A Previously Unrecognized Ca2+-inhibited Nonselective Cation Channel in Red Blood Cells.
Ontology highlight
ABSTRACT:
SUBMITTER: Petkova-Kirova P
PROVIDER: S-EPMC6407795 | biostudies-literature | 2018 Oct
REPOSITORIES: biostudies-literature
Publications
A Previously Unrecognized Ca<sup>2+</sup>-inhibited Nonselective Cation Channel in Red Blood Cells.
Petkova-Kirova Polina P Hertz Laura L Makhro Asya A Danielczok Jens J Huisjes Rick R Llaudet-Planas Esther E Mañú-Pereira Maria Del Mar MDM Vives Corrons Joan-Luis JL van Wijk Richard R Bogdanova Anna A Kaestner Lars L
HemaSphere 20181002 5
Supplemental Digital Content is available in the text. ...[more]
Similar Datasets
Project description:G-protein-coupled receptors (GPCRs) are a ubiquitously expressed family of receptor proteins that regulate many physiological functions and other proteins. They act through two dissociable signaling pathways: the exchange of GDP to GTP by linked G-proteins and the recruitment of β-arrestins. GPCRs modulate several members of the transient receptor potential (TRP) channel family of nonselective cation channels. How TRP channels reciprocally regulate GPCR signaling is less well-explored. Here, using an array of biochemical approaches, including immunoprecipitation and fluorescence, calcium imaging, phosphate radiolabeling, and a β-arrestin-dependent luciferase assay, we characterize a GPCR-TRP channel pair, angiotensin II receptor type 1 (AT1R), and transient receptor potential vanilloid 4 (TRPV4), in primary murine choroid plexus epithelial cells and immortalized cell lines. We found that AT1R and TRPV4 are binding partners and that activation of AT1R by angiotensin II (ANGII) elicits β-arrestin-dependent inhibition and internalization of TRPV4. Activating TRPV4 with endogenous and synthetic agonists inhibited angiotensin II-mediated G-protein-associated second messenger accumulation, AT1R receptor phosphorylation, and β-arrestin recruitment. We also noted that TRPV4 inhibits AT1R phosphorylation by activating the calcium-activated phosphatase calcineurin in a Ca2+/calmodulin-dependent manner, preventing β-arrestin recruitment and receptor internalization. These findings suggest that when TRP channels and GPCRs are co-expressed in the same tissues, many of these channels can inhibit GPCR desensitization.
| S-EPMC7380189 | biostudies-literature
Project description:Hydrogen peroxide (H2O2) released by neutrophils is an important mediator of endothelial cell (EC) injury and vascular inflammation via its effect on EC-free Ca2+, [Ca2+]i. Although the underlying mechanisms are not well understood, platelet endothelial cell adhesion molecule (PECAM)-1/CD-31 is a critical modulator of neutrophil-EC transmigration. PECAM-1 is also known to regulate EC calcium signals and to undergo selective tyrosine phosphorylation. Here, we report that PECAM-1 molecules transduce EC responses to hydrogen peroxide. In human umbilical vein EC and REN cells (a PECAM-1-negative EC-like cell line) stably transfected with PECAM-1 (RHP), noncytolytic H2O2 exposure (100-200 microM H2O2) activated a calcium-permeant, nonselective cation current, and a transient rise in [Ca2+]i of similar time course. Neither response was observed in untransfected REN cells, and H2O2-evoked cation current was ablated in REN cells transfected with PECAM-1 constructs mutated in the cytoplasmic tyrosine-containing domain. The PECAM-dependent H2O2 current was inhibited by dialysis of anti-PECAM-1 cytoplasmic domain antibodies, required Src family tyrosine kinase activity, was independent of inositol trisphosphate receptor activation, and required only an intact PECAM-1 cytoplasmic domain. PECAM-1-dependent H2O2 currents and associated [Ca2+]i transients may play a significant role in regulating neutrophil-endothelial interaction, as well as in oxidant-mediated endothelial response and injury.
| S-EPMC2173260 | biostudies-literature
Project description:Reactive oxygen species (ROS) modulator 1 (Romo1) is a nuclear-encoded mitochondrial inner membrane protein known to regulate mitochondrial ROS production and to act as an essential redox sensor in mitochondrial dynamics. Although its physiological roles have been studied for a decade, the biophysical mechanisms that explain these activities of Romo1 are unclear. In this study, we report that Romo1 is a unique mitochondrial ion channel that differs from currently identified eukaryotic ion channels. Romo1 is a highly conserved protein with structural features of class II viroporins, which are virus-encoded nonselective cation channels. Indeed, Romo1 forms a nonselective cation channel with its amphipathic helical transmembrane domain necessary for pore-forming activity. Notably, channel activity was specifically inhibited by Fe2+ ions, an essential transition metal ion in ROS metabolism. Using structural bioinformatics, we designed an experimental data-guided structural model of Romo1 with a rational hexameric structure. We propose that Romo1 establishes a new category of viroporin-like nonselective cation channel in eukaryotes.
