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Elbatsh AMO, Amin-Mansour A, Haberkorn A, Textor C, Ebel N, Renard E, Koch LM, Groenveld FC, Piquet M, Naumann U, Ruddy DA, Romanet V, Martínez Gómez JM, Shirley MD, Wipfli P, Schnell C, Wartmann M, Rausch M, Jager MJ, Levesque MP, Maira SM, Manchado E. INPP5A phosphatase is a synthetic lethal target in GNAQ and GNA11-mutant melanomas. NATURE CANCER 2024; 5:481-499. [PMID: 38233483 DOI: 10.1038/s43018-023-00710-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 12/14/2023] [Indexed: 01/19/2024]
Abstract
Activating mutations in GNAQ/GNA11 occur in over 90% of uveal melanomas (UMs), the most lethal melanoma subtype; however, targeting these oncogenes has proven challenging and inhibiting their downstream effectors show limited clinical efficacy. Here, we performed genome-scale CRISPR screens along with computational analyses of cancer dependency and gene expression datasets to identify the inositol-metabolizing phosphatase INPP5A as a selective dependency in GNAQ/11-mutant UM cells in vitro and in vivo. Mutant cells intrinsically produce high levels of the second messenger inositol 1,4,5 trisphosphate (IP3) that accumulate upon suppression of INPP5A, resulting in hyperactivation of IP3-receptor signaling, increased cytosolic calcium and p53-dependent apoptosis. Finally, we show that GNAQ/11-mutant UM cells and patients' tumors exhibit elevated levels of IP4, a biomarker of enhanced IP3 production; these high levels are abolished by GNAQ/11 inhibition and correlate with sensitivity to INPP5A depletion. Our findings uncover INPP5A as a synthetic lethal vulnerability and a potential therapeutic target for GNAQ/11-mutant-driven cancers.
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Affiliation(s)
- Ahmed M O Elbatsh
- Oncology, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Ali Amin-Mansour
- Oncology, Novartis Institute for Biomedical Research, Cambridge, MA, USA
| | - Anne Haberkorn
- Oncology, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Claudia Textor
- PK Sciences, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Nicolas Ebel
- Oncology, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Emilie Renard
- Oncology, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Lisa M Koch
- Oncology, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Femke C Groenveld
- Oncology, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Michelle Piquet
- Oncology, Novartis Institute for Biomedical Research, Cambridge, MA, USA
| | - Ulrike Naumann
- Chemical Biology and Therapeutics, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - David A Ruddy
- Oncology, Novartis Institute for Biomedical Research, Cambridge, MA, USA
| | - Vincent Romanet
- Oncology, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Julia M Martínez Gómez
- Dermatology Department, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Matthew D Shirley
- Oncology, Novartis Institute for Biomedical Research, Cambridge, MA, USA
| | - Peter Wipfli
- PK Sciences, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Christian Schnell
- Oncology, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Markus Wartmann
- Oncology, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Martin Rausch
- Chemical Biology and Therapeutics, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Martine J Jager
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands
| | - Mitchell P Levesque
- Dermatology Department, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | | | - Eusebio Manchado
- Oncology, Novartis Institute for Biomedical Research, Basel, Switzerland.
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2
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Wang Z, Wu P, Shi J, Ji X, He L, Dong W, Wang Z, Zhang H, Sun W. A novel necroptosis-related gene signature associated with immune landscape for predicting the prognosis of papillary thyroid cancer. Front Genet 2022; 13:947216. [PMID: 36186479 PMCID: PMC9520455 DOI: 10.3389/fgene.2022.947216] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 08/24/2022] [Indexed: 11/29/2022] Open
Abstract
Background: Necroptosis, a type of programmed cell death, has been implicated in a variety of cancer-related biological processes. However, the roles of necroptosis-related genes in thyroid cancer yet remain unknown. Methods: A necroptosis-related gene signature was constructed using the least absolute shrinkage and selection operator (LASSO) regression analysis and Cox regression analysis. The predictive value of the prognostic signature was validated in an internal cohort. Additionally, the single-sample gene set enrichment analysis (ssGSEA) was used to examine the relationships between necroptosis and immune cells, immunological functions, and immune checkpoints. Next, the modeled genes expressions were validated in 96 pairs of clinical tumor and normal tissue samples. Finally, the effects of modeled genes on PTC cells were studied by RNA interference approaches in vitro. Results: In this study, the risk signature of seven necroptosis-related genes was created to predict the prognosis of papillary thyroid cancer (PTC) patients, and all patients were divided into high- and low-risk groups. Patients in the high-risk group fared worse in terms of overall survival than those in the low-risk group. The area under the curve (AUC) of the receiving operating characteristic (ROC) curves proved the predictive capability of created signature. The risk score was found to be an independent risk factor for prognosis in multivariate Cox analysis. The low-risk group showed increased immune cell infiltration and immunological activity, implying that they might respond better to immune checkpoint inhibitor medication. Next, GEO database and qRT-PCR in 96 pairs of matched tumorous and non-tumorous tissues were used to validate the expression of the seven modeled genes in PTCs, and the results were compatible with TCGA database. Finally, overexpression of IPMK, KLF9, SPATA2 could significantly inhibit the proliferation, invasion and migration of PTC cells. Conclusion: The created necroptosis associated risk signature has the potential to have prognostic capability in PTC for patient outcome. The findings of this study could pave the way for further research into the link between necroptosis and tumor immunotherapy.
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Affiliation(s)
| | | | | | | | | | | | | | - Hao Zhang
- *Correspondence: Wei Sun, ; Hao Zhang,
| | - Wei Sun
- *Correspondence: Wei Sun, ; Hao Zhang,
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3
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Metabolic supervision by PPIP5K, an inositol pyrophosphate kinase/phosphatase, controls proliferation of the HCT116 tumor cell line. Proc Natl Acad Sci U S A 2021; 118:2020187118. [PMID: 33649228 PMCID: PMC7958180 DOI: 10.1073/pnas.2020187118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Identification of common patterns of cancer metabolic reprogramming could assist the development of new therapeutic strategies. Recent attention in this field has focused on identifying and targeting signal transduction pathways that interface directly with major metabolic control processes. In the current study we demonstrate the importance of signaling by the diphosphoinositol pentakisphosphate kinases (PPIP5Ks) to the metabolism and proliferation of the HCT116 colonic tumor cell line. We observed reciprocal cross talk between PPIP5K catalytic activity and glucose metabolism, and we show that CRISPR-mediated PPIP5K deletion suppresses HCT116 cell proliferation in glucose-limited culture conditions that mimic the tumor cell microenvironment. We conducted detailed, global metabolomic analyses of wild-type and PPIP5K knockout (KO) cells by measuring both steady-state metabolite levels and by performing isotope tracing experiments. We attribute the growth-impaired phenotype to a specific reduction in the supply of precursor material for de novo nucleotide biosynthesis from the one carbon serine/glycine pathway and the pentose phosphate pathway. We identify two enzymatic control points that are inhibited in the PPIP5K KO cells: serine hydroxymethyltransferase and phosphoribosyl pyrophosphate synthetase, a known downstream target of AMP-regulated protein kinase, which we show is noncanonically activated independently of adenine nucleotide status. Finally, we show the proliferative defect in PPIP5K KO cells can be significantly rescued either by addition of inosine monophosphate or a nucleoside mixture or by stable expression of PPIP5K activity. Overall, our data describe multiple, far-reaching metabolic consequences for metabolic supervision by PPIP5Ks in a tumor cell line.
