scholarly journals Oligomerization and Ca2+/calmodulin control binding of the ER Ca2+-sensors STIM1 and STIM2 to plasma membrane lipids

2013 ◽  
Vol 33 (5) ◽  
Author(s):  
Rajesh Bhardwaj ◽  
Hans-Michael Müller ◽  
Walter Nickel ◽  
Matthias Seedorf
Keyword(s):  
Plasma Membrane ◽  
Membrane Lipids ◽  
Lipid Binding ◽  
Dependent Manner ◽  
Activation Threshold ◽  
Concentration Dependent Manner ◽  
Rich Domain ◽  
Α Helix ◽  
Distinct Features ◽  
Ca2 Channels

Ca2+ (calcium) homoeostasis and signalling rely on physical contacts between Ca2+ sensors in the ER (endoplasmic reticulum) and Ca2+ channels in the PM (plasma membrane). STIM1 (stromal interaction molecule 1) and STIM2 Ca2+ sensors oligomerize upon Ca2+ depletion in the ER lumen, contact phosphoinositides at the PM via their cytosolic lysine (K)-rich domains, and activate Ca2+ channels. Differential sensitivities of STIM1 and STIM2 towards ER luminal Ca2+ have been studied but responses towards elevated cytosolic Ca2+ concentration and the mechanism of lipid binding remain unclear. We found that tetramerization of the STIM1 K-rich domain is necessary for efficient binding to PI(4,5)P2-containing PM-like liposomes consistent with an oligomerization-driven STIM1 activation. In contrast, dimerization of STIM2 K-rich domain was sufficient for lipid binding. Furthermore, the K-rich domain of STIM2, but not of STIM1, forms an amphipathic α-helix. These distinct features of the STIM2 K-rich domain cause an increased affinity for PI(4,5)P2, consistent with the lower activation threshold of STIM2 and a function as regulator of basal Ca2+ levels. Concomitant with higher affinity for PM lipids, binding of CaM (calmodulin) inhibited the interaction of the STIM2 K-rich domain with liposomes in a Ca2+ and PI(4,5)P2 concentration-dependent manner. Therefore we suggest that elevated cytosolic Ca2+ concentration down-regulates STIM2-mediated ER–PM contacts via CaM binding.

scholarly journals Defining how multiple lipid species interact with inward rectifier potassium (Kir2) channels

2020 ◽  
Vol 117 (14) ◽  
pp. 7803-7813 ◽  
Author(s):  
Anna L. Duncan ◽  
Robin A. Corey ◽  
Mark S. P. Sansom
Keyword(s):  
Plasma Membrane ◽  
Membrane Lipids ◽  
Membrane Lipid ◽  
Inward Rectifier ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Anionic Lipid ◽  
Lipid Interactions ◽  
Interaction Sites ◽  
Lipid Species

Protein–lipid interactions are a key element of the function of many integral membrane proteins. These potential interactions should be considered alongside the complexity and diversity of membrane lipid composition. Inward rectifier potassium channel (Kir) Kir2.2 has multiple interactions with plasma membrane lipids: Phosphatidylinositol (4, 5)-bisphosphate (PIP2) activates the channel; a secondary anionic lipid site has been identified, which augments the activation by PIP2; and cholesterol inhibits the channel. Molecular dynamics simulations are used to characterize in molecular detail the protein–lipid interactions of Kir2.2 in a model of the complex plasma membrane. Kir2.2 has been simulated with multiple, functionally important lipid species. From our simulations we show that PIP2interacts most tightly at the crystallographic interaction sites, outcompeting other lipid species at this site. Phosphatidylserine (PS) interacts at the previously identified secondary anionic lipid interaction site, in a PIP2concentration-dependent manner. There is interplay between these anionic lipids: PS interactions are diminished when PIP2is not present in the membrane, underlining the need to consider multiple lipid species when investigating protein–lipid interactions.

