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Jani V, Sonavane U, Sawant S. Structural insights into the activation mechanism of phosphoinositide 3-kinase alpha. Comput Biol Chem 2024; 108:107994. [PMID: 38043374 DOI: 10.1016/j.compbiolchem.2023.107994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 11/22/2023] [Accepted: 11/26/2023] [Indexed: 12/05/2023]
Abstract
Phosphoinositide 3-kinases (PI3Ks) are lipid kinases known to regulate important cellular functions by phosphorylating the inositol ring of inositol-phospholipids (PtdIns) at 3' position. The PI3Kα is a heterodimer and the activation of the catalytic subunit (p110α) is regulated by its regulatory subunit (p85α). The current work deals with studying the activation mechanism of the PI3Kα using multi micro-second molecular dynamic simulations. Structural changes involved in activation mechanism is studied by gradually releasing the inhibitory effects of different domains of regulatory subunit namely, n-terminal SH2 (nSH2) and inter SH2 (iSH2). The observation shows that even in the presence of n-terminal and inter SH2 domain (niSH2) of regulatory subunit, the catalytic domain has some intrinsic activation activity and the presence of c-terminal SH2 (cSH2) domain may be required for complete inhibition. The release of nSH2 domain leads to loss of interactions between iSH2 domain (regulatory subunit) and C2 and kinase domain (catalytic subunit). The study shows that early events in the activation mechanism involve the movement of the ABD domain of the catalytic subunit along with the linker region between ABD and RBD region which may lead to movement of ABD closer to the CLobe of the kinase domain. This movement is essentially as it triggers the rearrangement of CLobe especially the catalytic loop and activation loop which bring catalytic important residues closer to ATP and PIP2(phosphatidylinositol-4,5-bisphosphate). Water mediated interaction analysis reveal that water may be playing an important role in the transfer of phosphate from ATP to PIP2. The study shows that initial signal for release of inhibitory effect of the regulatory subunit might be propagated through the linker region between ABD and RBD through allosteric effect to different regions of the protein. These understanding of early events during the activation mechanism may help in the design of better therapeutic targeting PI3K.
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Affiliation(s)
- Vinod Jani
- HPC-M&BA group, Centre for Development of Advanced computing, Pune 411008, India; Bioinformatics centre, SSP University, Pune 411007, India
| | - Uddhavesh Sonavane
- HPC-M&BA group, Centre for Development of Advanced computing, Pune 411008, India.
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2
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Madsen RR, Toker A. PI3K signaling through a biochemical systems lens. J Biol Chem 2023; 299:105224. [PMID: 37673340 PMCID: PMC10570132 DOI: 10.1016/j.jbc.2023.105224] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 08/25/2023] [Accepted: 08/28/2023] [Indexed: 09/08/2023] Open
Abstract
Following 3 decades of extensive research into PI3K signaling, it is now evidently clear that the underlying network does not equate to a simple ON/OFF switch. This is best illustrated by the multifaceted nature of the many diseases associated with aberrant PI3K signaling, including common cancers, metabolic disease, and rare developmental disorders. However, we are still far from a complete understanding of the fundamental control principles that govern the numerous phenotypic outputs that are elicited by activation of this well-characterized biochemical signaling network, downstream of an equally diverse set of extrinsic inputs. At its core, this is a question on the role of PI3K signaling in cellular information processing and decision making. Here, we review the determinants of accurate encoding and decoding of growth factor signals and discuss outstanding questions in the PI3K signal relay network. We emphasize the importance of quantitative biochemistry, in close integration with advances in single-cell time-resolved signaling measurements and mathematical modeling.
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Affiliation(s)
- Ralitsa R Madsen
- MRC-Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom.
| | - Alex Toker
- Department of Pathology and Cancer Center, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.
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3
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Vogt PK, Hart JR, Yang S, Zhou Q, Yang D, Wang MW. Structural and mechanistic insights provided by single particle cryo-EM analysis of phosphoinositide 3-kinase (PI3Kα). Biochim Biophys Acta Rev Cancer 2023; 1878:188947. [PMID: 37394020 PMCID: PMC10530483 DOI: 10.1016/j.bbcan.2023.188947] [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: 05/01/2023] [Revised: 06/27/2023] [Accepted: 06/27/2023] [Indexed: 07/04/2023]
Abstract
Recent cryo-electron microscopic (cryo-EM) investigations have succeeded in the analysis of various structural conformations and functional states of PI3Kα, a dimer consisting of the catalytic subunit p110α and the regulatory subunit p85α of class IA of phosphoinositide 3-kinase. High resolution structures have been obtained of the unliganded and of BYL-719-bound PI3Kα. The latter provides information on excessively flexible domains of p85α that are then further analyzed with nanobodies and CXMS (chemical cross-linking, digestion and mass spectrometry). Analysis of p110α helical and kinase domain mutations reveals mutant-specific features that can be linked to the gain of function in enzymatic and signaling activities.
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Affiliation(s)
- Peter K Vogt
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, United States of America.
| | - Jonathan R Hart
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, United States of America
| | - Su Yang
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, United States of America
| | - Qingtong Zhou
- Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Dehua Yang
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Ming-Wei Wang
- Department of Pharmacology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China; Research Center for Deepsea Bioresources, Sanya 572025, China; Department of Chemistry, School of Science, The University of Tokyo, Tokyo 113-0033, Japan
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4
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Harris NJ, Jenkins ML, Nam SE, Rathinaswamy MK, Parson MA, Ranga-Prasad H, Dalwadi U, Moeller BE, Sheekey E, Hansen SD, Yip CK, Burke JE. Allosteric activation or inhibition of PI3Kγ mediated through conformational changes in the p110γ helical domain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.12.536585. [PMID: 37090531 PMCID: PMC10120615 DOI: 10.1101/2023.04.12.536585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
PI3Kγ is a critical immune signaling enzyme activated downstream of diverse cell surface molecules, including Ras, PKCβ activated by the IgE receptor, and Gβγ subunits released from activated GPCRs. PI3Kγ can form two distinct complexes, with the p110γ catalytic subunit binding to either a p101 or p84 regulatory subunit, with these complexes being differentially activated by upstream stimuli. Here using a combination of Cryo electron microscopy, HDX-MS, and biochemical assays we have identified novel roles of the helical domain of p110γ in regulating lipid kinase activity of distinct PI3Kγ complexes. We defined the molecular basis for how an allosteric inhibitory nanobody potently inhibits kinase activity through rigidifying the helical domain and regulatory motif of the kinase domain. The nanobody did not block either p110γ membrane recruitment or Ras/Gβγ binding, but instead decreased ATP turnover. We also identified that p110γ can be activated by dual PKCβ helical domain phosphorylation leading to partial unfolding of an N-terminal region of the helical domain. PKCβ phosphorylation is selective for p110γ-p84 compared to p110γ-p101, driven by differential dynamics of the helical domain of these different complexes. Nanobody binding prevented PKCβ mediated phosphorylation. Overall, this works shows an unexpected allosteric regulatory role of the helical domain of p110γ that is distinct between p110γ-p84 and p110γ-p101, and reveals how this can be modulated by either phosphorylation or allosteric inhibitory binding partners. This opens possibilities of future allosteric inhibitor development for therapeutic intervention.
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5
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Oncogenic mutations of PIK3CA lead to increased membrane recruitment driven by reorientation of the ABD, p85 and C-terminus. Nat Commun 2023; 14:181. [PMID: 36635288 PMCID: PMC9837058 DOI: 10.1038/s41467-023-35789-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 12/29/2022] [Indexed: 01/14/2023] Open
Abstract
PIK3CA encoding the phosphoinositide 3-kinase (PI3K) p110α catalytic subunit is frequently mutated in cancer, with mutations occurring widely throughout the primary sequence. The full set of mechanisms underlying how PI3Ks are activated by all oncogenic mutations on membranes are unclear. Using a synergy of biochemical assays and hydrogen deuterium exchange mass spectrometry (HDX-MS), we reveal unique regulatory mechanisms underlying PI3K activation. Engagement of p110α on membranes leads to disengagement of the ABD of p110α from the catalytic core, and the C2 domain from the iSH2 domain of the p85 regulatory subunit. PI3K activation also requires reorientation of the p110α C-terminus, with mutations that alter the inhibited conformation of the C-terminus increasing membrane binding. Mutations at the C-terminus (M1043I/L, H1047R, G1049R, and N1068KLKR) activate p110α through distinct mechanisms, with this having important implications for mutant selective inhibitor development. This work reveals unique mechanisms underlying how PI3K is activated by oncogenic mutations, and explains how double mutants can synergistically increase PI3K activity.
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6
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Cryo-EM structures of cancer-specific helical and kinase domain mutations of PI3Kα. Proc Natl Acad Sci U S A 2022; 119:e2215621119. [PMID: 36343266 PMCID: PMC9674216 DOI: 10.1073/pnas.2215621119] [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] [Indexed: 11/09/2022] Open
Abstract
Phosphoinositide 3-kinases (PI3Ks) are a family of lipid kinases that perform multiple and important cellular functions. The protein investigated here belongs to class IA of the PI3Ks; it is a dimer consisting of a catalytic subunit, p110α, and a regulatory subunit, p85α, and is referred to as PI3Kα. The catalytic subunit p110α is frequently mutated in cancer. The mutations induce a gain of function and constitute a driving force in cancer development. About 80% of these mutations lead to single-amino-acid substitutions in one of three sites of p110α: two in the helical domain of the protein (E542K and E545K) and one at the C-terminus of the kinase domain (H1047R). Here, we report the cryo-electron microscopy structures of these mutants in complex with the p110α-specific inhibitor BYL-719. The H1047R mutant rotates its sidechain to a new position and weakens the kα11 activation loop interaction, thereby reducing the inhibitory effect of p85α on p110α. E542K and E545K completely abolish the tight interaction between the helical domain of p110α and the N-terminal SH2 domain of p85α and lead to the disruption of all p85α binding and a dramatic increase in flexibility of the adaptor-binding domain (ABD) in p110α. Yet, the dimerization of PI3Kα is preserved through the ABD-p85α interaction. The local and global structural features induced by these mutations provide molecular insights into the activation of PI3Kα, deepen our understanding of the oncogenic mechanism of this important signaling molecule, and may facilitate the development of mutant-specific inhibitors.
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Kotzampasi DM, Premeti K, Papafotika A, Syropoulou V, Christoforidis S, Cournia Z, Leondaritis G. The orchestrated signaling by PI3Kα and PTEN at the membrane interface. Comput Struct Biotechnol J 2022; 20:5607-5621. [PMID: 36284707 PMCID: PMC9578963 DOI: 10.1016/j.csbj.2022.10.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 10/03/2022] [Accepted: 10/03/2022] [Indexed: 11/16/2022] Open
Abstract
The oncogene PI3Kα and the tumor suppressor PTEN represent two antagonistic enzymatic activities that regulate the interconversion of the phosphoinositide lipids PI(4,5)P2 and PI(3,4,5)P3 in membranes. As such, they are defining components of phosphoinositide-based cellular signaling and membrane trafficking pathways that regulate cell survival, growth, and proliferation, and are often deregulated in cancer. In this review, we highlight aspects of PI3Kα and PTEN interplay at the intersection of signaling and membrane trafficking. We also discuss the mechanisms of PI3Kα- and PTEN- membrane interaction and catalytic activation, which are fundamental for our understanding of the structural and allosteric implications on signaling at the membrane interface and may aid current efforts in pharmacological targeting of these proteins.
