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Hrabar J, Petrić M, Cavallero S, Salvemini M, D’Amelio S, Mladineo I. Rat and fish peripheral blood leukocytes respond distinctively to Anisakis pegreffii (Nematoda, Anisakidae) crude extract. Front Cell Infect Microbiol 2022; 12:1042679. [PMID: 36590595 PMCID: PMC9797851 DOI: 10.3389/fcimb.2022.1042679] [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: 09/12/2022] [Accepted: 11/18/2022] [Indexed: 12/23/2022] Open
Abstract
Infective third-stage larvae (L3) of the marine nematode Anisakis pegreffii cause inflammation and clinical symptoms in humans, their accidental host, that subside and self-resolve in a couple of weeks after L3 die. To characterise the differences in an early immune response of a marine vs. terrestrial host, we stimulated peripheral blood leukocytes (PBLs) of fish (paratenic host) and rat (accidental, human-model host) with A. pegreffii crude extract and analysed PBL transcriptomes 1 and 12 h post-stimulation. Fish and rat PBLs differentially expressed 712 and 493 transcripts, respectively, between 1 and 12 h post-stimulation (false discovery rate, FDR <0.001, logFC >2). While there was a difference in the highest upregulated transcripts between two time-points, the same Gene Ontologies, biological processes (intracellular signal transduction, DNA-dependent transcription, and DNA-regulated regulation of transcription), and molecular functions (ATP and metal ion binding) were enriched in the two hosts, showing an incrementing dynamic between 1 and 12 h. This suggests that the two distinct hosts employ qualitatively different transcript cascades only to achieve the same effect, at least during an early innate immunity response. Activation of later immunity elements and/or a combination of other host's intrinsic conditions may contribute to the death of L3 in the terrestrial host.
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Affiliation(s)
- Jerko Hrabar
- Laboratory of Aquaculture, Institute of Oceanography and Fisheries, Split, Croatia
| | - Mirela Petrić
- University Department of Marine Studies, University of Split, Split, Croatia
| | - Serena Cavallero
- Department of Public Health and Infectious Diseases, University of Rome, Sapienza, Rome, Italy
| | - Marco Salvemini
- Department of Biology, University of Naples Federico II, Naples, Italy
| | - Stefano D’Amelio
- Department of Public Health and Infectious Diseases, University of Rome, Sapienza, Rome, Italy
| | - Ivona Mladineo
- Laboratory of Functional Helminthology, Institute of Parasitology, Biology Centre of Czech Academy of Sciences, Ceske Budejovice, Czechia,*Correspondence: Ivona Mladineo,
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2
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Structural Insight into Molecular Inhibitory Mechanism of InsP 6 on African Swine Fever Virus mRNA-Decapping Enzyme g5Rp. J Virol 2022; 96:e0190521. [PMID: 35481780 PMCID: PMC9131872 DOI: 10.1128/jvi.01905-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Removal of 5′ cap on cellular mRNAs by the African swine fever virus (ASFV) decapping enzyme g5R protein (g5Rp) is beneficial to viral gene expression during the early stages of infection. As the only nucleoside diphosphate-linked moiety X (Nudix) decapping enzyme encoded in the ASFV genome, g5Rp works in both the degradation of cellular mRNA and the hydrolyzation of the diphosphoinositol polyphosphates. Here, we report the structures of dimeric g5Rp and its complex with inositol hexakisphosphate (InsP6). The two g5Rp protomers interact head to head to form a dimer, and the dimeric interface is formed by extensive polar and nonpolar interactions. Each protomer is composed of a unique N-terminal helical domain and a C-terminal classic Nudix domain. As g5Rp is an mRNA-decapping enzyme, we identified key residues, including K8, K94, K95, K98, K175, R221, and K243 located on the substrate RNA binding interfaces of g5Rp which are important to RNA binding and decapping enzyme activity. Furthermore, the g5Rp-mediated mRNA decapping was inhibited by InsP6. The g5Rp-InsP6 complex structure showed that the InsP6 molecules occupy the same regions that primarily mediate g5Rp-RNA interaction, elucidating the roles of InsP6 in the regulation of the viral decapping activity of g5Rp in mRNA degradation. Collectively, these results provide the structural basis of interaction between RNA and g5Rp and highlight the inhibitory mechanism of InsP6 on mRNA decapping by g5Rp. IMPORTANCE ASF is a highly contagious hemorrhagic viral disease in domestic pigs which causes high mortality. Currently, there are still no effective vaccines or specific drugs available against this particular virus. The protein g5Rp is the only viral mRNA-decapping enzyme, playing an essential role in the machinery assembly of mRNA regulation and translation initiation. In this study, we solved the crystal structures of g5Rp dimer and complex with InsP6. Structure-based mutagenesis studies revealed critical residues involved in a candidate RNA binding region, which also play pivotal roles in complex with InsP6. Notably, InsP6 can inhibit g5Rp activity by competitively blocking the binding of substrate mRNA to the enzyme. Our structure-function studies provide the basis for potential anti-ASFV inhibitor designs targeting the critical enzyme.
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Zhang X, Shi S, Su Y, Yang X, He S, Yang X, Wu J, Zhang J, Rao F. Suramin and NF449 are IP5K inhibitors that disrupt inositol hexakisphosphate-mediated regulation of cullin-RING ligase and sensitize cancer cells to MLN4924/pevonedistat. J Biol Chem 2020; 295:10281-10292. [PMID: 32493769 DOI: 10.1074/jbc.ra120.014375] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 05/27/2020] [Indexed: 12/27/2022] Open
Abstract
Inositol hexakisphosphate (IP6) is an abundant metabolite synthesized from inositol 1,3,4,5,6-pentakisphosphate (IP5) by the single IP5 2-kinase (IP5K). Genetic and biochemical studies have shown that IP6 usually functions as a structural cofactor in protein(s) mediating mRNA export, DNA repair, necroptosis, 3D genome organization, HIV infection, and cullin-RING ligase (CRL) deneddylation. However, it remains unknown whether pharmacological perturbation of cellular IP6 levels affects any of these processes. Here, we performed screening for small molecules that regulate human IP5K activity, revealing that the antiparasitic drug and polysulfonic compound suramin efficiently inhibits IP5K in vitro and in vivo The results from docking experiments and biochemical validations suggested that the suramin targets IP5K in a distinct bidentate manner by concurrently binding to the ATP- and IP5-binding pockets, thereby inhibiting both IP5 phosphorylation and ATP hydrolysis. NF449, a suramin analog with additional sulfonate moieties, more potently inhibited IP5K. Both suramin and NF449 disrupted IP6-dependent sequestration of CRL by the deneddylase COP9 signalosome, thereby affecting CRL activity cycle and component dynamics in an IP5K-dependent manner. Finally, nontoxic doses of suramin, NF449, or NF110 exacerbate the loss of cell viability elicited by the neddylation inhibitor and clinical trial drug MLN4924/pevonedistat, suggesting synergistic ef-fects. Suramin and its analogs provide structural templates for designing potent and specific IP5K inhibitors, which could be used in combination therapy along with MLN4924/pevonedistat. IP5K is a potential mechanistic target of suramin, accounting for suramin's therapeutic effects.
