BK channels, coded by the Kcnma1 gene, integrate voltage and intracellular Ca2+ signals and are recognized for their roles in smooth muscle and neuronal excitability. However, their contribution to baseline cardiac physiology remains poorly defined. Here we uncover a fundamental function for BK channels in maintaining normal cardiac performance, independent of pathological stress. Using non-invasive echocardiography, transcriptional profiling, and mechanistic analyses, we demonstrate that Kcnma1 deletion disrupts ventricular function, and remodels metabolic and stress-response pathways. Transcriptomic profiling revealed selective downregulation of mitochondrial uncoupling proteins (UCPs) and suppression of the PGC-1α/FOXO3a axis, without broad loss of oxidative phosphorylation components. Enhancing UCP expression restored cardiac performance, indicating that mitochondrial uncoupling and redox control constitute key downstream effectors of BK signaling. Together, these results identify a physiological role for BK channels in maintaining myocardial function and define a mitochondrial BK-UCP axis, critical for cardiac homeostasis.

Background:Myocardial infarction (MI) triggers splenic immune cell trafficking to the heart. Vehicles that carry these signals and mediate this crosstalk are unknown. Hypothesis:We hypothesize that extracellular vesicles (EVs) released post-MI mediate splenic immune trafficking to the heart. Methods:Mice were treated daily with an EV biogenesis inhibitor (GW4869) or vehicle. Splenic/cardiac immune cells were assessed at 3d while survival, cardiac function, hypertrophy, and fibrosis were evaluated at 8w post-MI. Plasma EVs from 1d MI mice or from the hearts that underwent MI/sham in a Langendorff system induced splenic immune trafficking to the heart within 3d and systolic dysfunction at 8w in naïve mice. Results:GW4869 i) inhibited splenic regression, ii) increased splenic retention of neutrophils, monocytes, dendritic cells (DCs), and CD4+ T-cells, iii) decreased cardiac gene expression of proinflammatory cytokines/chemokines, and iv) decreased trafficking of immune cells to the hearts at 3d post-MI, and iii) improved systolic function and attenuated hypertrophy at 8w post-MI. MI EVs accumulated in the spleen and promoted egress of matured splenic immune cells upon administration to naïve mice. Cardiac pro-inflammatory cytokines/chemokines expression and CCR2+MHC-IIhi infiltrating macrophages, CD11c+ DCs, and CD4+ and CD4+TNFα+ T-cell levels were also increased in naïve mice at 3d post-injection. Importantly, transfer of MI EVs for 2 days induced systolic dysfunction, cellular hypertrophy, and fibrosis in naïve mice at 8 w post-injection. DCs process MI EVs for T-cells activation. Conclusions:EVs mobilize splenic immune cells to the heart post-MI and their inhibition can subdue inflammatory tissue-damage to promote healing post-MI.

Cystic fibrosis (CF) is a common genetic disease caused by a defective CF-transmembrane conductance regulator (CFTR). People with CF (pwCF) are prone to develop infections by opportunistic pathogens, including Burkholderia cenocepacia, leading to chronic inflammation. Neutrophils release granular proteins and oxidative products that contribute to tissue damage. CFTR modulators are a new treatment for pwCF aiming to correct the subcellular location and function of the CFTR ion channel. The triple modulator combination of Elexacaftor, Tezacaftor, and Ivacaftor (ETI) or Trikafta® has significantly improved clinical symptoms and overall provided a better quality of life for pwCF. The mechanism by which CFTR modulators help to restore the antimicrobial functions of neutrophils is unknown. The present study demonstrated that neutrophils functionally express CFTR and revealed how ETI modifies subcellular CFTR trafficking in CF neutrophils. In addition, ETI treatment reduced intracellular chloride levels in human neutrophils, indicating activation of CFTR-dependent chloride efflux. Finally, ETI treatment also re-established the intracellular antimicrobial killing of CF neutrophils by potentiating NADPH oxidase activity and improved trapping microbes by enhancing the production of Neutrophil Extracellular Traps (NETs). Together, our findings suggest that CFTR has an essential role in controlling neutrophil functions and CFTR modulators help restore the antimicrobial functions of neutrophils from pwCF.