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Affiliation(s)
- Danai Maria Kotzampasi
- Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece
- Department of Biology, University of Crete, Heraklion 71500, Greece
| | - Kyriaki Premeti
- Laboratory of Pharmacology, Faculty of Medicine, University of Ioannina, Ioannina 45110, Greece
| | - Alexandra Papafotika
- Laboratory of Biological Chemistry, Faculty of Medicine, School of Health Sciences, University of Ioannina, Ioannina 45110, Greece
- Biomedical Research Institute, Foundation for Research and Technology, Ioannina 45110, Greece
| | - Vasiliki Syropoulou
- Laboratory of Pharmacology, Faculty of Medicine, University of Ioannina, Ioannina 45110, Greece
| | - Savvas Christoforidis
- Laboratory of Biological Chemistry, Faculty of Medicine, School of Health Sciences, University of Ioannina, Ioannina 45110, Greece
- Biomedical Research Institute, Foundation for Research and Technology, Ioannina 45110, Greece
| | - Zoe Cournia
- Biomedical Research Foundation, Academy of Athens, Athens 11527, Greece
| | - George Leondaritis
- Laboratory of Pharmacology, Faculty of Medicine, University of Ioannina, Ioannina 45110, Greece
- Institute of Biosciences, University Research Center of Ioannina, Ioannina 45110, Greece
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8
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Nanobodies and chemical cross-links advance the structural and functional analysis of PI3Kα. Proc Natl Acad Sci U S A 2022; 119:e2210769119. [PMID: 36095215 PMCID: PMC9499577 DOI: 10.1073/pnas.2210769119] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nanobodies and chemical cross-linking were used to gain information on the identity and positions of flexible domains of PI3Kα. The application of chemical cross-linking mass spectrometry (CXMS) facilitated the identification of the p85 domains BH, cSH2, and SH3 as well as their docking positions on the PI3Kα catalytic core. Binding of individual nanobodies to PI3Kα induced activation or inhibition of enzyme activity and caused conformational changes that could be correlated with enzyme function. Binding of nanobody Nb3-126 to the BH domain of p85α substantially improved resolution for parts of the PI3Kα complex, and binding of nanobody Nb3-159 induced a conformation of PI3Kα that is distinct from known PI3Kα structures. The analysis of CXMS data also provided mechanistic insights into the molecular underpinning of the flexibility of PI3Kα.
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9
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Jenkins ML, Ranga-prasad H, Parson MA, Harris NJ, Rathinaswamy MK, Burke JE. Oncogenic mutations of PIK3CAlead to increased membrane recruitment driven by reorientation of the ABD, p85 and C-terminus.. [DOI: 10.1101/2022.04.05.487205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
AbstractPIK3CAencoding the phosphoinositide 3-kinase (PI3K) p110α catalytic subunit is frequently mutated in cancer, with mutations occurring widely throughout the primary sequence. The full set of mechanisms underlying how PI3Ks are activated by all oncogenic mutations on membranes are unclear. Using a synergy of biochemical assays and hydrogen deuterium exchange mass spectrometry (HDX-MS), we reveal unique regulatory mechanisms underlying PI3K activation. Engagement of p110α on membranes leads to disengagement of the ABD of p110α from the catalytic core, and the C2 domain from the iSH2 domain of the p85 regulatory subunit. PI3K activation also requires reorientation of the p110α C-terminus, with mutations that alter the inhibited conformation of the C-terminus increasing membrane binding. Mutations at the C-terminus (M1043I/L, H1047R, G1049R, and N1068KLKR) activate p110α through distinct mechanisms, with this having important implications for mutant selective inhibitor development. This work reveals unique mechanisms underlying how PI3K is activated by oncogenic mutations, and explains how double mutants can synergistically increase PI3K activity.
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10
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Song KW, Edgar KA, Hanan EJ, Hafner M, Oeh J, Merchant M, Sampath D, Nannini MA, Hong R, Phu L, Forrest WF, Stawiski E, Schmidt S, Endres N, Guan J, Wallin JJ, Cheong J, Plise EG, Lewis Phillips GD, Salphati L, Heffron TP, Olivero AG, Malek S, Staben ST, Kirkpatrick DS, Dey A, Friedman LS. RTK-Dependent Inducible Degradation of Mutant PI3Kα Drives GDC-0077 (Inavolisib) Efficacy. Cancer Discov 2022; 12:204-219. [PMID: 34544753 PMCID: PMC9762331 DOI: 10.1158/2159-8290.cd-21-0072] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 07/03/2021] [Accepted: 09/15/2021] [Indexed: 01/07/2023]
Abstract
PIK3CA is one of the most frequently mutated oncogenes; the p110a protein it encodes plays a central role in tumor cell proliferation. Small-molecule inhibitors targeting the PI3K p110a catalytic subunit have entered clinical trials, with early-phase GDC-0077 studies showing antitumor activity and a manageable safety profile in patients with PIK3CA-mutant breast cancer. However, preclinical studies have shown that PI3K pathway inhibition releases negative feedback and activates receptor tyrosine kinase signaling, reengaging the pathway and attenuating drug activity. Here we discover that GDC-0077 and taselisib more potently inhibit mutant PI3K pathway signaling and cell viability through unique HER2-dependent mutant p110a degradation. Both are more effective than other PI3K inhibitors at maintaining prolonged pathway suppression. This study establishes a new strategy for identifying inhibitors that specifically target mutant tumors by selective degradation of the mutant oncoprotein and provide a strong rationale for pursuing PI3Kα degraders in patients with HER2-positive breast cancer. SIGNIFICANCE: The PI3K inhibitors GDC-0077 and taselisib have a unique mechanism of action; both inhibitors lead to degradation of mutant p110a protein. The inhibitors that have the ability to trigger specific degradation of mutant p110a without significant change in wild-type p110a protein may result in improved therapeutic index in PIK3CA-mutant tumors.See related commentary by Vanhaesebroeck et al., p. 20.This article is highlighted in the In This Issue feature, p. 1.
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Affiliation(s)
- Kyung W Song
- Department of Discovery Oncology, Genentech, Inc., South San Francisco, California
| | - Kyle A Edgar
- Department of Discovery Oncology, Genentech, Inc., South San Francisco, California
| | - Emily J Hanan
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, California
| | - Marc Hafner
- Department of Oncology Bioinformatics, Genentech, Inc., South San Francisco, California
| | - Jason Oeh
- Department of Translational Oncology, Genentech, Inc., South San Francisco, California
| | - Mark Merchant
- Department of Translational Oncology, Genentech, Inc., South San Francisco, California
| | - Deepak Sampath
- Department of Translational Oncology, Genentech, Inc., South San Francisco, California
| | - Michelle A Nannini
- Department of Translational Oncology, Genentech, Inc., South San Francisco, California
| | - Rebecca Hong
- Department of Translational Oncology, Genentech, Inc., South San Francisco, California
| | - Lilian Phu
- Department of Microchemistry, Proteomics & Lipidomics, Genentech, Inc., South San Francisco, California
| | - William F Forrest
- Department of Oncology Bioinformatics, Genentech, Inc., South San Francisco, California
| | - Eric Stawiski
- Department of Oncology Bioinformatics, Genentech, Inc., South San Francisco, California
| | - Stephen Schmidt
- Department of Biochemical and Cell Pharmacology, Genentech, Inc., South San Francisco, California
| | - Nicholas Endres
- Department of Biochemical and Cell Pharmacology, Genentech, Inc., South San Francisco, California
| | - Jane Guan
- Department of Discovery Oncology, Genentech, Inc., South San Francisco, California
| | - Jeffrey J Wallin
- Department of Translational Oncology, Genentech, Inc., South San Francisco, California
| | - Jonathan Cheong
- Department of Translational Oncology, Genentech, Inc., South San Francisco, California
| | - Emile G Plise
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc., South San Francisco, California
| | | | - Laurent Salphati
- Department of Drug Metabolism and Pharmacokinetics, Genentech, Inc., South San Francisco, California
| | - Timothy P Heffron
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, California
| | - Alan G Olivero
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, California
| | - Shiva Malek
- Department of Discovery Oncology, Genentech, Inc., South San Francisco, California
| | - Steven T Staben
- Department of Discovery Chemistry, Genentech, Inc., South San Francisco, California
| | - Donald S Kirkpatrick
- Department of Microchemistry, Proteomics & Lipidomics, Genentech, Inc., South San Francisco, California
| | - Anwesha Dey
- Department of Discovery Oncology, Genentech, Inc., South San Francisco, California.
| | - Lori S Friedman
- Department of Translational Oncology, Genentech, Inc., South San Francisco, California.
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Cryo-EM structures of PI3Kα reveal conformational changes during inhibition and activation. Proc Natl Acad Sci U S A 2021; 118:2109327118. [PMID: 34725156 PMCID: PMC8609346 DOI: 10.1073/pnas.2109327118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2021] [Indexed: 02/07/2023] Open
Abstract
Phosphoinositide 3-kinases (PI3Ks) are of critical importance in cell signaling and can function as drivers of disease. Information on the PI3K structure is essential for an understanding of the function of these proteins and for the identification of specific and effective small-molecule inhibitors. Here we present a single-particle cryo-electron microscopy (cryo-EM) analysis of PI3Kα, the dimer consisting of the p110α catalytic subunit bound to the p85α regulatory subunit. We investigated three conformational states of PI3Kα: the unbound dimer, the dimer bound to the isoform-specific inhibitor BYL-719, and the dimer associated with an activating phosphopeptide. Each of these conformations reveals specific structural features that provide insights into conformation-associated functions. Phosphoinositide 3-kinases (PI3Ks) are lipid kinases essential for growth and metabolism. Their aberrant activation is associated with many types of cancers. Here we used single-particle cryoelectron microscopy (cryo-EM) to determine three distinct conformations of full-length PI3Kα (p110α–p85α): the unliganded heterodimer PI3Kα, PI3Kα bound to the p110α-specific inhibitor BYL-719, and PI3Kα exposed to an activating phosphopeptide. The cryo-EM structures of unbound and of BYL-719–bound PI3Kα are in general accord with published crystal structures. Local deviations are presented and discussed. BYL-719 stabilizes the structure of PI3Kα, but three regions of low-resolution extra density remain and are provisionally assigned to the cSH2, BH, and SH3 domains of p85. One of the extra density regions is in contact with the kinase domain blocking access to the catalytic site. This conformational change indicates that the effects of BYL-719 on PI3Kα activity extend beyond competition with adenosine triphosphate (ATP). In unliganded PI3Kα, the DFG motif occurs in the “in” and “out” positions. In BYL-719–bound PI3Kα, only the DFG-in position, corresponding to the active conformation of the kinase, was observed. The phosphopeptide-bound structure of PI3Kα is composed of a stable core resolved at 3.8 Å. It contains all p110α domains except the adaptor-binding domain (ABD). The p85α domains, linked to the core through the ABD, are no longer resolved, implying that the phosphopeptide activates PI3Kα by fully releasing the niSH2 domain from binding to p110α. The structures presented here show the basal form of the full-length PI3Kα dimer and document conformational changes related to the activated and inhibited states.
