scholarly journals Integration of Inositol Phosphate Signaling Pathways via Human ITPK1

2007 ◽  
Vol 282 (38) ◽  
pp. 28117-28125 ◽  
Author(s):  
Philip P. Chamberlain ◽  
Xun Qian ◽  
Amanda R. Stiles ◽  
Jaiesoon Cho ◽  
David H. Jones ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Chloride Channels ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Structural Features ◽  
Signaling Mechanism ◽  
Metabolic Role ◽  
Inositol 1,4,5 Trisphosphate ◽  
High Resolution Structure ◽  
Substrate Regulation

Inositol 1,3,4-trisphosphate 5/6-kinase (ITPK1) is a reversible, poly-specific inositol phosphate kinase that has been implicated as a modifier gene in cystic fibrosis. Upon activation of phospholipase C at the plasma membrane, inositol 1,4,5-trisphosphate enters the cytosol and is inter-converted by an array of kinases and phosphatases into other inositol phosphates with diverse and critical cellular activities. In mammals it has been established that inositol 1,3,4-trisphosphate, produced from inositol 1,4,5-trisphosphate, lies in a branch of the metabolic pathway that is separate from inositol 3,4,5,6-tetrakisphosphate, which inhibits plasma membrane chloride channels. We have determined the molecular mechanism for communication between these two pathways, showing that phosphate is transferred between inositol phosphates via ITPK1-bound nucleotide. Intersubstrate phosphate transfer explains how competing substrates are able to stimulate each others' catalysis by ITPK1. We further show that these features occur in the human protein, but not in plant or protozoan homologues. The high resolution structure of human ITPK1 identifies novel secondary structural features able to impart substrate selectivity and enhance nucleotide binding, thereby promoting intersubstrate phosphate transfer. Our work describes a novel mode of substrate regulation and provides insight into the enzyme evolution of a signaling mechanism from a metabolic role.

scholarly journals Relationships between the degree of cross-linking of surface immunoglobulin and the associated inositol 1,4,5-trisphosphate and Ca2+ signals in human B cells

1992 ◽  
Vol 284 (2) ◽  
pp. 447-455 ◽  
Author(s):  
F M McConnell ◽  
S B Shears ◽  
P J L Lane ◽  
M S Scheibel ◽  
E A Clark
Keyword(s):  
B Cells ◽  
Tyrosine Kinase ◽  
Phospholipase C ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Cross Linking ◽  
Immunoglobulin Receptor ◽  
Surface Immunoglobulin ◽  
Human B Cells ◽  
Inositol 1,4,5 Trisphosphate

Cross-linking of surface immunoglobulin (Ig) receptors on human B cells leads to the activation of a tyrosine kinase. The activated tyrosine kinase subsequently phosphorylates a number of substrates, including phospholipase C-gamma. This enzyme breaks down phosphoinositol bisphosphate to form two intracellular messengers, diacylglycerol and inositol 1,4,5-trisphosphate, leading to the activation of protein kinase C and the release of intracellular Ca2+ respectively. We have used h.p.l.c. and flow cytometry to measure accurately the inositol phosphate turnover and Ca2+ release in anti-Ig-stimulated human B cells. In particular, we have examined the effect of dose of the cross-linking antibody on the two responses. The identity of putative messenger inositol phosphates has been verified by structural analysis, and the amounts of both inositol phosphates and Ca2+ present have been quantified. In the Ramos Burkitt lymphoma, which is very sensitive to stimulus through its Ig receptors, both inositol phosphate production and Ca2+ release were found to be related to the dose of anti-Ig antibody applied. This suggests that phospholipase C-mediated signal transduction in human B cells converts the degree of cross-linking of the immunoglobulin receptor quantitatively into intracellular signals.

scholarly journals Breakdown of polyphosphoinositides and not phosphatidylinositol accounts for muscarinic agonist-stimulated inositol phospholipid metabolism in rat parotid glands