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4
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Lete MG, Tripathi A, Chandran V, Bankaitis VA, McDermott MI. Lipid transfer proteins and instructive regulation of lipid kinase activities: Implications for inositol lipid signaling and disease. Adv Biol Regul 2020; 78:100740. [PMID: 32992233 PMCID: PMC7986245 DOI: 10.1016/j.jbior.2020.100740] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/16/2020] [Accepted: 06/24/2020] [Indexed: 05/17/2023]
Abstract
Cellular membranes are critical platforms for intracellular signaling that involve complex interfaces between lipids and proteins, and a web of interactions between a multitude of lipid metabolic pathways. Membrane lipids impart structural and functional information in this regulatory circuit that encompass biophysical parameters such as membrane thickness and fluidity, as well as chaperoning the interactions of protein binding partners. Phosphatidylinositol and its phosphorylated derivatives, the phosphoinositides, play key roles in intracellular membrane signaling, and these involvements are translated into an impressively diverse set of biological outcomes. The phosphatidylinositol transfer proteins (PITPs) are key regulators of phosphoinositide signaling. Found in a diverse array of organisms from plants, yeast and apicomplexan parasites to mammals, PITPs were initially proposed to be simple transporters of lipids between intracellular membranes. It now appears increasingly unlikely that the soluble versions of these proteins perform such functions within the cell. Rather, these serve to facilitate the activity of intrinsically biologically insufficient inositol lipid kinases and, in so doing, promote diversification of the biological outcomes of phosphoinositide signaling. The central engine for execution of such functions is the lipid exchange cycle that is a fundamental property of PITPs. How PITPs execute lipid exchange remains very poorly understood. Molecular dynamics simulation approaches are now providing the first atomistic insights into how PITPs, and potentially other lipid-exchange/transfer proteins, operate.
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Affiliation(s)
- Marta G Lete
- Department of Molecular and Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX, 77843-1114, USA; Institute Biofisika (UPV/EHU, CSIC) and University of the Basque Country, Leioa, Spain
| | - Ashutosh Tripathi
- Department of Molecular and Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX, 77843-1114, USA
| | - Vijay Chandran
- Department of Molecular and Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX, 77843-1114, USA
| | - Vytas A Bankaitis
- Department of Molecular and Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX, 77843-1114, USA; Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843-2128, USA; Department of Chemistry, Texas A&M University, College Station, TX, 77840, USA
| | - Mark I McDermott
- Department of Molecular and Cellular Medicine, Texas A&M Health Sciences Center, College Station, TX, 77843-1114, USA.
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5
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Ucuncu E, Rajamani K, Wilson MSC, Medina-Cano D, Altin N, David P, Barcia G, Lefort N, Banal C, Vasilache-Dangles MT, Pitelet G, Lorino E, Rabasse N, Bieth E, Zaki MS, Topcu M, Sonmez FM, Musaev D, Stanley V, Bole-Feysot C, Nitschké P, Munnich A, Bahi-Buisson N, Fossoud C, Giuliano F, Colleaux L, Burglen L, Gleeson JG, Boddaert N, Saiardi A, Cantagrel V. MINPP1 prevents intracellular accumulation of the chelator inositol hexakisphosphate and is mutated in Pontocerebellar Hypoplasia. Nat Commun 2020; 11:6087. [PMID: 33257696 PMCID: PMC7705663 DOI: 10.1038/s41467-020-19919-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Accepted: 10/29/2020] [Indexed: 12/13/2022] Open
Abstract
Inositol polyphosphates are vital metabolic and secondary messengers, involved in diverse cellular functions. Therefore, tight regulation of inositol polyphosphate metabolism is essential for proper cell physiology. Here, we describe an early-onset neurodegenerative syndrome caused by loss-of-function mutations in the multiple inositol-polyphosphate phosphatase 1 gene (MINPP1). Patients are found to have a distinct type of Pontocerebellar Hypoplasia with typical basal ganglia involvement on neuroimaging. We find that patient-derived and genome edited MINPP1−/− induced stem cells exhibit an inefficient neuronal differentiation combined with an increased cell death. MINPP1 deficiency results in an intracellular imbalance of the inositol polyphosphate metabolism. This metabolic defect is characterized by an accumulation of highly phosphorylated inositols, mostly inositol hexakisphosphate (IP6), detected in HEK293 cells, fibroblasts, iPSCs and differentiating neurons lacking MINPP1. In mutant cells, higher IP6 level is expected to be associated with an increased chelation of intracellular cations, such as iron or calcium, resulting in decreased levels of available ions. These data suggest the involvement of IP6-mediated chelation on Pontocerebellar Hypoplasia disease pathology and thereby highlight the critical role of MINPP1 in the regulation of human brain development and homeostasis. Tight regulation of inositol polyphosphate metabolism is essential for proper cell physiology. Here, the authors describe an early-onset neurodegenerative syndrome caused by loss-of-function mutations in the MINPP1 gene, characterised by intracellular imbalance of inositol polyphosphate metabolism.
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Affiliation(s)
- Ekin Ucuncu
- Université de Paris, Developmental Brain Disorders Laboratory, Imagine Institute, INSERM UMR 1163, F-75015, Paris, France
| | - Karthyayani Rajamani
- Université de Paris, Developmental Brain Disorders Laboratory, Imagine Institute, INSERM UMR 1163, F-75015, Paris, France
| | - Miranda S C Wilson
- MRC Laboratory for Molecular Cell Biology, University College London, WC1E 6BT, London, UK
| | - Daniel Medina-Cano
- Université de Paris, Developmental Brain Disorders Laboratory, Imagine Institute, INSERM UMR 1163, F-75015, Paris, France
| | - Nami Altin
- Université de Paris, Developmental Brain Disorders Laboratory, Imagine Institute, INSERM UMR 1163, F-75015, Paris, France
| | - Pierre David
- Transgenesis Platform, Laboratoire d'Expérimentation Animale et Transgenèse (LEAT), Imagine Institute, Structure Fédérative de Recherche Necker INSERM US24/CNRS UMS3633, 75015, Paris, France
| | - Giulia Barcia
- Université de Paris, Developmental Brain Disorders Laboratory, Imagine Institute, INSERM UMR 1163, F-75015, Paris, France.,Département de Génétique Médicale, AP-HP, Hôpital Necker-Enfants Malades, F-75015, Paris, France
| | - Nathalie Lefort
- Université de Paris, iPSC Core Facility, Imagine Institute, INSERM UMR 1163, F-75015, Paris, France
| | - Céline Banal
- Université de Paris, iPSC Core Facility, Imagine Institute, INSERM UMR 1163, F-75015, Paris, France
| | | | - Gaële Pitelet
- Service de Neuropédiatrie, CHU Nice, 06200, Nice, France
| | - Elsa Lorino
- ESEAN, 44200 Nantes, Service de maladies chroniques de l'enfant, CHU Nantes, 44093, Nantes, France
| | - Nathalie Rabasse
- Service de pédiatrie, hôpital d'Antibes-Juan-les-Pins, 06600, Antibes-Juan-les-Pins, France
| | - Eric Bieth
- Service de Génétique Médicale, CHU Toulouse, 31059, Toulouse, France
| | - Maha S Zaki
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, 12311, Egypt
| | - Meral Topcu
- Department of Child Neurology, Faculty of Medicine, Hacettepe University, Ankara, 06100, Turkey
| | - Fatma Mujgan Sonmez
- Guven Hospital, Child Neurology Department, Ankara, Turkey.,Department of Child Neurology, Faculty of Medicine, Karadeniz Technical University, Trabzon, 61080, Turkey
| | - Damir Musaev
- Laboratory for Pediatric Brain Diseases, Rady Children's Institute for Genomic Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Valentina Stanley
- Laboratory for Pediatric Brain Diseases, Rady Children's Institute for Genomic Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Christine Bole-Feysot
- Université de Paris, Genomics Platform, Imagine Institute, INSERM UMR 1163, F-75015, Paris, France
| | - Patrick Nitschké
- Université de Paris, Bioinformatics Core Facility, Imagine Institute, INSERM UMR 1163, F-75015, Paris, France
| | - Arnold Munnich
- Université de Paris, Translational Genetics Laboratory, Imagine Institute, INSERM UMR 1163, F-75015, Paris, France
| | - Nadia Bahi-Buisson
- Université de Paris, Genetics and Development of the Cerebral Cortex Laboratory, Imagine Institute, INSERM UMR 1163, F-75015, Paris, France
| | - Catherine Fossoud
- Centre de Référence des Troubles des Apprentissages, Hôpitaux Pédiatriques de Nice CHU-Lenval, 06200, Nice, France
| | - Fabienne Giuliano
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nice, 06202, Nice, France
| | - Laurence Colleaux
- Université de Paris, Developmental Brain Disorders Laboratory, Imagine Institute, INSERM UMR 1163, F-75015, Paris, France
| | - Lydie Burglen
- Université de Paris, Developmental Brain Disorders Laboratory, Imagine Institute, INSERM UMR 1163, F-75015, Paris, France.,Centre de Référence des Malformations et Maladies Congénitales du Cervelet, Département de Génétique, AP-HP, Sorbonne Université, Hôpital Trousseau, 75012, Paris, France
| | - Joseph G Gleeson
- Laboratory for Pediatric Brain Diseases, Rady Children's Institute for Genomic Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Nathalie Boddaert
- Département de radiologie pédiatrique, INSERM UMR 1163 and INSERM U1000, AP-HP, Hôpital Necker-Enfants Malades, F-75015, Paris, France
| | - Adolfo Saiardi
- MRC Laboratory for Molecular Cell Biology, University College London, WC1E 6BT, London, UK.
| | - Vincent Cantagrel
- Université de Paris, Developmental Brain Disorders Laboratory, Imagine Institute, INSERM UMR 1163, F-75015, Paris, France.