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Affiliation(s)
- Xiaozhe Zhang
- College of Biological Sciences, China Agricultural University, Beijing, China.,Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Shaodong Shi
- Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Yang Su
- Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Xiaoli Yang
- Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Sining He
- Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Xiuyan Yang
- Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Jing Wu
- Key Laboratory of Cell Differentiation and Apoptosis, Ministry of Education, Department of Pathophysiology, Ruijin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China
| | - Jian Zhang
- Key Laboratory of Cell Differentiation and Apoptosis, Ministry of Education, Department of Pathophysiology, Ruijin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China
| | - Feng Rao
- Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong, China
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4
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Brehm MA, Windhorst S. New options of cancer treatment employing InsP 6. Biochem Pharmacol 2019; 163:206-214. [PMID: 30797871 DOI: 10.1016/j.bcp.2019.02.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 02/19/2019] [Indexed: 12/21/2022]
Abstract
Many mechanistic studies have been performed to analyze the cellular functions of the highly phosphorylated molecule inositol hexakisphosphate (InsP6) in health and disease. While the physiological intracellular functions are well described, the mechanism of potential pharmacological effects on cancer cell proliferation is still controversial. There are numerous studies demonstrating that a high InsP6 concentration (≥75 µM) inhibits growth of cancer cells in vitro and in vivo. Thus, there is no doubt that InsP6 exhibits anticancer activity but the mechanism underlying the cellular effects of extracellular InsP6 on cancer cells is far from being understood. In addition, studies on the inhibitory effect of InsP6 on cancer progression in animal models ignore aspects of its bioavailability. Here, we review and critically discuss the uptake mechanism and the intracellular involvement in signaling pathways of InsP6 in cancer cells. We take into account the controversial findings on InsP6 plasma concentration, which is a critical aspect of pharmacological accessibility of InsP6 for cancer treatment. Further, we discuss novel findings with respect to the effect of InsP6 on normal and immune cells as well as on platelet aggregate size. Our goal is to stimulate further mechanistic studies into novel directions considering previously disregarded aspects of InsP6. Only when we fully understand the mechanism underlying the anticancer activity of InsP6 novel and more efficient treatment options can be developed.
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Affiliation(s)
- Maria A Brehm
- Department of Pediatric Hematology and Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sabine Windhorst
- Department of Biochemistry and Signal Transduction, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, D-20246 Hamburg, Germany.
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5
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Inositol Hexaphosphate Inhibits Proliferation and Induces Apoptosis of Colon Cancer Cells by Suppressing the AKT/mTOR Signaling Pathway. Molecules 2017; 22:molecules22101657. [PMID: 28972559 PMCID: PMC6151581 DOI: 10.3390/molecules22101657] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 09/29/2017] [Accepted: 09/29/2017] [Indexed: 01/22/2023] Open
Abstract
AKT, a serine/threonine protein kinase and mammalian target of rapamycin (mTOR) plays a critical role in the proliferation and resistance to apoptosis that are essential to the development and progression of colon cancer. Therefore, AKT/mTOR signaling pathway has been recognized as an attractive target for anticancer therapy. Inositol hexaphosphate (InsP6), a natural occurring phytochemical, has been shown to have both preventive and therapeutic effects against various cancers, however, its exact molecular mechanisms of action are not fully understood. The aim of the in vitro study was to investigate the anticancer activity of InsP6 on colon cancer with the focus on inhibiting the AKT1 kinase and p70S6K1 as mTOR effector, in relation to proliferation and apoptosis of cells. The colon cancer Caco-2 cells were cultured using standard techniques and exposed to InsP6 at different concentrations (1 mM, 2.5 mM and 5 mM). Cellular proliferative activity was monitored by 5-bromo-2′-deoxyuridine (BrdU) incorporation into cellular DNA. Flow cytometric analysis was performed for cell cycle progression and apoptosis studies. Real-time RT-qPCR was used to validate mRNA levels of CDNK1A, CDNK1B, CASP3, CASP9, AKT1 and S6K1 genes. The concentration of p21 protein as well as the activities of caspase 3, AKT1 and p70S6K1 were determined by the ELISA method. The results revealed that IP6 inhibited proliferation and stimulated apoptosis of colon cancer cells. This effect was mediated by an increase in the expression of genes encoding p21, p27, caspase 3, caspase 9 as well a decrease in transcription of AKT1 and S6K1. InsP6 suppressed phosphorylation of AKT1 and p70S6K1, downstream effector of mTOR. Based on these studies it may be concluded that InsP6 can reduce proliferation and induce apoptosis through inhibition of the AKT/mTOR pathway and mTOR effector followed by modulation of the expression and activity of several key components of these pathways in colon cancer cells.
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Lee JK, Jansson ET, Nam HG, Zare RN. High-Resolution Live-Cell Imaging and Analysis by Laser Desorption/Ionization Droplet Delivery Mass Spectrometry. Anal Chem 2016; 88:5453-61. [PMID: 27110027 PMCID: PMC5446058 DOI: 10.1021/acs.analchem.6b00881] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have developed a new ambient-ionization mass spectrometric technique named laser desorption/ionization droplet delivery mass spectrometry (LDIDD-MS). LDIDD-MS permits high-resolution, high-sensitivity imaging of tissue samples as well as measurements of both single-cell apoptosis and live-cell exocytosis. A pulsed (15 Hz) UV laser beam (266 nm) is focused on a surface covered with target analytes to trigger their desorption and ionization. A spray of liquid droplets is simultaneously directed onto the laser-focused surface region to capture the ionized analytes and deliver them to a mass spectrometer. The approach of rapid and effective capturing of molecules after laser desorption/ionization allows the limit of detection for the amino acid lysine to be as low as 2 amol under ambient ionization conditions. Two-dimensional maps of the desorbed/ionized species are recorded by moving the sample on an XY translational stage. The spatial resolution for imaging with LDIDD-MS was determined to be 2.4 μm for an ink-printed pattern and 3 μm for mouse brain tissue. We applied LDIDD-MS to single-cell analysis of apoptotic HEK cells. Differences were observed in the profiles of fatty acids and lipids between healthy HEK cells and those undergoing apoptosis. We observed upregulation of phosphatidylcholine (PC) with a relatively shorter carbon chain length and downregulation of PC with a relatively longer carbon chain length. We also applied LDIDD-MS for a real-time direct measurements of live-cell exocytosis. The catecholamine dopamine and trace amines (phenethylamine and tyramine) were detected from live PC12 cells without damaging them.
