Inhibition of TASK-1 potassium channel by phospholipase C

2001 ◽  
Vol 281 (2) ◽  
pp. C700-C708 ◽  
Author(s):  
Gábor Czirják ◽  
Gábor L. Petheő ◽  
András Spät ◽  
Péter Enyedi
Keyword(s):  
Phospholipase C ◽  
Lysophosphatidic Acid ◽  
Protein S ◽  
Receptor Activation ◽  
Xenopus Laevis Oocytes ◽  
Ang Ii ◽  
Inositol 1,4,5 Trisphosphate ◽  
Glomerulosa Cells ◽  
Pore Domain ◽  
Stimulation Of

The two-pore-domain K+ channel, TASK-1, was recently shown to be a target of receptor-mediated regulation in neurons and in adrenal glomerulosa cells. Here, we demonstrate that TASK-1 expressed in Xenopus laevis oocytes is inhibited by different Ca2+-mobilizing agonists. Lysophosphatidic acid, via its endogenous receptor, and ANG II and carbachol, via their heterologously expressed ANG II type 1a and M1 muscarinic receptors, respectively, inhibit TASK-1. This effect can be mimicked by guanosine 5′- O-(3-thiotriphosphate), indicating the involvement of GTP-binding protein(s). The phospholipase C inhibitor U-73122 reduced the receptor-mediated inhibition of TASK-1. Downstream signals of phospholipase C action (inositol 1,4,5-trisphosphate, cytoplasmic Ca2+ concentration, and diacylglycerol) do not mediate the inhibition. Unlike the Gq-coupled receptors, stimulation of the Gi-activating M2 muscarinic receptor coexpressed with TASK-1 results in an only minimal decrease of the TASK-1 current. However, additional coexpression of phospholipase C-β2 (which is responsive also to Giβγ-subunits) renders M2 receptor activation effective. This indicates the significance of phospholipase C activity in the receptor-mediated inhibition of TASK-1.

Modulation of phospholipase C pathway and level of Gq alpha/G11 alpha in rat myometrium during gestation

1996 ◽  
Vol 271 (3) ◽  
pp. C895-C904 ◽  
Author(s):  
S. Lajat ◽  
Z. Tanfin ◽  
G. Guillon ◽  
S. Harbon
Keyword(s):  
Phospholipase C ◽  
G Proteins ◽  
Pertussis Toxin ◽  
Inositol Phosphates ◽  
Receptor Activation ◽  
Similar Increase ◽  
Inositol 1,4,5 Trisphosphate ◽  
M3 Subtype ◽  
Subtype A ◽  
Stimulation Of

The regulation of the receptor-G protein-phospholipase C (PLC) cascade was investigated in rat myometrium at midgestation (day 12) and at term (day 21) comparatively to the estrogen-treated tissue (day 0). Carbachol-mediated generation of [3H]inositol phosphates was insensitive to pertussis toxin and was enhanced at days 12 and 21 two- and threefold, respectively, with no alteration of muscarinic sites (M3 subtype). A similar increase could be detected in the production of inositol 1,4,5-trisphosphate, indicating the stimulation of a PLC degrading phosphatidylinositol 4,5-bisphosphate. AlF4- also enhanced PLC activation during gestation, suggesting pregnancy-related regulations that bypass receptor activation. Immunoreactive G proteins, Gq alpha and G11 alpha, and PLC-beta 3 were detected in all myometrial preparations. The amount of PLC-beta 3 was similar in day 0 and day 21 myometrium, although decreasing by 75% at midgestation. Of significance was the increased amount of Gq alpha in day 12 and day 21 myometrium (3- and 2-fold, respectively) which coincided with the enhanced phosphoinositide breakdown. The upregulation of Gq alpha may contribute to the enhanced PLC activity during pregnancy and at term.

scholarly journals The role of calmodulin-binding sites in the regulation of the Drosophila TRPL cation channel expressed in Xenopus laevis oocytes by Ca2+, inositol 1,4,5-trisphosphate and GTP-binding proteins

1998 ◽  
Vol 330 (3) ◽  
pp. 1149-1158 ◽  
Author(s):  
Ling LAN ◽  
Helen BRERETON ◽  
J. Greg BARRITT
Keyword(s):  
Binding Sites ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Protein S ◽  
Tryptophan Residue ◽  
Xenopus Laevis Oocytes ◽  
Calmodulin Binding ◽  
Gtp Binding ◽  
Inositol 1,4,5 Trisphosphate ◽  
Stimulation Of