Ion channels are critical regulators of cellular excitability, ionic homeostasis, and signal transduction, playing essential roles in cellular adaptation to hypoxic stress. Among these, intracellular chloride channels (CLICs) represent a unique subclass of chloride channels predominantly localized to intracellular organelles. Given their established roles in redox-regulation and transcriptional responsiveness to hypoxia, we investigated the hypoxic responses in Drosophila melanogaster, which possesses a single CLIC homolog. We subjected CLIC-null mutant flies to hypoxic stress and observed significantly enhanced resistance to hypoxia-induced damage compared to wild-type controls. Remarkably, acute hypoxic exposure followed by reoxygenation did not impair cardiac function in CLIC mutant flies, whereas wild-type flies exhibited notable cardiac dysfunction. Mutant flies also demonstrated improved overall survival under hypoxic conditions. To elucidate the underlying mechanisms of this protective phenotype, we assessed molecular markers and found consistent downregulation of ERK expression at the transcript, total protein, and phosphorylated levels in CLIC-mutant flies. Histological analysis revealed preserved myocardial fiber architecture in mutants, in contrast to the structural disarray observed in wild-type hearts. Furthermore, we detected upregulation of pro-survival signaling, particularly the AKT pathway, evidenced by increased AKT phosphorylation. This effect was abolished upon pharmacological inhibition with rapamycin. Collectively, our findings suggest that Drosophila CLIC proteins contribute to maladaptive cardiac remodeling and suppression of cytoprotective signaling under hypoxic stress. Inhibition of CLIC function appears to confer cardioprotection and enhance organismal survival in hypoxic environments, highlighting a potential therapeutic target for ischemic heart disease.

The human long noncoding RNA (lncRNA) RMRP , initially identified as part of the RNase MRP complex, is linked to various human diseases. However, its structural flexibility and broader cellular roles are not well understood. Here, we offer a comprehensive analysis of RMRP ’s structure in solution, its interactions with human proteins, and its mitochondrial functions. Using small-angle X-ray scattering (SAXS), we show that RMRP adopts different Mg 2+ -dependent shapes, shifting from an extended Y-shaped form to a more compact one as Mg 2+ levels increase. We identified and characterized interactions between RMRP and the DEAD-box RNA helicases DDX5 and DDX3X, with DDX5 binding strongly and exhibiting ATP-dependent helicase activity on RMRP , while DDX3X mainly acts as an expression regulator. Both helicases are crucial for the proper mitochondrial localization of RMRP , working within a complex regulatory network. Functionally, reducing RMRP levels disrupts mitochondrial stability, leading to membrane depolarization and an increase in reactive oxygen species, without affecting cell growth. Mechanistically, RMRP specifically controls nuclear-encoded mitochondrial proteins involved in cristae structure (DNAJC11) and respiratory chain function (NDUFS8). Our results position RMRP as a structurally adaptable lncRNA that collaborates with RNA helicases to preserve mitochondrial health through specific gene regulation. These insights provide perspectives on RMRP ’s biology and the molecular mechanisms underlying RMRP -related disorders, which could inform future therapies for conditions resulting from RMRP dysfunction.

Pseudomonas aeruginosa is a gram-negative, opportunistic pathogen and a major cause of severe pneumonia. Healthcare-associated pneumonia accounts for up to 22% of all healthcare-acquired infections, with P. aeruginosa contributing to approximately 10-20% of these cases. Infections caused by P. aeruginosa carry a high mortality rate, ranging from 32% to 42.8%. Notably, the risk of pneumonia is strongly associated with cardiovascular diseases (CVD), particularly heart failure, independent of age, sex, comorbidities, or antibiotic usage. Individuals with CVD are at increased risk of developing both hospital-acquired pneumonia (HAP) and community-acquired pneumonia (CAP). Despite this association, the mechanisms underlying infection-induced cardiac dysfunction remain poorly understood. In our previous studies, we demonstrated that P. aeruginosa lung infection leads to severe cardiac electrical disturbances, including arrhythmias and left ventricular (LV) dysfunction, despite minimal bacterial dissemination to the heart. To further elucidate the mechanisms of P. aeruginosa-induced cardiac dysfunction, we employed both in vitro and in vivo infection models. Exposure of human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) to conditioned media from P. aeruginosa-infected human macrophages (hMDMs) resulted in profound contractile dysfunction in the hiPSC-CMs. We identified vesicles released from infected hMDMs along with bacterial outer membrane vesicles (OMVs) as key mediators of this dysfunction. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), we identified bacterial proteins, including toxins, packaged within both exosomes and OMVs that were responsible for the cardiotoxic effects. Moreover, systemic administration of bacterial OMVs in mice led to severe cardiac dysfunction. In summary, our findings indicate that during P. aeruginosa infection, bacterial OMVs are released into circulation and play a central role in mediating cardiac dysfunction.IMPORTANCEBacterial pneumonia can lead to severe cardiovascular complications and is a major contributor to increased mortality among hospitalized patients, either directly or indirectly. Pseudomonas aeruginosa, an opportunistic pathogen frequently encountered in hospital settings, accounts for nearly 20% of all infections in intensive care units (ICUs). Our previous studies demonstrated that P. aeruginosa lung infection induces profound cardiac electrical abnormalities and left ventricular (LV) dysfunction, despite minimal bacterial dissemination to the heart. In the present study, we identify exosomes released from infected host cells and outer membrane vesicles (OMVs) secreted by P. aeruginosa as critical mediators of this cardiac dysfunction. We show that host-derived exosomes are enriched with bacterial OMVs containing toxins and other immunogenic molecules, which promote systemic inflammation and tissue injury, ultimately contributing to cardiac impairment.