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12
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Gordon MT, Ziemba BP, Falke JJ. Single-molecule studies reveal regulatory interactions between master kinases PDK1, AKT1, and PKC. Biophys J 2021; 120:5657-5673. [PMID: 34673053 DOI: 10.1016/j.bpj.2021.10.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 09/30/2021] [Accepted: 10/13/2021] [Indexed: 12/26/2022] Open
Abstract
Leukocyte migration is controlled by a leading-edge chemosensory pathway that generates the regulatory lipid phosphatidylinositol-3,4,5-trisphosphate (PIP3), a growth signal, thereby driving leading-edge expansion up attractant gradients toward sites of infection, inflammation, or tissue damage. PIP3 also serves as an important growth signal in growing cells and oncogenesis. The kinases PDK1, AKT1 or PKB, and PKCα are key components of a plasma-membrane-based PIP3 and Ca2+ signaling circuit that regulates these processes. PDK1 and AKT1 are recruited to the membrane by PIP3, whereas PKCα is recruited to the membrane by Ca2+. All three of these master kinases phosphoregulate an array of protein targets. For example, PDK1 activates AKT1, PKCα, and other AGC kinases by phosphorylation at key sites. PDK1 is believed to form PDK1-AKT1 and PDK1-PKCα heterodimers stabilized by a PDK1-interacting fragment (PIF) interaction between the PDK1 PIF pocket and the PIF motif of the AGC binding partner. Here, we present the first, to our knowledge, single-molecule studies of full-length PDK1 and AKT1 on target membrane surfaces, as well as their interaction with full-length PKCα. These studies directly detect membrane-bound PDK1-AKT1 and PDK1-PKCα heterodimers stabilized by PIF interactions formed at physiological ligand concentrations. PKCα exhibits eightfold higher PDK1 affinity than AKT1 and can competitively displace AKT1 from PDK1-AKT1 heterodimers. Ensemble activity measurements under matched conditions reveal that PDK1 activates AKT1 via a cis mechanism by phosphorylating an AKT1 molecule in the same PDK1-AKT1 heterodimer, whereas PKCα acts as a competitive inhibitor of this phosphoactivation reaction by displacing AKT1 from PDK1. Overall, the findings provide insights into the binding and regulatory interactions of the three master kinases on their target membrane and suggest that a recently described tumor suppressor activity of PKC isoforms may arise from its ability to downregulate PDK1-AKT1 phosphoactivation in the PIP3-PDK1-AKT1-mTOR pathway linked to cell growth and oncogenesis.
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Affiliation(s)
- Moshe T Gordon
- Molecular Biophysics Program and Department of Biochemistry, University of Colorado, Boulder, Colorado
| | - Brian P Ziemba
- Molecular Biophysics Program and Department of Biochemistry, University of Colorado, Boulder, Colorado
| | - Joseph J Falke
- Molecular Biophysics Program and Department of Biochemistry, University of Colorado, Boulder, Colorado.
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13
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Luff DH, Wojdyla K, Oxley D, Chessa T, Hudson K, Hawkins PT, Stephens LR, Barry ST, Okkenhaug K. PI3Kδ Forms Distinct Multiprotein Complexes at the TCR Signalosome in Naïve and Differentiated CD4 + T Cells. Front Immunol 2021; 12:631271. [PMID: 33763075 PMCID: PMC7982423 DOI: 10.3389/fimmu.2021.631271] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 02/02/2021] [Indexed: 11/14/2022] Open
Abstract
Phosphoinositide 3-kinases (PI3Ks) play a central role in adaptive immunity by transducing signals from the T cell antigen receptor (TCR) via production of PIP3. PI3Kδ is a heterodimer composed of a p110δ catalytic subunit associated with a p85α or p85β regulatory subunit and is preferentially engaged by the TCR upon T cell activation. The molecular mechanisms leading to PI3Kδ recruitment and activation at the TCR signalosome remain unclear. In this study, we have used quantitative mass spectrometry, biochemical approaches and CRISPR-Cas9 gene editing to uncover the p110δ interactome in primary CD4+ T cells. Moreover, we have determined how the PI3Kδ interactome changes upon the differentiation of small naïve T cells into T cell blasts expanded in the presence of IL-2. Our interactomic analyses identified multiple constitutive and inducible PI3Kδ-interacting proteins, some of which were common to naïve and previously-activated T cells. Our data reveals that PI3Kδ rapidly interacts with as many as seven adaptor proteins upon TCR engagement, including the Gab-family proteins, GAB2 and GAB3, a CD5-CBL signalosome and the transmembrane proteins ICOS and TRIM. Our results also suggest that PI3Kδ pre-forms complexes with the adaptors SH3KBP1 and CRKL in resting cells that could facilitate the localization and activation of p110δ at the plasma membrane by forming ternary complexes during early TCR signalling. Furthermore, we identify interactions that were not previously known to occur in CD4+ T cells, involving BCAP, GAB3, IQGAP3 and JAML. We used CRISPR-Cas9-mediated gene knockout in primary T cells to confirm that BCAP is a positive regulator of PI3K-AKT signalling in CD4+ T cell blasts. Overall, our results provide evidence for a large protein network that regulates the recruitment and activation of PI3Kδ in T cells. Finally, this work shows how the PI3Kδ interactome is remodeled as CD4+ T cells differentiate from naïve T cells to activated T cell blasts. These activated T cells upregulate additional PI3Kδ adaptor proteins, including BCAP, GAB2, IQGAP3 and ICOS. This rewiring of TCR-PI3K signalling that occurs upon T cell differentiation may serve to reduce the threshold of activation and diversify the inputs for the PI3K pathway in effector T cells.
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Affiliation(s)
- Daisy H Luff
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, United Kingdom
| | - Katarzyna Wojdyla
- Mass Spectrometry Facility, The Babraham Institute, Cambridge, United Kingdom.,Signalling Programme, The Babraham Institute, Cambridge, United Kingdom
| | - David Oxley
- Mass Spectrometry Facility, The Babraham Institute, Cambridge, United Kingdom
| | - Tamara Chessa
- Signalling Programme, The Babraham Institute, Cambridge, United Kingdom
| | - Kevin Hudson
- Bioscience, Oncology R&D, AstraZeneca, Cambridge, United Kingdom
| | - Phillip T Hawkins
- Signalling Programme, The Babraham Institute, Cambridge, United Kingdom
| | - Len R Stephens
- Signalling Programme, The Babraham Institute, Cambridge, United Kingdom
| | - Simon T Barry
- Bioscience, Oncology R&D, AstraZeneca, Cambridge, United Kingdom
| | - Klaus Okkenhaug
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
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14
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Rathinaswamy MK, Gaieb Z, Fleming KD, Borsari C, Harris NJ, Moeller BE, Wymann MP, Amaro RE, Burke JE. Disease-related mutations in PI3Kγ disrupt regulatory C-terminal dynamics and reveal a path to selective inhibitors. eLife 2021; 10:e64691. [PMID: 33661099 PMCID: PMC7955810 DOI: 10.7554/elife.64691] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Accepted: 03/03/2021] [Indexed: 12/11/2022] Open
Abstract
Class I Phosphoinositide 3-kinases (PI3Ks) are master regulators of cellular functions, with the class IB PI3K catalytic subunit (p110γ) playing key roles in immune signalling. p110γ is a key factor in inflammatory diseases and has been identified as a therapeutic target for cancers due to its immunomodulatory role. Using a combined biochemical/biophysical approach, we have revealed insight into regulation of kinase activity, specifically defining how immunodeficiency and oncogenic mutations of R1021 in the C-terminus can inactivate or activate enzyme activity. Screening of inhibitors using HDX-MS revealed that activation loop-binding inhibitors induce allosteric conformational changes that mimic those in the R1021C mutant. Structural analysis of advanced PI3K inhibitors in clinical development revealed novel binding pockets that can be exploited for further therapeutic development. Overall, this work provides unique insights into regulatory mechanisms that control PI3Kγ kinase activity and shows a framework for the design of PI3K isoform and mutant selective inhibitors.
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Affiliation(s)
- Manoj K Rathinaswamy
- Department of Biochemistry and Microbiology, University of VictoriaVictoriaCanada
| | - Zied Gaieb
- Department of Chemistry and Biochemistry, University of California San DiegoSan DiegoUnited States
| | - Kaelin D Fleming
- Department of Biochemistry and Microbiology, University of VictoriaVictoriaCanada
| | - Chiara Borsari
- University of Basel, Department of BiomedicineBaselSwitzerland
| | - Noah J Harris
- Department of Biochemistry and Microbiology, University of VictoriaVictoriaCanada
| | - Brandon E Moeller
- Department of Biochemistry and Microbiology, University of VictoriaVictoriaCanada
| | | | - Rommie E Amaro
- Department of Chemistry and Biochemistry, University of California San DiegoSan DiegoUnited States
| | - John E Burke
- Department of Biochemistry and Microbiology, University of VictoriaVictoriaCanada
- Department of Biochemistry and Molecular Biology, The University of British ColumbiaVancouverCanada
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15
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Akbari Dilmaghani N, Safaroghli-Azar A, Pourbagheri-Sigaroodi A, Bashash D. The PI3K/Akt/mTORC signaling axis in head and neck squamous cell carcinoma: Possibilities for therapeutic interventions either as single agents or in combination with conventional therapies. IUBMB Life 2021; 73:618-642. [PMID: 33476088 DOI: 10.1002/iub.2446] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 12/24/2020] [Indexed: 01/08/2023]
Abstract
The latest advances in the sequencing methods in head and neck squamous cell carcinoma (HNSCC) tissues have revolutionized our understanding of the disease by taking off the veil from the most frequent genetic alterations in the components of the oncogenic pathways. Among all the identified alterations, aberrancies in the genes attributed to the phosphoinositide 3-kinases (PI3K) axis have attracted special attention as they were altered in more than 90% of the tissues isolated from HNSCC patients. In fact, the association between these aberrancies and the increased risk of cancer metastasis suggested this axis as an "Achilles Heel" of HNSCC, which may be therapeutically targeted. The results of the clinical trials investigating the therapeutic potential of the inhibitors targeting the components of the PI3K axis in the treatment of HNSCC patients, either alone or in a combined-modal strategy, opened a new chapter in the treatment strategy of this malignancy. The present study aimed to review the importance of the PI3K axis in the pathogenesis of HNSCC and also provide a piece of information about the breakthroughs and challenges of PI3K inhibitors in the therapeutic strategies of the disease.
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Affiliation(s)
- Nader Akbari Dilmaghani
- Hearing Disorders Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.,Department of Otolaryngology, Head and Neck Surgery, Loghman Hakim Educational Hospital, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ava Safaroghli-Azar
- Department of Hematology and Blood Banking, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Atieh Pourbagheri-Sigaroodi
- Department of Hematology and Blood Banking, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Davood Bashash
- Department of Hematology and Blood Banking, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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16
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The G-Protein Rab5A Activates VPS34 Complex II, a Class III PI3K, by a Dual Regulatory Mechanism. Biophys J 2020; 119:2205-2218. [PMID: 33137306 DOI: 10.1016/j.bpj.2020.10.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 10/04/2020] [Accepted: 10/07/2020] [Indexed: 02/07/2023] Open
Abstract
VPS34 complex II (VPS34CII) is a 386-kDa assembly of the lipid kinase subunit VPS34 and three regulatory subunits that altogether function as a prototypical class III phosphatidylinositol-3-kinase (PI3K). When the active VPS34CII complex is docked to the cytoplasmic surface of endosomal membranes, it phosphorylates its substrate lipid (phosphatidylinositol, PI) to generate the essential signaling lipid phosphatidylinositol-3-phosphate (PI3P). In turn, PI3P recruits an array of signaling proteins containing PI3P-specific targeting domains (including FYVE, PX, and PROPPINS) to the membrane surface, where they initiate key cell processes. In endocytosis and early endosome development, net VPS34CII-catalyzed PI3P production is greatly amplified by Rab5A, a small G protein of the Ras GTPase superfamily. Moreover, VPS34CII and Rab5A are each strongly linked to multiple human diseases. Thus, a molecular understanding of the mechanism by which Rab5A activates lipid kinase activity will have broad impacts in both signaling biology and medicine. Two general mechanistic models have been proposed for small G protein activation of PI3K lipid kinases. 1) In the membrane recruitment mechanism, G protein association increases the density of active kinase on the membrane. And 2) in the allosteric activation mechanism, G protein allosterically triggers an increase in the specific activity (turnover rate) of the membrane-bound kinase molecule. This study employs an in vitro single-molecule approach to elucidate the mechanism of GTP-Rab5A-associated VPS34CII kinase activation in a reconstituted GTP-Rab5A-VPS34CII-PI3P-PX signaling pathway on a target membrane surface. The findings reveal that both membrane recruitment and allosteric mechanisms make important contributions to the large increase in VPS34CII kinase activity and PI3P production triggered by membrane-anchored GTP-Rab5A. Notably, under near-physiological conditions in the absence of other activators, membrane-anchored GTP-Rab5A provides strong, virtually binary on-off switching and is required for VPS34CII membrane binding and PI3P production.
