1
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Singh R, Kundu P, Mishra VK, Singh BK, Bhattacharyya S, Das AK. Crystal structure of FadA2 thiolase from Mycobacterium tuberculosis and prediction of its substrate specificity and membrane-anchoring properties. FEBS J 2023; 290:3997-4022. [PMID: 37026388 DOI: 10.1111/febs.16792] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 03/17/2023] [Accepted: 04/05/2023] [Indexed: 04/08/2023]
Abstract
Tuberculosis (TB) is one of the leading causes of human death caused by Mycobacterium tuberculosis (Mtb). Mtb can enter into a long-lasting persistence where it can utilize fatty acids as the carbon source. Hence, fatty acid metabolism pathway enzymes are considered promising and pertinent mycobacterial drug targets. FadA2 (thiolase) is one of the enzymes involved in Mtb's fatty acid metabolism pathway. FadA2 deletion construct (ΔL136-S150) was designed to produce soluble protein. The crystal structure of FadA2 (ΔL136-S150) at 2.9 Å resolution was solved and analysed for membrane-anchoring region. The four catalytic residues of FadA2 are Cys99, His341, His390 and Cys427, and they belong to four loops with characteristic sequence motifs, i.e., CxT, HEAF, GHP and CxA. FadA2 is the only thiolase of Mtb which belongs to the CHH category containing the HEAF motif. Analysing the substrate-binding channel, it has been suggested that FadA2 is involved in the β-oxidation pathway, i.e., the degradative pathway, as the long-chain fatty acid can be accommodated in the channel. The catalysed reaction is favoured by the presence of two oxyanion holes, i.e., OAH1 and OAH2. OAH1 formation is unique in FadA2, formed by the NE2 of His390 present in the GHP motif and NE2 of His341 present in the HEAF motif, whereas OAH2 formation is similar to CNH category thiolase. Sequence and structural comparison with the human trifunctional enzyme (HsTFE-β) suggests the membrane-anchoring region in FadA2. Molecular dynamics simulations of FadA2 with a membrane containing POPE lipid were conducted to understand the role of a long insertion sequence of FadA2 in membrane anchoring.
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Affiliation(s)
- Rashika Singh
- Department of Biotechnology, Indian Institute of Technology Kharagpur, India
| | - Prasun Kundu
- Department of Biotechnology, Indian Institute of Technology Kharagpur, India
| | | | - Bina Kumari Singh
- School of Bioscience, Indian Institute of Technology Kharagpur, India
| | - Sudipta Bhattacharyya
- Department of Bioscience & Bioengineering, Indian Institute of Technology Jodhpur, India
| | - Amit Kumar Das
- Department of Biotechnology, Indian Institute of Technology Kharagpur, India
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2
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Grzymajlo K, El Hafny-Rahbi B, Kieda C. Tumour suppressor PTEN activity is differentially inducible by myo-inositol phosphates. J Cell Mol Med 2023; 27:879-890. [PMID: 36852461 PMCID: PMC10002956 DOI: 10.1111/jcmm.17699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 02/03/2023] [Accepted: 02/10/2023] [Indexed: 03/01/2023] Open
Abstract
Tumour evolution and efficacy of treatments are controlled by the microenvironment, the composition of which is primarily dependent on the angiogenic reaction to hypoxic stress. Tumour angiogenesis normalization is a challenge for adjuvant therapy strategies to chemo-, radio- and immunotherapeutics. Myo-inositol trispyrophosphate (ITPP) appears to provide the means to alleviate hypoxia in the tumour site by a double molecular mechanism. First, it modifies the properties of red blood cells (RBC) to release oxygen (O2 ) in the hypoxic sites more easily, leading to a rapid and stable increase in the partial pressure of oxygen (pO2 ). And second, it activates the endothelial phosphatase and tensin homologue deleted on Chromosome 10 (PTEN). The hypothesis that stable normalization of the vascular system is due to the PTEN, a tumour suppressor and phosphatase which controls the proper angiogenic reaction was ascertained. Here, by direct biochemical measurements of PTEN competitive activity in relation to PIP2 production, we show that the kinetics are complex in terms of the activation/inhibition effects of ITPP with an inverted consequence towards the kinase PI3K. The use of the surface plasmon resonance (SPR) technique allowed us to demonstrate that PTEN binds inositol derivatives differently but weakly. This method permitted us to reveal that PTEN is highly sensitive to the local concentration conditions, especially that ITPP increases the PTEN activity towards PIP3, and importantly, that PTEN affinity for ITPP is considerably increased by the presence of PIP3, as occurs in vivo. Our approach demonstrates the validity of using ITPP to activate PTEN for stable vessel normalization strategies.
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Affiliation(s)
- Krzysztof Grzymajlo
- Department of Biochemistry and Molecular Biology, Faculty of Veterinary Medicine, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
| | | | - Claudine Kieda
- Centre for Molecular Biophysics UPR 4301 CNRS, Orleans, France.,Military Institute of Medicine, Laboratory of Molecular Oncology and Innovative Therapies, Warsaw, Poland
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3
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Srinivasan S, Vanni S. Computational Approaches to Investigate and Design Lipid-binding Domains for Membrane Biosensing. Chimia (Aarau) 2021; 75:1031-1036. [PMID: 34920773 DOI: 10.2533/chimia.2021.1031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Association of proteins with cellular membranes is critical for signaling and membrane trafficking processes. Many peripheral lipid-binding domains have been identified in the last few decades and have been investigated for their specific lipid-sensing properties using traditional in vivo and in vitro studies. However, several knowledge gaps remain owing to intrinsic limitations of these methodologies. Thus, novel approaches are necessary to further our understanding in lipid-protein biology. This review briefly discusses lipid-binding domains that act as specific lipid biosensors and provides a broad perspective on the computational approaches such as molecular dynamics (MD) simulations and machine learning (ML)-based techniques that can be used to study protein-membrane interactions. We also highlight the need for de novo design of proteins that elicit specific lipid-binding properties.
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Affiliation(s)
| | - Stefano Vanni
- Department of Biology, University of Fribourg, Switzerland;,
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4
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Akbarzadeh M, Mihanfar A, Akbarzadeh S, Yousefi B, Majidinia M. Crosstalk between miRNA and PI3K/AKT/mTOR signaling pathway in cancer. Life Sci 2021; 285:119984. [PMID: 34592229 DOI: 10.1016/j.lfs.2021.119984] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 09/09/2021] [Accepted: 09/19/2021] [Indexed: 01/07/2023]
Abstract
Phosphoinositide-3 kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway is one of the most important proliferative signaling pathways with critical undeniable function in various aspects of cancer initiation/progression, including proliferation, apoptosis, metastasis, angiogenesis, and drug resistance. On the other hand, numerous genetic alterations in the key genes involved in the PI3K/AKT/mTOR signaling pathway have been identified in multiple solid and hematological tumors. In addition, accumulating recent evidences have demonstrated a reciprocal interaction between this signaling pathway and microRNAs, a large group of small non-coding RNAs. Therefore, in this review, it was attempted to discuss about the interaction between key components of PI3K/AKT/mTOR signaling pathway with various miRNAs and their importance in cancer biology.
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Affiliation(s)
- Maryam Akbarzadeh
- Department of biochemistry, Urmia University of Medical Sciences, Urmia, Iran
| | - Ainaz Mihanfar
- Department of biochemistry, Urmia University of Medical Sciences, Urmia, Iran
| | - Shabnam Akbarzadeh
- Department of Physical Education and Sport Medicine, University of Tabriz, Tabriz, Iran
| | - Bahman Yousefi
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Maryam Majidinia
- Solid Tumor Research Center, Urmia University of Medical Sciences, Urmia, Iran.
