Artificial oocyte activation with ionomycin compared with A23187 among patients at risk of failed or impaired fertilization.

RESEARCH QUESTION: Do fertilization rates differ between intracytoplasmic sperm injection (ICSI) cycles treated with artificial oocyte activation (AOA) using 10 µmol/l ionomycin or commercial A23187 in women at risk of failed or impaired fertilization? DESIGN: This single-centre, 7-year retrospective cohort study included 157 couples with a history of total fertilization failure (TFF, 0%) or low fertilization (<30%) after ICSI, or with severe oligo-astheno-teratozoospermia (OAT) in the male partner. Couples and underwent 171 ICSI-AOA cycles using either 10 µmol/l ionomycin or commercial A23187. The embryological and clinical outcomes were compared. RESULTS: Fertilization rates in the ionomycin group were significantly higher than those in the A23187 group for all three subgroups (TFF, 46.9% versus 28.4%, P = 0.002; low fertilization, 67.7% versus 49.2%, P < 0.001; severe OAT, 66.4% versus 31.6%, P < 0.001). AOA with ionomycin significantly increased the day 3 cleavage rate (P = 0.009) when compared with A23187 in the low fertilization group, but not in the TFF or severe OAT group (both P > 0.05). The rates of day 3 good-quality embryos, clinical pregnancy, implantation and live birth, and the cumulative live birth, did not differ between the two groups (all P > 0.05). A total of 64 live births resulted in 72 healthy babies born. CONCLUSIONS: AOA with 10 µmol/l ionomycin may be more effective than commercial A23187 in improving oocyte activation in patients at risk of failed or impaired fertilization, especially in cases of sperm-related defects.

Significant differences in efficiency between two commonly used ionophore solutions for assisted oocyte activation (AOA): a prospective comparison of ionomycin and A23187.

PURPOSE: Despite the success of ICSI in treating severe male factor infertile patients, total fertilization failure (FF) still occurs in around 1-3% of ICSI cycles. To overcome FF, the use of calcium ionophores has been proposed to induce oocyte activation and restore fertilization rates. However, assisted oocyte activation (AOA) protocols and ionophores vary between laboratories, and the morphokinetic development underlying AOA remains understudied. METHODS: A prospective single-center cohort study involving 81 in vitro matured metaphase-II oocytes from 66 oocyte donation cycles artificially activated by A23187 (GM508 CultActive, Gynemed) (n=42) or ionomycin (n=39). Parthenogenesis was induced, and morphokinetic parameters (tPNa, tPNf, t2-t8, tSB, and tB) were compared between the 2 study groups and a control group comprising 39 2PN-zygotes from standard ICSI cycles. RESULTS: Ionomycin treatment resulted in higher activation rates compared to A23187 (38.5% vs 23.8%, p=0.15). Importantly, none of the A23187-activated parthenotes formed blastocysts. When evaluating the morphokinetic dynamics between the two ionophores, we found that tPNa and tPNf were significantly delayed in the group treated by A23187 (11.84 vs 5.31, p=0.002 and 50.15 vs 29.69, p=0.005, respectively). t2 was significantly delayed in A23187-activated parthenotes when compared to the double heterologous control embryo group. In contrast, the morphokinetic development of ionomycin-activated parthenotes was comparable to control embryos (p>0.05). CONCLUSION: Our results suggest that A23187 leads to lower oocyte activation rates and profoundly affects morphokinetic timings and preimplantation development in parthenotes. Despite our limited sample size and low parthenote competence, standardization and further optimization of AOA protocols may allow wider use and improved outcomes for FF cycles.

Effect of cholesterol-loaded cyclodextrin treatment of bovine sperm on capacitation timing.

