1
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Luan L, Liang D, Chiu DC, Tei R, Baskin JM. Imaging Interorganelle Phospholipid Transport by Extended Synaptotagmins Using Bioorthogonally Tagged Lipids. ACS Chem Biol 2024; 19:1683-1694. [PMID: 39023576 DOI: 10.1021/acschembio.4c00345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
The proper distribution of lipids within organelle membranes requires rapid interorganelle lipid transport, much of which occurs at membrane contact sites and is mediated by lipid transfer proteins (LTPs). Our current understanding of LTP mechanism and function is based largely on structural studies and in vitro reconstitution. Existing cellular assays for LTP function use indirect readouts, and it remains an open question as to whether substrate specificity and transport kinetics established in vitro are similar in cellular settings. Here, we harness bioorthogonal chemistry to develop tools for direct visualization of interorganelle transport of phospholipids between the plasma membrane (PM) and the endoplasmic reticulum (ER). Unnatural fluorescent phospholipid analogs generated by the transphosphatidylation activity of phospholipase D (PLD) at the PM are rapidly transported to the ER dependent in part upon extended synaptotagmins (E-Syts), a family of LTPs at ER-PM contact sites. Ectopic expression of an artificial E-Syt-based tether at ER-mitochondria contact sites results in fluorescent phospholipid accumulation in mitochondria. Finally, in vitro reconstitution assays demonstrate that the fluorescent lipids are bona fide E-Syt substrates. Thus, fluorescent lipids generated in situ via PLD activity and bioorthogonal chemical tagging can enable direct visualization of the activity of LTPs that mediate bulk phospholipid transport at ER-PM contact sites.
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Affiliation(s)
- Lin Luan
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853, United States
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, United States
| | - Dongjun Liang
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853, United States
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Din-Chi Chiu
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853, United States
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Reika Tei
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853, United States
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Jeremy M Baskin
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853, United States
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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2
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Liu Y, Zhou J, Wang Y, Baskaran D, Wang H. Unnatural lipids for simultaneous mRNA delivery and metabolic cell labeling. Biomater Sci 2024; 12:4170-4180. [PMID: 38976288 PMCID: PMC11303094 DOI: 10.1039/d4bm00625a] [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] [Indexed: 07/09/2024]
Abstract
Lipids have demonstrated tremendous promise for mRNA delivery, as evidenced by the success of Covid-19 mRNA vaccines. However, existing lipids are mostly used as delivery vehicles and lack the ability to monitor and further modulate the target cells. Here, for the first time, we report a class of unnatural lipids (azido-DOTAP) that can efficiently deliver mRNAs into cells and meanwhile metabolically label cells with unique chemical tags (e.g., azido groups). The azido tags expressed on the cell membrane enable the monitoring of transfected cells, and can mediate subsequent conjugation of cargos via efficient click chemistry for further modulation of transfected cells. We further demonstrate that the dual-functional unnatural lipid is applicable to different types of cells including dendritic cells, the prominent type of antigen presenting cells, potentially opening a new avenue to developing enhanced mRNA vaccines.
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Affiliation(s)
- Yusheng Liu
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Jiadiao Zhou
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Yueji Wang
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Dhyanesh Baskaran
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Hua Wang
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
- Cancer Center at Illinois (CCIL), Urbana, IL 61801, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Carle College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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3
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Quirion L, Robert A, Boulais J, Huang S, Bernal Astrain G, Strakhova R, Jo CH, Kherdjemil Y, Faubert D, Thibault MP, Kmita M, Baskin JM, Gingras AC, Smith MJ, Côté JF. Mapping the global interactome of the ARF family reveals spatial organization in cellular signaling pathways. J Cell Sci 2024; 137:jcs262140. [PMID: 38606629 PMCID: PMC11166204 DOI: 10.1242/jcs.262140] [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: 03/23/2024] [Accepted: 04/08/2024] [Indexed: 04/13/2024] Open
Abstract
The ADP-ribosylation factors (ARFs) and ARF-like (ARL) GTPases serve as essential molecular switches governing a wide array of cellular processes. In this study, we used proximity-dependent biotin identification (BioID) to comprehensively map the interactome of 28 out of 29 ARF and ARL proteins in two cellular models. Through this approach, we identified ∼3000 high-confidence proximal interactors, enabling us to assign subcellular localizations to the family members. Notably, we uncovered previously undefined localizations for ARL4D and ARL10. Clustering analyses further exposed the distinctiveness of the interactors identified with these two GTPases. We also reveal that the expression of the understudied member ARL14 is confined to the stomach and intestines. We identified phospholipase D1 (PLD1) and the ESCPE-1 complex, more precisely, SNX1, as proximity interactors. Functional assays demonstrated that ARL14 can activate PLD1 in cellulo and is involved in cargo trafficking via the ESCPE-1 complex. Overall, the BioID data generated in this study provide a valuable resource for dissecting the complexities of ARF and ARL spatial organization and signaling.
