scholarly journals Different calcium-dependent pathways control fertilisation-triggered glycoside release and the cortical contraction in ascidian eggs

Zygote ◽  
1995 ◽  
Vol 3 (3) ◽  
pp. 251-258 ◽  
Author(s):  
Alex McDougall ◽  
Christian Sardet ◽  
Charles. C Lambert
Keyword(s):  
Intracellular Calcium ◽  
Sea Water ◽  
Calcium Influx ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Acetoxymethyl Ester ◽  
Calcium Dependent ◽  
Sperm Binding ◽  
Calcium Requirement ◽  
A Cell

SummaryFertilisation of ascidian eggs induces the rapid release of a cell surface N-acetylglycosaminidase that blocks sperm binding to vitelline coat sperm receptors resulting in a block to polyspermy. Fertilisation also triggers a large contraction of the egg (thus stimulating ooplasmic segregation) that is completed within 5 min of insemination. In eggs of the ascidian Phallusia mammillata, glycosidase release and cortical contractions are blocked by BAPTA-AM [bis-(o-aminophenoxy-ethane-N,N,N',N' -tetraacetic acid, tetra(acetoxymethyl)-ester], a cell-permeant calcium chelator, indicating that both processes are probaly dependent on a rise in intracellular calcium levels. Both glycosidase release and the cortical contraction are induced by treatment of the egg with the protein synthesis inhibitor emetine, while only the glycosidase release is induced by isoproterenol, carbachol or acetylcholine. Previous work with ryanodine demonstrated that ryanodine also caused glycosidase release but not the cortical contraction Inversely, activation by ionomycin in calcium-free sea water causes cortical contractions but not glycosidase release. Thus the two processes can be activated independently. Dextran-coupled (10kDa) calcium green-1 injected eggs show an increase in intracellular calcium 30–40s before the cortical contraction is triggered by fertilisation or ionomycin- induced activation. This confirms previous findings that the cortical contraction is a consequence of the activation calcium the triggered by te sperm. The extracellular calcium requirement for the glycosidase release suggests that calcium influx may be more important for this phase of egg activation. Thus activation eggs appears to involve two independent pathways involving calcium.

scholarly journals Glucocorticoids acutely increase cell surface Na+/H+ exchanger-3 (NHE3) by activation of NHE3 exocytosis

2005 ◽  
Vol 289 (4) ◽  
pp. F685-F691 ◽  
Author(s):  
I. Alexandru Bobulescu ◽  
Vangipuram Dwarakanath ◽  
Lixian Zou ◽  
Jianning Zhang ◽  
Michel Baum ◽  
...  
Keyword(s):  
Cell Surface ◽  
Cell Model ◽  
Protein Synthesis Inhibitor ◽  
Transcriptional Level ◽  
Protein Abundance ◽  
Synthesis Inhibitor ◽  
Opossum Kidney ◽  
Proximal Tubular ◽  
A Cell ◽  
Exchange Activity

Glucocorticoids have important effects on renal function, including the modulation of renal acidification by the major proximal tubular Na+/H+ exchanger, NHE3. While the chronic effect of glucocorticoids is considered to be primarily at the transcriptional level, with increases in NHE3 mRNA and protein expression driving increased transport activity, the mechanisms by which glucocorticoids activate NHE3 in an acute setting have not been investigated. Previous studies have shown that a glucocorticoid-stimulated increase in NHE3 activity can occur before any detectable change in NHE3 mRNA. The present study examines the acute effects of glucocorticoids on NHE3 using opossum kidney (OKP) cells as a cell model. In OKP cells, total NHE3 protein abundance was not changed by 3 h of treatment with dexamethasone (10−6 M). However, the biotin-accessible fraction representing NHE3 at the apical membrane as well as Na+/H+ exchange activity measured fluorimetrically using the pH-sensitive dye BCECF-AM were significantly increased. These effects were not prevented by the protein synthesis inhibitor cycloheximide. NHE3 insertion (biotinylatable NHE3 after sulfo-NHS-acetate blockade) was stimulated by dexamethasone incubation, with or without cycloheximide. The rate of NHE3 endocytic retrieval, assessed either by the avidin protection assay (early endocytosis) or by the sodium 2-mercaptoethane sulfonate (MesNa) cleavage assay (early and late endocytosis), was not affected by dexamethasone. These findings suggest that trafficking plays a key role in the acute stimulation of NHE3 by glucocorticoids, with exocytosis being the major contributor to the glucocorticoid-induced rapid increase in cell surface NHE3 protein abundance and Na+/H+ exchange activity.

