Oliveira, M. — Page 2 | Search bioRxiv

bioRxiv2021

Muscle-secreted neurturin couples myofiber oxidative metabolism and slow motor neuron identity.

Endurance exercise promotes skeletal muscle vascularization, oxidative metabolism, fiber-type switching, and neuromuscular junction integrity. Importantly, the metabolic and contractile properties of the muscle fiber must be coupled to the identity of the innervating motor neuron (MN). Here, we show that muscle-derived neurturin (NRTN) acts on muscle fibers and MNs to couple their characteristics. Using a muscle-specific NRTN transgenic mouse (HSA-NRTN) and RNA-sequencing of MN somas, we observed that retrograde NRTN signaling promotes a shift towards a slow MN identity. In muscle, NRTN increased capillary density, oxidative capacity, and induced a transcriptional reprograming favoring fatty acid metabolism over glycolysis. This combination of effects on muscle and MNs, makes HSA-NRTN mice lean with remarkable exercise performance and motor coordination. Interestingly, HSA-NRTN mice largely recapitulate the phenotype of mice with muscle-specific expression of its upstream regulator PGC-11. This work identifies NRTN as a myokine that couples muscle oxidative capacity to slow MN identity. HIGHLIGHTSO_LINRTN is a myokine induced by physical exercise. C_LIO_LIMuscle-derived NRTN promotes a slow motor neuron identity. C_LIO_LIMuscle-derived NRTN enhances muscle oxidative metabolism. C_LIO_LINRTN improves systemic metabolism, exercise performance and motor coordination. C_LI

physiology↗

bioRxiv2020

Loss of erythroblasts in acute myeloid leukemia causes iron redistribution with clinical implications

Acute myeloid leukemia (AML) is a heterogeneous disease with poor prognosis and limited treatment strategies. Determining the role of cell-extrinsic regulators of leukemic cells is vital to gain clinical insights into the biology of AML. Iron is a key extrinsic regulator of cancer but its systemic regulation remains poorly explored in AML. To address this question, we studied iron metabolism in AML patients at diagnosis and mechanisms involved using the syngeneic MLL-AF9-induced AML mouse model. We found that AML is a disorder with a unique iron profile not associated with inflammation or transfusion and characterized by high ferritin, low transferrin, high transferrin saturation (TSAT), and high hepcidin. The increased TSAT in particular, contrasts with observations in other cancer types and in anemia of inflammation. Using the MLL-AF9 mouse model of AML, we demonstrated that leukemic blasts take up iron and that the AML-induced loss of erythroblasts is responsible for iron redistribution and an increase in TSAT. We also show that elevated TSAT at diagnosis is independently associated with increased overall survival in AML and suggest that TSAT may be a relevant prognostic marker in AML.

cancer biology↗

bioRxiv2020

Chicken cGAS senses fowlpox virus infection and regulates macrophage effector function

The anti-viral immune response is dependent on the ability of infected cells to sense foreign nucleic acids. In multiple species, the pattern recognition receptor (PRR) cyclic GMP-AMP synthase (cGAS) senses viral DNA as an essential component of the innate response. cGAS initiates a range of signalling outputs that are dependent on generation of the second messenger cGAMP that binds to the adaptor protein stimulator of interferon genes (STING). Here we show that in chicken macrophages, the cGAS/STING pathway is essential not only for the production of type-I interferons in response to intracellular DNA stimulation, but also for regulation of macrophage effector functions including the expression of MHC-II and co-stimulatory molecules. In the context of fowlpox, an avian DNA virus infection, the cGAS/STING pathway was found to be responsible for type-I interferon production and MHC-II transcription. The sensing of fowlpox virus DNA is therefore essential for mounting an anti-viral response in chicken cells and for regulation of a specific set of macrophage effector functions.

immunology↗

bioRxiv2020

Taxonomic classification of strain PO100/5 shows a broader geographic distribution and genetic markers of the recently described Corynebacterium silvaticum

