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Jin Y, Xue J. Lipid kinases PIP5Ks and PIP4Ks: potential drug targets for breast cancer. Front Oncol 2023; 13:1323897. [PMID: 38156113 PMCID: PMC10753794 DOI: 10.3389/fonc.2023.1323897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 11/29/2023] [Indexed: 12/30/2023] Open
Abstract
Phosphoinositides, a small group of lipids found in all cellular membranes, have recently garnered heightened attention due to their crucial roles in diverse biological processes and different diseases. Among these, phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), the most abundant bis-phosphorylated phosphoinositide within the signaling system, stands notably connected to breast cancer. Not only does it serve as a key activator of the frequently altered phosphatidylinositol 3-kinase (PI3K) pathway in breast cancer, but also its conversion to phosphatidylinositol-3,4,5-triphosphate (PI(3,4,5)P3) is an important direction for breast cancer research. The generation and degradation of phosphoinositides intricately involve phosphoinositide kinases. PI(4,5)P2 generation emanates from the phosphorylation of PI4P or PI5P by two lipid kinase families: Type I phosphatidylinositol-4-phosphate 5-kinases (PIP5Ks) and Type II phosphatidylinositol-5-phosphate 4-kinases (PIP4Ks). In this comprehensive review, we focus on these two lipid kinases and delineate their compositions and respective cellular localization. Moreover, we shed light on the expression patterns and functions of distinct isoforms of these kinases in breast cancer. For a deeper understanding of their functional dynamics, we expound upon various mechanisms governing the regulation of PIP5Ks and PIP4Ks activities. A summary of effective and specific small molecule inhibitors designed for PIP5Ks or PIP4Ks are also provided. These growing evidences support PIP5Ks and PIP4Ks as promising drug targets for breast cancer.
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Affiliation(s)
- Yue Jin
- Department of Molecular Diagnosis, Northern Jiangsu People’s Hospital, Yangzhou University Clinical Medical College, Yangzhou, China
| | - Jian Xue
- Department of Emergency Medicine, Yizheng People’s Hospital, Yangzhou University Clinical Medical College, Yangzhou, China
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2
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Rameh LE, Blind RD. 25 Years of PI5P. Front Cell Dev Biol 2023; 11:1272911. [PMID: 37849742 PMCID: PMC10577294 DOI: 10.3389/fcell.2023.1272911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 09/18/2023] [Indexed: 10/19/2023] Open
Abstract
The accidental discovery of PI5P (phosphatidylinositol-5-phosphate) was published 25 years ago, when PIP5K type II (phosphoinositide-4-phosphate 5-kinase) was shown to actually be a 4-kinase that uses PI5P as a substrate to generate PI(4,5)P2. Consequently, PIP5K type II was renamed to PI5P4K, or PIP4K for short, and PI5P became the last of the 7 signaling phosphoinositides to be discovered. Much of what we know about PI5P comes from genetic studies of PIP4K, as the pathways for PI5P synthesis, the downstream targets of PI5P and how PI5P affects cellular function all remain largely enigmatic. Nevertheless, PI5P and PI5P-dependent PI(4,5)P2 synthesis have been clearly implicated in metabolic homeostasis and in diseases such as cancer. Here, we review the past 25 years of PI5P research, with particular emphasis on the impact this small signaling lipid has on human health.
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Affiliation(s)
- Lucia E. Rameh
- Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Raymond D. Blind
- Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, TN, United States
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3
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Vidalle MC, Sheth B, Fazio A, Marvi MV, Leto S, Koufi FD, Neri I, Casalin I, Ramazzotti G, Follo MY, Ratti S, Manzoli L, Gehlot S, Divecha N, Fiume R. Nuclear Phosphoinositides as Key Determinants of Nuclear Functions. Biomolecules 2023; 13:1049. [PMID: 37509085 PMCID: PMC10377365 DOI: 10.3390/biom13071049] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 06/23/2023] [Accepted: 06/26/2023] [Indexed: 07/30/2023] Open
Abstract
Polyphosphoinositides (PPIns) are signalling messengers representing less than five per cent of the total phospholipid concentration within the cell. Despite their low concentration, these lipids are critical regulators of various cellular processes, including cell cycle, differentiation, gene transcription, apoptosis and motility. PPIns are generated by the phosphorylation of the inositol head group of phosphatidylinositol (PtdIns). Different pools of PPIns are found at distinct subcellular compartments, which are regulated by an array of kinases, phosphatases and phospholipases. Six of the seven PPIns species have been found in the nucleus, including the nuclear envelope, the nucleoplasm and the nucleolus. The identification and characterisation of PPIns interactor and effector proteins in the nucleus have led to increasing interest in the role of PPIns in nuclear signalling. However, the regulation and functions of PPIns in the nucleus are complex and are still being elucidated. This review summarises our current understanding of the localisation, biogenesis and physiological functions of the different PPIns species in the nucleus.
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Affiliation(s)
- Magdalena C Vidalle
- Inositide Laboratory, School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| | - Bhavwanti Sheth
- Inositide Laboratory, School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| | - Antonietta Fazio
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Maria Vittoria Marvi
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Stefano Leto
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Foteini-Dionysia Koufi
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Irene Neri
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Irene Casalin
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Giulia Ramazzotti
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Matilde Y Follo
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Stefano Ratti
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Lucia Manzoli
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Sonakshi Gehlot
- Inositide Laboratory, School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| | - Nullin Divecha
- Inositide Laboratory, School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| | - Roberta Fiume
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
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4
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Ong JY, Torres JZ. Cul3 substrate adaptor SPOP targets Nup153 for degradation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.13.540659. [PMID: 37293018 PMCID: PMC10245568 DOI: 10.1101/2023.05.13.540659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
SPOP is a Cul3 substrate adaptor responsible for degradation of many proteins related to cell growth and proliferation. Because mutation or misregulation of SPOP drives cancer progression, understanding the suite of SPOP substrates is important to understanding regulation of cell proliferation. Here, we identify Nup153, a component of the nuclear basket of the nuclear pore complex, as a novel substrate of SPOP. SPOP and Nup153 bind to each other and colocalize at the nuclear envelope and some nuclear foci in cells. The binding interaction between SPOP and Nup153 is complex and multivalent. Nup153 is ubiquitylated and degraded upon expression of SPOPWT but not its substrate binding-deficient mutant SPOPF102C. Depletion of SPOP via RNAi leads to Nup153 stabilization. Upon loss of SPOP, the nuclear envelope localization of spindle assembly checkpoint protein Mad1, which is tethered to the nuclear envelope by Nup153, is stronger. Altogether, our results demonstrate SPOP regulates Nup153 levels and expands our understanding of the role of SPOP in protein and cellular homeostasis.
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Affiliation(s)
- Joseph Y Ong
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Jorge Z Torres
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Jonsson Comprehensive Cancer Center, University of California, Los Angeles, Los Angeles, CA 90095, USA
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5
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Llorente A, Arora GK, Grenier SF, Emerling BM. PIP kinases: A versatile family that demands further therapeutic attention. Adv Biol Regul 2023; 87:100939. [PMID: 36517396 PMCID: PMC9992244 DOI: 10.1016/j.jbior.2022.100939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022]
Abstract
Phosphoinositides are membrane-localized phospholipids that regulate a plethora of essential cellular processes. These lipid signaling molecules are critical for cell homeostasis and therefore their levels are strictly regulated by the coordinated action of several families of lipid kinases and phosphatases. In this review, we provide a focused perspective on the phosphatidylinositol phosphate kinase (PIPK) family and the three subfamilies that compose it: Type I PIPKs or phosphatidylinositol-4-phosphate 5-kinases (PI4P5Ks), Type II PIPKs or phosphatidylinositol-5-phosphate 4-kinases (PI5P4Ks), and Type III PIPKs or phosphatidylinositol-3-phosphate 5-kinases (PIKfyve). Each subfamily is responsible for catalyzing a hydroxyl phosphorylation on specific phosphoinositide species to generate a double phosphorylated lipid, therefore regulating the levels of both substrate and product. Here, we summarize our current knowledge about the functions and regulation of each PIPK subfamily. Further, we highlight the roles of these kinases in various in vivo genetic models and give an overview of their involvement in multiple pathological conditions. The phosphoinositide field has been long focused on targeting PI3K signaling, but growing evidence suggests that it is time to draw attention to the other phosphoinositide kinases. The discovery of the involvement of PIPKs in the pathogenesis of multiple diseases has prompted substantial efforts to turn these enzymes into pharmacological targets. An increasingly refined knowledge of the biology of PIPKs in a variety of in vitro and in vivo models will facilitate the development of effective approaches for therapeutic intervention with the potential to translate into meaningful clinical benefits for patients suffering from cancer, immunological and infectious diseases, and neurodegenerative disorders.
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Affiliation(s)
- Alicia Llorente
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys, La Jolla, CA, 92037, USA
| | - Gurpreet K Arora
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys, La Jolla, CA, 92037, USA
| | - Shea F Grenier
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys, La Jolla, CA, 92037, USA
| | - Brooke M Emerling
- Cell and Molecular Biology of Cancer Program, Sanford Burnham Prebys, La Jolla, CA, 92037, USA.
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6
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Yang X, Zhu Q. SPOP in Cancer: Phenomena, Mechanisms and Its Role in Therapeutic Implications. Genes (Basel) 2022; 13:2051. [PMID: 36360288 PMCID: PMC9690554 DOI: 10.3390/genes13112051] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Revised: 10/14/2022] [Accepted: 11/04/2022] [Indexed: 11/15/2023] Open
Abstract
Speckle-type POZ (pox virus and zinc finger protein) protein (SPOP) is a cullin 3-based E3 ubiquitin ligase adaptor protein that plays a crucial role in ubiquitin-mediated protein degradation. Recently, SPOP has attracted major research attention as it is frequently mutated in a range of cancers, highlighting pleiotropic tumorigenic effects and associations with treatment resistance. Structurally, SPOP contains a functionally critical N-terminal meprin and TRAF homology (MATH) domain for many SPOP substrates. SPOP has two other domains, including the internal Bric-a-brac-Tramtrack/Broad (BTB) domain, which is linked with SPOP dimerization and binding to cullin3, and a C-terminal nuclear localization sequence (NLS). The dysregulation of SPOP-mediated proteolysis is associated with the development and progression of different cancers since abnormalities in SPOP function dysregulate cellular signaling pathways by targeting oncoproteins or tumor suppressors in a tumor-specific manner. SPOP is also involved in genome stability through its role in the DNA damage response and DNA replication. More recently, studies have shown that the expression of SPOP can be modulated in various ways. In this review, we summarize the current understanding of SPOP's functions in cancer and discuss how to design a rational therapeutic target.