Pre-loading bovine sperm with cholesterol prior to freezing is known to increase cryosurvival, though the timing of capacitation in these sperm has not been evaluated. The objective of this study was to determine if there is a potential delay in capacitation timing in these sperm due to the increased cholesterol content. Flow cytometric evaluation was utilized to assess viability, and stain technology to assess acrosome intactness (Propidium Iodide/FITC-PNA), intracellular calcium levels (Propidium Iodide/FLUO 3-AM) and membrane fluidity (Merocyanine 540/YO-PRO-1). Cholesterol-loaded cyclodextrin (CLC) (2 mg/mL) improved post-thaw viability to 61% from 45% in control sperm (p < .05). The addition of ionomycin (0.05 mM) induced capacitation in sperm by 1 h, resulting in increased intracellular calcium and increased acrosome reaction, and consequently viability loss by 3 h. Treatment with CLC significantly decreased membrane fluidity in sperm (p < .05). In conclusion, CLC-treated sperm required 1 h more to capacitate when compared with non-treated sperm based on percentage of live cells with high membrane disorder (p < .05). Increased cryosurvival and viability over time was observed, but longer time to capacitate may hinder fertilization capacity and/or require adjustments to timing of in vitro fertilization.

Efficacy of artificial oocyte activation in patients with embryo developmental problems: a sibling oocyte control study.

PURPOSE: To explore whether artificial oocyte activation (AOA) can improve embryo developmental potentiality and pregnancy outcomes for patients with a history of embryo developmental problem. METHODS: This was a retrospective study and candidate patients with embryo development problems were collected. A total of 1422 MII eggs from the enrolled 140 patients were randomized divided equally into 2 groups, half for the AOA group (AOA), and the rest of sibling mature eggs for the control group (non-AOA). The patients were further divided into two subgroups: (1) the rate of good-quality day 3 embryos was 0% (group 1, n = 66); (2) the rate of good-quality day 3 embryos ranged from 1 to 30% (group 2, n = 74). RESULTS: In the early embryonic growth, there were no significant differences in the outcomes of AOA and non-AOA groups in terms of normal fertilization rates, cleavage rates, day 3 good-quality embryo rates and available blastocyst rates (72.7% vs. 79.3%, 97.4% vs. 98.0%, 20.1% vs. 19.7%, 6.6% vs. 8.4% in group 1, respectively; 77.7% vs. 81.9%, 98.1% vs. 97.0%, 25.8% vs. 22.1%, 9.6% vs. 9.3% in group 2, respectively). In the late embryonic growth, no significant differences were found in biochemical and clinical pregnancy rates, implantation rates, miscarriage rates, and live-birth rates (50.0% vs. 45.2%, 45.2% vs. 40.5%, 37.3% vs. 31.3%, 10.5% vs. 11.8%, 40.5% vs. 35.7%, respectively) between two groups. In addition, neonatal outcomes were similar in both the groups as well. CONCLUSION: Our study demonstrated that the AOA using ionomycin 1 h after ICSI did not bring benefits to the early or late development of embryos derived from patients with a history of embryo developmental problems.

Characterization of Citrullination Sites in Neutrophils and Mast Cells Activated by Ionomycin via Integration of Mass Spectrometry and Machine Learning.

Citrullination is an important post-translational modification implicated in many diseases including rheumatoid arthritis (RA), Alzheimer's disease, and cancer. Neutrophil and mast cells have different expression profiles for protein-arginine deiminases (PADs), and ionomycin-induced activation makes them an ideal cellular model to study proteins susceptible to citrullination. We performed high-resolution mass spectrometry and stringent data filtration to identify citrullination sites in neutrophil and mast cells treated with and without ionomycin. We identified a total of 833 validated citrullination sites on 395 proteins. Several of these citrullinated proteins are important components of pathways involved in innate immune responses. Using this benchmark primary sequence data set, we developed machine learning models to predict citrullination in neutrophil and mast cell proteins. We show that our models predict citrullination likelihood with 0.735 and 0.766 AUCs (area under the receiver operating characteristic curves), respectively, on independent validation sets. In summary, this study provides the largest number of validated citrullination sites in neutrophil and mast cell proteins. The use of our novel motif analysis approach to predict citrullination sites will facilitate the discovery of novel protein substrates of protein-arginine deiminases (PADs), which may be key to understanding immunopathologies of various diseases.

