scholarly journals Follicle-Stimulating Hormone-Induced Gαh/Phospholipase C-δ1 Signaling Mediating a Noncapacitative Ca2+ Influx through T-Type Ca2+ Channels in Rat Sertoli Cells

Endocrinology ◽  
2007 ◽  
Vol 149 (3) ◽  
pp. 1031-1037 ◽  
Author(s):  
Tsung-Hsuan Lai ◽  
Yuan-Feng Lin ◽  
Feng-Chang Wu ◽  
Yu-Hui Tsai
Keyword(s):  
Phospholipase C ◽  
Sertoli Cells ◽  
Synthetic Peptide ◽  
Calcium Release ◽  
Channel Blocker ◽  
Follicle Stimulating Hormone ◽  
Fold Increase ◽  
Selective Inhibitor ◽  
Free Media ◽  
Ca2 Channels

Our previous study demonstrated that FSH-induced immediate Ca2+ influx in rat Sertoli cells (SCs) is mediated by the Gαh/phospholipase C-δ1 (PLC-δ1) signaling pathway. As to which Ca2+ channel is responsible for such Ca2+ influx was not understood. In this study, thapsigargin triggered an in-store calcium release and evoked a 1.5-fold elevation of intracellular Ca2+ in Ca2+-free media, whereas FSH exhibited no effect. The readdition of CaCl2 (2.5 mm) to FSH-pretreated or thapsigargin-sensitized SCs in Ca2+-free media immediately elicited a rapid Ca2+ influx or a 2-fold increase of second intracellular Ca2+ elevation, respectively. The addition of Ca2+ chelator EGTA (0.2 mm) reduced the FSH-induced elevation of intracellular Ca2+ in SCs incubated with CaCl2. However, pretreatment with dantrolene (25 μM), which inhibits in-store calcium release, did not affect the FSH-induced elevation of intracellular Ca2+. NiCl2 (10 μM), a T-type calcium channel blocker, abolished the FSH-induced SC Ca2+ influx. Furthermore, mibefradil (10 and 100 μm), another specific blocker for T-type Ca2+ channels, dose-dependently suppressed the FSH-induced Ca2+ influx. In contrast, nifedipine (10 and 50 μm) or ω-conotoxin GVIA (100 and 500 nm), blocker of L- or N-type Ca2+ channels, respectively, did not affect the FSH-induced SC Ca2+ influx. On the other hand, FSH-induced Ca2+ influx was significantly reduced by pretreatment of SCs with myristoylated synthetic peptide (0.1 and 1 μm) of PLC-δ1 fragment TIPWNSLKQGYRHVHLL but not affected by 2′,5′-dideoxyadenosine (3 and 15 μm), a selective inhibitor of adenylate cyclase. In conclusion, the FSH-induced Gαh/PLC-δ1 pathway-dependent Ca2+ influx of rat SCs is mediated by T-type Ca2+ channels and independent of in-store calcium release.

Gelsolin — evidence for a role in turnover of junction-related actin filaments in Sertoli cells

2002 ◽  
Vol 115 (3) ◽  
pp. 499-505 ◽  
Author(s):  
Julian A. Guttman ◽  
Paul Janmey ◽  
A. Wayne Vogl
Keyword(s):  
Endoplasmic Reticulum ◽  
Phospholipase C ◽  
Sertoli Cells ◽  
Actin Filaments ◽  
Synthetic Peptide ◽  
Inositol Triphosphate ◽  
Binding Region ◽  
Phosphoinositide Pathway ◽  
Hydrolysis Of ◽  
Adhesion Complex

The gelsolin-phosphoinositide pathway may be part of the normal mechanism by which Sertoli cells regulate sperm release and turnover of the blood-testis barrier. The intercellular adhesion complexes (ectoplasmic specializations)involved with these two processes are tripartite structures consisting of the plasma membrane, a layer of actin filaments and a cistern of endoplasmic reticulum. Gelsolin is concentrated in these adhesion complexes. In addition,phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) and phosphoinositide-specific phospholipase C are found in the structures. Treatment of isolated spermatid/junction complexes with exogenous phosphoinositide-specific phospholipase C, or with a synthetic peptide consisting of the PtdIns(4,5)P2 binding region of gelsolin, results in the release of gelsolin and loss of actin from the adhesion complexes. We present a model for the disassembly of the actin layer of the adhesion complex that involves the hydrolysis of PtdIns(4,5)P2 resulting in the release of gelsolin within the plaque. Further, we speculate that the hydrolysis of PtdIns(4,5)P2 may result in a local Ca2+ surge via the action of inositol triphosphate on junctional endoplasmic reticulum. This Ca2+ surge would facilitate the actin severing function of gelsolin within the adhesion complex.

