RESUMO
Objective. The aim of this study was to evaluate the association of the α-adducin-1 gene (ADD1) (Gly460Trp [rs4961]) polymorphism and its expression in association with renal dysfunction and sodium sensitivity in hypertensive patients in western Ukrainian population. Methods. One-hundred patients with essential arterial hypertension (EAH) and hypertensive-mediated target organ damage (stage 2), moderate, high, and very high cardiovascular risk were enrolled in case-control study. Sixty healthy individuals were assigned as controls. Sodium sensitivity and sodium resistance were determined by salt load reaction. The ADD1 (rs4961) genotyping was performed in RT-PCR. Results. The expression of the quantitative trait loci (eQTL) of ADD1 gene (rs4961) (chr4:2906707 [hg19]) was confirmed in 37 tissues and organs with 23 phenotypic traits. Two hundred eQTL associations revealed - all cis-variants (cis-QTL); 73 methylation QTL (mQTL), 34 splicing QTL (sQTL), 14 histone modification QTL (hQTL), 2 protein QTL (pQTL), 23 transcript utilization QTL (tuQTL), and 4 loci of incorporated long noncoding areas of RNA (lncRNA). GG-genotype unreliably enhances EAH risk (OR=1.92; 95%CI: 0.90-4.10; p=0.066). Sodium sensitivity was observed in 54.0% of patients and in 20.0% of controls (c2=17.89; p<0.001). Sodium sensitivity in T-allele carriers of the ADD1 gene (1378G>T; rs4961) dominated 12-fold in general (OR 95%CI: 2.24-64.29; p=0.001), in women - 4.71 times (OR 95%CI: 1.92-11.56; p<0.001), and in men - 4.09 times (OR 95%CI: 1.03-16.28; p=0.041). Sodium sensitivity elevated the likelihood of severe EAH twice (OR=2.19; OR 95%CI: 1.00-5.05; p=0.049). Conclusion. T-allele associates with sodium sensitivity in essential arterial hypertension patients and increases the risk of hypertension regardless the gender. Sodium sensitivity enhances the probability of severe essential arterial hypertension in observed population.
Assuntos
Proteínas de Ligação a Calmodulina , Locos de Características Quantitativas , Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Ucrânia/epidemiologia , Proteínas de Ligação a Calmodulina/genética , Estudos de Casos e Controles , Adulto , Hipertensão/genética , Hipertensão/epidemiologia , Polimorfismo de Nucleotídeo Único , Estudos de Coortes , Sódio/metabolismo , Idoso , Hipertensão Essencial/genética , Predisposição Genética para DoençaRESUMO
Cation conducting channelrhodopsins (ChRs) are a popular tool used in optogenetics to control the activity of excitable cells and tissues using light. ChRs with altered ion selectivity are in high demand for use in different cell types and for other specialized applications. However, a detailed mechanism of ion permeation in ChRs is not fully resolved. Here, we use complementary experimental and computational methods to uncover the mechanisms of cation transport and valence selectivity through the channelrhodopsin chimera, C1C2, in the high- and low-conducting open states. Electrophysiology measurements identified a single-residue substitution within the central gate, N297D, that increased Ca2+ permeability vs. Na+ by nearly two-fold at peak current, but less so at stationary current. We then developed molecular models of dimeric wild-type C1C2 and N297D mutant channels in both open states and calculated the PMF profiles for Na+ and Ca2+ permeation through each protein using well-tempered/multiple-walker metadynamics. Results of these studies agree well with experimental measurements and demonstrate that the pore entrance on the extracellular side differs from original predictions and is actually located in a gap between helices I and II. Cation transport occurs via a relay mechanism where cations are passed between flexible carboxylate sidechains lining the full length of the pore by sidechain swinging, like a monkey swinging on vines. In the mutant channel, residue D297 enhances Ca2+ permeability by mediating the handoff between the central and cytosolic binding sites via direct coordination and sidechain swinging. We also found that altered cation binding affinities at both the extracellular entrance and central binding sites underly the distinct transport properties of the low-conducting open state. This work significantly advances our understanding of ion selectivity and permeation in cation channelrhodopsins and provides the insights needed for successful development of new ion-selective optogenetic tools.
