB/113696/2009 was attributed to R.P.N. R.D.M.T. and J.C. thank the support of FEDER funds through COMPETE and by national funds by FCT under the strategic project UID/FIS/04564/2016 and under POCI-01-0145-FEDER-031743 - PTDC/BIA-CEL/31743/2017. R.D.M.T. acknowledges FCT's support through the FCT Researcher Program.Biophysical cues influence many aspects of cell behavior. Stiffness of the extracellular matrix is probed by cells and transduced into biochemical signals through mechanotransduction protein networks, strongly influencing stem cell behavior. Cellular stemness is intimately related with mechanical properties of the cell, like intracellular contractility and stiffness, which in turn are influenced by the microenvironment. Pluripotency is associated with soft and low-contractility cells. Hence, we postulated that soft cell culture substrates, presumably inducing low cellular contractility and stiffness, increase the reprogramming efficiency of mesenchymal stem/stromal cells (MSCs) into induced pluripotent stem cells (iPSCs). We demonstrate that soft substrates (1.5 or 15 kPa polydimethylsiloxane – PDMS) caused modulation of several cellular features of MSCs into a phenotype closer to pluripotent stem cells (PSCs). MSCs cultured on soft substrates presented more relaxed nuclei, lower maturation of focal adhesions and F-actin assembling, more euchromatic and less heterochromatic nuclear DNA regions, and increased expression of pluripotency-related genes. These changes correlate with the reprogramming of MSCs, with a positive impact on the kinetics, robustness of colony formation and reprogramming efficiency. Additionally, substrate stiffness influences several phenotypic features of iPS cells and colonies, and data indicates that soft substrates favor full iPSC reprogramming.publishersversionpublishe

Screening for colorectal cancer leading into a new decade: the “Roaring ‘20s” for epigenetic biomarkers?

Colorectal cancer (CRC) has an important bearing (top five) on cancer incidence and mortality in the world. The etiology of sporadic CRC is related to the accumulation of genetic and epigenetic alterations that result in the appearance of cancer hallmarks such as abnormal proliferation, evasion of immune destruction, resistance to apoptosis, replicative immortality, and others, contributing to cancer promotion, invasion, and metastasis. It is estimated that, each year, at least four million people are diagnosed with CRC in the world. Depending on CRC staging at diagnosis, many of these patients die, as CRC is in the top four causes of cancer death in the world. New and improved screening tests for CRC are needed to detect the disease at an early stage and adopt patient management strategies to decrease the death toll. The three pillars of CRC screening are endoscopy, radiological imaging, and molecular assays. Endoscopic procedures comprise traditional colonoscopy, and more recently, capsule-based endoscopy. The main imaging modality remains Computed Tomography (CT) of the colon. Molecular approaches continue to grow in the diversity of biomarkers and the sophistication of the technologies deployed to detect them. What started with simple fecal occult blood tests has expanded to an armamentarium, including mutation detection and identification of aberrant epigenetic signatures known to be oncogenic. Biomarker-based screening methods have critical advantages and are likely to eclipse the classical modalities of imaging and endoscopy in the future. For example, imaging methods are costly and require highly specialized medical personnel. In the case of endoscopy, their invasiveness limits compliance from large swaths of the population, especially those with average CRC risk. Beyond mere discomfort and fear, there are legitimate iatrogenic concerns associated with endoscopy. The risks of perforation and infection make endoscopy best suited for a confirmatory role in cases where there are positive results from other diagnostic tests. Biomarker-based screening methods are largely non-invasive and are growing in scope. Epigenetic biomarkers, in particular, can be detected in feces and blood, are less invasive to the average-risk patient, detect early-stage CRC, and have a demonstrably superior patient follow-up. Given the heterogeneity of CRC as it evolves, optimal screening may require a battery of blood and stool tests, where each can leverage different pathways perturbed during carcinogenesis. What follows is a comprehensive, systematic review of the literature pertaining to the screening and diagnostic protocols used in CRC. Relevant articles were retrieved from the PubMed database using keywords including: “Screening”, “Diagnosis”, and “Biomarkers for CRC”. American and European clinical trials in progress were included as well.info:eu-repo/semantics/publishedVersio

