Epididymal mRNA expression profiles for the protein disulfide isomerase gene family: Modulation by development and androgens.

BACKGROUND: The endoplasmic reticulum (ER) is the central hub for protein quality control, where the protein disulfide isomerases (PDIs), encoded by at least 21 genes, play a pivotal role. These multifunctional proteins contribute to disulfide bond formation, proper folding, and protein modifications, and may act as hormone-binding proteins (e.g., steroids), influencing hormone biology. The interplay between ER proteostasis, PDIs, and epididymis-a crucial site for sperm maturation-remains largely understudied. OBJECTIVES: This study characterizes transcriptional signatures of Pdi genes in the epididymis. MATERIAL AND METHODS: Transcriptional profiles of selected Pdi genes were assessed in adult Wistar rat tissues, and epididymis under different experimental conditions (developmental stages, surgical castration, and efferent ductules ligation [EDL]). In silico bioinformatic analyses identified expression trends of this gene family in human epididymal segments. RESULTS: P4hb, Pdia3, Pdia5, Pdia6, Erp44, Erp29, and Casq1 transcripts were detected in both reproductive and non-reproductive tissues, while Casq2 exhibited higher abundance in vas deferens, prostate, and heart. Pdilt, highly expressed in testis, and Pdia2, highly expressed in heart, showed minimal mRNA levels in the epididymis. In the mesonephric duct, epididymal embryonic precursor, P4hb, Pdia3, Pdia5, Pdia6, and Erp29 mRNAs were found at gestational day (GD) 17.5. Except for Erp29, which remained stable, these Pdi transcript levels increased from GD17.5 to GD20.5, when epididymal morphogenesis occurs, and were maintained to varying degrees in the epididymis during postnatal development. Surgical castration downregulated P4hb, Pdia3, Pdia5, Pdia6, Pdilt and Erp29 transcripts, an effect reversed by testosterone replacement. Conversely, transcript levels remained unaffected by EDL, except P4hb, which was reduced in caput epididymis. All 21 PDI genes exhibited diverse transcriptional profiles across the human epididymis. DISCUSSION AND CONCLUSION: The findings lay the foundations to explore Pdi genes in epididymal biology. As a considerable proportion of male infertility cases are idiopathic, targeting hormonal regulation of protein quality control in epididymis represents a route to address male infertility and advance therapeutic interventions in this domain.

Apparent metabolizable energy and ileal amino acid digestibility of commercial soybean meals of different origins in broilers.

We studied the chemical composition and the in vivo AMEn content and apparent (AID) and standardized (SID) ileal digestibility of CP and amino acids (AA) of 27 samples of soybean meals (SBM) from Argentina (ARG), Brazil (BRA), and USA, collected in Spain. On 88% DM basis, the BRA meals had more CP (46.9 vs. 46.0 and 45.9%; P < 0.05) and less sucrose (5.21 vs. 6.28 and 6.47%; P < 0.001) and stachyose (4.20 vs. 4.66 and 4.78%; P < 0.05) than the USA and ARG meals. Urease activity, protein dispersibility index, KOH protein solubility, and trypsin inhibitor activity values, were higher for the USA meals than for the South American meals (P < 0.05). In the in vivo trial, broilers received a common crumble diet from 0 to 16 d of age and then, their respective experimental diets (53% of a N-free diet and 47% of each of the 27 SBM tested) in mash form, for 5 d. The AMEn (2,334 vs. 2,282 and 2,277 kcal/kg; P = 0.062) and the AID (87.3 vs. 86.7 and 86.4%; P = 0.054) and SID (91.9 vs. 91.2 and 90.8%; P < 0.05) of the protein, were greater for the USA meals than for the ARG and BRA meals. In fact, the SID of Lys (93.5 vs. 93.0 and 92.1%; P < 0.001) and of the sum of Lys, Met, Thr, Trp, and Cys (91.4 vs. 91.0 and 90.2%; P < 0.05) were greater for the USA meals than for the ARG and BRA meals. In summary, the chemical composition, protein quality indicators, AMEn content, and ileal digestibility of the CP and the AA of the SBM, varied with the country of origin of the soybeans. In order to increase the accuracy of the feed formulation process, the composition and nutrient content of commercial batches of SBM, by country of origin should be controlled and periodically updated.

Determination of Indispensable Amino Acid Digestibility of the Red Kidney Bean in Humans Using a Dual Stable Isotope Tracer Method.