Assuntos
Cálcio , Channelrhodopsins , Simulação de Dinâmica Molecular , Sódio , Sódio/metabolismo , Cálcio/metabolismo , Channelrhodopsins/metabolismo , Channelrhodopsins/genética , Channelrhodopsins/química , Animais , Transporte de Íons , Humanos , Células HEK293 , Ativação do Canal IônicoRESUMO
Soil salinity is detrimental to plant growth and remains a major threat to crop productivity of the world. Plants employ various physiological and molecular mechanisms to maintain growth under salt stress. Identification of genes and genetic loci underlying plant salt tolerance holds the key to breeding salt tolerant crops. CIPK-CBL pathways regulate adaptive responses of plants (especially ion transport) to abiotic stresses via fine-tuned Ca2+ signal transduction. In this study, we showed that over-expression of OsCIPK17 in Arabidopsis enhanced primary root elongation under salt stress, which is in a Ca2+ dependent manner. Further investigation revealed that, under salt stress, OsCIPK17 transcript level was significantly induced and its protein moved from the cytosol to the tonoplast. Using both Y2H and BiFC, tonoplast-localised OsCBL2 and OsCBL3 were shown to interact with OsCIPK17. Interestingly, over-expressing salt-induced OsCBL2 or OsCBL3 in Arabidopsis led to enhanced primary root elongation under salt stress. In this process, OsCIPK17 was shown recruited to the tonoplast (similar to the effect of salt stress). Furthermore, transgenic Arabidopsis lines individually over-expressing OsCIPK17, OsCBL2 and OsCBL3 all demonstrated larger biomass and less Na + accumulation in the shoot under salt stress. All data combined suggest that OsCIPK17- OsCBL2/3 module is a major component of shoot Na+ exclusion and therefore plant salt tolerance, which is through enhanced Na + compartmentation into the vacuole in the root. OsCIPK17 and OsCBL2/3 are therefore potential genetic targets that can be used for delivering salt tolerant rice cultivars.
Assuntos
Arabidopsis , Oryza , Proteínas de Plantas , Brotos de Planta , Plantas Geneticamente Modificadas , Tolerância ao Sal , Sódio , Arabidopsis/genética , Arabidopsis/metabolismo , Oryza/genética , Oryza/metabolismo , Tolerância ao Sal/genética , Brotos de Planta/genética , Brotos de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Sódio/metabolismo , Regulação da Expressão Gênica de Plantas , Raízes de Plantas/genética , Raízes de Plantas/metabolismoRESUMO
It is normally supposed that populations of the same species should evolve shared mechanisms of adaptation to common stressors due to evolutionary constraint. Here, we describe a system of within-species local adaptation to coastal habitats, Brassica fruticulosa, and detail surprising strategic variability in adaptive responses to high salinity. These different adaptive responses in neighboring populations are evidenced by transcriptomes, diverse physiological outputs, and distinct genomic selective landscapes. In response to high salinity Northern Catalonian populations restrict root-to-shoot Na+ transport, favoring K+ uptake. Contrastingly, Central Catalonian populations accumulate Na+ in leaves and compensate for the osmotic imbalance with compatible solutes such as proline. Despite contrasting responses, both metapopulations were salinity tolerant relative to all inland accessions. To characterize the genomic basis of these divergent adaptive strategies in an otherwise non-saline-tolerant species, we generate a long-read-based genome and population sequencing of 18 populations (nine inland, nine coastal) across the B. fruticulosa species range. Results of genomic and transcriptomic approaches support the physiological observations of distinct underlying mechanisms of adaptation to high salinity and reveal potential genetic targets of these two very recently evolved salinity adaptations. We therefore provide a model of within-species salinity adaptation and reveal cryptic variation in neighboring plant populations in the mechanisms of adaptation to an important natural stressor highly relevant to agriculture.
Assuntos
Adaptação Fisiológica , Brassica , Salinidade , Brassica/genética , Brassica/fisiologia , Brassica/metabolismo , Adaptação Fisiológica/genética , Tolerância ao Sal/genética , Transcriptoma , Genoma de Planta , Regulação da Expressão Gênica de Plantas , Variação Genética , Sódio/metabolismo , EcossistemaRESUMO
Neurotransmitter:sodium symporters (NSSs) play critical roles in neural signaling by regulating neurotransmitter uptake into cells powered by sodium electrochemical gradients. Bacterial NSSs orthologs, including MhsT from Bacillus halodurans, have emerged as model systems to understand the structural motifs of alternating access in NSSs and the extent of conservation of these motifs across the family. Here, we apply a computational/experimental methodology to illuminate the conformational landscape of MhsT alternating access. Capitalizing on our recently developed method, Sampling Protein Ensembles and Conformational Heterogeneity with AlphaFold2 (SPEACH_AF), we derived clusters of MhsT models spanning the transition from inward-facing to outward-facing conformations. Systematic application of double electron-electron resonance (DEER) spectroscopy revealed ligand-dependent movements of multiple structural motifs that underpin MhsT's conformational cycle. Remarkably, comparative DEER analysis in detergent micelles and lipid nanodiscs highlights the profound effect of the environment on the energetics of conformational changes. Through experimentally derived selection of collective variables, we present a model of ion and substrate-powered transport by MhsT consistent with the conformational cycle derived from DEER. Our findings not only advance the understanding of MhsT's function but also uncover motifs of conformational dynamics conserved within the broader context of the NSS family and within the LeuT-fold class of transporters. Importantly, our methodological blueprint introduces an approach that can be applied across a diverse spectrum of transporters to describe their conformational landscapes.