Calcium-dependent regulation of cation transport in cultured human nonpigmented ciliary epithelial cells

1993 ◽  
Vol 264 (3) ◽  
pp. C519-C526 ◽  
Author(s):  
T. Mito ◽  
N. A. Delamere ◽  
M. Coca-Prados
Keyword(s):  
Potassium Channels ◽  
Intracellular Calcium ◽  
Ciliary Epithelium ◽  
Established Cell Line ◽  
Acetoxymethyl Ester ◽  
Calcium Dependent ◽  
Calcium Buffer ◽  
Established Cell ◽  
External Potassium ◽  
Stimulation Of

We performed 86Rb flux studies to examine Na-K-adenosinetriphosphatase (ATPase), Na-K-2Cl cotransporter, and potassium channel activity in an established cell line derived from human nonpigmented ciliary epithelium (ODM2). The elevation of intracellular calcium by A23187 (3 microM) or thapsigargin (200 nM) increased both ouabain-sensitive potassium (86Rb) uptake (Na-K-ATPase mediated) and ouabain-insensitive potassium (86Rb) uptake. The ouabain-insensitive component could be inhibited substantially by bumetanide (0.1 mM), suggesting the involvement of a Na-K-2Cl cotransporter. The increase of potassium (86Rb) uptake caused by thapsigargin could be prevented by the intracellular calcium buffer 1,2-bis(2-amino-phenoxy)ethane N,N,N',N'-tetraacetic acetoxymethyl ester (BAPTA/AM); in BAPTA/AM-treated cells, the thapsigargin stimulation of the bumetanide-sensitive portion of 86Rb uptake was abolished. After A23187 (5 microM), the 86Rb efflux rate was significantly increased; the increase could be blocked partially by quinidine (0.1 mM) and partially by bumetanide, suggesting that potassium channels and the Na-K-2Cl cotransporter contribute to the effect. We propose that the cell potassium loss after activation of quinidine-sensitive potassium channels is involved in the calcium-induced activation of Na-K-ATPase because 0.1 mM quinidine and 100 mM external potassium both markedly inhibited the A23187-induced increases of the ouabain-sensitive component of potassium (86Rb) uptake. Calcium-induced stimulation of the Na-K-2Cl cotransporter may not be linked to channel activation.

scholarly journals Sperm binding and fertilization envelope formation in a cell surface complex isolated from sea urchin eggs.

1979 ◽  
Vol 81 (1) ◽  
pp. 92-103 ◽  
Author(s):  
G L Decker ◽  
W J Lennarz
Keyword(s):  
Sea Water ◽  
Secretory Vesicles ◽  
Surface Complex ◽  
Surface Complexes ◽  
Exterior Surface ◽  
Thin Sections ◽  
Sperm Binding ◽  
Specific Manner ◽  
A Cell ◽  
Species Specific

An isolated surface complex consisting of the vitelline layer, plasma membrane, and attached secretory vesicles has been examined for its ability to bind sperm and to form the fertilization envelope. Isolated surface complexes (or intact eggs) fixed in glutaraldehyde and then washed in artificial sea water are capable of binding sperm in a species-specific manner. Sperm which bind to the isolated surface complex exhibit the acrosomal process only when they are associated with the exterior surface (vitelline layer) of the complex. Upon resuspension of the unfixed surface complex in artificial sea water, a limiting envelope is formed which, based on examination of thin sections and negatively stained surface preparations, is structurally similar to the fertilization envelope formed by the fertilized egg. These results suggest that the isolated egg surface complex retains the sperm receptor, as well as integrated functions for the secretion of components involved in assembly of the fertilization envelope.