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5
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Larsen AH, Sansom MSP. Binding of Ca 2+-independent C2 domains to lipid membranes: A multi-scale molecular dynamics study. Structure 2021; 29:1200-1213.e2. [PMID: 34081910 PMCID: PMC8507603 DOI: 10.1016/j.str.2021.05.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 03/26/2021] [Accepted: 05/14/2021] [Indexed: 01/17/2023]
Abstract
C2 domains facilitate protein interactions with lipid bilayers in either a Ca2+-dependent or -independent manner. We used molecular dynamics (MD) simulations to explore six Ca2+-independent C2 domains, from KIBRA, PI3KC2α, RIM2, PTEN, SHIP2, and Smurf2. In coarse-grained MD simulations these C2 domains formed transient interactions with zwitterionic bilayers, compared with longer-lived interactions with anionic bilayers containing phosphatidylinositol bisphosphate (PIP2). Type I C2 domains bound non-canonically via the front, back, or side of the β sandwich, whereas type II C2 domains bound canonically, via the top loops. C2 domains interacted strongly with membranes containing PIP2, causing bound anionic lipids to cluster around the protein. Binding modes were refined via atomistic simulations. For PTEN and SHIP2, CG simulations of their phosphatase plus C2 domains with PIP2-containing bilayers were also performed, and the roles of the two domains in membrane localization compared. These studies establish a simulation protocol for membrane-recognition proteins. Binding of Ca2+-independent C2 domains to membranes was explored by MD simulation C2 domains from KIBRA, PI3KC2α, RIM2, PTEN, SHIP2, and Smurf2 were compared C2 domains formed longer-lived interactions with lipid bilayers containing PIP2 For PTEN and SHIP2, simulations of their phosphatase plus C2 domains were performed
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Affiliation(s)
- Andreas Haahr Larsen
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
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6
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Jang H, Smith IN, Eng C, Nussinov R. The mechanism of full activation of tumor suppressor PTEN at the phosphoinositide-enriched membrane. iScience 2021; 24:102438. [PMID: 34113810 PMCID: PMC8169795 DOI: 10.1016/j.isci.2021.102438] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 03/15/2021] [Accepted: 04/12/2021] [Indexed: 12/13/2022] Open
Abstract
Tumor suppressor PTEN, the second most highly mutated protein in cancer, dephosphorylates signaling lipid PIP3 produced by PI3Ks. Excess PIP3 promotes cell proliferation. The mechanism at the membrane of this pivotal phosphatase is unknown hindering drug discovery. Exploiting explicit solvent simulations, we tracked full-length PTEN trafficking from the cytosol to the membrane. We observed its interaction with membranes composed of zwitterionic phosphatidylcholine, anionic phosphatidylserine, and phosphoinositides, including signaling lipids PIP2 and PIP3. We tracked its moving away from the zwitterionic and getting absorbed onto anionic membrane that harbors PIP3. We followed it localizing on microdomains enriched in signaling lipids, as PI3K does, and observed PIP3 allosterically unfolding the N-terminal PIP2 binding domain, positioning it favorably for the polybasic motif interaction with PIP2. Finally, we determined PTEN catalytic action at the membrane, all in line with experimental observations, deciphering the mechanisms of how PTEN anchors to the membrane and restrains cancer. PTEN localizes on membrane microdomains enriched in phosphoinositides, as PI3K does Full PTEN activation requires both signaling lipids, PIP2 and PIP3 Strong salt bridge interactions sustain stable PTEN membrane localization Substrate-induced P loop conformational change implicates PTEN catalytic activity
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Affiliation(s)
- Hyunbum Jang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Laboratory of Cancer Immunometabolism, National Cancer Institute, Frederick, MD 21702, USA
| | - Iris Nira Smith
- Genomic Medicine Institute, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Charis Eng
- Genomic Medicine Institute, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA.,Center for Personalized Genetic Healthcare, Cleveland Clinic Community Care and Population Health, Cleveland, OH 44195, USA.,Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.,Germline High Risk Cancer Focus Group, Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Ruth Nussinov
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Laboratory of Cancer Immunometabolism, National Cancer Institute, Frederick, MD 21702, USA.,Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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7
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Hicks A, Escobar CA, Cross TA, Zhou HX. Fuzzy Association of an Intrinsically Disordered Protein with Acidic Membranes. JACS AU 2021; 1:66-78. [PMID: 33554215 PMCID: PMC7851954 DOI: 10.1021/jacsau.0c00039] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Indexed: 05/03/2023]
Abstract
Many physiological and pathophysiological processes, including Mycobacterium tuberculosis (Mtb) cell division, may involve fuzzy membrane association by proteins via intrinsically disordered regions. The fuzziness is extreme when the conformation and pose of the bound protein and the composition of the proximal lipids are all highly dynamic. Here, we tackled the challenge in characterizing the extreme fuzzy membrane association of the disordered, cytoplasmic N-terminal region (NT) of ChiZ, an Mtb divisome protein, by combining solution and solid-state NMR spectroscopy and molecular dynamics simulations. While membrane-associated NT does not gain any secondary structure, its interactions with lipids are not random, but formed largely by Arg residues predominantly in the second, conserved half of the NT sequence. As NT frolics on the membrane, lipids quickly redistribute, with acidic lipids, relative to zwitterionic lipids, preferentially taking up Arg-proximal positions. The asymmetric engagement of NT arises partly from competition between acidic lipids and acidic residues, all in the first half of NT, for Arg interactions. This asymmetry is accentuated by membrane insertion of the downstream transmembrane helix. This type of semispecific molecular recognition may be a general mechanism by which disordered proteins target membranes.
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Affiliation(s)
- Alan Hicks
- Institute
of Molecular Biophysics, Department of Physics, and Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
- Department
of Chemistry and Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Cristian A. Escobar
- Institute
of Molecular Biophysics, Department of Physics, and Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Timothy A. Cross
- Institute
of Molecular Biophysics, Department of Physics, and Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Huan-Xiang Zhou
- Department
of Chemistry and Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States
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8
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Zhang M, Jang H, Nussinov R. PI3K Driver Mutations: A Biophysical Membrane-Centric Perspective. Cancer Res 2021; 81:237-247. [PMID: 33046444 PMCID: PMC7855922 DOI: 10.1158/0008-5472.can-20-0911] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/24/2020] [Accepted: 10/07/2020] [Indexed: 11/16/2022]
Abstract
Ras activates its effectors at the membrane. Active PI3Kα and its associated kinases/phosphatases assemble at membrane regions enriched in signaling lipids. In contrast, the Raf kinase domain extends into the cytoplasm and its assembly is away from the crowded membrane surface. Our structural membrane-centric outlook underscores the spatiotemporal principles of membrane and signaling lipids, which helps clarify PI3Kα activation. Here we focus on mechanisms of activation driven by PI3Kα driver mutations, spotlighting the PI3Kα double (multiple) activating mutations. Single mutations can be potent, but double mutations are stronger: their combination is specific, a single strong driver cannot fully activate PI3K, and two weak drivers may or may not do so. In contrast, two strong drivers may successfully activate PI3K, where one, for example, H1047R, modulates membrane interactions facilitating substrate binding at the active site (km) and the other, for example, E542K and E545K, reduces the transition state barrier (ka), releasing autoinhibition by nSH2. Although mostly unidentified, weak drivers are expected to be common, so we ask here how common double mutations are likely to be and why PI3Kα with double mutations responds effectively to inhibitors. We provide a structural view of hotspot and weak driver mutations in PI3Kα activation, explain their mechanisms, compare these with mechanisms of Raf activation, and point to targeting cell-specific, chromatin-accessible, and parallel (or redundant) pathways to thwart the expected emergence of drug resistance. Collectively, our biophysical outlook delineates activation and highlights the challenges of drug resistance.
