Search Results (47)

Rising global temperatures lead to a continuous increase in the frequency and intensity of extreme weather events, such as droughts and floods, posing serious threats to terrestrial homeotherms. However, adaptive changes in respiratory metabolism and molecular mechanisms in lung tissues of small mammals under extreme water shortage conditions remain unclear. This study hypothesized that small desert mammals can adapt to extreme water shortage environments by regulating the plasticity of lung tissue gene expression and respiratory metabolism. Using 29 wild-caught Siberian jerboas (Orientallactaga sibirica) as subjects, we implemented a 12-day complete water deprivation protocol to simulate extreme aridity. Body weight, food intake, and daily energy expenditure (DEE) were monitored throughout the experiment. Whole-transcriptome sequencing of lung tissues was performed to profile mRNA, circRNA, and miRNA expression, with competitive endogenous RNA (ceRNA) network analysis to explore molecular mechanisms underlying lung adaptation to water deprivation. Over the 12-day water deprivation (WS) period, Orientallactaga sibirica (O. sibirica) exhibited a 30.3% reduction in body mass and a 68.1% decrease in food intake relative to the baseline level. DEE during the peak activity period at the end of the experiment was 12.6% lower in the WS group compared to the control group. In lung tissue, structural integrity-related genes (Mybl2, Ccnb1) were downregulated. A key finding was that circ_0015576 exhibits a significant positive correlation with the potassium channel gene Kcnk15 and a robust negative correlation with miR-503-5p—suggesting that circ_0015576 functions as a competing endogenous RNA (ceRNA) to sequester miR-503-5p and thereby derepress Kcnk15 expression. Core regulatory genes (ApoA4, Dusp15 etc.) were also coordinately downregulated. Collectively, these results indicate that O. sibirica reduces overall energy expenditure, which may be associated with lung gene expression plasticity, such as those related with lung cell proliferation, pulmonary function, and gas exchange efficiency. This metabolic downregulation facilitates energy conservation under severe water scarcity. Full article

Amyotrophic lateral sclerosis (ALS) is a multisystem progressive neurodegenerative disease. A recent theory of ALS onsetting pathogenesis proposed that the initiating primary damage is an acquired irreversible intrafusal proprioceptive terminal PIEZO2 channelopathy with underlying genetic and environmental risk factors. This Piezo2 channelopathy may also disrupt the ultrafast proton-based oscillatory signaling to motor neurons through vesicular transporter 1 (VGLUT1) and to the hippocampus through VGLUT2. As a result, it may gradually degenerate motor neurons in which process K_v1.2 ion channels are gradually depleted. It also gradually depletes heat shock transcription factor-1 (HSF-1) in the hippocampus, hence negatively affecting adult hippocampal neurogenesis. Syndecans, especially syndecan-3 (SDC3) in the nervous system, may act as critical players in the maintenance of the crosstalk between Piezo ion channels. Hence, our goal was to reanalyze the potential pathogenic gene variants from the cohort of our previous ALS study with a special focus on the aforementioned genes. Reanalysis of data formerly acquired by whole-exome sequencing of 21 non-related adult ALS patients was carried out with a focus on 28 genes. Accordingly, we identified charge-altering variants of SDC3 in 13 patients out of 21 that may contribute to the impairment of the Piezo crosstalk, and the progressive loss of the proposed proton-based signaling to motor neurons and to the hippocampus. A variant of uncertain significance was identified in the KCNA2 gene that may facilitate the faster loss of K_v1.2 ion function on motor neurons when Piezo2 channelopathy prevails. Not to mention that one variant was identified in the potassium current rectifying ion channels encoding KCNK1 and KCNK16 genes that may also propel the ALS disease process and provide the autoimmune-like pathogenic background. Moreover, Piezo2 channelopathy likely promotes diminishing HSF1 function in the hippocampus in the presence of the identified HSF1 variant. The current findings may support the ALS onsetting acquired irreversible Piezo2 channelopathy-induced pathogenesis. However, the preliminary nature of these findings needs validation and further functional studies on cohorts with a larger sample size in the future. Full article