BACKGROUND: Protein quality of the red kidney bean (RKB), a common source of dietary protein, has been assessed using the protein digestibility-corrected amino acid score (PDCAAS) determined in animal models using mainly oro-fecal digestibility. More recently, the FAO recommended to use digestible indispensable amino acid score (DIAAS) instead of PDCAAS but highlighted insufficient data on true ileal indispensable amino acid (IAA) digestibility of proteins because amino acids are absorbed in the ileum. OBJECTIVES: Using a recently developed dual stable isotope tracer method, we aimed to measure each IAA digestibility as representation of true ileal digestibility of the RKB, Phaseolus vulgaris, in humans consuming a typical Jamaican meal. METHODS: RKB-IAAs were intrinsically labeled by adding 2H2O to the plants. Uniformly labeled-[13C]-spirulina (standard protein) was added to a meal prepared with the labeled RKB and fed to 10 healthy adults (5 males, 5 females) in a nonrandomized trial as primed/intermittent doses to achieve a steady state IAA enrichment in plasma. Enrichment of 2H- and 13C-labeled IAA in plasma and the bean was measured by mass spectrometry. Each IAA digestibility (except tryptophan and histidine) was calculated as the ratio of plasma 2H-IAA to meal 2H-IAA divided by the ratio of plasma 13C-IAA to meal 13C-IAA adjusted for loss of 2H-atom during transamination and digestibility of spirulina. RESULTS: Adequate IAA labeling (>1000 ppm 2H excess) and plasma plateau isotopic enrichment were achieved. Mean RKB-IAA digestibility (%) was 79.4 ± 0.5, ranging from 69.0 ± 1.2 (threonine) to 85.7 ± 1.7 (lysine). CONCLUSION: The dual stable isotope tracer digestibility data are similar to published oro-fecal digestibility supporting substantial nitrogen exchange in the colon. The individual IAA digestibility is useful to derive DIAAS to replace PDCAAS. Using published RKB-IAA composition, extrapolated DIAAS was 0.63 based on the lowest score for methionine. CLINICAL TRIAL REGISTRATION: https://register. CLINICALTRIALS: gov; ID: NCT-04118517.

Composition and Flowering Quality of Cacahuacintle Maize Populations from the High Valleys of Mexico.

Cacahuacintle is one of the maize types with great demand for pozole preparation; however, little is known about the variation in chemical composition and flowered grain quality among populations. Physicochemical characteristics, flowered grain quality, pasting properties, and starch microstructure were evaluated in 33 populations of Cacahuacintle maize collected in Valles Altos, Mexico. The seeds samples of corn were obtained in 2017 from local farmers in the states of Mexico, Puebla, and Tlaxcala. Results were analyzed under a completely randomized design, and the ANOVA, Tukey test, and principal components were obtained. The ANOVA showed significance (p ≤ 0.05) in 18 of the 22 variables evaluated. The TE-6, AM-7, and CA-6 populations were outstanding for the good quality of their protein, pasting viscosity, and flowered grain quality. Nine populations collected in Calimaya, estate of Mexico, and Serdan Valley, state of Puebla, presented excellent physical, pasting, and flowery grain characteristics, with reduced protein content and lysine and tryptophan values typical of maize with normal endosperm. The softness of the endosperm grain, starch microstructural, and pasting characteristics of Cacahuacintle maize populations have a fundamental role in reducing the time and increasing the flowered grain volume, properties that were different from those observed in the Chalqueño, included as dent maize check. Variations in grain quality among Cacahuacintle maize populations is an important genetic resource for the improvement of the nutritional and flowering quality of Cacahuacintle maize.

Optimization of detergents in solubilization and reconstitution of Aquaporin Z: A structural approach.