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17
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Beziau A, Brand D, Piver E. The Role of Phosphatidylinositol Phosphate Kinases during Viral Infection. Viruses 2020; 12:v12101124. [PMID: 33022924 PMCID: PMC7599803 DOI: 10.3390/v12101124] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 09/27/2020] [Accepted: 09/29/2020] [Indexed: 12/11/2022] Open
Abstract
Phosphoinositides account for only a small proportion of cellular phospholipids, but have long been known to play an important role in diverse cellular processes, such as cell signaling, the establishment of organelle identity, and the regulation of cytoskeleton and membrane dynamics. As expected, given their pleiotropic regulatory functions, they have key functions in viral replication. The spatial restriction and steady-state levels of each phosphoinositide depend primarily on the concerted action of specific phosphoinositide kinases and phosphatases. This review focuses on a number of remarkable examples of viral strategies involving phosphoinositide kinases to ensure effective viral replication.
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Affiliation(s)
- Anne Beziau
- INSERM U1259, University of Tours, 37000 Tours, France
| | - Denys Brand
- INSERM U1259, University of Tours, 37000 Tours, France
- Virology Laboratory, Tours University Hospital, 3700 Tours, France
| | - Eric Piver
- INSERM U1259, University of Tours, 37000 Tours, France
- Biochemistry and Molecular Biology, Tours University Hospital, 3700 Tours, France
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18
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Katan M, Cockcroft S. Phosphatidylinositol(4,5)bisphosphate: diverse functions at the plasma membrane. Essays Biochem 2020; 64:513-531. [PMID: 32844214 PMCID: PMC7517351 DOI: 10.1042/ebc20200041] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/25/2020] [Accepted: 07/29/2020] [Indexed: 12/20/2022]
Abstract
Phosphatidylinositol(4,5) bisphosphate (PI(4,5)P2) has become a major focus in biochemistry, cell biology and physiology owing to its diverse functions at the plasma membrane. As a result, the functions of PI(4,5)P2 can be explored in two separate and distinct roles - as a substrate for phospholipase C (PLC) and phosphoinositide 3-kinase (PI3K) and as a primary messenger, each having unique properties. Thus PI(4,5)P2 makes contributions in both signal transduction and cellular processes including actin cytoskeleton dynamics, membrane dynamics and ion channel regulation. Signalling through plasma membrane G-protein coupled receptors (GPCRs), receptor tyrosine kinases (RTKs) and immune receptors all use PI(4,5)P2 as a substrate to make second messengers. Activation of PI3K generates PI(3,4,5)P3 (phosphatidylinositol(3,4,5)trisphosphate), a lipid that recruits a plethora of proteins with pleckstrin homology (PH) domains to the plasma membrane to regulate multiple aspects of cellular function. In contrast, PLC activation results in the hydrolysis of PI(4,5)P2 to generate the second messengers, diacylglycerol (DAG), an activator of protein kinase C and inositol(1,4,5)trisphosphate (IP3/I(1,4,5)P3) which facilitates an increase in intracellular Ca2+. Decreases in PI(4,5)P2 by PLC also impact on functions that are dependent on the intact lipid and therefore endocytosis, actin dynamics and ion channel regulation are subject to control. Spatial organisation of PI(4,5)P2 in nanodomains at the membrane allows for these multiple processes to occur concurrently.
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Affiliation(s)
- Matilda Katan
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, U.K
| | - Shamshad Cockcroft
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, 21 University Street, London WC1E 6JJ, U.K
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19
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Translation Regulation by eIF2α Phosphorylation and mTORC1 Signaling Pathways in Non-Communicable Diseases (NCDs). Int J Mol Sci 2020; 21:ijms21155301. [PMID: 32722591 PMCID: PMC7432514 DOI: 10.3390/ijms21155301] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/20/2020] [Accepted: 07/22/2020] [Indexed: 02/07/2023] Open
Abstract
Non-communicable diseases (NCDs) are medical conditions that, by definition, are non-infectious and non-transmissible among people. Much of current NCDs are generally due to genetic, behavioral, and metabolic risk factors that often include excessive alcohol consumption, smoking, obesity, and untreated elevated blood pressure, and share many common signal transduction pathways. Alterations in cell and physiological signaling and transcriptional control pathways have been well studied in several human NCDs, but these same pathways also regulate expression and function of the protein synthetic machinery and mRNA translation which have been less well investigated. Alterations in expression of specific translation factors, and disruption of canonical mRNA translational regulation, both contribute to the pathology of many NCDs. The two most common pathological alterations that contribute to NCDs discussed in this review will be the regulation of eukaryotic initiation factor 2 (eIF2) by the integrated stress response (ISR) and the mammalian target of rapamycin complex 1 (mTORC1) pathways. Both pathways integrally connect mRNA translation activity to external and internal physiological stimuli. Here, we review the role of ISR control of eIF2 activity and mTORC1 control of cap-mediated mRNA translation in some common NCDs, including Alzheimer’s disease, Parkinson’s disease, stroke, diabetes mellitus, liver cirrhosis, chronic obstructive pulmonary disease (COPD), and cardiac diseases. Our goal is to provide insights that further the understanding as to the important role of translational regulation in the pathogenesis of these diseases.
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20
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Galdadas I, Gervasio FL, Cournia Z. Unravelling the effect of the E545K mutation on PI3Kα kinase. Chem Sci 2020; 11:3511-3515. [PMID: 34703536 PMCID: PMC8493679 DOI: 10.1039/c9sc05903b] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 02/26/2020] [Indexed: 12/11/2022] Open
Abstract
PI3Kα controls several cellular processes and its aberrant signalling is implicated in tumorigenesis. One of its hotspot mutations, E545K, increases PI3Kα lipid kinase activity, but its mode of action is only partially understood. Here, we perform biased and unbiased molecular dynamics simulations of PI3Kα and uncover, for the first time, the free energy landscape of the E545K PI3Kα mutant. We reveal the mechanism by which E545K leads to PI3Kα activation in atomic-level detail, which is considerably more complex than previously thought.
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Affiliation(s)
- Ioannis Galdadas
- Department of Chemistry, University College London London WC1E 6BT UK
| | - Francesco Luigi Gervasio
- Department of Chemistry, University College London London WC1E 6BT UK
- Institute of Structural and Molecular Biology, University College London London WC1E 6BT UK
- Pharmaceutical Sciences, University of Geneva Geneva CH-1211 Switzerland
| | - Zoe Cournia
- Biomedical Research Foundation, Academy of Athens Athens 11527 Greece
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21
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Durrant TN, Hers I. PI3K inhibitors in thrombosis and cardiovascular disease. Clin Transl Med 2020; 9:8. [PMID: 32002690 PMCID: PMC6992830 DOI: 10.1186/s40169-020-0261-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 01/13/2020] [Indexed: 12/15/2022] Open
Abstract
Phosphoinositide 3-kinases (PI3Ks) are lipid kinases that regulate important intracellular signalling and vesicle trafficking events via the generation of 3-phosphoinositides. Comprising eight core isoforms across three classes, the PI3K family displays broad expression and function throughout mammalian tissues, and the (patho)physiological roles of these enzymes in the cardiovascular system present the PI3Ks as potential therapeutic targets in settings such as thrombosis, atherosclerosis and heart failure. This review will discuss the PI3K enzymes and their roles in cardiovascular physiology and disease, with a particular focus on platelet function and thrombosis. The current progress and future potential of targeting the PI3K enzymes for therapeutic benefit in cardiovascular disease will be considered, while the challenges of developing drugs against these master cellular regulators will be discussed.
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Affiliation(s)
- Tom N Durrant
- Department of Chemistry, University of Oxford, Oxford, OX1 3QZ, UK.
| | - Ingeborg Hers
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, UK.
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22
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Defining How Oncogenic and Developmental Mutations of PIK3R1 Alter the Regulation of Class IA Phosphoinositide 3-Kinases. Structure 2019; 28:145-156.e5. [PMID: 31831213 DOI: 10.1016/j.str.2019.11.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 09/27/2019] [Accepted: 11/15/2019] [Indexed: 11/21/2022]
Abstract
The class I phosphoinositide 3-kinases (PI3Ks) are key signaling enzymes composed of a heterodimer of a p110 catalytic subunit and a p85 regulatory subunit, with PI3K mutations being causative of multiple human diseases including cancer, primary immunodeficiencies, and developmental disorders. Mutations in the p85α regulatory subunit encoded by PIK3R1 can both activate PI3K through oncogenic truncations in the iSH2 domain, or inhibit PI3K through developmental disorder mutations in the cSH2 domain. Using a combined biochemical and hydrogen deuterium exchange mass spectrometry approach we have defined the molecular basis for how these mutations alter the activity of p110α/p110δ catalytic subunits. We find that the oncogenic Q572∗ truncation of PIK3R1 disrupts all p85-inhibitory inputs, with p110α being hyper-activated compared with p110δ. In addition, we find that the R649W mutation in the cSH2 of PIK3R1 decreases sensitivity to activation by receptor tyrosine kinases. This work reveals unique insight into isoform-specific regulation of p110s by p85α.
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23
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Rathinaswamy MK, Burke JE. Class I phosphoinositide 3-kinase (PI3K) regulatory subunits and their roles in signaling and disease. Adv Biol Regul 2019; 75:100657. [PMID: 31611073 DOI: 10.1016/j.jbior.2019.100657] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 09/23/2019] [Accepted: 09/25/2019] [Indexed: 02/06/2023]
Abstract
The Class I phosphoinositide 3-kinases (PI3Ks) are a group of heterodimeric lipid kinases that regulate crucial cellular processes including proliferation, survival, growth, and metabolism. The diversity in functions controlled by the various catalytic isoforms (p110α, p110β, p110δ, and p110γ) depends on their abilities to be activated by distinct stimuli such as receptor tyrosine kinases (RTKs), G-protein coupled receptors (GPCRs), and the Ras family of small G-proteins. A major factor determining the ability of each p110 enzyme to be activated is the presence of regulatory binding partners. Given the overwhelming evidence for the involvement of PI3Ks in diseases such as cancer, inflammation, immunodeficiency and diabetes, an understanding of how these regulatory proteins influence PI3K function is essential. This article highlights research deciphering the role of regulatory subunits in PI3K signaling and their involvement in human disease.
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Affiliation(s)
- Manoj K Rathinaswamy
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, V8W 2Y2, Canada
| | - John E Burke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, V8W 2Y2, Canada.