Identification of a selective manganese ionophore that enables nonlethal quantification of cellular manganese.

Available assays for measuring cellular manganese (Mn) levels require cell lysis, restricting longitudinal experiments and multiplexed outcome measures. Conducting a screen of small molecules known to alter cellular Mn levels, we report here that one of these chemicals induces rapid Mn efflux. We describe this activity and the development and implementation of an assay centered on this small molecule, named manganese-extracting small molecule (MESM). Using inductively-coupled plasma-MS, we validated that this assay, termed here "manganese-extracting small molecule estimation route" (MESMER), can accurately assess Mn in mammalian cells. Furthermore, we found evidence that MESM acts as a Mn-selective ionophore, and we observed that it has increased rates of Mn membrane transport, reduced cytotoxicity, and increased selectivity for Mn over calcium compared with two established Mn ionophores, calcimycin (A23187) and ionomycin. Finally, we applied MESMER to test whether prior Mn exposures subsequently affect cellular Mn levels. We found that cells receiving continuous, elevated extracellular Mn accumulate less Mn than cells receiving equally-elevated Mn for the first time for 24 h, indicating a compensatory cellular homeostatic response. Use of the MESMER assay versus a comparable detergent lysis-based assay, cellular Fura-2 Mn extraction assay, reduced the number of cells and materials required for performing a similar but cell lethality-based experiment to 25% of the normally required sample size. We conclude that MESMER can accurately quantify cellular Mn levels in two independent cells lines through an ionophore-based mechanism, maintaining cell viability and enabling longitudinal assessment within the same cultures.

Assisted oocyte activation effects on the morphokinetic pattern of derived embryos.

OBJECTIVE: Assisted oocyte activation (AOA) can restore fertilization rates after IVF/ICSI cycles with fertilization failure. AOA is an experimental technique, and its downstream effects remain poorly characterized. Clarifying the relationship between AOA and embryo, morphokinetics could offer complementary insights into the quality and viability of the embryos obtained with this technique. The aim of this study is to compare the preimplantation morphokinetic development of embryos derived from ICSI-AOA (experimental group) vs. ICSI cycles (control group). METHODS: A retrospective cohort study was carried out with 141 embryos from fresh oocyte donation cycles performed between 2013 and 2017; 41 embryos were derived from 7 ICSI-AOA cycles and 100 embryos from 18 ICSI cycles. Morphokinetic development of all embryos was followed using a time-lapse system. RESULTS: We show that embryos from both groups develop similarly for most milestones, with the exception of the time of second polar body extrusion (tPB2) and the time to second cell division (t3). CONCLUSIONS: We conclude that ionomycin mediated AOA does not seem to affect the morphokinetic pattern of preimplantation embryo development, despite the alterations found in tPB2 and t3, which could directly reflect the use of a Ca2+ ionophore as a transient and quick non-physiologic increase of free intracytoplasmic Ca2+.

CD9 Upregulation-Decreased CCL21 Secretion in Mesenchymal Stem Cells Reduces Cancer Cell Migration.

Tetraspanin CD9 is widely expressed on various cell types, such as cancer cells and mesenchymal stem cells (MSCs), and/or cell-released exosomes. It has been reported that exosomal CD9 plays an important role in intercellular communications involved in cancer cell migration and metastasis. However, reports on the effect of the CD9 of MSCs or MSC-derived exosomes on cancer cell migration are still lacking. In this study, using a transwell migration assay, we found that both dextran-coated iron oxide nanoparticles (dex-IO NPs) and ionomycin stimulated exosomal CD9 expression in human MSCs (hMSCs); however, hMSCs could not deliver them to melanoma cells to affect cell migration. Interestingly, a reduced migration of melanoma cell line was observed when the ionomycin-incubated hMSC-conditioned media but not dex-IO NP-labeled hMSC-conditioned media were in the bottom chamber. In addition, we found that dex-IO NPs decreased cellular CD9 expression in hMSCs but ionomycin increased this. Simultaneously, we found that ionomycin suppressed the expression and secretion of the chemokine CCL21 in hMSCs. The silencing of CD9 demonstrated an inhibitory role of cellular CD9 in CCL21 expression in hMSCs, suggesting that ionomycin could upregulate cellular CD9 to decrease CCL21 expression and secretion of hMSCs, which would reduce the migration of B16F10, A549 and U87MG cancer cell lines due to chemoattraction reduction of CCL21. The present study not only highlights the important role of bone marrow-derived hMSCs' CD9-mediated CCL21 regulation in cancer bone metastasis but also suggests a new distinct pharmaceutical strategy for prevention or/and therapy of cancer metastasis.