Assuntos
Proteínas de Bactérias , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/química , Conformação Proteica , Bacillus/metabolismo , Sódio/metabolismo , Espectroscopia de Ressonância de Spin Eletrônica/métodos , Neurotransmissores/metabolismo , Modelos MolecularesRESUMO
The purpose of this study was to determine the effect of hydration status on the change in sweat sodium (Na+), chloride (Cl-), and potassium (K+) concentrations during exercise-heat stress. Fifteen subjects (Six female, nine male; 29 ± 9 y; 71 ± 14 kg) completed 90 min of cycling (81% HRmax) in the heat (~33°C, 42% rh) with fluid replacement to maintain euhydration (EUH) or without fluid to dehydrate to 2.4 ± 0.4% body mass loss (DEH). Sweat was collected from the forehead (FH), right scapula (SCAP), and left (LVFA) and right (RVFA) ventral forearms using the absorbent pad technique at the beginning (0-30 min) and end of exercise (60-90 min). Sweat was analyzed for Na+, Cl-, and K+ concentrations using ion chromatography. Data are reported as mean ± SD or median ± IQR. There were no differences (Paired t-tests or Wilcoxon signed-rank tests) between EUH and DEH in the change in sweat Na+ (FH: 24.3 ± 21.5 vs. 30.8 ± 22.4 mmol/L; SCAP: 9.7 ± 6.2 vs. 9.6 ± 8.2 mmol/L; LVFA: 7.5 ± 6.0 vs. 5.6 ± 5.9 mmol/L; RVFA: 8.2 ± 8.6 vs. 7.8 ± 5.2 mmol/L), sweat Cl-, or sweat K+ at any site (p = 0.07-0.99). The change in sweat electrolyte concentrations during 90 min of exercise in the heat was not significantly influenced by mild dehydration in recreational to moderately-trained male and female athletes.
Assuntos
Desidratação , Exercício Físico , Potássio , Sódio , Suor , Humanos , Feminino , Masculino , Desidratação/metabolismo , Desidratação/fisiopatologia , Suor/metabolismo , Suor/química , Adulto , Exercício Físico/fisiologia , Sódio/metabolismo , Sódio/análise , Potássio/metabolismo , Potássio/análise , Cloretos/metabolismo , Cloretos/análise , Equilíbrio Hidroeletrolítico/fisiologia , Sudorese/fisiologia , Adulto Jovem , Eletrólitos/metabolismo , Eletrólitos/análise , Temperatura AltaRESUMO
BACKGROUND: Vibrio natriegens, a halophilic marine γ-proteobacterium, holds immense biotechnological potential due to its remarkably short generation time of under ten minutes. However, the highest growth rates have been primarily observed on complex media, which often suffer from batch-to-batch variability affecting process stability and performance. Consistent bioprocesses necessitate the use of chemically defined media, which are usually optimized for fermenters with pH and dissolved oxygen tension (DOT) regulation, both of which are not applied during early-stage cultivations in shake flasks or microtiter plates. Existing studies on V. natriegens' growth on mineral media report partially conflicting results, and a comprehensive study examining the combined effects of pH buffering, sodium concentration, and medium osmolality is lacking. RESULTS: This study evaluates the influence of sodium concentration, pH buffering, and medium osmolality on the growth of V. natriegens under unregulated small-scale conditions. The maximum growth rate, time of glucose depletion, as well as the onset of stationary phase were observed through online-monitoring the oxygen transfer rate. The results revealed optimal growth conditions at an initial pH of 8.0 with a minimum of 300 mM MOPS buffer for media containing 20 g/L glucose or 180 mM MOPS for media with 10 g/L glucose. Optimal sodium chloride supplementation was found to be between 7.5 and 15 g/L, lower than previously reported ranges. This is advantageous for reducing industrial corrosion issues. Additionally, an osmolality range of 1 to 1.6 Osmol/kg was determined to be optimal for growth. Under these optimized conditions, V. natriegens achieved a growth rate of 1.97 ± 0.13 1/h over a period of 1 h at 37 °C, the highest reported rate for this organism on a mineral medium. CONCLUSION: This study provides guidelines for cultivating V. natriegens in early-stage laboratory settings without pH and DOT regulation. The findings suggest a lower optimal sodium chloride range than previously reported and establish an osmolality window for optimal growth, thereby advancing the understanding of V. natriegens' physiology. In addition, this study offers a foundation for future research into the effects of different ions and carbon sources on V. natriegens.
