scholarly journals Stereospecific mobilization of intracellular Ca2+ by inositol 1,4,5-triphosphate. Comparison with inositol 1,4,5-trisphosphorothioate and inositol 1,3,4-trisphosphate

1988 ◽  
Vol 253 (3) ◽  
pp. 901-905 ◽  
Author(s):  
J Strupish ◽  
A M Cooke ◽  
B V L Potter ◽  
R Gigg ◽  
S R Nahorski
Keyword(s):  
Pituitary Tumour ◽  
Gh3 Cells ◽  
Maximal Response ◽  
The Novel ◽  
3T3 Cells ◽  
High Concentration ◽  
Rat Pituitary ◽  
Active Isomer ◽  
Swiss 3T3 ◽  
First Time

The stereo specificity of myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] to mobilize Ca2+ from an intracellular store has been examined in permeabilized rat pituitary-tumour GH3 and Swiss 3T3 cells. A comparison of D-Ins(1,4,5)P3 with the synthetic enantiomer L-Ins(1,4,5)P3 and the racemate DL-Ins(1,4,5)P3 clearly demonstrates the marked stereospecificity of the response. Whereas D-Ins(1,4,5)P3 released 30-50% of non-mitochondrially-bound Ca2+ with a EC50 (concentration producing 50% of maximal response) of 200 nM, the L isomer was both substantially less potent and efficacious. A high concentration of the L isomer (10 microM) did not significantly shift the dose-response curve for the D isomer in Swiss 3T3 cells, suggesting that the less active isomer is probably a very weak agonist. Other studies revealed, in contrast with previous work, that the other naturally occurring isomer, D-Ins(1,3,4)P3, was essentially inactive in releasing Ca+, whereas a novel 5-phosphatase-resistant analogue, DL-myo-inositol 1,4,5-trisphosphorothioate, was a relatively potent full agonist in GH3 cells. These data reveal, for the first time, the stereoselectivity of the intracellular receptor associated with Ca2+ release. They also provide evidence for the activity of the novel phosphorothioate analogue of Ins(1,4,5)P3, but suggest that D-Ins(1,3,4)P3 is not involved in cellular Ca2+ mobilization.

On the involvement of cyclic AMP and extracellular Ca2+ in the regulation of hormone release from rat pituitary tumour (GH3) cells in culture

1987 ◽  
Vol 7 (2) ◽  
pp. 93-105 ◽  
Author(s):  
Kjersti Sletholt ◽  
Egil Haug ◽  
Kaare M. Gautvik
Keyword(s):  
Cyclic Amp ◽  
Pituitary Tumour ◽  
Gh3 Cells ◽  
Ionophore A23187 ◽  
Channel Blockers ◽  
Hormone Release ◽  
Calmodulin Antagonist ◽  
Rat Pituitary ◽  
Combined Action ◽  
Dose Dependent

Thyroliberin (TRH), dibutyryl cyclic AMP (db-cAMP), and 3-isobutyl-l-methylxanthine (MIX) had a stimulatory effect on prolactin (PRL) and growth hormone (GH) release from GH 3 cells. Half-maximal and maximal effects were observed for TRH at 2.5 nM and 10 nM; for db-cAMP at 0.6 mM and 5 mM, respectively. MIX (0.1 mM-1 mM) induced a dose-dependent accumulation of cellular cyclic AMP, while the hormone release was already maximally stimulated at 0.1 mM MIX. The maximal effects on hormone release of TRH and db-cAMP, but not of TRH and MIX, were additive. The Ca2+ channel blockers Co2+ (5 mM) and verapamil (100 μM) and the Ca2+ chelator EGTA (4 mM) abolished the stimulatory effect of TRH (1 μM) on hormone release. Co2+ and verapamil, but not EGTA, inhibited the stimulatory effect of db-cAMP (5 mM) on hormone release. The inhibitory effects of Co2+ and verapamil on GH release were counteracted by the combination of TRH and db-cAMP. For PRL release Co2+, but not verapamil, was able to inhibit the combined action of TRH and db-cAMP. Co2+, verapamil, and EGTA eliminated the stimulatory effect of MIX (1 mM) on PRL release while only Co2+ and EGTA affected the GH release. Hormone release in the presence of MIX plus verapamil or EGTA, but not Co2+, was increased by TRH. The calmodulin antagonist trifluoperazine (TFP) at 30 μM inhibited basal hormone release and hormone release stimulated by TRH (1 μM), db-cAMP (5 mM), and MIX (1 mM). The Ca2+ ionophore A23187 (5 μM) had a stimulatory effect on basal hormone release which was abolished by 30 μM TFP.