The roles of calmodulin-binding sites in the regulation by Ca2+, inositol 1,4,5-trisphosphate (InsP3) and GTP-binding regulatory proteins (G-proteins) of the Drosophila melanogaster TRPL (transient-receptor-potential-like) non-specific Ca2+ channel were investigated. Wild-type TRPL protein and two mutant forms, TRPL (W713G) and TRPL (W814G), in which a key tryptophan residue in each of the two putative calmodulin-binding sites (Sites 1 and 2, respectively) was replaced by glycine, were expressed heterologously in Xenopuslaevis oocytes. Immunofluorescence studies indicated that the expressed TRPL, TRPL (W713G) and TRPL (W814G) proteins are located at the plasma membrane. TRPL oocytes (oocytes injected with trpl cRNA) and TRPL (W814G) oocytes [oocytes injected with trpl (W814G) cRNA] exhibited substantially greater rates of basal (constitutive) Ca2+ inflow (measured using fluo-3 and the Ca2+ add-back protocol) than mock-injected oocytes (mock oocytes). In TRPL (W713G) oocytes, this difference was abolished. In TRPL and TRPL (W814G) [oocytes injected with trpl (W713G) cRNA], but not in TRPL (W713G) oocytes, basal Ca2+ inflow was inhibited by W13, an inhibitor of calmodulin action. Calmodulin (3 μM intracellular) inhibited basal Ca2+ inflow in TRPL but not in TRPL (W713G) or TRPL (W814G) oocytes. Staurosporin, an inhibitor of protein kinase C (PKC), inhibited, while PMA (an activator of PKC) stimulated, basal Ca2+ inflow in TRPL oocytes. In oocytes incubated in the presence of PMA (to suppress Ca2+ inflow through endogenous receptor-activated Ca2+ channels), the InsP3-induced stimulation of Ca2+ inflow through TRPL channels was more clearly evident than in oocytes incubated in the absence of PMA. InsP3 caused a significant stimulation of Mn2+ inflow in TRPL but not in mock oocytes. Rates of InsP3-stimulated Ca2+ inflow through the TRPL, TRPL (W713G) and TRPL (W814G) channels were similar. The ability of GTPγS to stimulate Ca2+ inflow through TRPL channels was inhibited by 50% in TRPL (W713G) oocytes but was unaffected in TRPL (W814G) oocytes. It is concluded that, in the environment of the Xenopus oocyte, the Drosophila TRPL channel is activated by (a) interaction with Ca2+/calmodulin at calmodulin-binding Site 1; (b) PKC; (c) InsP3 in a process that does not involve Ca2+ and calmodulin; and (d) a trimeric G-protein(s) through both a Ca2+/calmodulin-dependent and a Ca2+/calmodulin-independent mechanism.

ANG II AT2 receptor modulates AT1receptor-mediated descending vasa recta endothelial Ca2+ signaling

2003 ◽  
Vol 284 (3) ◽  
pp. H779-H789 ◽  
Author(s):  
Kristie Rhinehart ◽  
Corey A. Handelsman ◽  
Erik P. Silldorff ◽  
Thomas L. Pallone
Keyword(s):  
Receptor Agonist ◽  
Calcium Concentration ◽  
Cyclopiazonic Acid ◽  
Receptor Activation ◽  
Receptor Subtype ◽  
Ang Ii ◽  
Receptor Stimulation ◽  
Vasa Recta ◽  
Stimulation Of

We tested whether the respective angiotensin type 1 (AT1) and 2 (AT2) receptor subtype antagonists losartan and PD-123319 could block the descending vasa recta (DVR) endothelial intracellular calcium concentration ([Ca2+]i) suppression induced by ANG II. ANG II partially reversed the increase in [Ca2+]igenerated by cyclopiazonic acid (CPA; 10−5 M), acetylcholine (ACh; 10−5 M), or bradykinin (BK; 10−7 M). Losartan (10−5 M) blocked that effect. When vessels were treated with ANG II before stimulation with BK and ACh, concomitant AT2 receptor blockade with PD-123319 (10−8 M) augmented the suppression of endothelial [Ca2+]i responses. Similarly, preactivation with the AT2 receptor agonist CGP-42112A (10−8 M) prevented AT1 receptor stimulation with ANG II + PD-123319 from suppressing endothelial [Ca2+]i. In contrast to endothelial [Ca2+]i suppression by ANG II, pericyte [Ca2+]i exhibited typical peak and plateau [Ca2+]i responses that were blocked by losartan but not PD-123319. DVR vasoconstriction by ANG II was augmented when AT2 receptors were blocked with PD-123319. Similarly, AT2 receptor stimulation with CGP-42112A delayed the onset of ANG II-induced constriction. PD-123319 alone (10−5 M) showed no AT1-like action to constrict microperfused DVR or increase pericyte [Ca2+]i. We conclude that ANG II suppression of endothelial [Ca2+]i and stimulation of pericyte [Ca2+]i is mediated by AT1 or AT1-like receptors. Furthermore, AT2 receptor activation opposes ANG II-induced endothelial [Ca2+]i suppression and abrogates ANG II-induced DVR vasoconstriction.