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24
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Hageman TS, Weis DD. Reliable Identification of Significant Differences in Differential Hydrogen Exchange-Mass Spectrometry Measurements Using a Hybrid Significance Testing Approach. Anal Chem 2019; 91:8008-8016. [DOI: 10.1021/acs.analchem.9b01325] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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25
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Review: Precision medicine and driver mutations: Computational methods, functional assays and conformational principles for interpreting cancer drivers. PLoS Comput Biol 2019; 15:e1006658. [PMID: 30921324 PMCID: PMC6438456 DOI: 10.1371/journal.pcbi.1006658] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
At the root of the so-called precision medicine or precision oncology, which is our focus here, is the hypothesis that cancer treatment would be considerably better if therapies were guided by a tumor’s genomic alterations. This hypothesis has sparked major initiatives focusing on whole-genome and/or exome sequencing, creation of large databases, and developing tools for their statistical analyses—all aspiring to identify actionable alterations, and thus molecular targets, in a patient. At the center of the massive amount of collected sequence data is their interpretations that largely rest on statistical analysis and phenotypic observations. Statistics is vital, because it guides identification of cancer-driving alterations. However, statistics of mutations do not identify a change in protein conformation; therefore, it may not define sufficiently accurate actionable mutations, neglecting those that are rare. Among the many thematic overviews of precision oncology, this review innovates by further comprehensively including precision pharmacology, and within this framework, articulating its protein structural landscape and consequences to cellular signaling pathways. It provides the underlying physicochemical basis, thereby also opening the door to a broader community.
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26
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Vallejo-Díaz J, Chagoyen M, Olazabal-Morán M, González-García A, Carrera AC. The Opposing Roles of PIK3R1/p85α and PIK3R2/p85β in Cancer. Trends Cancer 2019; 5:233-244. [PMID: 30961830 DOI: 10.1016/j.trecan.2019.02.009] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 02/11/2019] [Accepted: 02/15/2019] [Indexed: 01/04/2023]
Abstract
Dysregulation of the PI3K/PTEN pathway is a frequent event in cancer, and PIK3CA and PTEN are the most commonly mutated genes after TP53. PIK3R1 is the predominant regulatory isoform of PI3K. PIK3R2 is an ubiquitous isoform that has been so far overlooked, but data from The Cancer Genome Atlas shows that increased expression of PIK3R2 is also frequent in cancer. In contrast to PIK3R1, which is a tumor-suppressor gene, PIK3R2 is an oncogene. We review here the opposing roles of PIK3R1 and PIK3R2 in cancer, the regulatory mechanisms that control PIK3R2 expression, and emerging therapeutic approaches targeting PIK3R2.
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Affiliation(s)
- Jesús Vallejo-Díaz
- Department of Immunology and Oncology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid, Cantoblanco, Madrid E-28049, Spain
| | - Monica Chagoyen
- Department of Systems Biology, Centro Nacional de Biotecnología, CSIC, Universidad Autónoma de Madrid, Cantoblanco, Madrid E-28049, Spain
| | - Manuel Olazabal-Morán
- Department of Immunology and Oncology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid, Cantoblanco, Madrid E-28049, Spain
| | - Ana González-García
- Department of Immunology and Oncology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid, Cantoblanco, Madrid E-28049, Spain
| | - Ana Clara Carrera
- Department of Immunology and Oncology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid, Cantoblanco, Madrid E-28049, Spain.
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27
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Bresnick AR, Backer JM. PI3Kβ-A Versatile Transducer for GPCR, RTK, and Small GTPase Signaling. Endocrinology 2019; 160:536-555. [PMID: 30601996 PMCID: PMC6375709 DOI: 10.1210/en.2018-00843] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 12/20/2018] [Indexed: 12/17/2022]
Abstract
The phosphoinositide 3-kinase (PI3K) family includes eight distinct catalytic subunits and seven regulatory subunits. Only two PI3Ks are directly regulated downstream from G protein-coupled receptors (GPCRs): the class I enzymes PI3Kβ and PI3Kγ. Both enzymes produce phosphatidylinositol 3,4,5-trisposphate in vivo and are regulated by both heterotrimeric G proteins and small GTPases from the Ras or Rho families. However, PI3Kβ is also regulated by direct interactions with receptor tyrosine kinases (RTKs) and their tyrosine phosphorylated substrates, and similar to the class II and III PI3Ks, it binds activated Rab5. The unusually complex regulation of PI3Kβ by small and trimeric G proteins and RTKs leads to a rich landscape of signaling responses at the cellular and organismic levels. This review focuses first on the regulation of PI3Kβ activity in vitro and in cells, and then summarizes the biology of PI3Kβ signaling in distinct tissues and in human disease.
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Affiliation(s)
- Anne R Bresnick
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York
| | - Jonathan M Backer
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York
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28
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Abstract
Since I started doing scientific research, I've been fascinated by the interplay of protein structure and dynamics and how they together mediate protein function. A particular area of interest has been in understanding the mechanistic basis of how lipid-signaling enzymes function on membrane surfaces. In this award lecture article, I will describe my laboratory's studies on the structure and dynamics of lipid-signaling enzymes on membrane surfaces. This is important, as many lipid-signaling enzymes are regulated through dynamic regulatory mechanisms that control their enzymatic activity. This article will discuss my continued enthusiasm in using a synergistic application of hydrogen-deuterium exchange MS (HDX-MS) with other structural biology techniques to probe the mechanistic basis for how membrane-localized signaling enzymes are regulated and how these approaches can be used to understand how they are misregulated in disease. I will discuss specific examples of how we have used HDX-MS to study phosphoinositide kinases and the protein kinase Akt. An important focus will be on a description of how HDX-MS can be used as a powerful tool to optimize the design of constructs for X-ray crystallography and EM. The use of a diverse toolbox of biophysical methods has revealed novel insight into the complex and varied regulatory networks that control the function of lipid-signaling enzymes and enabled unique insight into the mechanics of membrane recruitment.
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Affiliation(s)
- John E Burke
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada
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Class I Phosphoinositide 3-Kinase PIK3CA/p110α and PIK3CB/p110β Isoforms in Endometrial Cancer. Int J Mol Sci 2018; 19:ijms19123931. [PMID: 30544563 PMCID: PMC6321576 DOI: 10.3390/ijms19123931] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 11/26/2018] [Accepted: 12/03/2018] [Indexed: 12/24/2022] Open
Abstract
The phosphoinositide 3-kinase (PI3K) signalling pathway is highly dysregulated in cancer, leading to elevated PI3K signalling and altered cellular processes that contribute to tumour development. The pathway is normally orchestrated by class I PI3K enzymes and negatively regulated by the phosphatase and tensin homologue, PTEN. Endometrial carcinomas harbour frequent alterations in components of the pathway, including changes in gene copy number and mutations, in particular in the oncogene PIK3CA, the gene encoding the PI3K catalytic subunit p110α, and the tumour suppressor PTEN. PIK3CB, encoding the other ubiquitously expressed class I isoform p110β, is less frequently altered but the few mutations identified to date are oncogenic. This isoform has received more research interest in recent years, particularly since PTEN-deficient tumours were found to be reliant on p110β activity to sustain transformation. In this review, we describe the current understanding of the common and distinct biochemical properties of the p110α and p110β isoforms, summarise their mutations and highlight how they are targeted in clinical trials in endometrial cancer.
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30
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Bavelloni A, Focaccia E, Piazzi M, Orsini A, Ramazzotti G, Cocco L, Blalock W, Faenza I. Therapeutic potential of nvp‐bkm120 in human osteosarcomas cells. J Cell Physiol 2018; 234:10907-10917. [DOI: 10.1002/jcp.27911] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 10/24/2018] [Indexed: 12/25/2022]
Affiliation(s)
- Alberto Bavelloni
- Laboratory of Musculoskeletal Cell Biology, IRCCS Istituto Ortopedico Rizzoli Bologna Italy
| | - Enrico Focaccia
- CNR Institute of Molecular Genetics, Unit of Bologna Bologna Italy
| | - Manuela Piazzi
- Laboratory of Musculoskeletal Cell Biology, IRCCS Istituto Ortopedico Rizzoli Bologna Italy
- CNR Institute of Molecular Genetics, Unit of Bologna Bologna Italy
| | - Arianna Orsini
- Department of Biomedical Sciences University of Bologna Bologna Italy
| | - Giulia Ramazzotti
- Department of Biomedical Sciences University of Bologna Bologna Italy
| | - Lucio Cocco
- Department of Biomedical Sciences University of Bologna Bologna Italy
| | - William Blalock
- Laboratory of Musculoskeletal Cell Biology, IRCCS Istituto Ortopedico Rizzoli Bologna Italy
- CNR Institute of Molecular Genetics, Unit of Bologna Bologna Italy
| | - Irene Faenza
- Department of Biomedical Sciences University of Bologna Bologna Italy
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31
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Tsolakos N, Durrant TN, Chessa T, Suire SM, Oxley D, Kulkarni S, Downward J, Perisic O, Williams RL, Stephens L, Hawkins PT. Quantitation of class IA PI3Ks in mice reveals p110-free-p85s and isoform-selective subunit associations and recruitment to receptors. Proc Natl Acad Sci U S A 2018; 115:12176-12181. [PMID: 30442661 PMCID: PMC6275495 DOI: 10.1073/pnas.1803446115] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Class IA PI3Ks have many roles in health and disease. The rules that govern intersubunit and receptor associations, however, remain unclear. We engineered mouse lines in which individual endogenous class IA PI3K subunits were C-terminally tagged with 17aa that could be biotinylated in vivo. Using these tools we quantified PI3K subunits in streptavidin or PDGFR pull-downs and cell lysates. This revealed that p85α and β bound equivalently to p110α or p110β but p85α bound preferentially to p110δ. p85s were found in molar-excess over p110s in a number of contexts including MEFs (p85β, 20%) and liver (p85α, 30%). In serum-starved MEFs, p110-free-p85s were preferentially, compared with heterodimeric p85s, bound to PDGFRs, consistent with in vitro assays that demonstrated they bound PDGFR-based tyrosine-phosphorylated peptides with higher affinity and co-operativity; suggesting they may act to tune a PI3K activation threshold. p110α-heterodimers were recruited 5-6× more efficiently than p110β-heterodimers to activated PDGFRs in MEFs or to PDGFR-based tyrosine-phosphorylated peptides in MEF-lysates. This suggests that PI3Kα has a higher affinity for relevant tyrosine-phosphorylated motifs than PI3Kβ. Nevertheless, PI3Kβ contributes substantially to acute PDGF-stimulation of PIP3 and PKB in MEFs because it is synergistically, and possibly sequentially, activated by receptor-recruitment and small GTPases (Rac/CDC42) via its RBD, whereas parallel activation of PI3Kα is independent of its RBD. These results begin to provide molecular clarity to the rules of engagement between class IA PI3K subunits in vivo and past work describing "excess p85," p85α as a tumor suppressor, and differential receptor activation of PI3Kα and PI3Kβ.