scholarly journals Metabolism of inositol bis-, tris-, tetrakis- and pentakis-phosphates in GH3 cells

1988 ◽  
Vol 250 (2) ◽  
pp. 493-500 ◽  
Author(s):  
N M Dean ◽  
J D Moyer
Keyword(s):  
Inositol Phosphates ◽  
Pituitary Tumour ◽  
Tumour Cells ◽  
Gh3 Cells ◽  
Rat Pituitary ◽  
Potential Sources ◽  
A Minor ◽  
Gh3 Cell

Previous studies demonstrated a multiplicity of isomers of inositol phosphates in GH3 rat pituitary tumour cells. In order to determine their origin, we have investigated the metabolism of radiolabelled inositol phosphates (IPn) in GH3 cell homogenates by using h.p.l.c. I(1,4,5)P3 is either phosphorylated to I(1,3,4,5)P4 (in the presence of ATP) or dephosphorylated to I(1,4)P2 (in the absence of ATP). I(1,4)P2 is dephosphorylated to I(4)P (greater than 95%). I(1,3,4,5)P4 hydrolysis yields two products. By using dual-labelled [32P, 3H]I(1,3,4,5)P4 with 32P in either the 3 or the 4/5 position, we have identified the probable configuration of these isomers. The predominant (greater than 97%) IP3 formed is I(1,3,4)P3, with a minor I(1,4,5)P3 peak. Subsequent I(1,3,4)P3 hydrolysis yields two IP2 isomers [the major (approximately equal to 85%) is I(3,4)P2; the minor (approximately equal to 15%) is I(1,3)P2] and two IP isomers (the major (approximately equal to 90%) is I(3)P [L-I(1)P], the minor I(4)P). IP5 is very slowly dephosphorylated to and IP4 of undetermined isomeric configuration. We have also examined GH3 cell lipids for the presence of phosphoinositides either more highly phosphorylated than PIP2 (as potential sources of the IP4/IP5 and IP6 in these cells) or phosphorylated in positions other than 1, 4 and 5, and have been unable to find evidence of either. These data suggest two main routes of metabolism for I(1,4,5)P3 in GH3 cells: either (1) phosphorylation to I(1,3,4,5)P4, and the subsequent consecutive dephosphorylation to I(1,3,4)P3, I(3,4)P2 and finally L-I(1)P [D-I(3)P]; or (2) dephosphorylation to I(1,4)P2 and, subsequently, I(4)P.

scholarly journals Endothelin stimulates DNA synthesis in Swiss 3T3 cells. Synergy with polypeptide growth factors

1989 ◽  
Vol 263 (3) ◽  
pp. 977-980 ◽  
Author(s):  
K D Brown ◽  
C J Littlewood
Keyword(s):  
Growth Factors ◽  
Dna Synthesis ◽  
Inositol Phosphates ◽  
Fold Increase ◽  
Maximal Response ◽  
Maximal Effect ◽  
Serum Free Medium ◽  
3T3 Cells ◽  
Polypeptide Growth Factors ◽  
Swiss 3T3

The vasoactive peptide endothelin is shown to be a potent mitogen for Swiss 3T3 cells. Although endothelin has little effect on DNA synthesis when added alone to cells in serum-free medium, the peptide synergizes very strongly with several other growth factors. A half-maximal response to endothelin is observed at approx. 0.3 nM, with a maximal effect at 3 nM. Over the same concentration range, endothelin stimulates a 2-fold increase in the accumulation of cellular inositol phosphates. Endothelin may prove to be a useful additional agonist for studying the signalling pathways involved in the control of 3T3-cell proliferation.