Assuntos
Técnicas de Cultura Celular por Lotes , Meios de Cultura , Vibrio , Concentração de Íons de Hidrogênio , Concentração Osmolar , Vibrio/crescimento & desenvolvimento , Vibrio/efeitos dos fármacos , Meios de Cultura/química , Técnicas de Cultura Celular por Lotes/métodos , Sódio/metabolismo , Sódio/farmacologia , Oxigênio/metabolismo , Reatores BiológicosRESUMO
Sodium imbalance is a common electrolyte disturbance in COVID-19, often linked to disruptions in hormonal regulation. This review explores the relationship between sodium dysregulation and endocrine disturbances, particularly focusing on primary and secondary hypothyroidism, hypocortisolism, and the renin-angiotensin-aldosterone system (RAAS). Hypocortisolism in COVID-19, due to adrenal insufficiency or secondary to pituitary dysfunction, can lead to hyponatremia through inadequate cortisol levels, which impair renal free water excretion and enhance antidiuretic hormone (ADH) secretion. Similarly, hypothyroidism is associated with decreased renal blood flow and the glomerular filtration rate (GFR), which also increases ADH activity, leading to water retention and dilutional hyponatremia. Furthermore, COVID-19 can disrupt RAAS (primarily through its interaction with the angiotensin-converting enzyme 2 (ACE2) receptor), diminishing aldosterone secretion and further contributing to sodium loss and hyponatremia. These hormonal disruptions suggest that sodium imbalance in COVID-19 is multifactorial and warrants further investigation into the complex interplay between COVID-19, endocrine function, and sodium homeostasis. Future research should focus on understanding these mechanisms to develop management algorithms that address both sodium imbalance and underlying hormonal disturbances in order to improve prognosis and outcomes in COVID-19 patients.
Assuntos
COVID-19 , Hiponatremia , Sistema Renina-Angiotensina , SARS-CoV-2 , Humanos , COVID-19/complicações , COVID-19/metabolismo , Hiponatremia/etiologia , Hiponatremia/metabolismo , Doenças do Sistema Endócrino/etiologia , Doenças do Sistema Endócrino/metabolismo , Sódio/metabolismo , Hipotireoidismo/metabolismo , Hipotireoidismo/complicaçõesRESUMO
The two-kidney, one-clip (2K1C) Goldblatt rodent model elicits a reduction in renal blood flow (RBF) in the clipped kidney (CK). The reduced RBF and oxygen bio-ability causes the accumulation of the tricarboxylic cycle intermediary, α-ketoglutarate, which activates the oxoglutarate receptor-1 (OXGR1). In the kidney, OXGR1 is abundantly expressed in intercalated cells (ICs) of the collecting duct (CD), thus contributing to sodium transport and electrolyte balance. The (pro)renin receptor (PRR), a member of the renin-angiotensin system (RAS), is a key regulator of sodium reabsorption and blood pressure (BP) that is expressed in ICs. The PRR is upregulated in 2K1C rats. Here, we tested the hypothesis that chronic reduction in RBF in the CK leads to OXGR1-dependent PRR upregulation in the CD and alters sodium balance and BP in 2K1C mice. To determine the role of OXGR1 in regulating the PRR in the CDs during renovascular hypertension, we performed 2K1C Goldblatt surgery (clip = 0.13 mm internal gap, 14 days) in two groups of male mice: (1) mice treated with Montelukast (OXGR1 antagonist; 5 mg/Kg/day); (2) OXGR1-/- knockout mice. Wild-type and sham-operated mice were used as controls. After 14 days, 2K1C mice showed increased systolic BP (SBP) (108 ± 11 vs. control 82 ± 5 mmHg, p < 0.01) and a lower natriuretic response after the saline challenge test. The CK group showed upregulation of erythropoietin, augmented α-ketoglutarate, and increased PRR expression in the renal medulla. The CK of OXGR1 knockout mice and mice subjected to the OXGR1 antagonist elicited impaired PRR upregulation, attenuated SBP, and better natriuretic responses. In 2K1C mice, the effect of reduced RBF on the OXGR1-dependent PRR upregulation in the CK may contribute to the anti-natriuretic and increased SBP responses.
Assuntos
Túbulos Renais Coletores , Receptores de Superfície Celular , Sódio , Regulação para Cima , Animais , Camundongos , Túbulos Renais Coletores/metabolismo , Receptores de Superfície Celular/metabolismo , Receptores de Superfície Celular/genética , Masculino , Sódio/metabolismo , Hipertensão Renovascular/metabolismo , Hipertensão Renovascular/genética , Pressão Sanguínea , Camundongos Knockout , Receptor de Pró-Renina , Rim/metabolismo , Modelos Animais de Doenças , Sistema Renina-Angiotensina , Camundongos Endogâmicos C57BL , Receptores Acoplados a Proteínas G/metabolismo , Receptores Acoplados a Proteínas G/genética , Receptores Purinérgicos P2RESUMO
Neuronal hyperexcitability is a key element of many neurodegenerative disorders including the motor neuron disease Amyotrophic Lateral Sclerosis (ALS), where it occurs associated with elevated late sodium current (INaL). INaL results from incomplete inactivation of voltage-gated sodium channels (VGSCs) after their opening and shapes physiological membrane excitability. However, dysfunctional increases can cause hyperexcitability-associated diseases. Here we reveal the atypical binding mechanism which explains how the neuroprotective ALS-treatment drug riluzole stabilises VGSCs in their inactivated state to cause the suppression of INaL that leads to reversed cellular overexcitability. Riluzole accumulates in the membrane and enters VGSCs through openings to their membrane-accessible fenestrations. Riluzole binds within these fenestrations to stabilise the inactivated channel state, allowing for the selective allosteric inhibition of INaL without the physical block of Na+ conduction associated with traditional channel pore binding VGSC drugs. We further demonstrate that riluzole can reproduce these effects on a disease variant of the non-neuronal VGSC isoform Nav1.4, where pathologically increased INaL is caused directly by mutation. Overall, we identify a model for VGSC inhibition that produces effects consistent with the inhibitory action of riluzole observed in models of ALS. Our findings will aid future drug design and supports research directed towards riluzole repurposing.