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Affiliation(s)
- Laura Quirion
- Montreal Clinical Research Institute (IRCM), Montréal, QC H2W 1R7, Canada
- Molecular Biology Programs, Université de Montréal, Montréal, QC H3T 1J4, Canada
| | - Amélie Robert
- Montreal Clinical Research Institute (IRCM), Montréal, QC H2W 1R7, Canada
| | - Jonathan Boulais
- Montreal Clinical Research Institute (IRCM), Montréal, QC H2W 1R7, Canada
| | - Shiying Huang
- Department of Chemistry and Chemical Biology and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Gabriela Bernal Astrain
- Molecular Biology Programs, Université de Montréal, Montréal, QC H3T 1J4, Canada
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC H3T 1J4, Canada
| | - Regina Strakhova
- Molecular Biology Programs, Université de Montréal, Montréal, QC H3T 1J4, Canada
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC H3T 1J4, Canada
| | - Chang Hwa Jo
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC H3T 1J4, Canada
| | - Yacine Kherdjemil
- Montreal Clinical Research Institute (IRCM), Montréal, QC H2W 1R7, Canada
| | - Denis Faubert
- Montreal Clinical Research Institute (IRCM), Montréal, QC H2W 1R7, Canada
| | | | - Marie Kmita
- Montreal Clinical Research Institute (IRCM), Montréal, QC H2W 1R7, Canada
- Molecular Biology Programs, Université de Montréal, Montréal, QC H3T 1J4, Canada
- Department of Medicine, Université de Montréal, Montréal, QC H3C 3J7, Canada
- Department of Experimental Medicine, McGill University, Montréal, QC H3G 2M1, Canada
| | - Jeremy M. Baskin
- Department of Chemistry and Chemical Biology and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Anne-Claude Gingras
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Matthew J. Smith
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC H3T 1J4, Canada
| | - Jean-François Côté
- Montreal Clinical Research Institute (IRCM), Montréal, QC H2W 1R7, Canada
- Molecular Biology Programs, Université de Montréal, Montréal, QC H3T 1J4, Canada
- Department of Medicine, Université de Montréal, Montréal, QC H3C 3J7, Canada
- Department of Anatomy and Cell Biology, McGill University, Montréal, QC H3A 0C7, Canada
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4
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O’Callaghan P, Idevall-Hagren O. "Blue Light, Camera, Action!". ACS CENTRAL SCIENCE 2024; 10:514-516. [PMID: 38559309 PMCID: PMC10979495 DOI: 10.1021/acscentsci.4c00317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Affiliation(s)
- Paul O’Callaghan
- Department of Medical Cell Biology, Uppsala University, Uppsala 75123, Sweden
| | - Olof Idevall-Hagren
- Department of Medical Cell Biology, Uppsala University, Uppsala 75123, Sweden
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5
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Quirion L, Robert A, Boulais J, Huang S, Bernal Astrain G, Strakhova R, Jo CH, Kherdjemil Y, Thibault MP, Faubert D, Kmita M, Baskin JM, Gingras AC, Smith MJ, Cote JF. Mapping the global interactome of the ARF family reveals spatial organization in cellular signaling pathways. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.03.01.530598. [PMID: 36909472 PMCID: PMC10002736 DOI: 10.1101/2023.03.01.530598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
The ADP-ribosylation factors (ARFs) and ARF-like (ARLs) GTPases serve as essential molecular switches governing a wide array of cellular processes. In this study, we utilized proximity-dependent biotin identification (BioID) to comprehensively map the interactome of 28 out of 29 ARF and ARL proteins in two cellular models. Through this approach, we identified ~3000 high-confidence proximal interactors, enabling us to assign subcellular localizations to the family members. Notably, we uncovered previously undefined localizations for ARL4D and ARL10. Clustering analyses further exposed the distinctiveness of the interactors identified with these two GTPases. We also reveal that the expression of the understudied member ARL14 is confined to the stomach and intestines. We identified phospholipase D1 (PLD1) and the ESCPE-1 complex, more precisely SNX1, as proximity interactors. Functional assays demonstrated that ARL14 can activate PLD1 in cellulo and is involved in cargo trafficking via the ESCPE-1 complex. Overall, the BioID data generated in this study provide a valuable resource for dissecting the complexities of ARF and ARL spatial organization and signaling.
