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Yu J, Leibiger B, Yang SN, Shears SB, Leibiger IB, Berggren PO, Barker CJ. Multiple Inositol Polyphosphate Phosphatase Compartmentalization Separates Inositol Phosphate Metabolism from Inositol Lipid Signaling. Biomolecules 2023; 13:885. [PMID: 37371464 DOI: 10.3390/biom13060885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 05/15/2023] [Accepted: 05/18/2023] [Indexed: 06/29/2023] Open
Abstract
Multiple inositol polyphosphate phosphatase (MINPP1) is an enigmatic enzyme that is responsible for the metabolism of inositol hexakisphosphate (InsP6) and inositol 1,3,4,5,6 pentakisphosphate (Ins(1,3,4,5,6)P5 in mammalian cells, despite being restricted to the confines of the ER. The reason for this compartmentalization is unclear. In our previous studies in the insulin-secreting HIT cell line, we expressed MINPP1 in the cytosol to artificially reduce the concentration of these higher inositol phosphates. Undocumented at the time, we noted cytosolic MINPP1 expression reduced cell growth. We were struck by the similarities in substrate preference between a number of different enzymes that are able to metabolize both inositol phosphates and lipids, notably IPMK and PTEN. MINPP1 was first characterized as a phosphatase that could remove the 3-phosphate from inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4). This molecule shares strong structural homology with the major product of the growth-promoting Phosphatidyl 3-kinase (PI3K), phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) and PTEN can degrade both this lipid and Ins(1,3,4,5)P4. Because of this similar substrate preference, we postulated that the cytosolic version of MINPP1 (cyt-MINPP1) may not only attack inositol polyphosphates but also PtdIns(3,4,5)P3, a key signal in mitogenesis. Our experiments show that expression of cyt-MINPP1 in HIT cells lowers the concentration of PtdIns(3,4,5)P3. We conclude this reflects a direct effect of MINPP1 upon the lipid because cyt-MINPP1 actively dephosphorylates synthetic, di(C4:0)PtdIns(3,4,5)P3 in vitro. These data illustrate the importance of MINPP1's confinement to the ER whereby important aspects of inositol phosphate metabolism and inositol lipid signaling can be separately regulated and give one important clarification for MINPP1's ER seclusion.
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Affiliation(s)
- Jia Yu
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
| | - Barbara Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
| | - Shao-Nian Yang
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
| | - Stephen B Shears
- Inositol Signaling Section, NIEHS, 111, Alexander Drive, Research Triangle Park, Durham, NC 27709, USA
| | - Ingo B Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
| | - Christopher J Barker
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
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Sun J, Singaram I, Soflaee MH, Cho W. A direct fluorometric activity assay for lipid kinases and phosphatases. J Lipid Res 2020; 61:945-952. [PMID: 32341006 PMCID: PMC7269761 DOI: 10.1194/jlr.d120000794] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 04/24/2020] [Indexed: 11/20/2022] Open
Abstract
Lipid kinases and phosphatases play key roles in cell signaling and regulation, are implicated in many human diseases, and are thus attractive targets for drug development. Currently, no direct in vitro activity assay is available for these important enzymes, which hampers mechanistic studies as well as high-throughput screening of small molecule modulators. Here, we report a highly sensitive and quantitative assay employing a ratiometric fluorescence sensor that directly and specifically monitors the real-time concentration change of a single lipid species. Because of its modular design, the assay system can be applied to a wide variety of lipid kinases and phosphatases, including class I phosphoinositide 3-kinase (PI3K) and phosphatase and tensin homolog (PTEN). When applied to PI3K, the assay provided detailed mechanistic information about the product inhibition and substrate acyl-chain selectivity of PI3K and enabled rapid evaluation of small molecule inhibitors. We also used this assay to quantitatively determine the substrate specificity of PTEN, providing new insight into its physiological function. In summary, we have developed a fluorescence-based real-time assay for PI3K and PTEN that we anticipate could be adapted to measure the activities of other lipid kinases and phosphatases with high sensitivity and accuracy.