Mobilization of Intracellular Calcium by Methacholine and Inositol 1,4,5-Trisphosphate in Rat Parotid Acinar Cells

1987 ◽  
Vol 66 (2) ◽  
pp. 547-551 ◽  
Author(s):  
D.L. Aub ◽  
J.W. Putney
Keyword(s):  
Receptor Activation ◽  
Transient Phase ◽  
Cell Preparation ◽  
Similar Concentration ◽  
Parotid Acinar Cells ◽  
Parotid Acinar Cell ◽  
Inositol 1,4,5 Trisphosphate ◽  
Intracellular Ca ◽  
Rat Parotid ◽  
Stimulation Of

In the rat parotid acinar cell, methacholine caused an increase in [Ca2+]i as determined by quin-2 fluorescence. The increase in [Ca2+] i was initially independent of, and subsequently dependent on, the presence of extracellular Ca2+, indicating mobilization of intracellular Ca2+, as well as activation of Ca2+ entry. Methacholine mobilization of the internal Ca2+ pool and stimulation of the initial transient phase of K+ efflux have similar concentration dependencies; the EC50 value for Ca2+ mobilization is 80 nmollL, the EC50 value for K+ efflux is 200 nmol/L. In a permeable parotid cell preparation, inositol 1,4,5-trisphosphate, inositol 2,4,5-trisphosphate, and inositol 4,5-bisphosphate were able to release Ca2+ from an ATP-dependent, oligomycininsensitive pool. These observations, when taken with the previous finding that methacholine stimulates Ca-independent inositol trisphosphate formation, support the view that inositol 1,4,5-trisphosphate acts as a second messenger mediating the release of an intracellular Ca 2+ pool following muscarinic receptor activation in the parotid gland.

scholarly journals The NHERF1 PDZ1 domain and IRBIT interact and mediate the activation of Na+/H+ exchanger 3 by ANG II

2016 ◽  
Vol 311 (2) ◽  
pp. F343-F351 ◽  
Author(s):  
Peijian He ◽  
Luqing Zhao ◽  
Yi Ran No ◽  
Serhan Karvar ◽  
C. Chris Yun
Keyword(s):  
Proximal Tubule ◽  
Fluorescent Protein ◽  
Cultured Cells ◽  
Yellow Fluorescent Protein ◽  
Protein S ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Ang Ii ◽  
Renal Brush Border Membrane ◽  
Inositol 1,4,5 Trisphosphate

Na+/H+ exchanger (NHE)3, a major Na+ transporter in the luminal membrane of the proximal tubule, is subject to ANG II regulation in renal Na+/fluid absorption and blood pressure control. We have previously shown that inositol 1,4,5-trisphosphate receptor-binding protein released with inositol 1,4,5-trisphosphate (IRBIT) mediates ANG II-induced exocytosis of NHE3 in cultured proximal tubule epithelial cells. In searching for scaffold protein(s) that coordinates with IRBIT in NHE3 trafficking, we found that NHE regulatory factor (NHERF)1, NHE3, and IRBIT proteins were coexpressed in the same macrocomplexes and that loss of ANG II type 1 receptors decreased their expression in the renal brush-border membrane. We found that NHERF1 was required for ANG II-mediated forward trafficking and activation of NHE3 in cultured cells. ANG II induced a concomitant increase of NHERF1 interactions with NHE3 and IRBIT, which were abolished when the NHERF1 PDZ1 domain was removed. Overexpression of a yellow fluorescent protein-NHERF1 construct that lacks PDZ1, but not PDZ2, failed to exaggerate the ANG II-dependent increase of NHE3 expression in the apical membrane. Moreover, exogenous expression of PDZ1 exerted a dominant negative effect on NHE3 activation by ANG II. We further demonstrated that IRBIT was indispensable for the ANG II-provoked increase in NHERF1-NHE3 interactions and that phosphorylation of IRBIT at Ser68 was necessary for the assembly of the NHEF1-IRBIT-NHE3 complex. Taken together, our findings suggest that NHERF1 mediates ANG II-induced activation of renal NHE3, which requires coordination between IRBIT and the NHERF1 PDZ1 domain in binding and transporting NHE3.

