Fluo-3 Fluorescence Research Articles

Zeatin Elicits Premature Erythrocyte Senescence Through Calcium and Oxidative Stress Mediated by the NOS/PKC/CK1α Signaling Axis.

Objectives: Cytokinins are plant hormones that regulate cell growth and differentiation. In particular, zeatin (ZTN) delays cellular senescence of human fibroblasts and keratinocytes and exhibits anticancer activity. Chemotherapy-induced anemia is a major side effect of anticancer therapy secondary to premature senescence of red blood cells (RBCs). Herein, we investigated the biochemical and molecular mechanisms underlying ZTN action in human RBCs. Methods: Colorimetric assays were used to quantify hemolysis and related markers and flow cytometric analysis was applied to examine eryptosis through phosphatidylserine (PS) exposure by annexin-V-FITC, intracellular Ca2+ by Fluo4/AM, reactive oxygen species (ROS) by H2DCFDA, and cell size from forward scatter (FSC). Results: ZTN at 200μM induced significant hemolysis and K+, Na+, AST, and LDH leakage. ZTN also caused a significant increase in annexin-V-positive cells along with increased Fluo4 and DCF fluorescence and reduced FSC. Importantly, L-NAME, staurosporin, D4476, urea, sucrose, and polyethylene glycol 8000 (PEG) significantly ameliorated ZTN cytotoxicity. Conclusion: ZTN stimulates PS exposure, intracellular Ca2+ elevation, oxidative stress, and cell shrinkage. The hemolytic potential of ZTN, mediated through nitric oxide synthase/protein kinase C/casein kinase 1α signaling axis, is sensitive to isosmotic urea, sucrose, and PEG availability. Altogether, the anticancer potential of ZTN must be reconsidered with prudence.

Galangin Triggers Eryptosis and Hemolysis Through Ca2+ Nucleation and Metabolic Collapse Mediated by PKC/CK1α/COX/p38/Rac1 Signaling Axis.

Anticancer drugs cause anemia in patients through eryptosis and hemolysis. We thus studied the in vitro toxicity of galangin (GAL) in red blood cells (RBCs). RBCs were exposed to 50-500 μM of GAL and analyzed for markers of eryptosis and hemolysis. Ca2+ nucleation, phosphatidylserine (PS) externalization, oxidative stress, and cell size were detected via fluorescence-activated cell sorting using Fluo4/AM, annexin-V-FITC, 2',7'-dichlorodihydrofluorescein diacetate, and forward scatter (FSC), respectively. Acetylcholinesterase (AChE) activity was measured via Ellman's assay and ultrastructural morphology was examined via scanning electron microscopy. Membrane rupture and extracellular hemoglobin, aspartate transaminase (AST), and lactate dehydrogenase (LDH) were assessed via colorimetric methods. Distinct experiments were carried out to identify protective agents and signaling pathways using small-molecule inhibitors. GAL triggered sucrose-sensitive hemolysis with AST and LDH leakage, increased annexin-V-FITC and Fluo4 fluorescence, and decreased FSC and AChE activity which was associated with the formation of granulated echinocytes. Ca2+ omission and energy replenishment with glucose, adenine, and guanosine blunted PS externalization and preserved cellular volume. Moreover, caffeine, Trolox, heparin, and uric acid had similar ameliorative effects. Hemolysis was abrogated via caffeine, Trolox, heparin, mannitol, lactate, melatonin, and PEG 8000. Notably, co-treatment of cells with GAL and staurosporin, D4476, or acetylsalicylic acid prevented PS externalization whereas only the presence of SB203580 and NSC23766 rescued the cells from GAL-induced hemolysis. Ca2+ nucleation and metabolic collapse mediated by PKC/CK1α/COX/p38/Rac1 drive GAL-induced eryptosis and hemolysis. These novel findings carry ramifications for the clinical prospects of GAL in anticancer therapy.

Linolenic acid stimulates eryptosis and hemolysis through oxidative stress and CK1α/MLKL: protective role of melatonin, urea, and polyethylene glycol