1983 ◽  
Vol 216 (3) ◽  
pp. 633-640 ◽  
Author(s):  
C P Downes ◽  
M M Wusteman
Keyword(s):  
Molecular Mechanisms ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Muscarinic Agonist ◽  
Parotid Glands ◽  
Muscarinic Agonists ◽  
Inositol 1 ◽  
Inositol 1,4,5 Trisphosphate ◽  
Rat Parotid ◽  
Phosphatidylinositol 4

The molecular mechanisms underlying the ability of muscarinic agonists to enhance the metabolism of inositol phospholipids were studied using rat parotid gland slices prelabelled with tracer quantities of [3H]inositol and then washed with 10 mM unlabelled inositol. Carbachol treatment caused rapid and marked increases in the levels of radioactive inositol 1-phosphate, inositol 1,4-bisphosphate, inositol 1,4,5-trisphosphate and an accumulation of label in the free inositol pool. There were much less marked changes in the levels of [3H]phosphatidylinositol, [3H]phosphatidylinositol 4-phosphate and [3H]phosphatidylinositol 4,5-bisphosphate. At 5 s after stimulation with carbachol there were large increases in [3H]inositol 1,4-bisphosphate and [3H]inositol 1,4,5-trisphosphate, but not in [3H]inositol 1-phosphate. After stimulation with carbachol for 10 min the levels of radioactive inositol 1,4-bisphosphate and inositol 1,4,5-trisphosphate greatly exceeded the starting level of radioactivity in phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate respectively. When carbachol treatment was followed by addition of sufficient atropine to block all the muscarinic receptors the radioactive inositol phosphates rapidly returned towards control levels. The carbachol-evoked changes in radioactive inositol phosphate and phospholipid levels were blocked in the presence of 2,4-dinitrophenol (an uncoupler of oxidative phosphorylation). The results suggest that muscarinic agonists stimulate a polyphosphoinositide-specific phospholipase C and that these lipids are continuously replenished from the labelled phosphatidylinositol pool. [3H]Inositol 1-phosphate in the stimulated glands probably arises via hydrolysis of inositol 1,4-bisphosphate and not directly from phosphatidylinositol.

Ca2+ stores in smooth muscle cells: Ca2+ buffering and coupling to AVP-evoked inositol phosphate synthesis

1994 ◽  
Vol 266 (1) ◽  
pp. C276-C283 ◽  
Author(s):  
D. M. Berman ◽  
T. Sugiyama ◽  
W. F. Goldman
Keyword(s):  
Smooth Muscle ◽  
Inverse Relationship ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Enzyme System ◽  
Similar Treatment ◽  
A7r5 Cells ◽  
Inositol 1,4,5 Trisphosphate ◽  
Communication Pathway

Cytosolic Ca2+ concentrations ([Ca2+]cyt) and [3H]inositol phosphates ([3H]InsP) were correlated while decreasing the Ca2+ content of sarcoplasmic reticulum (SR) stores in cultured A7r5 cells at rest and after activation with 8-arginine vasopressin (AVP). Decreasing Ca2+ influx by reducing extracellular Ca2+ or by treatment with verapamil had no effect on resting [Ca2+]cyt but significantly inhibited the AVP-evoked Ca2+ transients (delta Ca2+). Neither treatment affected basal [3H]InsP, but both treatments increased AVP-evoked synthesis of [3H]InsP. Likewise, basal [3H]InsP were unaffected by brief (10-30 s) exposures to thapsigargin (TG), while AVP-induced [3H]InsP synthesis was significantly augmented. Similar treatment with TG rapidly increased resting [Ca2+]cyt and decreased SR Ca2+ by 9-25% as manifested by decreased delta Ca2+. By contrast, ryanodine induced slow increases in [Ca2+]cyt that stabilized within 30 min; subsequent AVP-induced delta Ca2+ were attenuated by 50%. Ryanodine had no effect on either basal or stimulated [3H]InsP levels. Agents that elevate adenosine 3',5'-cyclic monophosphate (cAMP) such as caffeine, 8-bromo-cAMP, and forskolin inhibited AVP-evoked [3H]InsP formation. These observations provide further characterization of a communication pathway between the AVP-sensitive Ca2+ stores in the SR and the plasmalemmal enzyme system involved in the synthesis of inositol 1,4,5-trisphosphate. This pathway is manifested by an inverse relationship between the Ca2+ content of an AVP-sensitive, ryanodine-insensitive SR Ca2+ store and evoked [3H]InsP synthesis and may represent an important component in the tonic regulation of resting [Ca2+]cyt and vasoconstrictor- and hormone-evoked SR Ca2+ release.