scholarly journals Thyrotropin-releasing hormone receptor occupancy determines the fraction of the responsive pool of inositol lipids hydrolysed in rat pituitary tumour cells

1990 ◽  
Vol 271 (2) ◽  
pp. 331-336 ◽  
Author(s):  
A B Cubitt ◽  
E Geras-Raaka ◽  
M C Gershengorn
Keyword(s):  
Receptor Occupancy ◽  
Pituitary Tumour ◽  
Thyrotropin Releasing Hormone ◽  
Gh3 Cells ◽  
Releasing Hormone ◽  
Receptor Complexes ◽  
Trh Stimulation ◽  
Rat Pituitary ◽  
Hydrolysis Of ◽  
Trh Receptor

We report that there are distinct thyrotropin-releasing hormone (TRH)-responsive and -unresponsive pools of inositol (Ins) lipids in rat pituitary tumour (GH3) cells, and present evidence that the size of the responsive pool is determined by the number of activated TRH-receptor complexes. By use of an experimental protocol in which cycling of [3H]Ins is inhibited and resynthesis occurs with unlabelled Ins only, we were able to measure specifically the effects of TRH on the hydrolysis of the Ins lipids present before stimulation. A maximally effective dose of TRH (1 microM) caused a time-dependent decrease in 3H-labelled Ins lipids that attained a steady-state value of 42 +/- 1% of the initial level between 1.5 and 2 h. After 2 h, even though there was no further decrease in 3H-labelled Ins lipids, and no increase in [3H]Ins or [3H]Ins phosphates, turnover of Ins lipids, as assessed as incorporation of [32P]Pi into PtdIns, continued at a rate similar to that in cells incubated without LiCl or unlabelled Ins. These data indicate that Ins lipid turnover was not desensitized during prolonged TRH stimulation. Depletion of lipid 3H radioactivity by TRH occurred at higher TRH doses on addition of the competitive antagonist chlordiazepoxide. Addition of 1 microM-TRH after 3 h of stimulation by a sub-maximal (0.3 nM) TRH dose caused a further decrease in 3H radioactivity to the minimum level (40% of initial value). We propose that the TRH-responsive pool of Ins lipids in GH3 cells is composed of the complement of Ins lipids that are within functional proximity of activated TRH-receptor complexes.

scholarly journals Involvement of bone morphogenetic protein-4 in GH regulation by octreotide and bromocriptine in rat pituitary GH3 cells

2008 ◽  
Vol 197 (1) ◽  
pp. 159-169 ◽  
Author(s):  
Tomoko Miyoshi ◽  
Fumio Otsuka ◽  
Hiroyuki Otani ◽  
Kenichi Inagaki ◽  
Junko Goto ◽  
...  
Keyword(s):  
Bone Morphogenetic Protein ◽  
Gh3 Cells ◽  
Individual Treatment ◽  
Camp Production ◽  
High Concentration ◽  
Gh Secretion ◽  
Camp Synthesis ◽  
Morphogenetic Protein ◽  
Rat Pituitary

Here we investigated roles of the pituitary bone morphogenetic protein (BMP) system in modulating GH production regulated by a somatostatin analog, octreotide (OCT) and a dopamine agonist, bromocriptine (BRC) in rat pituitary somatolactotrope tumor GH3 cells. The GH3 cells were found to express BMP ligands, including BMP-4 and BMP-6; BMP type-1 and type-2 receptors (except the type-1 receptor, activin receptor-like kinase (ALK)-6); and Smad signaling molecules. Forskolin stimulated GH production in accordance with cAMP synthesis. BRC, but not OCT, suppressed forskolin-induced cAMP synthesis by GH3 cells. Individual treatment with OCT and BRC reduced forskolin-induced GH secretion. A low concentration (0.1 μM) of OCT in combination with BRC (1–100 μM) exhibited additive effects on reducing GH and cAMP production induced by forskolin. However, a high concentration (10 μM) of OCT in combination with BRC failed to suppress GH and cAMP production. BMP-4 specifically enhanced GH secretion and cAMP production induced by forskolin in GH3 cells. BRC, but not OCT, inhibited BMP-4-induced activation of Smad1,5,8 phosphorylation and Id-1 transcription and decreased ALK-3 expression. Of note, in the presence of a high concentration of OCT, the BRC effects suppressing BMP-4-Smad1,5,8 signaling were significantly impaired. In the presence of BMP-4, a high concentration of OCT also attenuated the BRC effects suppressing forskolin-induced GH and cAMP production. Collectively, a high concentration of OCT interferes with BRC effects by reducing cAMP production and suppressing BMP-4 signaling in GH3 cells. These findings may explain the mechanism of resistance of GH reduction to a combination therapy with OCT and BRC for GH-producing pituitary adenomas.