Beneficial effects of naringenin and morin on interleukin-5 and reactive oxygen species production in BALB/c mice with ovalbumin-induced asthma.

We investigated the effects of naringenin and morin on IL-5 and ROS production in PMA+ionomycin-treated EL-4 cells with the corroboration of their antioxidant and anti-inflammatory properties using an asthma-induced mouse model. The EL-4 cell line was used to study the outcomes of naringenin or morin, followed by cell viability studies. Western blot analysis and ELISA test were used to determine Th2 mediated cytokines. In vivo studies were carried out on BALB/c mice to induce allergic asthma using ovalbumin administered intraperitoneally. Intracellular ROS was determined using 2',7'-dichlorodihydrofluorescein diacetate, followed by serum enzymatic (AST and ALT) estimations and inflammatory cell count in the bronchoalveolar lavage fluid (BALF) and lung tissues. Histopathological studies were conducted to examine lung tissue-stained architecture. Our findings suggested that naringenin and morin significantly suppressed IL-5 and ROS production via various pathways. Interestingly, by reducing NFAT activity, naringenin and morin stimulated HO-1 expression, thereby suppressing IL-5 secretion due to regulating the transcription factor Nrf2 via P13/Akt or ERK/JNK signalling pathways in EL-4 cells, demonstrating the involvement of HO-1 expression in inhibiting asthmatic inflammation. The increased inflammatory cells in the BALF were substantially decreased by both naringenin and morin, followed by inhibition in the elevated Th-2 cytokines levels. The TNF-α protein levels in an allergic asthma mouse model were significantly reduced by suppressing Akt phosphorylation and eosinophil formation. Recent findings confirmed that naringenin and morin possess the potential to control asthma-related immune responses through antioxidant and anti-inflammatory properties, indicating potential therapeutic agents or functional foods.

Ionomycin-induced mouse oocyte activation can disrupt preimplantation embryo development through increased reactive oxygen species reaction and DNA damage.

Oocyte activation induced by calcium oscillations is an important process in normal fertilization and subsequent embryogenesis. In the clinical-assisted reproduction, artificial oocyte activation (AOA) is an effective method to improve the clinical outcome of patients with null or low fertilization rate after ICSI. However, little is known about the effect of AOA on preimplantation embryo development in cases with normal fertilization by ICSI. Here, we used ionomycin at different concentrations to activate oocytes after ICSI with normal sperm and evaluated energy metabolism and preimplantation embryo development. We found that a high concentration of ionomycin increased the frequency and amplitude of calcium oscillation patterns, affecting the balance of mitochondrial energy metabolism, leading to increased reactive oxygen species (ROS) and decreased ATP. Eventually, it increases DNA damage and decreases blastocyst formation. In addition, the addition of vitamin C to the culture medium ameliorated the increase in ROS and DNA damage and rescued the abnormal embryo development caused by excessive ionomycin activation. This study provides a perspective that the improper application of AOA may have adverse effects on preimplantation embryo development. Thus, clinical AOA treatment should be cautiously administered.

IL-10-producing regulatory B cells exhibit functional defects and play a protective role in severe endotoxic shock.