Urea signaling to ERK phosphorylation in renal medullary cells requires extracellular calcium but not calcium entry

2001 ◽  
Vol 280 (1) ◽  
pp. F162-F171 ◽  
Author(s):  
Xiao-Yan Yang ◽  
Hongyu Zhao ◽  
Zheng Zhang ◽  
Karin D. Rodland ◽  
Jean-Baptiste Roullet ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Calcium Release ◽  
Calcium Entry ◽  
Extracellular Calcium ◽  
Urea Treatment ◽  
Erk Activation ◽  
Calcium Dependent ◽  
Erk Phosphorylation ◽  
Extracellular Signal ◽  
A Cell

The renal cell line mIMCD3 exhibits markedly upregulated phosphorylation of the extracellular signal-regulated kinase (ERK) 1 and 2 in response to urea treatment (200 mM for 5 min). Previous data have suggested the involvement of a classical protein kinase C (cPKC)-dependent pathway in downstream events related to urea signaling. We now show that urea-inducible ERK activation requires extracellular calcium; unexpectedly, it occurs independently of activation of cPKC isoforms. Pharmacological inhibitors of known intracellular calcium release pathways and extracellular calcium entry pathways fail to inhibit ERK activation by urea. Fura 2 ratiometry was used to assess the effect of urea treatment on intracellular calcium mobilization. In single-cell analyses using subconfluent monolayers and in population-wide analyses using both confluent monolayers and cells in suspension, urea failed to increase intracellular calcium concentration. Taken together, these data indicate that urea-inducible ERK activation requires calcium action but not calcium entry. Although direct evidence is lacking, one possible explanation could include involvement of a calcium-dependent extracellular moiety of a cell surface-associated protein.

scholarly journals Listeriolysin O-Dependent Bacterial Entry into the Cytoplasm Is Required for Calpain Activation and Interleukin-1α Secretion in Macrophages Infected with Listeria monocytogenes

2010 ◽  
Vol 78 (5) ◽  
pp. 1884-1894 ◽  
Author(s):  
Sita R. Dewamitta ◽  
Takamasa Nomura ◽  
Ikuo Kawamura ◽  
Hideki Hara ◽  
Kohsuke Tsuchiya ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Intracellular Calcium ◽  
Mutant Strain ◽  
Calcium Influx ◽  
Cytolytic Activity ◽  
Calpain Inhibitor ◽  
Listeriolysin O ◽  
Wild Type ◽  
Calcium Dependent ◽  
Interleukin 1Α

ABSTRACT Listeriolysin O (LLO), an hly-encoded cytolysin of Listeria monocytogenes, plays an essential role in the entry of L. monocytogenes into the host cell cytoplasm. L. monocytogenes-infected macrophages produce various proinflammatory cytokines, including interleukin-1α (IL-1α), that contribute to the host immune response. In this study, we have examined IL-1α production in macrophages infected with wild-type L. monocytogenes or a nonescaping mutant strain deficient for LLO (Δhly). Expression of IL-1α mRNA and accumulation of pro-IL-1α in the cytoplasm were induced by both strains. In contrast, the secretion of the mature form of IL-1α from infected macrophages was observed in infection with wild-type L. monocytogenes but not with the Δhly mutant. A recovery of the ability to induce IL-1α secretion was shown in a mutant strain complemented with the hly gene. The Toll-like receptor (TLR)/MyD88 signaling pathway was exclusively required for the expression of pro-IL-1α, independently of LLO-mediated cytoplasmic entry of L. monocytogenes. The LLO-dependent secretion of mature IL-1α was abolished by addition of calcium chelators, and only LLO-producing L. monocytogenes strains were able to induce elevation of the intracellular calcium level in infected macrophages. A calcium-dependent protease, calpain, was implicated in the maturation and secretion of IL-1α induced by LLO-producing L. monocytogenes strains based on the effect of calpain inhibitor. Functional activation of calpain was detected in macrophages infected with LLO-producing L. monocytogenes strains but not with a mutant strain lacking LLO. These results clearly indicated that LLO-mediated cytoplasmic entry of bacteria could induce the activation of intracellular calcium signaling, which is essential for maturation and secretion of IL-1α in macrophages during L. monocytogenes infection through activation of a calcium-dependent calpain protease. In addition, recombinant LLO, when added to macrophages infected with the Δhly strain, could induce calcium influx and IL-1α secretion at doses exhibiting cytolytic activity, suggesting that LLO produced by intracellular L. monocytogenes may be implicated in induction of calcium influx through pore formation.

