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The actin bundling activity of ITPKA mainly accounts for its migration-promoting effect in lung cancer cells. Biosci Rep 2023; 43:232487. [PMID: 36688944 PMCID: PMC9912108 DOI: 10.1042/bsr20222150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/29/2022] [Accepted: 01/09/2023] [Indexed: 01/24/2023] Open
Abstract
Expression of Ins(1,4,5)P3-kinase-A (ITPKA), the neuronal isoform of Ins(1,4,5)P3-kinases, is up-regulated in many tumor types. In particular, in lung cancer cells this up-regulation is associated with bad prognosis and it has been shown that a high level of ITPKA increases migration and invasion of lung cancer cell lines. However, since ITPKA exhibits actin bundling and Ins(1,4,5)P3-kinase activity, it was not clear which of these activities account for ITPKA-promoted migration and invasion of cancer cells. To address this issue, we inhibited endogenous actin bundling activity of ITPKA in lung cancer H1299 cells by overexpressing the dominant negative mutant ITPKAL34P. Analysis of actin dynamics in filopodia as well as wound-healing migration revealed that ITPKAL34P inhibited both processes. Moreover, the formation of invasive protrusions into collagen I was strongly blocked in cells overexpressing ITPKAL34P. Furthermore, we found that ATP stimulation slightly but significantly (by 13%) increased migration of cells overexpressing ITPKA while under basal conditions up-regulation of ITPKA had no effect. In accordance with these results, overexpression of a catalytic inactive ITPKA mutant did not affect migration, and the Ins(1,4,5)P3-kinase-inhibitor GNF362 reversed the stimulating effect of ITPKA overexpression on migration. In summary, we demonstrate that under basal conditions the actin bundling activity controls ITPKA-facilitated migration and invasion and in presence of ATP the Ins(1,4,5)P3-kinase activity slightly enhances this effect.
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Elich M, Sauer K. Regulation of Hematopoietic Cell Development and Function Through Phosphoinositides. Front Immunol 2018; 9:931. [PMID: 29780388 PMCID: PMC5945867 DOI: 10.3389/fimmu.2018.00931] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 04/16/2018] [Indexed: 01/01/2023] Open
Abstract
One of the most paramount receptor-induced signal transduction mechanisms in hematopoietic cells is production of the lipid second messenger phosphatidylinositol(3,4,5)trisphosphate (PIP3) by class I phosphoinositide 3 kinases (PI3K). Defective PIP3 signaling impairs almost every aspect of hematopoiesis, including T cell development and function. Limiting PIP3 signaling is particularly important, because excessive PIP3 function in lymphocytes can transform them and cause blood cancers. Here, we review the key functions of PIP3 and related phosphoinositides in hematopoietic cells, with a special focus on those mechanisms dampening PIP3 production, turnover, or function. Recent studies have shown that beyond “canonical” turnover by the PIP3 phosphatases and tumor suppressors phosphatase and tensin homolog (PTEN) and SH2 domain-containing inositol-5-phosphatase-1 (SHIP-1/2), PIP3 function in hematopoietic cells can also be dampened through antagonism with the soluble PIP3 analogs inositol(1,3,4,5)tetrakisphosphate (IP4) and inositol-heptakisphosphate (IP7). Other evidence suggests that IP4 can promote PIP3 function in thymocytes. Moreover, IP4 or the kinases producing it limit store-operated Ca2+ entry through Orai channels in B cells, T cells, and neutrophils to control cell survival and function. We discuss current models for how soluble inositol phosphates can have such diverse functions and can govern as distinct processes as hematopoietic stem cell homeostasis, neutrophil macrophage and NK cell function, and development and function of B cells and T cells. Finally, we will review the pathological consequences of dysregulated IP4 activity in immune cells and highlight contributions of impaired inositol phosphate functions in disorders such as Kawasaki disease, common variable immunodeficiency, or blood cancer.