Background and Clinical Significance: Idiopathic pulmonary arterial hypertension is a rare disorder, often linked to genetic predisposition. Canonical pulmonary arterial hypertension genes such as BMPR2, KCNK3, and TBX4 are well described, but novel associations continue to emerge. Glomulin (GLMN) encodes a protein essential for vascular smooth-muscle biology, classically implicated in glomuvenous malformations, yet not previously associated with pulmonary arterial hypertension. Case Presentation: We present a 49-year-old woman with progressive dyspnea, edema, and persistent hypercapnic respiratory failure. Right-heart catheterization confirmed precapillary pulmonary hypertension. Comprehensive evaluation, including ventilation/perfusion scanning, autoimmune panel, polysomnography, and high-resolution computed tomography, excluded secondary causes. Respiratory assessment revealed diaphragmatic weakness and reduced respiratory muscle pressures, consistent with primary myopathy and explaining the unusual hypercapnic profile. Whole-genome sequencing identified a heterozygous pathogenic GLMN nonsense variant, while canonical pulmonary arterial hypertension genes were negative. No cutaneous or mucosal glomuvenous malformations were found. The patient was treated with oxygen therapy, diuretics, non-invasive ventilation, and dual oral pulmonary arterial hypertension therapy (ambrisentan and tadalafil), with stabilization but persistent hypercapnia. Conclusions: To our knowledge, this is the first reported co-occurrence of idiopathic pulmonary arterial hypertension and a pathogenic GLMN variant. While causality cannot be inferred, glomulin’s role in vascular smooth-muscle maturation provides a plausible link to pulmonary vascular remodeling. This case underscores the importance of assessing respiratory muscle function in idiopathic pulmonary arterial hypertension patients with hypercapnia and highlights the potential relevance of extended genetic testing in rare pulmonary vascular disease. Full article

Background/Objectives: Platelet-derived growth factor receptor alpha (PDGFRα) is a receptor involved in cell growth and differentiation, with unclear roles in ovarian tissues and potential interactions with KCNK3 (potassium two-pore domain channel subfamily K member 3), a member of the two-pore domain K⁺ channel involved in cellular homeostasis. This study aims to map PDGFRα expression across mouse tissues and to explore its co-expression with KCNK3 in the ovary. Methods: We visualized PDGFRα expression using RNA-seq data from the genotype-tissue expression (GTEx) BodyMAP across 54 human tissues and Cap Analysis of Gene Expression (CAGE) data for various mouse tissues. In PDGFRα^EGFP mice expressing EGFP in PDGFRα⁺ cells, histological and fluorescence imaging were used to assess ovarian expression. Immunohistochemistry determined the co-localization of PDGFRα and KCNK3, and qPCR quantified their mRNA levels in the ovary, oviduct, and uterus. Results: PDGFRα showed high expression in human and mouse female reproductive tissues, particularly the ovary. In the PDGFRα^EGFP mouse model, PDGFRα was primarily found in the thecal layer and stromal cells, not in granulosa cells or oocytes. Immunohistochemistry indicated that 90.2 ± 8.7% of PDGFRα⁺ cells expressed KCNK3 in the ovarian stroma. qPCR revealed lower PDGFRα and KCNK3 expression in the ovary compared to the oviduct and uterus. Conclusions: This study shows that PDGFRα is predominantly expressed in ovarian stromal and theca cells and is highly co-localized with KCNK3, suggesting a potential role for PDGFRα⁺ cells in ionic regulation and their possible involvement in follicular development and ovarian physiology. Full article