Differential blockade of agonist- and depolarization-induced 45Ca2+ influx in smooth muscle cells

1989 ◽  
Vol 257 (4) ◽  
pp. C607-C611 ◽  
Author(s):  
A. Wallnofer ◽  
C. Cauvin ◽  
T. W. Lategan ◽  
U. T. Ruegg
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Aortic Smooth Muscle Cells ◽  
Aortic Smooth Muscle ◽  
Gamma S ◽  
Ca2 Channels ◽  
Stimulation Of

ATP stimulated 45Ca2+ influx in rat aortic smooth muscle cells in a concentration-dependent manner (EC50 = 3.6 +/- 0.5 X 10(-7) M). ADP and GTP were less effective than ATP in stimulating 45Ca2+ influx; AMP was weakly active and the adenosine agonist 5'-(N-ethyl-carboxamido)-adenosine (NECA) had no effect. ATP gamma S was about equieffective with ATP, whereas alpha,beta-methylene-ATP (APCPP) did not induce 45Ca2+ influx. Stimulation of 45Ca2+ influx by ATP was not abolished by the dihydropyridine Ca2+ channel antagonist darodipine (PY 108-068), which completely blocked depolarization-induced 45Ca2+ influx. Inorganic cations (La3+, Cd2+, Co2+, Ni2+, Mn2+, and Mg2+) were able to inhibit both agonist- and depolarization-induced 45Ca2+ influx. Cd2+, however, was approximately 20 times more selective in blocking K+-stimulated than agonist-stimulated 45Ca2+ influx. These data indicate that ATP-stimulated Ca2+ influx in rat aortic smooth muscle cells is resistant to darodipine but is reduced by La3+, Cd2+, and other inorganic blockers of Ca2+ channels.

Endothelin activation of phospholipase D: dual modulation by protein kinase C and Ca2+

1993 ◽  
Vol 264 (5) ◽  
pp. F845-F853
Author(s):  
M. M. Friedlaender ◽  
D. Jain ◽  
Z. Ahmed ◽  
D. Hart ◽  
R. L. Barnett ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phospholipase D ◽  
Intracellular Signaling ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Kinase C ◽  
Eta Receptor ◽  
Ca2 Channels ◽  
Stimulation Of

Previous work from this laboratory has identified an endothelin (ET) type A (ETA) receptor on cultured rat renal medullary interstitial cells (RMIC), coupled to phosphatidylinositol-specific phospholipase C (PI-PLC), dihydropyridine-insensitive receptor-operated Ca2+ channels, and phospholipase A2. The current studies explored a role for ET stimulation of phosphatidylcholine-specific phospholipase D (PC-PLD) in intracellular signaling of this cell type. ET stimulated PLD activation, as measured by phosphatidic acid (PA) or phosphatidylethanol (PEt) accumulation, in a time- and concentration-dependent manner. Inhibition of diacylglycerol (DAG) kinase by ethylene glycol dioctanoate or 6-(2)4-[(4-fluorophenyl)-phenylmethylene]-1-piperadinyl]ethy l-7-methyl-5H - thiaxolo-[3,2-alpyrimidin]-5-one (R 59022) failed to blunt PA accumulation, indicating that PLD, and not DAG, was the source of PA. Inhibition of PA phosphohydrolase (PAP) by propranolol increased late accumulation of PA, suggesting that the prevailing metabolic flow was in the direction of PA to DAG. Phorbol 12-myristate 13-acetate (PMA) augmented ET-evoked PEt accumulation, whereas downregulation of protein kinase C (PKC) obviated agonist-induced PEt production. PMA augmentation of PLD activity proceeded independent of cytosolic free Ca2+ concentration. Ca2+ derived from either intracellular or extracellular sources enhanced ET-related PEt accumulation but was without effect in PKC-downregulated cells. Collectively, these observations indicate that ET stimulates PLD production in RMIC. PKC is the major regulator of this process, with Ca2+ playing a secondary, modulatory role. In addition, these data suggest that PC-PLD is coupled to the ETA receptor.

Inhibition of Na+/Ca2+ exchange in renal BLMV by IP3 depends on site of action and direction of Ca2+ flux

1994 ◽  
Vol 266 (5) ◽  
pp. F785-F790 ◽  
Author(s):  
C. L. Fraser ◽  
C. Cummings ◽  
G. Cassafer
Keyword(s):  
Plasma Membrane ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Dependent Manner ◽  
The Novel ◽  
Concentration Dependent Manner ◽  
Site Of Action ◽  
Brain Synaptosomes ◽  
Membrane Bound ◽  
Inside Out