Anticancer medications cause anemia in patients through ill-defined mechanisms, including hemolysis and eryptosis. Although α-linolenic acid (ALA) possesses anticancer properties against a variety of cancer cells, there is a dearth of evidence regarding how it modulates red blood cell (RBC) physiology. RBCs from healthy donors were subjected to anticancer concentrations of ALA (2.5, 5, 10, 20, 40, 80, and 100 μM) at 37 °C for 24 h, and colorimetric tests were used to determine hemolysis and acetylcholinesterase (AChE) activity. Meanwhile, flow cytometry was employed to identify eryptotic cells using annexin-V-FITC and forward scatter (FSC), Fluo4/AM to detect Ca2+, and H2DCFDA to assess oxidative stress. ALA significantly increased hemolysis and eryptosis in a concentration-dependent manner, along with elevated Fluo4 and DCF fluorescence, and erythrocyte sedimentation rate, and reduced FSC and AChE activity. Moreover, the addition of D4476, necrosulfonamide, melatonin, isosmotic urea, and polyethylene glycol 8000 – but not sucrose – significantly inhibited ALA toxicity. In conclusion, ALA stimulates hemolysis and eryptosis through Ca2+ buildup, oxidative stress, anticholinesterase activity, casein kinase 1α (CK1α), and mixed lineage kinase domain-like protein (MLKL). The anticancer activity of ALA may be potentiated by the use of Ca2+ channel blockers and chelators, antioxidants, and CK1α and MLKL inhibitors to ameliorate its toxicity to RBCs.

Identification and characterisation of functional Kir6.1-containing ATP-sensitive potassium channels in the cardiac ventricular sarcolemmal membrane.

The canonical Kir6.2/SUR2A ventricular KATP channel is highly ATP-sensitive and remains closed under normal physiological conditions. These channels activate only when prolonged metabolic compromise causes significant ATP depletion and then shortens the action potential to reduce contractile activity. Pharmacological activation of KATP channels is cardioprotective, but physiologically, it is difficult to understand how these channels protect the heart if they only open under extreme metabolic stress. The presence of a second KATP channel population could help explain this. Here, we characterise the biophysical and pharmacological behaviours of a constitutively active Kir6.1-containing KATP channel in ventricular cardiomyocytes. Patch-clamp recordings from rat ventricular myocytes in combination with well-defined pharmacological modulators was used to characterise these newly identified K+ channels. Action potential recording, calcium (Fluo-4) fluorescence measurements and video edge detection of contractile function were used to assess functional consequences of channel modulation. Our data show a ventricular K+ conductance whose biophysical characteristics and response to pharmacological modulation were consistent with Kir6.1-containing channels. These Kir6.1-containing channels lack the ATP-sensitivity of the canonical channels and are constitutively active. We conclude there are two functionally distinct populations of ventricular KATP channels: constitutively active Kir6.1-containing channels that play an important role in fine-tuning the action potential and Kir6.2/SUR2A channels that activate with prolonged ischaemia to impart late-stage protection against catastrophic ATP depletion. Further research is required to determine whether Kir6.1 is an overlooked target in Comprehensive in vitro Proarrhythmia Assay (CiPA) cardiac safety screens.

ELD607 specifically traffics Orai1 to the lysosome leading to inhibition of store operated calcium entry

Orai1 is a plasma membrane Ca2+ channel involved in store operated calcium entry (SOCE). SOCE can regulate cell growth, exocytosis, gene expression and inflammation. We previously found that short palate lung and nasal epithelial clone 1′s (SPLUNC1) sixth α-helix (α6) bound Orai1 to inhibit SOCE. SPLUNC1 was not proteolytically stable, so we developed ELD607, an 11 amino acid peptide based on SPLUNC1’s α6 region which was more stable and more potent than SPLUNC1/α6. Here, we studied ELD607’s mechanism of action. We overexpressed either Orai1-HA or Orai1-YFP in HEK293T cells to probe ELD607-Orai1 interactions by confocal microscopy. We also measured changes in Fluo-4 fluorescence in a multiplate reader as a marker of cytoplasmic Ca2+ levels. ELD607 internalized Orai1 independently of STIM1. Both 15 min and 3 h exposure to ELD607 similarly depleted Orai1 in the plasma membrane. However, 3 h exposure to ELD607 yielded greater inhibition of SOCE. ELD607 continued to colocalize with Orai1 after internalization and this process was dependent on the presence of the ubiquitin ligase NEDD4.2. Similarly, ELD607 increased the colocalization between Orai1 and ubiquitin. ELD607 also increased the colocalization between Orai1 and Rab5 and 7, but not Rab11, suggesting that Orai1 trafficked through early and late but not recycling endosomes. Finally, ELD607 caused Orai1, but not Orai2, Orai3, or STIM1 to traffic to lysosomes. We conclude that ELD607 rapidly binds to Orai1 and works in an identical fashion as full length SPLUNC1 by internalizing Orai1 and sending it to lysosomes, leading to a decrease in SOCE.

Sertraline Alleviates Chronic Prostatitis by Regulating the TRPV1 Channel.