BACKGROUND: The exceptional capacities of aquaporins in terms of water permeation and selectivity have made them an interesting system for membrane applications. Despite the multiple attempts for immobilizing the aquaporins over a porous substrate, there is a lack of studies related to the purification and reconstitution steps, principally associated with the use of detergents in solubilization and destabilization steps. This study analyzed the effect of detergents in Aquaporin Z solubilization, considering the purity and structural homogeneity of the protein. METHODS: The extraction process was optimized by the addition of detergent at the sonication step, which enabled the omission of the ultracentrifugation and resuspension steps. Two detergents, Triton X-100, and octyl-glucoside were also evaluated. Destabilization mediated by detergents was used as reconstitution method. Saturation and solubilization points were defined by detergent concentration and both, liposomes and proteoliposomes, were analyzed by size distribution and permeability assays. Detergent removal with Bio-beads was also analyzed. RESULTS: Octyl glucoside ensures structural stability and homogeneity of Aquaporin Z. However, high concentrations of detergents induce the presence of defects in proteoliposomes. While saturated liposomes create homogeneous and functional structures, solubilized liposomes get affected by a reassembly process, creating vesicle defects with anomalous permeability profiles. CONCLUSIONS: Detergent concentration affects the structural conformation of proteoliposomes in the reconstitution process. GENERAL SIGNIFICANCE: Since the destabilization process is dependent on vesicle, detergent, and buffer composition, optimization of this process should be mandatory for further studies. All these considerations will allow achieving the potential of Aquaporins and any other integral membrane protein in their applications for industrial purposes.

The potential of cold-shock promoters for the expression of recombinant proteins in microbes and mammalian cells.

BACKGROUND: Low-temperature expression of recombinant proteins may be advantageous to support their proper folding and preserve bioactivity. The generation of expression vectors regulated under cold conditions can improve the expression of some target proteins that are difficult to express in different expression systems. The cspA encodes the major cold-shock protein from Escherichia coli (CspA). The promoter of cspA has been widely used to develop cold shock-inducible expression platforms in E. coli. Moreover, it is often necessary to employ expression systems other than bacteria, particularly when recombinant proteins require complex post-translational modifications. Currently, there are no commercial platforms available for expressing target genes by cold shock in eukaryotic cells. Consequently, genetic elements that respond to cold shock offer the possibility of developing novel cold-inducible expression platforms, particularly suitable for yeasts, and mammalian cells. CONCLUSIONS: This review covers the importance of the cellular response to low temperatures and the prospective use of cold-sensitive promoters to direct the expression of recombinant proteins. This concept may contribute to renewing interest in applying white technologies to produce recombinant proteins that are difficult to express.

Cowpea: A low-cost quality protein source for food safety in marginal areas for agriculture.

Cowpea is a low-cost protein source for human nutrition for the world's impoverished regions. Therefore, the yield and total grain protein content (TGPC) of two modern commercials genotypes, Novaera and Gurguéia, and two traditional local genotypes, Paulistinha and EPACE-10, were studied. Also, leaf area and dry weight, leaf soluble protein content, and chlorophyll a fluorescence, parameters related to photosynthetic capacity, were used to evaluate genotypes. Under optimal conditions, the yield of EPACE-10 and Paulistinha, with higher TGPC, was lower than for Gurguéia and Novaera, which showed lower TGPC. The four cowpea genotypes showed high lysine content and low methionine and cysteine. The results revealed a negative correlation between yield and TGPC. The modern commercial genotype Novaera showed a high yield with low TGPC but a higher globulin and albumin content than Gurguéia. Thus, it can be used in high-input agriculture. In contrast, the traditional local genotype EPACE-10, with high TGPC and higher amino acid content than Paulistinha, is indicated for low-input agriculture in marginal areas for food safety under climate changes.

Effects of the substitution of wheat flour with raw or germinated ayocote bean (Phaseolus coccineus) flour on the nutritional properties and quality of bread.

This study aimed to evaluate the potential of 10%, 20%, and 30% of raw (ARF) and germinated (AGF) ayocote bean flour as a partial substitute for wheat flour in breadmaking. Substitution with both ayocote bean flours modified the water absorption and development time while maintaining the dough stability. Supplemented breads had 13%, 51%, and 132% higher protein, mineral, and crude fiber content, respectively, than control bread (100% wheat). The breadmaking features, color and crumb firmness, were affected by the substitution level. Sensory analysis revealed that germination could improve the taste and smell of breads produced with ayocote bean flour. The sensory attribute scores of 10% AGF bread were comparable to those of the control bread. Supplementation reduced the in vitro protein digestibility, although the effect was less pronounced in 10% ARF and 20% AGF breads. The limiting amino acid score of supplemented breads increased up to 70%, which improved their protein digestibility-corrected amino acid scores. Supplementation with 20% or 30% of both ARF and AGF increased resistant starch values and decreased the total digestible starch of breads. Thus, the results showed that substituting wheat with ARF or AGF improves the nutritional properties of bread. However, low substitution levels should be selected to avoid a considerable decrease in physical and sensory properties. PRACTICAL APPLICATION: Substituting wheat flour with ayocote bean flour improved the nutritional value of bread. Germination of ayocote beans decreased the cooking stability of composite dough. Bread fortified with ayocote flour had high levels of essential amino acids. Bread with raw or germinated ayocote flours had high limiting amino acid scores. Composite bread had high resistant starch and low total digestible starch.