Assuntos
Esclerose Lateral Amiotrófica , Fármacos Neuroprotetores , Riluzol , Riluzol/farmacologia , Esclerose Lateral Amiotrófica/tratamento farmacológico , Esclerose Lateral Amiotrófica/metabolismo , Esclerose Lateral Amiotrófica/genética , Humanos , Fármacos Neuroprotetores/farmacologia , Canais de Sódio Disparados por Voltagem/metabolismo , Canais de Sódio Disparados por Voltagem/química , Células HEK293 , Animais , Sódio/metabolismo , Neurônios Motores/efeitos dos fármacos , Neurônios Motores/metabolismoRESUMO
Every individual at some point encounters the progressive biological process of aging, which is considered one of the major risk factors for common diseases. The main drivers of aging are oxidative stress, senescence, and reactive oxygen species (ROS). The renin-angiotensin-aldosterone system (RAAS) includes several systematic processes for the regulation of blood pressure, which is caused by an imbalance of electrolytes. During activation of the RAAS, binding of angiotensin II (ANG II) to angiotensin II type 1 receptor (AGTR1) activates intracellular nicotinamide adenine dinucleotide phosphate (NADPH) oxidase to generate superoxide anions and promote uncoupling of endothelial nitric oxide (NO) synthase, which in turn decreases NO availability and increases ROS production. Promoting oxidative stress and DNA damage mediated by ANG II is tightly regulated. Individuals with sodium deficiency-associated diseases such as Gitelman syndrome (GS) and Bartter syndrome (BS) show downregulation of inflammation-related processes and have reduced oxidative stress and ROS. Additionally, the histone deacetylase sirtuin-1 (SIRT1) has a significant impact on the aging process, with reduced activity with age. However, GS/BS patients generally sustain higher levels of sirtuin-1 (SIRT1) activity than age-matched healthy individuals. SIRT1 expression in GS/BS patients tends to be higher than in healthy age-matched individuals; therefore, it can be assumed that there will be a trend towards healthy aging in these patients. In this review, we highlight the importance of the hallmarks of aging, inflammation, and the RAAS system in GS/BS patients and how this might impact healthy aging. We further propose future research directions for studying the etiology of GS/BS at the molecular level using patient-derived renal stem cells and induced pluripotent stem cells.
Assuntos
Envelhecimento , Estresse Oxidativo , Sistema Renina-Angiotensina , Sirtuína 1 , Humanos , Sistema Renina-Angiotensina/fisiologia , Envelhecimento/metabolismo , Sirtuína 1/metabolismo , Sirtuína 1/genética , Espécies Reativas de Oxigênio/metabolismo , Síndrome de Gitelman/metabolismo , Síndrome de Gitelman/genética , Síndrome de Bartter/metabolismo , Síndrome de Bartter/genética , Sódio/metabolismo , Angiotensina II/metabolismoRESUMO
Expansins are cell wall (CW) proteins that mediate the CW loosening and regulate salt tolerance in a positive or negative way. However, the role of Populus trichocarpa expansin A6 (PtEXPA6) in salt tolerance and the relevance to cell wall loosening is still unclear in poplars. PtEXPA6 gene was transferred into the hybrid species, Populus alba × P. tremula var. glandulosa (84K) and Populus tremula × P. alba INRA '717-1B4' (717-1B4). Under salt stress, the stem growth, gas exchange, chlorophyll fluorescence, activity and transcription of antioxidant enzymes, Na+ content, and Na+ flux of root xylem and petiole vascular bundle were investigated in wild-type and transgenic poplars. The correlation analysis and principal component analysis (PCA) were used to analyze the correlations among the characteristics and principal components. Our results show that the transcription of PtEXPA6 was downregulated upon a prolonged duration of salt stress (48 h) after a transient increase induced by NaCl (100 mM). The PtEXPA6-transgenic poplars of 84K and 717-1B4 showed a greater reduction (42-65%) in stem height and diameter growth after 15 days of NaCl treatment compared with wild-type (WT) poplars (11-41%). The Na+ accumulation in roots, stems, and leaves was 14-83% higher in the transgenic lines than in the WT. The Na+ buildup in the transgenic poplars affects photosynthesis; the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT); and the transcription of PODa2, SOD [Cu-Zn], and CAT1. Transient flux kinetics showed that the Na+ efflux of root xylem and leaf petiole vascular bundle were 1.9-3.5-fold greater in the PtEXPA6-transgenic poplars than in the WT poplars. PtEXPA6 overexpression increased root contractility and extensibility by 33% and 32%, indicating that PtEXPA6 increased the CW loosening in the transgenic poplars of 84K and 717-1B4. Noteworthily, the PtEXPA6-promoted CW loosening was shown to facilitate Na+ efflux of root xylem and petiole vascular bundle in the transgenic poplars. We conclude that the overexpression of PtEXPA6 leads to CW loosening that facilitates the radial translocation of Na+ into the root xylem and the subsequent Na+ translocation from roots to leaves, resulting in an excessive Na+ accumulation and consequently, reducing salt tolerance in transgenic poplars. Therefore, the downregulation of PtEXPA6 in NaCl-treated Populus trichocarpa favors the maintenance of ionic and reactive oxygen species (ROS) homeostasis under long-term salt stress.
