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Kalogriopoulos NA, Tei R, Yan Y, Ravalin M, Li Y, Ting A. Synthetic G protein-coupled receptors for programmable sensing and control of cell behavior. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.15.589622. [PMID: 38659921 PMCID: PMC11042292 DOI: 10.1101/2024.04.15.589622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Synthetic receptors that mediate antigen-dependent cell responses are transforming therapeutics, drug discovery, and basic research. However, established technologies such as chimeric antigen receptors (CARs) can only detect immobilized antigens, have limited output scope, and lack built-in drug control. Here, we engineer synthetic G protein-coupled receptors (GPCRs) capable of driving a wide range of native or nonnative cellular processes in response to user-defined antigen. We achieve modular antigen gating by engineering and fusing a conditional auto-inhibitory domain onto GPCR scaffolds. Antigen binding to a fused nanobody relieves auto-inhibition and enables receptor activation by drug, thus generating Programmable Antigen-gated G protein-coupled Engineered Receptors (PAGERs). We create PAGERs responsive to more than a dozen biologically and therapeutically important soluble and cell surface antigens, in a single step, from corresponding nanobody binders. Different PAGER scaffolds permit antigen binding to drive transgene expression, real-time fluorescence, or endogenous G protein activation, enabling control of cytosolic Ca 2+ , lipid signaling, cAMP, and neuronal activity. Due to its modular design and generalizability, we expect PAGER to have broad utility in discovery and translational science.
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2
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Zong P, Feng J, Legere N, Li Y, Yue Z, Li CX, Mori Y, Miller B, Hao B, Yue L. TRPM2 enhances ischemic excitotoxicity by associating with PKCγ. Cell Rep 2024; 43:113722. [PMID: 38308841 PMCID: PMC11023021 DOI: 10.1016/j.celrep.2024.113722] [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: 07/17/2023] [Revised: 11/30/2023] [Accepted: 01/13/2024] [Indexed: 02/05/2024] Open
Abstract
N-methyl-D-aspartate receptor (NMDAR)-mediated glutamate excitotoxicity significantly contributes to ischemic neuronal death and post-recanalization infarction expansion. Despite tremendous efforts, targeting NMDARs has proven unsuccessful in clinical trials for mitigating brain injury. Here, we show the discovery of an interaction motif for transient receptor potential melastatin 2 (TRPM2) and protein kinase Cγ (PKCγ) association and demonstrate that TRPM2-PKCγ uncoupling is an effective therapeutic strategy for attenuating NMDAR-mediated excitotoxicity in ischemic stroke. We demonstrate that the TRPM2-PKCγ interaction allows TRPM2-mediated Ca2+ influx to promote PKCγ activation, which subsequently enhances TRPM2-induced potentiation of extrasynaptic NMDAR (esNMDAR) activity. By identifying the PKCγ binding motif on TRPM2 (M2PBM), which directly associates with the C2 domain of PKCγ, an interfering peptide (TAT-M2PBM) is developed to disrupt TRPM2-PKCγ interaction without compromising PKCγ function. M2PBM deletion or TRPM2-PKCγ dissociation abolishes both TRPM2-PKCγ and TRPM2-esNMDAR couplings, resulting in reduced excitotoxic neuronal death and attenuated ischemic brain injury.