Whey Protein Supplementation Is Superior to Leucine-Matched Collagen Peptides to Increase Muscle Thickness During a 10-Week Resistance Training Program in Untrained Young Adults.

The purpose of this study was to investigate the effects of supplementation of whey protein (WP) versus leucine-matched collagen peptides (CP) on muscle thickness MT and performance after a resistance training (RT) program in young adults. Twenty-two healthy untrained participants were randomly assigned to either a WP (n = 11) or leucine-matched CP (n = 11) group and then submitted to a supervised 10-week RT program (3 days/week). The groups were supplemented with an equivalent amount of WP (35 g, containing 3.0 g of leucine) and CP (35 g, containing 1.0 g of leucine and 2.0 g of free leucine) during the intervention period (after each workout and in the evening on nontraining days). MT of the vastus lateralis and biceps brachii, isokinetic peak torque and mean power output of the elbow flexors, and peak power output of the lower body were assessed before and after the RT program. The WP group experienced a greater (interaction, p < .05) increase in the vastus lateralis (effect size, WP = 0.68 vs. CP = 0.38; % Δ, WP = 8.4 ± 2.5 vs. CP = 5.6 ± 2.6%) and biceps brachii muscle thickness (effect size, WP = 0.61 vs. CP = 0.35; % , WP = 10.1 ± 3.8 vs. CP = 6.0 ± 3.2%), with a similar increase in muscle performance (peak torque, mean power output, and peak power output) between groups (time p < .05). Supplementation with WP was superior to leucine content-matched CP supplementation in increasing muscle size, but not strength and power, after a 10-week RT program in young adults.

Protein Quality in Infant Formulas Marketed in Brazil: Assessments on Biodigestibility, Essential Amino Acid Content and Proteins of Biological Importance.

Infant formulas, designed to provide similar nutritional composition and performance to human milk, are recommended when breastfeeding is not enough to provide for the nutritional needs of children under 12 months of age. In this context, the present study aimed to assess the protein quality and essential amino acid content of both starting (phase 1) and follow-up (phase 2) formulas from different manufacturers. The chemical amino acid score and protein digestibility corrected by the amino acid score were calculated. The determined protein contents in most formulas were above the maximum limit recommended by FAO and WHO guidelines and at odds with the protein contents declared in the label. All infant formulas contained lactoferrin (0.06 to 0.44 g·100 g-1) and α-lactalbumin (0.02 to 1.34 g·100 g-1) below recommended concentrations, whereas ĸ-casein (8.28 to 12.91 g·100 g-1), α-casein (0.70 to 2.28 g·100 g-1) and ß-lactoglobulin (1.32 to 4.19 g·100 g-1) were detected above recommended concentrations. Essential amino acid quantification indicated that threonine, leucine and phenylalanine were the most abundant amino acids found in the investigated infant formulas. In conclusion, infant formulas are still unconforming to nutritional breast milk quality and must be improved in order to follow current global health authority guidelines.

DegP protease is essential for tolerance to salt stress in the plant growth-promoting bacterium Gluconacetobacter diazotrophicus PAL5.

The use of plant growth-promoting bacteria represents an alternative to the massive use of mineral fertilizers in agriculture. However, some abiotic stresses commonly found in the environment, like salinity, can affect the efficiency of this approach. Here, we investigated the key mechanisms involved in the response of the plant growth-promoting bacterium Gluconacetobacter diazotrophicus to salt stress by using morphological and cell viability analyses, comparative proteomics, and reverse genetics. Our results revealed that the bacteria produce filamentous cells in response to salt at 100 mM and 150 mM NaCl. However, such a response was not observed at higher concentrations, where cell viability was severely affected. Proteomic analysis showed that salt stress modulates proteins involved in several pathways, including iron uptake, outer membrane efflux, osmotic adjustment, cell division and elongation, and protein transport and quality control. Proteomic data also revealed the repression of several extracytoplasmic proteins, especially those located at periplasm and outer membrane. The role of such pathways in the tolerance to salt stress was analyzed by the use of mutant defectives for Δtbdr (iron uptake), ΔmtlK and ΔotsA (compatible solutes synthesis), and ΔdegP (quality control of nascent extracytoplasmic proteins). ΔdegP presented the highest sensitivity to salt stress, Δtbdr, andΔmtlK also showed increased sensitivity, but ΔotsA was not affected. This is the first demonstration that DegP protein, a protease with minor chaperone activity, is essential for tolerance to salt stress in G. diazotrophicus. Our data contribute to a better understanding of the molecular bases that control the bacterial response/tolerance to salt stress, shedding light on quality control of nascent extracytoplasmic proteins.