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Affiliation(s)
- Mila Elich
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA, United States
| | - Karsten Sauer
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, United States.,Oncology R&D, Pfizer Worldwide R&D, San Diego, CA, United States
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ITPKA expression is a novel prognostic factor in hepatocellular carcinoma. Diagn Pathol 2015; 10:136. [PMID: 26249031 PMCID: PMC4528344 DOI: 10.1186/s13000-015-0374-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Accepted: 07/29/2015] [Indexed: 12/15/2022] Open
Abstract
Background Inositol-1,4,5-trisphosphate-3-kinase-A (ITPKA) has recently been found to be implicated in the tumor progression of various cancers. However, the expression and the prognostic value of ITPKA in hepatocellular carcinoma (HCC) remains unexplored. The aim of this study is to investigate the clinical significance of ITPKA expression in HCC. Methods We determined the expression level of ITPKA in 135 cases of HCC tissues and the matched adjacent nontumorous tissues by quantitative real-time RT-PCR. The correlation between ITPKA expression and prognosis of HCC patients was further evaluated by univariate and multivariate analysis. Multivariate analysis of the prognostic factors was performed with Cox proportional hazards model. Results Up-regulation of ITPKA occurred in 48.9 % of primary HCCs compared with their nontumor counterparts (P < 0.001). In addition, high expression of ITPKA was significantly associated with vascular invasion (P = 0.001) and TNM stage (P = 0.005). Kaplan–Meier analysis showed that the 5-year overall survival (OS) and relapse-free survival (RFS) rate in the group with high expression of ITPKA is poorer than that in low expression group (32.2 and 26.8 % versus 59.2 and 57.7 %). Univariate and multivariate analyses revealed that ITPKA was an independent prognostic factor for OS and RFS. Moreover, Stratified analysis revealed that its prognostic significance still existed within the subgroup of patients with early clinical stage (TNM stage I) or normal serum AFP level (≤25 μg/L). Conclusion Our data indicated that ITPKA expression was significantly up-regulated in HCC and could serve as a potential novel prognostic biomarker for HCC patients after surgery.
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Molinari G. Is hydrogen ion (H(+)) the real second messenger in calcium signalling? Cell Signal 2015; 27:1392-7. [PMID: 25843778 DOI: 10.1016/j.cellsig.2015.03.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 03/10/2015] [Accepted: 03/23/2015] [Indexed: 11/28/2022]
Abstract
Most second messengers have the acknowledged ability to mobilize the segregated Ca(2+) from intracellular stores, although the mechanisms of mobilization are unclear. To study this problem, the fact that inositol 1,4,5-trisphosphate, and six other known endogenous Ca(2+) mobilizers are acids, or acid-generating compounds, is highlighted. In physiological conditions, a newly generated acid releases H(+). The transient rise of H(+) in the cytosol may induce the lowering of pH, mobilization of bound Ca(2+), protein conformational rearrangement, store depletion, and Ca(2+) influx. Accordingly, a new description of the basic mechanism for signal transduction in non-excitable cells and the related consequences is put forward.
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Affiliation(s)
- Giuliano Molinari
- Biochemical Specialist at Molinari Giuliano, Via Agrigento 56, 37138 Verona Italy.
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Abstract
Second messenger molecules relay, amplify, and diversify cell surface receptor signals. Two important examples are phosphorylated D-myo-inositol derivatives, such as phosphoinositide lipids within cellular membranes, and soluble inositol phosphates. Here, we review how phosphoinositide metabolism generates multiple second messengers with important roles in T-cell development and function. They include soluble inositol(1,4,5)trisphosphate, long known for its Ca(2+)-mobilizing function, and phosphatidylinositol(3,4,5)trisphosphate, whose generation by phosphoinositide 3-kinase and turnover by the phosphatases PTEN and SHIP control a key "hub" of TCR signaling. More recent studies unveiled important second messenger functions for diacylglycerol, phosphatidic acid, and soluble inositol(1,3,4,5)tetrakisphosphate (IP(4)) in immune cells. Inositol(1,3,4,5)tetrakisphosphate acts as a soluble phosphatidylinositol(3,4,5)trisphosphate analog to control protein membrane recruitment. We propose that phosphoinositide lipids and soluble inositol phosphates (IPs) can act as complementary partners whose interplay could have broadly important roles in cellular signaling.