Assuntos
Regulação da Expressão Gênica de Plantas , Proteínas de Plantas , Plantas Geneticamente Modificadas , Populus , Estresse Salino , Sódio , Populus/genética , Populus/metabolismo , Populus/crescimento & desenvolvimento , Populus/efeitos dos fármacos , Sódio/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Xilema/metabolismo , Xilema/genética , Raízes de Plantas/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Tolerância ao Sal/genética , Transporte BiológicoRESUMO
Retinoids are known to improve the condition of the skin. Transepithelial transport of sodium and chloride ions is important for proper skin function. So far, the effect of applying vitamin A preparations to the skin on ion transport has not been evaluated. In the study, electrophysiological parameters, including transepithelial electric potential (PD) and transepithelial resistance (R), of rabbit skin specimens after 24 h exposure to retinol ointment (800 mass units/g) were measured in a modified Ussing chamber. The R of the fragments incubated with retinol was significantly different than that of the control skin samples incubated in iso-osmotic Ringer solution. For the controls, the PD values were negative, whereas the retinol-treated specimens revealed positive PD values. Mechanical-chemical stimulation with the use of inhibitors of the transport of sodium (amiloride) or chloride (bumetanide) ions revealed specific changes in the maximal and minimal PD values measured for the retinol-treated samples. Retinol was shown to slightly modify the transport pathways of sodium and chloride ions. In particular, an intensification of the chloride ion secretion from keratinocytes was observed. The proposed action may contribute to deep hydration and increase skin tightness, limiting the action of other substances on its surface.
Assuntos
Transporte de Íons , Pele , Vitamina A , Animais , Coelhos , Vitamina A/farmacologia , Vitamina A/metabolismo , Transporte de Íons/efeitos dos fármacos , Pele/metabolismo , Pele/efeitos dos fármacos , Pomadas , Sódio/metabolismo , Cloretos/metabolismoRESUMO
Sodium serves as one of the primary cations in the central nervous system, playing a crucial role in maintaining normal brain function. In this study, we investigated alterations in sodium concentrations in the brain and/or cerebrospinal fluid across multiple models, including an aging model, a stroke model, a nitroglycerin (NTG)-induced rat migraine model, a familial hemiplegic migraine type 2 (FHM2) mouse model, and a transgenic mouse model of Alzheimer's disease (AD). Our results reveal that older rats exhibited higher sodium concentrations in cerebrospinal fluid (CSF), plasma, and various brain regions compared to their younger counterparts. Additionally, findings from the stroke model demonstrated a significant increase in sodium in the ischemic/reperfused region, accompanied by a decrease in potassium and an elevated sodium/potassium ratio. However, we did not detect significant changes in sodium in the NTG-induced rat migraine model or the FHM2 mouse model. Furthermore, AD transgenic mice showed no significant differences in sodium levels compared to wild-type mice in CSF, plasma, or the hippocampus. These results underscore the nuanced regulation of sodium homeostasis in various neurological conditions and aging, providing valuable insights into potential mechanisms underlying these alterations.