Influence of nascent polypeptide positive charges on translation dynamics.

Protein segments with a high concentration of positively charged amino acid residues are often used in reporter constructs designed to activate ribosomal mRNA/protein decay pathways, such as those involving nonstop mRNA decay (NSD), no-go mRNA decay (NGD) and the ribosome quality control (RQC) complex. It has been proposed that the electrostatic interaction of the positively charged nascent peptide with the negatively charged ribosomal exit tunnel leads to translation arrest. When stalled long enough, the translation process is terminated with the degradation of the transcript and an incomplete protein. Although early experiments made a strong argument for this mechanism, other features associated with positively charged reporters, such as codon bias and mRNA and protein structure, have emerged as potent inducers of ribosome stalling. We carefully reviewed the published data on the protein and mRNA expression of artificial constructs with diverse compositions as assessed in different organisms. We concluded that, although polybasic sequences generally lead to lower translation efficiency, it appears that an aggravating factor, such as a nonoptimal codon composition, is necessary to cause translation termination events.

ß2 -adrenoceptor activation improves skeletal muscle autophagy in neurogenic myopathy.

ß2 -adrenoceptor agonists improve autophagy and re-establish proteostasis in cardiac cells; therefore, suggesting autophagy as a downstream effector of ß2 -adrenoceptor signaling pathway. Here, we used the pharmacological and genetic tools to determine the autophagy effect of sustained ß2 -adrenoceptor activation in rodents with neurogenic myopathy, which display impaired skeletal muscle autophagic flux. Sustained ß2 -adrenoceptor activation using Formoterol (10 µg kg-1  day-1 ), starting at the onset of neurogenic myopathy, prevents disruption of autophagic flux in skeletal muscle 14 days after sciatic nerve constriction. These changes are followed by reduction of the cytotoxic protein levels and increased skeletal muscle cross-sectional area and contractility properties. Of interest, sustained administration of Formoterol at lower concentration (1 µg kg-1  day-1 ) induces similar improvements in skeletal muscle autophagic flux and contractility properties in neurogenic myopathy, without affecting the cross-sectional area. Sustained pharmacological inhibition of autophagy using Chloroquine (50 mg kg-1  day-1 ) abolishes the beneficial effects of ß2 -adrenoceptor activation on the skeletal muscle proteostasis and contractility properties in neurogenic myopathy. Further supporting an autophagy mechanism for ß2 -adrenoceptor activation, skeletal muscle-specific deletion of ATG7 blunts the beneficial effects of ß2 -adrenoceptor on skeletal muscle proteostasis and contractility properties in neurogenic myopathy in mice. These findings suggest autophagy as a critical downstream effector of ß2 -adrenoceptor signaling pathway in skeletal muscle.

Food processing for the improvement of plant proteins digestibility.

Proteins are essential macronutrients for the human diet. They are the primary source of nitrogen and are fundamental for body structure and functions. The plant protein quality (PPQ) refers to the bioavailability, digestibility, and amino acid composition. The digestibility specifies the protein quantity absorbed by an organism relative to the consumed amount and depends on the protein structure, previous processing, and the presence of compounds limiting the digestion. The latter are so-called antinutritional factors (ANF), exemplified by phytates, tannins, trypsin inhibitors, and lectins. Animal proteins are known to have better digestibility than plant proteins due to the presence of ANF in plants. Thus, the inactivation of ANF throughout food processing may increase the PPQ. New food processing, aiming to increase the digestibility of plant proteins, and new sources of proteins are being studied for the animal protein substitution. Here, it is presented the impact of processing on the protein digestibility and reduction of ANF. Several techniques, such as cooking, autoclaving, germination, microwave, irradiation, spray- and freeze-drying, fermentation, and extrusion enhanced the PPQ. The emerging non-thermal technologies impact on protein functionalities but require studies on the protein digestibility. How to accurately determine and how to improve the protein digestibility of a plant source remains a scientific and technological challenge that may be addressed by novel or combining existing processing techniques, as well as by exploring protein-enriched by-products of the food industry.