This study investigated the effects of potassium magnesium sulfate (PMS) on intestinal dissociation and absorption rate, immune function, and expression of the NOD-like receptor thermal domain-associated protein 3 (NLRP3) inflammasome, aquaporins (AQPs), and potassium and magnesium ion channels in weaned piglets. Experiment 1 involved the assessment of the dissociation rate of PMS in pig digestive fluid and the absorption rate of PMS in the small intestine using an Ussing chamber in vitro. In Experiment 2, 216 healthy 21-day-old weaned piglets were selected and randomly assigned to six groups (0%, 0.15%, 0.30%, 0.45%, 0.60%, and 0.75% PMS), with each group 6 replicates of six piglets per replicate. The in vitro Ussing chamber results indicated that the absorption of K⁺ and Mg²⁺ in the jejunum and ileum was significantly higher than that in the duodenum (p < 0.05). The in vivo study demonstrated that the addition of PMS resulted in a linear increase in serum K⁺, IgG, and interleukin (IL)-2 levels while simultaneously reducing serum IL-1β levels (p < 0.05). Dietary PMS significantly elevated serum IL-10 and Mg²⁺ levels in feces (p < 0.05). Furthermore, supplementation with 0.60% or 0.75% PMS significantly downregulated the mRNA expression of NLRP3 in the jejunum (p < 0.05). Dietary PMS supplementation linearly reduced the mRNA expression levels of cysteine protease 1 (Caspase-1) and IL-1β in both the jejunum and colon as well as the mRNA expression levels of two-pore domain channel subfamily K member 5 (KCNK5) in these regions (p < 0.05). Notably, supplementation with 0.15% PMS significantly decreased the mRNA expression of transient receptor potential channel 6 (TRPM6) in the jejunum and significantly increased the expression of TRPM6 in the colon (p < 0.05). Dietary addition of 0.45% and 0.60% PMS significantly increased the mRNA expression of aquaporin 3 (AQP3) in the colon (p < 0.05), whereas 0.75% PMS significantly increased the mRNA expression of aquaporin 8 (AQP8) in both the jejunum and colon. Moreover, the expression levels of AQP3 and AQP8 were significantly negatively correlated with the diarrhea rate observed between days 29 and 42. In conclusion, dietary PMS supplementation improved immune function, inhibited the activation of intestinal NLRP3, and modulated the expression of water and ion channels in weaned piglets, thereby contributing to the maintenance of intestinal water and ion homeostasis, which could potentially alleviate post-weaning diarrhea in piglets. The recommended supplemental level of PMS in the corn-soybean basal diet for weaned piglets is 0.30%. Full article

The aim of this study was to identify genetic variants and pathways associated with the total number of piglets born and to investigate the potential negative consequences of the intensive selection for reproductive traits, particularly the formation of bumps on the legs of pigs. We used genome-wide association analysis and methods for identifying selection signatures. As a result, 47 SNPs were identified, localized in genes that play a significant role during sow pregnancy. These genes are involved in follicle growth and development (SGC), early embryonic development (CCDC3, LRRC8C, LRFN3, TNFRSF19), endometrial receptivity and implantation (NEBL), placentation, and embryonic development (ESRRG, GHRHR, TUSC3, NBAS). Several genes are associated with disorders of the nervous system and brain development (BCL11B, CDNF, ULK4, CC2D2A, KCNK2). Additionally, six SNPs are associated with the formation of bumps on the legs of pigs. These variants include intronic variants in the CCDC3, ULK4, and MINDY4 genes, as well as intergenic variants, regulatory region variants, and variants in the exons of non-coding transcripts. The results suggest important biological pathways and genetic variants associated with sow fertility and highlight the potential negative impacts on the health and physical condition of pigs. Full article

Clinical genomics sequencing is rapidly expanding the number of variants that need to be functionally elucidated. Interpreting genetic variants (i.e., mutations) usually begins by identifying how they affect protein-coding sequences. Still, the three-dimensional (3D) protein molecule is rarely considered for large-scale variant analysis, nor in analyses of how proteins interact with each other and their environment. We propose a standardized approach to scoring protein surface property changes as a new dimension for functionally and mechanistically interpreting genomic variants. Further, it directs hypothesis generation for functional genomics research to learn more about the encoded protein’s function. We developed a novel method leveraging 3D structures and time-dependent simulations to score and statistically evaluate protein surface property changes. We evaluated positive controls composed of eight thermophilic versus mesophilic orthologs and variants that experimentally change the protein’s solubility, which all showed large and statistically significant differences in charge distribution (p < 0.01). We scored static 3D structures and dynamic ensembles for 43 independent variants (23 pathogenic and 20 uninterpreted) across four proteins. Focusing on the potassium ion channel, KCNK9, the average local surface potential shifts were 0.41 k_BT/ec with an average p-value of 1 × 10⁻². In contrast, dynamic ensemble shifts averaged 1.15 k_BT/ec with an average p-value of 1 × 10⁻⁵, enabling the identification of changes far from mutated sites. This study demonstrates that an objective assessment of how mutations affect electrostatic distributions of protein surfaces can aid in interpreting genomic variants discovered through clinical genomic sequencing. Full article