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Affiliation(s)
- Jae Kyoo Lee
- Department of Chemistry, Stanford University, Stanford, California 94305 United States
| | - Erik T. Jansson
- Department of Chemistry, Stanford University, Stanford, California 94305 United States
- Department of Chemistry – BMC, Uppsala University, SE-75124 Uppsala, Sweden
| | - Hong Gil Nam
- Center for Plant Aging Research, Institute for Basic Science, Daegu 711-873, Republic of Korea
- Department of New Biology, DGIST, Daegu 711-873, Republic of Korea
| | - Richard N. Zare
- Department of Chemistry, Stanford University, Stanford, California 94305 United States
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Zhang Z, Hou L, Li X, Ju C, Zhang J, Li X, Wang X, Liu C, Lv Y, Wang Y. Neuroprotection of inositol hexaphosphate and changes of mitochondrion mediated apoptotic pathway and α-synuclein aggregation in 6-OHDA induced parkinson's disease cell model. Brain Res 2015; 1633:87-95. [PMID: 26740400 DOI: 10.1016/j.brainres.2015.12.035] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 12/07/2015] [Accepted: 12/18/2015] [Indexed: 12/19/2022]
Abstract
Animal and cell experiments showed that inositol hexaphosphate (IP6) was protective on neurons in parkinson's disease (PD) model, but the underlying mechanism of this action was not extensively elucidated. To address this question, we established 6-hydroxydopamine (6-OHDA) induced human dopaminergic cell line SH-SY5Y as PD cell model and testified the neuroprotection of IP6. Through hoechst nuclear stain method and flow cytometric analysis, apoptosis induced by 6-OHDA was blocked by IP6 pretreatment. Significant protection against reactive oxygen species (ROS) and lipid peroxidation product malondialdehyde (MDA) was observed in 6-OHDA induced cells pretreated with IP6. To further investigate the mechanism of anti-apoptotic effect of IP6, expression of mediators in mitochondrion dependent apoptotic pathway was detected. Results indicated that loss of mitochondrial membrane potential, cytochrome c releasing, upregulation of Bcl-2-associated X protein (Bax), downregulation of B-cell CLL/lymphoma 2 (Bcl-2) and caspases activation were reversed by IP6. In addition, using flow cytometric method and western blot approach, our data showed that IP6 attenuated the rise of calcium and α-synuclein aggregation in cytosol. Collectively, IP6 exerted its neuroprotection on dopaminergic cells in PD cell model and the mechanism may be associated with changes of mitochondrion mediated apoptotic pathway and α-synuclein aggregation.
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Affiliation(s)
- Zheng Zhang
- Department of Biochemistry and Molecular Biology, Medical College of Qingdao University, Qingdao, Shandong Province, China
| | - Lin Hou
- Department of Biochemistry and Molecular Biology, Medical College of Qingdao University, Qingdao, Shandong Province, China.
| | - Xianghong Li
- Department of Neonatology, Affiliated Hospital of Qingdao University, Qingdao, Shandong Province, China
| | - Chuanxia Ju
- Department of Pharmacology, Medical College of Qingdao University, Qingdao, Shandong Province, China
| | - Jinyu Zhang
- Department of Biochemistry and Molecular Biology, Medical College of Qingdao University, Qingdao, Shandong Province, China
| | - Xin Li
- Experiment Center of Biochemistry and Molecular Biology, Medical College of Qingdao University, Qingdao, Shandong Province, China
| | - Xiuli Wang
- Experiment Center of Biochemistry and Molecular Biology, Medical College of Qingdao University, Qingdao, Shandong Province, China
| | - Cun Liu
- Laboratory Department of the Third People׳s Hospital of Qingdao, Qingdao, Shandong Province, China
| | - Yuqiang Lv
- Department of Biochemistry and Molecular Biology, Medical College of Qingdao University, Qingdao, Shandong Province, China
| | - Yuehua Wang
- Department of Biochemistry and Molecular Biology, Medical College of Qingdao University, Qingdao, Shandong Province, China
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8
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Inositol phosphate kinase 2 is required for imaginal disc development in Drosophila. Proc Natl Acad Sci U S A 2015; 112:15660-5. [PMID: 26647185 DOI: 10.1073/pnas.1514684112] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Inositol phosphate kinase 2 (Ipk2), also known as IP multikinase IPMK, is an evolutionarily conserved protein that initiates production of inositol phosphate intracellular messengers (IPs), which are critical for regulating nuclear and cytoplasmic processes. Here we report that Ipk2 kinase activity is required for the development of the adult fruit fly epidermis. Ipk2 mutants show impaired development of their imaginal discs, the primordial tissues that form the adult epidermis. Although disk tissue seems to specify normally during early embryogenesis, loss of Ipk2 activity results in increased apoptosis and impairment of proliferation during larval and pupal development. The proliferation defect is in part attributed to a reduction in JAK/STAT signaling, possibly by controlling production or secretion of the pathway's activating ligand, Unpaired. Constitutive activation of the JAK/STAT pathway downstream of Unpaired partially rescues the disk growth defects in Ipk2 mutants. Thus, IP production is essential for proliferation of the imaginal discs, in part, by regulating JAK/STAT signaling. Our work demonstrates an essential role for Ipk2 in producing inositide messengers required for imaginal disk tissue maturation and subsequent formation of adult body structures and provides molecular insights to signaling pathways involved in tissue growth and stability during development.
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Bang S, Chen Y, Ahima RS, Kim SF. Convergence of IPMK and LKB1-AMPK signaling pathways on metformin action. Mol Endocrinol 2014; 28:1186-93. [PMID: 24877601 DOI: 10.1210/me.2014-1134] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Metformin is a biguanide drug that is widely prescribed for type 2 diabetes. Metformin suppresses hepatic gluconeogenesis and increases fatty acid oxidation. Although studies have suggested that metformin acts, at least in part, via activation of the liver kinase B1 (LKB1)/AMP-activated protein kinase (AMPK) pathway, the specific molecular mechanisms underlying metformin's regulation of glucose and lipid metabolism have not been well delineated. Recently, we have shown that inositol polyphosphate multikinase (IPMK) plays an important role in cellular energy metabolism and glucose-mediated AMPK regulation. Here we investigated the role of IPMK in metformin-induced AMPK activation. We observed that metformin-mediated activation of AMPK was impaired in the absence of IPMK. Overexpression of wild-type IPMK was sufficient to restore LKB1-AMPK activation by either metformin or AICAR in IPMK(-/-) murine embryonic fibroblast cells, suggesting that IPMK may act as an upstream regulator of LKB1-AMPK signaling in response to metformin. Moreover, this regulation was mediated by protein-protein interaction between IPMK and LKB1 as a dominant-negative peptide, which abrogates this interaction, attenuated metformin's ability to activate AMPK. Our data demonstrate that IPMK plays an important role in LKB1/AMPK signaling and may be targeted for treatment of metabolic diseases.