Ubiquitin proteasome system (UPS) activation in the cardiac hypertrophy of hyperthyroidism.

Ubiquitin proteasome system (UPS) is the main proteolytic pathway in eukaryotic cells. Changes in proteasome expression and activity have been associated to cardiovascular diseases as cardiac hypertrophy. Considering that cardiac hypertrophy is commonly associated to hyperthyroidism condition, the present study aimed to investigate the contribution of UPS in cardiac hypertrophy induced by thyroid hormones. Hyperthyroidism was induced in male Wistar rats by intraperitoneal injections of triiodothyronine (T3; 7  µg/100 g of body weight) for 7 days and confirmed by raised levels of total T3 and decreased levels of total T4. In addition, systolic blood pressure and heart rate were significantly increased in hyperthyroid group. Cardiac hypertrophy was confirmed in hyperthyroid group by increased heart weight/tibia length ratio and by increased α-MHC/ß-MHC relative expression. Both catalytic (20SPT) and regulatory subunits (19SPT) of the constitutive proteasome were upregulated in hyperthyroid hearts. In addition, the transcripts that encode immunoproteasome subunits were also elevated. Furthermore, ATP-dependent chymotrypsin-like activity (26SPT) was significantly increased in hyperthyroid group. Despite the upregulation and activation of UPS in hyperthyroid hearts, the content of polyubiquitinated proteins was unaltered in relation to control. Together, these results evidence the activation of cardiac proteasome by thyroid hormones, which possibly contribute to the maintenance of protein quality control and regulation of cardiac hypertrophy in response to thyroid hormones.

Evaluation of the biological quality of defatted pequi (Caryocar brasiliense Cambess) seed flour protein supplemented with lysine to rats (Rattus norvegicus) / Avaliação da qualidade biológica da proteína da farinha da semente do pequi (Caryocar brasiliense Cambess) desengordurada e suplementada com lisina em ratos (Rattus norvegicus)

ABSTRACT Objective In the biome of the Brazilian Cerrado, there are a lot of fruit tree species that stand out for their sensory quality and for presenting potentialities in the market of pulp and almond. Among these species, the pequi deserves attention because it has an almond rich in proteins and that is little explored. The aim of this study was to evaluate the biological quality of defatted pequi seed flour supplemented with lysine. Methods Two designs were done in this study; in the first, the animals were divided into four diet groups: control, protein-free, defatted pequi seed flour and defatted pequi seed flour supplemented with lysine. The protein-free diet was exempt of proteins and the other diets had a protein content of 10% and differed in protein source (casein: control diet or defatted pequi seed flour: test diets). The experiment lasted for 14 days. In the second design, 36 animals were used and followed-up for 28 days. The division of the experimental groups was kept, except for the protein-free diet group, which was excluded. By the end of the test, the animals were anaesthetised and euthanized. Results The results showed that the protein efficiency ratio of the control group was significantly higher than the other groups. For the other indices, the groups that received defatted pequi seed flour did not differ statistically among themselves. Conclusion These findings have shown an effect of supplementation on the protein efficiency ratio when comparing the test diets, however, when compared to the control group, no improvement was found.

RESUMO Objetivo O bioma cerrado é rico em espécies frutíferas que destacam-se por suas qualidades sensoriais e por apresentarem potencialidades no mercado de polpas e amêndoas. Dentre essas espécies, o pequi merece atenção porque possui uma amêndoa rica em proteínas e que é pouco explorada. Este estudo teve como objetivo avaliar a qualidade biológica da farinha da semente do pequi desengordurada e suplementada com lisina. Métodos Neste estudo foram feitos dois delineamentos: no primeiro os animais foram divididos em quatro grupos: controle, aprotéico, farinha da semente do pequi desengordurada e farinha da semente do pequi desengordurada suplementada com lisina. A dieta aprotéica era isenta de proteínas e as demais dietas apresentavam um teor de 10% de proteínas e diferiram quanto à fonte protéica (caseína: dieta controle e farinha da semente do pequi desengordurada: dietas testes). Esse experimento teve duração de 14 dias. No segundo delineamento, utilizou-se 36 animais que foram acompanhados por 28 dias, a divisão dos grupos experimentais foi mantida, exceto o grupo dieta aprotéica que foi excluído. Ao final dos experimentos, os animais foram anestesiados e eutanasiados. Resultados Os resultados mostraram que o coeficiente de eficiência protéica do grupo controle foi significativamente superior aos demais grupos. Para os demais índices biológicos de avaliação da qualidade protéica, os grupos que receberam a farinha da semente do pequi desengordurada não diferiram estatisticamente entre si. Conclusão Os achados mostraram um efeito da suplementação no coeficiente de eficiência protéica quando comparamos as dietas testes, no entanto, quando comparado ao grupo controle, não houve melhora.