Assuntos
Envelhecimento , Doença de Alzheimer , Modelos Animais de Doenças , Camundongos Transgênicos , Transtornos de Enxaqueca , Sódio , Acidente Vascular Cerebral , Animais , Doença de Alzheimer/metabolismo , Sódio/líquido cefalorraquidiano , Sódio/sangue , Sódio/metabolismo , Ratos , Camundongos , Masculino , Acidente Vascular Cerebral/metabolismo , Transtornos de Enxaqueca/metabolismo , Transtornos de Enxaqueca/induzido quimicamente , Transtornos de Enxaqueca/sangue , Humanos , Nitroglicerina/farmacologia , Traumatismo por Reperfusão/metabolismo , Encéfalo/metabolismo , Ratos Sprague-Dawley , Enxaqueca com AuraRESUMO
KEY MESSAGE: Sodium treatment caused the sodium ion accumulation at the milk stage of immature rice grains which in turn triggered the overproduction of reactive oxygen species and oxidative damage. The tolerant cultivar showed an enhanced antioxidative response and induced expressions of OsNHX and OsHKT ion-transporters. Sodium chloride-(NaCl) induced soil salinity is a major constraint hindering global rice production. Amongst its constituent ions, sodium (Na+) is known to be the main driver of toxicity under salt stress. The present investigation aims to measure the impacts of excess Na+ during rice grain filling using two Indica rice cultivars with opposite tolerances to salt (salt tolerant: Panvel-3, salt-sensitive: Sahyadri-3) mainly via oxidative and responsive antioxidative pathways. Plants were treated with Na+-specific treatments and NaCl with equimolar Na+ levels (100 mM) at the initiation of the reproductive phase. Stressed and control plants were harvested at three different grain-filling stages- early milk, milk, and dough and assessed for ion accumulation and oxidative damage/antioxidant responses under Na+ stress. Na+ toxicity triggered reactive oxygen species (ROS) production and upregulated the responsive enzymatic antioxidants. Na+ stress also increased the nitric oxide (NO) levels and the activity of nitrate reductase in immature grains. Differential expression levels of OsNHX and OsHKT transporters were observed in response to Na+ stress. Mature grains displayed a high accumulation of Na+ along with reduced K+ content and elevated Na+/K+ under high Na+ availability. The alterations in mature grains' sugar, starch, and protein content were also observed in response to the Na+ stress. Overall, the salt-tolerant cultivar displayed higher antioxidant activities and a lower rate of ROS generation in response to the Na+ stress. Results suggested a link between Na+ accumulation, Na+-mediated stress responses via anti/-oxidant pathways, and the grain-filling process in both rice cultivars.
Assuntos
Antioxidantes , Regulação da Expressão Gênica de Plantas , Oryza , Estresse Oxidativo , Espécies Reativas de Oxigênio , Sódio , Oryza/metabolismo , Oryza/genética , Oryza/efeitos dos fármacos , Antioxidantes/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Sódio/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Grão Comestível/metabolismo , Grão Comestível/efeitos dos fármacos , Óxido Nítrico/metabolismo , Cloreto de Sódio/farmacologia , Estresse Salino , Sementes/efeitos dos fármacos , Sementes/metabolismoRESUMO
There is a consensus that electroneutral Na+/H+ exchangers (NHEs) are important in branchial Na+ uptake in freshwater fish. There is also widespread belief, based on mammalian data, that EIPA [5-(N-ethyl-N-isopropyl)-amiloride]], and HMA [5-(N,N-hexamethylene)-amiloride)] are more potent and specific in blocking Na+ uptake than amiloride. We evaluated this idea by testing the three drugs at 10-7 to 10-4 M, i.e. 0.1 to 100 µM in two model species, rainbow trout (Oncorhynchus mykiss) and goldfish (Carassius auratus), using 22Na+ to measure unidirectional Na+ influx and efflux rates. In both species, the potency order for inhibiting unidirectional Na+ influx was HMA > amiloride > EIPA (IC50 values in the 10-70 µM range), very different from in mammals. At 100 µM, all three drugs inhibited Na+ influx by >90% in both species, except for amiloride in goldfish (65%). However, at 60-100 µM, all three drugs also stimulated unidirectional Na+ efflux rates, indicating non-specific effects. In trout, HMA and EIPA caused significant increases (2.1- to 2.3-fold) in efflux rates, whereas in goldfish, significant efflux elevations were greater (3.1- to 7.2-fold) with all three drugs. We conclude that the inhibitory potency profile established in mammals does not apply to the NHEs in fish gills, that non-specific effects on Na+ efflux rates are a serious concern, and that EIPA and HMA offer no clear benefits in terms of potency or specificity. Considering its much lower cost, we recommend amiloride as the drug of choice for in vivo experiments on freshwater fishes.