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Affiliation(s)
- Pengyu Zong
- Department of Cell Biology, Calhoun Cardiology Center, University of Connecticut School of Medicine (UConn Health), Farmington, CT 06030, USA; Institute for the Brain and Cognitive Sciences, University of Connecticut, 337 Mansfield Road, Unit 1272, Storrs, CT 06269, USA
| | - Jianlin Feng
- Department of Cell Biology, Calhoun Cardiology Center, University of Connecticut School of Medicine (UConn Health), Farmington, CT 06030, USA
| | - Nicholas Legere
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, USA; Department of Genetics and Genome Sciences, UConn Health, Farmington, CT 06030, USA
| | - Yunfeng Li
- Department of Molecular Biology and Biophysics, University of Connecticut School of Medicine (UConn Health), Farmington, CT 06030, USA
| | - Zhichao Yue
- Department of Cell Biology, Calhoun Cardiology Center, University of Connecticut School of Medicine (UConn Health), Farmington, CT 06030, USA
| | - Cindy X Li
- Department of Cell Biology, Calhoun Cardiology Center, University of Connecticut School of Medicine (UConn Health), Farmington, CT 06030, USA; Institute for the Brain and Cognitive Sciences, University of Connecticut, 337 Mansfield Road, Unit 1272, Storrs, CT 06269, USA
| | - Yasuo Mori
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Barbara Miller
- Departments of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, P.O. Box 850, Hershey, PA 17033, USA
| | - Bing Hao
- Department of Molecular Biology and Biophysics, University of Connecticut School of Medicine (UConn Health), Farmington, CT 06030, USA
| | - Lixia Yue
- Department of Cell Biology, Calhoun Cardiology Center, University of Connecticut School of Medicine (UConn Health), Farmington, CT 06030, USA.
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Lander A, Kong Y, Jin Y, Wu C, Luk LYP. Deciphering the Synthetic and Refolding Strategy of a Cysteine-Rich Domain in the Tumor Necrosis Factor Receptor (TNF-R) for Racemic Crystallography Analysis and d-Peptide Ligand Discovery. ACS BIO & MED CHEM AU 2024; 4:68-76. [PMID: 38404743 PMCID: PMC10885103 DOI: 10.1021/acsbiomedchemau.3c00060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 11/14/2023] [Accepted: 11/15/2023] [Indexed: 02/27/2024]
Abstract
Many cell-surface receptors are promising targets for chemical synthesis because of their critical roles in disease development. This synthetic approach enables investigations by racemic protein crystallography and ligand discovery by mirror-image methodologies. However, due to their complex nature, the chemical synthesis of a receptor can be a significant challenge. Here, we describe the chemical synthesis and folding of a central, cysteine-rich domain of the cell-surface receptor tumor necrosis factor 1 which is integral to binding of the cytokine TNF-α, namely, TNFR-1 CRD2. Racemic protein crystallography at 1.4 Å confirmed that the native binding conformation was preserved, and TNFR-1 CRD2 maintained its capacity to bind to TNF-α (KD ≈ 7 nM). Encouraged by this discovery, we carried out mirror-image phage display using the enantiomeric receptor mimic and identified a d-peptide ligand for TNFR-1 CRD2 (KD = 1 μM). This work demonstrated that cysteine-rich domains, including the central domains, can be chemically synthesized and used as mimics for investigations.
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Affiliation(s)
- Alexander
J. Lander
- School
of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K.
| | - Yifu Kong
- Department
of Chemistry, College of Chemistry and Chemical Engineering, The MOE
Key Laboratory of Spectrochemical Analysis and Instrumentation, State
Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Fujian Province 361005, China
| | - Yi Jin
- Manchester
Institute of Biotechnology, University of
Manchester, Manchester M1 7DN, U.K.
| | - Chuanliu Wu
- Department
of Chemistry, College of Chemistry and Chemical Engineering, The MOE
Key Laboratory of Spectrochemical Analysis and Instrumentation, State
Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Fujian Province 361005, China
| | - Louis Y. P. Luk
- School
of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K.
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4
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Hu Y, Zhang RQ, Liu SL, Wang ZG. In-situ quantification of lipids in live cells through imaging approaches. Biosens Bioelectron 2023; 240:115649. [PMID: 37678059 DOI: 10.1016/j.bios.2023.115649] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 08/03/2023] [Accepted: 08/29/2023] [Indexed: 09/09/2023]
Abstract
Lipids are important molecules that are widely distributed within the cell, and they play a crucial role in several biological processes such as cell membrane formation, signaling, cell motility and division. Monitoring the spatiotemporal dynamics of cellular lipids in real-time and quantifying their concentrations in situ is crucial since the local concentration of lipids initiates various signaling pathways that regulate cellular processes. In this review, we first introduced the historical background of lipid quantification methods. We then delve into the current state of the art of in situ lipid quantification, including the establishment and utility of fluorescence imaging techniques based on sensors of lipid-binding domains labeled with organic dyes or fluorescent proteins, and Raman and magnetic resonance imaging (MRI) techniques that do not require lipid labeling. Next, we highlighted the biological applications of live-cell lipid quantification techniques in the study of in situ lipid distribution, lipid transformation, and lipid-mediated signaling pathways. Finally, we discussed the technical challenges and prospects for the development of lipid quantification in live cells, with the aim of promoting the development of in situ lipid quantification in live cells, which may have a profound impact on the biological and medical fields.