Although sertraline has been widely used for chronic prostatitis (CP), the mechanisms are unclear. Herein, we explored the mechanisms of sertraline in treating CP. Network pharmacology methods were used to explore the potential targets and molecular mechanisms. LPS was used to stimulate RWPE-1 cells to construct an in vitro model of CP. An experimental autoimmune prostatitis (EAP) mice model was built. CCK-8 assay, EdU assay, BrdU detection, and Tunel assay were performed to evaluate the proliferation and apoptosis process of cells or tissues, respectively. DCFH-DA and Fluo-4 fluorescence probes were used to detect intracellular ROS and calcium concentrations. Von Frey filaments and open-field tests were utilized to evaluate pain response and depressive-like behavior of mice. Histopathology was evaluated through hematoxylin and eosin staining. RT-qPCR, Western blot, immunofluorescence, and immunohistochemistry were utilized to evaluate the transcription, expression, and location of related proteins. Molecular dynamics (MD) simulation and surface plasmon resonance (SPR) assay were performed to measure the binding capacity of sertraline and related proteins. Through a network pharmacology analysis, 27 potential targets of sertraline for CP were obtained, and 5 key targets (CHRM1, ADRA1B, HTR2B, HTR2A, and TRPV1) were finally identified. Functional experiments suggested that TRPV1 was involved in the proliferation, apoptosis inhibition, and ROS production of LPS-induced RWPE-1 cells. In vitro experiments showed that sertraline significantly inhibited cell proliferation, ROS generation, and transcription of inflammation cytokines of LPS-induced RWPE-1 cells. Additionally, sertraline markedly promoted the apoptosis level of LPS-stimulated RWPE-1 cells and elevated the expression level of BAX while reducing the expression levels of Bcl2 and Caspase-3. MD simulation and SPR assay confirmed the direct binding of sertraline to TRPV1. Moreover, sertraline significantly down-regulated the expression level of TRPV1 and inhibited calcium influx of LPS-induced RWPE-1 cells. TRPV1 agonist (Capsaicin) significantly restored the effects on proliferation, apoptosis, ROS production, and calcium influx of sertraline on LPS-induced RWPE-1 cells. Mice experiments demonstrated that sertraline treatment could reduce pain response, improve depression-like symptoms, and relieve local prostate inflammation of EAP mice, as well as down-regulated the expression level of TRPV1, inhibit the proliferation, and promote apoptosis of prostate tissues in EAP mice. The results revealed the anti-inflammatory effect of sertraline for RWPE-1 cells and EAP mice, and the potential mechanism was regulating the TRPV1 channel. It indicated that sertraline might serve as a complementary anti-inflammatory agent for CP.

FOXD2 regulations IQGAP3 mediated Ca2+ signaling pathway to facilitate gastric adenocarcinoma cell promotion.

As a transcriptional factor, the Forkhead box (FOX) gene family is closely connected with apoptosis, proliferation, and other cellular processes. FOXD2, as one descendant of the FOX gene family, has been mentioned in many articles to show a high expression in several cancers. However, whether FOXD2 has a connection with gastric adenocarcinoma remains an unanswered question. Expression of FOXD2 and IQGAP3 in gastric adenocarcinoma was evaluated by bioinformatics analysis, which was further detected by real-time quantitative PCR (qRT-PCR) and western blot. The downstream target genes of FOXD2 were also mined by bioinformatics analysis. Pathway enrichment analysis was then performed on the target genes. Chromatin immunoprecipitation assay (ChIP) and dual-luciferase reporter assay were conducted to validate the regulatory relationship between FOXD2 and its downstream target gene IQGAP3. Methyl thiazolyl tetrazolium assay (MTT), combined with cell colony formation assay, was employed to assess the effect of FOXD2 and IQGAP3 on the proliferation of gastric adenocarcinoma cells. Intracytoplasmic Ca2+ concentration was measured by Fluo-3 fluorescence staining. FOXD2 showed a high expression in gastric adenocarcinoma tissues and cells, and FOXD2 silencing considerably attenuated gastric adenocarcinoma cell proliferation. IQGAP3, a downstream target gene of FOXD2, had a positive connection with the expression of FOXD2. The binding relationship between FOXD2 and the promoter region of IQGAP3 was further verified by ChIP and dual-luciferase reporter assays. The results of cell function experiments indicated that FOXD2 could promote gastric adenocarcinoma cell proliferation by transcriptionally activating IQGAP3 to induce an increase in intracellular Ca2+ level. This study confirmed that FOXD2 increased intracellular Ca2+ level through transcriptional activation of IQGAP3, which in turn propelled the proliferation of gastric adenocarcinoma cells, revealing the considerable significance of FOXD2 in the development of gastric adenocarcinoma.

Antrodin C Isolated from Antrodia Cinnamomea Induced Apoptosis through ROS/AKT/ERK/P38 Signaling Pathway and Epigenetic Histone Acetylation of TNFα in Colorectal Cancer Cells.