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Affiliation(s)
- Mingzhen Zhang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Laboratory of Cancer Immunometabolism, National Cancer Institute, Frederick, Maryland
| | - Hyunbum Jang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Laboratory of Cancer Immunometabolism, National Cancer Institute, Frederick, Maryland
| | - Ruth Nussinov
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Laboratory of Cancer Immunometabolism, National Cancer Institute, Frederick, Maryland.
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
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9
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Karn R, Emerson IA. Molecular dynamic study on PTEN frameshift mutations in breast cancer provide c2 domain as a potential biomarker. J Biomol Struct Dyn 2020; 40:3132-3143. [PMID: 33183179 DOI: 10.1080/07391102.2020.1845802] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
PTEN is a tumour suppressor gene known for regulating apoptosis, cell growth, and many other pathways. It is one of the most frequently mutated genes comprising the phosphatase domain (PD) and C terminal domain (C2). Direct therapeutic methods are not applicable for targeting PTEN because once gets mutated, it needs restoration. For mutant detection and restoration using PTEN mRNA there is a need to explore various mutations taking place in PTEN, identify their particular domains, and study their interactions within the cellular system. Here, we have tried to highlight a few such regions in the mutated PTEN of breast cancer patients. In this study, we have selected the top-most-occurring PTEN mutation in breast cancer and compared them to determine the specific properties of each mutation and its effect on functionality. Molecular dynamic simulation for 50 ns was performed on five structures to compare the structural behaviour of mutated PTEN in the system. Our finding suggests that frameshift mutations are more damaging and affect the c2 domain. Frameshift mutant fs_ACTT is the highest occurring as well as the most damaging mutation in all the compared structures. Docking study shows that substitution mutations D92H and R130Q causes loss of binding ability towards PIP2 in normal PTEN, interfering the dephosphorylation process. Overall, the C2 domain is more frequently mutated, and the amino acid residues in the C2 domain show more fluctuations compared to the other regions. Our study can provide the basis for selecting frequently mutated C2 domain as a potential therapeutic marker.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Rohit Karn
- Bioinformatics Programming Lab, Department of Biotechnology, School of Bio Sciences and Technology, VIT, Vellore, India
| | - Isaac Arnold Emerson
- Bioinformatics Programming Lab, Department of Biotechnology, School of Bio Sciences and Technology, VIT, Vellore, India
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10
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Cheng Y, Felix B, Othmer HG. The Roles of Signaling in Cytoskeletal Changes, Random Movement, Direction-Sensing and Polarization of Eukaryotic Cells. Cells 2020; 9:E1437. [PMID: 32531876 PMCID: PMC7348768 DOI: 10.3390/cells9061437] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/28/2020] [Accepted: 05/29/2020] [Indexed: 12/21/2022] Open
Abstract
Movement of cells and tissues is essential at various stages during the lifetime of an organism, including morphogenesis in early development, in the immune response to pathogens, and during wound-healing and tissue regeneration. Individual cells are able to move in a variety of microenvironments (MEs) (A glossary of the acronyms used herein is given at the end) by suitably adapting both their shape and how they transmit force to the ME, but how cells translate environmental signals into the forces that shape them and enable them to move is poorly understood. While many of the networks involved in signal detection, transduction and movement have been characterized, how intracellular signals control re-building of the cyctoskeleton to enable movement is not understood. In this review we discuss recent advances in our understanding of signal transduction networks related to direction-sensing and movement, and some of the problems that remain to be solved.
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Affiliation(s)
- Yougan Cheng
- Bristol Myers Squibb, Route 206 & Province Line Road, Princeton, NJ 08543, USA;
| | - Bryan Felix
- School of Mathematics, University of Minnesota, Minneapolis, MN 55445, USA;
| | - Hans G. Othmer
- School of Mathematics, University of Minnesota, Minneapolis, MN 55445, USA;
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11
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Yoshioka D, Fukushima S, Koteishi H, Okuno D, Ide T, Matsuoka S, Ueda M. Single-molecule imaging of PI(4,5)P 2 and PTEN in vitro reveals a positive feedback mechanism for PTEN membrane binding. Commun Biol 2020; 3:92. [PMID: 32111929 PMCID: PMC7048775 DOI: 10.1038/s42003-020-0818-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 02/10/2020] [Indexed: 01/21/2023] Open
Abstract
PTEN, a 3-phosphatase of phosphoinositide, regulates asymmetric PI(3,4,5)P3 signaling for the anterior-posterior polarization and migration of motile cells. PTEN acts through posterior localization on the plasma membrane, but the mechanism for this accumulation is poorly understood. Here we developed an in vitro single-molecule imaging assay with various lipid compositions and use it to demonstrate that the enzymatic product, PI(4,5)P2, stabilizes PTEN's membrane-binding. The dissociation kinetics and lateral mobility of PTEN depended on the PI(4,5)P2 density on artificial lipid bilayers. The basic residues of PTEN were responsible for electrostatic interactions with anionic PI(4,5)P2 and thus the PI(4,5)P2-dependent stabilization. Single-molecule imaging in living Dictyostelium cells revealed that these interactions were indispensable for the stabilization in vivo, which enabled efficient cell migration by accumulating PTEN posteriorly to restrict PI(3,4,5)P3 distribution to the anterior. These results suggest that PI(4,5)P2-mediated positive feedback and PTEN-induced PI(4,5)P2 clustering may be important for anterior-posterior polarization.
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Affiliation(s)
- Daisuke Yoshioka
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 565-0043, Japan
- Center for Biosystems Dynamics Research (BDR), RIKEN, Suita, Osaka, 565-0874, Japan
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Seiya Fukushima
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 565-0043, Japan
- Center for Biosystems Dynamics Research (BDR), RIKEN, Suita, Osaka, 565-0874, Japan
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Hiroyasu Koteishi
- Center for Biosystems Dynamics Research (BDR), RIKEN, Suita, Osaka, 565-0874, Japan
| | - Daichi Okuno
- Center for Biosystems Dynamics Research (BDR), RIKEN, Suita, Osaka, 565-0874, Japan
| | - Toru Ide
- Graduate School of Natural Science and Technology, Okayama University, Okayama-shi, Okayama, 700-8530, Japan
| | - Satomi Matsuoka
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 565-0043, Japan.
- Center for Biosystems Dynamics Research (BDR), RIKEN, Suita, Osaka, 565-0874, Japan.
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan.
| | - Masahiro Ueda
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 565-0043, Japan.
- Center for Biosystems Dynamics Research (BDR), RIKEN, Suita, Osaka, 565-0874, Japan.
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan.
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12
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Muller MP, Jiang T, Sun C, Lihan M, Pant S, Mahinthichaichan P, Trifan A, Tajkhorshid E. Characterization of Lipid-Protein Interactions and Lipid-Mediated Modulation of Membrane Protein Function through Molecular Simulation. Chem Rev 2019; 119:6086-6161. [PMID: 30978005 PMCID: PMC6506392 DOI: 10.1021/acs.chemrev.8b00608] [Citation(s) in RCA: 133] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The cellular membrane constitutes one of the most fundamental compartments of a living cell, where key processes such as selective transport of material and exchange of information between the cell and its environment are mediated by proteins that are closely associated with the membrane. The heterogeneity of lipid composition of biological membranes and the effect of lipid molecules on the structure, dynamics, and function of membrane proteins are now widely recognized. Characterization of these functionally important lipid-protein interactions with experimental techniques is however still prohibitively challenging. Molecular dynamics (MD) simulations offer a powerful complementary approach with sufficient temporal and spatial resolutions to gain atomic-level structural information and energetics on lipid-protein interactions. In this review, we aim to provide a broad survey of MD simulations focusing on exploring lipid-protein interactions and characterizing lipid-modulated protein structure and dynamics that have been successful in providing novel insight into the mechanism of membrane protein function.