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Affiliation(s)
- Yusi Hu
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Centre for New Organic Matter, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Centre for Analytical Sciences, College of Chemistry and School of Medicine, Nankai University, Tianjin, 300071, China
| | - Rui-Qiao Zhang
- Qingdao Academy of Agricultural Sciences, Qingdao, 266100, China
| | - Shu-Lin Liu
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Centre for New Organic Matter, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Centre for Analytical Sciences, College of Chemistry and School of Medicine, Nankai University, Tianjin, 300071, China.
| | - Zhi-Gang Wang
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Centre for New Organic Matter, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Centre for Analytical Sciences, College of Chemistry and School of Medicine, Nankai University, Tianjin, 300071, China.
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5
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Daly C, Plouffe B. Gα q signalling from endosomes: A new conundrum. Br J Pharmacol 2023. [PMID: 37740273 DOI: 10.1111/bph.16248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 08/08/2023] [Accepted: 09/13/2023] [Indexed: 09/24/2023] Open
Abstract
G-protein-coupled receptors (GPCRs) constitute the largest family of membrane receptors, and are involved in the transmission of a variety of extracellular stimuli such as hormones, neurotransmitters, light and odorants into intracellular responses. They regulate every aspect of physiology and, for this reason, about one third of all marketed drugs target these receptors. Classically, upon binding to their agonist, GPCRs are thought to activate G-proteins from the plasma membrane and to stop signalling by subsequent desensitisation and endocytosis. However, accumulating evidence indicates that, upon internalisation, some GPCRs can continue to activate G-proteins in endosomes. Importantly, this signalling from endomembranes mediates alternative cellular responses other than signalling at the plasma membrane. Endosomal G-protein signalling and its physiological relevance have been abundantly documented for Gαs - and Gαi -coupled receptors. Recently, some Gαq -coupled receptors have been reported to activate Gαq on endosomes and mediate important cellular processes. However, several questions relative to the series of cellular events required to translate endosomal Gαq activation into cellular responses remain unanswered and constitute a new conundrum. How are these responses in endosomes mediated in the quasi absence of the substrate for the canonical Gαq -activated effector? Is there another effector? Is there another substrate? If so, how does this alternative endosomal effector or substrate produce a downstream signal? This review aims to unravel and discuss these important questions, and proposes possible routes of investigation.
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Affiliation(s)
- Carole Daly
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, UK
| | - Bianca Plouffe
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, UK
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Leonard TA, Loose M, Martens S. The membrane surface as a platform that organizes cellular and biochemical processes. Dev Cell 2023; 58:1315-1332. [PMID: 37419118 DOI: 10.1016/j.devcel.2023.06.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/22/2023] [Accepted: 06/08/2023] [Indexed: 07/09/2023]
Abstract
Membranes are essential for life. They act as semi-permeable boundaries that define cells and organelles. In addition, their surfaces actively participate in biochemical reaction networks, where they confine proteins, align reaction partners, and directly control enzymatic activities. Membrane-localized reactions shape cellular membranes, define the identity of organelles, compartmentalize biochemical processes, and can even be the source of signaling gradients that originate at the plasma membrane and reach into the cytoplasm and nucleus. The membrane surface is, therefore, an essential platform upon which myriad cellular processes are scaffolded. In this review, we summarize our current understanding of the biophysics and biochemistry of membrane-localized reactions with particular focus on insights derived from reconstituted and cellular systems. We discuss how the interplay of cellular factors results in their self-organization, condensation, assembly, and activity, and the emergent properties derived from them.