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6
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Waghwala SP, Ngo T, Verkaik A. Imaging Phospholipase D Activity with Clickable Alcohols via Transphosphatidylation. Methods Mol Biol 2024; 2816:129-138. [PMID: 38977594 DOI: 10.1007/978-1-0716-3902-3_12] [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] [Indexed: 07/10/2024]
Abstract
Phospholipase D (PLD) is an enzyme with many functions, one of which is the synthesis of phosphatidic acid (PA), a molecule with a myriad of effects on various organ systems and processes. These numerous roles make it hard to understand the true action of PA in cellular and bodily processes. Imaging PLD activity is one way to better understand the synthesis of PA and start to elucidate its function. However, many of the current imaging techniques for PLD come with limitations. This chapter presents a thorough methodology of a new imaging technique for PLD activity with clickable alcohols via transphosphatidylation (IMPACT) and Real-Time IMPACT (RT-IMPACT) that takes advantage of clickable chemistry to overcome current limitations. Using strain-promoted azide-alkyne cycloaddition (SPAAC), inverse electron-demand Diels-Alder (IEDDA), and the synthesis of various organic compounds, this chapter will explain a step-by-step procedure of how to perform the IMPACT and RT-IMPACT method(s).
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Affiliation(s)
- Shyamal P Waghwala
- Bascom Palmer Eye Institute, Miami Integrative Metabolomics Research Center, University of Miami Miller School of Medicine, Miami, FL, USA.
- The University of Texas at Southwestern Medical School, Dallas, TX, USA.
| | - Taylor Ngo
- Bascom Palmer Eye Institute, Miami Integrative Metabolomics Research Center, University of Miami Miller School of Medicine, Miami, FL, USA
- California Northstate University College of Medicine, Elk Grove, CA, USA
| | - Ainsely Verkaik
- Bascom Palmer Eye Institute, Miami Integrative Metabolomics Research Center, University of Miami Miller School of Medicine, Miami, FL, USA
- College of Optometry, Nova Southeastern University, Fort Lauderdale, FL, USA
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7
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Tei R, Bagde SR, Fromme JC, Baskin JM. Activity-based directed evolution of a membrane editor in mammalian cells. Nat Chem 2023; 15:1030-1039. [PMID: 37217787 PMCID: PMC10525039 DOI: 10.1038/s41557-023-01214-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 04/24/2023] [Indexed: 05/24/2023]
Abstract
Cellular membranes contain numerous lipid species, and efforts to understand the biological functions of individual lipids have been stymied by a lack of approaches for controlled modulation of membrane composition in situ. Here we present a strategy for editing phospholipids, the most abundant lipids in biological membranes. Our membrane editor is based on a bacterial phospholipase D (PLD), which exchanges phospholipid head groups through hydrolysis or transphosphatidylation of phosphatidylcholine with water or exogenous alcohols. Exploiting activity-dependent directed enzyme evolution in mammalian cells, we have developed and structurally characterized a family of 'superPLDs' with up to a 100-fold enhancement in intracellular activity. We demonstrate the utility of superPLDs for both optogenetics-enabled editing of phospholipids within specific organelle membranes in live cells and biocatalytic synthesis of natural and unnatural designer phospholipids in vitro. Beyond the superPLDs, activity-based directed enzyme evolution in mammalian cells is a generalizable approach to engineer additional chemoenzymatic biomolecule editors.
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Affiliation(s)
- Reika Tei
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | - Saket R Bagde
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - J Christopher Fromme
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Jeremy M Baskin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA.
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA.