The bacterial strain PO100/5 was isolated from a skin abscess of a pig (Sus scrofa domesticus) in the Alentejo region of southern Portugal. It was identified as Corynebacterium pseudotuberculosis using biochemical tests, multiplex PCR and Pulsed Field Gel Electrophoresis. After genome sequencing and rpoB phylogeny, the strain was classified as C. ulcerans. To better understand the taxonomy of this strain and improve identification methods, we compared strain PO100/5 to other publicly available genomes from the C. diphtheriae group. Taxonomic analysis reclassified it and three others strains as belonging to the recently described C. silvaticum, which have been isolated from wild boar and roe deer in Germany and Austria. The results showed that PO100/5 is the first sequenced genome of a C. silvaticum strain from a domestic animal and a different geographical region, is a putative producer of the diphtheriae toxin, and has a unique sequence type. Genomic analysis of PO100/5 showed four prophages and eight conserved genomic islands when compared to C. ulcerans. Pangenome analysis of 38 C. silvaticum and 76 C. ulcerans samples suggest that C. silvaticum is a clonal species, with 73.6% of conserved genes and a pangenome near to being closed ( > 0.952). 172 conserved genes are unique to C. silvaticum when compared to C. ulcerans, with most related to nutrient uptake and metabolism, prophages or immune evasion. These unique genes could be used as genetic markers for species identification. This information can be useful for identification and surveillance of this pathogen, especially in regard to the possibility of zoonotic transmission.

genomics↗

bioRxiv2020

RADSex: a computational workflow to study sex determination using Restriction Site-Associated DNA Sequencing data

The study of sex determination and sex chromosome organisation in non-model species has long been technically challenging, but new sequencing methodologies are now enabling precise and high-throughput identification of sex-specific genomic sequences. In particular, Restriction Site-Associated DNA Sequencing (RAD-Seq) is being extensively applied to explore sex determination systems in many plant and animal species. However, software designed to specifically search for sex-biased markers using RAD-Seq data is lacking. Here, we present RADSex, a computational analysis workflow designed to study the genetic basis of sex determination using RAD-Seq data. RADSex is simple to use, requires few computational resources, makes no prior assumptions about type of sex-determination system or structure of the sex locus, and offers convenient visualization through a dedicated R package. To demonstrate the functionality of RADSex, we re-analyzed a published dataset of Japanese medaka, Oryzias latipes, where we uncovered a previously unknown Y chromosome polymorphism. We then used RADSex to analyze new RAD-Seq datasets from 15 fish species spanning multiple systematic orders. We identified the sex determination system and sex-specific markers in six of these species, five of which had no known sex-markers prior to this study. We show that RADSex greatly facilitates the study of sex determination systems in non-model species and outperforms the commonly used RAD-Seq analysis software STACKS. RADSex in speed, resource usage, ease of application, and visualization options. Furthermore, our analysis of new datasets from 15 species provides new insights on sex determination in fish.

bioinformatics↗

bioRxiv2020

Hsp27 reduces glycation-induced toxicity and aggregation of α-synuclein

-synuclein (aSyn) is a major player in Parkinsons disease (PD) and a group of other disorders collectively known as synucleinopathies, but the precise molecular mechanisms involved are still unclear. aSyn, as virtually all proteins, undergoes a series of posttranslational modifications (PTMs) during its lifetime which can affect its biology and pathobiology. We recently showed that glycation of aSyn by methylglyoxal (MGO) potentiates its oligomerization and toxicity, induces dopaminergic neuronal cell loss in mice, and affects motor performance in flies. Small heat-shock proteins (sHsps) are molecular chaperones that facilitate the folding of proteins or target misfolded proteins for clearance. Importantly, sHsps were shown to prevent aSyn aggregation and cytotoxicity. Upon treating cells with increasing amounts of methylglyoxal, we found that the levels of Hsp27 decreased in a dose-dependent manner. Therefore, we hypothesized that restoring the levels of Hsp27 in glycating environments could alleviate the pathogenicity of aSyn. Consistently, we found that Hsp27 reduced MGO-induced aSyn aggregation in cells, leading to the formation of non-toxic aSyn species. Remarkably, increasing the levels of Hsp27 suppressed the deleterious effects induced by MGO. Our findings suggest that in glycating environments, the levels of Hsp27 are important for modulating the glycation-associated cellular pathologies in synucleinopathies.

neuroscience↗

bioRxiv2020

Assessment of mitochondrial physiology of murine white adipose tissue by mechanical permeabilization and lipid depletion

White adipose tissue (WAT) is classically associated with energy storage in the form of triacylglycerol and is directly associated with metabolic disorders, including obesity. Mitochondria regulates cellular expenditure and are active in WAT. Although isolated mitochondria have been classically used to assess their functions, several artifacts can be introduced by this approach. Although methods to assess mitochondrial physiology in permeabilized WAT were proposed, important limitations that affect organelle function exist. Here, we established and validated a method for functional evaluation of mice mesenteric WAT (mWAT) mitochondria by using mechanical permeabilization in combination with lipid depletion and high-resolution respirometry. We observed that mild stirring of mWAT for 20 minutes at room temperature with 4% fatty acid-free albumin selectively permeabilized white adipocytes plasma membrane. In these conditions, mWAT mitochondria were intact and coupled, exhibiting succinate-induced respiratory rates that were sensitive to classical modulators of oxidative phosphorylation. Finally, the respiratory capacity of mWAT in females was significantly higher than in males, an observation that agrees with reported data using isolated mitochondria. The functional assessment of mWAT mitochondria through mild mechanical permeabilization, lipid depletion and high resolution respirometry proposed here will contribute to a better understanding of WAT biology in several pathophysiological contexts.