Dysregulated host immune homeostasis in sepsis is life-threatening even after a successfully treated bacterial infection. Lipopolysaccharide (LPS) is an endotoxin that is a major contributor to the aberrant immune responses and endotoxic shock in gram-negative bacterial sepsis. However, the current knowledge of the role of B cells in endotoxic shock is limited. Here, we report that CD1d expression in B cells and the percentage of CD5+CD1dhi regulatory B (Breg) cells decreased in a mouse model of endotoxic shock. Interestingly, IL-10 but not FasL expression in CD5+CD1dhi Breg cells in response to endotoxin was dramatically reduced in severe septic shock mice, and the regulatory function of CD5+CD1dhi Breg cells in vitro to control the Th1 response was also diminished. Adoptive transfer of CD5+CD1dhi Breg cells from healthy WT mice but not IL-10 deficient mice downregulated the IFN-γ secretion in CD4+ T cells and conferred protection against severe endotoxic shock in vivo. Our findings demonstrate the change and notable therapeutic potential of IL-10-producing Breg cells in endotoxic shock.

Combining Adhesive Nanostructured Surfaces and Costimulatory Signals to Increase T Cell Activation.

Adoptive cell therapies are showing very promising results in the fight against cancer. However, these therapies are expensive and technically challenging in part due to the need of a large number of specific T cells, which must be activated and expanded in vitro. Here we describe a method to activate primary human T cells using a combination of nanostructured surfaces functionalized with the stimulating anti-CD3 antibody and the peptidic sequence arginine-glycine-aspartic acid, as well as costimulatory agents (anti-CD28 antibody and a cocktail of phorbol 12-myristate 13-acetate, ionomycin, and protein transport inhibitors). Thus, we propose a method that combines nanotechnology with cell biology procedures to efficiently produce T cells in the laboratory, challenging the current state-of-the-art expansion methodologies.

Ca2+ -dependent down-regulation of human histamine H1 receptors in Chinese hamster ovary cells.

Gq/11 protein-coupled human histamine H1 receptors in Chinese hamster ovary cells stimulated with histamine undergo clathrin-dependent endocytosis followed by proteasome/lysosome-mediated down-regulation. In this study, we evaluated the effects of a sustained increase in intracellular Ca2+ concentrations induced by a receptor-bypassed stimulation with ionomycin, a Ca2+ ionophore, on the endocytosis and down-regulation of H1 receptors in Chinese hamster ovary cells. All cellular and cell-surface H1 receptors were detected by the binding of [3 H]mepyramine to intact cells sensitive to the hydrophobic and hydrophilic H1 receptor ligands, mepyramine and pirdonium, respectively. The pretreatment of cells with ionomycin markedly reduced the mepyramine- and pirdonium-sensitive binding sites of [3 H]mepyramine, which were completely abrogated by the deprivation of extracellular Ca2+ and partially by a ubiquitin-activating enzyme inhibitor (UBEI-41), but were not affected by inhibitors of calmodulin (W-7 or calmidazolium) and protein kinase C (chelerythrine or GF109203X). These ionomycin-induced changes were also not affected by inhibitors of receptor endocytosis via clathrin (hypertonic sucrose) and caveolae/lipid rafts (filipin or nystatin) or by inhibitors of lysosomes (E-64, leupeptin, chloroquine, or NH4 Cl), proteasomes (lactacystin or MG-132), and a Ca2+ -dependent non-lysosomal cysteine protease (calpain) (MDL28170). Since H1 receptors were normally detected by confocal immunofluorescence microscopy with an antibody against H1 receptors, even after the ionomycin treatment, H1 receptors appeared to exist in a form to which [3 H]mepyramine was unable to bind. These results suggest that H1 receptors are apparently down-regulated by a sustained increase in intracellular Ca2+ concentrations with no process of endocytosis and lysosomal/proteasomal degradation of receptors.

Sonidegib, a Novel Inhibitor of Suicidal Erythrocyte Death.