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Affiliation(s)
- Melanie P. Muller
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- College of Medicine
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Tao Jiang
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Chang Sun
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Muyun Lihan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Shashank Pant
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Paween Mahinthichaichan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Anda Trifan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Emad Tajkhorshid
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- College of Medicine
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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13
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Irvine WA, Flanagan JU, Allison JR. Computational Prediction of Amino Acids Governing Protein-Membrane Interaction for the PIP3 Cell Signaling System. Structure 2019; 27:371-380.e3. [DOI: 10.1016/j.str.2018.10.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 08/13/2018] [Accepted: 10/18/2018] [Indexed: 10/27/2022]
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14
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Kawanabe A, Hashimoto M, Nishizawa M, Nishizawa K, Narita H, Yonezawa T, Jinno Y, Sakata S, Nakagawa A, Okamura Y. The hydrophobic nature of a novel membrane interface regulates the enzyme activity of a voltage-sensing phosphatase. eLife 2018; 7:41653. [PMID: 30484774 PMCID: PMC6298786 DOI: 10.7554/elife.41653] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Accepted: 11/28/2018] [Indexed: 01/24/2023] Open
Abstract
Voltage-sensing phosphatases (VSP) contain a voltage sensor domain (VSD) similar to that of voltage-gated ion channels but lack a pore-gate domain. A VSD in a VSP regulates the cytoplasmic catalytic region (CCR). However, the mechanisms by which the VSD couples to the CCR remain elusive. Here we report a membrane interface (named ‘the hydrophobic spine’), which is essential for the coupling of the VSD and CCR. Our molecular dynamics simulations suggest that the hydrophobic spine of Ciona intestinalis VSP (Ci-VSP) provides a hinge-like motion for the CCR through the loose membrane association of the phosphatase domain. Electrophysiological experiments indicate that the voltage-dependent phosphatase activity of Ci-VSP depends on the hydrophobicity and presence of an aromatic ring in the hydrophobic spine. Analysis of conformational changes in the VSD and CCR suggests that the VSP has two states with distinct enzyme activities and that the second transition depends on the hydrophobic spine.
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Affiliation(s)
- Akira Kawanabe
- Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Masaki Hashimoto
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | | | | | - Hirotaka Narita
- Institute for Protein Research, Osaka University, Osaka, Japan
| | - Tomoko Yonezawa
- Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Yuka Jinno
- Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Souhei Sakata
- Department of Physiology, Division of Life Sciences, Faculty of Medicine, Osaka Medical College, Osaka, Japan
| | | | - Yasushi Okamura
- Integrative Physiology, Department of Physiology, Graduate School of Medicine, Osaka University, Osaka, Japan.,Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
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15
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A pathogenic role for germline PTEN variants which accumulate into the nucleus. Eur J Hum Genet 2018; 26:1180-1187. [PMID: 29706633 DOI: 10.1038/s41431-018-0155-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 03/27/2018] [Accepted: 03/30/2018] [Indexed: 11/08/2022] Open
Abstract
The PTEN gene encodes a master regulator protein that exerts essential functions both in the cytoplasm and in the nucleus. PTEN is mutated in the germline of both patients with heterogeneous tumor syndromic diseases, categorized as PTEN hamartoma tumor syndrome (PHTS), and a group affected with autism spectrum disorders (ASD). Previous studies have unveiled the functional heterogeneity of PTEN variants found in both patient cohorts, making functional studies necessary to provide mechanistic insights related to their pathogenicity. Here, we have functionally characterized a PTEN missense variant [c.49C>G; p.(Gln17Glu); Q17E] associated to both PHTS and ASD patients. The PTEN Q17E variant displayed partially reduced PIP3-catalytic activity and normal stability in cells, as shown using S. cerevisiae and mammalian cell experimental models. Remarkably, PTEN Q17E accumulated in the nucleus, in a process involving the PTEN N-terminal nuclear localization sequence. The analysis of additional germline-associated PTEN N-terminal variants illustrated the existence of a PTEN N-terminal region whose targeting in disease causes PTEN nuclear accumulation, in parallel with defects in PIP3-catalytic activity in cells. Our findings highlight the frequent occurrence of PTEN gene mutations targeting PTEN N-terminus whose pathogenicity may be related, at least in part, with the retention of PTEN in the nucleus. This could be important for the implementation of precision therapies for patients with alterations in the PTEN pathway.
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16
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Liu C, Deb S, Ferreira VS, Xu E, Baumgart T. Kinetics of PTEN-mediated PI(3,4,5)P3 hydrolysis on solid supported membranes. PLoS One 2018; 13:e0192667. [PMID: 29447222 PMCID: PMC5813967 DOI: 10.1371/journal.pone.0192667] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 01/26/2018] [Indexed: 11/18/2022] Open
Abstract
Phosphatidylinositides play important roles in cellular signaling and migration. Phosphatidylinositol-3,4,5-trisphosphate (PI(3,4,5)P3) is an important phosphatidylinositide because it acts as a secondary messenger to trigger cell movement and proliferation. A high level of PI(3,4,5)P3 at the plasma membrane is known to contribute to tumorigenesis. One key enzyme that regulates PI(3,4,5)P3 levels at the plasma membrane is phosphatase and tensin homologue deleted on chromosome 10 (PTEN), which dephosphorylates PI(3,4,5)P3 through hydrolysis to form phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2). It has been reported that PI(4,5)P2 is involved in positive feedback in the PI(3,4,5)P3 hydrolysis by PTEN. However, how PI(3,4,5)P3 dephosphorylation by PTEN is regulated, is still under debate. How other PI(3,4,5)P3-binding proteins affect the dephosphorylation kinetics catalyzed by PTEN also remains unclear. Here, we develop a fluorescent-protein biosensor approach to study how PI(3,4,5)P3 dephosphorylation is regulated by PTEN as well as its membrane-mediated feedback mechanisms. Our observation of sigmoidal kinetics of the PI(3,4,5)P3 hydrolysis reaction supports the notion of autocatalysis in PTEN function. We developed a kinetic model to describe the observed reaction kinetics, which allowed us to i) distinguish between membrane-recruitment and allosteric activation of PTEN by PI(4,5)P2, ii) account for the influence of the biosensor on the observed reaction kinetics, and iii) demonstrate that all of these mechanisms contribute to the kinetics of PTEN-mediated catalysis.