Antrodin C, a maleimide derivative compound isolated from the ethanol extract of the mycelium of Antrodia cinnamomea, is an endemic fungus of Taiwan and a potential chemoprotective agent. However, the molecular mechanisms underlying the mode of action of antrodin C on cancer cells, especially in human colorectal cancer (CRC), remain unclear. The cell death and ROS of the antrodin-C-treated HCT-116 cells were measured by annexin V-FITC/propidium iodide staining, DCFDA, and Fluo-3 fluorescence staining assays. Moreover, signaling molecules regulating TNFα cell death pathways and ROS/AKT/ERK/P38 pathways were also detected in cells treated with antrodin C by Western blotting and chromatin immunoprecipitation. The effects of antrodin C were determined in HCT-116 cell xenograft animal models in terms of tumor volumes and histopathological evaluation. Treatment with antrodin C triggered the activation of extrinsic apoptosis pathways (TNFα, Bax, caspase-3, and -9), and also suppressed the expression of anti-apoptotic molecules Bcl-2 in HCT-116 cells in a time-dependent manner. Antrodin C also decreased cell proliferation and growth through the inactivation of cyclin D1/cyclin for the arrest of the cell cycle at the G1 phase. The activation of the ROS/AKT/ERK/P38 pathways was involved in antrodin-C-induced transcriptional activation, which implicates the role of the histone H3K9K14ac (Acetyl Lys9/Lys14) of the TNFα promoters. Immunohistochemical analyses revealed that antrodin C treatment significantly induced TNFα levels, whereas it decreased the levels of PCNA, cyclin D1, cyclin E, and MMP-9 in an in vivo xenograft mouse model. Thus, antrodin C induces cell apoptosis via the activation of the ROS/AKT/ERK/P38 signaling modules, indicating a new mechanism for antrodin C to treat CRC in vitro and in vivo.

Myricetin-induced suicidal erythrocyte death.

Myricetin, a type of flavonol commonly found in fruits and herbs, has demonstrated anticancer properties by triggering the process of apoptosis or programmed cell death in tumor cells. Despite the absence of mitochondria and nuclei, erythrocytes can undergo programmed cell death, also known as eryptosis.This process is characterized by cell shrinkage, externalization of phosphatidylserine (PS) on the cell membrane, and the formation of membrane blebs. The signaling of eryptosis involves Ca2+ influx, the formation of reactive oxygen species (ROS), and the accumulation of cell surface ceramide. The present study explored the effects of myricetin on eryptosis. Human erythrocytes were exposed to various concentrations of myricetin (2-8 µM) for 24h. Flow cytometry was used to assess the markers of eryptosis, including PS exposure, cellular volume, cytosolic Ca2+ concentration, and ceramide accumulation. In addition, the levels of intracellular ROS were measured using the 2',7'-dichlorofluorescin diacetate (DCFDA) assay. The myricetin-treated (8 µM) erythrocytes significantly increased Annexin-positive cells, Fluo-3 fluorescence intensity, DCF fluorescence intensity, and the accumulation of ceramide. The impact of myricetin on the binding of annexin-V was significantly reduced, but not completely eliminated, by the nominal removal of extracellular Ca2+. Myricetin triggers eryptosis, which is accompanied and, at least in part, caused by Ca2+ influx, oxidative stress and increase of ceramide abundance.

Blocking P2X7 by intracerebroventricular injection of P2X7-specific nanobodies reduces stroke lesions