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Affiliation(s)
- Sookhee Bang
- Department of Psychiatry and Pharmacology, Center for Neurobiology and Behavior (S.B., Y.C., S.F.K.); and Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism and the Institute for Diabetes, Obesity, and Metabolism (R.S.A.), Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
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Gosein V, Miller GJ. Conformational stability of inositol 1,3,4,5,6-pentakisphosphate 2-kinase (IPK1) dictates its substrate selectivity. J Biol Chem 2013; 288:36788-95. [PMID: 24165122 DOI: 10.1074/jbc.m113.512731] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inositol 1,3,4,5,6-pentakisphosphate 2-kinase (IPK1) converts inositol 1,3,4,5,6-pentakisphosphate(IP5) to inositol hexakisphosphate (IP6). IPK1 shares structural similarity with protein kinases and is suspected to employ a similar mechanism of activation. Previous studies revealed roles for the 1- and 3-phosphates of IP5 in IPK1 activation and revealed that the N-lobe of IPK1 is unstable in the absence of inositol phosphate (IP). Here, we demonstrate the link between IPK1 substrate specificity and the stability of its N-lobe. Limited proteolysis of IPK1 revealed that N-lobe stability is dependent on the presence of the 1-phosphate of the substrate, whereas overall stability of IPK1 was increased in ternary complexes with nucleotide and IPs possessing 1- and 3-phosphates that engage the N-lobe of IPK1. Thus, the 1- and 3-phosphates possess dual roles in both IPK1 activation and IPK1 stability. To test whether kinase stability directly contributed to substrate selectivity of the kinase, we engineered IPK1 mutants with disulfide bonds that artificially stabilized the N-lobe in an IP-independent manner thereby mimicking its substrate-bound state in the absence of IP. IPK1 E82C/S142C exhibited a DTT-sensitive 5-fold increase in kcat for 3,4,5,6-inositol tetrakisphosphate (3,4,5,6-IP4) as compared with wild-type IPK1. The crystal structure of the IPK1 E82C/S142C mutant confirmed the presence of the disulfide bond and revealed a small shift in the N-lobe. Finally, we determined that IPK1 E82C/S142C is substantially more stable than wild-type IPK1 under nonreducing conditions, revealing that increased stability of IPK1 E82C/S142C correlates with changes in substrate specificity by allowing IPs lacking the stabilizing 1-phosphate to be used. Taken together, our results show that IPK1 substrate selection is linked to the ability of each potential substrate to stabilize IPK1.
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Affiliation(s)
- Varin Gosein
- From the Department of Pharmacology and Therapeutics, McGill University, Montréal, Quebec H3G 1Y6, Canada
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Loss O, Wu CT, Riccio A, Saiardi A. Modulation of inositol polyphosphate levels regulates neuronal differentiation. Mol Biol Cell 2013; 24:2981-9. [PMID: 23864704 PMCID: PMC3771958 DOI: 10.1091/mbc.e13-04-0198] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The modulation of inositol pentakisphosphate (IP5) and hexakisphosphate (IP6) intracellular levels controls the differentiation and survival of PC12 cells and primary neurons. These mechanisms are controlled by the levels of the protein kinase IP5-2K responsible for the conversion of IP5 into IP6. The binding of neurotrophins to tropomyosin receptor kinase receptors initiates several signaling pathways, including the activation of phospholipase C-γ, which promotes the release of diacylglycerol and inositol 1,4,5-trisphosphate (IP3). In addition to recycling back to inositol, IP3 serves as a precursor for the synthesis of higher phosphorylated inositols, such as inositol 1,3,4,5,6-pentakisphosphate (IP5) and inositol hexakisphosphate (IP6). Previous studies on the effect of neurotrophins on inositol signaling were limited to the analysis of IP3 and its dephosphorylation products. Here we demonstrate that nerve growth factor (NGF) regulates the levels of IP5 and IP6 during PC12 differentiation. Furthermore, both NGF and brain-derived neurotrophic factor alter IP5 and IP6 intracellular ratio in differentiated PC12 cells and primary neurons. Neurotrophins specifically regulate the expression of IP5-2 kinase (IP5-2K), which phosphorylates IP5 into IP6. IP5-2K is rapidly induced after NGF treatment, but its transcriptional levels sharply decrease in fully differentiated PC12 cells. Reduction of IP5-2K protein levels by small interfering RNA has an effect on the early stages of PC12 cell differentiation, whereas fully differentiated cells are not affected. Conversely, perturbation of IP5-2K levels by overexpression suggests that both differentiated PC12 cells and sympathetic neurons require low levels of the enzyme for survival. Therefore maintaining appropriate intracellular levels of inositol polyphosphates is necessary for neuronal survival and differentiation.
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Affiliation(s)
- Omar Loss
- Cell Biology Unit and Laboratory for Molecular Cell Biology, Medical Research Council, University College London, London WC1E 6BT, United Kingdom Department of Cell and Developmental Biology, University College London, London WC1E 6BT, United Kingdom Department of Neuroscience, University College London, London WC1E 6BT, United Kingdom
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12
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Vaniotis G, Del Duca D, Trieu P, Rohlicek CV, Hébert TE, Allen BG. Nuclear β-adrenergic receptors modulate gene expression in adult rat heart. Cell Signal 2010; 23:89-98. [PMID: 20732414 DOI: 10.1016/j.cellsig.2010.08.007] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 08/05/2010] [Accepted: 08/16/2010] [Indexed: 01/26/2023]
Abstract
Both β(1)- and β(3)-adrenergic receptors (β(1)ARs and β(3)ARs) are present on nuclear membranes in adult ventricular myocytes. These nuclear-localized receptors are functional with respect to ligand binding and effector activation. In isolated cardiac nuclei, the non-selective βAR agonist isoproterenol stimulated de novo RNA synthesis measured using assays of transcription initiation (Boivin et al., 2006 Cardiovasc Res. 71:69-78). In contrast, stimulation of endothelin receptors, another G protein-coupled receptor (GPCR) that localizes to the nuclear membrane, resulted in decreased RNA synthesis. To investigate the signalling pathway(s) involved in GPCR-mediated regulation of RNA synthesis, nuclei were isolated from intact adult rat hearts and treated with receptor agonists in the presence or absence of inhibitors of different mitogen-activated protein kinase (MAPK) and PI3K/PKB pathways. Components of p38, JNK, and ERK1/2 MAP kinase cascades as well as PKB were detected in nuclear preparations. Inhibition of PKB with triciribine, in the presence of isoproterenol, converted the activation of the βAR from stimulatory to inhibitory with regards to RNA synthesis, while ERK1/2, JNK and p38 inhibition reduced both basal and isoproterenol-stimulated activity. Analysis by qPCR indicated an increase in the expression of 18S rRNA following isoproterenol treatment and a decrease in NFκB mRNA. Further qPCR experiments revealed that isoproterenol treatment also reduced the expression of several other genes involved in the activation of NFκB, while ERK1/2 and PKB inhibition substantially reversed this effect. Our results suggest that GPCRs on the nuclear membrane regulate nuclear functions such as gene expression and this process is modulated by activation/inhibition of downstream protein kinases within the nucleus.