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Affiliation(s)
- Chun Liu
- Department of Chemistry, School of Arts & Sciences, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Sanghamitra Deb
- Department of Chemistry, School of Arts & Sciences, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Vinicius S Ferreira
- Department of Chemistry, School of Arts & Sciences, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Eric Xu
- Department of Chemistry, School of Arts & Sciences, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Tobias Baumgart
- Department of Chemistry, School of Arts & Sciences, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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17
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Hung HM, Hang TD, Nguyen MT. Molecular details of spontaneous insertion and interaction of HCV non-structure 3 protease protein domain with PIP2-containing membrane. Proteins 2018; 86:423-433. [PMID: 29341226 DOI: 10.1002/prot.25458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 01/02/2018] [Accepted: 01/11/2018] [Indexed: 12/16/2022]
Abstract
Hepatitis C virus (HCV), known as the leading cause of liver cirrhosis, viral hepatitis, and hepatocellular carcinoma, has been affecting more than 150 million people globally. The HCV non-structure 3 (NS3) protease protein domain plays a key role in HCV replication and pathogenesis; and is currently a primary target for HCV antiviral therapy. Through unbiased molecular dynamics simulations which take advantage of the novel highly mobile membrane mimetic model, we constructed the membrane-bound state of the protein domain at the atomic level. Our results indicated that protease domain of HCV NS3 protein can spontaneously bind and penetrate to an endoplasmic reticulum complex membrane containing phosphatidylinositol 4,5-bisphosphate (PIP2). An amphipathic helix α0 and loop S1 show their anchoring role to keep the protein on the membrane surface. Proper orientation of the protein domain at membrane surface was identified through measuring tilt angles of two specific vectors, wherein residue R161 plays a crucial role in its final orientation. Remarkably, PIP2 molecules were observed to bind to three main sites of the protease domain via specific electrostatic contacts and hydrogen bonds. PIP2-interaction determines the protein orientation at the membrane while both hydrophobic interplay and PIP2-interaction can stabilize the NS3 - membrane complex. Simulated results provide us with a detailed characterization of insertion, orientation and PIP2-interaction of NS3 protease domain at membrane environment, thus enhancing our understanding of structural functions and mechanism for the association of HCV non-structure 3 protein with respect to ER membranes.
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Affiliation(s)
- Huynh Minh Hung
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, Leuven, B-3001, Belgium.,Department of Chemistry, Quy Nhon University, Quy Nhon, Vietnam
| | - Tran Dieu Hang
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, Leuven, B-3001, Belgium.,Department of Chemistry, Quy Nhon University, Quy Nhon, Vietnam
| | - Minh Tho Nguyen
- Computational Chemistry Research Group, Ton Duc Thang University, Ho Chi Minh City, Vietnam.,Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam.,Department of Chemistry, KU Leuven, Celestijnenlaan 200F, Leuven, B-3001, Belgium
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18
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Willems N, Lelimousin M, Koldsø H, Sansom MSP. Interfacial activation of M37 lipase: A multi-scale simulation study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:340-349. [PMID: 27993564 PMCID: PMC5287222 DOI: 10.1016/j.bbamem.2016.12.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 10/31/2016] [Accepted: 12/15/2016] [Indexed: 11/25/2022]
Abstract
Lipases are enzymes of biotechnological importance that function at the interface formed between hydrophobic and aqueous environments. Hydrophobic interfaces can induce structural transitions in lipases that result in an increase in enzyme activity, although the detailed mechanism of this process is currently not well understood for many lipases. Here, we present a multi-scale molecular dynamics simulation study of how different interfaces affect the conformational dynamics of the psychrophilic lipase M37. Our simulations show that M37 lipase is able to interact both with anionic lipid bilayers and with triglyceride surfaces. Interfacial interactions with triglyceride surfaces promote large-scale motions of the lid region of M37, spanning residues 235-283, revealing an entry pathway to the catalytic site for substrates. Importantly, these results suggest a potential activation mechanism for M37 that deviates from other related enzymes, such as Thermomyces lanuginosus lipase. We also investigated substrate binding in M37 by using steered MD simulations, confirming the open state of this lipase. The exposure of hydrophobic residues within lid and active site flap regions (residues 94-110) during the activation process provides insights into the functional effect of hydrophobic surfaces on lipase activation.
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Affiliation(s)
- Nathalie Willems
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Mickaël Lelimousin
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Heidi Koldsø
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom.
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19
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Hung HM, Hang TD, Nguyen MT. Multiscale simulations on conformational dynamics and membrane interactions of the non-structural 2 (NS2) transmembrane domain. Biochem Biophys Res Commun 2016; 478:193-198. [DOI: 10.1016/j.bbrc.2016.07.069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Accepted: 07/16/2016] [Indexed: 01/08/2023]
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20
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Jiang L, Wang C, Lei F, Zhang L, Zhang X, Liu A, Wu G, Zhu J, Song L. miR-93 promotes cell proliferation in gliomas through activation of PI3K/Akt signaling pathway. Oncotarget 2016; 6:8286-99. [PMID: 25823655 PMCID: PMC4480752 DOI: 10.18632/oncotarget.3221] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 01/26/2015] [Indexed: 12/17/2022] Open
Abstract
The PI3K/Akt signaling pathway is frequently activated in various human cancer types and plays essential roles in development and progression of cancers. Multiple regulators, such as phosphatase and tensin homolog (PTEN) and PH domain leucine rich repeat protein phosphatases (PHLPP), have also found to be involved in suppression of the PI3K/Akt signaling pathway. However, how suppressive effects mediated by these regulators are concomitantly disrupted in cancers, which display constitutively activated PI3K/Akt signaling, remains puzzling. In the present study, we reported that the expression of miR-93 was markedly upregulated in glioma cell lines and clinical glioma tissues. Statistical analysis revealed that miR-93 levels significantly correlated with clinicopathologic grade and overall survival in gliomas. Furthermore, we found that overexpressing miR-93 promoted, but inhibition of miR-93 reduced, glioma cell proliferation and cell-cycle progression. We demonstrated that miR-93 activated PI3K/Akt signaling through directly suppressing PTEN, PHLPP2 and FOXO3 expression via targeting their 3'UTRs. Therefore, our results suggest that miR-93 might play an important role in glioma progression and uncover a novel mechanism for constitutive PI3K/Akt activation in gliomas.
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Affiliation(s)
- Lili Jiang
- Department of Pathophysiology, Guangzhou Medical University, Guangzhou 510182, China.,State Key Laboratory of Oncology in Southern China, Department of Experimental Research, Cancer Centre, Sun Yat-sen University, Guangzhou 510060, China
| | - Chanjuan Wang
- Department of the Central Laboratory, The First Affiliated Hospital/School of Clinical Medicine of Guangdong Pharmaceutical University, Guangzhou 510080, China
| | - Fangyong Lei
- State Key Laboratory of Oncology in Southern China, Department of Experimental Research, Cancer Centre, Sun Yat-sen University, Guangzhou 510060, China
| | - Longjuan Zhang
- Laboratory of Surgery, First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China
| | - Xin Zhang
- State Key Laboratory of Oncology in Southern China, Department of Experimental Research, Cancer Centre, Sun Yat-sen University, Guangzhou 510060, China
| | - Aibin Liu
- Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Geyan Wu
- Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Jinrong Zhu
- Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong 510080, China
| | - Libing Song
- State Key Laboratory of Oncology in Southern China, Department of Experimental Research, Cancer Centre, Sun Yat-sen University, Guangzhou 510060, China
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21
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Herzog FA, Braun L, Schoen I, Vogel V. Improved Side Chain Dynamics in MARTINI Simulations of Protein–Lipid Interfaces. J Chem Theory Comput 2016; 12:2446-58. [DOI: 10.1021/acs.jctc.6b00122] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Florian A. Herzog
- Laboratory of Applied Mechanobiology,
Department of Health Sciences and Technology, ETH Zurich, Vladimir-Prelog-Weg
4, 8093 Zurich, Switzerland
| | - Lukas Braun
- Laboratory of Applied Mechanobiology,
Department of Health Sciences and Technology, ETH Zurich, Vladimir-Prelog-Weg
4, 8093 Zurich, Switzerland
| | - Ingmar Schoen
- Laboratory of Applied Mechanobiology,
Department of Health Sciences and Technology, ETH Zurich, Vladimir-Prelog-Weg
4, 8093 Zurich, Switzerland
| | - Viola Vogel
- Laboratory of Applied Mechanobiology,
Department of Health Sciences and Technology, ETH Zurich, Vladimir-Prelog-Weg
4, 8093 Zurich, Switzerland
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22
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Masson GR, Burke JE, Williams RL. Methods in the Study of PTEN Structure: X-Ray Crystallography and Hydrogen Deuterium Exchange Mass Spectrometry. Methods Mol Biol 2016; 1388:215-30. [PMID: 27033079 DOI: 10.1007/978-1-4939-3299-3_14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Despite its small size and deceptively simple domain organization, PTEN remains a challenging structural target due to its N- and C-terminal intrinsically disordered segments, and the conformational heterogeneity caused by phosphorylation of its C terminus. Using hydrogen/deuterium exchange mass spectrometry (HDX-MS), it is possible to probe the conformational dynamics of the disordered termini, and also to determine how PTEN binds to lipid membranes. Here, we describe how to purify recombinant, homogenously dephosphorylated PTEN from a eukaryotic system for subsequent investigation with HDX-MS or crystallography.