BackgroundPrevious studies have demonstrated that purinergic receptors could be therapeutic targets to modulate the inflammatory response in multiple models of brain diseases. However, tools for the selective and efficient targeting of these receptors are lacking. The development of new P2X7-specific nanobodies (nbs) has enabled us to effectively block the P2X7 channel.MethodsTemporary middle cerebral artery occlusion (tMCAO) in wild-type (wt) and P2X7 transgenic (tg) mice was used to model ischemic stroke. Adenosine triphosphate (ATP) release was assessed in transgenic ATP sensor mice. Stroke size was measured after P2X7-specific nbs were injected intravenously (iv) and intracerebroventricularly (icv) directly before tMCAO surgery. In vitro cultured microglia were used to investigate calcium influx, pore formation via 4,6-diamidino-2-phenylindole (DAPI) uptake, caspase 1 activation and interleukin (IL)-1β release after incubation with the P2X7-specific nbs.ResultsTransgenic ATP sensor mice showed an increase in ATP release in the ischemic hemisphere compared to the contralateral hemisphere or the sham-treated mice up to 24 h after stroke. P2X7-overexpressing mice had a significantly greater stroke size 24 h after tMCAO surgery. In vitro experiments with primary microglial cells demonstrated that P2X7-specific nbs could inhibit ATP-triggered calcium influx and the formation of membrane pores, as measured by Fluo4 fluorescence or DAPI uptake. In microglia, we found lower caspase 1 activity and subsequently lower IL-1β release after P2X7-specific nb treatment. The intravenous injection of P2X7-specific nbs compared to isotype controls before tMCAO surgery did not result in a smaller stroke size. As demonstrated by fluorescence-activated cell sorting (FACS), after stroke, iv injected nbs bound to brain-infiltrated macrophages but not to brain resident microglia, indicating insufficient crossing of the blood–brain barrier of the nbs. Therefore, we directly icv injected the P2X7-specific nbs or the isotype nbs. After icv injection of 30 µg of P2X7 specific nbs, P2X7 specific nbs bound sufficiently to microglia and reduced stroke size.ConclusionMechanistically, we can show that there is a substantial increase of ATP locally after stroke and that blockage of the ATP receptor P2X7 by icv injected P2X7-specific nbs can reduce ischemic tissue damage.

"Calcium bombs" as harbingers of synaptic pathology and their mitigation by magnesium at murine neuromuscular junctions.

Excitotoxicity is thought to be an important factor in the onset and progression of amyotrophic lateral sclerosis (ALS). Evidence from human and animal studies also indicates that early signs of ALS include degeneration of motor nerve terminals at neuromuscular junctions (NMJs), before degeneration of motor neuron cell bodies. Here we used a model of excitotoxicity at NMJs in isolated mouse muscle, utilizing the organophosphorus (OP) compound omethoate, which inhibits acetylcholinesterase activity. Acute exposure to omethoate (100 μM) induced prolonged motor endplate contractures in response to brief tetanic nerve stimulation at 20–50 Hz. In some muscle fibers, Fluo-4 fluorescence showed association of these contractures with explosive increases in Ca2+ (“calcium bombs”) localized to motor endplates. Calcium bombs were strongly and selectively mitigated by increasing Mg2+ concentration in the bathing medium from 1 to 5 mM. Overnight culture of nerve-muscle preparations from WldS mice in omethoate or other OP insecticide components and their metabolites (dimethoate, cyclohexanone, and cyclohexanol) induced degeneration of NMJs. This degeneration was also strongly mitigated by increasing [Mg2+] from 1 to 5 mM. Thus, equivalent increases in extracellular [Mg2+] mitigated both post-synaptic calcium bombs and degeneration of NMJs. The data support a link between Ca2+ and excitotoxicity at NMJs and suggest that elevating extracellular [Mg2+] could be an effective intervention in treatment of synaptic pathology induced by excitotoxic triggers.

Effect of zinc and copper ions on cadmium-induced toxicity in rat cultured cortical neurons

BackgroundCadmium is a highly toxic heavy metal that is capable of accumulating in the body and causing neurodegeneration. However, the effect of other trace elements on Cd2+ toxicity is currently poorly understood. The aim of this work was to study the effect of Zn2+ and Cu2+ ions on cadmium-induced death of neurons in the cerebral cortex. MethodsThe work was performed on rat cortical primary cultures. The MTT test was used to determine the cytotoxicity effects. Analysis of intracellular Ca2+ concentration was assessed by the Fluo-4 AM calcium indicator that exhibit an increase in fluorescence upon binding Ca2+. MitoSOX Red (mitochondrial superoxide indicator) was used to measuring mitochondrial ROS content in live cells. ResultsIn this article, we show that the administration of CdCl2 (0.005–0.02 mM) for 48 h induced an increase in dose-dependent death rate of cultured cortical neurons. Mature neurons were more sensitive to the damaging effects of Cd2+ than immature ones. ZnCl2 (0.01–0.03 mM) significantly protected neurons from this toxic effect. In contrast to ZnCl2, CuCl2 (0.01 mM) increased cadmium neurotoxicity. Using Fluo-4 AM, measurements of intracellular calcium ions demonstrated that 24 h-exposure to Cd2+ induced intensive increase in Fluo-4 fluorescence in neurons, which was significantly reduced by zinc ions. CuCl2 increased the cadmium-induced Fluo-4 and MitoSOX Red fluorescence in neurons. The chelator of intracellular Ca2+ BAPTA significantly decreased Cd2+-induced intensive increase in Fluo-4 fluorescence in cells. ConclusionThe data obtained by us indicate that Zn2+ and Cu2+ can affect the neurotoxicity of cadmium in different directions: Zn2+ weaken the violation of intracellular calcium homeostasis caused by cadmium, preventing cell death, while Cu2+ potentiate the increase in the level of free intracellular calcium induced by cadmium and the development of mitochondrial dysfunction with an increase in the production of free radicals in differentiated cultured neurons of the cerebral cortex, which ultimately stimulates cytotoxicity.