scholarly journals The interdependence of endothelin-1 and calcium: a review

2010 ◽  
Vol 119 (9) ◽  
pp. 361-372 ◽  
Author(s):  
Nathan R. Tykocki ◽  
Stephanie W. Watts
Keyword(s):  
Intracellular Calcium ◽  
Calcium Concentration ◽  
Calcium Influx ◽  
Calcium Signalling ◽  
Intracellular Calcium Concentration ◽  
Future Research ◽  
Endothelin 1 ◽  
Calcium Dependent ◽  
Amino Acid Peptide ◽  
Physiological Processes

The 21-amino-acid peptide ET-1 (endothelin-1) regulates a diverse array of physiological processes, including vasoconstriction, angiogenesis, nociception and cell proliferation. Most of the effects of ET-1 are associated with an increase in intracellular calcium concentration. The calcium influx and mobilization pathways activated by ET-1, however, vary immensely. The present review begins with the basics of calcium signalling and investigates the different ways intracellular calcium concentration can increase in response to a stimulus. The focus then shifts to ET-1, and discusses how ET receptors mobilize calcium. We also examine how disease alters calcium-dependent responses to ET-1 by discussing changes to ET-1-mediated calcium signalling in hypertension, as there is significant interest in the role of ET-1 in this important disease. A list of unanswered questions regarding ET-mediated calcium signals are also presented, as well as perspectives for future research of calcium mobilization by ET-1.

scholarly journals Expression and possible involvement of calpain isoforms in mammalian egg activation

Reproduction ◽  
2005 ◽  
Vol 130 (2) ◽  
pp. 165-175 ◽  
Author(s):  
Irit Ben-Aharon ◽  
Karin Haim ◽  
Ruth Shalgi ◽  
Dalit Ben-Yosef
Keyword(s):  
Intracellular Calcium ◽  
Cysteine Proteases ◽  
Meiotic Spindle ◽  
Egg Activation ◽  
Activation Process ◽  
Calcium Dependent ◽  
Sperm Binding ◽  
Cellular Events

At fertilization in mammals, the spermatozoon triggers a unique signal transduction mechanism within the egg, leading to its activation. It is well accepted that the earliest event observed in all activated eggs is an abrupt rise in intracellular calcium concentrations. However, little is known regarding the downstream proteins that are activated by this rise in calcium. Calpains constitute a family of intracellular calcium-dependent cysteine proteases whose members are expressed widely in a variety of cells. We investigated the expression and possible role of the calpain isoforms μ and m throughout egg activation. Both calpains were expressed in the rat egg and localized at the egg cortex as well as in the meiotic spindle. m Calpain translocated to the membrane and to the spindle area during parthenogenetic egg activation and duringin vivofertilization, upon sperm binding to the egg. The cytoskeletal protein α-spectrin (fodrin) was proteolysed by calpain during the egg-activation process, as demonstrated by specific calpain-breakdown products. Following parthenogenetic activation by ionomycin or puromycin, the calpain-selective permeable inhibitor, calpeptin, inhibited the resumption of meiosis and cortical reaction in a dosedependent manner. Calpeptin was also effective in inhibitingin vitrofertilization. These results may imply a correlation between calpain activation and mammalian egg activation at fertilization and a possible role for calpain in the cascade of cellular events leading to resumption of meiosis.