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8
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Abstract
Lipids are key components of all organisms. We are well educated in their use as fuel and their essential role to form membranes. We also know much about their biosynthesis and metabolism. We are also aware that most lipids have signaling character meaning that a change in their concentration or location constitutes a signal that helps a living cell to respond to changes in the environment or to fulfill its specific function ranging from secretion to cell division. What is much less understood is how lipids change location in cells over time and what other biomolecules they interact with at each stage of their lifetime. Due to the large number of often quite similar lipid species and the sometimes very short lifetime of signaling lipids, we need highly specific tools to manipulate and visualize lipids and lipid-protein interactions. If successfully applied, these tools provide fabulous opportunities for discovery.In this Account, I summarize the development of synthetic tools from our lab that were designed to address crucial properties that allow them to function as tools in live cell experiments. Techniques to change the concentration of lipids by adding a small molecule or by light are described and complemented by examples of biological findings made when applying the tools. This ranges from chemical dimerizer-based systems to synthetic "caged" lipid derivatives. Furthermore, I discuss the problem of locating a lipid in an intact cell. Synthetic molecular probes are described that help to unravel the lipid location and to determine their binding proteins. These location studies require in-cell lipid tagging by click chemistry, photo-cross-linking to prevent further movement and the "caging" groups to avoid premature metabolism. The combination of these many technical features in a single tool allows for the analysis of not only lipid fluxes through metabolism but also lipid transport from one membrane to another as well as revealing the lipid interactome in a cell-dependent manner. This latter point is crucial because with these multifunctional tools in combination with lipidomics we can now address differences in healthy versus diseased cells and ultimately find the changes that are essential for disease development and new therapeutics that prevent these changes.
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Affiliation(s)
- Carsten Schultz
- Department of Chemical Physiology and
Biochemistry, Oregon Health & Science
University, Portland, Oregon 97239, United States
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9
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Shanbhag K, Sharma K, Kamat SS. Photoreactive bioorthogonal lipid probes and their applications in mammalian biology. RSC Chem Biol 2023; 4:37-46. [PMID: 36685253 PMCID: PMC9811504 DOI: 10.1039/d2cb00174h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 11/24/2022] [Indexed: 12/14/2022] Open
Abstract
Lipids are an important class of biological molecules that possess many critical physiological functions, which enable the optimal survival of all organisms, including humans. While the role of lipids in the formation of biological cellular membranes and as a source of energy is fairly well understood, the cellular signalling pathways that lipids modulate in mammals are, in comparison, poorly characterized mechanistically and/or largely unknown. In an effort to dissect these mammalian cellular pathways regulated by signalling lipids and map hitherto unknown protein-lipid interactions, the last two decades have seen tremendous progress in the development of multifunctional lipid probes that, in conjunction with well-established bioorthogonal chemistries and chemoproteomics platforms, has almost exponentially expanded our knowledge in this field. In this review, we focus on the various photoreactive bioorthogonal lipid probes described in the literature, and briefly summarize the different photo-crosslinking groups and bioorthogonal chemistries used by them. Furthermore, we report specific case examples of such photoreactive bioorthogonal lipid probes, and discuss the new biological pathways and insights that have emerged from their use through chemoproteomics in mammalian cells. Finally, we highlight the challenges associated with the use of lipid probes in biological systems, and highlight their importance in the discovery and mechanistic understanding of lipid signalling pathways in the years to come.