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6
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Minini M, Senni A, Unfer V, Bizzarri M. The Key Role of IP 6K: A Novel Target for Anticancer Treatments? Molecules 2020; 25:molecules25194401. [PMID: 32992691 PMCID: PMC7583815 DOI: 10.3390/molecules25194401] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 09/20/2020] [Accepted: 09/21/2020] [Indexed: 12/29/2022] Open
Abstract
Inositol and its phosphate metabolites play a pivotal role in several biochemical pathways and gene expression regulation: inositol pyrophosphates (PP-IPs) have been increasingly appreciated as key signaling modulators. Fluctuations in their intracellular levels hugely impact the transfer of phosphates and the phosphorylation status of several target proteins. Pharmacological modulation of the proteins associated with PP-IP activities has proved to be beneficial in various pathological settings. IP7 has been extensively studied and found to play a key role in pathways associated with PP-IP activities. Three inositol hexakisphosphate kinase (IP6K) isoforms regulate IP7 synthesis in mammals. Genomic deletion or enzymic inhibition of IP6K1 has been shown to reduce cell invasiveness and migration capacity, protecting against chemical-induced carcinogenesis. IP6K1 could therefore be a useful target in anticancer treatment. Here, we summarize the current understanding that established IP6K1 and the other IP6K isoforms as possible targets for cancer therapy. However, it will be necessary to determine whether pharmacological inhibition of IP6K is safe enough to begin clinical study. The development of safe and selective inhibitors of IP6K isoforms is required to minimize undesirable effects.
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Affiliation(s)
- Mirko Minini
- Department of Experimental Medicine, Sapienza University of Rome, 00161 Rome, Italy;
- Department of Surgery ‘P. Valdoni’, Sapienza University of Rome, 00161 Rome, Italy
- Systems Biology Group Lab, Sapienza University of Rome, 00185 Rome, Italy;
- Correspondence: (M.M.); (M.B.)
| | - Alice Senni
- Department of Experimental Medicine, Sapienza University of Rome, 00161 Rome, Italy;
- Department of Surgery ‘P. Valdoni’, Sapienza University of Rome, 00161 Rome, Italy
| | - Vittorio Unfer
- Systems Biology Group Lab, Sapienza University of Rome, 00185 Rome, Italy;
| | - Mariano Bizzarri
- Department of Experimental Medicine, Sapienza University of Rome, 00161 Rome, Italy;
- Systems Biology Group Lab, Sapienza University of Rome, 00185 Rome, Italy;
- Correspondence: (M.M.); (M.B.)
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7
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InsP 7 is a small-molecule regulator of NUDT3-mediated mRNA decapping and processing-body dynamics. Proc Natl Acad Sci U S A 2020; 117:19245-19253. [PMID: 32727897 DOI: 10.1073/pnas.1922284117] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Regulation of enzymatic 5' decapping of messenger RNA (mRNA), which normally commits transcripts to their destruction, has the capacity to dynamically reshape the transcriptome. For example, protection from 5' decapping promotes accumulation of mRNAs into processing (P) bodies-membraneless, biomolecular condensates. Such compartmentalization of mRNAs temporarily removes them from the translatable pool; these repressed transcripts are stabilized and stored until P-body dissolution permits transcript reentry into the cytosol. Here, we describe regulation of mRNA stability and P-body dynamics by the inositol pyrophosphate signaling molecule 5-InsP7 (5-diphosphoinositol pentakisphosphate). First, we demonstrate 5-InsP7 inhibits decapping by recombinant NUDT3 (Nudix [nucleoside diphosphate linked moiety X]-type hydrolase 3) in vitro. Next, in intact HEK293 and HCT116 cells, we monitored the stability of a cadre of NUDT3 mRNA substrates following CRISPR-Cas9 knockout of PPIP5Ks (diphosphoinositol pentakisphosphate 5-kinases type 1 and 2, i.e., PPIP5K KO), which elevates cellular 5-InsP7 levels by two- to threefold (i.e., within the physiological rheostatic range). The PPIP5K KO cells exhibited elevated levels of NUDT3 mRNA substrates and increased P-body abundance. Pharmacological and genetic attenuation of 5-InsP7 synthesis in the KO background reverted both NUDT3 mRNA substrate levels and P-body counts to those of wild-type cells. Furthermore, liposomal delivery of a metabolically resistant 5-InsP7 analog into wild-type cells elevated levels of NUDT3 mRNA substrates and raised P-body abundance. In the context that cellular 5-InsP7 levels normally fluctuate in response to changes in the bioenergetic environment, regulation of mRNA structure by this inositol pyrophosphate represents an epitranscriptomic control process. The associated impact on P-body dynamics has relevance to regulation of stem cell differentiation, stress responses, and, potentially, amelioration of neurodegenerative diseases and aging.
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8
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Vip1 is a kinase and pyrophosphatase switch that regulates inositol diphosphate signaling. Proc Natl Acad Sci U S A 2020; 117:9356-9364. [PMID: 32303658 PMCID: PMC7196807 DOI: 10.1073/pnas.1908875117] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Inositol diphosphates (PP-IPs), also known as inositol pyrophosphates, are high-energy cellular signaling codes involved in nutrient and regulatory responses. We report that the evolutionarily conserved gene product, Vip1, possesses autonomous kinase and pyrophosphatase domains capable of synthesis and destruction of D-1 PP-IPs. Our studies provide atomic-resolution structures of the PP-IP products and unequivocally define that the Vip1 gene product is a highly selective 1-kinase and 1-pyrophosphatase enzyme whose activities arise through distinct active sites. Kinetic analyses of kinase and pyrophosphatase parameters are consistent with Vip1 evolving to modulate levels of 1-IP7 and 1,5-IP8 Individual perturbations in kinase and pyrophosphatase activities in cells result in differential effects on vacuolar morphology and osmotic responses. Analogous to the dual-functional key energy metabolism regulator, phosphofructokinase 2, Vip1 is a kinase and pyrophosphatase switch whose 1-PP-IP products play an important role in a cellular adaptation.
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9
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Metabolic Labeling of Inositol Phosphates and Phosphatidylinositols in Yeast and Mammalian Cells. Methods Mol Biol 2020; 2091:83-92. [PMID: 31773572 DOI: 10.1007/978-1-0716-0167-9_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Inositol phosphate (IP) and phosphatidylinositol (PI) signaling are critical signal transduction pathways responsible for generating numerous receptor-mediated cellular responses. Biochemical and genetic studies have revealed diverse roles of IP and PI signaling in eukaryotic signaling, but detailed characterization of unique IP and PI signaling profiles in response to different agonists and among cell types remains largely unexplored. Here, we outline steady-state inositol metabolic-labeling techniques that can be leveraged to assess the IP and PI signaling state in eukaryotic cells. This flexible technique can be amended and optimized to your cell line of interest, perturbed with biochemical, genetic, or pharmacological alteration, and used to provide comprehensive inositol profiling in various cellular systems.