scholarly journals Enhanced purinoceptor-mediated Ca2+ signalling in L-fibroblasts overexpressing type 1 inositol 1,4,5-trisphosphate receptors

1999 ◽  
Vol 341 (3) ◽  
pp. 813-820 ◽  
Author(s):  
Richard J. DAVIS ◽  
R. A. John CHALLISS ◽  
Stefan R. NAHORSKI
Keyword(s):  
Direct Evidence ◽  
Protein S ◽  
Fibroblast Cells ◽  
Similar Concentration ◽  
Cell Clones ◽  
Fold Reduction ◽  
Inositol 1,4,5 Trisphosphate ◽  
Functional Consequences ◽  
Stimulation Of

Mouse L-fibroblast cells stably transfected with either type 1 Ins(1,4,5)P3 receptor (InsP3R) cDNA (L15) or the vector control (Lvec) have been used to investigate the functional consequences of increased InsP3R density on receptor-mediated Ca2+ signalling. L15 cells express approx. 8-fold higher levels of the type 1 InsP3R compared with Lvec cells, which endogenously express essentially only the type 1 InsP3R protein. Stimulation of Lvec and L15 cells with UTP or ATP increased cytosolic Ca2+ concentration to a greater extent in L15 cells at all agonist concentrations. UTP and ATP were equipotent, suggestive of the presence of endogenous cell-surface metabotropic P2Y2-purinoceptors. In both cell clones the purinoceptors were coupled via pertussis-toxin-insensitive G-protein(s) to phospholipase C activation, resulting in similar concentration-dependent accumulations of InsP3. Single-cell microfluorimetry revealed that overexpression of InsP3Rs reduced the threshold for purinoceptor-mediated Ca2+ signalling. L-fibroblasts also exhibited temporally complex sinusoidal cytosolic Ca2+ oscillations in response to submaximal agonist concentrations, with significant increases in oscillatory frequencies exhibited by cells overexpressing InsP3Rs. Sustainable oscillatory responses were dependent on Ca2+ entry and, at higher agonist concentrations, cytosolic Ca2+ oscillations were superseded by biphasic peak-and-plateau Ca2+ responses. Overexpression of InsP3Rs in L15 cells resulted in a 4-fold reduction in the threshold for this change in the temporal pattern of Ca2+ mobilization. These data provide the first direct evidence demonstrating that altering the expression of the type 1 InsP3R significantly affects receptor-mediated InsP3-induced Ca2+ mobilization.

Mechanisms of ET-1 potentiation of angiotensin II stimulation of aldosterone production

1993 ◽  
Vol 265 (2) ◽  
pp. E179-E183 ◽  
Author(s):  
E. N. Cozza ◽  
C. E. Gomez-Sanchez
Keyword(s):  
Angiotensin Ii ◽  
Zona Glomerulosa ◽  
Ang Ii ◽  
Aldosterone Secretion ◽  
Direct Stimulation ◽  
Potentiation Effect ◽  
Aldosterone Production ◽  
Glomerulosa Cells ◽  
Pkc Inhibitors ◽  
Stimulation Of

Endothelin-1 (ET-1) exerts the following two types of aldosterone-stimulating actions on glomerulosa cells: ET-1-mediated direct stimulation of aldosterone secretion (per se effect) and potentiation of the aldosterone secretion to angiotensin II (ANG II; potentiation effect). The role of Ca2+ and protein kinase C (PKC) systems in these two effects was investigated. Incubations of calf cultured adrenal zona glomerulosa cells in low-Ca2+ media or in the presence of the Ca2+ channel antagonist verapamil reduced the aldosterone secretion to ET-1. When cells were preincubated with ET-1 in a low-Ca2+ media or in the presence of the Ca2+ channel antagonist verapamil, washed, and incubated in media with normal Ca2+, ANG II showed potentiation of ANG II-stimulated aldosterone secretion. The PKC inhibitors H-7 and staurosporine did not decrease ET-1-stimulated aldosterone secretion, but they inhibited the potentiation effect of ET-1 on ANG II-mediated aldosterone secretion. Adrenocorticotropic hormone desensitization or prolonged phorbol ester stimulation of PKC resulting in desensitization also resulted in the abolition of the ET-1-mediated ANG II potentiation of aldosterone secretion. The PKC inhibitors did not affect ANG II-stimulated aldosterone secretion. We conclude that ET-1 exerts a direct stimulation of aldosterone secretion through a mechanism dependent on Ca2+ and potentiates ANG II-mediated aldosterone stimulation through a mechanism involving PKC.