| S-EPMC5987721 | biostudies-literature
Project description:The NaK channel is a cation-selective protein with similar permeability for K(+) and Na(+) ions. Crystallographic structures are available for the wild-type and mutated NaK channels with different numbers of cation-binding sites. We have performed a comparison between the potentials of mean force governing the translocation of K(+) ions and mixtures of one Na(+) and three K(+) ions in a mutated NaK channel with only three cation-binding sites (NaK-CNG). Since NaK-CNG is not selective for K(+) over Na(+), analysis of its multi-ion potential energy surfaces can provide clues about how selectivity originates. Comparison of the potentials of mean force of NaK-CNG and K(+)-selective channels yields observations that strongly suggest that the number of contiguous ion binding sites in a single-file mechanism is the key determinant of the channel's selectivity properties, as already proposed by experimental studies. We conclude that the presence of four binding sites in K(+)-selective channels is essential for highly selective and efficient permeation of K(+) ions, and that a key difference between K(+)-selective and nonselective channels is the absence/presence of a binding site for Na(+) ions at the boundary between S2 and S3 in the context of multi-ion permeation events.
| S-EPMC3512044 | biostudies-literature
Project description:Dendritic cell (DC) maturation and migration are events critical for the initiation of immune responses. After encountering pathogens, DCs upregulate the expression of costimulatory molecules and subsequently migrate to secondary lymphoid organs. Calcium (Ca(2+)) entry governs the functions of many hematopoietic cell types, but the role of Ca(2+) entry in DC biology remains unclear. Here we report that the Ca(2+)-activated nonselective cation channel TRPM4 was expressed in and controlled the Ca(2+) homeostasis of mouse DCs. The absence of TRPM4, which elicited Ca(2+) overload, did not influence DC maturation but did considerably impair chemokine-dependent DC migration. Our results establish TRPM4-regulated Ca(2+) homeostasis as crucial for DC mobility but not maturation and emphasize that DC maturation and migration are independently regulated.
| S-EPMC2956271 | biostudies-literature
Project description:Collapse of membrane lipid asymmetry is a hallmark of blood coagulation. TMEM16F of the TMEM16 family that includes TMEM16A/B Ca(2+)-activated Cl(-) channels (CaCCs) is linked to Scott syndrome with deficient Ca(2+)-dependent lipid scrambling. We generated TMEM16F knockout mice that exhibit bleeding defects and protection in an arterial thrombosis model associated with platelet deficiency in Ca(2+)-dependent phosphatidylserine exposure and procoagulant activity and lack a Ca(2+)-activated cation current in the platelet precursor megakaryocytes. Heterologous expression of TMEM16F generates a small-conductance Ca(2+)-activated nonselective cation (SCAN) current with subpicosiemens single-channel conductance rather than a CaCC. TMEM16F-SCAN channels permeate both monovalent and divalent cations, including Ca(2+), and exhibit synergistic gating by Ca(2+) and voltage. We further pinpointed a residue in the putative pore region important for the cation versus anion selectivity of TMEM16F-SCAN and TMEM16A-CaCC channels. This study thus identifies a Ca(2+)-activated channel permeable to Ca(2+) and critical for Ca(2+)-dependent scramblase activity during blood coagulation. PAPERFLICK:
| S-EPMC3582364 | biostudies-literature
Project description:Maitotoxin (MTX) activates Ca(2+)-permeable nonselective cation channels and causes a dramatic increase in cytosolic free Ca(2+) concentration ([Ca(2+)](i)) in every cell examined to date, but the molecular identity of the channels involved remains unknown. A clue came from studies of a structurally related marine toxin called palytoxin (PTX). PTX binds to the plasmalemmal Na(+)-K(+)-ATPase (NKA) and converts the Na(+) pump into a nonselective cation channel. Given the high permeability of the MTX channel for Ca(2+), we considered the possibility that MTX may bind to the plasmalemmal Ca(2+)-ATPase (PMCA) pump, and like PTX, convert the pump into a channel. To test this hypothesis, the PMCA was overexpressed in Spodoptera frugiperda (Sf9) insect cells and in human embryonic kidneys (HEK) 293 cells. In both cell types, enhanced expression of the PMCA was associated with a significant increase in MTX-induced whole cell membrane currents. The effect of MTX on whole cell currents in both wild-type and PMCA overexpressing HEK cells was sensitive to pump ligands including Ca(2+) and ATP. MTX-induced currents were significantly reduced by knockdown of PMCA1 in HEK cells using small interfering RNA or in mouse embryonic fibroblasts from genetically modified mice with the PMCA1(+/-) PMCA4(-/-) genotype. Finally, PMCA catalytic activity (i.e., Ca(2+)-ATPase) in isolated membranes, or in purified PMCA preparations, was inhibited by MTX. Together, these results suggest that MTX binds to and converts the PMCA pump into a Ca(2+)-permeable nonselective cation channel.