Abstract: Our work aimed to evaluate and differentiate the role of ten lncRNA genes (GAS5, HAND2-AS1, KCNK15-AS1, MAGI2-AS3, MEG3, SEMA3B-AS1, SNHG6, SSTR5-AS1, ZEB1-AS1, and ZNF667-AS1) in the development and progression of epithelial ovarian cancer (EOC). A representative set of clinical samples was used: 140 primary tumors from patients without and with metastases and 59 peritoneal metastases. Using MS-qPCR, we demonstrated an increase in methylation levels of all ten lncRNA genes in tumors compared to normal tissues (p < 0.001). Using RT-qPCR, we showed downregulation and an inverse relationship between methylation and expression levels for ten lncRNAs (r_s < −0.5). We further identified lncRNA genes that were specifically hypermethylated in tumors from patients with metastases to lymph nodes (HAND2-AS1), peritoneum (KCNK15-AS1, MEG3, and SEMA3B-AS1), and greater omentum (MEG3, SEMA3B-AS1, and ZNF667-AS1). The same four lncRNA genes involved in peritoneal spread were associated with clinical stage and tumor extent (p < 0.001). Interestingly, we found a reversion from increase to decrease in the hypermethylation level of five metastasis-related lncRNA genes (MEG3, SEMA3B-AS1, SSTR5-AS1, ZEB1-AS1, and ZNF667-AS1) in 59 peritoneal metastases. This reversion may be associated with partial epithelial–mesenchymal transition (EMT) in metastatic cells, as indicated by a decrease in the level of the EMT marker, CDH1 mRNA (p < 0.01). Furthermore, novel mRNA targets and regulated miRNAs were predicted for a number of the studied lncRNAs using the NCBI GEO datasets and analyzed by RT-qPCR and transfection of SKOV3 and OVCAR3 cells. In addition, hypermethylation of SEMA3B-AS1, SSTR5-AS1, and ZNF667-AS1 genes was proposed as a marker for overall survival in patients with EOC. Full article

The TRESK (K2P18.1, KCNK18) background potassium channel is expressed in primary sensory neurons and has been reported to contribute to the regulation of pain sensations. In the present study, we examined the interaction of TRESK with NDFIP1 (Nedd4 family-interacting protein 1) in the Xenopus oocyte expression system by two-electrode voltage clamp and biochemical methods. We showed that the coexpression of NDFIP1 abolished the TRESK current under the condition where the other K⁺ channels were not affected. Mutations in the three PPxY motifs of NDFIP1, which are responsible for the interaction with the Nedd4 ubiquitin ligase, prevented a reduction in the TRESK current. Furthermore, the overexpression of a dominant-negative Nedd4 construct in the oocytes coexpressing TRESK with NDFIP1 partially reversed the down-modulating effect of the adaptor protein on the K⁺ current. The biochemical data were also consistent with the functional results. An interaction between epitope-tagged versions of TRESK and NDFIP1 was verified by co-immunoprecipitation experiments. The coexpression of NDFIP1 with TRESK induced the ubiquitination of the channel protein. Altogether, the results suggest that TRESK is directly controlled by and highly sensitive to the activation of the NDFIP1-Nedd4 system. The NDFIP1-mediated reduction in the TRESK component may induce depolarization, increase excitability, and attenuate the calcium dependence of the membrane potential by reducing the calcineurin-activated fraction in the ensemble background K⁺ current. Full article