Control of ascorbic acid efflux in rat luteal cells: role of intracellular calcium and oxygen radicals

2003 ◽  
Vol 285 (3) ◽  
pp. C642-C651 ◽  
Author(s):  
John R. Pepperell ◽  
D. Marshall Porterfield ◽  
David L. Keefe ◽  
Harold R. Behrman ◽  
Peter J. S. Smith
Keyword(s):  
Ascorbic Acid ◽  
Intracellular Calcium ◽  
Calcium Influx ◽  
Single Cells ◽  
Calcium Ionophore ◽  
Extracellular Calcium ◽  
Luteal Cells ◽  
Calcium Dependent ◽  
Intracellular Ros ◽  
Dichlorofluorescein Diacetate

In luteal cells, prostaglandin (PG)F2a mobilizes intracellular calcium concentration ([Ca]i), generates reactive oxygen species (ROS), depletes ascorbic acid (AA) levels, inhibits steroidogenesis, and ultimately induces cell death. We investigated the hypothesis that [Ca]i mobilization stimulates ROS, which results in depletion of cellular AA in rat luteal cells. We used a self-referencing AA-selective electrode that noninvasively measures AA flux at the extended boundary layer of single cells and fluorescence microscopy with fura 2 and dichlorofluorescein diacetate (DCF-DA) to measure [Ca]i and ROS, respectively. Menadione, a generator of intracellular superoxide radical ([Formula: see text]), PGF2a, and calcium ionophore were shown to increase [Ca]i and stimulate intracellular ROS. With calcium ionophore and PGF2a, but not menadione, the generation of ROS was dependent on extracellular calcium influx. In unstimulated cells there was a net efflux of AA of 121.5 ± 20.3 fmol · cm–1 · s–1 (mean ± SE, n = 8), but in the absence of extracellular calcium the efflux was significantly reduced (10.3 ± 4.9 fmol · cm–1 · s–1; n = 5, P < 0.05). PGF2a and menadione stimulated AA efflux, but calcium ionophore had no significant effect. These data suggest two AA regulatory mechanisms: Under basal conditions, AA efflux is calcium dependent and may represent recycling and maintenance of an antioxidant AA gradient at the plasma membrane. Under luteolytic hormone and/or oxidative stress, AA efflux is stimulated that is independent of extracellular calcium influx or generation of ROS. Although site-specific mobilization of calcium pools and ROS cannot be ruled out, the release of AA by PGF2a-stimulated luteal cells may occur through other signaling pathways.

Presence of P2X1 Purinoceptors in Human Platelets and Megakaryoblastic Cell Lines

1997 ◽  
Vol 78 (06) ◽  
pp. 1500-1504 ◽  
Author(s):  
Catherine Vial ◽  
Béatrice Hechier ◽  
Catherine Léon ◽  
Jean-Pierre Cazenave ◽  
Christian Gachet
Keyword(s):  
Intracellular Calcium ◽  
G Proteins ◽  
Cell Lines ◽  
Calcium Influx ◽  
Human Platelets ◽  
P2y1 Receptor ◽  
Calcium Response ◽  
Ionotropic Receptors ◽  
External Calcium

SummaryHuman platelets are thought to possess at least two subtypes of purinoceptor, one of which, coupled to G-proteins, could be the P2Y1 receptor (Léon et al. 1997). However, it has been suggested that the unique rapid calcium influx induced by ADP in platelets could involve P2X1 ionotropic receptors (MacKenzie et al. 1996) and the aim of this study was thus to investigate the presence of P2X purinoceptors in platelets and megakaryoblastic cells. Using PCR experiments, we found P2X1 mRNA to be present in human platelets and megakaryoblastic cell lines. In platelets, the selective P2X1 agonist αβMeATP induced a rise in intracellular calcium only in the presence of external calcium and this effect was antagonized by suramin and PPADS. Repeated addition of a�MeATP desensitized the P2X1 purinoceptor but only slightly affected the ADP response, while no calcium response to αβMeATP was observed in megakaryoblastic cells. These results support the existence of functional P2X1 purinoceptors on human platelets and the presence of P2X1 transcripts in megakaryoblastic cell lines.

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