Ubiquitin proteasome system (UPS) activation in the cardiac hypertrophy of hyperthyroidism

Ubiquitin proteasome system (UPS) is the main proteolytic pathway in eukaryotic cells. Changes in proteasome expression and activity have been associated to cardiovascular diseases as cardiac hypertrophy. Considering that cardiac hypertrophy is commonly associated to hyperthyroidism condition, the present study aimed to investigate the contribution of UPS in cardiac hypertrophy induced by thyroid hormones. Hyperthyroidism was induced in male Wistar rats by intraperitoneal injections of triiodothyronine (T3; 7 µg/100g of body weight) for 7 days and confirmed by raised levels of total T3 and decreased levels of total T4. In addition, systolic blood pressure and heart rate were significantly increased in hyperthyroid group. Cardiac hypertrophy was confirmed in hyperthyroid group by increased heart weight/tibia length ratio and by increased a-MHC/ß-MHC relative expression. Both catalytic (20SPT) and regulatory subunits (19SPT) of the constitutive proteasome were upregulated in hyperthyroid hearts. In addition, the transcripts that encode immunoproteasome subunits were also elevated. Furthermore, ATP-dependent chymotrypsin-like activity (26SPT) was significantly increased in hyperthyroid group. Despite the upregulation and activation of UPS in hyperthyroid hearts, the content of polyubiquitinated proteins was unaltered in relation to control. Together, these results evidence the activation of cardiac proteasome by thyroid hormones, which possibly contribute to the maintenance of protein quality control and regulation of cardiac hypertrophy in response to thyroid hormones.

Endoplasmic reticulum stress in autoimmune diseases: Can altered protein quality control and/or unfolded protein response contribute to autoimmunity? A critical review on Sjögren's syndrome.

For many years, researchers in the field of autoimmunity have focused on the role of the immune components in the etiopathogenesis of autoimmune diseases. However, some studies have demonstrated the importance of target tissues in their pathogenesis and the breach of immune tolerance. The immune system as well as target tissue cells (plasmatic, ß-pancreatic, fibroblast-like synoviocytes, thyroid follicular and epithelial cells of the lachrymal glands, salivary glands, intestine, bronchioles and renal tubules) share the characteristic of secretory cells with an extended endoplasmic reticulum (ER). The function of these cells depends considerably on a normal ER function and calcium homeostasis, so they can produce and secrete their main components, which include glycoproteins involved in antigenic presentation such as major histocompatibility complex (MHC) class I and II. All these proteins are synthesized and modified in the ER, and for this reason disturbances in the normal functions of this organelle such as protein folding, protein quality control, calcium homeostasis and redox balance, promote accumulation of unfolded or misfolded proteins, a condition known as ER stress. Autoimmune diseases are characterized by inflammation, which has been associated with an ER stress condition. Interestingly, patients with these diseases contain circulating auto-antibodies against chaperone proteins (such as Calnexin and GRP94), thus affecting the folding and assembly of MHC class I and II glycoproteins and their loading with peptide. The main purpose of this article is to review the involvement of the protein quality control and unfolded protein response (UPR) in the ER protein homeostasis (proteostasis) and their alterations in autoimmune diseases. In addition, we describe the interaction between ER stress and inflammation and evidences are shown of how autoimmune diseases are associated with an ER stress condition, with a special emphasis on the second most prevalent autoimmune rheumatic disease, Sjögren's syndrome.