Buried Narratives: Exhuming the Mother's Story in Oliver Twist

2018 ◽  
Vol 8 (3) ◽  
pp. 247-266
Author(s):  
Michelle L. Wilson
Keyword(s):  
Social Change ◽  
Maternal Inheritance ◽  
The Novel ◽  
Poor Law ◽  
The Family ◽  
The Law ◽  
First Time ◽  
Critical Consideration

Initially, Oliver Twist (1839) might seem representative of the archetypal male social plot, following an orphan and finding him a place by discovering the father and settling the boy within his inheritance. But Agnes Fleming haunts this narrative, undoing its neat, linear transmission. This reconsideration of maternal inheritance and plot in the novel occurs against the backdrop of legal and social change. I extend the critical consideration of the novel's relationship to the New Poor Law by thinking about its reflection on the bastardy clauses. And here, of course, is where the mother enters. Under the bastardy clauses, the responsibility for economic maintenance of bastard children was, for the first time, legally assigned to the mother, relieving the father of any and all obligation. Oliver Twist manages to critique the bastardy clauses for their release of the father, while simultaneously embracing the placement of the mother at the head of the family line. Both Oliver and the novel thus suggest that it is the mother's story that matters, her name through which we find our own. And by containing both plots – that of the father and the mother – Oliver Twist reveals the violence implicit in traditional modes of inheritance in the novel and under the law.

THE PRESENCE OF BIOSYNTHETIC PRECURSORS AND HETEROGENEOUS MESSENGER RNAs FOR PROLACTIN IN CULTURED RAT PITUITARY TUMOUR CELLS

1983 ◽  
Vol 104 (2_Supplb) ◽  
pp. S66-S69
Author(s):  
P. Aleström ◽  
E.J. Paulssen ◽  
V. Gautvik ◽  
M. Kriz ◽  
E. Haug ◽  
...  
Keyword(s):  
Pituitary Tumour ◽  
Tumour Cells ◽  
Messenger Rnas ◽  
Rat Pituitary

Application of Novel Low Current OBIRCH Amplifier and Nanoprobing to Identify Subtle Leakages in Advanced Node Technologies

2018 ◽  
Author(s):  
Satish Kodali ◽  
Liangshan Chen ◽  
Yuting Wei ◽  
Tanya Schaeffer ◽  
Chong Khiam Oh
Keyword(s):  
Signal To Noise Ratio ◽  
Semiconductor Industry ◽  
Fault Isolation ◽  
Ring Oscillator ◽  
High Signal ◽  
The Novel ◽  
Resistance Change ◽  
Three Samples ◽  
Relative Threshold ◽  
First Time

Abstract Optical beam induced resistance change (OBIRCH) is a very well-adapted technique for static fault isolation in the semiconductor industry. Novel low current OBIRCH amplifier is used to facilitate safe test condition requirements for advanced nodes. This paper shows the differences between the earlier and novel generation OBIRCH amplifiers. Ring oscillator high standby leakage samples are analyzed using the novel generation amplifier. High signal to noise ratio at applied low bias and current levels on device under test are shown on various samples. Further, a metric to demonstrate the SNR to device performance is also discussed. OBIRCH analysis is performed on all the three samples for nanoprobing of, and physical characterization on, the leakage. The resulting spots were calibrated and classified. It is noted that the calibration metric can be successfully used for the first time to estimate the relative threshold voltage of individual transistors in advanced process nodes.

Sign in / Sign up

Export Citation Format

Share Document