Effects of adenosine on cAMP production and cytosolic Ca2+ in cultured rabbit medullary thick limb cells

1991 ◽  
Vol 260 (1) ◽  
pp. C143-C150 ◽  
Author(s):  
M. A. Burnatowska-Hledin ◽  
W. S. Spielman
Keyword(s):  
Adenosine Receptor ◽  
Cultured Cells ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Inhibitory Effect ◽  
Free Calcium ◽  
Thick Ascending Limb ◽  
Camp Production ◽  
Signaling Mechanism ◽  
Adenosine Receptor Agonists

The cellular signaling mechanism of adenosine action has been studied in highly purified populations of cultured cells from the rabbit medullary thick ascending limb of Henle's loop (MTAL). The effects of specific adenosine-receptor agonists 5'(N-ethylcarboxamido)adenosine (NECA; A2) and N6-cyclohexyladenosine (CHA; A1) on basal and hormone-stimulated adenosine 3',5'-cyclic monophosphate (cAMP) production, cytosolic free calcium concentration ([Ca2+]f), and formation of inositol phosphates were examined. Production of cAMP was stimulated by high doses of NECA and was inhibited by low doses of CHA. The inhibitory effect of CHA was observed in cells in which cAMP production was first stimulated with vasopressin, isoproterenol, prostaglandin E2 (10(-6) M), or calcitonin (100 ng/ml) and was abolished by pretreating the cells with pertussis toxin (PT) for 12-20 h. A highly selective adenosine A1 antagonist, 8-cyclopentyl-1,3-dipropylxanthine (CPX), also abolished the inhibitory effect of CHA. Both NECA and CHA induced a rapid (10 s) and transient increase in [Ca2+]f, and this was associated with an increased inositol trisphosphate (IP3) production. Single-cell [Ca2+]f measurements indicated that all MTAL cells responded to CHA. The removal of extracellular Ca2+ failed to inhibit these responses. Pretreatment with PT or administration of CPX abolished both the increase in [Ca2+]f and the formation of IP3 occurring in response to CHA and NECA. Our results suggest that both adenylate cyclase-coupled inhibitory (A1) and stimulatory (A2) adenosine receptors are present in pure populations of cultured MTAL cells. Moreover, activation of an adenosine receptor coupled to a PT substrate results in the increased production of inositol phosphate and elevation of [Ca2+]f.

scholarly journals Thyrotropin Stimulates the Generation of Inositol 1,4,5-Trisphosphate in Human Thyroid Cells

2006 ◽  
Vol 91 (3) ◽  
pp. 1099-1107 ◽  
Author(s):  
Jacqueline Van Sande ◽  
Didier Dequanter ◽  
Philippe Lothaire ◽  
Claude Massart ◽  
Jacques E. Dumont ◽  
...  
Keyword(s):  
Phospholipase C ◽  
Cell Line ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Human Cells ◽  
Human Thyroid ◽  
Fresh Tissue ◽  
Thyroid Cells ◽  
Thyroid Stimulating Antibodies ◽  
Inositol 1,4,5 Trisphosphate