Calidad proteica de la dieta en lactantes con desnutrición severa / Protein quality in the diet of infants with severe malnutrition

Introducción: la desnutrición severa infantil constituye un problema vigente en países pobres, porque los requerimientos nutrimentales se proporcionan de manera inadecuada. Las necesidades proteicas relacionadas con la tasa de crecimiento, se reflejan en la cantidad requerida de aminoácidos esenciales; del total de proteínas, la dieta de adultos debe contener 15 por ciento, y la de lactantes entre 33 y 37 por ciento de estos aminoácidos. La calidad proteica se obtiene calculando el escore de aminoácidos, a partir del cual se diseñó el patrón seguro para diferentes grupos de edades, que incluye composición en aminoácidos esenciales, sus proporciones y digestibilidad, y es adecuada cuando estas proporciones satisfacen los requerimientos de nitrógeno para crecimiento, síntesis, y reparación tisular. Objetivos: determinar la calidad proteica de la dieta de lactantes con desnutrición severa, ingresados en el Hospital Francisco Icaza Bustamante de Guayaquil, Ecuador, durante el periodo 2009-2010; y los específicos, diagnosticar el tipo de desnutrición severa de los pacientes, identificar el perfil de aminoácidos en la dieta de los casos de estudio, así como establecer el valor biológico de las proteínas dietéticas que reciben. Métodos: estudio de enfoque cuantitativo, observacional, descriptivo, analítico y de corte transversal, en lactantes con diagnóstico de desnutrición severa. La población incluyó a todos los pacientes con desnutrición severa, menores de 24 meses de edad; la muestra fue de 33 pacientes, basada en criterios de selección. Para evaluar calidad proteica se utilizó el Escore de Aminoácidos Corregido por Digestibilidad Proteica, comparando el perfil dietético con las necesidades del niño(AU)

Introduction: severe childhood malnutrition is a current health problem in poor countries because nutritional requirements are inadequately met. Protein needs related to growth rates are reflected in the volume required of essential amino acids. Of the total proteins, the diet of adults should contain 15 percent and that of infants between 33 and 37 percent of these amino acids. Protein quality was obtained by estimating the score of amino acids, starting from which a safe pattern was designed for different age groups, including the composition as to essential amino acids, their proportions and digestibility. It is considered to be adequate when these proportions meet the nitrogen requirements for growth, synthesis and tissue repair. Objectives: determine the protein quality of the diet of infants with severe malnutrition staying at Francisco Icaza Bustamante hospital in Guayaquil, Ecuador, during the period 2009-2010. Specific objectives are to diagnose the type of severe malnutrition of patients, identify the amino acid profile in the diet of the study cases, and establish the biological value of the diet proteins they receive. Methods: a quantitative cross-sectional analytical descriptive observational study was conducted of infants diagnosed with severe malnutrition. The study population included all the patients with severe malnutrition aged under 24 months. The sample was 33 patients, based on selection criteria. Protein quality was evaluated with the Protein Digestibility Corrected Amino Acid Score, comparing the dietary profile with the needs of the child. Results: statistical analysis showed that all patients had several limiting amino acids in their diet. Conclusions: the diet of infants with severe malnutrition has a poor protein quality, with an amino acid coefficient inadequate for synthesis functions and the consequent negative impact on growth and development(AU)

Aerobic exercise training rescues protein quality control disruption on white skeletal muscle induced by chronic kidney disease in rats.

We tested whether aerobic exercise training (AET) would modulate the skeletal muscle protein quality control (PQC) in a model of chronic kidney disease (CKD) in rats. Adult Wistar rats were evaluated in four groups: control (CS) or trained (CE), and 5/6 nephrectomy sedentary (5/6NxS) or trained (5/6NxE). Exercised rats were submitted to treadmill exercise (60 min., five times/wk for 2 months). We evaluated motor performance (tolerance to exercise on the treadmill and rotarod), cross-sectional area (CSA), gene and protein levels related to the unfolded protein response (UPR), protein synthesis/survive and apoptosis signalling, accumulated misfolded proteins, chymotrypsin-like proteasome activity (UPS activity), redox balance and heat-shock protein (HSP) levels in the tibialis anterior. 5/6NxS presented a trend towards to atrophy, with a reduction in motor performance, down-regulation of protein synthesis and up-regulation of apoptosis signalling; increases in UPS activity, misfolded proteins, GRP78, derlin, HSP27 and HSP70 protein levels, ATF4 and GRP78 genes; and increase in oxidative damage compared to CS group. In 5/6NxE, we observed a restoration in exercise tolerance, accumulated misfolded proteins, UPS activity, protein synthesis/apoptosis signalling, derlin, HSPs protein levels as well as increase in ATF4, GRP78 genes and ATF6α protein levels accompanied by a decrease in oxidative damage and increased catalase and glutathione peroxidase activities. The results suggest a disruption of PQC in white muscle fibres of CKD rats previous to the atrophy. AET can rescue this disruption for the UPR, prevent accumulated misfolded proteins and reduce oxidative damage, HSPs protein levels and exercise tolerance.