The sodium-glucose co-transporter-2 (SGLT2) inhibitor dapagliflozin is increasingly used in the treatment of diabetes and heart failure. Dapagliflozin has been associated with reduced incidence of atrial fibrillation (AF) in clinical trials. We hypothesized that the favorable antiarrhythmic outcome of dapagliflozin use may be caused in part by previously unrecognized effects on atrial repolarizing potassium (K⁺) channels. This study was designed to assess direct pharmacological effects of dapagliflozin on cloned ion channels K_v11.1, K_v1.5, K_v4.3, K_ir2.1, K_2P2.1, K_2P3.1, and K_2P17.1, contributing to I_Kur, I_to, I_Kr, I_K1, and I_K2P K⁺ currents. Human channels coded by KCNH2, KCNA5, KCND3, KCNJ2, KCNK2, KCNK3, and KCNK17 were heterologously expressed in Xenopus laevis oocytes, and currents were recorded using the voltage clamp technique. Dapagliflozin (100 µM) reduced K_v11.1 and K_v1.5 currents, whereas K_ir2.1, K_2P2.1, and K_2P17.1 currents were enhanced. The drug did not significantly affect peak current amplitudes of K_v4.3 or K_2P3.1 K⁺ channels. Biophysical characterization did not reveal significant effects of dapagliflozin on current–voltage relationships of study channels. In conclusion, dapagliflozin exhibits direct functional interactions with human atrial K⁺ channels underlying I_Kur, I_Kr, I_K1, and I_K2P currents. Substantial activation of K_2P2.1 and K_2P17.1 currents could contribute to the beneficial antiarrhythmic outcome associated with the drug. Indirect or chronic effects remain to be investigated in vivo. Full article

Oxytocin, a significant pleiotropic neuropeptide, regulates psychological stress adaptation and social communication, as well as peripheral actions, such as uterine contraction and milk ejection. Recently, a Japanese Kampo medicine called Kamikihito (KKT) has been reported to stimulate oxytocin neurons to induce oxytocin secretion. Two-pore-domain potassium channels (K2P) regulate the resting potential of excitable cells, and their inhibition results in accelerated depolarization that elicits neuronal and endocrine cell activation. We assessed the effects of KKT and 14 of its components on a specific K2P, the potassium channel subfamily K member 2 (TREK-1), which is predominantly expressed in oxytocin neurons in the central nervous system (CNS). KKT inhibited the activity of TREK-1 induced via the channel activator ML335. Six of the 14 components of KKT inhibited TREK-1 activity. Additionally, we identified that 22 of the 41 compounds in the six components exhibited TREK-1 inhibitory effects. In summary, several compounds included in KKT partially activated oxytocin neurons by inhibiting TREK-1. The pharmacological effects of KKT, including antistress effects, may be partially mediated through the oxytocin pathway. Full article

The maintenance of plasma pH is critical for life in all organisms. The kidney plays a critical role in acid–base regulation in vertebrates by controlling the plasma concentration of bicarbonate. The receptor tyrosine kinase IRR (insulin receptor-related receptor) is expressed in renal β-intercalated cells and is involved in alkali sensing due to its ability to autophosphorylate under alkalization of extracellular medium (pH > 7.9). In mice with a knockout of the insrr gene, which encodes for IRR, urinary bicarbonate secretion in response to alkali loading is impaired. The specific regulatory mechanisms in the kidney that are under the control of IRR remain unknown. To address this issue, we analyzed and compared the kidney transcriptomes of wild-type and insrr knockout mice under basal or bicarbonate-loaded conditions. Transcriptomic analyses revealed a differential regulation of a number of genes in the kidney. Using TaqMan real-time PCR, we confirmed different expressions of the slc26a4, rps7, slc5a2, aqp6, plcd1, gapdh, rny3, kcnk5, slc6a6 and atp6v1g3 genes in IRR knockout mice. Also, we found that the expression of the kcnk5 gene is increased in wild-type mice after bicarbonate loading but not in knockout mice. Gene set enrichment analysis between the IRR knockout and wild-type samples identified that insrr knockout causes alterations in expression of genes related mostly to the ATP metabolic and electron transport chain processes. Full article