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Affiliation(s)
- Glenn R Masson
- Laboratory of Molecular Biology, Medical Research Council (MRC), Francis Crick Avenue, Cambridge Biomedical campus, Cambridge, CB2 0QH, UK
| | - John E Burke
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Drive, Victoria, BC, Canada, V8P 5C2
| | - Roger L Williams
- Laboratory of Molecular Biology, Medical Research Council (MRC), Francis Crick Avenue, Cambridge Biomedical campus, Cambridge, CB2 0QH, UK.
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23
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Abstract
PTEN subcellular localization is fundamental in the execution of the distinct PTEN biological activities, including not only its PI(3,4,5)P3 phosphatase activity when associated to membranes but also its subcellular compartment-specific interactions with regulatory and effector proteins, including those exerted in the nucleus. As a consequence, PTEN subcellular localization is tightly regulated in vivo by both intrinsic and extrinsic mechanisms. The plasma membrane/nucleus/cytoplasm partitioning of PTEN has been the focus of several studies, both from a mechanistic and from a disease-association point of view. Here, we summarize the current knowledge on PTEN plasma membrane/nucleus/cytoplasm distribution, and present subcellular fractionation, immunofluorescence, and immunohistochemical methods to study the distribution and shuttling of PTEN between these subcellular compartments.
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Affiliation(s)
- Anabel Gil
- Centro de Investigación Príncipe Felipe, Valencia, 46013, Spain
- Department of Hematology and Medical Oncology, Biomedical Research Institute INCLIVA, Valencia, 46010, Spain
| | - José I López
- Department of Pathology, Cruces University Hospital, University of the Basque Country (UPV/EHU), Barakaldo, 48903, Spain
- Biocruces Health Research Institute, Plaza de Cruces s/n, Barakaldo, Bizkaia, 48903, Spain
| | - Rafael Pulido
- Centro de Investigación Príncipe Felipe, Valencia, 46013, Spain.
- Biocruces Health Research Institute, Plaza de Cruces s/n, Barakaldo, Bizkaia, 48903, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, 48013, Spain.
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24
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The intrinsically disordered tails of PTEN and PTEN-L have distinct roles in regulating substrate specificity and membrane activity. Biochem J 2015; 473:135-44. [PMID: 26527737 PMCID: PMC4700475 DOI: 10.1042/bj20150931] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 11/02/2015] [Indexed: 11/17/2022]
Abstract
Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a lipid and protein phosphatase, and both activities are necessary for its role as a tumour suppressor. PTEN activity is controlled by phosphorylation of its intrinsically disordered C-terminal tail. A recently discovered variant of PTEN, PTEN-long (PTEN-L), has a 173-residue N-terminal extension that causes PTEN-L to exhibit unique behaviour, such as movement from one cell to another. Using hydrogen/deuterium exchange mass spectrometry (HDX-MS) and biophysical assays, we show that both the N-terminal extension of PTEN-L and C-terminal tail of PTEN affect the phosphatase activity using unique mechanisms. Phosphorylation of six residues in the C-terminal tail of PTEN results in auto-inhibitory interactions with the phosphatase and C2 domains, effectively blocking both the active site and the membrane-binding interface of PTEN. Partially dephosphorylating PTEN on pThr(366)/pSer(370) results in sufficient exposure of the active site to allow a selective activation for soluble substrates. Using HDX-MS, we identified a membrane-binding element in the N-terminal extension of PTEN-L, termed the membrane-binding helix (MBH). The MBH radically alters the membrane binding mechanism of PTEN-L compared with PTEN, switching PTEN-L to a 'scooting' mode of catalysis from the 'hopping' mode that is characteristic of PTEN.
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25
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Chia YCJ, Catimel B, Lio DSS, Ang CS, Peng B, Wu H, Zhu HJ, Cheng HC. The C-terminal tail inhibitory phosphorylation sites of PTEN regulate its intrinsic catalytic activity and the kinetics of its binding to phosphatidylinositol-4,5-bisphosphate. Arch Biochem Biophys 2015; 587:48-60. [PMID: 26471078 DOI: 10.1016/j.abb.2015.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 10/04/2015] [Accepted: 10/08/2015] [Indexed: 10/22/2022]
Abstract
Dephosphorylation of four major C-terminal tail sites and occupancy of the phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2]-binding site of PTEN cooperate to activate its phospholipid phosphatase activity and facilitate its recruitment to plasma membrane. Our investigation of the mechanism by which phosphorylation of these C-terminal sites controls the PI(4,5)P2-binding affinity and catalytic activity of PTEN resulted in the following findings. First, dephosphorylation of all four sites leads to full activation; and phosphorylation of any one site significantly reduces the intrinsic catalytic activity of PTEN. These findings suggest that coordinated inhibition of the upstream protein kinases and activation of the protein phosphatases targeting the four sites are needed to fully activate PTEN phosphatase activity. Second, PI(4,5)P2 cannot activate the phosphopeptide phosphatase activity of PTEN, suggesting that PI(4,5)P2 can only activate the phospholipid phosphatase activity but not the phosphoprotein phosphatase activity of PTEN. Third, dephosphorylation of all four sites significantly decreases the affinity of PTEN for PI(4,5)P2. Since PI(4,5)P2 is a major phospholipid co-localizing with the phospholipid- and phosphoprotein-substrates in plasma membrane, we hypothesise that the reduced affinity facilitates PTEN to "hop" on the plasma membrane to dephosphorylate these substrates.
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Affiliation(s)
- Yeong-Chit Joel Chia
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia; Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Bruno Catimel
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Daisy Sio Seng Lio
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia; Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Ching-Seng Ang
- Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Benjamin Peng
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Hong Wu
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia; Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Hong-Jian Zhu
- Department of Surgery, University of Melbourne, Royal Melbourne Hospital, Parkville, Victoria 3052, Australia
| | - Heung-Chin Cheng
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia; Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria 3010, Australia.
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26
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Meng Z, Jia LF, Gan YH. PTEN activation through K163 acetylation by inhibiting HDAC6 contributes to tumour inhibition. Oncogene 2015; 35:2333-44. [PMID: 26279303 DOI: 10.1038/onc.2015.293] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Revised: 06/09/2015] [Accepted: 07/06/2015] [Indexed: 01/25/2023]
Abstract
Phosphatase and tensin homologue deleted on chromosome 10 (PTEN), an important tumour-suppressor gene, is mutated, downregulated or dysfunctional in many tumours. The phosphatase activity of PTEN depends on membrane translocation (activation). As promising anti-cancer agents, histone deacetylase (HDAC) inhibitors, particularly trichostatin A (TSA), can promote PTEN membrane translocation, but the underlying mechanism remains unknown. In this study, we revealed that non-selective HDAC inhibitors, namely, TSA or suberoylanilide hydroxamic acid (SAHA), induced PTEN membrane translocation through PTEN acetylation at K163 by inhibiting HDAC6. K163 acetylation inhibited the interaction of the PTEN C-tail with the remaining part of PTEN, resulting in PTEN membrane translocation. Overexpression of wild-type PTEN, but not K163-mutated PTEN, facilitated the inhibition of cell proliferation, migration and invasion, as well as xenograft tumour growth, induced by SAHA or tubastatin A, an HDAC6-specific inhibitor. These results indicated that PTEN activation by inhibiting HDAC6 significantly contributed to tumour inhibition. Therefore, non-selective HDAC or HDAC6-specific inhibitors may be more clinically suitable to treat tumours without PTEN mutations or deletions.