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Affiliation(s)
- Yina H Huang
- Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Regulation of B cell survival, development and function by inositol 1,4,5-trisphosphate 3-kinase B (Itpkb). ACTA ACUST UNITED AC 2010; 51:66-73. [PMID: 21035494 DOI: 10.1016/j.advenzreg.2010.08.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 08/31/2010] [Indexed: 10/18/2022]
Abstract
In mammals, Ins(1,4,5)P3, the well known calcium mobilization messenger, is phosphorylated in the cytosol at the 3-position of the inositol ring to yield Ins(1,3,4,5)P4 by Ins(1,4,5)P3 3-kinases A, B and C isoforms as well as by inositol polyphosphate multikinase (Ipmk). Studies in gene-deficient mice have revealed that these enzymes and Ins(1,3,4,5)P4, their reaction product, play essential role in multiple physiological processes, ranging from synaptic plasticity, hematopoietic cell survival, development and function, to mRNA export, transcriptional regulation and chromatin remodelling. Rather than to provide an unique and “universal” mechanism of Ins(1,3,4,5)P4 action, these studies in genetically-modified mice point for a role of this inositide in the control of calcium mobilization, of the subcellular localisation of PH domain-containing target proteins, and of higher inositol phosphate production. Mice deficient for the B isoform of inositol 1,4,5-trisphosphate 3-kinase (Itpkb) develop profound alterations in T and B cells as well as in neutrophils and mast cells. Our recent studies indicate that the 3-kinase Itpkb and Ins(1,3,4,5)P4 are important for the survival of naïve mature B cells and the control of proapoptotic Bim protein expression, rather than for the control of B cell transition from one developmental stage to another. They also suggest that Itpkb is an important component in the control of B cell anergy.
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Kitamura M, Nishimoto H, Aoki K, Tsukamoto M, Aoki S. Molecular recognition of inositol 1,4,5-trisphosphate and model compounds in aqueous solution by ditopic Zn(2+) complexes containing chiral linkers. Inorg Chem 2010; 49:5316-27. [PMID: 20420391 DOI: 10.1021/ic1004038] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report on molecular recognition of inositol 1,4,5-trisphosphate (Ins(1,4,5)P(3)), an important intracellular second messenger, and some related model compounds, cyclohexanediol bisphosphate derivatives (CDP(2)), by ditopic Zn(2+) complexes containing chiral linkers ((S,S)- and (R,R)-11) in aqueous solution at physiological pH. A crystal structure analysis of (S,S)-11 indicated that the distance between two Zn(2+) ions (6.8 A) is suitable for accommodating two phosphate groups at the 4- and 5-positions of Ins(1,4,5)P(3) and two phosphate groups of trans-1,2-CDP(2). (1)H NMR, (31)P NMR, potentiometric pH, and isothermal calorimetric titration data indicate that (S,S)-11 forms 1:1 complexes with (S,S)- and (R,R)-1,2-CDP(2) at pH 7.4 and 25 degrees C. The apparent 1:1 complexation constants (log K(app)) for (S,S)-11-(S,S)-1,2-CDP(2) and (S,S)-11-(R,R)-1,2-CDP(2) (K(app) = [(S,S)-11-1,2-CDP(2) complex]/[(S,S)-11][1,2-CDP(2)] (M(-1))) were determined to be 7.6 +/- 0.1 and 7.3 +/- 0.1, respectively, demonstrating that both enantiomers of 11 bind to chiral trans-1,2-CDP(2) to almost the same extent. The log K(app) value of 6.3 was obtained for a 1:1 complex of (S,S)-11 with cis-1,3-CDP(2), while a small amount of 2:1 (S,S)-11-cis-1,3-CDP(2) was detected, as evidenced by electrospray ionization mass spectrometry (ESI-MS). In contrast, 11 formed several complexes with trans-1,4-CDP(2). On the basis of isothermal titration calorimetry data for (S,S)- and (R,R)-11 with Ins(1,4,5)P(3), it was concluded that 11 forms a 2:1 complex with Ins(1,4,5)P(3), in which the first molecule of 11 binds to the 4- and 5-phosphates of Ins(1,4,5)P(3) and the second molecule of 11 binds to the 1- and 5-phosphates.