TWIK1 (K2P1.1/KCNK1) belongs to the potassium channels of the two-pore domain. Its current is very small and difficult to measure. In this work, we used a 100 mM NH₄⁺ extracellular solution to increase TWIK1 current in its stable cell line expressed in HEK293. Then, the inhibition of magnolol on TWIK1 was observed via a whole-cell patch clamp experiment, and it was found that magnolol had a significant inhibitory effect on TWIK1 (IC₅₀ = 6.21 ± 0.13 μM). By molecular docking and alanine scanning mutagenesis, the IC₅₀ of TWIK1 mutants G229A, T225A, I140A, L223A, and S224A was 20.77 ± 3.20, 21.81 ± 7.93, 10.22 ± 1.07, 9.55 ± 1.62, and 7.43 ± 3.20 μM, respectively. Thus, we conclude that the inhibition of the TWIK1 channel by magnolol is related to G229 and T225 on the P2- pore helix. Full article

Over a third of patients with temporal lobe epilepsy (TLE) are not effectively treated with current anti-seizure drugs, spurring the development of gene therapies. The injection of adeno-associated viral vectors (AAV) into the brain has been shown to be a safe and viable approach. However, to date, AAV expression of therapeutic genes has not been regulated. Moreover, a common property of antiepileptic drugs is a narrow therapeutic window between seizure control and side effects. Therefore, a long-term goal is to develop drug-inducible gene therapies that can be regulated by clinically relevant drugs. In this study, a first-generation doxycycline-regulated gene therapy that delivered an engineered version of the leak potassium channel Kcnk2 (TREK-M) was injected into the hippocampus of male rats. Rats were electrically stimulated until kindled. EEG was monitored 24/7. Electrical kindling revealed an important side effect, as even low expression of TREK M in the absence of doxycycline was sufficient to cause rats to develop spontaneous recurring seizures. Treating the epileptic rats with doxycycline successfully reduced spontaneous seizures. Localization studies of infected neurons suggest seizures were caused by expression in GABAergic inhibitory neurons. In contrast, doxycycline increased the expression of TREK-M in excitatory neurons, thereby reducing seizures through net inhibition of firing. These studies demonstrate that drug-inducible gene therapies are effective in reducing spontaneous seizures and highlight the importance of testing for side effects with pro-epileptic stressors such as electrical kindling. These studies also show the importance of evaluating the location and spread of AAV-based gene therapies in preclinical studies. Full article

The cardiac cell mechanical environment changes on a beat-by-beat basis as well as in the course of various cardiac diseases. Cells sense and respond to mechanical cues via specialized mechano-sensors initiating adaptive signaling cascades. With the aim of revealing new candidates underlying mechano-transduction relevant to cardiac diseases, we investigated mechano-sensitive ion channels (MSC) in human hearts for their chamber- and disease-preferential mRNA expression. Based on a meta-analysis of RNA sequencing studies, we compared the mRNA expression levels of MSC in human atrial and ventricular tissue samples from transplant donor hearts (no cardiac disease), and from patients in sinus rhythm (underlying diseases: heart failure, coronary artery disease, heart valve disease) or with atrial fibrillation. Our results suggest that a number of MSC genes are expressed chamber preferentially, e.g., CHRNE in the atria (compared to the ventricles), TRPV4 in the right atrium (compared to the left atrium), CACNA1B and KCNMB1 in the left atrium (compared to the right atrium), as well as KCNK2 and KCNJ2 in ventricles (compared to the atria). Furthermore, 15 MSC genes are differentially expressed in cardiac disease, out of which SCN9A (lower expressed in heart failure compared to donor tissue) and KCNQ5 (lower expressed in atrial fibrillation compared to sinus rhythm) show a more than twofold difference, indicative of possible functional relevance. Thus, we provide an overview of cardiac MSC mRNA expression in the four cardiac chambers from patients with different cardiac diseases. We suggest that the observed differences in MSC mRNA expression may identify candidates involved in altered mechano-transduction in the respective diseases. Full article