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10
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ITPK1 mediates the lipid-independent synthesis of inositol phosphates controlled by metabolism. Proc Natl Acad Sci U S A 2019; 116:24551-24561. [PMID: 31754032 PMCID: PMC6900528 DOI: 10.1073/pnas.1911431116] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Inositol phosphates (IPs) are a class of signaling molecules regulating cell physiology. The best-characterized IP, the calcium release factor IP3, is generated by phospholipase C hydrolysis of phosphoinositides lipids. For historical and technical reasons, IPs synthesis is believed to originate from the lipid-generated IP3. While this is true in yeast, our work has demonstrated that other organisms use a “soluble” (nonlipid) route to synthesize IPs. This soluble pathway depends on the metabolic status of the cells, and is under the control of the kinase ITPK1, which phosphorylates inositol monophosphate likely generated from glucose. The data shed light on the evolutionary origin of IPs, signaling and tightening the link between these small molecules and basic metabolism. Inositol phosphates (IPs) comprise a network of phosphorylated molecules that play multiple signaling roles in eukaryotes. IPs synthesis is believed to originate with IP3 generated from PIP2 by phospholipase C (PLC). Here, we report that in mammalian cells PLC-generated IPs are rapidly recycled to inositol, and uncover the enzymology behind an alternative “soluble” route to synthesis of IPs. Inositol tetrakisphosphate 1-kinase 1 (ITPK1)—found in Asgard archaea, social amoeba, plants, and animals—phosphorylates I(3)P1 originating from glucose-6-phosphate, and I(1)P1 generated from sphingolipids, to enable synthesis of IP6. We also found using PAGE mass assay that metabolic blockage by phosphate starvation surprisingly increased IP6 levels in a ITPK1-dependent manner, establishing a route to IP6 controlled by cellular metabolic status, that is not detectable by traditional [3H]-inositol labeling. The presence of ITPK1 in archaeal clades thought to define eukaryogenesis indicates that IPs had functional roles before the appearance of the eukaryote.
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11
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Clarke BP, Logeman BL, Hale AT, Luka Z, York JD. A synthetic biological approach to reconstitution of inositide signaling pathways in bacteria. Adv Biol Regul 2019; 73:100637. [PMID: 31378699 DOI: 10.1016/j.jbior.2019.100637] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/01/2019] [Accepted: 07/04/2019] [Indexed: 11/19/2022]
Abstract
Inositide lipid (PIP) and soluble (IP) signaling pathways produce essential cellular codes conserved in eukaryotes. In many cases, deconvoluting metabolic and functional aspects of individual pathways are confounded by promiscuity and multiplicity of PIP and IP kinases and phosphatases. We report a molecular genetic approach that reconstitutes eukaryotic inositide lipid and soluble pathways in a prokaryotic cell which inherently lack inositide kinases and phosphatases in their genome. By expressing synthetic cassettes of eukaryotic genes, we have reconstructed the heterologous formation of a range of inositide lipids, including PI(3)P, PI(4,5)P2 and PIP3. In addition, we report the reconstruction of lipid-dependent production of inositol hexakisphosphate (IP6). Our synthetic system is scalable, reduces confounding metabolic issues, for example it is devoid of inositide phosphatases and orthologous kinases, and enables accurate characterization gene product enzymatic activity and substrate selectivity. This genetically engineered tool is designed to help interpret metabolic pathways and may facilitate in vivo testing of regulators and small molecule inhibitors. In summary, heterologous expression of inositide pathways in bacteria provide a malleable experimental platform for aiding signaling biologists and offers new insights into metabolism of these essential pathways.
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Affiliation(s)
- Bradley P Clarke
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Brandon L Logeman
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, USA
| | - Andrew T Hale
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Zigmund Luka
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - John D York
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA; Department of Pharmacology and Cancer Biology, Duke University, Durham, NC, USA.
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12
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McNamara DE, Dovey CM, Hale AT, Quarato G, Grace CR, Guibao CD, Diep J, Nourse A, Cai CR, Wu H, Kalathur RC, Green DR, York JD, Carette JE, Moldoveanu T. Direct Activation of Human MLKL by a Select Repertoire of Inositol Phosphate Metabolites. Cell Chem Biol 2019; 26:863-877.e7. [PMID: 31031142 DOI: 10.1016/j.chembiol.2019.03.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 02/08/2019] [Accepted: 03/15/2019] [Indexed: 12/29/2022]
Abstract
Necroptosis is an inflammatory form of programmed cell death executed through plasma membrane rupture by the pseudokinase mixed lineage kinase domain-like (MLKL). We previously showed that MLKL activation requires metabolites of the inositol phosphate (IP) pathway. Here we reveal that I(1,3,4,6)P4, I(1,3,4,5,6)P5, and IP6 promote membrane permeabilization by MLKL through directly binding the N-terminal executioner domain (NED) and dissociating its auto-inhibitory region. We show that IP6 and inositol pentakisphosphate 2-kinase (IPPK) are required for necroptosis as IPPK deletion ablated IP6 production and inhibited necroptosis. The NED auto-inhibitory region is more extensive than originally described and single amino acid substitutions along this region induce spontaneous necroptosis by MLKL. Activating IPs bind three sites with affinity of 100-600 μM to destabilize contacts between the auto-inhibitory region and NED, thereby promoting MLKL activation. We therefore uncover MLKL's activating switch in NED triggered by a select repertoire of IP metabolites.
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Affiliation(s)
- Dan E McNamara
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Cole M Dovey
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Andrew T Hale
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Giovanni Quarato
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Christy R Grace
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Cristina D Guibao
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Jonathan Diep
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Amanda Nourse
- Molecular Interaction Analysis Shared Resource, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Casey R Cai
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Hong Wu
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Ravi C Kalathur
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Douglas R Green
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - John D York
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Jan E Carette
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Tudor Moldoveanu
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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13
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Dovey CM, Diep J, Clarke BP, Hale AT, McNamara DE, Guo H, Brown NW, Cao JY, Grace CR, Gough PJ, Bertin J, Dixon SJ, Fiedler D, Mocarski ES, Kaiser WJ, Moldoveanu T, York JD, Carette JE. MLKL Requires the Inositol Phosphate Code to Execute Necroptosis. Mol Cell 2018; 70:936-948.e7. [PMID: 29883610 PMCID: PMC5994928 DOI: 10.1016/j.molcel.2018.05.010] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 02/12/2018] [Accepted: 05/07/2018] [Indexed: 01/28/2023]
Abstract
Necroptosis is an important form of lytic cell death triggered by injury and infection, but whether mixed lineage kinase domain-like (MLKL) is sufficient to execute this pathway is unknown. In a genetic selection for human cell mutants defective for MLKL-dependent necroptosis, we identified mutations in IPMK and ITPK1, which encode inositol phosphate (IP) kinases that regulate the IP code of soluble molecules. We show that IP kinases are essential for necroptosis triggered by death receptor activation, herpesvirus infection, or a pro-necrotic MLKL mutant. In IP kinase mutant cells, MLKL failed to oligomerize and localize to membranes despite proper receptor-interacting protein kinase-3 (RIPK3)-dependent phosphorylation. We demonstrate that necroptosis requires IP-specific kinase activity and that a highly phosphorylated product, but not a lowly phosphorylated precursor, potently displaces the MLKL auto-inhibitory brace region. These observations reveal control of MLKL-mediated necroptosis by a metabolite and identify a key molecular mechanism underlying regulated cell death.