Assuntos
Amilorida , Carpa Dourada , Sódio , Animais , Amilorida/farmacologia , Amilorida/análogos & derivados , Carpa Dourada/metabolismo , Sódio/metabolismo , Brânquias/metabolismo , Brânquias/efeitos dos fármacos , Oncorhynchus mykiss/metabolismo , Água Doce , Trocadores de Sódio-Hidrogênio/metabolismo , Trocadores de Sódio-Hidrogênio/antagonistas & inibidores , Transporte de Íons/efeitos dos fármacos , Truta/metabolismoRESUMO
Freshwater fish that are acutely exposed to copper (Cu) can experience disturbances of ion regulation and ammonia excretion. Temperature has been shown to affect Cu bioaccumulation and toxicity in fish, but the focus has largely been on warm temperature effects. Yet, acclimation of freshwater fish to near-freezing temperatures encountered during the winter of temperate regions can challenge fish condition and physiology, including ion regulation. Thus, temperate freshwater fish might be particularly sensitive to Cu in the winter. We investigated how winter cold affects acute Cu bioaccumulation and toxicity in juvenile brook char (Salvelinus fontinalis). Following gradual acclimation to cold temperature (-2 °C/week from 14 °C, then 4 weeks at 3 °C) vs. a warmer temperature around the species thermal optimum (14 °C for 9 weeks), and following a cold challenge (-3 °C/day from 14 °C, then 24 h at 3 °C) vs. a cold acclimation (-2 °C/week from 14 °C, then 13 weeks at 3 °C), we measured gill-Cu bioaccumulation, net fluxes of ammonia (NH3), chloride (Cl-) and net and unidirectional fluxes of sodium (Na+) over a 30-h Cu exposure. Overall, winter cold did not appear to be challenging to brook char, as cold-acclimated fish had a higher fish condition and showed no sign of ion regulation impairment or increased Cu sensitivity. Contrary to our prediction, we found that Cu bioaccumulation over a 30-h Cu exposure was not significantly affected by acclimation temperature. Effects of temperature on Cu physiological effects were relatively limited (mainly on inhibition of Na+ influx and of NH3 excretion), with slightly greater effects observed in 14 °C-acclimated fish.
Assuntos
Amônia , Temperatura Baixa , Cobre , Brânquias , Estações do Ano , Truta , Poluentes Químicos da Água , Animais , Truta/metabolismo , Truta/fisiologia , Poluentes Químicos da Água/toxicidade , Cobre/toxicidade , Amônia/toxicidade , Amônia/metabolismo , Brânquias/metabolismo , Brânquias/efeitos dos fármacos , Bioacumulação , Sódio/metabolismo , Cloretos/toxicidade , Cloretos/metabolismo , AclimataçãoRESUMO
High-affinity potassium transporters (HKTs) are well known proteins that govern the partitioning of Na+ between roots and shoots. Six HvHKTs were identified in barley and designated as HvHKT1.1, HvHKT1.3, HvHKT1.4, HvHKT1.5, HvHKT2.1 and HvHKT2.2 according to their similarity to previously reported OsHKTs. Among these HvHKTs, HvHKT1.4 was highly up-regulated under salinity stress in both leaves and roots of Golden Promise. Subcellular localization analysis showed that HvHKT1.4 is a plasma-membrane-localized protein. The knockout mutants of HvHKT1.4 showed greater salinity sensitivity and higher Na+ concentration in leaves than wild-type plants. Haplotype analysis of HvHKT1.4 in 344 barley accessions showed 15 single nucleotide substitutions in the CDS region, belonging to five haplotypes. Significant differences in mean salinity damage scores, leaf Na+ contents and Na+/K+ were found between Hap5 and other haplotypes with Hap5 showing better salinity tolerance. The results indicated that HvHKT1.4 can be an effective target in improving salinity tolerance through ion homeostasis.
Assuntos
Hordeum , Proteínas de Plantas , Tolerância ao Sal , Hordeum/genética , Hordeum/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Tolerância ao Sal/genética , Sódio/metabolismo , Potássio/metabolismo , Proteínas de Transporte de Cátions/genética , Proteínas de Transporte de Cátions/metabolismo , Regulação da Expressão Gênica de Plantas , Haplótipos , Folhas de Planta/metabolismo , Folhas de Planta/genética , Raízes de Plantas/metabolismo , Raízes de Plantas/genética , SalinidadeRESUMO
Soil salinity significantly limits rice productivity, but it is poorly understood how excess sodium (Na+) is delivered to the grains at the reproductive stage. Here, we functionally characterized OsHAK4, a member of the clade IV HAK/KUP/KT transporter subfamily in rice. OsHAK4 was localized to the plasma membrane and exhibited influx transport activity for Na+, but not for K+. Analysis of organ- and growth stage-dependent expression patterns showed that very low expression levels of OsHAK4 were detected at the vegetative growth stage, but its high expression in uppermost node I, peduncle, and rachis was found at the reproductive stage. Immunostaining indicated OsHAK4 localization in the phloem region of node I, peduncle, and rachis. Knockout of OsHAK4 did not affect the growth and Na+ accumulation at the vegetative stage. However, at the reproductive stage, the hak4 mutants accumulated higher Na+ in the peduncle, rachis, husk, and brown rice compared to the wild-type rice. Element imaging revealed higher Na+ accumulation at the phloem region of the peduncle in the mutants. These results indicate that OsHAK4 plays a crucial role in retrieving Na+ from the phloem in the upper nodes, peduncle, and rachis, thereby preventing Na+ distribution to the grains at the reproductive stage of rice.