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Affiliation(s)
| | - Qing Zhu
- Department of Abdominal Oncology, West China Hospital of Sichuan University, Chengdu 610041, China
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7
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The speckle-type POZ protein (SPOP) inhibits breast cancer malignancy by destabilizing TWIST1. Cell Death Dis 2022; 8:389. [PMID: 36115849 PMCID: PMC9482615 DOI: 10.1038/s41420-022-01182-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 08/31/2022] [Accepted: 09/05/2022] [Indexed: 12/21/2022]
Abstract
Epithelial-mesenchymal transition (EMT) inducing transcription factor TWIST1 plays a vital role in cancer metastasis. How the tumor-suppressive E3 ligase, speckle-type POZ protein (SPOP), regulates TWIST1 in breast cancer remains unknown. In this study, we report that SPOP physically interacts with, ubiquitinates, and destabilizes TWIST1. SPOP promotes K63-and K48-linked ubiquitination of TWIST1, predominantly at K73, thereby suppressing cancer cell migration and invasion. Silencing SPOP significantly enhances EMT, which accelerates breast cancer cell migration and invasiveness in vitro and lung metastasis in vivo. Clinically, SPOP is negatively correlated with the levels of TWIST1 in highly invasive breast carcinomas. Reduced SPOP expression, along with elevated TWIST1 levels, is associated with poor prognosis in advanced breast cancer patients, particularly those with metastatic triple-negative breast cancer (TNBC). Taken together, we have disclosed a new mechanism linking SPOP to TWIST1 degradation. Thus SPOP may serve as a prognostic marker and a potential therapeutic target for advanced TNBC patients.
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8
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Mandal P, Eswara K, Yerkesh Z, Kharchenko V, Zandarashvili L, Szczepski K, Bensaddek D, Jaremko Ł, Black BE, Fischle W. Molecular basis of hUHRF1 allosteric activation for synergistic histone modification binding by PI5P. SCIENCE ADVANCES 2022; 8:eabl9461. [PMID: 36001657 PMCID: PMC9401617 DOI: 10.1126/sciadv.abl9461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Accepted: 07/11/2022] [Indexed: 06/15/2023]
Abstract
Chromatin marks are recognized by distinct binding modules, many of which are embedded in multidomain proteins. How the different functionalities of such complex chromatin modulators are regulated is often unclear. Here, we delineated the interplay of the H3 amino terminus- and K9me-binding activities of the multidomain hUHRF1 protein. We show that the phosphoinositide PI5P interacts simultaneously with two distant flexible linker regions connecting distinct domains of hUHRF1. The binding is dependent on both, the polar head group, and the acyl part of the phospholipid and induces a conformational rearrangement juxtaposing the H3 amino terminus and K9me3 recognition modules of the protein. In consequence, the two features of the H3 tail are bound in a multivalent, synergistic manner. Our work highlights a previously unidentified molecular function for PI5P outside of the context of lipid mono- or bilayers and establishes a molecular paradigm for the allosteric regulation of complex, multidomain chromatin modulators by small cellular molecules.
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Affiliation(s)
- Papita Mandal
- Bioscience Program, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Kingdom of Saudi Arabia
| | - Karthik Eswara
- Bioscience Program, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Kingdom of Saudi Arabia
| | - Zhadyra Yerkesh
- Bioscience Program, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Kingdom of Saudi Arabia
| | - Vladlena Kharchenko
- Bioscience Program, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Kingdom of Saudi Arabia
| | - Levani Zandarashvili
- Department of Biochemistry and Biophysics, Penn Center for Genome Integrity, Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kacper Szczepski
- Bioscience Program, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Kingdom of Saudi Arabia
| | - Dalila Bensaddek
- Core Laboratories, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Kingdom of Saudi Arabia
| | - Łukasz Jaremko
- Bioscience Program, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Kingdom of Saudi Arabia
| | - Ben E. Black
- Department of Biochemistry and Biophysics, Penn Center for Genome Integrity, Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Wolfgang Fischle
- Bioscience Program, Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Kingdom of Saudi Arabia
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Wang YH, Sheetz MP. When PIP2 Meets p53: Nuclear Phosphoinositide Signaling in the DNA Damage Response. Front Cell Dev Biol 2022; 10:903994. [PMID: 35646908 PMCID: PMC9136457 DOI: 10.3389/fcell.2022.903994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 04/19/2022] [Indexed: 11/13/2022] Open
Abstract
The mechanisms that maintain genome stability are critical for preventing tumor progression. In the past decades, many strategies were developed for cancer treatment to disrupt the DNA repair machinery or alter repair pathway selection. Evidence indicates that alterations in nuclear phosphoinositide lipids occur rapidly in response to genotoxic stresses. This implies that nuclear phosphoinositides are an upstream element involved in DNA damage signaling. Phosphoinositides constitute a new signaling interface for DNA repair pathway selection and hence a new opportunity for developing cancer treatment strategies. However, our understanding of the underlying mechanisms by which nuclear phosphoinositides regulate DNA damage repair, and particularly the dynamics of those processes, is rather limited. This is partly because there are a limited number of techniques that can monitor changes in the location and/or abundance of nuclear phosphoinositide lipids in real time and in live cells. This review summarizes our current knowledge regarding the roles of nuclear phosphoinositides in DNA damage response with an emphasis on the dynamics of these processes. Based upon recent findings, there is a novel model for p53’s role with nuclear phosphoinositides in DNA damage response that provides new targets for synthetic lethality of tumors.
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10
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Novel insights into the SPOP E3 ubiquitin ligase: From the regulation of molecular mechanisms to tumorigenesis. Biomed Pharmacother 2022; 149:112882. [PMID: 35364375 DOI: 10.1016/j.biopha.2022.112882] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/13/2022] [Accepted: 03/23/2022] [Indexed: 11/20/2022] Open
Abstract
Ubiquitin-mediated protein degradation is the primary biological process by which protein abundance is regulated and protein homeostasis is maintained in eukaryotic cells. Speckle-type pox virus and zinc finger (POZ) protein (SPOP) is a typical substrate adaptor of the Cullin 3-RING ligase (CRL3) family; it serves as a bridge between the Cullin 3 (Cul3) scaffold protein and its substrates. In recent years, SPOP has received increasing attention because of its versatility in its regulatory pathways and the diversity of tumor types involved. Mechanistically, SPOP substrates are involved in a wide range of biological processes, and abnormalities in SPOP function perturb downstream biological processes and promote tumorigenesis. Additionally, liquid-liquid phase separation (LLPS), a potential mechanism of membraneless organelle formation, was recently found to mediate the self-triggered colocalization of substrates with higher-order oligomers of SPOP. Herein, we summarize the structure of SPOP and the specific mechanisms by which it mediates the efficient ubiquitination of substrates. Additionally, we review the biological functions of SPOP, the regulation of SPOP expression, the role of SPOP in tumorigenesis and its therapeutic value.
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11
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Borges-Araújo L, Fernandes F. Structure and Lateral Organization of Phosphatidylinositol 4,5-bisphosphate. Molecules 2020; 25:molecules25173885. [PMID: 32858905 PMCID: PMC7503891 DOI: 10.3390/molecules25173885] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/22/2020] [Accepted: 08/23/2020] [Indexed: 02/07/2023] Open
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is a minor but ubiquitous component of the inner leaflet of the plasma membrane of eukaryotic cells. However, due to its particular complex biophysical properties, it stands out from its neighboring lipids as one of the most important regulators of membrane-associated signaling events. Despite its very low steady-state concentration, PI(4,5)P2 is able to engage in a multitude of simultaneous cellular functions that are temporally and spatially regulated through the presence of localized transient pools of PI(4,5)P2 in the membrane. These pools are crucial for the recruitment, activation, and organization of signaling proteins and consequent regulation of downstream signaling. The present review showcases some of the most important PI(4,5)P2 molecular and biophysical properties as well as their impact on its membrane dynamics, lateral organization, and interactions with other biochemical partners.
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Affiliation(s)
- Luís Borges-Araújo
- iBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal;
- Correspondence:
| | - Fabio Fernandes
- iBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal;
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal
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12
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Chen M, Wen T, Horn HT, Chandrahas VK, Thapa N, Choi S, Cryns VL, Anderson RA. The nuclear phosphoinositide response to stress. Cell Cycle 2020; 19:268-289. [PMID: 31902273 PMCID: PMC7028212 DOI: 10.1080/15384101.2019.1711316] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Accumulating evidence reveals that nuclear phosphoinositides (PIs) serve as central signaling hubs that control a multitude of nuclear processes by regulating the activity of nuclear proteins. In response to cellular stressors, PIs accumulate in the nucleus and multiple PI isomers are synthesized by the actions of PI-metabolizing enzymes, kinases, phosphatases and phospholipases. By directly interacting with effector proteins, phosphoinositide signals transduce changes in cellular functions. Here we describe nuclear phosphoinositide signaling in multiple sub-nuclear compartments and summarize the literature that demonstrates roles for specific kinases, phosphatases, and phospholipases in the orchestration of nuclear phosphoinositide signaling in response to cellular stress. Additionally, we discuss the specific PI-protein complexes through which these lipids execute their functions by regulating the configuration, stability, and transcription activity of their effector proteins. Overall, our review provides a detailed landscape of the current understanding of the nuclear PI-protein interactome and its role in shaping the coordinated response to cellular stress.
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Affiliation(s)
- Mo Chen
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Tianmu Wen
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Hudson T. Horn
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | | | - Narendra Thapa
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Suyong Choi
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Vincent L. Cryns
- Department of Medicine, University of Wisconsin Carbone Cancer Center, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, USA
| | - Richard A. Anderson
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
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13
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Nuclear Phosphoinositides-Versatile Regulators of Genome Functions. Cells 2019; 8:cells8070649. [PMID: 31261688 PMCID: PMC6678639 DOI: 10.3390/cells8070649] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 06/21/2019] [Accepted: 06/25/2019] [Indexed: 12/17/2022] Open
Abstract
The many functions of phosphoinositides in cytosolic signaling were extensively studied; however, their activities in the cell nucleus are much less clear. In this review, we summarize data about their nuclear localization and metabolism, and review the available literature on their involvements in chromatin remodeling, gene transcription, and RNA processing. We discuss the molecular mechanisms via which nuclear phosphoinositides, in particular phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P2), modulate nuclear processes. We focus on PI(4,5)P2’s role in the modulation of RNA polymerase I activity, and functions of the nuclear lipid islets—recently described nucleoplasmic PI(4,5)P2-rich compartment involved in RNA polymerase II transcription. In conclusion, the high impact of the phosphoinositide–protein complexes on nuclear organization and genome functions is only now emerging and deserves further thorough studies.