scholarly journals Agonist-Induced Phosphorylation of the Endogenous AT1 Angiotensin Receptor in Bovine Adrenal Glomerulosa Cells

1998 ◽  
Vol 12 (5) ◽  
pp. 634-644 ◽  
Author(s):  
Roger D. Smith ◽  
Albert J. Baukal ◽  
Annamaria Zolyomi ◽  
Zsuzsanna Gaborik ◽  
Laszlo Hunyady ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Receptor Activation ◽  
Zona Glomerulosa ◽  
Target Cells ◽  
Ang Ii ◽  
Kinase C ◽  
Glomerulosa Cells ◽  
At1a Receptor ◽  
G Protein Coupled

Abstract A polyclonal antibody was raised in rabbits against a fusion protein immunogen consisting of bacterial maltose-binding protein coupled to a 92-amino acid C-terminal fragment of the rat AT1b angiotensin II (Ang II) receptor. The antibody immunoprecipitated the photoaffinity-labeled bovine AT1 receptor (AT1-R), but not the rat AT2 receptor, and specifically stained bovine adrenal glomerulosa cells and AT1a receptor-expressing Cos-7 cells, as well as the rat adrenal zona glomerulosa and renal glomeruli. The antibody was employed to analyze Ang II-induced phosphorylation of the endogenous AT1-R immunoprecipitated from cultured bovine adrenal glomerulosa cells. Receptor phosphorylation was rapid, sustained for up to 60 min, and enhanced by pretreatment of the cells with okadaic acid. Its magnitude was correlated with the degree of ligand occupancy of the receptor. Activation of protein kinase A and protein kinase C (PKC) also caused phosphorylation of the receptor, but to a lesser extent than Ang II. Inhibition of PKC by staurosporine augmented Ang II-stimulated AT1-R phosphorylation, suggesting a negative regulatory role of PKC on the putative G protein-coupled receptor kinase(s) that mediates the majority of AT1-R phosphorylation. The antibody should permit further analysis of endogenous AT1-R phosphorylation in Ang II target cells.

scholarly journals Measurement of perimitochondrial Ca2+ concentration in bovine adrenal glomerulosa cells with aequorin targeted to the outer mitochondrial membrane

1999 ◽  
Vol 341 (3) ◽  
pp. 745-753 ◽  
Author(s):  
Yves BRANDENBURGER ◽  
Jean-François ARRIGHI ◽  
Michel F. ROSSIER ◽  
Andrès MATURANA ◽  
Michel B. VALLOTTON ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Mitochondrial Membrane ◽  
Proteinase K ◽  
Outer Mitochondrial Membrane ◽  
Mitochondrial Matrix ◽  
Ang Ii ◽  
Peak Response ◽  
Strong Gradient ◽  
Glomerulosa Cells ◽  
Stimulation Of

Microdomains of high cytosolic free Ca2+ concentration in the proximity of mitochondria might have an important role in the stimulation of steroidogenesis in bovine adrenal glomerulosa cells. In the present study we have investigated local changes of free Ca2+ concentration near the outer mitochondrial membrane ([Ca2+]om) under stimulation with angiotensin II (Ang II) and K+. Glomerulosa cells in primary culture were transfected with a recombinant cDNA encoding the N-terminal region of the human translocase protein 20 of the outer mitochondrial membrane, in frame with the Ca2+-sensitive photoprotein aequorin. This chimaeric aequorin (TomAeq) was associated with mitochondria-enriched subcellular fractions of transfected COS-7 cells and was susceptible to proteinase K, showing that it was targeted to the outer mitochondrial membrane, facing the cytosolic space. In bovine adrenal glomerulosa cells transfected with TomAeq cDNA, Ang II induced a transient [Ca2+]om peak reaching 1.42±0.28 μM, which decreased immediately to the basal resting value. The peak response to Ang II was strikingly lower than the peak response of mitochondrial free Ca2+ concentration, which increased to 5.4±1.2 μM. The smaller response of [Ca2+]om to Ang II compared with the elevated matrix response did not result from buffering effects of the organelle, from altered mechanisms of intramitochondrial Ca2+ transport or from differences in the affinity of the chimaeric aequorins for Ca2+. This approach has allowed us to follow perimitochondrial Ca2+ homeostasis in bovine glomerulosa cells under stimulation with Ca2+-mobilizing agonists and to reveal a strong gradient of Ca2+ concentration between the mitochondrial matrix and the immediate environment of the organelle.

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