BACKGROUND/AIMS: The Hedgehog pathway disrupting drug sonidegib is used in the treatment of basal cell carcinoma. Side effects of sonidegib include anemia, which could result either from impaired erythropoiesis or from loss of erythrocytes e.g. due to suicidal erythrocyte death or eryptosis, which is characterized by cell membrane scrambling with phosphatidylserine translocation to the cell surface and by cell shrinkage. Eryptosis is stimulated by cell stress, including energy depletion, hyperosmotic shock, oxidative stress and excessive increase of cytosolic Ca2+ activity ([Ca2+]i). The present study explored, whether sonidegib exerts an effect on eryptosis. METHODS: Human erythrocytes have been treated with energy depletion (glucose withdrawal for 48 hours), hyperosmotic shock (addition of 550 mM sucrose for 6 hours), oxidative stress (addition of 0.3 mM tert-butylhydroperoxide [tBOOH] for 50 min) or Ca2+ ionophore ionomycin (1 µM for 60 min) in absence and presence of sonidegib (2-6 µg/ ml). After treatment flow cytometry was employed to quantify phosphatidylserine exposure at the cell surface from annexin-V-binding, and cell volume from forward scatter. Hemolysis was estimated from the hemoglobin concentration in the supernatant. RESULTS: In the absence of cell stress exposure to sonidegib did not significantly modify annexin-V-binding or forward scatter, but triggered hemolysis. Energy depletion, hyperosmotic shock, oxidative stress and ionomycin, all markedly and significantly increased the percentage of annexin-V-binding erythrocytes, and decreased the forward scatter. Sonidegib significantly blunted the effect of energy depletion, hyperosmotic shock, and oxidative stress, but not of ionomycin on annexin-V-binding. Sonidegib further significantly blunted the effect of energy depletion, but not of hyperosmotic shock, oxidative stress, and ionomycin on forward scatter. CONCLUSIONS: Sonidegib is a novel inhibitor of erythrocyte cell membrane scrambling following energy depletion, hyperosmotic shock and oxidative stress.

Inhibition of Erythrocyte Cell Membrane Scrambling Following Energy Depletion and Hyperosmotic Shock by Alectinib.

BACKGROUND/AIMS: The anaplastic lymphoma kinase (ALK) inhibitor alectinib is clinically used for the treatment of ALK positive non-small-cell lung cancer. At least in part the substance is effective by triggering suicidal death or apoptosis of tumor cells. Erythrocytes are lacking mitochondria and nuclei, key organelles of apoptosis but are, similar to apoptosis of nucleated cells, able to enter suicidal erythrocyte death or eryptosis. Stimulators of eryptosis include energy depletion, hyperosmotic shock, oxidative stress, and increase of cytosolic Ca2+ activity ([Ca2+]i). The present study explored, whether alectinib influences eryptosis. METHODS: Flow cytometry was employed to quantify phosphatidylserine exposure at the cell surface from annexin-V-binding and cell volume from forward scatter. Measurements were made without or with energy depletion (glucose deprivation for 48 hours), hyperosmotic shock (+550mM sucrose for 6 hours), oxidative stress (50 min exposure to 0.3 mM tert-butylhydroperoxide), and Ca2+ loading (60 minutes treatment with 1 µM Ca2+ ionophore ionomycin). RESULTS: A 48 hours exposure of human erythrocytes to alectinib (150-600 ng/ml) did not significantly modify the percentage of annexin-V-binding cells and forward scatter. Energy depletion, hyperosmotic shock, oxidative stress and Ca2+ loading were each followed by profound and significant increase of the percentage annexin-V-binding erythrocytes and a significant decrease of forward scatter. The effects of energy depletion and hyperosmotic shock, but not of oxidative stress or Ca2+ loading on annexin-V-binding were significantly blunted in the presence of alectinib (150-600 ng/ml). In none of the conditions was forward scatter significantly modified by alectinib. CONCLUSION: Alectinib inhibits cell membrane scrambling following energy depletion and hyperosmotic shock.

Resveratrol dimer trans-ε-viniferin prevents rotaviral diarrhea in mice by inhibition of the intestinal calcium-activated chloride channel.