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Affiliation(s)
- Z Meng
- Central Laboratory, Peking University School and Hospital of Stomatology, Beijing, China.,Department of Oral & Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China
| | - L-F Jia
- Central Laboratory, Peking University School and Hospital of Stomatology, Beijing, China
| | - Y-H Gan
- Central Laboratory, Peking University School and Hospital of Stomatology, Beijing, China.,Department of Oral & Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China
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27
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Nguyen HN, Yang JM, Miyamoto T, Itoh K, Rho E, Zhang Q, Inoue T, Devreotes PN, Sesaki H, Iijima M. Opening the conformation is a master switch for the dual localization and phosphatase activity of PTEN. Sci Rep 2015. [PMID: 26216063 PMCID: PMC4517176 DOI: 10.1038/srep12600] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Tumor suppressor PTEN mainly functions at two subcellular locations, the plasma membrane and the nucleus. At the plasma membrane, PTEN dephosphorylates the tumorigenic second messenger PIP3, which drives cell proliferation and migration. In the nucleus, PTEN controls DNA repair and genome stability independently of PIP3. Whereas the concept that a conformational change regulates protein function through post-translational modifications has been well established in biology, it is unknown whether a conformational change simultaneously controls dual subcellular localizations of proteins. Here, we discovered that opening the conformation of PTEN is the crucial upstream event that determines its key dual localizations of this crucial tumor suppressor. We identify a critical conformational switch that regulates PTEN's localization. Most PTEN molecules are held in the cytosol in a closed conformation by intramolecular interactions between the C-terminal tail and core region. Dephosphorylation of the tail opens the conformation and exposes the membrane-binding regulatory interface in the core region, recruiting PTEN to the membrane. Moreover, a lysine at residue 13 is also exposed and when ubiquitinated, transports PTEN to the nucleus. Thus, opening the conformation of PTEN is a key mechanism that enhances its dual localization and enzymatic activity, providing a potential therapeutic strategy in cancer treatments.
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Affiliation(s)
- Hoai-Nghia Nguyen
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Jr-Ming Yang
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Takafumi Miyamoto
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Kie Itoh
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Elmer Rho
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Qiang Zhang
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Takanari Inoue
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Peter N Devreotes
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Hiromi Sesaki
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Miho Iijima
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD
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Lamprakis C, Stocker A, Cascella M. Mechanisms of recognition and binding of α-TTP to the plasma membrane by multi-scale molecular dynamics simulations. Front Mol Biosci 2015; 2:36. [PMID: 26191529 PMCID: PMC4487086 DOI: 10.3389/fmolb.2015.00036] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 06/15/2015] [Indexed: 12/12/2022] Open
Abstract
We used multiple sets of simulations both at the atomistic and coarse-grained level of resolution to investigate interaction and binding of α-tochoperol transfer protein (α-TTP) to phosphatidylinositol phosphate lipids (PIPs). Our calculations indicate that enrichment of membranes with such lipids facilitate membrane anchoring. Atomistic models suggest that PIP can be incorporated into the binding cavity of α-TTP and therefore confirm that such protein can work as lipid exchanger between the endosome and the plasma membrane. Comparison of the atomistic models of the α-TTP-PIPs complex with membrane-bound α-TTP revealed different roles for the various basic residues composing the basic patch that is key for the protein/ligand interaction. Such residues are of critical importance as several point mutations at their position lead to severe forms of ataxia with vitamin E deficiency (AVED) phenotypes. Specifically, R221 is main residue responsible for the stabilization of the complex. R68 and R192 exchange strong interactions in the protein or in the membrane complex only, suggesting that the two residues alternate contact formation, thus facilitating lipid flipping from the membrane into the protein cavity during the lipid exchange process. Finally, R59 shows weaker interactions with PIPs anyway with a clear preference for specific phosphorylation positions, hinting a role in early membrane selectivity for the protein. Altogether, our simulations reveal significant aspects at the atomistic scale of interactions of α-TTP with the plasma membrane and with PIP, providing clarifications on the mechanism of intracellular vitamin E trafficking and helping establishing the role of key residue for the functionality of α-TTP.
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Affiliation(s)
- Christos Lamprakis
- Department of Chemistry and Biochemistry, University of Bern Bern, Switzerland
| | - Achim Stocker
- Department of Chemistry and Biochemistry, University of Bern Bern, Switzerland
| | - Michele Cascella
- Department of Chemistry, Centre for Theoretical and Computational Chemistry, University of Oslo Oslo, Norway
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29
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Interactions of peripheral proteins with model membranes as viewed by molecular dynamics simulations. Biochem Soc Trans 2014; 42:1418-24. [DOI: 10.1042/bst20140144] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Many cellular signalling and related events are triggered by the association of peripheral proteins with anionic lipids in the cell membrane (e.g. phosphatidylinositol phosphates or PIPs). This association frequently occurs via lipid-binding modules, e.g. pleckstrin homology (PH), C2 and four-point-one, ezrin, radixin, moesin (FERM) domains, present in peripheral and cytosolic proteins. Multiscale simulation approaches that combine coarse-grained and atomistic MD simulations may now be applied with confidence to investigate the molecular mechanisms of the association of peripheral proteins with model bilayers. Comparisons with experimental data indicate that such simulations can predict specific peripheral protein–lipid interactions. We discuss the application of multiscale MD simulation and related approaches to investigate the association of peripheral proteins which contain PH, C2 or FERM-binding modules with lipid bilayers of differing phospholipid composition, including bilayers containing multiple PIP molecules.
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30
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Kreis P, Leondaritis G, Lieberam I, Eickholt BJ. Subcellular targeting and dynamic regulation of PTEN: implications for neuronal cells and neurological disorders. Front Mol Neurosci 2014; 7:23. [PMID: 24744697 PMCID: PMC3978343 DOI: 10.3389/fnmol.2014.00023] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 03/12/2014] [Indexed: 01/13/2023] Open
Abstract
PTEN is a lipid and protein phosphatase that regulates a diverse range of cellular mechanisms. PTEN is mainly present in the cytosol and transiently associates with the plasma membrane to dephosphorylate PI(3,4,5)P3, thereby antagonizing the PI3-Kinase signaling pathway. Recently, PTEN has been shown to associate also with organelles such as the endoplasmic reticulum (ER), the mitochondria, or the nucleus, and to be secreted outside of the cell. In addition, PTEN dynamically localizes to specialized sub-cellular compartments such as the neuronal growth cone or dendritic spines. The diverse localizations of PTEN imply a tight temporal and spatial regulation, orchestrated by mechanisms such as posttranslational modifications, formation of distinct protein–protein interactions, or the activation/recruitment of PTEN downstream of external cues. The regulation of PTEN function is thus not only important at the enzymatic activity level, but is also associated to its spatial distribution. In this review we will summarize (i) recent findings that highlight mechanisms controlling PTEN movement and sub-cellular localization, and (ii) current understanding of how PTEN localization is achieved by mechanisms controlling posttranslational modification, by association with binding partners and by PTEN structural or activity requirements. Finally, we will discuss the possible roles of compartmentalized PTEN in developing and mature neurons in health and disease.