Semi-refined carrageenan induces eryptosis in a Ca<sup>2+</sup>-dependent manner

Background: Semi-refined carrageenan (food additive E407a) is a widely used thickener, which has been reported to exert toxic and pro-inflammatory effects. In particular, there is accumulating evidence that it induces eryptosis, i.e. a programmed cell death of eryptocytes, via ROS-mediated pathways. However, the role of Ca2+-dependent mechanisms in E407a-induced eryptosis is not elucidated. Material and methods: Semi-refined carrageenan at concentrations of 0 mg/ml, 1 mg/ml, 5 mg/ml and 10 mg/ml was incubated with blood of intact female WAG rats (n=9) for 24 h in RPMI and fetal bovine serum. After 24 h, the samples were used to obtain erythrocyte suspensions. The obtained suspensions were stained with a Ca2+-sensitive FLUO4 AM probe (30 min, 2.5 µM). The fluorescence of FLUO4 in erythrocytes was detected by a BD FACSCanto II flow cytometer. Results: The intracellular Ca2+ levels are proportional to the fluorescence of FLUO4. The mean fluorescence intensities (MFI) were compared. Low levels (1 mg/ml) of E407a had no impact on Ca2+ concentrations in erythrocytes (p>0.05). On the contrary, high concentrations (5 mg/ml and 10 mg/ml) of this food additive promoted an increase in the intracellular Ca2+ levels. The MFI values were 2.3- and 2.5-fold higher, respectively (p<0.0001). In addition, the exposure to E407a at concentrations of 5 mg/ml and 10 mg/ml (p<0.0001) increased the percentage of cells with high FLUO4 fluorescence. Conclusion: Food additive E407a induces eryptosis in a Ca2+-dependent manner.

Mitochondrial Superoxide is the Key for Promoting Cell Migration in Wound Healing

Introduction: The focus of current study was to investigate the role of mitochondrial superoxide for promoting cell migration in healing responses. Methods: To simulate the skin wound healing process, scratch wound assay in A549 cells was utilized. Subsequently, mitochondrial superoxide and intracellular calcium flux (Ca2+) were measured by MitoSox red reagent and Fluo-4 staining. Paraquat (PQ), N-acetyl cysteine (NAC), superoxide dismutase (SOD) mimics (EUK-134), free radical scavenge (MCI-186), and diphenyliodonium (DPI) were added into medium to evaluate the influences of reactive oxygen species (ROS) and superoxide on cell migration. Results: Compared with before wound (BW), mitochondrial superoxide increased time-dependent manner. Correspondingly, Ca2+ transients was rapidly elevated after scratch wound and gradually declined toward an steady level, as evidenced by Fluo-4 fluorescence intensity. Scratch wound assay displayed that cell migration in PQ 0.1 mM group was stronger than that of Control group, whilst it was restrained after administration of 10 mM NAC. Additionally, cell migration in EUK-134 and MCI-186 group was conspicuously lower than that of Control group and similar with the degree of inhibiting role of DPI, indicating that mitochondrial superoxide served the crux influence on promoting cell migration after scratch. Conclusion: ROS and superoxide production during scratch wound facilitated cell migration. Importantly, mitochondrial superoxide played the positive effects on healing response.

TRPC5 is essential in endothelium-dependent contraction of aorta from diet-induced obese mice

The role of the Ca2+-permeable ion channel TRPC5 in regulating vasocontraction in obesity is poorly understood. Here, we investigated whether TRPC5 contributes to vascular dysfunction in obesity by promoting endothelium-dependent contraction via activation of cytosolic phospholipase A2 (cPLA2) in the aortic endothelial cells of obese mice. Acetylcholine-induced endothelium-dependent relaxation and contraction in the aorta were measured using wire myography. PLA2 activity was measured by the fluorogenic PLA2 substrate Bis-BODIPY™ FL C11-PC. The intracellular Ca2+ level in response to acetylcholine was measured by Fluo-4 fluorescence. Endothelium-derived contracting factors were assessed by enzyme immunoassay. Diet-induced obesity (DIO) attenuated endothelium-dependent vasodilation, enhanced endothelium-dependent contraction (EDC), and increased the expression of TRPC5 in the mouse aorta. Activation of TRPC5 promoted EDC in the wild-type mouse aorta, whereas pharmacological inhibition and genetic knockout of TRPC5 decreased EDC in the DIO mouse aorta. Moreover, cPLA2 phosphorylation and activity were higher in aortic endothelial cells from DIO mice, and this was attenuated by inhibition and knockout of TRPC5. Cyclooxygenase 2 (COX-2) expression was increased in DIO mouse endothelium and was decreased by a TRPC5 inhibitor and knockout of TRPC5. Release of prostaglandins F2α (PGF2α) and E2 (PGE2) was involved in TRPC5-regulated EDC in DIO mice. This study demonstrated that TRPC5 contributes to endothelial and vascular dysfunction and is involved in EDC through activation of cPLA2 and enhanced COX-2-PGF2α/PGE2 levels in DIO mice.