Cofilin-1 is a mechanosensitive regulator of transcription

The mechanical properties of the extracellular environment are interrogated by cells and integrated through mechanotransduction. Many cellular processes depend on actomyosin-dependent contractility, which is influenced by the microenvironment's stiffness. Here, we explored the influence of substrate stiffness on the proteome of proliferating undifferentiated human umbilical cord-matrix mesenchymal stem/stromal cells. The relative abundance of several proteins changed significantly by expanding cells on soft (∼3 kPa) or stiff substrates (GPa). Many such proteins are associated with the regulation of the actin cytoskeleton, a major player of mechanotransduction and cell physiology in response to mechanical cues. Specifically, Cofilin-1 levels were elevated in cells cultured on soft comparing with stiff substrates. Furthermore, Cofilin-1 was de-phosphorylated (active) and present in the nuclei of cells kept on soft substrates, in contrast with phosphorylated (inactive) and widespread distribution in cells on stiff. Soft substrates promoted Cofilin-1-dependent increased RNA transcription and faster RNA polymerase II-mediated transcription elongation. Cofilin-1 is part of a novel mechanism linking mechanotransduction and transcription.publishe

Association between active genes occurs at nuclear speckles and is modulated by chromatin environment

Genes on different chromosomes can be spatially associated in the nucleus in several transcriptional and regulatory situations; however, the functional significance of such associations remains unclear. Using human erythropoiesis as a model, we show that five cotranscribed genes, which are found on four different chromosomes, associate with each other at significant but variable frequencies. Those genes most frequently in association lie in decondensed stretches of chromatin. By replacing the mouse α-globin gene cluster in situ with its human counterpart, we demonstrate a direct effect of the regional chromatin environment on the frequency of association, whereas nascent transcription from the human α-globin gene appears unaffected. We see no evidence that cotranscribed erythroid genes associate at shared transcription foci, but we do see stochastic clustering of active genes around common nuclear SC35-enriched speckles (hence the apparent nonrandom association between genes). Thus, association between active genes may result from their location on decondensed chromatin that enables clustering around common nuclear speckles

Effect of Cr(V) on reproductive organ morphology and sperm parameters: An experimental study in mice

BACKGROUND: Cr(V) species are formed during the intracellular reduction of Cr(VI), a ubiquitous environmental pollutant. In this study, the acute toxicity of a physiologically stable Cr(V) compound, [Cr(V)-BT](2- )(BT = bis(hydroxyethyl)aminotris(hydroxymethyl)methane) was investigated in the male reproductive system of sexually mature 60-day-old male ICR-CD1 mice. METHODS: Eight-week-old animals were subcutaneously injected daily with a dose of ca 8 μmol of Cr/mouse, during 5 days. The control group was injected with 0.5 mL of BT buffer. Testis and epididymis morphology was evaluated using light and transmission electron microscopy. Epididymal sperm counts, motility and acrosome integrity were also assayed using standard methods. RESULTS: Seminiferous epithelium abnormalities were detected in the Cr(V)-BT experimental group, including intraepithelial vacuolation, and remarkable degeneration of Sertoli cells, spermatocytes and spermatids. The premature release of germ cells into the tubular lumen was also evident. Histological evaluation of epididymal compartments revealed apparently normal features. However, the epididymal epithelium presented vacuolation. [Cr(V)-BT](2- )induced a reduction in sperm acrosome integrity. However, sperm motility and density were not significantly affected. CONCLUSION: This in vivo study using a Cr(V) compound, provides evidence for the potential reproductive hazards caused on male reproductive system by species containing chromium in intermediate oxidation states

MicroRNA-210 Regulates Mitochondrial Free Radical Response to Hypoxia and Krebs Cycle in Cancer Cells by Targeting Iron Sulfur Cluster Protein ISCU