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Affiliation(s)
- Masanori Kitamura
- Faculty of Pharmaceutical Sciences, Tokyo University of Science,2641 Yamazaki, Noda 278-8510, Japan
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Schell MJ. Inositol trisphosphate 3-kinases: focus on immune and neuronal signaling. Cell Mol Life Sci 2010; 67:1755-78. [PMID: 20066467 PMCID: PMC11115942 DOI: 10.1007/s00018-009-0238-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 12/14/2009] [Accepted: 12/18/2009] [Indexed: 11/28/2022]
Abstract
The localized control of second messenger levels sculpts dynamic and persistent changes in cell physiology and structure. Inositol trisphosphate [Ins(1,4,5)P(3)] 3-kinases (ITPKs) phosphorylate the intracellular second messenger Ins(1,4,5)P(3). These enzymes terminate the signal to release Ca(2+) from the endoplasmic reticulum and produce the messenger inositol tetrakisphosphate [Ins(1,3,4,5)P(4)]. Independent of their enzymatic activity, ITPKs regulate the microstructure of the actin cytoskeleton. The immune phenotypes of ITPK knockout mice raise new questions about how ITPKs control inositol phosphate lifetimes within spatial and temporal domains during lymphocyte maturation. The intense concentration of ITPK on actin inside the dendritic spines of pyramidal neurons suggests a role in signal integration and structural plasticity in the dendrite, and mice lacking neuronal ITPK exhibit memory deficits. Thus, the molecular and anatomical features of ITPKs allow them to regulate the spatiotemporal properties of intracellular signals, leading to the formation of persistent molecular memories.
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Affiliation(s)
- Michael J Schell
- Department of Pharmacology, Uniformed Services University, 4301 Jones Bridge Rd, Bethesda, MD 20814, USA.
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Sauer K, Cooke MP. Regulation of immune cell development through soluble inositol-1,3,4,5-tetrakisphosphate. Nat Rev Immunol 2010; 10:257-71. [PMID: 20336153 PMCID: PMC2922113 DOI: 10.1038/nri2745] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The membrane lipid phosphatidylinositol-3,4,5-trisphosphate (PtdInsP(3)) regulates membrane receptor signalling in many cells, including immunoreceptor signalling. Here, we review recent data that have indicated essential roles for the soluble PtdInsP(3) analogue inositol-1,3,4,5-tetrakisphosphate (InsP(4)) in T cell, B cell and neutrophil development and function. Decreased InsP(4) production in leukocytes causes immunodeficiency in mice and might contribute to inflammatory vasculitis in Kawasaki disease in humans. InsP(4)-producing kinases could therefore provide attractive drug targets for inflammatory and infectious diseases.
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Affiliation(s)
- Karsten Sauer
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California 92037, USA.
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Sauer K, Huang YH, Lin H, Sandberg M, Mayr GW. Phosphoinositide and inositol phosphate analysis in lymphocyte activation. CURRENT PROTOCOLS IN IMMUNOLOGY 2009; Chapter 11:11.1.1-11.1.46. [PMID: 19918943 PMCID: PMC4500525 DOI: 10.1002/0471142735.im1101s87] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Lymphocyte antigen receptor engagement profoundly changes the cellular content of phosphoinositide lipids and soluble inositol phosphates. Among these, the phosphoinositides phosphatidylinositol 4,5-bisphosphate (PIP2) and phosphatidylinositol 3,4,5-trisphosphate (PIP3) play key signaling roles by acting as pleckstrin homology (PH) domain ligands that recruit signaling proteins to the plasma membrane. Moreover, PIP2 acts as a precursor for the second messenger molecules diacylglycerol and soluble inositol 1,4,5-trisphosphate (IP3), essential mediators of PKC, Ras/Erk, and Ca2+ signaling in lymphocytes. IP3 phosphorylation by IP3 3-kinases generates inositol 1,3,4,5-tetrakisphosphate (IP4), an essential soluble regulator of PH domain binding to PIP3 in developing T cells. Besides PIP2, PIP3, IP3, and IP4, lymphocytes produce multiple other phosphoinositides and soluble inositol phosphates that could have important physiological functions. To aid their analysis, detailed protocols that allow one to simultaneously measure the levels of multiple different phosphoinositide or inositol phosphate isomers in lymphocytes are provided here. They are based on thin layer, conventional and high-performance liquid chromatographic separation methods followed by radiolabeling or non-radioactive metal-dye detection. Finally, less broadly applicable non-chromatographic methods for detection of specific phosphoinositide or inositol phosphate isomers are discussed. Support protocols describe how to obtain pure unstimulated CD4+CD8+ thymocyte populations for analyses of inositol phosphate turnover during positive and negative selection, key steps in T cell development.