biochemistry↗

bioRxiv2019

An investigation of PS-b-PEO polymersomes for the oral treatment and diagnosis of hyperammonemia

Ammonia-scavenging transmembrane pH-gradient poly(styrene)-b-poly(ethylene oxide) polymersomes were investigated for the oral treatment and diagnosis of hyperammonemia, a condition associated with serious neurologic complications in patients with liver disease as well as in infants with urea cycle disorders. While these polymersomes were highly stable in simulated intestinal fluids at extreme bile salt and osmolality conditions, they unexpectedly did not reduce plasmatic ammonia levels in cirrhotic rats after oral dosing. Incubation in dietary fiber hydrogels mimicking the colonic environment suggested that the vesicles were probably destabilized during the dehydration of the intestinal chyme. Our findings question the relevance of commonly used simulated intestinal fluids for studying vesicular stability. With the encapsulation of a pH-sensitive dye in the polymersome core, the local pH increase upon ammonia influx could be exploited to assess the ammonia concentration in the plasma of healthy and cirrhotic rats as well as in other fluids. Due to its high sensitivity and selectivity, this novel polymersome-based assay could prove useful in the monitoring of hyperammonemic patients and in other applications such as drug screening tests.\n\nGraphical abstract\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=94 SRC=\"FIGDIR/small/631630v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (28K):\norg.highwire.dtl.DTLVardef@dd9b02org.highwire.dtl.DTLVardef@ebb129org.highwire.dtl.DTLVardef@1bc15e3org.highwire.dtl.DTLVardef@1411a28_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗

bioRxiv2019

Mitochondrial glycerol phosphate oxidation is modulated by adenylates through allosteric regulation of cytochrome c oxidase activity in mosquito flight muscle.

The huge energy demand posed by insect flight activity is met by an efficient oxidative phosphorylation process that takes place within flight muscle mitochondria. In the major arbovirus vector Aedes aegypti, mitochondrial oxidation of pyruvate, proline and glycerol 3 phosphate (G3P) represent the major energy sources of ATP to sustain flight muscle energy demand. Although adenylates exert critical regulatory effects on several mitochondrial enzyme activities, the potential consequences of altered adenylate levels to G3P oxidation remains to be determined. Here, we report that mitochondrial G3P oxidation is controlled by adenylates through allosteric regulation of cytochrome c oxidase (COX) activity in A. aegypti flight muscle. We observed that ADP significantly activated respiratory rates linked to G3P oxidation, in a protonmotive force-independent manner. Kinetic analyses revealed that ADP activates respiration through a slightly cooperative mechanism. Despite adenylates caused no effects on G3P-cytochrome c oxidoreductase activity, COX activity was allosterically activated by ADP. Conversely, ATP exerted powerful inhibitory effects on respiratory rates linked to G3P oxidation and on COX activity. We also observed that high energy phosphate recycling mechanisms did not contribute to the regulatory effects of adenylates on COX activity or G3P oxidation. We conclude that mitochondrial G3P oxidation by A. aegypti flight muscle is regulated by adenylates essentially through the allosteric modulation of COX activity, underscoring the bioenergetic relevance of this novel mechanism and the potential consequences for mosquito dispersal.

biochemistry↗

bioRxiv2019

Processing cookies formulated with goat cream enriched with conjugated linoleic acid