It has previously been shown in synaptosomes that inositol 1,4,5-trisphosphate (1,4,5-IP3) inhibits Ca2+ transport by the plasma membrane-bound Na+/Ca2+ exchanger. The present study was therefore designed to determine if the effect of 1,4,5-IP3 was dependent on its site of action at the plasma membrane or on the direction of Ca2+ flux. To investigate this possibility, studies were performed in basolateral membrane vesicles (BLMV) isolated from rat renal cortex. As with synaptosomes, Ca2+ transport was inhibited by 1,4,5-IP3 in a concentration-dependent manner. At a concentration of 10(-6) M, 1,4,5-IP3 significantly (P < 0.005) inhibited Ca2+ transport by 36%. When Ca2+ transport was carried out in inside-out vesicles, 10(-6) M 1,4,5-IP3 significantly (P < 0.002) increased the degree of inhibition by an additional 75% (63 vs. 36%). However, 1,4,5-IP3 had no significant effect on Ca2+ transport in inside-out vesicles when Ca2+ flux was reversed (i.e., Ca2+ efflux). These data in renal BLMV confirm the novel action of 1,4,5-IP3 on the Na+/Ca2+ exchanger previously described in brain synaptosomes. These results also suggest that the action of 1,4,5-IP3 depends on both its site of action at the plasma membrane and on the direction of Ca2+ flux.

scholarly journals Molecular basis for coupling the plasma membrane to the actin cytoskeleton during clathrin-mediated endocytosis

2012 ◽  
Vol 109 (38) ◽  
pp. E2533-E2542 ◽  
Author(s):  
Michal Skruzny ◽  
Thorsten Brach ◽  
Rodolfo Ciuffa ◽  
Sofia Rybina ◽  
Malte Wachsmuth ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Actin Cytoskeleton ◽  
Actin Filaments ◽  
Lipid Binding ◽  
Actin Binding ◽  
Dependent Manner ◽  
Vesicle Budding ◽  
Cooperative Action ◽  
Binding Domains ◽  
Membrane Invagination

Dynamic actin filaments are a crucial component of clathrin-mediated endocytosis when endocytic proteins cannot supply enough energy for vesicle budding. Actin cytoskeleton is thought to provide force for membrane invagination or vesicle scission, but how this force is transmitted to the plasma membrane is not understood. Here we describe the molecular mechanism of plasma membrane–actin cytoskeleton coupling mediated by cooperative action of epsin Ent1 and the HIP1R homolog Sla2 in yeast Saccharomyces cerevisiae. Sla2 anchors Ent1 to a stable endocytic coat by an unforeseen interaction between Sla2’s ANTH and Ent1’s ENTH lipid-binding domains. The ANTH and ENTH domains bind each other in a ligand-dependent manner to provide critical anchoring of both proteins to the membrane. The C-terminal parts of Ent1 and Sla2 bind redundantly to actin filaments via a previously unknown phospho-regulated actin-binding domain in Ent1 and the THATCH domain in Sla2. By the synergistic binding to the membrane and redundant interaction with actin, Ent1 and Sla2 form an essential molecular linker that transmits the force generated by the actin cytoskeleton to the plasma membrane, leading to membrane invagination and vesicle budding.

scholarly journals Regulation of the electrogenic H+ channel in the plasma membrane of neutrophils: possible role of phospholipase A2, internal and external protons

1993 ◽  
Vol 292 (2) ◽  
pp. 445-450 ◽  
Author(s):  
A Kapus ◽  
K Suszták ◽  
E Ligeti
Keyword(s):  
Plasma Membrane ◽  
Phospholipase A2 ◽  
Neutrophil Granulocytes ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Conducting Pathway ◽  
External Ph ◽  
Force Relationship ◽  
Stimulation Of

Possible factors regulating the opening of and the rate of H+ flux through a recently described, Cd(2+)-sensitive, phorbol ester- and arachidonic acid (AA)-activatable H(+)-conducting pathway in the plasma membrane of neutrophil granulocytes were investigated. (1) The phospholipase A2 blocker p-bromophenacyl bromide (BPB) inhibited the phorbol 12-myristate 13-acetate (PMA)-induced activation of this channel in a concentration-dependent manner (IC50, 4 microM). (2) Neither BPB nor the protein kinase C (PKC) inhibitor staurosporine influenced the AA-elicited stimulation of this route. (3) Intracellular acidification (cytoplasmic pH below 6.9) itself is capable of activating an electrogenic, Cd(2+)-sensitive H+ efflux indicating that protons can open up this route in the absence of any other stimulator. (4) PMA significantly decreases the intracellular H+ concentration ([H+]i) threshold for the opening of the channel, thus providing a conductive state at resting pH values, and elevates the rate of H+ efflux at any [H+]i. (5) Changes in external pH also modify the operation of the channel: above an extracellular pH (pH(o)) value of 7.4, the H(+)-flux/driving force relationship is approx. 5-fold greater than below this value. Our results suggest a multifactorial regulation of the electrogenic H+ channel: most probably PKC activates the channel indirectly, via stimulation of phospholipase A2 that subsequently liberates AA. In addition to this, the channel conductance seems to be promoted by internal H+ and inhibited by external H+.