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14
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Nuclear Phosphoinositides: Their Regulation and Roles in Nuclear Functions. Int J Mol Sci 2019; 20:ijms20122991. [PMID: 31248120 PMCID: PMC6627530 DOI: 10.3390/ijms20122991] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 05/22/2019] [Accepted: 06/17/2019] [Indexed: 12/29/2022] Open
Abstract
Polyphosphoinositides (PPIns) are a family of seven lipid messengers that regulate a vast array of signalling pathways to control cell proliferation, migration, survival and differentiation. PPIns are differentially present in various sub-cellular compartments and, through the recruitment and regulation of specific proteins, are key regulators of compartment identity and function. Phosphoinositides and the enzymes that synthesise and degrade them are also present in the nuclear membrane and in nuclear membraneless compartments such as nuclear speckles. Here we discuss how PPIns in the nucleus are modulated in response to external cues and how they function to control downstream signalling. Finally we suggest a role for nuclear PPIns in liquid phase separations that are involved in the formation of membraneless compartments within the nucleus.
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15
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Nakada-Tsukui K, Watanabe N, Maehama T, Nozaki T. Phosphatidylinositol Kinases and Phosphatases in Entamoeba histolytica. Front Cell Infect Microbiol 2019; 9:150. [PMID: 31245297 PMCID: PMC6563779 DOI: 10.3389/fcimb.2019.00150] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 04/23/2019] [Indexed: 12/11/2022] Open
Abstract
Phosphatidylinositol (PtdIns) metabolism is indispensable in eukaryotes. Phosphoinositides (PIs) are phosphorylated derivatives of PtdIns and consist of seven species generated by reversible phosphorylation of the inositol moieties at the positions 3, 4, and 5. Each of the seven PIs has a unique subcellular and membrane domain distribution. In the enteric protozoan parasite Entamoeba histolytica, it has been previously shown that the PIs phosphatidylinositol 3-phosphate (PtdIns3P), PtdIns(4,5)P2, and PtdIns(3,4,5)P3 are localized to phagosomes/phagocytic cups, plasma membrane, and phagocytic cups, respectively. The localization of these PIs in E. histolytica is similar to that in mammalian cells, suggesting that PIs have orthologous functions in E. histolytica. In contrast, the conservation of the enzymes that metabolize PIs in this organism has not been well-documented. In this review, we summarized the full repertoire of the PI kinases and PI phosphatases found in E. histolytica via a genome-wide survey of the current genomic information. E. histolytica appears to have 10 PI kinases and 23 PI phosphatases. It has a panel of evolutionarily conserved enzymes that generate all the seven PI species. However, class II PI 3-kinases, type II PI 4-kinases, type III PI 5-phosphatases, and PI 4P-specific phosphatases are not present. Additionally, regulatory subunits of class I PI 3-kinases and type III PI 4-kinases have not been identified. Instead, homologs of class I PI 3-kinases and PTEN, a PI 3-phosphatase, exist as multiple isoforms, which likely reflects that elaborate signaling cascades mediated by PtdIns(3,4,5)P3 are present in this organism. There are several enzymes that have the nuclear localization signal: one phosphatidylinositol phosphate (PIP) kinase, two PI 3-phosphatases, and one PI 5-phosphatase; this suggests that PI metabolism also has conserved roles related to nuclear functions in E. histolytica, as it does in model organisms.
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Affiliation(s)
- Kumiko Nakada-Tsukui
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Natsuki Watanabe
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan.,Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan
| | - Tomohiko Maehama
- Division of Molecular and Cellular Biology, Graduate School of Medicine, Kobe University, Kobe, Japan
| | - Tomoyoshi Nozaki
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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16
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Phosphatidylinositol 5 Phosphate (PI5P): From Behind the Scenes to the Front (Nuclear) Stage. Int J Mol Sci 2019; 20:ijms20092080. [PMID: 31035587 PMCID: PMC6539119 DOI: 10.3390/ijms20092080] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 04/20/2019] [Accepted: 04/23/2019] [Indexed: 12/11/2022] Open
Abstract
Phosphatidylinositol (PI)-related signaling plays a pivotal role in many cellular aspects, including survival, cell proliferation, differentiation, DNA damage, and trafficking. PI is the core of a network of proteins represented by kinases, phosphatases, and lipases which are able to add, remove or hydrolyze PI, leading to different phosphoinositide products. Among the seven known phosphoinositides, phosphatidylinositol 5 phosphate (PI5P) was the last to be discovered. PI5P presence in cells is very low compared to other PIs. However, much evidence collected throughout the years has described the role of this mono-phosphoinositide in cell cycles, stress response, T-cell activation, and chromatin remodeling. Interestingly, PI5P has been found in different cellular compartments, including the nucleus. Here, we will review the nuclear role of PI5P, describing how it is synthesized and regulated, and how changes in the levels of this rare phosphoinositide can lead to different nuclear outputs.
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17
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Ji P, Liang S, Li P, Xie C, Li J, Zhang K, Zheng X, Feng M, Li Q, Jiao H, Chi X, Zhao W, Zhang S, Wang X. Speckle-type POZ protein suppresses hepatocellular carcinoma cell migration and invasion via ubiquitin-dependent proteolysis of SUMO1/sentrin specific peptidase 7. Biochem Biophys Res Commun 2018; 502:30-42. [PMID: 29777712 DOI: 10.1016/j.bbrc.2018.05.115] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 05/16/2018] [Indexed: 02/07/2023]
Abstract
Hepatocellular carcinoma (HCC) is associated with high metastatic potential and high mortality. Accumulating evidence has demonstrated that speckle-type POZ protein (SPOP) is a key adaptor molecule of ubiquitination. However, the molecular mechanism of SPOP-mediated ubiquitination in HCC metastasis remains obscure. In the present study, our results indicated that SPOP expression was significantly downregulated in HCC and was associated with tumor size, differentiation and metastasis. Cox regression model showed that low SPOP expression was a risk factor related to the prognosis of HCC patients. Loss- and gain-of-function assays demonstrated that SPOP inhibited HCC cell migration and invasion in vitro. Mechanisitically, co-immunoprecipitation and ubiquitination assays revealed that SPOP recognized and bound SENP7 and promoted its degradation via ubiquitin-dependent proteolysis. Analysis of immunohistochemistry showed that vimentin expression was correlated negatively with SPOP and positively with SENP7. These results implied that increased degradation of SENP7 by overexpression of SPOP decreased vimentin levels, which in turn attenuated HCC cell metastasis. Moreover, in vivo assays showed that SPOP overexpression also significantly suppressed liver and lung metastases. In summary, SPOP inhibits HCC cell metastasis via ubiquitin-dependent SENP7 proteolysis and may thus serve as a new opinion for the prevention of HCC metastasis.
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Affiliation(s)
- Piyou Ji
- Department of Hepatobiliary Surgery, School of Clinical Medicine, Fujian Medical University, Fuzhou, Fujian, 350108, China
| | - Shaohua Liang
- Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, Fujian, 350108, China
| | - Pengtao Li
- Department of Hepatobiliary Surgery, School of Clinical Medicine, Fujian Medical University, Fuzhou, Fujian, 350108, China
| | - Chengrong Xie
- Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen Translational Medical Key Laboratory of Hepatobiliary and Pancreatic Tumor, Zhongshan Hospital Xiamen University, Xiamen, 361004, China
| | - Jie Li
- Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen Translational Medical Key Laboratory of Hepatobiliary and Pancreatic Tumor, Zhongshan Hospital Xiamen University, Xiamen, 361004, China
| | - Kang Zhang
- Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen Translational Medical Key Laboratory of Hepatobiliary and Pancreatic Tumor, Zhongshan Hospital Xiamen University, Xiamen, 361004, China
| | - Xuqing Zheng
- Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen Translational Medical Key Laboratory of Hepatobiliary and Pancreatic Tumor, Zhongshan Hospital Xiamen University, Xiamen, 361004, China
| | - Min Feng
- Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen Translational Medical Key Laboratory of Hepatobiliary and Pancreatic Tumor, Zhongshan Hospital Xiamen University, Xiamen, 361004, China
| | - Qiu Li
- Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen Translational Medical Key Laboratory of Hepatobiliary and Pancreatic Tumor, Zhongshan Hospital Xiamen University, Xiamen, 361004, China
| | - Hui Jiao
- Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen Translational Medical Key Laboratory of Hepatobiliary and Pancreatic Tumor, Zhongshan Hospital Xiamen University, Xiamen, 361004, China
| | - Xiaoqin Chi
- Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen Translational Medical Key Laboratory of Hepatobiliary and Pancreatic Tumor, Zhongshan Hospital Xiamen University, Xiamen, 361004, China
| | - Wenxiu Zhao
- Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen Translational Medical Key Laboratory of Hepatobiliary and Pancreatic Tumor, Zhongshan Hospital Xiamen University, Xiamen, 361004, China
| | - Sheng Zhang
- Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen Translational Medical Key Laboratory of Hepatobiliary and Pancreatic Tumor, Zhongshan Hospital Xiamen University, Xiamen, 361004, China
| | - Xiaomin Wang
- Department of Hepatobiliary Surgery, School of Clinical Medicine, Fujian Medical University, Fuzhou, Fujian, 350108, China; Fujian Provincial Key Laboratory of Chronic Liver Disease and Hepatocellular Carcinoma, Xiamen Translational Medical Key Laboratory of Hepatobiliary and Pancreatic Tumor, Zhongshan Hospital Xiamen University, Xiamen, 361004, China.
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18
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Functional analysis of Cullin 3 E3 ligases in tumorigenesis. Biochim Biophys Acta Rev Cancer 2017; 1869:11-28. [PMID: 29128526 DOI: 10.1016/j.bbcan.2017.11.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/06/2017] [Accepted: 11/06/2017] [Indexed: 12/14/2022]
Abstract
Cullin 3-RING ligases (CRL3) play pivotal roles in the regulation of various physiological and pathological processes, including neoplastic events. The substrate adaptors of CRL3 typically contain a BTB domain that mediates the interaction between Cullin 3 and target substrates to promote their ubiquitination and subsequent degradation. The biological implications of CRL3 adaptor proteins have been well described where they have been found to play a role as either an oncogene, tumor suppressor, or can mediate either of these effects in a context-dependent manner. Among the extensively studied CRL3-based E3 ligases, the role of the adaptor protein SPOP (speckle type BTB/POZ protein) in tumorigenesis appears to be tissue or cellular context dependent. Specifically, SPOP acts as a tumor suppressor via destabilizing downstream oncoproteins in many malignancies, especially in prostate cancer. However, SPOP has largely an oncogenic role in kidney cancer. Keap1, another well-characterized CRL3 adaptor protein, likely serves as a tumor suppressor within diverse malignancies, mainly due to its specific turnover of its downstream oncogenic substrate, NRF2 (nuclear factor erythroid 2-related factor 2). In accordance with the physiological role the various CRL3 adaptors exhibit, several pharmacological agents have been developed to disrupt its E3 ligase activity, therefore blocking its potential oncogenic activity to mitigate tumorigenesis.