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Affiliation(s)
- Thomas A Leonard
- Max Perutz Labs, Vienna Biocenter Campus (VBC), Dr. Bohr-Gasse 9, 1030, Vienna, Austria; Medical University of Vienna, Center for Medical Biochemistry, Dr. Bohr-Gasse 9, 1030, Vienna, Austria.
| | - Martin Loose
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria.
| | - Sascha Martens
- Max Perutz Labs, Vienna Biocenter Campus (VBC), Dr. Bohr-Gasse 9, 1030, Vienna, Austria; University of Vienna, Center for Molecular Biology, Department of Biochemistry and Cell Biology, Dr. Bohr-Gasse 9, 1030, Vienna, Austria.
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7
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Zhang Y, Wang C, Zhang W, Li X. Bioactive peptides for anticancer therapies. BIOMATERIALS TRANSLATIONAL 2023; 4:5-17. [PMID: 37206303 PMCID: PMC10189813 DOI: 10.12336/biomatertransl.2023.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 02/02/2023] [Accepted: 03/10/2023] [Indexed: 05/21/2023]
Abstract
Cancer is a serious concern in public health worldwide. Numerous modalities including surgery, radiotherapy, and chemotherapy, have been used for cancer therapies in clinic. Despite progress in anticancer therapies, the usage of these methods for cancer treatment is often related to deleterious side effects and multidrug resistance of conventional anticancer drugs, which have prompted the development of novel therapeutic methods. Anticancer peptides (ACPs), derived from naturally occurring and modified peptides, have received great attention in these years and emerge as novel therapeutic and diagnostic candidates for cancer therapies, because of several advantages over the current treatment modalities. In this review, the classification and properties of ACPs, the mode of action and mechanism of membrane disruption, as well as the natural sources of bioactive peptides with anticancer activities were summarised. Because of their high efficacy for inducing cancer cell death, certain ACPs have been developed to work as drugs and vaccines, evaluated in varied phases of clinical trials. We expect that this summary could facilitate the understanding and design of ACPs with increased specificity and toxicity towards malignant cells and with reduced side effects to normal cells.
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8
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Spencer-Smith R, Terrell EM, Insinna C, Agamasu C, Wagner ME, Ritt DA, Stauffer J, Stephen AG, Morrison DK. RASopathy mutations provide functional insight into the BRAF cysteine-rich domain and reveal the importance of autoinhibition in BRAF regulation. Mol Cell 2022; 82:4262-4276.e5. [PMID: 36347258 PMCID: PMC9677513 DOI: 10.1016/j.molcel.2022.10.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 07/16/2022] [Accepted: 10/14/2022] [Indexed: 11/09/2022]
Abstract
BRAF is frequently mutated in human cancer and the RASopathy syndromes, with RASopathy mutations often observed in the cysteine-rich domain (CRD). Although the CRD participates in phosphatidylserine (PS) binding, the RAS-RAF interaction, and RAF autoinhibition, the impact of these activities on RAF function in normal and disease states is not well characterized. Here, we analyze a panel of CRD mutations and show that they increase BRAF activity by relieving autoinhibition and/or enhancing PS binding, with relief of autoinhibition being the major factor determining mutation severity. Further, we show that CRD-mediated autoinhibition prevents the constitutive plasma membrane localization of BRAF that causes increased RAS-dependent and RAS-independent function. Comparison of the BRAF- and CRAF-CRDs also indicates that the BRAF-CRD is a stronger mediator of autoinhibition and PS binding, and given the increased catalytic activity of BRAF, our studies reveal a more critical role for CRD-mediated autoinhibition in BRAF regulation.
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Affiliation(s)
- Russell Spencer-Smith
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702 USA
| | - Elizabeth M Terrell
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702 USA
| | - Christine Insinna
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702 USA
| | - Constance Agamasu
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702 USA
| | - Morgan E Wagner
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702 USA
| | - Daniel A Ritt
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702 USA
| | - Jim Stauffer
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702 USA
| | - Andrew G Stephen
- National Cancer Institute RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702 USA
| | - Deborah K Morrison
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702 USA.