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Affiliation(s)
- George Vaniotis
- Department of Biochemistry, Université de Montréal, Montréal, Québec, Canada
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Wang YH, Ahmar H, Irving HR. Induction of apoptosis by plant natriuretic peptides in rat cardiomyoblasts. Peptides 2010; 31:1213-8. [PMID: 20307601 DOI: 10.1016/j.peptides.2010.03.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Revised: 03/08/2010] [Accepted: 03/08/2010] [Indexed: 11/21/2022]
Abstract
Atrial natriuretic peptide (ANP) has an important role in maintaining the homeostasis of body fluids and blood pressure and also in preventing cardiac hypertrophy and initiating the process of apoptosis. An immunoreactive analog of ANP was discovered in plants over a decade ago and termed plant natriuretic peptide (PNP). PNP is a small protein that contains sequence and structural similarity to ANP within a predicted protruding psi (psi) loop. Since application of ANP or PNP stimulates similar functional effects in plants, it is conceivable that PNP may have effects on mammalian cells. In this report, we show that purified recombinant PNP induces apoptosis in a dose dependent and cell type specific manner. Rat cardiac myoblasts (H9c2 cells) were more susceptible to the apoptotic promoting effects of PNP and ANP than HEK-293T cells where PNP had a protective effect at lower concentrations. Similarly rat thoracic myoblasts (A-10) were less responsive to both PNP and ANP than the H9c2 cells. Since PNP is mimicking the effect of ANP in this instance, PNP may prove to be a useful lead molecule for developing novel therapeutic natriuretic peptides.
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Affiliation(s)
- Yu Hua Wang
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
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14
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Branschädel M, Aird A, Zappe A, Tietz C, Krippner-Heidenreich A, Scheurich P. Dual function of cysteine rich domain (CRD) 1 of TNF receptor type 1: Conformational stabilization of CRD2 and control of receptor responsiveness. Cell Signal 2010; 22:404-14. [DOI: 10.1016/j.cellsig.2009.10.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Accepted: 10/21/2009] [Indexed: 11/26/2022]
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15
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Eberhard M, Föller M, Lang F. Effect of phytic acid on suicidal erythrocyte death. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:2028-2033. [PMID: 20058927 DOI: 10.1021/jf903666b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Phytic acid, an anticarcinogenic food component, stimulates apoptosis of tumor cells. Similar to apoptosis, human erythrocytes may undergo suicidal death or eryptosis, characterized by cell membrane scrambling and cell shrinkage. Triggers of eryptosis include energy depletion. Phytate intake could cause anemia, an effect attributed to iron complexation. The present experiments explored whether phytic acid influences eryptosis. Supernatant hemoglobin concentration was determined to reveal hemolysis, annexin V-binding in FACS analysis was utilized to identify erythrocytes with scrambled cell membrane, forward scatter in FACS analysis was taken as a measure of cell volume, and a luciferin-luciferase assay was employed to determine erythrocyte ATP content. As a result, phytic acid (>or=1 mM) did not lead to significant hemolysis, but significantly increased the percentage of annexin V-binding erythrocytes, significantly decreased forward scatter, and significantly decreased cellular ATP content. In conclusion, phytic acid stimulates suicidal human erythrocyte death, an effect paralleling its proapoptotic effect on nucleated cells.
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Affiliation(s)
- Matthias Eberhard
- Department of Physiology, Eberhard-Karls-University of Tubingen, Gmelinstrasse 5, D-72076 Tuebingen, Germany
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16
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Tsui MM, York JD. Roles of inositol phosphates and inositol pyrophosphates in development, cell signaling and nuclear processes. ACTA ACUST UNITED AC 2009; 50:324-37. [PMID: 20006638 DOI: 10.1016/j.advenzreg.2009.12.002] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Marco M Tsui
- Department of Pharmacology and Cancer Biology, Howard Hughes Medical Institute, Duke University Medical Center, Box 3813, Durham, NC 27710, USA
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Traynor-Kaplan AE, Moody M, Nur M, Gabriel S, Majerus PW, Drumm ML, Langton-Webster B. INO-4995 therapeutic efficacy is enhanced with repeat dosing in cystic fibrosis knockout mice and human epithelia. Am J Respir Cell Mol Biol 2009; 42:105-12. [PMID: 19346319 PMCID: PMC2809217 DOI: 10.1165/rcmb.2008-0380oc] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Progressive lung damage in cystic fibrosis (CF) has been linked to inadequate airway mucosal hydration. We previously demonstrated that an inositol tetrakisphosphate analog, 1-O-octyl-2-O-butyryl-myo-inositol 3,4,5,6-tetrakisphosphate octakis(propionoxymethyl)ester (INO-4995), regulates airway secretory and absorptive processes, affecting mucosal hydration by prolonged (24 h) inhibition of Na(+) and fluid absorption in CF human nasal epithelia (CFHNE). The objectives of this study were to further assess clinical potential of INO-4995 in CF through ascertaining in vivo activity in mice with CF, determining the effects of repeated administration on potency and determining cytoplasmic half-life. Uptake and metabolism of [(3)H]INO-4995 was monitored with HPLC to calculate intracellular half-life. INO-4995 was administered in vitro repeatedly over 4 to 8 days to CFHNE. Fluid absorption was assessed by blue dextran exclusion, and basal short-circuit current was measured in Ussing chambers. INO-4995 (1-100 microg/kg) was dosed intranasally either as a single dose or once per day over 4 days to gut-corrected CF mice. [(3)H]INO-4995 was rapidly taken up by epithelial cultures and converted to the active drug, which had a half-life of 40 hours. Repeated daily application of INO-4995 to CFHNE lowered the effective concentration for inhibition of fluid absorption and amiloride-sensitive short-circuit current in cultured CFHNE, and reduced nasal potential difference to nearly control levels in gut-corrected CF mice. Ca(2+)-activated Cl(-) channel activity was also boosted in cultures. Mouse nasal levels fell from abnormal levels to within 2 muA of normal with repeated exposure to 0.8 microg/kg over 4 days. These data support further development of INO-4995 for the treatment of CF.