Selective Inhibition of Thromboxane Synthetase with Dazoxiben - Basis of Its Inhibitory Effect on Platelet Adhesion

1983 ◽  
Vol 49 (02) ◽  
pp. 096-101 ◽  
Author(s):  
V C Menys ◽  
J A Davies
Keyword(s):  
Arachidonic Acid ◽  
Platelet Adhesion ◽  
Fold Increase ◽  
Selective Inhibition ◽  
Inhibitory Effect ◽  
Selective Inhibitor ◽  
Coated Glass ◽  
Thromboxane Synthetase ◽  
Pre Treatment

SummaryPlatelet adhesion to rabbit aortic subendothelium or collagen-coated glass was quantitated in a rotating probe device by uptake of radio-labelled platelets. Under conditions in which aspirin had no effect, dazoxiben, a selective inhibitor of thromboxane synthetase, reduced platelet adhesion to aortic subendothelium by about 40% but did not affect adhesion to collagen-coated glass. Pre-treatment of aortic segments with 15-HPETE, a selective inhibitor of PGI2-synthetase, abolished the inhibitory effect of dazoxiben on adhesion. Concentrations of 6-oxo-PGFlα in the perfusate were raised in the presence of dazoxiben alone, and following addition of thrombin (10 units/ml) there was a 2-3 fold increase in concentration. Perfusion of damaged aorta with platelets labelled with (14C)-arachidonic acid in the presence of thrombin and dazoxiben resulted in the appearance of (14C)-labelled-6-oxo-PGFiα. Inhibition of thromboxane synthetase limits platelet adhesion probably by promoting vascular synthesis of PGI2 from endoperoxides liberated from adherent platelets, which subsequently promotes detachment of cells from the surface.

Follicle-stimulating hormone-dependent estrogen secretion by rat Sertoli cells in vitro: Modulation by calcium

1991 ◽  
Vol 125 (3) ◽  
pp. 280-285 ◽  
Author(s):  
J. Alan Talbot ◽  
Ann Lambert ◽  
Robert Mitchell ◽  
Marek Grabinski ◽  
David C. Anderson ◽  
...  
Keyword(s):  
Sertoli Cells ◽  
Culture Medium ◽  
Follicle Stimulating Hormone ◽  
Dibutyryl Camp ◽  
Immature Rat ◽  
Estradiol Secretion ◽  
Old Rats ◽  
Stimulating Hormone

Abstract We have investigated the role of Ca2+ in the control of FSH-induced estradiol secretion by Sertoli cells isolated from 8-10 days old rats. Exogenous Ca2+ (4-8 mmol/1) inhibited FSH-stimulated E2 secretion such that, with 8 mmol/l Ca2+ and FSH (8 IU/l) E2 secretion decreased from 2091±322 to 1480±84 pmol/l (p<0.002), whilst chelation of Ca2+ in the culture medium with EGTA (3 mmol/l) increased E2 secretion from 360±45 to 1242±133 pmol/l) in the absence of FSH. Further, EGTA (3 mmol/l) markedly potentiated FSH (8 IU/l), forskolin (1 μmol/l) and dibutyryl cAMP (1 mmol/l)-stimulated E2 secretion. Addition of the Ca2+ ionophores, ionomycin (2-5 μmol/l) and A23187 (2 μmol/l), inhibited FSH (8 IU/l)-stimulated E2 secretion by >80%. The effect of ionomycin was totally reversible, whereas that of A23187 was irreversible. Ionomycin (5 μmol/l) had no effect on EGTA-induced E2 secretion in the absence of FSH, but reduced EGTA-provoked E2 secretion by 59% in the presence of FSH (8 IU/l). Similarly, forskolin- and dibutyryl cAMP-provoked E2 production was inhibited 46-50% by ionomycin (5 μmol/l). We conclude that FSH-induced E2 secretion from immature rat Sertoli cells is modulated by intra- and extracellular Ca2+.

scholarly journals N-terminus oligomerization is conserved in intracellular calcium release channels

2014 ◽  
Vol 459 (2) ◽  
pp. 265-273 ◽  
Author(s):  
Spyros Zissimopoulos ◽  
Jason Marsh ◽  
Laurence Stannard ◽  
Monika Seidel ◽  
F. Anthony Lai
Keyword(s):  
Structure Function ◽  
Intracellular Calcium ◽  
Calcium Release ◽  
Function Parameter ◽  
Calcium Release Channels ◽  
Cellular Processes ◽  
N Terminus ◽  
Intracellular Calcium Release ◽  
Ca2 Channels

Intracellular Ca2+ channels are of paramount importance for numerous cellular processes. In the present paper we report on a novel N-terminus intersubunit interaction, an essential structure–function parameter, which is conserved in both families of intracellular Ca2+ channels.