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Affiliation(s)
- Cole M Dovey
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Jonathan Diep
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Bradley P Clarke
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Andrew T Hale
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Dan E McNamara
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Hongyan Guo
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health Sciences Center, San Antonio, TX 78229, USA
| | - Nathaniel W Brown
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA; Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
| | | | - Christy R Grace
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Peter J Gough
- Host Defense Discovery Performance Unit, Infectious Diseases Therapy Area Unit, GlaxoSmithKline, Collegeville, PA 19426, USA
| | - John Bertin
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Collegeville, PA 19426, USA
| | - Scott J Dixon
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Dorothea Fiedler
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany
| | - Edward S Mocarski
- Department of Microbiology and Immunology, Emory Vaccine Center, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - William J Kaiser
- Department of Microbiology, Immunology and Molecular Genetics, University of Texas Health Sciences Center, San Antonio, TX 78229, USA
| | - Tudor Moldoveanu
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - John D York
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Jan E Carette
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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14
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Hatch AJ, Odom AR, York JD. Inositol phosphate multikinase dependent transcriptional control. Adv Biol Regul 2017; 64:9-19. [PMID: 28342784 PMCID: PMC6198329 DOI: 10.1016/j.jbior.2017.03.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 03/13/2017] [Accepted: 03/14/2017] [Indexed: 10/19/2022]
Abstract
Production of lipid-derived inositol phosphates including IP4 and IP5 is an evolutionarily conserved process essential for cellular adaptive responses that is dependent on both phospholipase C and the inositol phosphate multikinase Ipk2 (also known as Arg82 and IPMK). Studies of Ipk2, along with Arg82 prior to demonstrating its IP kinase activity, have provided an important link between control of gene expression and IP metabolism as both kinase dependent and independent functions are required for proper transcriptional complex function that enables cellular adaptation in response to extracellular queues such as nutrient availability. Here we define a promoter sequence cis-element, 5'-CCCTAAAAGG-3', that mediates both kinase-dependent and independent functions of Ipk2. Using a synthetic biological strategy, we show that proper gene expression in cells lacking Ipk2 may be restored through add-back of two components: IP4/IP5 production and overproduction of the MADS box DNA binding protein, Mcm1. Our results are consistent with a mechanism by which Ipk2 harbors a dual functionality that stabilizes transcription factor levels and enzymatically produces a small molecule code, which together coordinate control of biological processes and gene expression.
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Affiliation(s)
- Ace J Hatch
- Departments of Pharmacology and Cancer Biology and of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - Audrey R Odom
- Departments of Pharmacology and Cancer Biology and of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - John D York
- Departments of Pharmacology and Cancer Biology and of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA; Department of Biochemistry, Vanderbilt University, 607 Light Hall, Nashville, TN 37232-0146, USA.
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15
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Gu C, Nguyen HN, Hofer A, Jessen HJ, Dai X, Wang H, Shears SB. The Significance of the Bifunctional Kinase/Phosphatase Activities of Diphosphoinositol Pentakisphosphate Kinases (PPIP5Ks) for Coupling Inositol Pyrophosphate Cell Signaling to Cellular Phosphate Homeostasis. J Biol Chem 2017; 292:4544-4555. [PMID: 28126903 PMCID: PMC5377771 DOI: 10.1074/jbc.m116.765743] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 01/25/2017] [Indexed: 12/31/2022] Open
Abstract
Proteins responsible for Pi homeostasis are critical for all life. In Saccharomyces cerevisiae, extracellular [Pi] is "sensed" by the inositol-hexakisphosphate kinase (IP6K) that synthesizes the intracellular inositol pyrophosphate 5-diphosphoinositol 1,2,3,4,6-pentakisphosphate (5-InsP7) as follows: during a period of Pi starvation, there is a decline in cellular [ATP]; the unusually low affinity of IP6Ks for ATP compels 5-InsP7 levels to fall in parallel (Azevedo, C., and Saiardi, A. (2017) Trends. Biochem. Sci. 42, 219-231. Hitherto, such Pi sensing has not been documented in metazoans. Here, using a human intestinal epithelial cell line (HCT116), we show that levels of both 5-InsP7 and ATP decrease upon [Pi] starvation and subsequently recover during Pi replenishment. However, a separate inositol pyrophosphate, 1,5-bisdiphosphoinositol 2,3,4,6-tetrakisphosphate (InsP8), reacts more dramatically (i.e. with a wider dynamic range and greater sensitivity). To understand this novel InsP8 response, we characterized kinetic properties of the bifunctional 5-InsP7 kinase/InsP8 phosphatase activities of full-length diphosphoinositol pentakisphosphate kinases (PPIP5Ks). These data fulfil previously published criteria for any bifunctional kinase/phosphatase to exhibit concentration robustness, permitting levels of the kinase product (InsP8 in this case) to fluctuate independently of varying precursor (i.e. 5-InsP7) pool size. Moreover, we report that InsP8 phosphatase activities of PPIP5Ks are strongly inhibited by Pi (40-90% within the 0-1 mm range). For PPIP5K2, Pi sensing by InsP8 is amplified by a 2-fold activation of 5-InsP7 kinase activity by Pi within the 0-5 mm range. Overall, our data reveal mechanisms that can contribute to specificity in inositol pyrophosphate signaling, regulating InsP8 turnover independently of 5-InsP7, in response to fluctuations in extracellular supply of a key nutrient.
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Affiliation(s)
- Chunfang Gu
- From the Laboratory of Signal Transduction, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina, 27709
| | - Hoai-Nghia Nguyen
- From the Laboratory of Signal Transduction, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina, 27709
| | - Alexandre Hofer
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Henning J Jessen
- Institute of Organic Chemistry, Albert Ludwigs University, Albertstrasse 21, 79104 Freiburg, Germany, and
| | - Xuming Dai
- Division of Cardiology, McAllister Heart Institute, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Huanchen Wang
- From the Laboratory of Signal Transduction, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina, 27709
| | - Stephen B Shears
- From the Laboratory of Signal Transduction, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina, 27709,
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16
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Thomas MP, Potter BVL. The enzymes of human diphosphoinositol polyphosphate metabolism. FEBS J 2013; 281:14-33. [PMID: 24152294 PMCID: PMC4063336 DOI: 10.1111/febs.12575] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 09/10/2013] [Accepted: 10/15/2013] [Indexed: 12/22/2022]
Abstract
Diphospho-myo-inositol polyphosphates have many roles to play, including roles in apoptosis, vesicle trafficking, the response of cells to stress, the regulation of telomere length and DNA damage repair, and inhibition of the cyclin-dependent kinase Pho85 system that monitors phosphate levels. This review focuses on the three classes of enzymes involved in the metabolism of these compounds: inositol hexakisphosphate kinases, inositol hexakisphosphate and diphosphoinositol-pentakisphosphate kinases and diphosphoinositol polyphosphate phosphohydrolases. However, these enzymes have roles beyond being mere catalysts, and their interactions with other proteins have cellular consequences. Through their interactions, the three inositol hexakisphosphate kinases have roles in exocytosis, diabetes, the response to infection, and apoptosis. The two inositol hexakisphosphate and diphosphoinositol-pentakisphosphate kinases influence the cellular response to phosphatidylinositol (3,4,5)-trisphosphate and the migration of pleckstrin homology domain-containing proteins to the plasma membrane. The five diphosphoinositol polyphosphate phosphohydrolases interact with ribosomal proteins and transcription factors, as well as proteins involved in membrane trafficking, exocytosis, ubiquitination and the proteasomal degradation of target proteins. Possible directions for future research aiming to determine the roles of these enzymes are highlighted.
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Affiliation(s)
- Mark P Thomas
- Department of Pharmacy & Pharmacology, University of Bath, UK
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17
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Gokhale NA, Zaremba A, Janoshazi AK, Weaver JD, Shears SB. PPIP5K1 modulates ligand competition between diphosphoinositol polyphosphates and PtdIns(3,4,5)P3 for polyphosphoinositide-binding domains. Biochem J 2013; 453:413-26. [PMID: 23682967 PMCID: PMC3931004 DOI: 10.1042/bj20121528] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We describe new signalling consequences for PPIP5K1 (diphosphoinositol pentakisphosphate kinase type 1)-mediated phosphorylation of InsP6 and 5-InsP7 to 1-InsP7 and InsP8. In NIH 3T3 cells, either hyperosmotic stress or receptor activation by PDGF (platelet-derived growth factor) promoted translocation of PPIP5K1 from the cytoplasm to the plasma membrane. The PBD1 (polyphosphoinositide-binding domain) in PPIP5K1 recapitulated that translocation. Mutagenesis of PBD1 to reduce affinity for PtdIns(3,4,5)P3 prevented translocation. Using surface plasmon resonance, we found that PBD1 association with vesicular PtdIns(3,4,5)P3 was inhibited by InsP6 and diphosphoinositol polyphosphates. However, the inhibition by PPIP5K1 substrates (IC50: 5-InsP7=5 μM and InsP6=7 μM) was substantially more potent than that of the PPIP5K1 products (IC50: InsP8=32 μM and 1-InsP7=43 μM). This rank order of ligand competition with PtdIns(3,4,5)P3 was also exhibited by the PH (pleckstrin homology) domains of Akt (also known as protein kinase B), GRP1 (general receptor for phosphoinositides 1) and SIN1 (stress-activated protein kinase-interaction protein 1). We propose that, in vivo, PH domain binding of InsP6 and 5-InsP7 suppresses inappropriate signalling ('noise') from stochastic increases in PtdIns(3,4,5)P3. That restraint may be relieved by localized depletion of InsP6 and 5-InsP7 at the plasma membrane following PPIP5K1 recruitment. We tested this hypothesis in insulin-stimulated L6 myoblasts, using mTOR (mechanistic/mammalian target of rapamycin)-mediated phosphorylation of Akt on Ser473 as a readout for SIN1-mediated translocation of mTORC (mTOR complex) 2 to the plasma membrane [Zoncu, Efeyan and Sabatini (2011) Nat. Rev. Mol. Cell Biol. 12, 21-35]. Knockdown of PPIP5K1 expression was associated with a 40% reduction in Ser473 phosphorylation. A common feature of PtdIns(3,4,5)P3-based signalling cascades may be their regulation by PPIP5K1.