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Affiliation(s)
- Karsten Sauer
- The Scripps Research Institute, La Jolla, California
| | | | - Hongying Lin
- University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Mark Sandberg
- Genomics Institute of the Novartis Research Foundation (GNF), San Diego, California
| | - Georg W Mayr
- University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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11
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Oh DJ, Ahn KH. Fluorescent Sensing of IP3 with a Trifurcate Zn(II)-Containing Chemosensing Ensemble System. Org Lett 2008; 10:3539-42. [DOI: 10.1021/ol801290g] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dong Ju Oh
- Department of Chemistry and Center for Integrated Molecular Systems, Pohang University of Science and Technology (POSTECH), San 31 Hyoja-dong, Pohang 790-784, Republic of Korea
| | - Kyo Han Ahn
- Department of Chemistry and Center for Integrated Molecular Systems, Pohang University of Science and Technology (POSTECH), San 31 Hyoja-dong, Pohang 790-784, Republic of Korea
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Huang YH, Hoebe K, Sauer K. New therapeutic targets in immune disorders: ItpkB, Orai1 and UNC93B. Expert Opin Ther Targets 2008; 12:391-413. [PMID: 18348677 DOI: 10.1517/14728222.12.4.391] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Sequencing of the murine and human genomes has enabled large-scale functional genomics approaches to target identification. This holds the promise of drastically accelerating target discovery. Moreover, by providing an initial validation coincident with target identification, cell based cDNA or small interfering RNA (siRNA) screens and in particular genome-wide in vivo approaches, including forward or reverse genetics and analyses of natural gene polymorphisms, can move the relatively late step of target validation to the beginning of the process, reducing the risk of pursuing targets with little in vivo relevance. OBJECTIVE We critically discuss the value of combining functional genomics with traditional approaches for accelerating target identification and validation. METHODS We evaluate the potentials of inositol (1,4,5)trisphosphate 3-kinase B (ItpkB), Orai1 and UNC93B, three particularly interesting proteins that were recently identified through functional genomics, as targets in immune disorders. RESULTS/CONCLUSION Combining functional genomics with traditional approaches can accelerate target discovery and validation, but requires a follow-up platform that integrates and analyzes all relevant data for assessment of the clinical potential of the growing number of novel targets.
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Affiliation(s)
- Yina H Huang
- The Scripps Research Institute, Department of Immunology, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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Aoki S, Zulkefeli M, Shiro M, Kohsako M, Takeda K, Kimura E. A luminescence sensor of inositol 1,4,5-triphosphate and its model compound by ruthenium-templated assembly of a bis(Zn2+-cyclen) complex having a 2,2'-bipyridyl linker (cyclen = 1,4,7,10-tetraazacyclododecane). J Am Chem Soc 2005; 127:9129-39. [PMID: 15969591 DOI: 10.1021/ja050876b] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new supramolecular complex (Ru(Zn2L4)3) was designed and synthesized as a luminescence sensor for inositol 1,4,5-triphosphate (IP3), which is one of the important second messengers in intracellular signal transduction, and its achiral model compound, cis,cis-1,3,5-cyclohexanetriol triphosphate (CTP3), by a ruthenium(II)-templated assembly of three molecules of a bis(Zn2+-cyclen) complex having a 2,2-bipyridyl linker (Zn2L4). Single-crystal X-ray diffraction analysis of a racemic mixture of Ru(Zn2L4)3 showed that three of the six Zn2+-cyclen units are orientated to face the opposite side of the molecule with three apical ligands (Zn2+-bound HO-) of each of the three Zn2+ located on the same face. 1H NMR and UV titrations of Ru(Zn2L4)3 with CTP3 indicated that Ru(Zn2L4)3 forms a 1:2 complex with CTP3, (Ru(Zn2L4)3)-((CTP3)6-)2, in aqueous solution at neutral pH. In the absence of guest molecules, Ru(Zn2L4)3 (10 microM) has an emission maximum at 610 nm at pH 7.4 (10 mM HEPES with I = 0.1 (NaNO3)) and 25 degrees C (excitation at 300 nm). An addition of 2 equiv of CTP3 induced a 4.2-fold enhancement in the emission of Ru(Zn2L4)3 at 584 nm. In this article, we describe that Ru(Zn2L4)3 is the first chemical sensor that directly responds to CTP3 and IP3 and discriminates these triphosphates from monophosphates and diphosphates. The photodecomposition of Ru(Zn2L4)3, which is inhibited upon complexation with CTP3, and the stereoselective complexation of chiral IP3 by Ru(Zn2L4)3 are also described.
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Affiliation(s)
- Shin Aoki
- Faculty of Pharmaceutical Sciences and Center for Drug Delivery Research, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510 Japan.