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19
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Hamann BL, Blind RD. Nuclear phosphoinositide regulation of chromatin. J Cell Physiol 2017; 233:107-123. [PMID: 28256711 DOI: 10.1002/jcp.25886] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 03/01/2017] [Indexed: 12/26/2022]
Abstract
Phospholipid signaling has clear connections to a wide array of cellular processes, particularly in gene expression and in controlling the chromatin biology of cells. However, most of the work elucidating how phospholipid signaling pathways contribute to cellular physiology have studied cytoplasmic membranes, while relatively little attention has been paid to the role of phospholipid signaling in the nucleus. Recent work from several labs has shown that nuclear phospholipid signaling can have important roles that are specific to this cellular compartment. This review focuses on the nuclear phospholipid functions and the activities of phospholipid signaling enzymes that regulate metazoan chromatin and gene expression. In particular, we highlight the roles that nuclear phosphoinositides play in several nuclear-driven physiological processes, such as differentiation, proliferation, and gene expression. Taken together, the recent discovery of several specifically nuclear phospholipid functions could have dramatic impact on our understanding of the fundamental mechanisms that enable tight control of cellular physiology.
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Affiliation(s)
- Bree L Hamann
- Division of Diabetes Endocrinology and Metabolism, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Raymond D Blind
- Division of Diabetes Endocrinology and Metabolism, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee.,Departments of Medicine, Biochemistry and Pharmacology, Division of Diabetes Endocrinology and Metabolism, The Vanderbilt Diabetes Research and Training Center and the Vanderbilt-Ingram Cancer Center, Nashville, Tennessee
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20
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De Craene JO, Bertazzi DL, Bär S, Friant S. Phosphoinositides, Major Actors in Membrane Trafficking and Lipid Signaling Pathways. Int J Mol Sci 2017; 18:ijms18030634. [PMID: 28294977 PMCID: PMC5372647 DOI: 10.3390/ijms18030634] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 03/02/2017] [Accepted: 03/06/2017] [Indexed: 11/30/2022] Open
Abstract
Phosphoinositides are lipids involved in the vesicular transport of proteins and lipids between the different compartments of eukaryotic cells. They act by recruiting and/or activating effector proteins and thus are involved in regulating various cellular functions, such as vesicular budding, membrane fusion and cytoskeleton dynamics. Although detected in small concentrations in membranes, their role is essential to cell function, since imbalance in their concentrations is a hallmark of many cancers. Their synthesis involves phosphorylating/dephosphorylating positions D3, D4 and/or D5 of their inositol ring by specific lipid kinases and phosphatases. This process is tightly regulated and specific to the different intracellular membranes. Most enzymes involved in phosphoinositide synthesis are conserved between yeast and human, and their loss of function leads to severe diseases (cancer, myopathy, neuropathy and ciliopathy).
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Affiliation(s)
- Johan-Owen De Craene
- Department of Molecular and Cellular Genetics, Université de Strasbourg, CNRS, GMGM UMR 7156, F-67000 Strasbourg, France.
| | - Dimitri L Bertazzi
- Department of Molecular and Cellular Genetics, Université de Strasbourg, CNRS, GMGM UMR 7156, F-67000 Strasbourg, France.
| | - Séverine Bär
- Department of Molecular and Cellular Genetics, Université de Strasbourg, CNRS, GMGM UMR 7156, F-67000 Strasbourg, France.
| | - Sylvie Friant
- Department of Molecular and Cellular Genetics, Université de Strasbourg, CNRS, GMGM UMR 7156, F-67000 Strasbourg, France.
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21
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Klein S, Meng R, Montenarh M, Götz C. The Phosphorylation of PDX-1 by Protein Kinase CK2 Is Crucial for Its Stability. Pharmaceuticals (Basel) 2016; 10:ph10010002. [PMID: 28036027 PMCID: PMC5374406 DOI: 10.3390/ph10010002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 12/20/2016] [Accepted: 12/23/2016] [Indexed: 12/14/2022] Open
Abstract
The homeodomain protein PDX-1 is a critical regulator of pancreatic development and insulin production in pancreatic β-cells. We have recently shown that PDX-1 is a substrate of protein kinase CK2; a multifunctional protein kinase which is implicated in the regulation of various cellular aspects, such as differentiation, proliferation, and survival. The CK2 phosphorylation site of PDX-1 is located within the binding region of the E3 ubiquitin ligase adaptor protein PCIF1. To study the interaction between PDX-1 and PCIF1 we used immunofluorescence analysis, co-immunoprecipitation, GST-pull-down studies, and proximity ligation assay (PLA). For the analysis of the stability of PDX-1 we performed a cycloheximide chase. We used PDX-1 in its wild-type form as well as phosphomutants of the CK2 phosphorylation site. In pancreatic β-cells PDX-1 binds to PCIF1. The phosphorylation of PDX-1 by CK2 increases the ratio of PCIF1 bound to PDX-1. The stability of PDX-1 is extended in the absence of CK2 phosphorylation. Our results identified protein kinase CK2 as new important modulator of the stability of PDX-1.
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Affiliation(s)
- Sabrina Klein
- Medical Biochemistry and Molecular Biology, Saarland University, 66424 Homburg, Germany.
| | - Rui Meng
- Medical Biochemistry and Molecular Biology, Saarland University, 66424 Homburg, Germany.
- Cancer Center of Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, No. 156 Wujiadun, Hankou, Wuhan 430045, China.
| | - Mathias Montenarh
- Medical Biochemistry and Molecular Biology, Saarland University, 66424 Homburg, Germany.
| | - Claudia Götz
- Medical Biochemistry and Molecular Biology, Saarland University, 66424 Homburg, Germany.
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22
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Liu X, Sun G, Sun X. RNA interference-mediated silencing of speckle-type POZ protein promotes apoptosis of renal cell cancer cells. Onco Targets Ther 2016; 9:2393-402. [PMID: 27143934 PMCID: PMC4846068 DOI: 10.2147/ott.s91097] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
This study aimed to investigate the effects of silencing the speckle-type POZ protein (SPOP) gene on renal cell cancer (RCC) cells and to explore its possible mechanism. The A498 and ACHN RCC cells were transfected with small interference RNA (siRNA)-SPOP by lipofection methods. The silencing efficiency was monitored by quantitative real-time polymerase chain reaction and Western blot. The effects of SPOP silencing on cell apoptosis, cell viability, colony formation ability, cell migration ability, and chemosensitivity to Sorafenib were assessed by flow cytometry, an MTT assay, a colony formation assay, a trans-well migration assay, and a CCK-8 assay, respectively. Its effects on the expression of several cytokines were determined by a protein microarray. Relevant signaling pathways were also analyzed. Compared with the control group, the cell apoptosis rate was significantly higher; the cell viability, the colony formation, and migration ability were significantly decreased in the siRNA-SPOP group. The protein microarray screening showed that the expression of vascular endothelial growth factor receptor, matrix metallopeptidase-9, vascular cell adhesion molecule-1, and stromal cell-derived factor-1 in the siRNA group was significantly decreased and that the expression of granulocyte-macrophage colony-stimulating factor and E-cadherin was significantly increased (P<0.05). The relevant signaling pathways were the integrin-mediated cell surface interactions pathway and extracellular matrix organization signal pathway. SPOP gene silencing induced cell apoptosis, decreased cell viability, colony formation, and migration ability, and elevated the drug sensitivity in the RCC cells. A possible mechanism is that silencing SPOP induces the differential expression of E-cadherin, vascular endothelial growth factor receptor, matrix metallopeptidase-9, and vascular cell adhesion molecule, which are related to the integrin-mediated cell surface interactions and extracellular matrix organization signaling pathway.
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Affiliation(s)
- Xiaoxia Liu
- Department of Nephrology, Affiliated Hospital of Weifang Medical University, Weifang, People's Republic of China
| | - Guiling Sun
- Department of Nephrology, Affiliated Hospital of Weifang Medical University, Weifang, People's Republic of China
| | - Xiuju Sun
- Department of Nephrology, Affiliated Hospital of Weifang Medical University, Weifang, People's Republic of China
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23
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Zhu H, Ren S, Bitler BG, Aird KM, Tu Z, Skordalakes E, Zhu Y, Yan J, Sun Y, Zhang R. SPOP E3 Ubiquitin Ligase Adaptor Promotes Cellular Senescence by Degrading the SENP7 deSUMOylase. Cell Rep 2015; 13:1183-1193. [PMID: 26527005 DOI: 10.1016/j.celrep.2015.09.083] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 08/12/2015] [Accepted: 09/29/2015] [Indexed: 11/25/2022] Open
Abstract
The SPOP gene, which encodes an E3 ubiquitin ligase adaptor, is frequently mutated in a number of cancer types. However, the mechanisms by which SPOP functions as a tumor suppressor remain poorly understood. Here, we show that SPOP promotes senescence, an important tumor suppression mechanism, by targeting the SENP7 deSUMOylase for degradation. SPOP is upregulated during senescence. This correlates with ubiquitin-mediated degradation of SENP7, which promotes senescence by increasing HP1α sumoylation and the associated epigenetic gene silencing. Ectopic wild-type SPOP, but not its cancer-associated mutants, drives senescence. Conversely, SPOP knockdown overcomes senescence. These phenotypes correlate with ubiquitination and degradation of SENP7 and HP1α sumoylation, subcellular re-localization, and its associated gene silencing. Furthermore, SENP7 is expressed at higher levels in prostate tumor specimens with SPOP mutation (n = 13) compared to those with wild-type SPOP (n = 80). In summary, SPOP acts as a tumor suppressor by promoting senescence through degrading SENP7.
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Affiliation(s)
- Hengrui Zhu
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, PA 19104, USA
| | - Shancheng Ren
- Department of Urology, Shanghai Changhai Hospital, Second Military Medical University, Shanghai 200433, People's Republic of China
| | - Benjamin G Bitler
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, PA 19104, USA
| | - Katherine M Aird
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, PA 19104, USA
| | - Zhigang Tu
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, PA 19104, USA
| | - Emmanuel Skordalakes
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, PA 19104, USA
| | - Yasheng Zhu
- Department of Urology, Shanghai Changhai Hospital, Second Military Medical University, Shanghai 200433, People's Republic of China
| | - Jun Yan
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing, Jiangsu 210061, People's Republic of China
| | - Yinghao Sun
- Department of Urology, Shanghai Changhai Hospital, Second Military Medical University, Shanghai 200433, People's Republic of China.
| | - Rugang Zhang
- Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, PA 19104, USA.