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Affiliation(s)
- Nikhil A. Gokhale
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC 27709, U.S.A
| | - Angelika Zaremba
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC 27709, U.S.A
| | - Agnes K. Janoshazi
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC 27709, U.S.A
| | - Jeremy D. Weaver
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC 27709, U.S.A
| | - Stephen B. Shears
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, NC 27709, U.S.A
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18
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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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19
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Zhou Y, Wu S, Wang H, Hayakawa Y, Bird GS, Shears SB. Activation of PLC by an endogenous cytokine (GBP) in Drosophila S3 cells and its application as a model for studying inositol phosphate signalling through ITPK1. Biochem J 2012; 448:273-83. [PMID: 22928859 PMCID: PMC3925326 DOI: 10.1042/bj20120730] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Using immortalized [3H]inositol-labelled S3 cells, we demonstrated in the present study that various elements of the inositol phosphate signalling cascade are recruited by a Drosophila homologue from a cytokine family of so-called GBPs (growth-blocking peptides). HPLC analysis revealed that dGBP (Drosophila GBP) elevated Ins(1,4,5)P3 levels 9-fold. By using fluorescent Ca2+ probes, we determined that dGBP initially mobilized Ca2+ from intracellular pools; the ensuing depletion of intracellular Ca2+ stores by dGBP subsequently activated a Ca2+ entry pathway. The addition of dsRNA (double-stranded RNA) to knock down expression of the Drosophila Ins(1,4,5)P3 receptor almost completely eliminated mobilization of intracellular Ca2+ stores by dGBP. Taken together, the results of the present study describe a classical activation of PLC (phospholipase C) by dGBP. The peptide also promoted increases in the levels of other inositol phosphates with signalling credentials: Ins(1,3,4,5)P4, Ins(1,4,5,6)P4 and Ins(1,3,4,5,6)P5. These results greatly expand the regulatory repertoire of the dGBP family, and also characterize S3 cells as a model for studying the regulation of inositol phosphate metabolism and signalling by endogenous cell-surface receptors. We therefore created a cell-line (S3ITPK1) in which heterologous expression of human ITPK (inositol tetrakisphosphate kinase) was controlled by an inducible metallothionein promoter. We found that dGBP-stimulated S3ITPK1 cells did not synthesize Ins(3,4,5,6)P4, contradicting a hypothesis that the PLC-coupled phosphotransferase activity of ITPK1 [Ins(1,3,4,5,6)P5+Ins(1,3,4)P3→Ins(3,4,5,6)P4+Ins(1,3,4,6)P4] is driven solely by the laws of mass action [Chamberlain, Qian, Stiles, Cho, Jones, Lesley, Grabau, Shears and Spraggon (2007) J. Biol. Chem. 282, 28117-28125]. This conclusion represents a fundamental breach in our understanding of ITPK1 signalling.
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Affiliation(s)
- Yixing Zhou
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, U.S.A
| | - Shilan Wu
- Calcium Regulation Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, U.S.A
| | - Huanchen Wang
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, U.S.A
| | - Yoichi Hayakawa
- Department of Applied Biological Sciences, Saga University, Honjo-1, Saga 840-8502, Japan
| | - Gary S. Bird
- Calcium Regulation Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, U.S.A
| | - Stephen B. Shears
- Inositol Signaling Section, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, U.S.A
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20
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Abstract
Phospholipase C (PLC) converts phosphatidylinositol 4,5-bisphosphate (PIP(2)) to inositol 1,4,5-trisphosphate (IP(3)) and diacylglycerol (DAG). DAG and IP(3) each control diverse cellular processes and are also substrates for synthesis of other important signaling molecules. PLC is thus central to many important interlocking regulatory networks. Mammals express six families of PLCs, each with both unique and overlapping controls over expression and subcellular distribution. Each PLC also responds acutely to its own spectrum of activators that includes heterotrimeric G protein subunits, protein tyrosine kinases, small G proteins, Ca(2+), and phospholipids. Mammalian PLCs are autoinhibited by a region in the catalytic TIM barrel domain that is the target of much of their acute regulation. In combination, the PLCs act as a signaling nexus that integrates numerous signaling inputs, critically governs PIP(2) levels, and regulates production of important second messengers to determine cell behavior over the millisecond to hour timescale.
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Affiliation(s)
- Ganesh Kadamur
- Department of Pharmacology, Molecular Biophysics Graduate Program and Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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21
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Abstract
Inositol serves as a module for the generation of a high level of molecular diversity through the combinatorial attachment and removal of phosphate groups. The array of potential inositol-containing molecules is further expanded by the generation of diphospho inositol polyphosphates, commonly referred as inositol pyrophosphates. All eukaryotic cells possess inositol pyrophosphates containing one or more diphospho- moieties. The metabolism of this class of molecules is highly dynamic, and the enzymes responsible for their metabolism are evolutionary conserved. This new, exciting class of molecules are uniquely chracterized by a high energetic diphospho- bound that is able to participate in phosphotrasfer reactions thereby generating pyrophosphorylation of protein. However, allosteric mechanisms of action have been also proposed. In the past decade several disparate nuclear and cytoplasmic functions have been attributed to inositol pyrophosphates, ranging from intracellular trafficking to telomere length control and from regulating apoptotic process to stimulating insulin secretion. The extraordinary range of cellular function controlled by inositol pyrophosphate underline their great importance.
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Affiliation(s)
- Adolfo Saiardi
- MRC-LMCB, Department of Cell and Developmental Biology, University College London, Gower Street, WC1E 6BT, London, UK,
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Shears SB, Ganapathi SB, Gokhale NA, Schenk TMH, Wang H, Weaver JD, Zaremba A, Zhou Y. Defining signal transduction by inositol phosphates. Subcell Biochem 2012; 59:389-412. [PMID: 22374098 PMCID: PMC3925325 DOI: 10.1007/978-94-007-3015-1_13] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Ins(1,4,5)P(3) is a classical intracellular messenger: stimulus-dependent changes in its levels elicits biological effects through its release of intracellular Ca(2+) stores. The Ins(1,4,5)P(3) response is "switched off" by its metabolism to a range of additional inositol phosphates. These metabolites have themselves come to be collectively described as a signaling "family". The validity of that latter definition is critically examined in this review. That is, we assess the strength of the hypothesis that Ins(1,4,5)P(3) metabolites are themselves "classical" signals. Put another way, what is the evidence that the biological function of a particular inositol phosphate depends upon stimulus dependent changes in its levels? In this assessment, examples of an inositol phosphate acting as a cofactor (i.e. its function is not stimulus-dependent) do not satisfy our signaling criteria. We conclude that Ins(3,4,5,6)P(4) is, to date, the only Ins(1,4,5)P(3) metabolite that has been validated to act as a second messenger.