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Affiliation(s)
- N Tsolakos
- The Signaling Department, The Babraham Institute, CB22 3AT Cambridge, United Kingdom
| | - T N Durrant
- Department of Chemistry, University of Oxford, OX1 3QZ Oxford, United Kingdom
| | - T Chessa
- The Signaling Department, The Babraham Institute, CB22 3AT Cambridge, United Kingdom
| | - S M Suire
- The Signaling Department, The Babraham Institute, CB22 3AT Cambridge, United Kingdom
| | - D Oxley
- The Mass Spec Facility, The Babraham Institute, CB22 3AT Cambridge, United Kingdom
| | - S Kulkarni
- The Signaling Department, The Babraham Institute, CB22 3AT Cambridge, United Kingdom
| | - J Downward
- The Oncogene Biology Lab, The Francis Crick Institute, NW1 1AT London, United Kingdom
| | - O Perisic
- Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, CB2 0QH Cambridge, United Kingdom
| | - R L Williams
- Protein and Nucleic Acid Chemistry, MRC Laboratory of Molecular Biology, CB2 0QH Cambridge, United Kingdom
| | - L Stephens
- The Signaling Department, The Babraham Institute, CB22 3AT Cambridge, United Kingdom;
| | - P T Hawkins
- The Signaling Department, The Babraham Institute, CB22 3AT Cambridge, United Kingdom;
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Sørensen L, Salbo R. Optimized Workflow for Selecting Peptides for HDX-MS Data Analyses. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:2278-2281. [PMID: 30171440 DOI: 10.1007/s13361-018-2056-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 08/09/2018] [Accepted: 08/09/2018] [Indexed: 06/08/2023]
Abstract
Hydrogen deuterium exchange measured by mass spectrometry (HDX-MS) is a commonly used technique for studying the structural dynamics of proteins in solution. The first part of any bottom-up HDX-MS experiment is to identify the peptides generated from a digestion step. This requires manual inspection of the identified peptides to determine their use for HDX-MS analysis, which is a time-consuming task. Throughout the literature, there have been different approaches for removing peptides that do not yield quantifiable HDX information. This includes using validity scores from the software used in the generation of the peptide map and that the peptide should be found in two out of three technical replicate experiments. Here, we analyze the previously available methods for filtering the identified peptides in regard to their ability to predict whether a peptide will provide quantifiable HDX-MS data or not. We also present a new score-based system relying on a combination of MS/MS parameters that offers an improved method for separating quantifiable peptides from the nonquantifiable. Using this score-based method reduces the number of peptide spectra that needs to be manually inspected and thereby the time spent curating HDX-MS data. Graphical Abstract ᅟ.
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Affiliation(s)
- Lars Sørensen
- Global Research Technologies, Novo Nordisk A/S, Novo Nordisk Park, DK-2760, Bagsværd, Denmark.
- Department of Molecular Biology and Genetics, University of Aarhus, Gustav Wieds Vej 10C, DK-8000, Aarhus C, Denmark.
| | - Rune Salbo
- Research and Development, Orion Corporation Orion Pharma, Tengströminkatu 8, FI-20360, Turku, Finland
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Leontiadou H, Galdadas I, Athanasiou C, Cournia Z. Insights into the mechanism of the PIK3CA E545K activating mutation using MD simulations. Sci Rep 2018; 8:15544. [PMID: 30341384 PMCID: PMC6195558 DOI: 10.1038/s41598-018-27044-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 05/04/2018] [Indexed: 12/19/2022] Open
Abstract
Phosphoinositide 3-kinase alpha (PI3Kα) is involved in fundamental cellular processes including cell proliferation and differentiation and is frequently mutated in human malignancies. One of the most common mutations is E545K, which results in an amino acid substitution of opposite charge. It has been recently proposed that in this oncogenic charge-reversal mutation, the interactions between the protein catalytic and regulatory subunits are abrogated, resulting in loss of regulation and constitutive PI3Kα activity, which can lead to oncogenesis. To assess the mechanism of the PI3Kα E545K activating mutation, extensive Molecular Dynamics simulations were performed to examine conformational changes differing between the wild type (WT) and mutant proteins as they occur in microsecond simulations. In the E545K mutant PI3Kα, we observe a spontaneous detachment of the nSH2 PI3Kα domain (regulatory subunit, p85α) from the helical domain (catalytic subunit, p110α) causing significant loss of communication between the regulatory and catalytic subunits. We examine the allosteric network of the two proteins and show that a cluster of residues around the mutation is important for delivering communication signals between the catalytic and regulatory subunits. Our results demonstrate the dynamical and structural effects induced by the p110α E545K mutation in atomic level detail and indicate a possible mechanism for the loss of regulation that E545K confers on PI3Kα.
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Affiliation(s)
- Hari Leontiadou
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527, Athens, Greece
| | - Ioannis Galdadas
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527, Athens, Greece
| | - Christina Athanasiou
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527, Athens, Greece
| | - Zoe Cournia
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527, Athens, Greece.
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34
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Structural Basis for Regulation of Phosphoinositide Kinases and Their Involvement in Human Disease. Mol Cell 2018; 71:653-673. [DOI: 10.1016/j.molcel.2018.08.005] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 06/22/2018] [Accepted: 07/30/2018] [Indexed: 01/09/2023]
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35
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Dornan GL, Burke JE. Molecular Mechanisms of Human Disease Mediated by Oncogenic and Primary Immunodeficiency Mutations in Class IA Phosphoinositide 3-Kinases. Front Immunol 2018; 9:575. [PMID: 29616047 PMCID: PMC5868324 DOI: 10.3389/fimmu.2018.00575] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 03/07/2018] [Indexed: 12/13/2022] Open
Abstract
The signaling lipid phosphatidylinositol 3,4,5, trisphosphate (PIP3) is an essential mediator of many vital cellular processes, including growth, survival, and metabolism. PIP3 is generated through the action of the class I phosphoinositide 3-kinases (PI3K), and their activity is tightly controlled through interactions with regulatory proteins and activating stimuli. The class IA PI3Ks are composed of three distinct p110 catalytic subunits (p110α, p110β, and p110δ), and they play different roles in specific tissues due to disparities in both expression and engagement downstream of cell-surface receptors. Disruption of PI3K regulation is a frequent driver of numerous human diseases. Activating mutations in the PIK3CA gene encoding the p110α catalytic subunit of class IA PI3K are frequently mutated in several cancer types, and mutations in the PIK3CD gene encoding the p110δ catalytic subunit have been identified in primary immunodeficiency patients. All class IA p110 subunits interact with p85 regulatory subunits, and mutations/deletions in different p85 regulatory subunits have been identified in both cancer and primary immunodeficiencies. In this review, we will summarize our current understanding for the molecular basis of how class IA PI3K catalytic activity is regulated by p85 regulatory subunits, and how activating mutations in the PI3K catalytic subunits PIK3CA and PIK3CD (p110α, p110δ) and regulatory subunits PIK3R1 (p85α) mediate PI3K activation and human disease.
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Affiliation(s)
- Gillian L Dornan
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - John E Burke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
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36
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Buckles TC, Ziemba BP, Masson GR, Williams RL, Falke JJ. Single-Molecule Study Reveals How Receptor and Ras Synergistically Activate PI3Kα and PIP 3 Signaling. Biophys J 2017; 113:2396-2405. [PMID: 29211993 PMCID: PMC5738497 DOI: 10.1016/j.bpj.2017.09.018] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 09/15/2017] [Accepted: 09/15/2017] [Indexed: 02/07/2023] Open
Abstract
Cellular pathways controlling chemotaxis, growth, survival, and oncogenesis are activated by receptor tyrosine kinases and small G-proteins of the Ras superfamily that stimulate specific isoforms of phosphatidylinositol-3-kinase (PI3K). These PI3K lipid kinases phosphorylate the constitutive lipid phosphatidylinositol-4,5-bisphosphate (PIP2) to produce the signaling lipid phosphatidylinositol-3,4,5-trisphosphate (PIP3). Progress has been made in understanding direct, moderate PI3K activation by receptors. In contrast, the mechanism by which receptors and Ras synergistically activate PI3K to much higher levels remains unclear, and two competing models have been proposed: membrane recruitment versus activation of the membrane-bound enzyme. To resolve this central mechanistic question, this study employs single-molecule imaging to investigate PI3K activation in a six-component pathway reconstituted on a supported lipid bilayer. The findings reveal that simultaneous activation by a receptor activation loop (from platelet-derived growth factor receptor, a receptor tyrosine kinase) and H-Ras generates strong, synergistic activation of PI3Kα, yielding a large increase in net kinase activity via the membrane recruitment mechanism. Synergy requires receptor phospho-Tyr and two anionic lipids (phosphatidylserine and PIP2) to make PI3Kα competent for bilayer docking, as well as for subsequent binding and phosphorylation of substrate PIP2 to generate product PIP3. Synergy also requires recruitment to membrane-bound H-Ras, which greatly speeds the formation of a stable, membrane-bound PI3Kα complex, modestly slows its off rate, and dramatically increases its equilibrium surface density. Surprisingly, H-Ras binding significantly inhibits the specific kinase activity of the membrane-bound PI3Kα molecule, but this minor enzyme inhibition is overwhelmed by the marked enhancement of membrane recruitment. The findings have direct impacts for the fields of chemotaxis, innate immunity, inflammation, carcinogenesis, and drug design.
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Affiliation(s)
- Thomas C Buckles
- Molecular Biophysics Program and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado
| | - Brian P Ziemba
- Molecular Biophysics Program and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado
| | - Glenn R Masson
- Medical Research Council, Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Roger L Williams
- Medical Research Council, Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Joseph J Falke
- Molecular Biophysics Program and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado.
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37
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Ito Y, Vogt PK, Hart JR. Domain analysis reveals striking functional differences between the regulatory subunits of phosphatidylinositol 3-kinase (PI3K), p85α and p85β. Oncotarget 2017; 8:55863-55876. [PMID: 28915558 PMCID: PMC5593529 DOI: 10.18632/oncotarget.19866] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 07/12/2017] [Indexed: 01/24/2023] Open
Abstract
Our understanding of isoform-specific activities of phosphatidylinositol 3-kinase (PI3K) is still rudimentary, and yet, deep knowledge of these non-redundant functions in the PI3K family is essential for effective and safe control of PI3K in disease. The two major isoforms of the regulatory subunits of PI3K are p85α and p85β, encoded by the genes PIK3R1 and PIK3R2, respectively. These isoforms show distinct functional differences that affect and control cellular PI3K activity and signaling [1–4]. In this study, we have further explored the differences between p85α and p85β by genetic truncations and substitutions. We have discovered unexpected activities of the mutant proteins that reflect regulatory functions of distinct p85 domains. These results can be summarized as follows: Deletion of the SH3 domain increases oncogenic and PI3K signaling activity. Deletion of the combined SH3-RhoGAP domains abolishes these activities. In p85β, deletion of the cSH2 domain reduces oncogenic and signaling activities. In p85α, such a deletion has an activating effect. The deletions of the combined cSH2 and iSH2 domains and also the deletion of the cSH2, iSH2 and nSH2 domains yield results that go in the same direction, generally activating in p85α and reducing activity in p85β. The contrasting functions of the cSH2 domains are verified by domain exchanges with the cSH2 domain of p85β exerting an activating effect and the cSH2 domain of p85α an inactivating effect, even in the heterologous isoform. In the cell systems studied, protein stability was not correlated with oncogenic and signaling activity. These observations significantly expand our knowledge of the isoform-specific activities of p85α and p85β and of the functional significance of specific domains for regulating the catalytic subunits of class IA PI3K.