Platelet-derived growth factor induces rapid and sustained tyrosine phosphorylation of phospholipase C-gamma in quiescent BALB/c 3T3 cells

1989 ◽  
Vol 9 (7) ◽  
pp. 2934-2943
Author(s):  
M I Wahl ◽  
N E Olashaw ◽  
S Nishibe ◽  
S G Rhee ◽  
W J Pledger ◽  
...  
Keyword(s):  
Growth Factor ◽  
Phospholipase C ◽  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Hormonal Regulation ◽  
Growth Factor Receptor ◽  
Fold Increase ◽  
Platelet Derived Growth Factor ◽  
3T3 Cells ◽  
Pdgf Stimulation

Platelet-derived growth factor (PDGF) stimulates the proliferation of quiescent fibroblasts through a series of events initiated by activation of tyrosine kinase activity of the PDGF receptor at the cell surface. Physiologically significant substrates for this or other growth factor receptor or oncogene tyrosine kinases have been difficult to identify. Phospholipase C (PLC), a key enzyme of the phosphoinositide pathway, is believed to be an important site for hormonal regulation of the hydrolysis of phosphatidylinositol 4,5-bisphosphate, which produces the intracellular second-messenger molecules inositol 1,4,5-trisphosphate and 1,2-diacylglycerol. Treatment of BALB/c 3T3 cells with PDGF led to a rapid (within 1 min) and significant (greater than 50-fold) increase in PLC activity, as detected in eluates of proteins from a phosphotyrosine immunoaffinity matrix. This PDGF-stimulated increase in phosphotyrosine-immunopurified PLC activity occurred for up to 12 h after addition of growth factor to quiescent cells. Interestingly, the PDGF stimulation occurred at 3 as well as 37 degrees C and in the absence or presence of extracellular Ca2+. Immunoprecipitation of cellular proteins with monoclonal antibodies specific for three distinct cytosolic PLC isozymes demonstrated the presence of a 145-kilodalton isozyme, PLC-gamma (formerly PLC-II), in BALB/c 3T3 cells. Furthermore, these immunoprecipitation studies showed that PLC-gamma is rapidly phosphorylated on tyrosine residues after PDGF stimulation. The results suggest that mitogenic signaling by PDGF is coincident with tyrosine phosphorylation of PLC-gamma.

scholarly journals Characteristic of the vasorlaxant action of the talatisamine alkaloid and its derivatives

2021 ◽  
Vol 4 (2) ◽  
pp. 01-05
Author(s):  
Mirzayeva Yu.T.
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Channel Blocker ◽  
Aortic Ring ◽  
Diterpenoid Alkaloids ◽  
Relaxant Effect ◽  
Ring Contraction ◽  
Voltage Dependent ◽  
Ca2 Channels ◽  
Isolated Rat

The aim of our research is to study the effect relaxant action of diterpenoid alkaloids talatisamine, 14-O-benzoylthalatisamine and 14-O-acetylthalatisamine was studied using isolated rat aortic rings. Alkaloids significantly and dose-dependently inhibited contraction of the aortic rings caused by high KCl content. At the same time, under these conditions, alkaloids significantly reduced Ca2+-induced contraction of the aortic rings. The relaxing effects of alkaloids are significantly suppressed by verapamil, a potent potentiometer-dependent Ca2+ channel blocker. The alkaloids also significantly reduced norepinephrine-induced aortic ring contraction in normal as well as Ca2+ free Krebs solutions. The data obtained indicate that talatisamine, 14-benzoylthalatisamine and 14-O-acetylthalatisamine exhibit a pronounced relaxant effect in almost the same way in the case of contraction induced by a high content of KCl and norepinephrine. The mechanism of the relaxant action of alkaloids is probably complex and may include suppression of Ca2+influx through voltage-dependent and receptor-driven Ca2+ channels, as well as inhibition of Ca2+transport in the sarcoplasmic reticulum.

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