scholarly journals Relaxant mechanism of Eulophia macrobulbon ethanolic extract and 1-(4΄-hydroxybenzyl)-4, 8-dimethoxyphenanthrene-2,7-diol on human corpus cavernosum

2019 ◽  
Vol 9 (5) ◽  
pp. 328
Author(s):  
Chaweewan Jansakul ◽  
Somreudee Yorsin ◽  
Jomkarn Naphatthalung ◽  
Kuldej Tachanaparugse ◽  
Kanokwan Changwichai ◽  
...  
Keyword(s):  
Erectile Dysfunction ◽  
Pde5 Inhibitor ◽  
Corpus Cavernosum ◽  
Ethanolic Extract ◽  
Good Choice ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Relaxant Effect ◽  
Phosphodiesterase 5 ◽  
Ca2 Channels

Background: Eulophia macrobulbon (E.C.Parish & Rchb.f.) Hook.F. has been shown to be a promising phosphodiesterase-5 (PDE5) inhibitor that relaxes rat isolated pulmonary artery.Objective: To test this plant’s possible application in human erectile dysfunction (ED) using an ethanolic extract of E. macrobulbon tubers (EM extract), and an isolated constituent, 1-(4΄-hydroxybenzyl)-4, 8-dimethoxyphenanthrene-2,7-diol (HDP).Methods: Dried tubers of EM were extracted with 95% ethanol and the HDP was isolated by several chromatographic methods. The relaxant mechanism of the EM extract and the HDP was studied on isolated human cavernosal strips (HC strip).Results: EM extract (0.1-3 mg/ml) relaxed HC strips precontracted with phenylephrine. The relaxant effect was not modified by N-nitro-L-arginine (L-NNA), ODQ, tetraethylammonium, nor glybenclamide. HDP (0.1-3 mM) relaxed HC strips precontracted with phenylephrine to the same extent as that of sildenafil. EM extract and HDP potentiated relaxation of the HC strips to glyceryl trinitrate in a similar manner to that of sildenafil. EM extract and sildenafil, but not HDP, increased cGMP content of the HC strips in a concentration-dependent manner. In the thapsigargin-pretreated HC strips, nifedipine or EM extract, but not HDP, suppressed the contractile response of the HC strips to phenylephrine. When nifedipine and/or SKF 96365 (stored-operated Ca2+ channel blocker) was added, followed by EM extract or HDP, further suppression was found in the case of HDP but not with EM extract. Ca2+ free Krebs solution suppressed the phenylephrine contraction on HC strips and further suppression was found when adding EM extract or HDP.Conclusion: These results indicate that EM extract causes a relaxation of HC strips by serving as an inhibitor of PDE5, of voltage- and stored-operated Ca2+ channels, and of intracellular Ca2+ mobilization. Thus EM extract might be a good choice for development as a functional food for erectile dysfunction in men. However, further studies are needed to identify other PDE5 and the Ca2+channel inhibiting components of the extract.

scholarly journals Effects of dexmedetomidine on porcine pulmonary artery vascular smooth muscle

2019 ◽  
Author(s):  
Mami Chikuda ◽  
Kenichi Sato
Keyword(s):  
Smooth Muscle ◽  
Pulmonary Artery ◽  
Vascular Smooth Muscle ◽  
Local Anesthetics ◽  
Pulmonary Arteries ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Duration Of Action ◽  
Porcine Pulmonary Artery ◽  
Ca2 Channels