BACKGROUND: Hypoxia in cancers results in the upregulation of hypoxia inducible factor 1 (HIF-1) and a microRNA, hsa-miR-210 (miR-210) which is associated with a poor prognosis. METHODS AND FINDINGS: In human cancer cell lines and tumours, we found that miR-210 targets the mitochondrial iron sulfur scaffold protein ISCU, required for assembly of iron-sulfur clusters, cofactors for key enzymes involved in the Krebs cycle, electron transport, and iron metabolism. Down regulation of ISCU was the major cause of induction of reactive oxygen species (ROS) in hypoxia. ISCU suppression reduced mitochondrial complex 1 activity and aconitase activity, caused a shift to glycolysis in normoxia and enhanced cell survival. Cancers with low ISCU had a worse prognosis. CONCLUSIONS: Induction of these major hallmarks of cancer show that a single microRNA, miR-210, mediates a new mechanism of adaptation to hypoxia, by regulating mitochondrial function via iron-sulfur cluster metabolism and free radical generation

Desemprego e ideologia: as explicações das causas do desemprego utilizadas por trabalhadores metalúrgicos

O objetivo deste estudo foi descrever e analisar os aspectos ideológicos das explicações sobre as causas do desemprego utilizadas por trabalhadores metalúrgicos. Consistiu na investigação qualitativo-compreensiva dos discursos de 12 metalúrgicos, 6 empregados e 6 desempregados, obtidos através de entrevistas semi-estruturadas e confrontativas. O desemprego é percebido pela maioria dos metalúrgicos como um fenômeno real, atual, crescente, grave e que atinge grande parte das regiões do Brasil. As explicações mais significativas e freqüentes foram agrupadas nas seguintes categorias: Governo, Falta de Qualificação, Características pessoais, Idade e Automatização. Constatou-se nos discursos um jogo de forças entre os fatores pessoais (ex: pessoas preferirem roubar, mascatear, “partir para as drogas” a trabalharem ou serem muito exigentes na escolha do emprego) e os fatores macrossociais (como automatização, políticas governamentais, globalização), não sendo possível identificar uma homogeneização dos discursos. Por existir conflito, há também a possibilidade de uma ação crítica por parte dos trabalhadores para reivindicar e buscar soluções para a atual e aguda situação do desemprego

α-MSH regulates intergenic splicing of MC1R and TUBB3 in human melanocytes

Alternative splicing enables higher eukaryotes to increase their repertoire of proteins derived from a restricted number of genes. However, the possibility that functional diversity may also be augmented by splicing between adjacent genes has been largely neglected. Here, we show that the human melanocortin 1 receptor (MC1R) gene, a critical component of the facultative skin pigmentation system, has a highly complex and inefficient poly(A) site which is instrumental in allowing intergenic splicing between this locus and its immediate downstream neighbour tubulin-β-III (TUBB3). These transcripts, which produce two distinct protein isoforms localizing to the plasma membrane and the endoplasmic reticulum, seem to be restricted to humans as no detectable chimeric mRNA could be found in MC1R expressing mouse melanocytes. Significantly, treatment with the MC1R agonist α-MSH or activation of the stress response kinase p38-MAPK, both key molecules associated with ultraviolet radiation dermal insult and subsequent skin tanning, result in a shift in expression from MC1R in favour of chimeric MC1R-TUBB3 isoforms in cultured melanocytes. We propose that these chimeric proteins serve to equip melanocytes with novel cellular phenotypes required as part of the pigmentation response

Mitochondrial Variability as a Source of Extrinsic Cellular Noise

We present a study investigating the role of mitochondrial variability in generating noise in eukaryotic cells. Noise in cellular physiology plays an important role in many fundamental cellular processes, including transcription, translation, stem cell differentiation and response to medication, but the specific random influences that affect these processes have yet to be clearly elucidated. Here we present a mechanism by which variability in mitochondrial volume and functionality, along with cell cycle dynamics, is linked to variability in transcription rate and hence has a profound effect on downstream cellular processes. Our model mechanism is supported by an appreciable volume of recent experimental evidence, and we present the results of several new experiments with which our model is also consistent. We find that noise due to mitochondrial variability can sometimes dominate over other extrinsic noise sources (such as cell cycle asynchronicity) and can significantly affect large-scale observable properties such as cell cycle length and gene expression levels. We also explore two recent regulatory network-based models for stem cell differentiation, and find that extrinsic noise in transcription rate causes appreciable variability in the behaviour of these model systems. These results suggest that mitochondrial and transcriptional variability may be an important mechanism influencing a large variety of cellular processes and properties