We previously identified, by a natural-product screen, resveratrol oligomers as inhibitors of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel. Here, we report the resveratrol dimer trans-ε-viniferin (TV) and tetramer r-2-viniferin (RV) as inhibitors of the intestinal calcium-activated chloride channel (CaCC) and demonstrate their antisecretory efficacy in a neonatal mouse model of rotaviral diarrhea. Short-circuit measurements show inhibition of CaCC current in the human colonic cell line HT-29 by TV and RV with IC50∼1 and 20µM, respectively. TV primarily inhibited the physiologically relevant, long-term CaCC current following agonist stimulation, without effect on cytoplasmic Ca2+ signaling. TV and RV inhibited short-circuit current in mouse colon as well. In a neonatal mouse model of rotaviral secretory diarrhea produced by oral inoculation with rotavirus, 2µg TV or 11µg RV inhibited secretory diarrhea by >50%, without effect on the rotaviral infection. Our results support the antisecretory efficacy of non-toxic, natural-product resveratrol oligomers for diarrheas produced by CaCC activation. Because these compounds also inhibit the CFTR chloride channel, they may be useful for antisecretory therapy of a wide range of diarrheas.

Endothelial AMP-Activated Kinase α1 Phosphorylates eNOS on Thr495 and Decreases Endothelial NO Formation.

AMP-activated protein kinase (AMPK) is frequently reported to phosphorylate Ser1177 of the endothelial nitric-oxide synthase (eNOS), and therefore, is linked with a relaxing effect. However, previous studies failed to consistently demonstrate a major role for AMPK on eNOS-dependent relaxation. As AMPK also phosphorylates eNOS on the inhibitory Thr495 site, this study aimed to determine the role of AMPKα1 and α2 subunits in the regulation of NO-mediated vascular relaxation. Vascular reactivity to phenylephrine and acetylcholine was assessed in aortic and carotid artery segments from mice with global (AMPKα-/-) or endothelial-specific deletion (AMPKαΔEC) of the AMPKα subunits. In control and AMPKα1-depleted human umbilical vein endothelial cells, eNOS phosphorylation on Ser1177 and Thr495 was assessed after AMPK activation with thiopental or ionomycin. Global deletion of the AMPKα1 or α2 subunit in mice did not affect vascular reactivity. The endothelial-specific deletion of the AMPKα1 subunit attenuated phenylephrine-mediated contraction in an eNOS- and endothelium-dependent manner. In in vitro studies, activation of AMPK did not alter the phosphorylation of eNOS on Ser1177, but increased its phosphorylation on Thr495. Depletion of AMPKα1 in cultured human endothelial cells decreased Thr495 phosphorylation without affecting Ser1177 phosphorylation. The results of this study indicate that AMPKα1 targets the inhibitory phosphorylation Thr495 site in the calmodulin-binding domain of eNOS to attenuate basal NO production and phenylephrine-induced vasoconstriction.

Inhibition of Erythrocyte Cell Membrane Scrambling by ASP3026.

BACKGROUND/AIMS: The anaplastic lymphoma kinase (ALK) inhibitor ASP3026 is in clinical development for the treatment of ALK expressing non-small cell lung carcinoma (NSCLC). ASP3026 is in part effective by inducing apoptosis of tumor cells. Erythrocytes lack mitochondria and nuclei, key organelles in the execution of apoptosis, but are nevertheless able to enter suicidal death or eryptosis, which is characterized by cell membrane scrambling with phosphatidylserine translocation to the cell surface and by cell shrinkage. Eryptosis is triggered by cell stress, such as energy depletion, hyperosmotic shock, oxidative stress and excessive increase of cytosolic Ca2+ activity ([Ca2+]i). The present study explored, whether ASP3026 impacts on eryptosis. METHODS: Human erythrocytes have been exposed to energy depletion (glucose withdrawal for 48 hours), oxidative stress (addition of 0.3 mM tert-butylhydroperoxide [tBOOH] for 50 min) or Ca2+ loading with Ca2+ ionophore ionomycin (1 µM for 60 min) in absence and presence of ASP3026 (1-4 µg/ml). Flow cytometry was employed to quantify phosphatidylserine exposure at the cell surface from annexin-V-binding, and cell volume from forward scatter. RESULTS: Treatment with ASP3026 alone did not significantly modify annexin-V-binding or forward scatter. Energy depletion, oxidative stress and ionomycin, all markedly and significantly increased the percentage of annexin-V-binding erythrocytes, and decreased the forward scatter. ASP3026 significantly blunted the effect of energy depletion and oxidative stress, but not of ionomycin on annexin-V-binding. ASP3026 did not significantly influence the effect of any maneuver on forward scatter. CONCLUSIONS: ASP3026 is a novel inhibitor of erythrocyte cell membrane scrambling following energy depletion and oxidative stress.