BackgroundChloride ions (Cl) regulate sperm physiology, influencing spermatogenesis, volume regulation, capacitation, and fertilization processes. They contribute to the maintenance of membrane potential and intracellular pH, both of which are critical for sperm motility and capacitation. Any deviation in Cl homeostasis causes impaired sperm function and male infertility. Although several Cl channels and transporters have been implicated in the Cl homeostasis and osmoregulation of sperm cells, the precise mechanisms and molecular components governing volume regulation during sperm development remain unclear.MethodsWe used a combination of electrophysiological recordings via the patch-clamp technique and biochemical analyses, including western blotting and immunocytochemistry, to demonstrate the functional expression of a novel chloride channel, Chloride Intracellular Channel 4 (CLIC4), in the plasma membrane of sperm cells. To assess physiological roles, we analyzed sperm cells from wild type and null mutant mice (clic4-/-), measuring motility, morphology and acrosome reaction.ResultsWe identified previously uncharacterized IAA-94-sensitive chloride currents in mouse sperm cells. Genetic ablation of CLIC4 eliminated these IAA-94-sensitive currents. Notably, CLIC4 regulates cell volume during sperm maturation without altering membrane potential, motility, or the acrosome reaction. CLIC4 activity in sperm cells is modulated by Protein Kinase C (PKC).ConclusionCLIC4 is a key component of the sperm cell volume regulation machinery, modulating Cl fluxes during maturation. These findings provide new insights into the molecular basis of sperm osmoregulation and may inform therapeutic strategies for male infertility.

Heart failure with preserved ejection fraction (HFpEF) accounts for nearly half of all heart failure cases. In addition to diastolic dysfunction, patients with HFpEF have a substantial risk of sudden cardiac death, suggesting a potential contribution of malignant ventricular arrhythmias. Recently, small conductance Ca2+-activated K+ (SK) channels have emerged as potential modulators of mitochondria-dependent production of harmful reactive oxygen species (ROS). This study aimed to evaluate SK channel enhancement as a novel strategy to reverse proarrhythmic changes in intracellular Ca2+ cycling and in mitochondrial redox and Ca2+ homeostasis in ventricular myocytes using obese ZSF1 rat model of HFpEF. Confocal imaging of Ca2+ and ROS was performed in ventricular myocytes isolated from lean and obese ZSF1 rats. Mitochondrial matrix Ca2+ and ROS levels were measured using matrix-targeted biosensors mtRCamp1h and MLS-HyPer7, respectively. SK channel activity was enhanced by adenoviral overexpression of rat SK channel type 2 and by pharmacological activators NS309 and Riluzole. Ventricular myocytes from obese ZSF1 rats, when periodically paced and exposed to the β-adrenergic agonist isoproterenol, showed increased pro-arrhythmic diastolic sarcoplasmic reticulum (SR) Ca2+ release, elevated mitochondrial ROS production, and marked mitochondrial Ca2+ overload. SK channel enhancement prevented mitochondrial Ca2+ overload, reduced ROS emission, and improved cytosolic Ca2+ cycling by suppressing diastolic SR Ca2+ release These findings identify SK channel activation as a potential antiarrhythmic therapeutic strategy in HFpEF by limiting mitochondrial Ca2+ uptake, reducing oxidative stress and stabilizing intracellular Ca2+ dynamics.

Extracellular vesicles (EVs) are a heterogeneous population of lipid bilayer-enclosed particles secreted by nearly all cell types into the extracellular milieu. Once considered cellular debris, EVs are now recognized as biologically active entities capable of transferring proteins, lipids, and nucleic acids to recipient cells, thereby modulating their function and contributing to intercellular communication. EVs play pivotal roles in immune regulation, signal transduction, and antigen presentation. EV molecular cargo reflects the physiological or pathological state of the parent cell, offering potential as diagnostic and prognostic biomarkers in a range of diseases, including cancer, neurodegeneration, and cardiovascular disorders. Traditionally, EVs have been classified into exosomes, microvesicles, and apoptotic bodies based on their size and biogenesis. Recent discoveries have expanded this taxonomy to include novel subtypes with distinct biophysical and molecular characteristics. This review focuses on EVs, with an emphasis on their biogenesis, mechanisms of ionic balance and homeostasis, and the presence and function of ion channels and transporters. We also highlight current methodologies for detecting functional ion channels within exosomes, underscoring their emerging significance in cellular physiology and disease pathogenesis.