Electrically Controlled Neurochemical Delivery from Microelectrodes for Focal and Transient Modulation of Cellular Behavior.

Electrically controlled drug delivery of neurochemicals and biomolecules from conducting polymer microelectrode coatings hold great potentials in dissecting neural circuit or treating neurological disorders with high spatial and temporal resolution. The direct doping of a drug into a conducting polymer often results in low loading capacity, and the type of molecule that can be released is limited. Poly(3,4-ethylenedioxythiophene) (PEDOT) doped with sulfonated silica nanoparticles (SNP) has been developed as a more versatile platform for drug delivery. In this work, we demonstrate that neurochemicals with different surface charge, e.g., glutamate (GLU), gamma-Aminobutyric acid (GABA), dopamine (DA), 6,7-Dinitroquinoxaline- 2,3-dione (DNQX) and bicuculline, can be, respectively, incorporated into the SNP and electrically triggered to release repeatedly. The drug loaded SNPs were incorporated in PEDOT via electrochemical deposition on platinum microelectrodes. After PEDOT/SNP(drug) coating, the charge storage capacity (CSC) increased 10-fold to 55 ± 3 mC/cm2, and the impedance at 1 kHz was also reduced approximately 6-fold. With the aid of a porous SNP, the loading capacity and number of releases of GLU was increased >4-fold and 66-fold, respectively, in comparison to the direct doping of PEDOT with GLU (PEDOT/GLU). The focal release of GLU and GABA from a PEDOT/SNP (drug) coated microelectrode were tested in cultured neurons using Ca imaging. The change in fluo-4 fluorescence intensity after electrically triggered GLU (+6.7 ± 2.9%) or GABA (−6.8 ± 1.6%) release indicated the successful modulation of neural activities by neurotransmitter release. In addition to activating neural activities, glutamate can also act on endothelial cells to stimulate nitric oxide (NO) release. A dual functional device with two adjacent sensing and releasing electrodes was constructed and we tested this mechanism in endothelial cell cultures. In endothelial cells, approximately 7.6 ± 0.6 nM NO was detected in the vicinity of the NO sensor within 6.2 ± 0.5 s of GLU release. The rise time of NO signal, T0–100, was 14.5 ± 2.2 s. In summary, our work has demonstrated (1) a platform that is capable of loading and releasing drugs with different charges; (2) proof of concept demonstrations of how focal release of drugs can be used as a pharmacological manipulation to study neural circuitry or NO’s effect on endothelial cells.

Epidemic dropsy toxin, sanguinarine chloride, stimulates sucrose-sensitive hemolysis and breakdown of membrane phospholipid asymmetry in human erythrocytes

Sanguinarine (SGN) is a benzophenathridine alkaloid extracted from Sanguinaria canadensis plant. SGN is incriminated in epidemic dropsy (ED) characterized by multiple-organ failure and anemia. Nevertheless, how SGN leads to anemia of ED remains poorly understood. This study was thus initiated to investigate the interaction of SGN with human red blood cells (RBCs) and to delineate associated molecular mechanisms. Heparin- and EDTA-anticoagulated blood was collected from healthy participants and whole blood was analyzed for a complete blood count, while isolated RBCs were examined for hemolytic and eryptotic markers following exposure to 1–100 μM SGN for 24 h at 37 °C. Calcium was measured by Fluo4/AM, hemolysis by hemoglobin leakage, membrane scrambling by Annexin V-FITC, cell size by forward scatter (FSC), cell granularity by side scatter (SSC), and oxidative stress by H2DCFDA. SGN led to increased Fluo4 fluorescence and dose-dependent hemolysis which was not ameliorated by exclusion of extracellular Ca2+ but was nevertheless sensitive to hyperosmotic conditions and to the presence of aspirin. SGN also caused significant increase in Annexin V-positive cells, decreased FSC and SSC values, and elevated DCF fluorescence. Moreover, significantly reduced lymphocyte and basophil percentages along with selective toxicity to platelets was noted. Collectively, SGN possesses sucrose- and cyclooxygenase-sensitive hemolytic potential and elicits eryptosis characterized by Ca2+ accumulation, phosphatidylserine externalization, morphological alterations including cell shrinkage and loss of granularity, and oxidative stress. In conclusion, this report reveals a novel activity of SGN against human RBCs and informs prospective policies in ED prevention and management.