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14
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Mehta G, Sen S. Fine tuning the hydrophilic–hydrophobic balance in inositols through annulation: An analysis of the hydrogen-bonded architectures of ‘annulated inositols’. CrystEngComm 2005. [DOI: 10.1039/b512911g] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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Yu J, Leibiger B, Yang SN, Caffery JJ, Shears SB, Leibiger IB, Barker CJ, Berggren PO. Cytosolic multiple inositol polyphosphate phosphatase in the regulation of cytoplasmic free Ca2+ concentration. J Biol Chem 2003; 278:46210-8. [PMID: 12963730 DOI: 10.1074/jbc.m303743200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Multiple inositol polyphosphate phosphatase (MIPP) is an enzyme that, in vitro, has the interesting property of degrading higher inositol polyphosphates to the Ca2+ second messenger, inositol 1,4,5-trisphosphate (Ins(1,4,5)P3), independently of inositol lipid breakdown. We hypothesized that a truncated cytosolic form of the largely endoplasmic reticulum-confined MIPP (cyt-MIPP) could represent an important new tool in the investigation of Ins(1,4,5)P3-dependent intracellular Ca2+ homeostasis. To optimize our ability to judge the impact of cyt-MIPP on intracellular Ca2+ concentration ([Ca2+]i) we chose a poorly responsive beta-cell line (HIT M2.2.2) with an abnormally low [Ca2+]i. Our results show for the first time in an intact mammalian cell that cyt-MIPP expression leads to a significant enhancement of Ins(1,4,5)P3 concentration. This is achieved without a significant interference from other cyt-MIPP-derived inositol phosphates. Furthermore, the low basal [Ca2+]i of these cells was raised to normal levels (35 to 115 nm) when they expressed cyt-MIPP. Noteworthy is that the normal feeble glucose-induced Ca2+ response of HIT M2.2.2 cells was enhanced dramatically by mechanisms related to this increase in basal [Ca2+]i. These data support the use of cyt-MIPP as an important tool in investigating Ins(1,4,5)P3-dependent Ca2+ homeostasis and suggest a close link between Ins(1,4,5)P3 concentration and basal [Ca2+]i, the latter being an important modulator of Ca2+ signaling in the pancreatic beta-cell.
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Affiliation(s)
- Jia Yu
- Department of Molecular Medicine, The Rolf Luft Center for Diabetes Research, L3, Karolinska Institutet, Karolinska Hospital, Stockholm SE-171 76, Sweden
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Kwon YU, Im J, Choi G, Kim YS, Choi KY, Chung SK. Synthesis of three enantiomeric pairs of scyllo-inositol phosphate and molecular interactions between all possible regioisomers of scyllo-inositol phosphate and inositol 1,4,5-trisphosphate 3-kinase. Bioorg Med Chem Lett 2003; 13:2981-4. [PMID: 12941316 DOI: 10.1016/s0960-894x(03)00629-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
scyllo-Inositol phosphates, which are among the stereoisomers of myo-inositol phosphate, can have 15 possible regioisomers including three enantiomeric pairs: scyllo-I(1,2)P(2), scyllo-I(1,2,4)P(3), scyllo-I(1,2,3,4)P(4). We herein describe the facile synthetic routes to the three enantiomeric pairs of scyllo-inositol phosphate and the molecular interactions between 15 regioisomers of scyllo-inositol phosphate and inositol 1,4,5-trisphosphate 3-kinase. Geometry of the enzyme binding site is discussed.