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Affiliation(s)
- Jiachen Sun
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607
| | - Indira Singaram
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607
| | | | - Wonhwa Cho
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607. mailto:
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Bonjoch L, Mur P, Arnau-Collell C, Vargas-Parra G, Shamloo B, Franch-Expósito S, Pineda M, Capellà G, Erman B, Castellví-Bel S. Approaches to functionally validate candidate genetic variants involved in colorectal cancer predisposition. Mol Aspects Med 2019; 69:27-40. [PMID: 30935834 DOI: 10.1016/j.mam.2019.03.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 03/26/2019] [Accepted: 03/26/2019] [Indexed: 02/07/2023]
Abstract
Most next generation sequencing (NGS) studies identified candidate genetic variants predisposing to colorectal cancer (CRC) but do not tackle its functional interpretation to unequivocally recognize a new hereditary CRC gene. Besides, germline variants in already established hereditary CRC-predisposing genes or somatic variants share the same need when trying to categorize those with relevant significance. Functional genomics approaches have an important role in identifying the causal links between genetic architecture and phenotypes, in order to decipher cellular function in health and disease. Therefore, functional interpretation of identified genetic variants by NGS platforms is now essential. Available approaches nowadays include bioinformatics, cell and molecular biology and animal models. Recent advances, such as the CRISPR-Cas9, ZFN and TALEN systems, have been already used as a powerful tool with this objective. However, the use of cell lines is of limited value due to the CRC heterogeneity and its close interaction with microenvironment. Access to tridimensional cultures or organoids and xenograft models that mimic the in vivo tissue architecture could revolutionize functional analysis. This review will focus on the application of state-of-the-art functional studies to better tackle new genes involved in germline predisposition to this neoplasm.
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Affiliation(s)
- Laia Bonjoch
- Gastroenterology Department, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), University of Barcelona, Barcelona, Spain
| | - Pilar Mur
- Hereditary Cancer Program, Catalan Institute of Oncology, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), ONCOBELL Program, L'Hospitalet de Llobregat, Barcelona, Spain; Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Spain
| | - Coral Arnau-Collell
- Gastroenterology Department, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), University of Barcelona, Barcelona, Spain
| | - Gardenia Vargas-Parra
- Hereditary Cancer Program, Catalan Institute of Oncology, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), ONCOBELL Program, L'Hospitalet de Llobregat, Barcelona, Spain; Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Spain
| | - Bahar Shamloo
- Molecular Biology, Genetics, and Bioengineering Department, Legacy Research Institute, Portland, OR, USA
| | - Sebastià Franch-Expósito
- Gastroenterology Department, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), University of Barcelona, Barcelona, Spain
| | - Marta Pineda
- Hereditary Cancer Program, Catalan Institute of Oncology, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), ONCOBELL Program, L'Hospitalet de Llobregat, Barcelona, Spain; Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Spain
| | - Gabriel Capellà
- Hereditary Cancer Program, Catalan Institute of Oncology, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), ONCOBELL Program, L'Hospitalet de Llobregat, Barcelona, Spain; Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Spain
| | - Batu Erman
- Molecular Biology, Genetics and Bioengineering Program, Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul, Turkey
| | - Sergi Castellví-Bel
- Gastroenterology Department, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), University of Barcelona, Barcelona, Spain.
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Liu C, Deb S, Ferreira VS, Xu E, Baumgart T. Kinetics of PTEN-mediated PI(3,4,5)P3 hydrolysis on solid supported membranes. PLoS One 2018; 13:e0192667. [PMID: 29447222 PMCID: PMC5813967 DOI: 10.1371/journal.pone.0192667] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 01/26/2018] [Indexed: 11/18/2022] Open
Abstract
Phosphatidylinositides play important roles in cellular signaling and migration. Phosphatidylinositol-3,4,5-trisphosphate (PI(3,4,5)P3) is an important phosphatidylinositide because it acts as a secondary messenger to trigger cell movement and proliferation. A high level of PI(3,4,5)P3 at the plasma membrane is known to contribute to tumorigenesis. One key enzyme that regulates PI(3,4,5)P3 levels at the plasma membrane is phosphatase and tensin homologue deleted on chromosome 10 (PTEN), which dephosphorylates PI(3,4,5)P3 through hydrolysis to form phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2). It has been reported that PI(4,5)P2 is involved in positive feedback in the PI(3,4,5)P3 hydrolysis by PTEN. However, how PI(3,4,5)P3 dephosphorylation by PTEN is regulated, is still under debate. How other PI(3,4,5)P3-binding proteins affect the dephosphorylation kinetics catalyzed by PTEN also remains unclear. Here, we develop a fluorescent-protein biosensor approach to study how PI(3,4,5)P3 dephosphorylation is regulated by PTEN as well as its membrane-mediated feedback mechanisms. Our observation of sigmoidal kinetics of the PI(3,4,5)P3 hydrolysis reaction supports the notion of autocatalysis in PTEN function. We developed a kinetic model to describe the observed reaction kinetics, which allowed us to i) distinguish between membrane-recruitment and allosteric activation of PTEN by PI(4,5)P2, ii) account for the influence of the biosensor on the observed reaction kinetics, and iii) demonstrate that all of these mechanisms contribute to the kinetics of PTEN-mediated catalysis.