Abstract Context: Dual activation by TSH of the phospholipase C and cAMP cascades has been reported in human thyroid cells. In contrast, Singh et al. reported convincing data in FRTL-5 thyrocytes arguing against such an effect in this model. Their data in FRTL-5 cells indicated no increase in inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] in response to TSH. Therefore, the authors questioned results previously obtained on human cells by cruder methodology. Objective: We investigated the formation of inositol phosphates by HPLC techniques in human thyroid slices to separate the inositol phosphate isomers. Results: Ins(1,4,5)P3, inositol 1,3,4-trisphosphate, and inositol 1,3,4,5-tetrakisphosphate were increased after TSH stimulation. The effect of TSH in human thyroid cells was reproduced by recombinant TSH and prevented by antibodies blocking the TSH receptor. Thyroid-stimulating antibodies at concentrations eliciting a cAMP response equivalent to TSH failed to stimulate inositol phosphate generation. Conclusions: TSH, but not thyroid-stimulating antibodies, activates both cAMP and the phospholipase C cascade in human thyroid as now demonstrated by an increase in Ins(1,4,5)P3 and its inositol phosphate metabolites. Therefore, this effect cannot be extrapolated to the FRTL-5 cell line. The apparent discrepancy may be due to a difference between species (human vs. rat) or to the loss of the fresh tissue properties in a cell line. The dual effect of TSH in human cells, through cAMP on secretion of thyroid hormones and through the diacylglycerol, Ins(1,4,5)P3 Ca2+ pathway on thyroid hormone synthesis, implies the possible separation of these effects in thyroid disease.

Evidence for direct non-genomic effects of triiodothyronine on bone rudiments in rats: Stimulation of the inositol phosphate second messenger system

1991 ◽  
Vol 125 (6) ◽  
pp. 603-608 ◽  
Author(s):  
Peter Lakatos ◽  
Paula H. Stern
Keyword(s):  
Plasma Membrane ◽  
Thyroid Hormones ◽  
Time Course ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Second Messenger ◽  
Cytosolic Calcium ◽  
Membrane Receptors ◽  
Free Calcium ◽  
Stimulation Of

Abstract. Thyroid hormones increase cytosolic free calcium by binding to plasma membrane receptors in several tissues. This calcium increase appears to initiate extranuclear effects in these tissues. Increases in cytosolic calcium are often a consequence of stimulation of inositol phosphate second messenger pathway. Several calcemic hormones act via this signal transduction route. Therefore we investigated the effects of the metabolically active T3 and the inactive analogues 3,5-diiodotyrosine and rT3 on the inositol phosphate pathway in fetal rat limb bone cultures prelabeled with [3H]myoinositol. Labelled inositol and inositol phosphates were separated by HPLC. There was a significant increase in the radioactivity in inositol bis- and trisphosphates after 1 min of exposure to 10−7 mol/l T3. Stimulation was also observed at 10−6 mol/l T3, but not at 10−5 mol/l. Time course studies demonstrated a rapid effect of T3 on inositol phosphates within 30 seconds that lasted through 5 min. After 20 min incubation with T3, no increase was observed in inositol mono- and bisphosphates, and a decrease was seen in inositol trisphosphate. Pretreatment with indomethacin prevented these effects of T3. 3,5-diiodothyrosine and rT3 did not affect inositol phosphate metabolism. These results suggest the existence of plasma membrane-associated receptors for T3 in bone, in addition to the nuclear receptors demonstrated previously. The role of these receptors in the effects of thyroid hormones on bone remains to be established.

scholarly journals Inositol 1,2-cyclic 4,5-trisphosphate is not a product of μscarinic receptor-stimulated phosphatidylinositol 4,5-bisphosphate hydrolysis in rat parotid glands

1987 ◽  
Vol 243 (1) ◽  
pp. 211-218 ◽  
Author(s):  
P T Hawkins ◽  
C P Berrie ◽  
A J Morris ◽  
C P Downes
Keyword(s):  
Parotid Gland ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Water Soluble ◽  
Parotid Glands ◽  
Inositol 1 ◽  
Inositol 1,4,5 Trisphosphate ◽  
Cyclic Phosphate ◽  
Rat Parotid ◽  
Cyclic Compounds