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Affiliation(s)
- Yong-Uk Kwon
- Department of Chemistry, Division of Molecular and Life Sciences, Pohang University of Science & Technology, Pohang 790-784, South Korea
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17
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Werry TD, Wilkinson GF, Willars GB. Mechanisms of cross-talk between G-protein-coupled receptors resulting in enhanced release of intracellular Ca2+. Biochem J 2003; 374:281-96. [PMID: 12790797 PMCID: PMC1223610 DOI: 10.1042/bj20030312] [Citation(s) in RCA: 140] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2003] [Revised: 06/03/2003] [Accepted: 06/05/2003] [Indexed: 12/21/2022]
Abstract
Alteration in [Ca(2+)](i) (the intracellular concentration of Ca(2+)) is a key regulator of many cellular processes. To allow precise regulation of [Ca(2+)](i) and a diversity of signalling by this ion, cells possess many mechanisms by which they are able to control [Ca(2+)](i) both globally and at the subcellular level. Among these are many members of the superfamily of GPCRs (G-protein-coupled receptors), which are characterized by the presence of seven transmembrane domains. Typically, those receptors able to activate PLC (phospholipase C) enzymes cause release of Ca(2+) from intracellular stores and influence Ca(2+) entry across the plasma membrane. It has been well documented that Ca(2+) signalling by one type of GPCR can be influenced by stimulation of a different type of GPCR. Indeed, many studies have demonstrated heterologous desensitization between two different PLC-coupled GPCRs. This is not surprising, given our current understanding of negative-feedback regulation and the likely shared components of the signalling pathway. However, there are also many documented examples of interactions between GPCRs, often coupling preferentially to different signalling pathways, which result in a potentiation of Ca(2+) signalling. Such interactions have important implications for both the control of cell function and the interpretation of in vitro cell-based assays. However, there is currently no single mechanism that adequately accounts for all examples of this type of cross-talk. Indeed, many studies either have not addressed this issue or have been unable to determine the mechanism(s) involved. This review seeks to explore a range of possible mechanisms to convey their potential diversity and to provide a basis for further experimental investigation.
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Affiliation(s)
- Tim D Werry
- Department of Cell Physiology and Pharmacology, Medical Sciences Building, University of Leicester, UK
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Turner H, Fleig A, Stokes A, Kinet JP, Penner R. Discrimination of intracellular calcium store subcompartments using TRPV1 (transient receptor potential channel, vanilloid subfamily member 1) release channel activity. Biochem J 2003; 371:341-50. [PMID: 12513687 PMCID: PMC1223279 DOI: 10.1042/bj20021381] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2002] [Revised: 12/05/2002] [Accepted: 01/06/2003] [Indexed: 02/06/2023]
Abstract
The store-operated calcium-release-activated calcium current, I (CRAC), is a major mechanism for calcium entry into non-excitable cells. I (CRAC) refills calcium stores and permits sustained calcium signalling. The relationship between inositol 1,4,5-trisphosphate receptor (InsP(3)R)-containing stores and I (CRAC) is not understood. A model of global InsP(3)R store depletion coupling with I (CRAC) activation may be simplistic, since intracellular stores are heterogeneous in their release and refilling activities. Here we use a ligand-gated calcium channel, TRPV1 (transient receptor potential channel, vanilloid subfamily member 1), as a new tool to probe store heterogeneity and define intracellular calcium compartments in a mast cell line. TRPV1 has activity as an intracellular release channel but does not mediate global calcium store depletion and does not invade a store coupled with I (CRAC). Intracellular TRPV1 localizes to a subset of the InsP(3)R-containing stores. TRPV1 sensitivity functionally subdivides the InsP(3)-sensitive store, as does heterogeneity in the sarcoplasmic/endoplasmic-reticulum Ca(2+)-ATPase isoforms responsible for store refilling. These results provide unequivocal evidence that a specific 'CRAC store' exists within the InsP(3)-releasable calcium stores and describe a novel methodology for manipulation of intracellular free calcium.
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Affiliation(s)
- Helen Turner
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, USA
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19
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Walker SA, Kupzig S, Lockyer PJ, Bilu S, Zharhary D, Cullen PJ. Analyzing the role of the putative inositol 1,3,4,5-tetrakisphosphate receptor GAP1IP4BP in intracellular Ca2+ homeostasis. J Biol Chem 2002; 277:48779-85. [PMID: 12356770 DOI: 10.1074/jbc.m204839200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inositol 1,3,4,5-tetrakisphosphate (IP(4)) has been linked to a potential role in the regulation of intracellular free Ca(2+) concentration ([Ca(2+)](i)) following cellular stimulation with agonists that activate phosphoinositide-specific phospholipase C. However, despite many studies, the function of IP(4) remains unclear and indeed there is still some debate over whether it has a function at all. Here we have used various molecular approaches to address whether manipulation of the potential IP(4) receptor, GAP1(IP4BP), affects [Ca(2+)](i) following cellular stimulation. Using single cell imaging, we show that the overexpression of a constitutively active and a potential dominant negative form of GAP1(IP4BP) appear to have no effect on Ca(2+) mobilization or Ca(2+) entry following stimulation of HeLa cells with histamine. In addition, through the use of small interfering RNA duplexes, we have examined the effect of suppressing endogenous GAP1(IP4BP) production on [Ca(2+)](i). In HeLa cells in which the endogenous level of GAP1(IP4BP) has been suppressed by approximately 95%, we failed to observe any effect on Ca(2+) mobilization or Ca(2+) entry following histamine stimulation. Thus, using various approaches to manipulate the function of endogenous GAP1(IP4BP) in intact HeLa cells, we have been unable to observe any detectable effect of GAP1(IP4BP) on [Ca(2+)](i).