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Affiliation(s)
- Yoshihiro Ito
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, San Diego, CA, USA
| | - Peter K Vogt
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, San Diego, CA, USA
| | - Jonathan R Hart
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, San Diego, CA, USA
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Regulation of PI3K by PKC and MARCKS: Single-Molecule Analysis of a Reconstituted Signaling Pathway. Biophys J 2017; 110:1811-1825. [PMID: 27119641 DOI: 10.1016/j.bpj.2016.03.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 02/09/2016] [Accepted: 03/07/2016] [Indexed: 12/19/2022] Open
Abstract
In chemotaxing ameboid cells, a complex leading-edge signaling circuit forms on the cytoplasmic leaflet of the plasma membrane and directs both actin and membrane remodeling to propel the leading edge up an attractant gradient. This leading-edge circuit includes a putative amplification module in which Ca(2+)-protein kinase C (Ca(2+)-PKC) is hypothesized to phosphorylate myristoylated alanine-rich C kinase substrate (MARCKS) and release phosphatidylinositol-4,5-bisphosphate (PIP2), thereby stimulating production of the signaling lipid phosphatidylinositol-3,4,5-trisphosphate (PIP3) by the lipid kinase phosphoinositide-3-kinase (PI3K). We investigated this hypothesized Ca(2+)-PKC-MARCKS-PIP2-PI3K-PIP3 amplification module and tested its key predictions using single-molecule fluorescence to measure the surface densities and activities of its protein components. Our findings demonstrate that together Ca(2+)-PKC and the PIP2-binding peptide of MARCKS modulate the level of free PIP2, which serves as both a docking target and substrate lipid for PI3K. In the off state of the amplification module, the MARCKS peptide sequesters PIP2 and thereby inhibits PI3K binding to the membrane. In the on state, Ca(2+)-PKC phosphorylation of the MARCKS peptide reverses the PIP2 sequestration, thereby releasing multiple PIP2 molecules that recruit multiple active PI3K molecules to the membrane surface. These findings 1) show that the Ca(2+)-PKC-MARCKS-PIP2-PI3K-PIP3 system functions as an activation module in vitro, 2) reveal the molecular mechanism of activation, 3) are consistent with available in vivo data, and 4) yield additional predictions that are testable in live cells. More broadly, the Ca(2+)-PKC-stimulated release of free PIP2 may well regulate the membrane association of other PIP2-binding proteins, and the findings illustrate the power of single-molecule analysis to elucidate key dynamic and mechanistic features of multiprotein signaling pathways on membrane surfaces.
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PI3K Signaling in Tissue Hyper-Proliferation: From Overgrowth Syndromes to Kidney Cysts. Cancers (Basel) 2017; 9:cancers9040030. [PMID: 28353628 PMCID: PMC5406705 DOI: 10.3390/cancers9040030] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 03/24/2017] [Accepted: 03/27/2017] [Indexed: 12/19/2022] Open
Abstract
The members of the PhosphoInositide-3 Kinase (PI3K) protein family are well-known regulators of proliferative signals. By the generation of lipid second messengers, they mediate the activation of AKT/PKB (AKT) and mammalian Target Of Rapamycin (mTOR) pathways. Although mutations in the PI3K/AKT/mTOR pathway are highly characterized in cancer, recent evidence indicates that alterations in the proliferative signals are major drivers of other diseases such as overgrowth disorders and polycystic kidney disease. In this review, we briefly summarize the role of the PI3K/AKT/mTOR pathway in cell proliferation by comparing the effect of alterations in PI3K enzymes in different tissues. In particular, we discuss the most recent findings on how the same pathway may lead to different biological effects, due to the convergence and cooperation of different signaling cascades.
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Conformational disruption of PI3Kδ regulation by immunodeficiency mutations in PIK3CD and PIK3R1. Proc Natl Acad Sci U S A 2017; 114:1982-1987. [PMID: 28167755 DOI: 10.1073/pnas.1617244114] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Activated PI3K Delta Syndrome (APDS) is a primary immunodeficiency disease caused by activating mutations in either the leukocyte-restricted p110δ catalytic (PIK3CD) subunit or the ubiquitously expressed p85α regulatory (PIK3R1) subunit of class IA phosphoinositide 3-kinases (PI3Ks). There are two classes of APDS: APDS1 that arises from p110δ mutations that are analogous to oncogenic mutations found in the broadly expressed p110α subunit and APDS2 that occurs from a splice mutation resulting in p85α with a central deletion (Δ434-475). As p85 regulatory subunits associate with and inhibit all class IA catalytic subunits, APDS2 mutations are expected to similarly activate p110α, β, and δ, yet APDS2 largely phenocopies APDS1 without dramatic effects outside the immune system. We have examined the molecular mechanism of activation of both classes of APDS mutations using a combination of biochemical assays and hydrogen-deuterium exchange mass spectrometry. Intriguingly, we find that an APDS2 mutation in p85α leads to substantial basal activation of p110δ (>300-fold) and disrupts inhibitory interactions from the nSH2, iSH2, and cSH2 domains of p85, whereas p110α is only minimally basally activated (∼2-fold) when associated with mutated p85α. APDS1 mutations in p110δ (N334K, E525K, E1021K) mimic the activation mechanisms previously discovered for oncogenic mutations in p110α. All APDS mutations were potently inhibited by the Food and Drug Administration-approved p110δ inhibitor idelalisib. Our results define the molecular basis of how PIK3CD and PIK3R1 mutations result in APDS and reveal a potential path to treatment for all APDS patients.
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Gu G, Chen Y, Duan C, Zhou L, Chen C, Chen J, Cheng J, Shi N, Jin Y, Xi Q, Zhong J. Overexpression of ARF1 is associated with cell proliferation and migration through PI3K signal pathway in ovarian cancer. Oncol Rep 2017; 37:1511-1520. [DOI: 10.3892/or.2017.5388] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 12/15/2016] [Indexed: 11/06/2022] Open
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McPhail JA, Ottosen EH, Jenkins ML, Burke JE. The Molecular Basis of Aichi Virus 3A Protein Activation of Phosphatidylinositol 4 Kinase IIIβ, PI4KB, through ACBD3. Structure 2016; 25:121-131. [PMID: 27989622 DOI: 10.1016/j.str.2016.11.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 10/19/2016] [Accepted: 11/18/2016] [Indexed: 01/12/2023]
Abstract
Phosphatidylinositol 4-kinase III beta (PI4KIIIβ) is an essential enzyme in mediating membrane transport, and plays key roles in facilitating viral infection. Many pathogenic positive-sense single-stranded RNA viruses activate PI4KIIIβ to generate phosphatidylinositol 4-phosphate (PI4P)-enriched organelles for viral replication. The molecular basis for PI4KIIIβ activation during viral infection has remained largely unclear. We describe the biochemical reconstitution and characterization of the complex of PI4KIIIβ with the Golgi protein Acyl-coenzyme A binding domain containing protein 3 (ACBD3) and Aichi virus 3A protein on membranes. We find that 3A directly activates PI4KIIIβ, and this activation is sensitized by ACBD3. The interfaces between PI4KIIIβ-ACBD3 and ACBD3-3A were mapped with hydrogen-deuterium exchange mass spectrometry (HDX-MS). Determination of the crystal structure of the ACBD3 GOLD domain revealed a unique N terminus that mediates the interaction with 3A. Rationally designed complex-disrupting mutations in both ACBD3 and PI4KIIIβ completely abrogated the sensitization of 3A activation by ACBD3.
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Affiliation(s)
- Jacob A McPhail
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8P 5C2, Canada
| | - Erik H Ottosen
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8P 5C2, Canada
| | - Meredith L Jenkins
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8P 5C2, Canada
| | - John E Burke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8P 5C2, Canada.
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Vadas O, Jenkins ML, Dornan GL, Burke JE. Using Hydrogen-Deuterium Exchange Mass Spectrometry to Examine Protein-Membrane Interactions. Methods Enzymol 2016; 583:143-172. [PMID: 28063489 DOI: 10.1016/bs.mie.2016.09.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Many fundamental cellular processes are controlled via assembly of a network of proteins at membrane surfaces. The proper recruitment of proteins to membranes can be controlled by a wide variety of mechanisms, including protein lipidation, protein-protein interactions, posttranslational modifications, and binding to specific lipid species present in membranes. There are, however, only a limited number of analytical techniques that can study the assembly of protein-membrane complexes at the molecular level. A relatively new addition to the set of techniques available to study these protein-membrane systems is the use of hydrogen-deuterium exchange mass spectrometry (HDX-MS). HDX-MS experiments measure protein conformational dynamics in their native state, based on the rate of exchange of amide hydrogens with solvent. This review discusses the use of HDX-MS as a tool to identify the interfaces of proteins with membranes and membrane-associated proteins, as well as define conformational changes elicited by membrane recruitment. Specific examples will focus on the use of HDX-MS to examine how large macromolecular protein complexes are recruited and activated on membranes, and how both posttranslational modifications and cancer-linked oncogenic mutations affect these processes.
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Affiliation(s)
- O Vadas
- Pharmaceutical Sciences Section, University of Geneva, Geneva, Switzerland
| | | | - G L Dornan
- University of Victoria, Victoria BC, Canada
| | - J E Burke
- University of Victoria, Victoria BC, Canada.
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44
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Singh P, Dar MS, Dar MJ. p110α and p110β isoforms of PI3K signaling: are they two sides of the same coin? FEBS Lett 2016; 590:3071-82. [PMID: 27552098 DOI: 10.1002/1873-3468.12377] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 08/20/2016] [Accepted: 08/22/2016] [Indexed: 12/30/2022]
Abstract
Class-1 phosphatidylinositol-3-kinases (PI3Ks) are activated by a variety of extracellular stimuli and have been implicated in a wide range of cellular processes. p110α and p110β are the two most studied isoforms of the class-1A PI3K signaling pathway. Although these two isoforms are ubiquitously expressed and play multiple redundant roles, they also have distinct functions within the cell. More recently, p110α and p110β isoforms have been shown to translocate into the nucleus and play a role in DNA replication and repair, and in cell cycle progression. In the following Review article, we discuss the overlapping and unique roles of p110α and p110β isoforms with a particular focus on their structure, expression analysis, subcellular localization, and signaling contributions in various cell types and model organisms.
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Affiliation(s)
- Paramjeet Singh
- Academy of Scientific and Innovative Research, New Delhi, India.,Cancer Pharmacology Division, CSIR-Indian Institute of Integrative Medicine, Jammu, India
| | - Mohd Saleem Dar
- Academy of Scientific and Innovative Research, New Delhi, India.,Cancer Pharmacology Division, CSIR-Indian Institute of Integrative Medicine, Jammu, India
| | - Mohd Jamal Dar
- Academy of Scientific and Innovative Research, New Delhi, India. .,Cancer Pharmacology Division, CSIR-Indian Institute of Integrative Medicine, Jammu, India.
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45
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Diversity-oriented synthesis yields novel multistage antimalarial inhibitors. Nature 2016; 538:344-349. [PMID: 27602946 DOI: 10.1038/nature19804] [Citation(s) in RCA: 186] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 08/31/2016] [Indexed: 02/08/2023]
Abstract
Antimalarial drugs have thus far been chiefly derived from two sources-natural products and synthetic drug-like compounds. Here we investigate whether antimalarial agents with novel mechanisms of action could be discovered using a diverse collection of synthetic compounds that have three-dimensional features reminiscent of natural products and are underrepresented in typical screening collections. We report the identification of such compounds with both previously reported and undescribed mechanisms of action, including a series of bicyclic azetidines that inhibit a new antimalarial target, phenylalanyl-tRNA synthetase. These molecules are curative in mice at a single, low dose and show activity against all parasite life stages in multiple in vivo efficacy models. Our findings identify bicyclic azetidines with the potential to both cure and prevent transmission of the disease as well as protect at-risk populations with a single oral dose, highlighting the strength of diversity-oriented synthesis in revealing promising therapeutic targets.
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46
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Probing the dynamic regulation of peripheral membrane proteins using hydrogen deuterium exchange-MS (HDX-MS). Biochem Soc Trans 2016; 43:773-86. [PMID: 26517882 DOI: 10.1042/bst20150065] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Many cellular signalling events are controlled by the selective recruitment of protein complexes to membranes. Determining the molecular basis for how lipid signalling complexes are recruited, assembled and regulated on specific membrane compartments has remained challenging due to the difficulty of working in conditions mimicking native biological membrane environments. Enzyme recruitment to membranes is controlled by a variety of regulatory mechanisms, including binding to specific lipid species, protein-protein interactions, membrane curvature, as well as post-translational modifications. A powerful tool to study the regulation of membrane signalling enzymes and complexes is hydrogen deuterium exchange-MS (HDX-MS), a technique that allows for the interrogation of protein dynamics upon membrane binding and recruitment. This review will highlight the theory and development of HDX-MS and its application to examine the molecular basis of lipid signalling enzymes, specifically the regulation and activation of phosphoinositide 3-kinases (PI3Ks).