Abstract Background Dexmedetomidine is added to local anesthetics to increase their potency and extend their duration of action, thus providing postoperative analgesia with a single administration. However, the effects and mechanism of action of dexmedetomidine on pulmonary arteries have not been determined. The aim of this study was to investigate the effect of dexmedetomidine on pulmonary artery vascular smooth muscle, evaluating changes in contraction tension. Methods Endothelium-denuded porcine pulmonary arteries were sliced into 2- to 3-mm rings. Changes in isometric contraction tension were measured with the addition of various substances at various concentrations, under different conditions of baseline stimulation (with KCl, Adrenaline, caffeine, or histamine) and different conditions of Ca2+ depletion with intracellular reservoirs or extracellular stores depleted. Results Dexmedetomidine increased the contraction tension induced by high-KCl depolarization in a concentration-dependent manner. Dexmedetomidine inhibited receptor-activated Ca2+ channels (RACCs) and phosphatidylinositol-1,4,5-triphosphate-induced Ca2+ release (IICR), but not Ca2+-induced Ca2+ release (CICR). Conclusions Dex increased the contraction tension resulting from depolarization stimulation by high KCl in a concentration-dependent manner in porcine pulmonary artery vascular smooth muscle. The enhancement of high KCl-induced contraction with Dex addition was mediated by α2 receptors. Dex suppressed increases in contraction tension induced by receptor stimulation with adrenaline, also in a concentration-dependent manner. Dex inhibited RACC and IICR, but not CICR. Elucidating the effects and mechanisms of action of Dex in the central arteries is likely to be useful as basic data for creating Dex-containing local anesthetics.

Inhibition of Maize (Zea mays L.) Root Plasma Membrane-Bound Redox Activities by Coumarins

1994 ◽  
Vol 49 (7-8) ◽  
pp. 447-452 ◽  
Author(s):  
Sabine Lüthje ◽  
José A. Gonzaléz-Reyes ◽  
Placido Navas ◽  
Olaf Döring ◽  
Michael Böttger
Keyword(s):  
Zea Mays ◽  
Plasma Membrane ◽  
Zea Mays L ◽  
Membrane Vesicles ◽  
Dependent Manner ◽  
Plasma Membrane Vesicles ◽  
Two Phase ◽  
Concentration Dependent Manner ◽  
Oxidoreductase Activity ◽  
Membrane Bound

Modulation of plasma membrane-bound NADH:hexacyanoferrate III oxidoreductase activities by dicumarol and warfarin was investigated with plasma membrane vesicles of Zea mays L. (cv. Sil Anjou 18) roots, prepared by aqueous two phase partitioning. Vesicles were about 65% right-side out orientated as demonstrated by enzyme latency of vanadate sensitive ATPase activity. Dicumarol or warfarin, respectively, inhibited NADH:hexacyanoferrate III oxidoreductase activity in a concentration-dependent manner and inhibition could be reversed partially by addition of quinones

Effect of digitonin on rat myometrium subcellular membrane fractions

1981 ◽  
Vol 59 (11) ◽  
pp. 1128-1133 ◽  
Author(s):  
A. K. Grover ◽  
C. Y. Kwan ◽  
J. Crankshaw ◽  
E. E. Daniel
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Cytochrome C ◽  
Plasma Membranes ◽  
Dependent Manner ◽  
Mitochondrial Marker ◽  
Concentration Dependent Manner ◽  
Subcellular Membrane ◽  
Ca Uptake ◽  
Isopycnic Centrifugation

Isopycnic centrifugation experiments using sucrose density gradients showed that in digitonin-treated microsomes the distribution of the plasma membrane (PM) marker 5′-nucleotidase was shifted to higher densities. The treatment also caused similar but less pronounced changes in the distribution of protein, the putative endoplasmic reticulum (ER) marker NADPH-dependent cytochrome c reductase, and the inner mitochondrial marker cytochrome c oxidase. Similar experiments using more purified membrane fractions showed that the digitonin treatment led to a comparable increase in the densities of the fractions N1 and N2 previously described as subfractions of plasma membrane and to considerably less increase in the density of the fraction N3B which is enriched in the endoplasmic reticulum and the inner mitochondrial markers. Digitonin inhibited the ATP-dependent Ca uptake by the N1 fraction in a concentration-dependent manner (I50 = 0.3 mg/mL). Digitonin (0.5 mg/mL) inhibited the ATP-dependent azide-insensitive Ca uptake by all the fractions. The results support the hypothesis that (a) N1 and N2 are subfractions of plasma membrane, and (b) ATP-dependent azide-insensitive Ca uptake in rat myometrium is a property of plasma membranes.

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