Inhibition of Suicidal Erythrocyte Death by Volasertib.

BACKGROUND/AIMS: The Polo-like kinase 1 (Plk1) inhibitor volasertib is used in the treatment of malignancy. Volasertib is partially effective by triggering suicidal death or apoptosis of tumor cells. Similar to apoptosis of nucleated cells, erythrocytes may enter suicidal cell death or eryptosis, which is characterized by cell membrane scrambling with phosphatidylserine translocation to the cell surface and by cell shrinkage. Stimulators of eryptosis include energy depletion, hyperosmotic shock, oxidative stress and excessive increase of cytosolic Ca2+ activity ([Ca2+]i). The present study explored, whether volasertib impacts on eryptosis. METHODS: Human erythrocytes have been exposed to energy depletion (glucose withdrawal for 48 hours), hyperosmotic shock (addition of 550 mM sucrose for 6 hours), oxidative stress (addition of 0.3 mM tert-butylhydroperoxide [tBOOH] for 50 min) or Ca2+ ionophore ionomycin (1 µM for 60 min) in absence and presence of volasertib (0.5-1.5 µg/ml) and flow cytometry was employed to quantify phosphatidylserine exposure at the cell surface from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3 fluorescence, reactive oxygen species from 2',7'-dichlorodihydrofluorescein diacetate (DCFDA) fluorescence and ceramide abundance utilizing antibodies. For comparison, annexin-V-binding and forward scatter were determined following a 48 hours exposure of human leukemic K562 cells in RPMI-1640 medium to volasertib. RESULTS: Treatment with volasertib alone did not significantly modify annexin-V-binding or forward scatter in mature erythrocytes. Energy depletion, hyperosmotic shock, oxidative stress and ionomycin, all markedly and significantly increased the percentage of annexin-V-binding erythrocytes, and decreased the forward scatter. Volasertib significantly blunted the effect of energy depletion and hyperosmotic shock, but not of oxidative stress and ionomycin on annexin-V-binding. Volasertib did not significantly influence the effect of any maneuver on forward scatter. In K562 cells, volasertib enhanced annexin-V-binding and decreased the forward scatter. CONCLUSIONS: Volasertib is a novel inhibitor of erythrocyte cell membrane scrambling following energy depletion and hyperosmotic shock, effects contrasting the stimulation of K562 cell apoptosis.

Ionomycin induces prostaglandin E2 formation in murine osteoblastic MC3T3-E1 cells via mechanisms independent of its ionophoric nature.

Ionomycin and A23187 are divalent cation ionophores with a marked preference for calcium. Studies using these ionophores have almost exclusively interpreted their results in the light of calcium elevation. It was the aim of this study to investigate the effects of ionomycin in osteoblatic MC3T3-E1 cells that are not attributable to its ionophoric properties. Thus, we have found that in contrast to A23187, ionomycin shows similar effects on prostaglandin E2 formation as bradykinin and endothelin-1, being potentiated by extracellular nickel and inhibited by cholera toxin and pertussis toxin. Our data strongly suggest that inomycin, at least in part, exerts its effects via specific binding to a G-protein coupled receptor, thereby evoking downstream cellular events like arachidonate release with subsequent prostaglandin formation.