Goat fat is one of the most important sources of conjugated linoleic acid (CLA), a fatty acid which has health benefits. However, CLA consumption is limited to meats and milk products as CLA is generated in ruminants. This study aimed to replace vegetable fat by goat cream enriched with CLA. Four cookie recipes were developed with only the fat source being different: CVF - vegetable fat; CB - butter; CGC - goat cream without CLA; CGCLA - goat cream with CLA. Cookies were evaluated according to physical (color and texture) and physical-chemical parameters (lipids, proteins, total sugars, fiber, ash, moisture and Aw), Consumer Testing (n = 123) and lipid profile. The CGCLA presented higher values in the color parameters, and the higher and the lower scores in relation to hardness were 5.54 (CB) and 2.21 (CVF), respectively. Lipids and total sugars varied inversely, and the highest percentages of lipids were in the CVF and CG samples, which obtained lower total sugar content. There was no difference in the acceptance and preference of the four formulations, and the formulations with the goat creams (CG and CGCLA) were as accepted as CFV. The lipid profile of the cookies presented CFV with the highest percentage of trans fatty acids (TFA) with 16.76 %. CGCLA presented 70 % more CLA in relation to CB and CGC, thus certifying that CLA was present in relevant quantities in the CGCLA, even after cooking. The CGCLA is a biscuit with higher levels of CLA, and in this study it was possible to verify that the goat milk cream enriched with CLA can be used in producing cookies which adds functional and nutritional properties to them and offers other alternatives to produce food from goat's milk cream.

biochemistry↗

bioRxiv2018

Psychosocial stress and central adiposity: A Brazilian study with users of the public health system

ObjectiveTo assess the association between indicators of psychosocial stress and central adiposity in adult users of the Unified Health System (SUS) from Southeast of Brazil.\n\nMethodsThis cross-sectional study was conducted with 384 adults (20 to 59 years old) from the city of Alegre, Southeastern Brazil. The simple random sample represented the population using the public health system of the municipality. The prevalence of obesity was based on the Body Mass Index, and central adiposity (dependent variable) was measured by waist circumference in centimeters. The independent variables were the following indicators of psychosocial stress: food and nutrition insecurity (yes/no), serum cortisol (g/dL), symptoms suggestive of depression using the Beck Depression Inventory-II [≥] 17 (yes/no), and altered blood pressure [≥] 130/85 mmHg (yes/no). Univariate linear regression was performed between central adiposity and each stress indicator, and later the models were adjusted for socioeconomic, health, and lifestyle variables. All analyses were stratified by rural and urban location.\n\nResultsThe prevalence of weight excess was 68.3%, and 71.5% of individuals presented an increased risk for metabolic complications related to central adiposity. Mean waist circumference scores for the rural and urban population were 89.3 {+/-} 12.7 cm and 92.9 {+/-} 14.7 cm, respectively (p = 0.012). Indicators of stress that were associated with central adiposity were: cortisol in the rural population and altered blood pressure in the urban population. This occurred both in the raw analysis and in the models adjusted for confounding factors.\n\nConclusionThe associations between stress and adiposity were different between rural (cortisol - inverse association) and urban (altered blood pressure) lifestyles, confirming the influence of local and psychosocial subsistence on the modulation of stress and on how individuals react or restrain stressors. Stress reduction strategies can be useful in public health programs designed to prevent or treat obesity.

genetics↗

bioRxiv2018

Psychosocial stress and central adiposity: A Brazilian study with users of the public health system

ObjectiveTo assess the association between indicators of psychosocial stress and central adiposity in adult users of the Unified Health System (SUS) from Southeast of Brazil.\n\nMethodsThis cross-sectional study was conducted with 384 adults (20 to 59 years old) from the city of Alegre, Southeastern Brazil. The simple random sample represented the population using the public health system of the municipality. The prevalence of obesity was based on the Body Mass Index, and central adiposity (dependent variable) was measured by waist circumference in centimeters. The independent variables were the following indicators of psychosocial stress: food and nutrition insecurity (yes/no), serum cortisol (g/dL), symptoms suggestive of depression using the Beck Depression Inventory-II [≥] 17 (yes/no), and altered blood pressure [≥] 130/85 mmHg (yes/no). Univariate linear regression was performed between central adiposity and each stress indicator, and later the models were adjusted for socioeconomic, health, and lifestyle variables. All analyses were stratified by rural and urban location.\n\nResultsThe prevalence of weight excess was 68.3%, and 71.5% of individuals presented an increased risk for metabolic complications related to central adiposity. Mean waist circumference scores for the rural and urban population were 89.3 {+/-} 12.7 cm and 92.9 {+/-} 14.7 cm, respectively (p = 0.012). Indicators of stress that were associated with central adiposity were: cortisol in the rural population and altered blood pressure in the urban population. This occurred both in the raw analysis and in the models adjusted for confounding factors.\n\nConclusionThe associations between stress and adiposity were different between rural (cortisol - inverse association) and urban (altered blood pressure) lifestyles, confirming the influence of local and psychosocial subsistence on the modulation of stress and on how individuals react or restrain stressors. Stress reduction strategies can be useful in public health programs designed to prevent or treat obesity.

genetics↗