| S-EPMC2793065 | biostudies-literature
Project description:Apical nonselective cation channels with an average single-channel conductance of 34 +/- 2.3 pS were found in M-1 mouse cortical collecting duct cells. Channel activity is increased by depolarization and abolished by cytoplasmic calcium removal. Cytoplasmic application of 0.1 mM cGMP decreases channel open probability by 27%. cDNAs corresponding to approximately 40% of the coding region of the photoreceptor channel were isolated by the polymerase chain reaction from M-1 cells and a rat kidney cDNA library. The rat kidney-derived sequence differs by a single base, and the M-1-cell-derived sequence differs by only two bases, from the photoreceptor sequence. A second clone from M-1 cells differs by 20 out of 426 bases from the photoreceptor sequence. In all three clones, the deduced amino acid sequence is identical to that of the rat photoreceptor channel. Northern blot analysis of poly(A)+ RNA from M-1 cells reveals the presence of a 3.2-kilobase band hybridizing with a retinal cGMP-gated cation channel probe. The results suggest the expression in M-1 cells of more than one gene coding for nonselective cation channels or channel subunits, one of which is identical to the cGMP-gated cation channel gene of rod photoreceptors.
| S-EPMC50318 | biostudies-other
Project description:Lipopolysaccharide (LPS) has been implicated in sepsis-mediated heart failure and chronic cardiac myopathies. We determined that LPS directly and reversibly affects cardiac myocyte function by altering regulation of intracellular Ca2+ concentration ([Ca2+]i) in immortalized cardiomyocytes, HL-1 cells. [Ca2+]i oscillated (<0.4 Hz), displaying slow and transient components. LPS (1 microg/ml), derived either from Escherichia coli or from Salmonella enteritidis, reversibly abolished Ca2+ oscillations and decreased basal [Ca2+]i by 30-40 nM. HL-1 cells expressed Toll-like receptors, i.e., TLR-2 and TLR-4. Thus, we differentiated effects of LPS on [Ca2+]i and Ca2+ oscillations by addition of utlrapure LPS, a TLR-4 ligand. Ultrapure LPS had no effect on basal [Ca2+]i, but it reduced the rate of Ca2+ oscillations. Interestingly, Pam3CSK4, a TLR-2 ligand, affected neither Ca2+ parameter, and the effect of ultrapure LPS and Pam3CSK4 combined was similar to that of utlrapure LPS alone. Thus, unpurified LPS directly inhibits HL-1 calcium metabolism via TLR-4 and non-TLR-4-dependent mechanisms. Since others have shown that endotoxin impairs the hyperpolarization-activated, nonselective cationic pacemaker current (I(f)), which is expressed in HL-1 cells, we utilized whole cell voltage-clamp techniques to demonstrate that LPS (1 microg/ml) reduced I(f) in HL-1 cells. This inhibition was marginal at physiologic membrane potentials and significant at very negative potentials (P < 0.05 at -140, -150, and -160 mV). So, we also evaluated effects of LPS on tail currents of fully activated I(f). LPS reduced the slope conductance of the tail currents from 498 +/- 140 pS/pF to 223 +/- 65 pS/pF (P < 0.05) without affecting reversal potential of -11 mV. Ultrapure LPS had similar effect on I(f), whereas Pam3CSK4 had no effect on I(f). We conclude that LPS inhibits activation of I(f), enhances its deactivation, and impairs regulation of [Ca2+]i in HL-1 cardiomyocytes via TLR-4 and other mechanisms.
| S-EPMC2944324 | biostudies-literature
Project description:Under static conditions, mammalian red blood cells (RBCs) require a continuous supply of energy, typically via glucose, to maintain their biconcave disc shape. Mechanical distortion, in a complementary way, should lead to increased energy demand that is manifest in accelerated glycolysis. The experimental challenge in observing this phenomenon was met by reversibly and reproducibly distorting the cells and noninvasively measuring glycolytic flux. This was done with a gel-distorting device that was coupled with 13C nuclear magnetic resonance (NMR) spectroscopy. We measured [3-13C]l-lactate production from [1,6-13C]d-glucose in the RBCs suspended in gelatin gels, and up to 90% rate enhancements were recorded. Thus, for the first time, we present experiments that demonstrate the linkage of mechanical distortion to metabolic changes in whole mammalian cells. In seeking a mechanism for the linkage between shape and energy supply, we measured transmembrane cation flux with Cs+ (as a K+ congener) using 133Cs NMR spectroscopy, and the cation flux was increased up to fivefold. The postulated mechanism for these notable (in terms of whole-body energy consumption) responses is stimulation of Ca-adenosine triphosphatase by increased transmembrane flux of Ca2+ via the channel protein Piezo1 and increased glycolysis because its flux is adenosine triphosphate demand-regulated.
| S-EPMC5647125 | biostudies-other