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24
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Shin YJ, Park SK, Jung YJ, Kim YN, Kim KS, Park OK, Kwon SH, Jeon SH, Trinh LA, Fraser SE, Kee Y, Hwang BJ. Nanobody-targeted E3-ubiquitin ligase complex degrades nuclear proteins. Sci Rep 2015; 5:14269. [PMID: 26373678 PMCID: PMC4571616 DOI: 10.1038/srep14269] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 08/21/2015] [Indexed: 12/22/2022] Open
Abstract
Targeted protein degradation is a powerful tool in determining the function of specific proteins or protein complexes. We fused nanobodies to SPOP, an adaptor protein of the Cullin-RING E3 ubiquitin ligase complex, resulting in rapid ubiquitination and subsequent proteasome-dependent degradation of specific nuclear proteins in mammalian cells and zebrafish embryos. This approach is easily modifiable, as substrate specificity is conferred by an antibody domain that can be adapted to target virtually any protein.
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Affiliation(s)
- Yeong Ju Shin
- Department of Molecular Bioscience, College of Biomedical Science, Kangwon National University, Chunchon, 200-701, Republic of Korea
| | - Seung Kyun Park
- Department of Molecular Bioscience, College of Biomedical Science, Kangwon National University, Chunchon, 200-701, Republic of Korea
| | - Yoo Jung Jung
- Department of Systems Immunology, College of Biomedical Science, Kangwon National University, Chunchon, 200-701, Republic of Korea
| | - Ye Na Kim
- Department of Molecular Bioscience, College of Biomedical Science, Kangwon National University, Chunchon, 200-701, Republic of Korea
| | - Ki Sung Kim
- Department of Molecular Bioscience, College of Biomedical Science, Kangwon National University, Chunchon, 200-701, Republic of Korea
| | - Ok Kyu Park
- Korea Basic Science Institute Chuncheon Center, Chuncheon, 200-701, Republic of Korea
| | - Seung-Hae Kwon
- Korea Basic Science Institute Chuncheon Center, Chuncheon, 200-701, Republic of Korea
| | - Sung Ho Jeon
- Department of Life Science, Hallym University, Chuncheon, 200-702, Republic of Korea
| | - Le A Trinh
- Biological Sciences and Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Scott E Fraser
- Biological Sciences and Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
| | - Yun Kee
- Department of Systems Immunology, College of Biomedical Science, Kangwon National University, Chunchon, 200-701, Republic of Korea
| | - Byung Joon Hwang
- Department of Molecular Bioscience, College of Biomedical Science, Kangwon National University, Chunchon, 200-701, Republic of Korea
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25
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Zhou Z, Xu C, Chen P, Liu C, Pang S, Yao X, Zhang Q. Stability of HIB-Cul3 E3 ligase adaptor HIB Is Regulated by Self-degradation and Availability of Its Substrates. Sci Rep 2015; 5:12709. [PMID: 26263855 PMCID: PMC4533009 DOI: 10.1038/srep12709] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 07/06/2015] [Indexed: 12/29/2022] Open
Abstract
The HIB-Cul3 complex E3 ligase regulates physiological homeostasis through regulating its substrate stability and its activity can be modulated by changing HIB abundance. However, regulation of HIB remains elusive. Here we provide evidence that HIB is degraded through the proteasome by Cul3-mediated polyubiquitination in K48 manner in Drosophila. Strikingly, HIB is targeted for degradation by itself. We further identify that three degrons (52LKSS56T, 76LDEE80S and 117MESQ121R) and K185 and K198 of HIB are essential for its auto-degradation. Finally, we demonstrate that HIB-Cul3 substrates, Ci and Puc, can effectively protect HIB from HIB-Cul3-mediated degradation. Taken together, our study indicates that there is an exquisite equilibrium between the adaptor and targets to achieve the tight control of the HIB, which is essential for maintaining suitable Hh and JNK signaling. And the mechanism of adaptor self-degradation and reciprocal control of the abundance between adaptor and its substrates is also applied to BTB-Cul3 E3 ligase adaptor dKeap1, dDiablo and dKLHL18.
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Affiliation(s)
- Zizhang Zhou
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, 210061, China
| | - Congyu Xu
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, 210061, China
| | - Ping Chen
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, 210061, China
| | - Chen Liu
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, 210061, China
| | - Shu Pang
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, 210061, China
| | - Xia Yao
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, 210061, China
| | - Qing Zhang
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, 210061, China
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26
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Properties and Clinical Relevance of Speckle-Type POZ Protein in Human Colorectal Cancer. J Gastrointest Surg 2015; 19:1484-96. [PMID: 26022775 DOI: 10.1007/s11605-015-2767-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 01/30/2015] [Indexed: 01/31/2023]
Abstract
BACKGROUND The aims of this study are to evaluate the effect of Speckle-type POZ protein (SPOP) in colorectal cancer (CRC) patients and explore its significance in the prognosis. METHODS We used immunohistochemistry to detect the expression of SPOP in CRC. Moreover, this result was further confirmed at the protein and messenger RNA (mRNA) level in paired CRC specimens and matched adjacent noncancerous colon tissues by Western blotting and real-time quantitative PCR (qRT-PCR), respectively. Furthermore, we evaluate the effects of SPOP on CRC cell proliferation and migration in vitro. The Kaplan-Meier method and log-rank test were employed to compare the overall survival between SPOP low expression group and SPOP high expression group. Correlation of survival with clinicopathologic parameters, including SPOP level, was investigated with multivariate analyses. RESULTS We confirmed frequent SPOP downregulation in both mRNA (P = 0.0286) and protein (P = 0.004) levels in CRC tissues as compared to matched adjacent nontumorous tissues. Besides, the downregulated SPOP expression in CRC tissues was significantly correlated to poor differentiation (P = 0.013), distant metastasis (P = 0.003), gross type (P < 0.001), and high TNM stage (P = 0.002). Kaplan-Meier survival analysis showed that low SPOP expression exhibited a significant correlation with poor prognosis for CRC patients. Overexpression of SPOP in CRC cell lines significantly suppressed cell proliferation, migration, and clone formation. In contrast, SPOP knockdown dramatically promoted cell proliferation, migration, and clone formation in vitro. In addition, overexpression of SPOP increased E-cadherin and suppressed vimentin in HCT116 cells and silencing of SPOP reversed all these biomarkers. Furthermore, SPOP significantly downregulated MMP2 and MMP7 protein levels in HCT116 cell lines. CONCLUSION Our results suggest that SPOP plays a pivotal role in colorectal cancer (CRC) through mesenchymal-epithelial transition and MMPs, and it may be a potential therapeutic target in colorectal cancer.
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Bertazzi DL, De Craene JO, Bär S, Sanjuan-Vazquez M, Raess MA, Friant S. [Phosphoinositides: lipidic essential actors in the intracellular traffic]. Biol Aujourdhui 2015; 209:97-109. [PMID: 26115715 DOI: 10.1051/jbio/2015006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Indexed: 06/04/2023]
Abstract
Phosphoinositides (PPIn) are lipids involved in the vesicular transport of proteins between the different intracellular compartments. They act by recruiting and/or activating effector proteins and are thus involved in crucial cellular functions including vesicle budding, fusion and dynamics of membranes and regulation of the cytoskeleton. Although they are present in low concentrations in membranes, their activity is essential for cell survival and needs to be tightly controlled. Therefore, phosphatases and kinases specific of the various cellular membranes can phosphorylate/dephosphorylate their inositol ring on the positions D3, D4 and/or D5. The differential phosphorylation determines the intracellular localisation and the activity of the PPIn. Indeed, non-phosphorylated phosphatidylinositol (PtdIns) is the basic component of the PPIn and can be found in all eukaryotic cells at the cytoplasmic face of the ER, the Golgi, mitochondria and microsomes. It can get phosphorylated on position D4 to obtain PtdIns4P, a PPIn enriched in the Golgi compartment and involved in the maintenance of this organelle as well as anterograde and retrograde transport to and from the Golgi. PtdIns phosphorylation on position D3 results in PtdIns3P that is required for endosomal transport and multivesicular body (MVB) formation and sorting. These monophosphorylated PtdIns can be further phosphorylated to produce bisphophorylated PtdIns. Thus, PtdIns(4,5)P2, mainly produced by PtdIns4P phosphorylation, is enriched in the plasma membrane and involved in the regulation of actin cytoskeleton and endocytosis. PtdIns(3,5)P2, mainly produced by PtdIns3P phosphorylation, is enriched in late endosomes, MVBs and the lysosome/vacuole and plays a role in endosome to vacuole transport. PtdIns(3,4)P2 is absent in yeast, cells and mainly produced by PtdIns4P phosphorylation in human cells; PtdIns(3,4)P2 is localised in the plasma membrane and plays an important role as a second messenger by recruiting specific protein kinases (Akt and PDK1). Finally the triple phosphorylated PPIn, PtdIns(3,4,5)P3 also absent in yeast, is produced by the phosphorylation of PtdIns(3,4)P2 and localized at the plasma membrane of human cells where it binds proteins via their PH domain. Interaction partners include members of the Arf (ADP-ribosylation factors) family, PDK1 (Phosphoinositide Dependent Kinase 1) and Akt. Therefore this last PPIn is essential for the control of cell proliferation and its deregulation leads to the development of numerous cancers. In conclusion, the regulation of PPIn phosphorylation/dephosphorylation is complex and needs to be very precisely regulated. Indeed phosphatases and kinases allow the maintenance of the equilibrium between the different forms. PPIn play a crucial role in numerous cellular functions and a loss in their synthesis or regulation results in severe genetic diseases.
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Choi S, Thapa N, Tan X, Hedman AC, Anderson RA. PIP kinases define PI4,5P₂signaling specificity by association with effectors. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1851:711-23. [PMID: 25617736 PMCID: PMC4380618 DOI: 10.1016/j.bbalip.2015.01.009] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 01/14/2015] [Accepted: 01/16/2015] [Indexed: 12/21/2022]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI4,5P₂) is an essential lipid messenger with roles in all eukaryotes and most aspects of human physiology. By controlling the targeting and activity of its effectors, PI4,5P₂modulates processes, such as cell migration, vesicular trafficking, cellular morphogenesis, signaling and gene expression. In cells, PI4,5P₂has a much higher concentration than other phosphoinositide species and its total content is largely unchanged in response to extracellular stimuli. The discovery of a vast array of PI4,5P₂ binding proteins is consistent with data showing that the majority of cellular PI4,5P₂is sequestered. This supports a mechanism where PI4,5P₂functions as a localized and highly specific messenger. Further support of this mechanism comes from the de novo synthesis of PI4,5P₂which is often linked with PIP kinase interaction with PI4,5P₂effectors and is a mechanism to define specificity of PI4,5P₂signaling. The association of PI4,5P₂-generating enzymes with PI4,5P₂effectors regulate effector function both temporally and spatially in cells. In this review, the PI4,5P₂effectors whose functions are tightly regulated by associations with PI4,5P₂-generating enzymes will be discussed. This article is part of a Special Issue entitled Phosphoinositides.