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Liu X, Villalta PW, Sturla SJ. Simultaneous determination of inositol and inositol phosphates in complex biological matrices: quantitative ion-exchange chromatography/tandem mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2009; 23:705-712. [PMID: 19191261 DOI: 10.1002/rcm.3923] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
myo-Inositol (Ins) and myo-inositol phosphates (InsPs) are widely distributed in plants and animals. The evaluation of the distribution of Ins and InsPs in cells and plant sources can impact the understanding of their role in nutrition, cellular processes and diseases, and how they may be modulated by diet. We developed an anion-exchange chromatography/tandem mass spectrometry (HPLC/ESI-MS/MS) method for the separation and simultaneous quantitation of Ins and different naturally occurring phosphorylated inositol compounds. Chromatographic separation was achieved in 30 min on a commercial anion-exchange column (0.5 x 150 mm) using a gradient of 200 mM ammonium carbonate buffer (pH 9.0) and 5% methanol in H(2)O. Analytes were identified by selective reaction monitoring using a triple quadrupole mass spectrometer in negative ion electrospray ionization mode. Adenosine 5'-monophosphate was used as a general internal standard for quantitation. Detection is linear in the range of 0.25-400 pmol for Ins, InsP(1), InsP(4), and InsP(5), 40-400 pmol for InsP(2) and InsP(3), and 60-400 pmol for InsP(6), with a minimum r(2) > 0.994. The limit of detection is 0.25 pmol with a signal-to-noise ratio of 10:1 for all analytes. The intra-day and inter-day variations were within 17% at three concentration levels. Recovery values for the seven analytes spiked into extraction solution or different matrices were between 63 and 121%. Using this approach, Ins and InsPs were measured in three different plant samples and in cultured cells, illustrating significant differences in the distribution of inositol compounds in food samples compared to cells and between cell types.
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Affiliation(s)
- Xiaodan Liu
- Department of Medicinal Chemistry, College of Pharmacy, University of Minnesota, Minneapolis, MN 55455, USA
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19
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Murphy AM, Otto B, Brearley CA, Carr JP, Hanke DE. A role for inositol hexakisphosphate in the maintenance of basal resistance to plant pathogens. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 56:638-52. [PMID: 18643983 DOI: 10.1111/j.1365-313x.2008.03629.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Phytic acid (myo-inositol hexakisphosphate, InsP6) is an important phosphate store and signal molecule in plants. However, low-phytate plants are being developed to minimize the negative health effects of dietary InsP6 and pollution caused by undigested InsP6 in animal waste. InsP6 levels were diminished in transgenic potato plants constitutively expressing an antisense gene sequence for myo-inositol 3-phosphate synthase (IPS, catalysing the first step in InsP6 biosynthesis) or Escherichia coli polyphosphate kinase. These plants were less resistant to the avirulent pathogen potato virus Y and the virulent pathogen tobacco mosaic virus (TMV). In Arabidopsis thaliana, mutation of the gene for the enzyme catalysing the final step of InsP6 biosynthesis (InsP5 2-kinase) also diminished InsP6 levels and enhanced susceptibility to TMV and to virulent and avirulent strains of the bacterial pathogen Pseudomonas syringae. Arabidopsis thaliana has three IPS genes (AtIPS1-3). Mutant atips2 plants were depleted in InsP6 and were hypersusceptible to TMV, turnip mosaic virus, cucumber mosaic virus and cauliflower mosaic virus as well as to the fungus Botrytis cinerea and to P. syringae. Mutant atips2 and atipk1 plants were as hypersusceptible to infection as plants unable to accumulate salicylic acid (SA) but their increased susceptibility was not due to reduced levels of SA. In contrast, mutant atips1 plants, which were also depleted in InsP6, were not compromised in resistance to pathogens, suggesting that a specific pool of InsP6 regulates defence against phytopathogens.
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MESH Headings
- Arabidopsis/genetics
- Arabidopsis/metabolism
- Arabidopsis/microbiology
- Arabidopsis/virology
- Arabidopsis Proteins/genetics
- Arabidopsis Proteins/metabolism
- Botrytis/pathogenicity
- Caulimovirus/pathogenicity
- Cucumovirus/pathogenicity
- DNA, Bacterial/genetics
- Disease Susceptibility/microbiology
- Disease Susceptibility/virology
- Gene Expression Regulation, Plant
- Genes, Plant
- Immunity, Innate/genetics
- Mutagenesis, Insertional
- Mutation
- Myo-Inositol-1-Phosphate Synthase/genetics
- Myo-Inositol-1-Phosphate Synthase/metabolism
- Phosphotransferases (Alcohol Group Acceptor)/genetics
- Phosphotransferases (Alcohol Group Acceptor)/metabolism
- Phytic Acid/biosynthesis
- Plant Diseases/genetics
- Plant Diseases/microbiology
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Plants, Genetically Modified/genetics
- Plants, Genetically Modified/metabolism
- Plants, Genetically Modified/microbiology
- Plants, Genetically Modified/virology
- Potyvirus/pathogenicity
- Pseudomonas syringae/pathogenicity
- RNA, Plant/genetics
- Salicylic Acid/metabolism
- Signal Transduction
- Solanum tuberosum/genetics
- Solanum tuberosum/metabolism
- Solanum tuberosum/virology
- Tobacco Mosaic Virus/pathogenicity
- Tymovirus/pathogenicity
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Affiliation(s)
- Alex M Murphy
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
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Majerus PW, Zou J, Marjanovic J, Kisseleva MV, Wilson MP. The role of inositol signaling in the control of apoptosis. ACTA ACUST UNITED AC 2008; 48:10-7. [PMID: 18486622 DOI: 10.1016/j.advenzreg.2008.04.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Philip W Majerus
- Division of Hematology, Washington University School of Medicine, 660 South Euclid, St. Louis, MO 63110, United States.
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21
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Yang L, Reece JM, Cho J, Bortner CD, Shears SB. The nucleolus exhibits an osmotically regulated gatekeeping activity that controls the spatial dynamics and functions of nucleolin. J Biol Chem 2008; 283:11823-31. [PMID: 18299322 PMCID: PMC2431058 DOI: 10.1074/jbc.m800308200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Revised: 02/15/2008] [Indexed: 12/17/2022] Open
Abstract
We demonstrate that physiologically relevant perturbations in the osmotic environment rheostatically regulate a gatekeeping function for the nucleolus that controls the spatial dynamics and functions of nucleolin. HeLa cells and U2-OS osteosarcoma cells were osmotically challenged with 100-200 mm sorbitol, and the intranuclear distribution of nucleolin was monitored by confocal microscopy. Nucleolin that normally resides in the innermost fibrillar core of the nucleolus, where it assists rDNA transcription and replication, was expelled within 30 min of sorbitol addition. The nucleolin was transferred into the nucleoplasm, but it distributed there non-uniformly; locally high levels accumulated in 4',6-diamidino-2-phenylindole-negative zones containing euchromatic (transcriptionally active) DNA. Inositol pyrophosphates also responded within 30 min of hyperosmotic stress: levels of bisdiphosphoinositol tetrakisphosphate increased 6-fold, and this was matched by decreased levels of its precursor, diphosphoinositol pentakisphosphate. Such fluctuations in inositol pyrophosphate levels are of considerable interest, because, according to previously published in vitro data, they regulate the degree of phosphorylation of nucleolin through a novel kinase-independent phosphotransferase reaction ( Saiardi, A., Bhandari, A., Resnick, R., Cain, A., Snowman, A. M., and Snyder, S. H. (2004) Science 306, 2101-2105 ). However, by pharmacologically intervening in inositol pyrophosphate metabolism, we found that it did not supervise the osmotically driven switch in the biological activities of nucleolin in vivo.