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Affiliation(s)
- Chun Liu
- Department of Chemistry, School of Arts & Sciences, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Sanghamitra Deb
- Department of Chemistry, School of Arts & Sciences, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Vinicius S Ferreira
- Department of Chemistry, School of Arts & Sciences, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Eric Xu
- Department of Chemistry, School of Arts & Sciences, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Tobias Baumgart
- Department of Chemistry, School of Arts & Sciences, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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Spinelli L, Leslie NR. Assays to Measure PTEN Lipid Phosphatase Activity In Vitro from Purified Enzyme or Immunoprecipitates. Methods Mol Biol 2018; 1447:95-105. [PMID: 27514802 DOI: 10.1007/978-1-4939-3746-2_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
PTEN is a one of the most frequently mutated tumor suppressors in human cancers. It is essential for regulating diverse biological processes and through its lipid phosphatase activity regulates the PI 3-Kinase signaling pathway. Sensitive phosphatase assays are employed to study the catalytic activity of PTEN against phospholipid substrates. Here we describe protocols to assay PTEN lipid phosphatase activity using either purified enzyme (purified PTEN lipid phosphatase assay) or PTEN immunopurified from tissues or cultured cells (cellular IP PTEN lipid phosphatase assay) against vesicles containing radiolabeled PIP3 substrate.
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Affiliation(s)
- Laura Spinelli
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot Watt University, Nasmyth Building, Riccarton Campus, Edinburgh, EH14 4AS, UK
- Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Nicholas R Leslie
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot Watt University, Nasmyth Building, Riccarton Campus, Edinburgh, EH14 4AS, UK.
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Jones MM, Vanyo ST, Visser MB. The C-terminal region of the major outer sheath protein of Treponema denticola inhibits neutrophil chemotaxis. Mol Oral Microbiol 2017; 32:375-389. [PMID: 28296262 PMCID: PMC5585023 DOI: 10.1111/omi.12180] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/09/2017] [Indexed: 12/25/2022]
Abstract
Treponema denticola is an oral spirochete strongly associated with severe periodontal disease. A prominent virulence factor, the major outer sheath protein (Msp), disorients neutrophil chemotaxis by altering the cellular phosphoinositide balance, leading to impairment of downstream chemotactic events including actin rearrangement, Rac1 activation, and Akt activation in response to chemoattractant stimulation. The specific regions of Msp responsible for interactions with neutrophils remain unknown. In this study, we investigated the inhibitory effect of truncated Msp regions on neutrophil chemotaxis and associated signaling pathways. Murine neutrophils were treated with recombinant protein truncations followed by assessment of chemotaxis and associated signal pathway activation. Chemotaxis assays indicate sequences within the C-terminal region; particularly the first 130 amino acids, have the strongest inhibitory effect on neutrophil chemotaxis. Neutrophils incubated with the C-terminal region protein also demonstrated the greatest inhibition of Rac1 activation, increased phosphoinositide phosphatase activity, and decreased Akt activation; orchestrating impairment of chemotaxis. Furthermore, incubation with antibodies specific to only the C-terminal region blocked the Msp-induced inhibition of chemotaxis and denaturing the protein restored Rac1 activation. Msp from the strain OTK, with numerous amino acid substitutions throughout the polypeptide, including the C-terminal region compared with strain 35405, showed increased ability to impair neutrophil chemotaxis. Collectively, these results indicate that the C-terminal region of Msp is the most potent region to modulate neutrophil chemotactic signaling and that specific sequences and structures are likely to be required. Knowledge of how spirochetes dampen the neutrophil response is limited and Msp may represent a novel therapeutic target for periodontal disease.
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Affiliation(s)
- Megan M. Jones
- State University of New York at Buffalo, 3435 Main St, Buffalo, NY 14214, USA
| | - Stephen T. Vanyo
- State University of New York at Buffalo, 3435 Main St, Buffalo, NY 14214, USA
| | - Michelle B. Visser
- State University of New York at Buffalo, 3435 Main St, Buffalo, NY 14214, USA
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Arora N, Ghosh SS. Functional characterizations of interactive recombinant PTEN–silica nanoparticles for potential biomedical applications. RSC Adv 2016. [DOI: 10.1039/c6ra23036a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Nanosystem mediated successful stabilization and delivery of functional recombinant PTEN.
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Affiliation(s)
- Neha Arora
- Department of Biosciences and Bioengineering
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
| | - Siddhartha Sankar Ghosh
- Department of Biosciences and Bioengineering
- Indian Institute of Technology Guwahati
- Guwahati-781039
- India
- Centre for Nanotechnology
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Pulido R. A rapid guide to PTEN function. Methods 2015; 77-78:1-2. [PMID: 25843296 DOI: 10.1016/j.ymeth.2015.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Affiliation(s)
- Rafael Pulido
- Biocruces Health Research Institute, Barakaldo, Bizkaia, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Bizkaia, Spain
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