Can a chloride channel blocker mitigate muscle fatigue?

Can a chloride channel blocker mitigate muscle fatigue?

Physcion Induces Hemolysis and Premature Phosphatidylserine Externalization in Human Erythrocytes

The prevalence of cancer-associated anemia (CIA) is high, and the mechanisms governing its development remain poorly understood. Eryptosis, the suicidal cell death of red blood cells (RBCs), may account for CIA as it is triggered by clinically approved chemotherapeutics including cisplatin and paclitaxel. Physcion (PSN), an anthraquinone extracted from rhubarb and other plants, has shown great promise as an anticancer agent. However, the potential toxicity of PSN to RBCs remains elusive. RBCs were isolated from heparinized blood, and incubated with 10-100 µM of PSN for 24 h at 37 °C. Hemolysis was photometrically calculated from hemoglobin concentration in the medium at 405 nm, while flow cytometry was employed to investigate cardinal markers of eryptosis. Phosphatidylserine (PS) exposure was detected by Annexin-V-fluorescein isothiocyanate (FITC), intracellular calcium by Fluo4/AM, cellular volume from forward scatter (FSC), and oxidative stress by 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA). PSN induced overt hemolysis at 50 and 100 µM which was not mediated through calcium influx, protein kinase C, casein kinase 1α, or receptor-interacting protein 1. Moreover, PSN caused significant increase in Annexin-V-FITC and Fluo4 fluorescence with no appreciable influence on FSC or DCF values. Accordingly, PSN stimulates premature eryptosis characterized by PS externalization and intracellular calcium overload without cell shrinkage or oxidative damage. In conclusion, this report shows, for the first time, that PSN is cytotoxic to RBCs by inducing hemolysis and programmed cell death which may limit its success as a chemotherapeutic agent.

In Esophageal Squamous Cells From Eosinophilic Esophagitis Patients, Th2 Cytokines Increase Eotaxin-3 Secretion Through Effects on Intracellular Calcium and a Non-Gastric Proton Pump

In upper airway cells, T helper 2 cytokines that signal through interleukin-4 (IL-4) receptor-α have been shown to stimulate eotaxin-3 secretion via a nongastric proton pump (ngH+,K+ATPase). To seek novel targets for eosinophilic esophagitis (EoE) treatments, we evaluated ngH+,K+ATPase expression in EoE squamous cells, and explored molecular pathways involved in eotaxin-3 secretion by IL-4 receptor-α signaling. ngH+,K+ATPase expression in EoE cells was evaluated by quantitative real-time polymerase chain reaction and Western blotting. IL-4-stimulated eotaxin-3 secretion was measured by enzyme-linked immunosorbent assay after treatment with omeprazole, SCH 28080 (potassium-competitive acid blocker), ethylene glycol-bis(β-aminoethyl)-N,N,N',N'-tetraacetoxymethyl ester (calcium chelator), 2-aminoethoxydiphenyl borate (inhibitor of endoplasmic reticulum calcium release), verapamil, and diltiazem (L-type calcium channel inhibitors). Intracellular calcium transients were measured by Fluo-4 fluorescence. Key experiments were confirmed in EoE primary cells and in RNA sequencing datasets from mucosal biopsies of patients with EoE and controls. EoE cells expressed ngH+,K+ATPase messenger RNA and protein. Omeprazole and SCH 28080 decreased IL-4-stimulated eotaxin-3 secretion. IL-4 increased intracellular calcium transients, and IL-4-stimulated eotaxin-3 secretion was blocked by ethylene glycol-bis(β-aminoethyl)-N,N,N',N'-tetraacetoxymethyl ester, 2-aminoethoxydiphenyl borate, verapamil, and diltiazem. The combination of omeprazole and verapamil suppressed IL-4-stimulated eotaxin-3 secretion more than either agent alone. EoE biopsies expressed higher ngH+,K+ATPase and exhibited more calcium signaling than controls. EoE cells express a nongastric proton pump that mediates T helper 2 cytokine-stimulated eotaxin-3 secretion. IL-4 induces calcium release from the endoplasmic reticulum and calcium entry via L-type calcium channels, increasing intracellular calcium that contributes to eotaxin-3 secretion by EoE cells. L-type calcium channel inhibitors block T helper 2 cytokine-stimulated eotaxin-3 secretion, suggesting a potential role for these agents in EoE treatment.