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Key Words
- adenosine deaminase
- akt
- β-cells
- calcium
- camp
- camkii
- chloride channel
- clc3
- compartmentalization
- dna repair
- endosomes
- erk
- frizzled receptor
- gap1ip4bp
- mrna export
- ins(1,4,5)p3
- ins(1,4,5)p4 receptor
- ins(1,3,4)p3
- ins(1,3,4,5)p4
- ins(1,3,4,5)p4 receptor
- ins(1,4,5,6)p4
- ins(3,4,5,6)p4
- ins(1,3,4,5,6)p5
- insp6
- insulin
- ipmk
- ipk2
- ip5k
- itp
- itpk1
- itpkb
- lymphocytes
- ku
- neutrophils
- protein phosphatase
- ptdins(4,5)p2
- ptdins(3,4,5)p3
- ph domain
- pten
- rasa3
- transcription
- wnt ligand
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Affiliation(s)
- Stephen B Shears
- Inositol Signaling Section, Laboratory of Signal Transduction, NIEHS, NIH, DHHS, Research Triangle Park, 27709, NC, USA, USA,
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An SW, Cha SK, Yoon J, Chang S, Ross EM, Huang CL. WNK1 promotes PIP₂ synthesis to coordinate growth factor and GPCR-Gq signaling. Curr Biol 2011; 21:1979-87. [PMID: 22119528 DOI: 10.1016/j.cub.2011.11.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 10/04/2011] [Accepted: 11/01/2011] [Indexed: 11/27/2022]
Abstract
BACKGROUND PLC-β signaling is generally thought to be mediated by allosteric activation by G proteins and Ca(2+). Although availability of the phosphatidylinositol-4,5-biphosphate (PIP(2)) substrate is limiting in some cases, its production has not been shown to be independently regulated as a signaling mechanism. WNK1 protein kinase is known to regulate ion homeostasis and cause hypertension when expression is increased by gene mutations. However, its signaling functions remain largely elusive. RESULTS Using diacylglycerol-stimulated TRPC6 and inositol trisphosphate-mediated Ca(2+) transients as cellular biosensors, we show that WNK1 stimulates PLC-β signaling in cells by promoting the synthesis of PIP(2) via stimulation of phosphatidylinositol 4-kinase IIIα. WNK1 kinase activity is not required. Stimulation of PLC-β by WNK1 and by Gα(q) are synergistic; WNK1 activity is essential for regulation of PLC-β signaling by G(q)-coupled receptors, and basal input from G(q) is necessary for WNK1 signaling via PLC-β. WNK1 further amplifies PLC-β signaling when it is phosphorylated by Akt kinase in response to insulin-like growth factor. CONCLUSIONS WNK1 is a novel regulator of PLC-β that acts by controlling substrate availability. WNK1 thereby coordinates signaling between G protein and Akt kinase pathways. Because PIP(2) is itself a signaling molecule, regulation of PIP(2) synthesis by WNK1 also allows the cell to initiate PLC signaling while independently controlling the effects of PIP(2) on other targets. These findings describe a new signaling pathway for Akt-activating growth factors, a mechanism for G protein-growth factor crosstalk, and a means to independently control PLC signaling and PIP(2) availability.
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Affiliation(s)
- Sung-Wan An
- Department of Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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Receptor-dependent compartmentalization of PPIP5K1, a kinase with a cryptic polyphosphoinositide binding domain. Biochem J 2011; 434:415-26. [PMID: 21222653 DOI: 10.1042/bj20101437] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The inositol pyrophosphates are multifunctional signalling molecules. One of the families of enzymes that synthesize the inositol pyrophosphates are the Vip1/PPIP5Ks (PP-InsP5 kinases). The kinase domains in Vip1/PPIP5Ks have been mapped to their N-terminus. Each of these proteins also possess a phosphatase-like domain of unknown significance. In the present study, we show that this phosphatase-like domain is not catalytically active. Instead, by using SPR (surface plasmon resonance) to study protein binding to immobilized lipid vesicles, we show that this domain is specialized for binding PtdIns(3,4,5)P3 (PPIP5K1 K(d)=96 nM; PPIP5K2 K(d)=705 nM). Both PtdIns(3,4)P2 and PtdIns(4,5)P2 are significantly weaker ligands, and no significant binding of PtdIns(3,5)P2 was detected. We confirm the functional importance of this domain in inositol lipid binding by site-directed mutagenesis. We present evidence that the PtdIns(3,4,5)P3-binding domain is an unusual hybrid, in which a partial PH (pleckstrin homology) consensus sequence is spliced into the phosphatase-like domain. Agonist-dependent activation of the PtdIns 3-kinase pathway in NIH 3T3 cells drives translocation of PPIP5K1 from the cytosol to the plasma membrane. We have therefore demonstrated receptor-regulated compartmentalization of inositol pyrophosphate synthesis in mammalian cells.
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Shears SB, Gokhale NA, Wang H, Zaremba A. Diphosphoinositol polyphosphates: what are the mechanisms? ACTA ACUST UNITED AC 2010; 51:13-25. [PMID: 21035493 DOI: 10.1016/j.advenzreg.2010.09.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Accepted: 09/17/2010] [Indexed: 12/30/2022]
Abstract
In countries where adulthood is considered to be attained at age eighteen, 2011 can be the point at which the diphosphoinositol polyphosphates might formally be described as "coming of age", since these molecules were first fully defined in 1993 (Menniti et al., 1993; Stephens et al., 1993b). But from a biological perspective, these polyphosphates cannot quite be considered to have matured into the status of being independently-acting intracellular signals. This review has discussed several of the published proposals for mechanisms by which the diphosphoinositol polyphosphates might act. We have argued that all of these hypotheses need further development.We also still do not know a single molecular mechanism by which a change in the levels of a particular diphosphoinositol polyphosphate can be controlled. Yet, despite all these gaps in our understanding, there is an enduring anticipation that these molecules have great potential in the signaling field. Reflecting our expectations of all teenagers, it should be our earnest hope that in the near future the diphosphoinositol polyphosphates will finally grow up.
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Affiliation(s)
- Stephen B Shears
- Inositol Signaling Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA.
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Abstract
Lipid-derived inositol phosphates (InsPs) comprise a family of second messengers that arise through the action of six classes of InsP kinases, generally referred to as IPKs. Genetic studies have indicated that InsPs play critical roles in embryonic development, but the mechanisms of action for InsPs in mammalian cellular function are largely unknown. This chapter outlines a method for manipulating cellular InsP profiles through the coexpression of a constitutively active G protein and various IPKs. It provides a mechanism by which the metabolism of a variety of InsPs can be upregulated, enabling the evaluation of the effects of these InsPs on cellular functions.
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King J, Keim M, Teo R, Weening KE, Kapur M, McQuillan K, Ryves J, Rogers B, Dalton E, Williams RSB, Harwood AJ. Genetic control of lithium sensitivity and regulation of inositol biosynthetic genes. PLoS One 2010; 5:e11151. [PMID: 20567601 PMCID: PMC2887444 DOI: 10.1371/journal.pone.0011151] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Accepted: 03/30/2010] [Indexed: 12/12/2022] Open
Abstract
Lithium (Li(+)) is a common treatment for bipolar mood disorder, a major psychiatric illness with a lifetime prevalence of more than 1%. Risk of bipolar disorder is heavily influenced by genetic predisposition, but is a complex genetic trait and, to date, genetic studies have provided little insight into its molecular origins. An alternative approach is to investigate the genetics of Li(+) sensitivity. Using the social amoeba Dictyostelium, we previously identified prolyl oligopeptidase (PO) as a modulator of Li(+) sensitivity. In a link to the clinic, PO enzyme activity is altered in bipolar disorder patients. Further studies demonstrated that PO is a negative regulator of inositol(1,4,5)trisphosphate (IP(3)) synthesis, a Li(+) sensitive intracellular signal. However, it was unclear how PO could influence either Li(+) sensitivity or risk of bipolar disorder. Here we show that in both Dictyostelium and cultured human cells PO acts via Multiple Inositol Polyphosphate Phosphatase (Mipp1) to control gene expression. This reveals a novel, gene regulatory network that modulates inositol metabolism and Li(+) sensitivity. Among its targets is the inositol monophosphatase gene IMPA2, which has also been associated with risk of bipolar disorder in some family studies, and our observations offer a cellular signalling pathway in which PO activity and IMPA2 gene expression converge.