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Affiliation(s)
- Simon A Walker
- Department of Biochemistry, Inositide Group, Integrated Signalling Laboratories, School of Medical Sciences, University of Bristol, United Kingdom
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Mishra J, Bhalla US. Simulations of inositol phosphate metabolism and its interaction with InsP(3)-mediated calcium release. Biophys J 2002; 83:1298-316. [PMID: 12202356 PMCID: PMC1302229 DOI: 10.1016/s0006-3495(02)73901-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Inositol phosphates function as second messengers for a variety of extracellular signals. Ins(1,4,5)P(3) generated by phospholipase C-mediated hydrolysis of phosphatidylinositol bisphosphate, triggers numerous cellular processes by regulating calcium release from internal stores. The Ins(1,4,5)P(3) signal is coupled to a complex metabolic cascade involving a series of phosphatases and kinases. These enzymes generate a range of inositol phosphate derivatives, many of which have signaling roles of their own. We have integrated published biochemical data to build a mass action model for InsP(3) metabolism. The model includes most inositol phosphates that are currently known to interact with each other. We have used this model to study the effects of a G-protein coupled receptor stimulus that activates phospholipase C on the inositol phosphates. We have also monitored how the metabolic cascade interacts with Ins(1,4,5)P(3)-mediated calcium release. We find temporal dynamics of most inositol phosphates to be strongly influenced by the elaborate networking. We also show that Ins(1,3,4,5)P(4) plays a key role in InsP(3) dynamics and allows for paired pulse facilitation of calcium release. Calcium oscillations produce oscillatory responses in parts of the metabolic network and are in turn temporally modulated by the metabolism of InsP(3).
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Affiliation(s)
- Jyoti Mishra
- National Centre for Biological Sciences, GKVK Campus, Bangalore 560065, India.
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Cheley S, Gu LQ, Bayley H. Stochastic sensing of nanomolar inositol 1,4,5-trisphosphate with an engineered pore. CHEMISTRY & BIOLOGY 2002; 9:829-38. [PMID: 12144927 DOI: 10.1016/s1074-5521(02)00172-2] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The introduction of a ring of arginine residues near the constriction in the transmembrane beta barrel of the staphylococcal alpha-hemolysin heptamer yielded a pore that could be almost completely blocked by phosphate anions at pH 7.5. Block did not occur with other oxyanions, including nitrate, sulfate, perchlorate, and citrate. Based on this finding, additional pores were engineered with high affinities for important cell signaling molecules, such as the Ca(2+)-mobilizing second messenger inositol 1,4,5-trisphosphate (IP(3)), that contain phosphate groups. One of these engineered pores, P(RR-2), provides a ring of fourteen arginines that project into the lumen of the transmembrane barrel. Remarkably, P(RR-2) bound IP(3) with low nanomolar affinity while failing to bind another second messenger, adenosine 3', 5'-cyclic monophosphate (cAMP). The engineered alpha-hemolysin pores may be useful as components of stochastic sensors for cell signaling molecules.
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Affiliation(s)
- Stephen Cheley
- Department of Medical Biochemistry and Genetics, The Texas A & M University System Health Science Center, College Station, TX 77843, USA.
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Abstract
Following the discovery of inositol-1,4,5-trisphosphate as a second messenger, many other inositol phosphates were discovered in quick succession, with some understanding of their synthesis pathways and a few guesses at their possible functions. But then it all seemed to go comparatively quiet, with an explosion of interest in the inositol lipids. Now the water-soluble phase is once again becoming a focus of interest. Old and new data point to a new vista of inositol phosphates, with functions in many diverse aspects of cell biology, such as ion-channel physiology, membrane dynamics and nuclear signalling.
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Affiliation(s)
- R F Irvine
- Department of Pharmacology, Tennis Court Road, Cambridge CB2 1QJ, UK.
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