Oncostatin M receptor (OSMR) plays diverse roles in several human malignancies, including brain, breast, and pancreatic cancer. In glioblastoma (GB), OSMR orchestrates a feedforward signaling mechanism with the truncated active mutant of epidermal growth factor receptor (EGFR), the EGFRvIII, and signal transducer and activator of transcription 3 (STAT3) to drive GB progression. Beyond EGFRvIII, OSMR promotes brain tumor stem cell (BTSC) respiration and therapy resistance. The molecular mechanisms underlying OSMR’s multifaceted roles remain largely unclear. Here, we systematically mapped the OSMR interactome using Mammalian Membrane Two-Hybrid High-Throughput Screening (MaMTH-HTS). We identified OSMR-specific and OSMR/EGFRvIII-specific high-confidence candidate binding proteins, highlighting OSMR context-dependent functions. Among a subset of common interactors, we uncovered chloride intracellular channel 1 (CLIC1) as a critical regulator of OSMR-STAT3 signaling and the OSMR/EGFRvIII complex. CLIC1 physically associates with OSMR and EGFRvIII and facilitates EGFRvIII packaging into extracellular vesicles (EVs). Genetic deletion of CLIC1 disrupts the OSMR/EGFRvIII interaction, impairs STAT3 activation, reduces EGFRvIII EV content, and slows GB progression. Using whole-cell patch-clamp recordings and a monoclonal antibody that selectively targets transmembrane CLIC1 (tmCLIC1omab), we establish a distinct pharmacologically and biophysically tmCLIC1-mediated current in GB indispensable for sustaining EGFRvIII/STAT3 signaling. Importantly, we show that OSMR is required for maintaining CLIC1-mediated ionic balance at the plasma membrane (PM). Our study uncovers a bidirectional crosstalk between OSMR and tmCLIC1 in GB, essential for fueling its malignant growth.

Micro- and nanoplastics (MNPs) and the tire-derived transformation product 6-PPD-Quinone (6-PPD-Q) have emerged as pervasive environmental pollutants with critical implications for cardiopulmonary health and ecosystem integrity. This review identifies tire wear particles (TWPs) as a primary source of both airborne and waterborne MNPs, as well as 6-PPD, which readily oxidizes into the highly toxic 6-PPD-Q. These contaminants have been detected across diverse environmental compartments including air, soil, water, and remote ecosystems highlighting their global distribution and persistence. Human exposure occurs primarily through inhalation, ingestion, and dermal contact. Although mechanistic studies remain limited, available evidence indicates that MNPs and 6-PPD-Q induce oxidative stress, inflammation, mitochondrial dysfunction, apoptosis, and endothelial damage, particularly in pulmonary and cardiovascular tissues. Their detection in human tissues and excreta raises urgent public health concerns. Beyond human health, these toxicants adversely affect soil microbial communities, aquatic organisms, and crop productivity, underscoring their broader ecological footprint within a One Health framework. Regulatory oversight remains limited, especially for nanoplastics and tire-derived compounds, emphasizing the need for standardized detection methods and globally coordinated research and policy initiatives. This review underscores the urgency of implementing comprehensive mitigation strategies, including environmental monitoring, occupational safeguards, and public education, to address the growing threat posed by TWPs, MNPs, and 6-PPD-Q.

Chloride intracellular ion channels (CLICs) represent a relatively underexplored class of chloride channels and are included in a research initiative that focuses on druggable genes that have not been well studied yet. As a unique family, CLICs exist in membrane and soluble forms and play a role in regulating chloride flux and modulating various aspects of cellular biology. To date, six mammalian CLICs have been cloned and characterized at molecular and physiological levels. The respiratory system, responsible for gas exchange between the atmosphere and the human body, has recently been shown to express CLICs with functional relevance in lung pathophysiology, including lung carcinoma, inflammation, and endothelial dysfunction. Notably, the expression patterns of CLIC isoforms in lung cell types are distinct. Among them, CLIC1, CLIC3, and CLIC4 have been investigated more extensively, particularly in the context of lung cancer, inflammatory diseases, and pulmonary arterial hypertension. A deeper understanding of the role of CLICs in regulating lung cellular function may pave the way for developing novel therapeutic strategies to treat pulmonary disorders. In this review, we summarize the expression and functional roles of CLICs in lung pathophysiology, with particular emphasis on CLIC1, CLIC3, and CLIC4.