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Affiliation(s)
- Patricia Kreis
- MRC Centre for Developmental Neurobiology, King's College London London, UK
| | - George Leondaritis
- MRC Centre for Developmental Neurobiology, King's College London London, UK ; Institute of Biochemistry, Charité - Universitätsmedizin Berlin Berlin, Germany
| | - Ivo Lieberam
- MRC Centre for Developmental Neurobiology, King's College London London, UK
| | - Britta J Eickholt
- MRC Centre for Developmental Neurobiology, King's College London London, UK ; Institute of Biochemistry, Charité - Universitätsmedizin Berlin Berlin, Germany
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31
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Kalli AC, Devaney I, Sansom MSP. Interactions of phosphatase and tensin homologue (PTEN) proteins with phosphatidylinositol phosphates: insights from molecular dynamics simulations of PTEN and voltage sensitive phosphatase. Biochemistry 2014; 53:1724-32. [PMID: 24588644 PMCID: PMC4167384 DOI: 10.1021/bi5000299] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
![]()
The
phosphatase and tensin homologue (PTEN) and the Ciona
intestinalis voltage sensitive phosphatase (Ci-VSP) are both
phosphatidylinositol phosphate (PIP) phosphatases that contain a C2
domain. PTEN is a tumor suppressor protein that acts as a phosphatase
on PIP3 in mammalian cell membranes. It contains two principal
domains:
a phosphatase domain (PD) and a C2 domain. Despite detailed structural
and functional characterization, less is known about its mechanism
of interaction with PIP-containing lipid bilayers. Ci-VSP consists
of an N-terminal transmembrane voltage sensor domain and a C-terminal
PTEN domain, which in turn contains a PD and a C2 domain. The nature
of the interaction of the PTEN domain of Ci-VSP with membranes has
not been well established. We have used multiscale molecular dynamics
simulations to define the interaction mechanisms
of PTEN and of the Ci-VSP PTEN domains with PIP-containing lipid bilayers.
Our results suggest a novel mechanism of association of the PTEN with
such bilayers, in which an initial electrostatics-driven encounter
of the protein and bilayer is followed by reorientation of the protein
to optimize its interactions with PIP molecules in the membrane. Although
a PIP3 molecule binds close to the active site of PTEN,
our simulations suggest a further conformational change of the protein
may be required for catalytically productive binding to occur. Ci-VSP
interacted with membranes in an orientation comparable to that of
PTEN but bound directly to PIP-containing membranes without a subsequent
reorientation step. Again, PIP3 bound close to the active
site of the Ci-VSP PD, but not in a catalytically productive manner.
Interactions of Ci-VSP with the bilayer induced clustering of PIP
molecules around the protein.
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Affiliation(s)
- Antreas C Kalli
- Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, U.K
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Kalli AC, Morgan G, Sansom MSP. Interactions of the auxilin-1 PTEN-like domain with model membranes result in nanoclustering of phosphatidyl inositol phosphates. Biophys J 2014; 105:137-45. [PMID: 23823232 DOI: 10.1016/j.bpj.2013.05.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 05/06/2013] [Accepted: 05/07/2013] [Indexed: 11/18/2022] Open
Abstract
Auxilin-1 is a neuron-specific membrane-binding protein involved in a late stage of clathrin-mediated endocytosis. It recruits Hsc70, thus initiating uncoating of the clathrin-coated vesicles. Interactions of auxilin-1 with the vesicle membrane are crucial for this function and are mediated via an N-terminal PTEN-like domain. We have used multiscale molecular dynamics simulations to probe the interactions of the auxilin-1 PTEN-like domain with lipid bilayers containing differing phospholipid composition, including bilayers containing phosphatidyl inositol phosphates. Our results suggest a novel, to our knowledge, model for the auxilin/membrane encounter and subsequent interactions. Negatively charged lipids (especially PIP2) enhance binding of auxilin to lipid bilayers and facilitate its correct orientation relative to the membrane. Mutations in three basic residues (R301E/R307E/K311E) of the C2 subdomain of the PTEN-like domain perturbed its interaction with the bilayer, changing its orientation. The interaction of membrane-bound auxilin-1 PTEN-like domain with negatively charged lipid headgroups results in nanoclustering of PIP2 molecules in the adjacent bilayer leaflet.
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Affiliation(s)
- Antreas C Kalli
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
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33
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Mechanism of human PTEN localization revealed by heterologous expression in Dictyostelium. Oncogene 2013; 33:5688-96. [PMID: 24292679 PMCID: PMC4041858 DOI: 10.1038/onc.2013.507] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 09/26/2013] [Accepted: 10/21/2013] [Indexed: 12/16/2022]
Abstract
Phosphatase and tensin homolog (PTEN) is one of the most frequently mutated tumor suppressor genes in cancers. PTEN plays a central role in phosphatidylinositol (3,4,5)-trisphosphate (PIP3) signaling and converts PIP3 to phosphatidylinositol (4,5)-bisphosphate (PIP2) at the plasma membrane. Despite its importance, the mechanism that mediates membrane localization of PTEN is poorly understood. Here, we generated a library that contains GFP fused to randomly mutated human PTEN and expressed the library in Dictyostelium cells. Using live cell imaging, we identified mutations that enhance the association of PTEN with the plasma membrane. These mutations were located in four separate regions, including the phosphatase catalytic site, the calcium-binding region 3 (CBR3) loop, the Cα2 loop and the C-terminal tail phosphorylation site. The phosphatase catalytic site, the CBR3 loop and the Cα2 loop formed the membrane-binding regulatory interface and interacted with the inhibitory phosphorylated C-terminal tail. Furthermore, we showed that membrane recruitment of PTEN is required for PTEN function in cells. Thus, heterologous expression system in Dictyostelium cells provides mechanistic and functional insight into membrane localization of PTEN.
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Li H, Gorfe AA. Aggregation of lipid-anchored full-length H-Ras in lipid bilayers: simulations with the MARTINI force field. PLoS One 2013; 8:e71018. [PMID: 23923044 PMCID: PMC3724741 DOI: 10.1371/journal.pone.0071018] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 06/28/2013] [Indexed: 11/25/2022] Open
Abstract
Lipid-anchored Ras oncoproteins assemble into transient, nano-sized substructures on the plasma membrane. These substructures, called nanoclusters, were proposed to be crucial for high-fidelity signal transmission in cells. However, the molecular basis of Ras nanoclustering is poorly understood. In this work, we used coarse-grained (CG) molecular dynamics simulations to investigate the molecular mechanism by which full-length H-ras proteins form nanoclusters in a model membrane. We chose two different conformations of H-ras that were proposed to represent the active and inactive state of the protein, and a domain-forming model bilayer made up of di16:0-PC (DPPC), di18:2-PC (DLiPC) and cholesterol. We found that, irrespective of the initial conformation, Ras molecules assembled into a single large aggregate. However, the two binding modes, which are characterized by the different orientation of the G-domain with respect to the membrane, differ in dynamics and organization during and after aggregation. Some of these differences involve regions of Ras that are important for effector/modulator binding, which may partly explain observed differences in the ability of active and inactive H-ras nanoclusters to recruit effectors. The simulations also revealed some limitations in the CG force field to study protein assembly in solution, which we discuss in the context of proposed potential avenues of improvement.
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Affiliation(s)
- Hualin Li
- Department of Integrative Biology and Pharmacology, University of Texas Medical School at Houston, Houston, Texas, United States of America
| | - Alemayehu A. Gorfe
- Department of Integrative Biology and Pharmacology, University of Texas Medical School at Houston, Houston, Texas, United States of America
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