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Affiliation(s)
- Ling Yang
- Inositol Signaling Group and
the Molecular Endocrinology Group,
NIEHS, National Institutes of Health, Department of Health and Human Services,
Research Triangle Park, North Carolina 27709 and
Reecent Technologies, LLC, Durham,
North Carolina 27713
| | - Jeff M. Reece
- Inositol Signaling Group and
the Molecular Endocrinology Group,
NIEHS, National Institutes of Health, Department of Health and Human Services,
Research Triangle Park, North Carolina 27709 and
Reecent Technologies, LLC, Durham,
North Carolina 27713
| | - Jaiesoon Cho
- Inositol Signaling Group and
the Molecular Endocrinology Group,
NIEHS, National Institutes of Health, Department of Health and Human Services,
Research Triangle Park, North Carolina 27709 and
Reecent Technologies, LLC, Durham,
North Carolina 27713
| | - Carl D. Bortner
- Inositol Signaling Group and
the Molecular Endocrinology Group,
NIEHS, National Institutes of Health, Department of Health and Human Services,
Research Triangle Park, North Carolina 27709 and
Reecent Technologies, LLC, Durham,
North Carolina 27713
| | - Stephen B. Shears
- Inositol Signaling Group and
the Molecular Endocrinology Group,
NIEHS, National Institutes of Health, Department of Health and Human Services,
Research Triangle Park, North Carolina 27709 and
Reecent Technologies, LLC, Durham,
North Carolina 27713
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22
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Brehm M, Schenk T, Zhou X, Fanick W, Lin H, Windhorst S, Nalaskowski M, Kobras M, Shears S, Mayr G. Intracellular localization of human Ins(1,3,4,5,6)P5 2-kinase. Biochem J 2007; 408:335-45. [PMID: 17705785 PMCID: PMC2267366 DOI: 10.1042/bj20070382] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Revised: 07/18/2007] [Accepted: 08/17/2007] [Indexed: 01/05/2023]
Abstract
InsP6 is an intracellular signal with several proposed functions that is synthesized by IP5K [Ins(1,3,4,5,6)P5 2-kinase]. In the present study, we overexpressed EGFP (enhanced green fluorescent protein)-IP5K fusion proteins in NRK (normal rat kidney), COS7 and H1299 cells. The results indicate that there is spatial microheterogeneity in the intracellular localization of IP5K that could also be confirmed for the endogenous enzyme. This may facilitate changes in InsP6 levels at its sites of action. For example, overexpressed IP5K showed a structured organization within the nucleus. The kinase was preferentially localized in euchromatin and nucleoli, and co-localized with mRNA. In the cytoplasm, the overexpressed IP5K showed locally high concentrations in discrete foci. The latter were attributed to stress granules by using mRNA, PABP [poly(A)-binding protein] and TIAR (TIA-1-related protein) as markers. The incidence of stress granules, in which IP5K remained highly concentrated, was further increased by puromycin treatment. Using FRAP (fluorescence recovery after photobleaching) we established that IP5K was actively transported into the nucleus. By site-directed mutagenesis we identified a nuclear import signal and a peptide segment mediating the nuclear export of IP5K.
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Key Words
- euchromatin
- ins(1,3,4,5,6)p5 2-kinase (ip5k)
- in situ hybridization
- nuclear localization
- stress granule
- dapi, 4′,6-diamidino-2-phenylindole
- dtt, dithiothreitol
- egfp, enhanced green fluorescent protein
- fish, fluorescence in situ hybridization
- frap, fluorescence recover after photobleaching
- ipmk, inositol phosphate multikinase
- ipk, inositol phosphate kinase
- ip3k, ins(1,4,5)p3 3-kinase
- ip5k, ins(1,3,4,5,6)p5 2-kinase
- lmb, leptomycin b
- mdd-hplc, metal-dye-detection-hplc
- mrnp, messenger ribonucleoprotein
- nls, nuclear localization sequence
- nrk, normal rat kidney
- orf, open reading frame
- pabp, poly(a)-binding protein
- rnai, rna interference
- roi, region of interest
- sg, stress granule
- sirna, small-interfering rna
- tiar, tia-1-related protein
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Affiliation(s)
- Maria A. Brehm
- *NIEHS/NIH, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, U.S.A
| | - Tobias M. H. Schenk
- †Universitätsklinikum Hamburg-Eppendorf, Institut für Medizinische Biochemie und Molekularbiologie I: Zelluläre Signaltransduktion, Martinistraße 52, 20246 Hamburg, Germany
| | - Xuefei Zhou
- †Universitätsklinikum Hamburg-Eppendorf, Institut für Medizinische Biochemie und Molekularbiologie I: Zelluläre Signaltransduktion, Martinistraße 52, 20246 Hamburg, Germany
| | - Werner Fanick
- †Universitätsklinikum Hamburg-Eppendorf, Institut für Medizinische Biochemie und Molekularbiologie I: Zelluläre Signaltransduktion, Martinistraße 52, 20246 Hamburg, Germany
| | - Hongying Lin
- †Universitätsklinikum Hamburg-Eppendorf, Institut für Medizinische Biochemie und Molekularbiologie I: Zelluläre Signaltransduktion, Martinistraße 52, 20246 Hamburg, Germany
| | - Sabine Windhorst
- †Universitätsklinikum Hamburg-Eppendorf, Institut für Medizinische Biochemie und Molekularbiologie I: Zelluläre Signaltransduktion, Martinistraße 52, 20246 Hamburg, Germany
| | - Marcus M. Nalaskowski
- †Universitätsklinikum Hamburg-Eppendorf, Institut für Medizinische Biochemie und Molekularbiologie I: Zelluläre Signaltransduktion, Martinistraße 52, 20246 Hamburg, Germany
| | - Mario Kobras
- †Universitätsklinikum Hamburg-Eppendorf, Institut für Medizinische Biochemie und Molekularbiologie I: Zelluläre Signaltransduktion, Martinistraße 52, 20246 Hamburg, Germany
| | - Stephen B. Shears
- *NIEHS/NIH, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, U.S.A
| | - Georg W. Mayr
- †Universitätsklinikum Hamburg-Eppendorf, Institut für Medizinische Biochemie und Molekularbiologie I: Zelluläre Signaltransduktion, Martinistraße 52, 20246 Hamburg, Germany
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Seeds AM, Frederick JP, Tsui MMK, York JD. Roles for inositol polyphosphate kinases in the regulation of nuclear processes and developmental biology. ACTA ACUST UNITED AC 2007; 47:10-25. [PMID: 17467778 PMCID: PMC3258027 DOI: 10.1016/j.advenzreg.2006.12.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
| | | | | | - John D. York
- To whom correspondence should be addressed: Department of Pharmacology and Cancer Biology, Howard Hughes Medical Institute, Duke University Medical Center, DUMC 3813, Durham, NC 27710, Tel: 919-681-6414, Fax: 919-668-0991, E-mail:
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Nalaskowski MM, Windhorst S, Stockebrand MC, Mayr GW. Subcellular localisation of human inositol 1,4,5-trisphosphate 3-kinase C: species-specific use of alternative export sites for nucleo-cytoplasmic shuttling indicates divergent roles of the catalytic and N-terminal domains. Biol Chem 2006; 387:583-93. [PMID: 16740130 DOI: 10.1515/bc.2006.075] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The three isoforms of human Ins(1,4,5)P3 3-kinase (IP3K) show remarkable differences in their intracellular targeting. Whereas predominant targeting to the cytoskeleton and endoplasmic reticulum has been shown for IP3K-A and IP3K-B, rat IP3K-C shuttles actively between the nucleus and cytoplasm. In the present study we examined the expression and intracellular localisation of endogenous IP3K-C in different mammalian cell lines using an isoform-specific antibody. In addition, human IP3K-C, showing remarkable differences to its rat homologue in the N-terminal targeting domain, was tagged with EGFP and used to examine active transport mechanisms into and out of the nucleus. We found both a nuclear import activity residing in its N-terminal domain and a nuclear export activity sensitive to treatment with leptomycin B. Different from the rat isoform, an exportin 1-dependent nuclear export site of the human enzyme resides outside the N-terminal targeting domain in the catalytic enzyme domain. A phylogenetic survey of vertebrate IP3K sequences indicates that in each of the three isoforms a nuclear export signal has evolved in the catalytic domain either de novo (IP3K-A) or as a substitute for an earlier evolved corresponding N-terminal signal (IP3K-B and IP3K-C). In higher vertebrates, and in particular in primates, re-export of nuclear IP3K activity may be guaranteed by the mechanism discovered.