Dimorphic ion channels, chloride intracellular ion channels (CLIC), are known to regulate several cellular processes, but their implication in cardiac physiology remains unclear. Artificial planar lipid bilayer studies have shown that CLIC2 negatively modulates the activity of cardiac ryanodine receptor 2 (RyR2), implicating the sarcoplasmic/endoplasmic reticulum (SR/ER) Ca 2+ release. In heart failure, RyR2 channel activity is altered causing aberrant SR Ca 2+ release, depletion of SR Ca 2+ stores, and reduced myocardial contractility in heart failure. Hence, the characterization of intrinsic RyR2 modulators will represent a novel target for the prevention and treatment of heart failure. Moreover, CLIC2 protein expression is significantly increased (p<0.05) in end-stage failing human heart samples compared to non-failing heart tissues. Hence using human induced pluripotent stem cells derived cardiomyocytes (hiPSC-CM), we assessed the contribution of CLIC2 in the regulation of cellular Ca 2+ homeostasis in cardiac physiology. CLIC2 knockout hiPSC-CM (CLIC2KO-CMs) showed altered electrophysiological properties, where the beat period (0.686±0.018 sec) and field potential duration (134.266±9.07 ms) decreased as compared to age-matched WT hiPSC-CM (WT-CMs) (0.760±0.014sec and 215.37±7.82ms, respectively). Similarly, spike amplitude showed a decrease in CLIC2KO-CMs (0.339 ± 0.046 mV) compared to WT-CMs (0.705±0.069 mV). Moreover, the APD30, APD50, and APD90 in CLIC2KO-CMs (0.109±0.013, 0.132±0.011, 0.186±0.008 sec respectively) were significantly reduced as compared to the WT-CMs (0.173±0.005, 0.204±0.008, 0.264±0.008 sec respectively). Furthermore, the intracellular Ca 2+ measurements revealed an altered Ca 2+ handling in CLIC2KO-CMs, where a decrease in peak amplitude (3.35±0.13) and duration (1179±9.52 ms) was observed compared to the WT-CMs (5.87±0.25 and 3081.38±55.95 ms, respectively). Finally, the caffeine-sensitive Ca 2+ store load in CLIC2KO-CMs showed a marked reduction in cytosolic caffeine transient amplitude, suggesting an increased SR-Ca 2+ leak due to hyperactive RyR2 channels. Overall, our study highlights CLIC2 as an understudied negative modulator of RyR2 involved in the SR/ER Ca 2+ release mechanism that is upregulated in failing human hearts.

Extracellular vesicles (EVs) are associated with intercellular communications, immune responses, viral pathogenicity, cardiovascular diseases, neurological disorders, and cancer progression. EVs deliver proteins, metabolites, and nucleic acids into recipient cells to effectively alter their physiological and biological response. During their transportation from the donor to the recipient cell EVs face differential ionic concentrations, which can be detrimental to their integrity and impact their cargo content. EVs are known to possess ion channels and transporters in their membrane but neither the function nor the role of these channels in EVs is known. In this study, we discover a functional calcium-activated large-conductance potassium channel (BKCa) in the membrane of EVs. Furthermore, we establish that BKCa is essential for the structural and functional integrity of EVs. Together, these findings establish the critical role of ion channels such as BKCa in functioning as gatekeepers and maintaining EV-mediated signaling.

The mitochondrion-endoplasmic reticulum (ER) contact sites (MERCs, also known as mitochondrial-associated membranes [MAMs]) are specialized regions of the ER that are in close proximity to the mitochondrion. These organelle structures play essential roles in a variety of processes, such as calcium signaling, lipid metabolism, renin-angiotensin-aldosterone system control, the unfolded protein response, and autophagy. MERCs are known to actively participate in ion transport between the ER and mitochondria. Although active calcium channels in MERCs have been detected, limited studies have been carried out to identify or characterize functional anion channels. Here, we tested whether functional anion channels are present in MERCs. We isolated MERCs from mouse organs (heart and brain) and reconstituted them in planar bilayers. The single-channel properties were recorded in the presence of various anion channel blockers or antagonists (IAA-94, DIDS, A9C, and NPPB). We corroborated the presence of anion channels targeted by these drugs using immunoblotting and immunocytochemistry. Biochemical analysis and immunocytochemistry corroborate that CLIC4, CLIC3, and VDACs are present in MERCs. Our results indicate that anion channels are active in MERCs, which could play a pertinent role in intracellular organelle communication.