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Affiliation(s)
- Suyong Choi
- Cellular and Molecular Biology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Narendra Thapa
- Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Xiaojun Tan
- Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Andrew C Hedman
- Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA
| | - Richard A Anderson
- Cellular and Molecular Biology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA; Molecular and Cellular Pharmacology Program, University of Wisconsin-Madison, School of Medicine and Public Health, 1300 University Avenue, Madison, WI 53706, USA.
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Ding D, Song T, Jun W, Tan Z, Fang J. Decreased expression of the SPOP gene is associated with poor prognosis in glioma. Int J Oncol 2014; 46:333-41. [PMID: 25351530 DOI: 10.3892/ijo.2014.2729] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Accepted: 10/03/2014] [Indexed: 11/05/2022] Open
Abstract
This study suggests that speckle-type POZ protein (SPOP) may be a tumor suppressor gene and its prognostic value in human glioma. Real-time quantitative RT-PCR (qRT‑PCR), western blotting, and immunohistochemical staining were used to examine SPOP expression in glioma tissues and normal brain (NB) tissues. The relationships between the SPOP expression levels, the clinicopathological factors, and patient survival were investigated. The molecular mechanisms of SPOP expression and its effects on cell viability, migration and invasion were also explored by MTT assay, wound-healing assays and Transwell assay. SPOP mRNA and protein levels were downregulated in glioma tissues compared to NB. Immunohistochemical staining results showed low expression in 62.2% (61/98) of glioma samples, while high expression in 75% (9/12) of NB samples, and the difference was statistically significant (P=0.014). In addition, decreased SPOP was associated disease progression in glioma samples, the expression level of SPOP was positively correlated with mean tumor diameter (MTD) (P=0.021) and the status of tumor grade and histological type (WHO I, II, III and IV) (P=0.032) in glioma patients. Additionally, the overall survival of patients with low SPOP expression was significantly worse than that of SPOP-high patients (P=0.001). In vitro overexpression of SPOP markedly inhibited cell viability, migration and invasion in vitro. These findings suggest that SPOP has potential use as novel biomarker of glioma and may serve as an independent predictive factor for prognosis of glioma patients.
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Affiliation(s)
- Dacheng Ding
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Tao Song
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Wu Jun
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Zeming Tan
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Jiasheng Fang
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
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Bulley SJ, Clarke JH, Droubi A, Giudici ML, Irvine RF. Exploring phosphatidylinositol 5-phosphate 4-kinase function. Adv Biol Regul 2014; 57:193-202. [PMID: 25311266 PMCID: PMC4359101 DOI: 10.1016/j.jbior.2014.09.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 09/01/2014] [Accepted: 09/02/2014] [Indexed: 11/30/2022]
Abstract
The family of phosphatidylinositol 5-phosphate 4-kinases (PI5P4Ks) is emerging from a comparative backwater in inositide signalling into the mainstream, as is their substrate, phosphatidylinositol 5-phosphate (PI5P). Here we review some of the key questions about the PI5P4Ks, their localisation, interaction, and regulation and also we summarise our current understanding of how PI5P is synthesised and what its cellular functions might be. Finally, some of the evidence for the involvement of PI5P4Ks in pathology is discussed.
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Affiliation(s)
- Simon J Bulley
- Department of Pharmacology, Tennis Court Road, Cambridge, CB2 1PD, UK
| | - Jonathan H Clarke
- Department of Pharmacology, Tennis Court Road, Cambridge, CB2 1PD, UK
| | - Alaa Droubi
- Department of Pharmacology, Tennis Court Road, Cambridge, CB2 1PD, UK
| | | | - Robin F Irvine
- Department of Pharmacology, Tennis Court Road, Cambridge, CB2 1PD, UK.
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Zeng C, Wang Y, Lu Q, Chen J, Zhang J, Liu T, Lv N, Luo S. SPOP suppresses tumorigenesis by regulating Hedgehog/Gli2 signaling pathway in gastric cancer. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2014; 33:75. [PMID: 25204354 PMCID: PMC4172815 DOI: 10.1186/s13046-014-0075-8] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 09/02/2014] [Indexed: 01/08/2023]
Abstract
Background Recent evidence suggests that aberrant activation of Hedgehog (Hh) signaling by Gli transcription factors is characteristic of a variety of aggressive human carcinomas including gastric cancer. Speckle-type POZ protein, SPOP, is an E3 ubiquitin ligase adaptor, and it is found to inhibit oncogenic signaling. However, the molecular mechanisms are largely unknown. Methods In this study, we characterized the expression of SPOP in 88 pairs of gastric cancer tissues and adjacent tissues by immunohistochemical staining and Western blotting. The relationship between SPOP expression and clinical pathologic factors was analyzed. Transfected gastric cancer cell lines were used in cell viability, wound healing and colony formation assays. The interaction of SPOP with Gli2 and other related apoptotic proteins was assessed by immunoprecipitation, Western blotting, real-time PCR and dual luciferase reporter assays. Intracellular interaction of SPOP and Gli2 was visualized by immunofluorescent staining in gastric cancer cells. Results Immunohistochemical staining of SPOP can be detected in gastric cancer tissues but much less than adjacent gastric tissues (P < 0.01). High SPOP expression is negatively correlated with lymph node metastasis, poor histological differentiation, and tumor malignancy according to TNM staging. In vitro experiments revealed that over-expression of SPOP prevented tumor cells from proliferation, migration and colony formation in gastric cancer cell lines. Likewise, repression of SPOP promoted cell viability, migration, proliferation, and attenuated apoptosis. Mechanistic studies revealed that increasing SPOP accelerated Gli2 degradation but regardless of Gli2 synthesis. Furthermore, cytoplasmic Gli2 decreased markedly along with the abundant expression of SPOP in MKN45 cells. Conclusions Our findings indicate that SPOP plays critical roles in suppressing gastric tumorigenesis through inhibiting Hh/Gli2 signaling pathway. It may provide an alternative strategy for developing therapeutic agents of gastric cancer in future.
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Mani RS. The emerging role of speckle-type POZ protein (SPOP) in cancer development. Drug Discov Today 2014; 19:1498-502. [PMID: 25058385 DOI: 10.1016/j.drudis.2014.07.009] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 07/15/2014] [Indexed: 11/24/2022]
Abstract
Speckle-type POZ (pox virus and zinc finger protein) protein (SPOP) is an E3 ubiquitin ligase adaptor protein that is frequently mutated in prostate and endometrial cancers. All the cancer-associated SPOP mutations reported to date are clustered in the meprin and TRAF (Tumor necrosis factor receptor-associated factor) homology (MATH) domain, presumably affecting substrate binding. SPOP mutations in prostate cancer are mutually exclusive with the ETS (Erythroblast transformation-specific) family gene rearrangements and define a distinct molecular subclass of prostate cancer. SPOP mutations contribute to prostate cancer development by altering the steady-state levels of key components in the androgen-signaling pathway.
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Affiliation(s)
- Ram-Shankar Mani
- Department of Pathology, UT Southwestern Medical Center, Dallas, TX, USA; Department of Urology, UT Southwestern Medical Center, Dallas, TX, USA.
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Huang CJ, Chen HY, Lin WY, Choo KB. Differential expression of speckled POZ protein, SPOP: putative regulation by miR-145. J Biosci 2014; 39:401-13. [PMID: 24845504 DOI: 10.1007/s12038-014-9432-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The speckle POZ protein, SPOP, is an adaptor of the Cul3-based ubiquitination process, and has been implicated in the carcinogenesis process. Despite recent elucidation of biological functions, regulation of SPOP gene expression has not been reported. In this study, the mRNA levels of the mouse SPOP (mSPOP) gene were first shown to vary noticeably in different tissues. However, the SPOP protein was detected in high abundance only in Purkinje cells of the cerebellum and seminiferous tubule of the testis, echoing previous reports of involvement of ubiquitination in neuron cells and in spermatogenesis. In other mouse tissues and human cancer cell lines analysed, only low SPOP protein levels were detected. The 3'-untranslated regions of both the mSPOP and human SPOP transcripts harbor a conserved putative miR-145 binding site (BS). In some tissues and cell lines, miR-145 and SPOP protein levels were in an inverse relationship suggesting miR-145 regulation. Luciferase assays of deletion and point mutation constructs of the miR-145 BS, and miR-145 induction by serum starvation that resulted in reduced endogenous SPOP levels provided further evidence that miR-145 is likely involved in post-transcriptional regulation of SPOP expression in selected tissues, and possibly with the participation of other miRNA species.
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Affiliation(s)
- Chiu-Jung Huang
- Department of Animal Science and 2Graduate Institute of Biotechnology, Chinese Culture University, Yang Ming Shan, Taipei, Taiwan 111
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Zuhlke KA, Johnson AM, Tomlins SA, Palanisamy N, Carpten JD, Lange EM, Isaacs WB, Cooney KA. Identification of a novel germline SPOP mutation in a family with hereditary prostate cancer. Prostate 2014; 74:983-90. [PMID: 24796539 PMCID: PMC4230298 DOI: 10.1002/pros.22818] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 04/11/2014] [Indexed: 11/12/2022]
Abstract
BACKGROUND Family history of prostate cancer is a well-recognized risk factor. Previous linkage studies have reported a putative prostate cancer susceptibility locus at chromosome 17q21-22. SPOP (Speckle-type POZ protein) maps to the 17q21-22 candidate linkage region and is one of the most frequently mutated genes in sporadic prostate cancers. METHODS We performed targeted next generation sequencing to analyze 2009 exons from 202 genes in a candidate linkage region on chromosome 17q21-22 using 94 unrelated familial prostate cancer cases from the University of Michigan Prostate Cancer Genetics Project (n=54) and Johns Hopkins University (n=40) including the exons and UTRs of SPOP. RESULTS We identified a novel SPOP missense mutation (N296I) in a man with prostate cancer diagnosed at age 43. This mutation completely segregates with prostate cancer affection status among the men in this family. The N296I mutation resides within the evolutionarily conserved Bric-a-brac, Tramtrack, Broad-complex (BTB) domain, involved in recruiting targets to Cul3 for degradation. Analysis of the prostate tumor from this individual verified the presence of heterozygous N296I as well as an ERG fusion. CONCLUSIONS We have discovered a novel mutation in SPOP that tracks with prostate cancer within a family and is predicted to be deleterious. Taken together, our results implicate SPOP as a candidate gene for hereditary prostate cancer.