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47
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Houslay DM, Anderson KE, Chessa T, Kulkarni S, Fritsch R, Downward J, Backer JM, Stephens LR, Hawkins PT. Coincident signals from GPCRs and receptor tyrosine kinases are uniquely transduced by PI3Kβ in myeloid cells. Sci Signal 2016; 9:ra82. [PMID: 27531651 PMCID: PMC5417692 DOI: 10.1126/scisignal.aae0453] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Class I phosphoinositide 3-kinases (PI3Ks) catalyze production of the lipid messenger phosphatidylinositol 3,4,5-trisphosphate (PIP3), which plays a central role in a complex signaling network regulating cell growth, survival, and movement. This network is overactivated in cancer and inflammation, and there is interest in determining the PI3K catalytic subunit (p110α, p110β, p110γ, or p110δ) that should be targeted in different therapeutic contexts. Previous studies have defined unique regulatory inputs for p110β, including direct interaction with Gβγ subunits, Rac, and Rab5. We generated mice with knock-in mutations of p110β that selectively blocked the interaction with Gβγ and investigated its contribution to the PI3K isoform dependency of receptor tyrosine kinase (RTK) and G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptor (GPCR) responses in primary macrophages and neutrophils. We discovered a unique role for p110β in supporting synergistic PIP3 formation in response to the coactivation of macrophages by macrophage colony-stimulating factor (M-CSF) and the complement protein C5a. In contrast, we found partially redundant roles for p110α, p110β, and p110δ downstream of M-CSF alone and a nonredundant role for p110γ downstream of C5a alone. This role for p110β completely depended on direct interaction with Gβγ, suggesting that p110β transduces GPCR signals in the context of coincident activation by an RTK. The p110β-Gβγ interaction was also required for neutrophils to generate reactive oxygen species in response to the Fcγ receptor-dependent recognition of immune complexes and for their β2 integrin-mediated adhesion to fibrinogen or poly-RGD+, directly implicating heterotrimeric G proteins in these two responses.
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Affiliation(s)
- Daniel M Houslay
- Inositide Laboratory, Babraham Institute, Babraham Research Campus, Babraham, Cambridge CB223AT, UK
| | - Karen E Anderson
- Inositide Laboratory, Babraham Institute, Babraham Research Campus, Babraham, Cambridge CB223AT, UK
| | - Tamara Chessa
- Inositide Laboratory, Babraham Institute, Babraham Research Campus, Babraham, Cambridge CB223AT, UK
| | - Suhasini Kulkarni
- Inositide Laboratory, Babraham Institute, Babraham Research Campus, Babraham, Cambridge CB223AT, UK
| | - Ralph Fritsch
- Department of Hematology and Oncology, Freiburg University Medical Centre, Albert-Ludwigs-Universität, Freiburg, Hugstetter Str. 55 79106, Germany
| | - Julian Downward
- Signal Transduction Laboratory, Francis Crick Institute, Lincoln's Inn Fields, London WC2A 3LY, UK
| | - Jonathan M Backer
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Forchheimer 230, Bronx, NY 10461, USA
| | - Len R Stephens
- Inositide Laboratory, Babraham Institute, Babraham Research Campus, Babraham, Cambridge CB223AT, UK.
| | - Phillip T Hawkins
- Inositide Laboratory, Babraham Institute, Babraham Research Campus, Babraham, Cambridge CB223AT, UK.
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48
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Fowler ML, McPhail JA, Jenkins ML, Masson GR, Rutaganira FU, Shokat KM, Williams RL, Burke JE. Using hydrogen deuterium exchange mass spectrometry to engineer optimized constructs for crystallization of protein complexes: Case study of PI4KIIIβ with Rab11. Protein Sci 2016; 25:826-39. [PMID: 26756197 PMCID: PMC4832280 DOI: 10.1002/pro.2879] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Revised: 12/22/2015] [Accepted: 01/07/2016] [Indexed: 01/14/2023]
Abstract
The ability of proteins to bind and interact with protein partners plays fundamental roles in many cellular contexts. X‐ray crystallography has been a powerful approach to understand protein‐protein interactions; however, a challenge in the crystallization of proteins and their complexes is the presence of intrinsically disordered regions. In this article, we describe an application of hydrogen deuterium exchange mass spectrometry (HDX‐MS) to identify dynamic regions within type III phosphatidylinositol 4 kinase beta (PI4KIIIβ) in complex with the GTPase Rab11. This information was then used to design deletions that allowed for the production of diffraction quality crystals. Importantly, we also used HDX‐MS to verify that the new construct was properly folded, consistent with it being catalytically and functionally active. Structures of PI4KIIIβ in an Apo state and bound to the potent inhibitor BQR695 in complex with both GTPγS and GDP loaded Rab11 were determined. This hybrid HDX‐MS/crystallographic strategy revealed novel aspects of the PI4KIIIβ‐Rab11 complex, as well as the molecular mechanism of potency of a PI4K specific inhibitor (BQR695). This approach is widely applicable to protein‐protein complexes, and is an excellent strategy to optimize constructs for high‐resolution structural approaches. PDB Code(s): 5C46; 5C4G
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Affiliation(s)
- Melissa L Fowler
- Department of Biochemistry and Microbiology, University of Victoria, British Columbia, V8P 5C2, Canada
| | - Jacob A McPhail
- Department of Biochemistry and Microbiology, University of Victoria, British Columbia, V8P 5C2, Canada
| | - Meredith L Jenkins
- Department of Biochemistry and Microbiology, University of Victoria, British Columbia, V8P 5C2, Canada
| | - Glenn R Masson
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, United Kingdom
| | - Florentine U Rutaganira
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco (UCSF), California, 94158
| | - Kevan M Shokat
- Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco (UCSF), California, 94158
| | - Roger L Williams
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, United Kingdom
| | - John E Burke
- Department of Biochemistry and Microbiology, University of Victoria, British Columbia, V8P 5C2, Canada
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49
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Cheung LW, Mills GB. Targeting therapeutic liabilities engendered by PIK3R1 mutations for cancer treatment. Pharmacogenomics 2016; 17:297-307. [PMID: 26807692 DOI: 10.2217/pgs.15.174] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The regulatory subunit of PI3K, p85α (encoded by PIK3R1), binds, stabilizes and inhibits the PI3K p110 catalytic subunit. Functional characterization of PIK3R1 mutations has identified not only hypomorphs with reduced inhibition of p110, but also hypomorphs and dominant negative mutants that disrupt a novel regulatory role of p85α on PTEN or neomorphs that activate unexpected signaling pathways. The diverse phenotypic spectrum of these PIK3R1 driver mutations underscores the need for different treatment strategies targeting tumors harboring these mutations. This article describes the functional consequences of the spectrum of PIK3R1 driver mutations and therapeutic liabilities they may engender.
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Affiliation(s)
- Lydia Wt Cheung
- Department of Systems Biology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Gordon B Mills
- Department of Systems Biology, University of Texas MD Anderson Cancer Center, Houston, TX, USA.,Khalifa Bin Zayed Al Nahyan Institute of Personalized Cancer Therapy, University of Texas MD Anderson Cancer Center, Houston, TX, USA
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50
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Chang C, Niu Z, Gu N, Zhao W, Wang G, Jia Y, Li D, Xu C. Analysis of the ways and methods of signaling pathways in regulating cell cycle of NIH3T3 at transcriptional level. BMC Cell Biol 2015; 16:25. [PMID: 26511608 PMCID: PMC4625951 DOI: 10.1186/s12860-015-0071-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 10/19/2015] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND To analyze the ways and methods of signaling pathways in regulating cell cycle progression of NIH3T3 at transcriptional level, we modeled cell cycle of NIH3T3 and found that G1 phase of NIH3T3 cell cycle was at 5-15 h after synchronization, S phase at 15-21 h, G2 phase at 21-22 h, M phase at 22-25 h. RESULTS Mouse Genome 430 2.0 microarray was used to detect the gene expression profiles of the model, and results showed remarkable changes in the expressions of 64 cell cycle genes and 960 genes associated with other physiological activity during the cell cycle of NIH3T3. For the next step, IPA software was used to analyze the physiological activities, cell cycle genes-associated signal transduction activities and their regulatory roles of these genes in cell cycle progression, and our results indicated that the reported genes were involved in 17 signaling pathways in the regulation of cell cycle progression. Newfound genes such as PKC, RAS, PP2A, NGR and PI3K etc. belong to the functional category of molecular mechanism of cancer, cyclins and cell cycle regulation HER-2 signaling in breast cancer signaling pathways. These newfound genes could promote DNA damage repairment and DNA replication progress, regulate the metabolism of protein, and maintain the cell cycle progression of NIH3T3 modulating the reported genes CCND1 and C-FOS. CONCLUSION All of the aforementioned signaling pathways interacted with the cell cycle network, indicating that NIH3T3 cell cycle was regulated by a number of signaling pathways.
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Affiliation(s)
- Cuifang Chang
- College of Life Science, Henan Normal University, No. 46, Construction East Road, Xinxiang, 453007, Henan Province, P. R. China. .,State Key Laboratory Cultivation Base for Cell Differentiation Regulation, Henan Normal University, Xinxiang, 453007, P. R. China.
| | - Zhipeng Niu
- College of Life Science, Henan Normal University, No. 46, Construction East Road, Xinxiang, 453007, Henan Province, P. R. China. .,State Key Laboratory Cultivation Base for Cell Differentiation Regulation, Henan Normal University, Xinxiang, 453007, P. R. China.
| | - Ningning Gu
- College of Life Science, Henan Normal University, No. 46, Construction East Road, Xinxiang, 453007, Henan Province, P. R. China. .,State Key Laboratory Cultivation Base for Cell Differentiation Regulation, Henan Normal University, Xinxiang, 453007, P. R. China.
| | - Weiming Zhao
- College of Life Science, Henan Normal University, No. 46, Construction East Road, Xinxiang, 453007, Henan Province, P. R. China. .,State Key Laboratory Cultivation Base for Cell Differentiation Regulation, Henan Normal University, Xinxiang, 453007, P. R. China.
| | - Gaiping Wang
- College of Life Science, Henan Normal University, No. 46, Construction East Road, Xinxiang, 453007, Henan Province, P. R. China. .,State Key Laboratory Cultivation Base for Cell Differentiation Regulation, Henan Normal University, Xinxiang, 453007, P. R. China.
| | - Yifeng Jia
- College of Life Science, Henan Normal University, No. 46, Construction East Road, Xinxiang, 453007, Henan Province, P. R. China. .,State Key Laboratory Cultivation Base for Cell Differentiation Regulation, Henan Normal University, Xinxiang, 453007, P. R. China.
| | - Deming Li
- College of Life Science, Henan Normal University, No. 46, Construction East Road, Xinxiang, 453007, Henan Province, P. R. China. .,State Key Laboratory Cultivation Base for Cell Differentiation Regulation, Henan Normal University, Xinxiang, 453007, P. R. China.
| | - Cunshuan Xu
- College of Life Science, Henan Normal University, No. 46, Construction East Road, Xinxiang, 453007, Henan Province, P. R. China. .,State Key Laboratory Cultivation Base for Cell Differentiation Regulation, Henan Normal University, Xinxiang, 453007, P. R. China.
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