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Affiliation(s)
- Karthik Shanbhag
- Department of Biology, Indian Institute of Science Education and Research (IISER), Dr Homi Bhabha Road, Pashan Pune 411008 Maharashtra India
| | - Kavita Sharma
- Department of Biology, Indian Institute of Science Education and Research (IISER), Dr Homi Bhabha Road, Pashan Pune 411008 Maharashtra India
| | - Siddhesh S Kamat
- Department of Biology, Indian Institute of Science Education and Research (IISER), Dr Homi Bhabha Road, Pashan Pune 411008 Maharashtra India
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10
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Tei R, Baskin JM. Click chemistry and optogenetic approaches to visualize and manipulate phosphatidic acid signaling. J Biol Chem 2022; 298:101810. [PMID: 35276134 PMCID: PMC9006657 DOI: 10.1016/j.jbc.2022.101810] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 02/12/2022] [Accepted: 02/19/2022] [Indexed: 12/28/2022] Open
Abstract
The simple structure of phosphatidic acid (PA) belies its complex biological functions as both a key phospholipid biosynthetic intermediate and a potent signaling molecule. In the latter role, PA controls processes including vesicle trafficking, actin dynamics, cell growth, and migration. However, experimental methods to decode the pleiotropy of PA are sorely lacking. Because PA metabolism and trafficking are rapid, approaches to accurately visualize and manipulate its levels require high spatiotemporal precision. Here, we describe recent efforts to create a suite of chemical tools that enable imaging and perturbation of PA signaling. First, we describe techniques to visualize PA production by phospholipase D (PLD) enzymes, which are major producers of PA, called Imaging Phospholipase D Activity with Clickable Alcohols via Transphosphatidylation (IMPACT). IMPACT harnesses the ability of endogenous PLD enzymes to accept bioorthogonally tagged alcohols in transphosphatidylation reactions to generate functionalized reporter lipids that are subsequently fluorescently tagged via click chemistry. Second, we describe two light-controlled approaches for precisely manipulating PA signaling. Optogenetic PLDs use light-mediated heterodimerization to recruit a bacterial PLD to desired organelle membranes, and photoswitchable PA analogs contain azobenzene photoswitches in their acyl tails, enabling molecular shape and bioactivity to be controlled by light. We highlight select applications of these tools for studying GPCR-Gq signaling, discovering regulators of PLD signaling, tracking intracellular lipid transport pathways, and elucidating new oncogenic signaling roles for PA. We envision that these chemical tools hold promise for revealing many new insights into lipid signaling pathways.
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Affiliation(s)
- Reika Tei
- Department of Chemistry and Chemical Biology and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, USA
| | - Jeremy M Baskin
- Department of Chemistry and Chemical Biology and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York, USA.
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11
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Activity-based, bioorthogonal imaging of phospholipase D reveals spatiotemporal dynamics of GPCR-Gq signaling. Cell Chem Biol 2022; 29:67-73.e3. [PMID: 34161786 PMCID: PMC8655016 DOI: 10.1016/j.chembiol.2021.05.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/29/2021] [Accepted: 05/27/2021] [Indexed: 01/22/2023]
Abstract
Canonically, G-protein-coupled receptor (GPCR) signaling is transient and confined to the plasma membrane (PM). Deviating from this paradigm, the parathyroid hormone receptor (PTHR1) stimulates sustained Gs signaling at endosomes. In addition to Gs, PTHR1 activates Gq signaling; yet, in contrast to the PTHR1-Gs pathway, the spatiotemporal dynamics of the Gq branch of PTHR1 signaling and its relationship to Gs signaling remain largely ill defined. Recognizing that a downstream consequence of Gq signaling is the activation of phospholipase D (PLD) enzymes, we leverage activity-based, bioorthogonal imaging tools for PLD signaling to visualize and quantify the Gq branch of PTHR1 signaling. We establish that PTHR1-Gq signaling is short lived, exclusively at the PM, and antagonized by PTHR1 endocytosis. Our data support a model wherein Gq and Gs compete for ligand-bound receptors at the PM and more broadly highlight the utility of bioorthogonal tools for imaging PLDs as probes to visualize GPCR-Gq signaling.
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12
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Click chemistry-enabled CRISPR screening reveals GSK3 as a regulator of PLD signaling. Proc Natl Acad Sci U S A 2021; 118:2025265118. [PMID: 34810254 DOI: 10.1073/pnas.2025265118] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/06/2021] [Indexed: 12/20/2022] Open
Abstract
Enzymes that produce second messengers are highly regulated. Revealing the mechanisms underlying such regulation is critical to understanding both how cells achieve specific signaling outcomes and return to homeostasis following a particular stimulus. Pooled genome-wide CRISPR screens are powerful unbiased approaches to elucidate regulatory networks, their principal limitation being the choice of phenotype selection. Here, we merge advances in bioorthogonal fluorescent labeling and CRISPR screening technologies to discover regulators of phospholipase D (PLD) signaling, which generates the potent lipid second messenger phosphatidic acid. Our results reveal glycogen synthase kinase 3 as a positive regulator of protein kinase C and PLD signaling. More generally, this work demonstrates how bioorthogonal, activity-based fluorescent tagging can expand the power of CRISPR screening to uncover mechanisms regulating specific enzyme-driven signaling pathways in mammalian cells.
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