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Affiliation(s)
- Kimberly A. Zuhlke
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Anna M. Johnson
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Scott A. Tomlins
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Nallasivam Palanisamy
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | | | - Ethan M. Lange
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - William B. Isaacs
- Department of Urology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Kathleen A. Cooney
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
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PIPKIIα is widely expressed in hematopoietic-derived cells and may play a role in the expression of alpha- and gamma-globins in K562 cells. Mol Cell Biochem 2014; 393:145-53. [DOI: 10.1007/s11010-014-2054-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 04/03/2014] [Indexed: 10/25/2022]
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Li G, Ci W, Karmakar S, Chen K, Dhar R, Fan Z, Guo Z, Zhang J, Ke Y, Wang L, Zhuang M, Hu S, Li X, Zhou L, Li X, Calabrese MF, Watson ER, Prasad SM, Rinker-Schaeffer C, Eggener SE, Stricker T, Tian Y, Schulman BA, Liu J, White KP. SPOP promotes tumorigenesis by acting as a key regulatory hub in kidney cancer. Cancer Cell 2014; 25:455-68. [PMID: 24656772 PMCID: PMC4443692 DOI: 10.1016/j.ccr.2014.02.007] [Citation(s) in RCA: 135] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 10/26/2013] [Accepted: 02/14/2014] [Indexed: 01/29/2023]
Abstract
Hypoxic stress and hypoxia-inducible factors (HIFs) play important roles in a wide range of tumors. We demonstrate that SPOP, which encodes an E3 ubiquitin ligase component, is a direct transcriptional target of HIFs in clear cell renal cell carcinoma (ccRCC). Furthermore, hypoxia results in cytoplasmic accumulation of SPOP, which is sufficient to induce tumorigenesis. This tumorigenic activity occurs through the ubiquitination and degradation of multiple regulators of cellular proliferation and apoptosis, including the tumor suppressor PTEN, ERK phosphatases, the proapoptotic molecule Daxx, and the Hedgehog pathway transcription factor Gli2. Knockdown of SPOP specifically kills ccRCC cells, indicating that it may be a promising therapeutic target. Collectively, our results indicate that SPOP serves as a regulatory hub to promote ccRCC tumorigenesis.
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Affiliation(s)
- Guoqiang Li
- Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Weimin Ci
- Laboratory of Disease Genomics and Individualized Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Subhradip Karmakar
- Institute for Genomics and Systems Biology, University of Chicago and Argonne National Laboratory, Chicago, IL 60637, USA; Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Ke Chen
- Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Ruby Dhar
- Institute for Genomics and Systems Biology, University of Chicago and Argonne National Laboratory, Chicago, IL 60637, USA; Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Zhixiang Fan
- Kunming Medical University, Kunming, Yunnan 650500, China
| | - Zhongqiang Guo
- Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China; Department of Urology, First Hospital of Peking University, Beijing 100034, China
| | - Jing Zhang
- Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yuwen Ke
- Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Lu Wang
- Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Min Zhuang
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Shengdi Hu
- Laboratory of Animal Research Center, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xuesong Li
- Department of Urology, First Hospital of Peking University, Beijing 100034, China
| | - Liqun Zhou
- Department of Urology, First Hospital of Peking University, Beijing 100034, China
| | - Xianghong Li
- Department of Pathology, Peking University Cancer Hospital, Beijing 100142, China
| | - Matthew F Calabrese
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Edmond R Watson
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Sandip M Prasad
- Section of Urology, Department of Surgery, University of Chicago, Chicago, IL 60637, USA
| | | | - Scott E Eggener
- Section of Urology, Department of Surgery, University of Chicago, Chicago, IL 60637, USA
| | - Thomas Stricker
- Institute for Genomics and Systems Biology, University of Chicago and Argonne National Laboratory, Chicago, IL 60637, USA; Department of Pathology, University of Chicago, Chicago, IL 60637, USA
| | - Yong Tian
- Laboratory of Animal Research Center, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Brenda A Schulman
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Howard Hughes Medical Institute, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Jiang Liu
- Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.
| | - Kevin P White
- Institute for Genomics and Systems Biology, University of Chicago and Argonne National Laboratory, Chicago, IL 60637, USA; Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA; Section on Genetic Medicine, Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
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Viaud J, Boal F, Tronchère H, Gaits-Iacovoni F, Payrastre B. Phosphatidylinositol 5-phosphate: A nuclear stress lipid and a tuner of membranes and cytoskeleton dynamics. Bioessays 2013; 36:260-72. [DOI: 10.1002/bies.201300132] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Julien Viaud
- Inserm U1048; I2MC and Université Paul Sabatier; Toulouse France
| | - Frédéric Boal
- Inserm U1048; I2MC and Université Paul Sabatier; Toulouse France
| | - Hélène Tronchère
- Inserm U1048; I2MC and Université Paul Sabatier; Toulouse France
| | | | - Bernard Payrastre
- Inserm U1048; I2MC and Université Paul Sabatier; Toulouse France
- CHU de Toulouse; Laboratoire d'Hématologie; Toulouse France
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Evolutionarily conserved structural changes in phosphatidylinositol 5-phosphate 4-kinase (PI5P4K) isoforms are responsible for differences in enzyme activity and localization. Biochem J 2013; 454:49-57. [PMID: 23758345 PMCID: PMC3749867 DOI: 10.1042/bj20130488] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Mammals have genes coding for three PI5P4Ks (PtdIns5P 4-kinases), and these have different cellular localizations, tissue distributions and lipid kinase activities. We describe in the present paper a detailed molecular exploration of human PI5P4Ks α, β and γ, as well as their fly and worm homologues, to understand how and why these differences came to be. The intrinsic ATPase activities of the three isoforms are very similar, and we show that differences in their G-loop regions can account for much of their wide differences in lipid kinase activity. We have also undertaken an extensive in silico evolutionary study of the PI5P4K family, and show experimentally that the single PI5P4K homologues from Caenorhabditis elegans and Drosophila melanogaster are as widely different in activity as the most divergent mammalian isoforms. Finally we show that the close association of PI5P4Ks α and γ is a true heterodimerization, and not a higher oligomer association of homodimers. We reveal that structural modelling is consistent with this and with the apparently random heterodimerization that we had earlier observed between PI5P4Kα and PI5P4Kβ [Wang, Bond, Letcher, Richardson, Lilley, Irvine and Clarke (2010), Biochem. J. 430, 215–221]. Overall the molecular diversity of mammalian PI5P4Ks explains much of their properties and behaviour, but their physiological functionality remains elusive.
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Keune WJ, Sims AH, Jones DR, Bultsma Y, Lynch JT, Jirström K, Landberg G, Divecha N. Low PIP4K2B expression in human breast tumors correlates with reduced patient survival: A role for PIP4K2B in the regulation of E-cadherin expression. Cancer Res 2013; 73:6913-25. [PMID: 24127122 DOI: 10.1158/0008-5472.can-13-0424] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Phosphatidylinositol-5-phosphate (PtdIns5P) 4-kinase β (PIP4K2B) directly regulates the levels of two important phosphoinositide second messengers, PtdIns5P and phosphatidylinositol-(4,5)-bisphosphate [PtdIns(4,5)P2]. PIP4K2B has been linked to the regulation of gene transcription, to TP53 and AKT activation, and to the regulation of cellular reactive oxygen accumulation. However, its role in human tumor development and on patient survival is not known. Here, we have interrogated the expression of PIP4K2B in a cohort (489) of patients with breast tumor using immunohistochemical staining and by a meta-analysis of gene expression profiles from 2,999 breast tumors, both with associated clinical outcome data. Low PIP4K2B expression was associated with increased tumor size, high Nottingham histological grade, Ki67 expression, and distant metastasis, whereas high PIP4K2B expression strongly associated with ERBB2 expression. Kaplan-Meier curves showed that both high and low PIP4K2B expression correlated with poorer patient survival compared with intermediate expression. In normal (MCF10A) and tumor (MCF7) breast epithelial cell lines, mimicking low PIP4K2B expression, using short hairpin RNA interference-mediated knockdown, led to a decrease in the transcription and expression of the tumor suppressor protein E-cadherin (CDH1). In MCF10A cells, knockdown of PIP4K2B enhanced TGF-β-induced epithelial to mesenchymal transition (EMT), a process required during the development of metastasis. Analysis of gene expression datasets confirmed the association between low PIP4K2B and low CDH1expression. Decreased CDH1 expression and enhancement of TGF-β-induced EMT by reduced PIP4K2B expression might, in part, explain the association between low PIP4K2B expression and poor patient survival.
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Affiliation(s)
- Willem-Jan Keune
- Authors' Affiliations: The CRUK Inositide Laboratory; Breakthrough Breast Cancer Research Unit; Leukaemia Biology, Inositide Group Cancer Research UK Manchester Institute, The University of Manchester, Manchester; Applied Bioinformatics of Cancer, University of Edinburgh Cancer Research UK Centre, Edinburgh, United Kingdom; and Center for Molecular Pathology, Department of Laboratory Medicine, Lund University, Skåne University Hospital Malmö, Malmö, Sweden
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Nuclear phosphatidylinositol-5-phosphate regulates ING2 stability at discrete chromatin targets in response to DNA damage. Sci Rep 2013; 3:2137. [PMID: 23823870 PMCID: PMC3705588 DOI: 10.1038/srep02137] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 06/14/2013] [Indexed: 01/25/2023] Open
Abstract
ING2 (inhibitor of growth family member 2) is a component of a chromatin-regulatory complex that represses gene expression and is implicated in cellular processes that promote tumor suppression. However, few direct genomic targets of ING2 have been identified and the mechanism(s) by which ING2 selectively regulates genes remains unknown. Here we provide evidence that direct association of ING2 with the nuclear phosphoinositide phosphatidylinositol-5-phosphate (PtdIns(5)P) regulates a subset of ING2 targets in response to DNA damage. At these target genes, the binding event between ING2 and PtdIns(5)P is required for ING2 promoter occupancy and ING2-associated gene repression. Moreover, depletion of PtdIns(5)P attenuates ING2-mediated regulation of these targets in the presence of DNA damage. Taken together, these findings support a model in which PtdIns(5)P functions as a sub-nuclear trafficking factor that stabilizes ING2 at discrete genomic sites.
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Genschik P, Sumara I, Lechner E. The emerging family of CULLIN3-RING ubiquitin ligases (CRL3s): cellular functions and disease implications. EMBO J 2013; 32:2307-20. [PMID: 23912815 DOI: 10.1038/emboj.2013.173] [Citation(s) in RCA: 203] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 07/12/2013] [Indexed: 01/07/2023] Open
Abstract
Protein ubiquitylation is a post-translational modification that controls all aspects of eukaryotic cell functionality, and its defective regulation is manifested in various human diseases. The ubiquitylation process requires a set of enzymes, of which the ubiquitin ligases (E3s) are the substrate recognition components. Modular CULLIN-RING ubiquitin ligases (CRLs) are the most prevalent class of E3s, comprising hundreds of distinct CRL complexes with the potential to recruit as many and even more protein substrates. Best understood at both structural and functional levels are CRL1 or SCF (SKP1/CUL1/F-box protein) complexes, representing the founding member of this class of multimeric E3s. Another CRL subfamily, called CRL3, is composed of the molecular scaffold CULLIN3 and the RING protein RBX1, in combination with one of numerous BTB domain proteins acting as substrate adaptors. Recent work has firmly established CRL3s as major regulators of different cellular and developmental processes as well as stress responses in both metazoans and higher plants. In humans, functional alterations of CRL3s have been associated with various pathologies, including metabolic disorders, muscle, and nerve degeneration, as well as cancer. In this review, we summarize recent discoveries on the function of CRL3s in both metazoans and plants, and discuss their mode of regulation and specificities.