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Affiliation(s)
- Jason King
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Melanie Keim
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Regina Teo
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Karin E. Weening
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Mridu Kapur
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Karina McQuillan
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Jonathan Ryves
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Ben Rogers
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Emma Dalton
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Robin S. B. Williams
- School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, United Kingdom
| | - Adrian J. Harwood
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
- * E-mail:
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Monserrate JP, York JD. Inositol phosphate synthesis and the nuclear processes they affect. Curr Opin Cell Biol 2010; 22:365-73. [DOI: 10.1016/j.ceb.2010.03.006] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Revised: 03/03/2010] [Accepted: 03/04/2010] [Indexed: 01/30/2023]
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Zebrafish inositol polyphosphate kinases: new effectors of cilia and developmental signaling. ACTA ACUST UNITED AC 2009; 50:309-23. [PMID: 19914277 DOI: 10.1016/j.advenzreg.2009.10.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Abstract
The inositol polyphosphate family of small, cytosolic molecules has a prominent place in the field of cell signalling, and inositol pyrophosphates are the most recent addition to this large family. First identified in 1993, they have since been found in all eukaryotic organisms studied. The defining feature of inositol pyrophosphates is the presence of the characteristic 'high energy' pyrophosphate group, which immediately attracted interest in them as possible signalling molecules. In addition to their unique 'high energy' pyrophosphate bond, their concentration in the cell is tightly regulated with an extremely rapid turnover. This, together with the history of other inositol polyphosphates, makes it likely that they have an important role in intracellular signalling involving some basic cellular processes. This hypothesis is supported by the surprisingly wide range of cellular functions where inositol pyrophosphates seem to be involved. A seminal finding was that inositol pyrophosphates are able to directly phosphorylate pre-phosphorylated proteins, thereby identifying an entirely new post-translational protein modification, namely serine-pyrophosphorylation. Rapid progress has been made in characterising the metabolism of these molecules in the 15 years since their first identification. However, their detailed signalling role in specific cellular processes and in the context of relevant physiological cues has developed more slowly, particularly in mammalian system. We will discuss inositol pyrophosphates from the cell signalling perspective, analysing how their intracellular concentration is modulated, what their possible molecular mechanisms of action are, together with the physiological consequences of this novel form of signalling.
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Affiliation(s)
- Adam Burton
- Medical Research Council, Cell Biology Unit, Laboratory for Molecular Cell Biology, Department of Cell and Developmental Biology, University College London, London, UK
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Abstract
The diphosphoinositol polyphosphates ("inositol pyrophosphates") are a specialized subgroup of the inositol phosphate signaling family. This review proposes that many of the current data concerning the metabolic turnover and biological effects of the diphosphoinositol polyphosphates are linked by a common theme: these polyphosphates act as metabolic messengers. This review will also discuss the latest proposals concerning possible molecular mechanisms of action of this intriguing class of molecules.
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Affiliation(s)
- Stephen B Shears
- Inositide Signaling Group, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA.
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Lin H, Fridy PC, Ribeiro AA, Choi JH, Barma DK, Vogel G, Falck JR, Shears SB, York JD, Mayr GW. Structural analysis and detection of biological inositol pyrophosphates reveal that the family of VIP/diphosphoinositol pentakisphosphate kinases are 1/3-kinases. J Biol Chem 2008; 284:1863-72. [PMID: 18981179 DOI: 10.1074/jbc.m805686200] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We have characterized the positional specificity of the mammalian and yeast VIP/diphosphoinositol pentakisphosphate kinase (PPIP5K) family of inositol phosphate kinases. We deployed a microscale metal dye detection protocol coupled to a high performance liquid chromatography system that was calibrated with synthetic and biologically synthesized standards of inositol pyrophosphates. In addition, we have directly analyzed the structures of biological inositol pyrophosphates using two-dimensional 1H-1H and 1H-31P nuclear magnetic resonance spectroscopy. Using these tools, we have determined that the mammalian and yeast VIP/PPIP5K family phosphorylates the 1/3-position of the inositol ring in vitro and in vivo. For example, the VIP/PPIP5K enzymes convert inositol hexakisphosphate to 1/3-diphosphoinositol pentakisphosphate. The latter compound has not previously been identified in any organism. We have also unequivocally determined that 1/3,5-(PP)2-IP4 is the isomeric structure of the bis-diphosphoinositol tetrakisphosphate that is synthesized by yeasts and mammals, through a collaboration between the inositol hexakisphosphate kinase and VIP/PPIP5K enzymes. These data uncover phylogenetic variability within the crown taxa in the structures of inositol pyrophosphates. For example, in the Dictyostelids, the major bis-diphosphoinositol tetrakisphosphate is 5,6-(PP)2-IP4 ( Laussmann, T., Eujen, R., Weisshuhn, C. M., Thiel, U., Falck, J. R., and Vogel, G. (1996) Biochem. J. 315, 715-725 ). Our study brings us closer to the goal of understanding the structure/function relationships that control specificity in the synthesis and biological actions of inositol pyrophosphates.
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Affiliation(s)
- Hongying Lin
- Institut für Biochemie und Molekularbiologie I: Zelluläre Signaltransduktion, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, D-20246 Hamburg, Germany
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Cheung JCY, Salerno B, Hanakahi LA. Evidence for an inositol hexakisphosphate-dependent role for Ku in mammalian nonhomologous end joining that is independent of its role in the DNA-dependent protein kinase. Nucleic Acids Res 2008; 36:5713-26. [PMID: 18776215 PMCID: PMC2553570 DOI: 10.1093/nar/gkn572] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Nonhomologous end-joining (NHEJ) is an important pathway for the repair of DNA double-strand breaks (DSBs) and plays a critical role in maintaining genomic stability in mammalian cells. While Ku70/80 (Ku) functions in NHEJ as part of the DNA-dependent protein kinase (DNA-PK), genetic evidence indicates that the role of Ku in NHEJ goes beyond its participation in DNA-PK. Inositol hexakisphosphate (IP(6)) was previously found to stimulate NHEJ in vitro and Ku was identified as an IP(6)-binding factor. Through mutational analysis, we identified a bipartite IP(6)-binding site in Ku and generated IP(6)-binding mutants that ranged from 1.22% to 58.48% of wild-type binding. Significantly, these Ku IP(6)-binding mutants were impaired for participation in NHEJ in vitro and we observed a positive correlation between IP(6) binding and NHEJ. Ku IP(6)-binding mutants were separation-of-function mutants that bound DNA and activated DNA-PK as well as wild-type Ku. Our observations identify a hitherto undefined IP(6)-binding site in Ku and show that this interaction is important for DSB repair by NHEJ in vitro. Moreover, these data indicate that in addition to binding of exposed DNA termini and activation of DNA-PK, the Ku heterodimer plays a role in mammalian NHEJ that is regulated by binding of IP(6).
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Affiliation(s)
- Joyce C Y Cheung
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, MD 21205, USA
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Ivey ME, Osman N, Little PJ. Endothelin-1 signalling in vascular smooth muscle: pathways controlling cellular functions associated with atherosclerosis. Atherosclerosis 2008; 199:237-47. [PMID: 18436225 DOI: 10.1016/j.atherosclerosis.2008.03.006] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 03/04/2008] [Accepted: 03/10/2008] [Indexed: 12/16/2022]
Abstract
Atherosclerosis is the primary ischaemic vascular condition underlying a majority of cardiovascular disease related deaths. Endothelin-1 is a vasoactive peptide agent upregulated in atherosclerosis and in conjunction with its G protein-coupled receptors exerts diverse actions on all cells of the vasculature in particular vascular smooth muscle cells (VSMC). The effects of endothelin-1 include cell proliferation, migration and contraction, and the induction of extracellular matrix components and growth factors. VSMC as the major component of the neointima in atherosclerotic plaques accordingly play a key role in atherogenesis. In this review we examine classic and novel signalling pathways activated by endothelin-1 in VSMC (including phospholipase C, adenylate cyclase, Rho kinase, transactivation of receptor tyrosine kinases, mitogen activated protein kinase cascades and beta-arrestin) and their likely impact on the development and progression of atherosclerosis.
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Affiliation(s)
- Melanie E Ivey
- Cell Biology of Diabetes Laboratory, Baker Heart Research Institute, Melbourne, Victoria, Australia
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