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Affiliation(s)
- Marcus M Nalaskowski
- Institut für Biochemie und Molekularbiologie I: Zelluläre Signaltransduktion, Universitätsklinikum Hamburg-Eppendorf, Martinistr. 52, D-20246 Hamburg, Germany
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25
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York JD. Regulation of nuclear processes by inositol polyphosphates. Biochim Biophys Acta Mol Cell Biol Lipids 2006; 1761:552-9. [PMID: 16781889 DOI: 10.1016/j.bbalip.2006.04.014] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Accepted: 04/18/2006] [Indexed: 11/18/2022]
Abstract
Inositide signaling pathways represent a multifaceted ensemble of cellular switches capable of regulating a number of processes, for example, intracellular calcium release, membrane trafficking, chemotaxis, ion channel activity and several nuclear functions. Over 30 inositide messengers are found in eukaryotic cells that may be grouped into two classes: (1) inositol lipids, phosphatidylinositols or phosphoinositides (PIPs) and (2) water-soluble inositol polyphosphates (IPs). This review will focus on inositol polyphosphate kinases (IPK) and inositol pyrophosphate synthases (IPS) responsible for the cellular production of IP(4), IP(5) IP(6) and PP-IPs. Of interest, IPK and IPS proteins localize, in part, within the nucleus and their activities are necessary for proper regulation of gene expression, mRNA export, DNA repair and telomere maintenance. The breadth of nuclear processes regulated and the evolutionary conservation of the genes involved in their synthesis have sparked renewed interest in inositide messengers derived from sequential phosphorylation of inositol 1,4,5-trisphosphate.
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Affiliation(s)
- John D York
- Departments of Pharmacology and Cancer Biology and of Biochemistry, Howard Hughes Medical Institute, Duke University Medical Center, Box 3813, Durham, NC 27710, USA.
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26
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Chang SC, Majerus PW. Inositol polyphosphate multikinase regulates inositol 1,4,5,6-tetrakisphosphate. Biochem Biophys Res Commun 2006; 339:209-16. [PMID: 16293229 DOI: 10.1016/j.bbrc.2005.10.201] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2005] [Accepted: 10/31/2005] [Indexed: 01/31/2023]
Abstract
The human inositol phosphate multikinase (IPMK, 5-kinase) has a preferred 5-kinase activity over 3-kinase and 6-kinase activities and a substrate preference for inositol 1,3,4,6-tetrakisphosphate (Ins(1,3,4,6)P4) over inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) and inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4). We now report that the recombinant human protein can catalyze the conversion of inositol 1,4,5,6-tetrakisphosphate (Ins(1,4,5,6)P4) to Ins(1,3,4,5,6)P5 in vitro; the reaction product was identified by HPLC to be Ins(1,3,4,5,6)P5. The apparent Vmax was 42 nmol of Ins(1,3,4,5,6)P5 formed/min/mg protein, and the apparent Km was 222 nM using Ins(1,3,4,6)P4 as a substrate; the catalytic efficiency was similar to that for Ins(1,4,5)P3. Stable over-expression of the human protein in HEK-293 cells abrogates the in vivo elevation of Ins(1,4,5,6)P4 from the Salmonella dublin SopB protein. Hence, the human 5-kinase may also regulate the level of Ins(1,4,5,6)P4 and have an effect on chloride channel regulation.
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Affiliation(s)
- Shao-Chun Chang
- Department of Internal Medicine, Division of Hematology, Box 8125, Washington University, School of Medicine, St. Louis, MO 63110, USA
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Ungewickell A, Hugge C, Kisseleva M, Chang SC, Zou J, Feng Y, Galyov EE, Wilson M, Majerus PW. The identification and characterization of two phosphatidylinositol-4,5-bisphosphate 4-phosphatases. Proc Natl Acad Sci U S A 2005; 102:18854-9. [PMID: 16365287 PMCID: PMC1323219 DOI: 10.1073/pnas.0509740102] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Numerous inositol polyphosphate 5-phosphatases catalyze the degradation of phosphatidylinositol-4,5-bisphosphate (PtdIns-4,5-P(2)) to phosphatidylinositol-4-phosphate (PtdIns-4-P). An alternative pathway to degrade PtdIns-4,5-P(2) is the hydrolysis of PtdIns-4,5-P(2) by a 4-phosphatase, leading to the production of PtdIns-5-P. Whereas the bacterial IpgD enzyme is known to catalyze this reaction, no such mammalian enzyme has been found. We have identified and characterized two previously undescribed human enzymes, PtdIns-4,5-P(2) 4-phosphatase type I and type II, which catalyze the hydrolysis of PtdIns-4,5-P(2) to phosphatidylinositol-5-phosphate (PtdIns-5-P). Both enzymes are ubiquitously expressed and localize to late endosomal/lysosomal membranes in epithelial cells. Overexpression of either enzyme in HeLa cells increases EGF-receptor degradation upon EGF stimulation.
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Affiliation(s)
- Alexander Ungewickell
- Division of Hematology, Washington University School of Medicine, St. Louis, MO 63110, USA
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