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Affiliation(s)
- Pascal Genschik
- Unité Propre de Recherche 2357, Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire des Plantes, Conventionné avec l'Université de Strasbourg, Strasbourg, France.
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Shisheva A. PtdIns5P: news and views of its appearance, disappearance and deeds. Arch Biochem Biophys 2013; 538:171-80. [PMID: 23916588 DOI: 10.1016/j.abb.2013.07.023] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 07/22/2013] [Indexed: 12/24/2022]
Abstract
Accumulated evidence indicates that PtdIns5P, one of the seven phosphoinositides, found now to be constitutively present in yeast, plants and metazoa, serves as a signaling molecule to modulate pleiotropic cellular functions in both the nucleus and the cytoplasm. The enzymatic routes in biogenesis of basal PtdIns5P have remained incompletely understood. The role for candidate kinase PIKfyve that is principally involved in PtdIns(3,5)P2 production, has been questioned. In this review article we scrutinize the past obstacles that prevented the definitive implication of PIKfyve in PtdIns5P biosynthesis from PtdIns and focus on the recent pharmacological and genetic advancements that now make this conclusion well supported. We further summarize our current knowledge of the diverse stimuli modulating PtdIns5P levels, binding partners and regulated cellular process, with particular reference to the available mechanistic insights for the relevant signaling pathways.
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Affiliation(s)
- Assia Shisheva
- Department of Physiology, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI 48201, United States.
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Metzger T, Kleiss C, Sumara I. CUL3 and protein kinases: insights from PLK1/KLHL22 interaction. Cell Cycle 2013; 12:2291-6. [PMID: 24067371 PMCID: PMC3755079 DOI: 10.4161/cc.25369] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 06/11/2013] [Indexed: 12/12/2022] Open
Abstract
Posttranslational mechanisms drive fidelity of cellular processes. Phosphorylation and ubiquitination of substrates represent very common, covalent, posttranslational modifications and are often co-regulated. Phosphorylation may play a critical role both by directly regulating E3-ubiquitin ligases and/or by ensuring specificity of the ubiquitination substrate. Importantly, many kinases are not only critical regulatory components of these pathways but also represent themselves the direct ubiquitination substrates. Recent data suggest the role of CUL3-based ligases in both proteolytic and non-proteolytic regulation of protein kinases. Our own recent study identified the mitotic kinase PLK1 as a direct target of the CUL3 E3-ligase complex containing BTB-KELCH adaptor protein KLHL22. (1) In this study, we aim at gaining mechanistic insights into CUL3-mediated regulation of the substrates, in particular protein kinases, by analyzing mechanisms of interaction between KLHL22 and PLK1. We find that kinase activity of PLK1 is redundant for its targeting for CUL3-ubiquitination. Moreover, CUL3/KLHL22 may contact 2 distinct motifs within PLK1 protein, consistent with the bivalent mode of substrate targeting found in other CUL3-based complexes. We discuss these findings in the context of the existing knowledge on other protein kinases and substrates targeted by CUL3-based E3-ligases.
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Affiliation(s)
- Thibaud Metzger
- Institute of Genetics and Molecular and Cellular Biology (IGBMC); Illkirch, France
| | - Charlotte Kleiss
- Institute of Genetics and Molecular and Cellular Biology (IGBMC); Illkirch, France
| | - Izabela Sumara
- Institute of Genetics and Molecular and Cellular Biology (IGBMC); Illkirch, France
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Abstract
Phosphoinositides (PIs) make up only a small fraction of cellular phospholipids, yet they control almost all aspects of a cell's life and death. These lipids gained tremendous research interest as plasma membrane signaling molecules when discovered in the 1970s and 1980s. Research in the last 15 years has added a wide range of biological processes regulated by PIs, turning these lipids into one of the most universal signaling entities in eukaryotic cells. PIs control organelle biology by regulating vesicular trafficking, but they also modulate lipid distribution and metabolism via their close relationship with lipid transfer proteins. PIs regulate ion channels, pumps, and transporters and control both endocytic and exocytic processes. The nuclear phosphoinositides have grown from being an epiphenomenon to a research area of its own. As expected from such pleiotropic regulators, derangements of phosphoinositide metabolism are responsible for a number of human diseases ranging from rare genetic disorders to the most common ones such as cancer, obesity, and diabetes. Moreover, it is increasingly evident that a number of infectious agents hijack the PI regulatory systems of host cells for their intracellular movements, replication, and assembly. As a result, PI converting enzymes began to be noticed by pharmaceutical companies as potential therapeutic targets. This review is an attempt to give an overview of this enormous research field focusing on major developments in diverse areas of basic science linked to cellular physiology and disease.
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Affiliation(s)
- Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Prostate cancer-associated mutations in speckle-type POZ protein (SPOP) regulate steroid receptor coactivator 3 protein turnover. Proc Natl Acad Sci U S A 2013; 110:6997-7002. [PMID: 23559371 DOI: 10.1073/pnas.1304502110] [Citation(s) in RCA: 185] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The p160 steroid receptor coactivators (SRCs) SRC-1, SRC-2 [nuclear receptor coactivator (NCOA)2], and SRC-3 [amplified in breast cancer 1 (AIB1)/NCOA3] are key pleiotropic "master regulators" of transcription factor activity necessary for cancer cell proliferation, survival, metabolism, and metastasis. SRC overexpression and overactivation occur in numerous human cancers and are associated with poor clinical outcomes and resistance to therapy. In prostate cancer (PC), the p160 SRCs play critical roles in androgen receptor transcriptional activity, cell proliferation, and resistance to androgen deprivation therapy. We recently demonstrated that the E3 ubiquitin ligase adaptor speckle-type poxvirus and zinc finger (POZ) domain protein (SPOP) interacts directly with SRC-3 and promotes its cullin 3-dependent ubiquitination and proteolysis in breast cancer, thus functioning as a potential tumor suppressor. Interestingly, somatic heterozygous missense mutations in the SPOP substrate-binding cleft recently were identified in up to 15% of human PCs (making SPOP the gene most commonly affected by nonsynonymous point mutations in PC), but their contribution to PC pathophysiology remains unknown. We now report that PC-associated SPOP mutants cannot interact with SRC-3 protein or promote its ubiquitination and degradation. Our data suggest that wild-type SPOP plays a critical tumor suppressor role in PC cells, promoting the turnover of SRC-3 protein and suppressing androgen receptor transcriptional activity. This tumor suppressor effect is abrogated by the PC-associated SPOP mutations. These studies provide a possible explanation for the role of SPOP mutations in PC, and highlight the potential of SRC-3 as a therapeutic target in PC.
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Errington WJ, Khan MQ, Bueler SA, Rubinstein JL, Chakrabartty A, Privé GG. Adaptor protein self-assembly drives the control of a cullin-RING ubiquitin ligase. Structure 2012; 20:1141-53. [PMID: 22632832 DOI: 10.1016/j.str.2012.04.009] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 04/16/2012] [Accepted: 04/19/2012] [Indexed: 01/29/2023]
Abstract
The E3 ligases recruit substrate proteins for targeted ubiquitylation. Recent insights into the mechanisms of ubiquitylation demonstrate that E3 ligases can possess active regulatory properties beyond those of a simple assembly scaffold. Here, we describe the dimeric structure of the E3 ligase adaptor protein SPOP (speckle-type POZ protein) in complex with the N-terminal domain of Cul3 at 2.4 Å resolution. We find that SPOP forms large oligomers that can form heteromeric species with the closely related paralog SPOPL. In combination, SPOP and SPOPL (SPOP-like) form a molecular rheostat that can fine-tune E3 ubiquitin ligase activity by affecting the oligomeric state of the E3 complex. We propose that adaptor protein self-assembly provides a graded level of regulation of the SPOP/Cul3 E3 ligase toward its multiple protein substrates.
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Affiliation(s)
- Wesley J Errington
- Department of Biochemistry, University of Toronto, 1 Kings College Circle, Toronto, Ontario M5S 1A8, Canada
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The emerging role of PtdIns5P: another signalling phosphoinositide takes its place. Biochem Soc Trans 2012; 40:257-61. [PMID: 22260701 DOI: 10.1042/bst20110617] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Of the seven phosphoinositides, PtdIns5P remains the most enigmatic. However, recent research has begun to elucidate its physiological functions. It is now clear that PtdIns5P is found in several distinct subcellular locations, and the identification of a number of PtdIns5P-binding proteins points to its involvement in a variety of key processes, including signal transduction, membrane trafficking and regulation of gene expression. Although the mechanisms that control its turnover are not yet fully understood, the existence of multiple pathways for PtdIns5P regulation is consistent with this emerging versatility.
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Abstract
Phosphatidylinositol 4,5-bisphosphate (PIP(2)) is a membrane bound lipid molecule with capabilities to affect a wide array of signaling pathways to regulate very different cellular processes. PIP(2) is used as a precursor to generate the second messengers PIP(3), DAG and IP(3), indispensable molecules for signaling events generated by membrane receptors. However, PIP(2) can also directly regulate a vast array of proteins and is emerging as a crucial messenger with the potential to distinctly modulate biological processes critical for both normal and pathogenic cell physiology. PIP(2) directly associates with effector proteins via unique phosphoinositide binding domains, altering their localization and/or enzymatic activity. The spatial and temporal generation of PIP(2) synthesized by the phosphatidylinositol phosphate kinases (PIPKs) tightly regulates the activation of receptor signaling pathways, endocytosis and vesicle trafficking, cell polarity, focal adhesion dynamics, actin assembly and 3' mRNA processing. Here we discuss our current understanding of PIPKs in the regulation of cellular processes from the plasma membrane to the nucleus.
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Abstract
Phosphoinositides (PIs) are minor components of cellular membranes that play critical regulatory roles in several intracellular functions. This chapter describes the main enzymes regulating the turnover of each of the seven PIs in mammalian cells and introduces to some of their intracellular functions and to some evidences of their involvement in human diseases. Due to the complex interrelation between the distinct PIs and the plethora of functions that they can regulate inside a cell, this chapter is not meant to be a comprehensive coverage of all aspects of PI signalling but rather an introduction to this complex signalling field. For more details of their regulation/functions and extensive description of their intracellular roles, more detailed reviews are suggested on each single topic.
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Martelli AM, Ognibene A, Buontempo F, Fini M, Bressanin D, Goto K, McCubrey JA, Cocco L, Evangelisti C. Nuclear phosphoinositides and their roles in cell biology and disease. Crit Rev Biochem Mol Biol 2011; 46:436-57. [DOI: 10.3109/10409238.2011.609530] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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