We have employed a neutral-pH extraction technique to look for inositol 1,2-cyclic phosphate derivatives in [3H]inositol-labelled parotid gland slices stimulated with carbachol. The incubations were terminated by adding cold chloroform/methanol (1:2, v/v), the samples were dried under vacuum and inositol phosphates were extracted from the dried residues by phenol/chloroform/water partitioning. Water-soluble inositol metabolites were separated by h.p.l.c. at pH 3.7. 32P-labelled inositol phosphate standards (inositol 1-phosphate, inositol 1,2-cyclic phosphate, inositol 1,4,5-trisphosphate and inositol 1,2-cyclic 4,5-trisphosphate) were quantitively recovered through both extraction and chromatography steps. Treatment of inositol cyclic phosphate standards with 5% (w/v) HClO4 for 10 min prior to chromatography resulted in formation of the expected non-cyclic compounds. [3H]Inositol 1-phosphate and [3H]inositol 1,4,5-trisphosphate were both present in parotid gland slices and both increased during stimulation with 1 mM-carbachol. There was no evidence for significant quantities of [3H]inositol 1,2-cyclic phosphate or [3H]inositol 1,2-cyclic 4,5-trisphosphate in control or carbachol-stimulated glands. Parotid gland homogenates rapidly converted inositol 1,4,5-trisphosphate to inositol bisphosphate and inositol tetrakisphosphate, but metabolism of the inositol cyclic trisphosphate was much slower. The results suggest that inositol 1,4,5-trisphosphate, but not inositol 1,2-cyclic 4,5-trisphosphate, is the water-soluble product of muscarinic receptor-stimulated phospholipase C in rat parotid glands.

Ins(1,4,5)P3 and arrhythmogenic responses during myocardial reperfusion: evidence for receptor specificity

1997 ◽  
Vol 273 (3) ◽  
pp. H1119-H1125 ◽  
Author(s):  
A. N. Jacobsen ◽  
X. J. Du ◽  
A. M. Dart ◽  
E. A. Woodcock
Keyword(s):  
Ventricular Fibrillation ◽  
G Proteins ◽  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Ischemia Reperfusion ◽  
Myocardial Reperfusion ◽  
Reperfusion Arrhythmias ◽  
Rat Hearts ◽  
Inositol 1,4,5 Trisphosphate ◽  
Phosphate Response

Reperfusion of ischemic rat hearts initiates the generation of inositol(1,4,5)trisphosphate [Ins(1,4,5)P3] and arrhythmias, provided that either norepinephrine or thrombin is present. In the current study, effects on endothelin-1 (ET-1) responses were investigated. Reperfusion of catecholamine-depleted, [3H]inositol-labeled hearts in the presence of ET-1 caused an increase in [3H]inositol phosphates (7,073 +/- 1,004 to 17,300 +/- 206 counts.min-1.g tissue-1, means +/- SE, n = 4, P < 0.01), which was quantitatively greater than the release observed under normoxic conditions, but there was no increase in [3H]Ins(1,4,5)P3. Gentamicin (150 microM) inhibited inositol phosphate responses in the presence of either norepinephrine or thrombin but did not inhibit the response to ET-1, providing additional evidence that the inositol phosphate response to ET-1 does not involve formation of Ins(1,4,5)P3, even under reperfusion conditions. In contrast to norepinephrine and thrombin, ET-1 did not initiate reperfusion arrhythmias (4.4% ventricular fibrillation compared with 0% ventricular fibrillation in catecholamine-depleted controls). The data provide strong evidence that the effect of ischemia-reperfusion on inositol phosphate responses is specific for particular receptor types and eliminates G proteins, phospholipase C enzymes, and substrate availability as the primary factors responsible for Ins(1,4,5)P3 generation under reperfusion conditions.

scholarly journals Increase in cytosolic Ca2+ induced by elevation of extracellular Ca2+ in skeletal myogenic cells

2003 ◽  
Vol 284 (4) ◽  
pp. C969-C976 ◽  
Author(s):  
Fabio Naro ◽  
Vania De Arcangelis ◽  
Dario Coletti ◽  
Mario Molinaro ◽  
Bianca Zani ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Line ◽  
Satellite Cell ◽  
Arginine Vasopressin ◽  
Inositol Phosphate ◽  
Myoblast Differentiation ◽  
Membrane Hyperpolarization ◽  
Myogenic Potential ◽  
Inositol 1,4,5 Trisphosphate ◽  
Intracellular Ca

Cytoplasmic Ca2+concentration ([Ca2+]i) variation is a key event in myoblast differentiation, but the mechanism by which it occurs is still debated. Here we show that increases of extracellular Ca2+ concentration ([Ca2+]o) produced membrane hyperpolarization and a concentration-dependent increase of [Ca2+]i due to Ca2+influx across the plasma membrane. Responses were not related to inositol phosphate turnover and Ca2+-sensing receptor. [Ca2+]o-induced [Ca2+]i increase was inhibited by Ca2+ channel inhibitors and appeared to be modulated by several kinase activities. [Ca2+]i increase was potentiated by depletion of intracellular Ca2+ stores and depressed by inactivation of the Na+/Ca2+exchanger. The response to arginine vasopressin (AVP), which induces inositol 1,4,5-trisphosphate-dependent [Ca2+]i increase in L6-C5 cells, was not modified by high [Ca2+]o. On the contrary, AVP potentiated the [Ca2+]i increase in the presence of elevated [Ca2+]o. Other clones of the L6 line as well as the rhabdomyosarcoma RD cell line and the satellite cell-derived C2-C12 line expressed similar responses to high [Ca2+]o, and the amplitude of the responses was correlated with the myogenic potential of the cells.

Regulation of plasma membrane-bound Ca(2+)-ATPase pump by inositol phosphates in rat brain

1992 ◽  
Vol 262 (3) ◽  
pp. F411-F416
Author(s):  
C. L. Fraser ◽  
P. Sarnacki
Keyword(s):  
Signal Transduction ◽  
Plasma Membrane ◽  
Rat Brain ◽  
Inositol Phosphates ◽  
Stimulatory Action ◽  
Inositol 1,4,5 Trisphosphate ◽  
Membrane Bound

We have previously shown that inositol 1,4,5-trisphosphate (1,4,5-IP3) may participate in signal transduction in brain by inhibiting plasma membrane-bound Na(+)-Ca2+ exchanger. This study was therefore designed to determine whether 1,4,5-IP3 and/or inositol 1,3,4,5-tetrakisphosphate (1,3,4,5-IP4) might also affect Ca2+ transport by the plasma membrane Ca(2+)-ATPase pump. Our data show that 1,4,5-IP3 significantly (P less than 0.005) stimulates Ca2+ transport, whereas 1,3,4,5-IP4 significantly (P less than 0.006) inhibits transport by the pump. However, in the presence of both 1,4,5-IP3 and 1,3,4,5-IP4, the stimulatory effect of 1,4,5-IP3 is dominant. Thus Ca2+ transport was significantly stimulated as though 1,4,5-IP3 alone was present. We also observed that 1,3,4-IP3, which had no effect on Ca2+ transport by itself, antagonizes the stimulatory action of 1,4,5-IP3 and potentiates the inhibition of Ca2+ transport by 1,3,4,5-IP4. Half-maximal activities were observed at 10(-8) M. Our data suggest that 1,3,4,5-IP4, 1,4,5-IP3, and 1,3,4-IP3 may participate in signal transduction in brain by regulating the plasma membrane-bound Ca(2+)-ATPase pump.

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