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9
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Expression of the GFP-mammalian pleckstrin homology (PH) domain of the phospholipase C δ1 in Saccharomyces cerevisiae BY4741. Mol Biol Rep 2022; 49:4123-4128. [DOI: 10.1007/s11033-022-07414-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 11/25/2022]
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10
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Kanai SM, Heffner C, Cox TC, Cunningham ML, Perez FA, Bauer AM, Reigan P, Carter C, Murray SA, Clouthier DE. Auriculocondylar syndrome 2 results from the dominant-negative action of PLCB4 variants. Dis Model Mech 2022; 15:dmm049320. [PMID: 35284927 PMCID: PMC9066496 DOI: 10.1242/dmm.049320] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 02/22/2022] [Indexed: 12/16/2022] Open
Abstract
Auriculocondylar syndrome 2 (ARCND2) is a rare autosomal dominant craniofacial malformation syndrome linked to multiple genetic variants in the coding sequence of phospholipase C β4 (PLCB4). PLCB4 is a direct signaling effector of the endothelin receptor type A (EDNRA)-Gq/11 pathway, which establishes the identity of neural crest cells (NCCs) that form lower jaw and middle ear structures. However, the functional consequences of PLCB4 variants on EDNRA signaling is not known. Here, we show, using multiple signaling reporter assays, that known PLCB4 variants resulting from missense mutations exert a dominant-negative interference over EDNRA signaling. In addition, using CRISPR/Cas9, we find that F0 mouse embryos modeling one PLCB4 variant have facial defects recapitulating those observed in hypomorphic Ednra mouse models, including a bone that we identify as an atavistic change in the posterior palate/oral cavity. Remarkably, we have identified a similar osseous phenotype in a child with ARCND2. Our results identify the disease mechanism of ARCND2, demonstrate that the PLCB4 variants cause craniofacial differences and illustrate how minor changes in signaling within NCCs may have driven evolutionary changes in jaw structure and function. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Stanley M. Kanai
- Department of Craniofacial Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | | | - Timothy C. Cox
- Departments of Oral and Craniofacial Sciences and Pediatrics, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - Michael L. Cunningham
- University of Washington, Department of Pediatrics, Division of Craniofacial Medicine and Seattle Children's Craniofacial Center, Seattle, WA 98105, USA
| | - Francisco A. Perez
- University of Washington, Department of Radiology and Seattle Children's Hospital, Seattle, WA 98105, USA
| | - Aaron M. Bauer
- Department of Biology, Villanova University, Villanova, PA 19085, USA
| | - Philip Reigan
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Cristan Carter
- Department of Craniofacial Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | | | - David E. Clouthier
- Department of Craniofacial Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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11
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Sensing plasma membrane pore formation induces chemokine production in survivors of regulated necrosis. Dev Cell 2022; 57:228-245.e6. [PMID: 35016014 PMCID: PMC8792343 DOI: 10.1016/j.devcel.2021.12.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 10/04/2021] [Accepted: 12/14/2021] [Indexed: 01/26/2023]
Abstract
Although overwhelming plasma membrane integrity loss leads to cell lysis and necrosis, cells can tolerate a limited level of plasma membrane damage, undergo ESCRT-III-mediated repair, and survive. Here, we find that cells which undergo limited plasma membrane damage from the pore-forming actions of MLKL, GSDMD, perforin, or detergents experience local activation of PKCs through Ca2+ influx at the damage sites. S660-phosphorylated PKCs subsequently activate the TAK1/IKKs axis and RelA/Cux1 complex to trigger chemokine expressions. We observe that in late-stage cancers, cells with active MLKL show expression of CXCL8. Similar expression induction is also found in ischemia-injured kidneys. Chemokines generated in this manner are also indispensable for recruiting immune cells to the dead and dying cells. This plasma membrane integrity-sensing pathway is similar to the well-established yeast cell wall integrity signaling pathway at molecular level, and this suggests an evolutionary conserved mechanism to respond to the cellular barrier damage.
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12
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Moriel-Carretero M. The Many Faces of Lipids in Genome Stability (and How to Unmask Them). Int J Mol Sci 2021; 22:12930. [PMID: 34884734 PMCID: PMC8657548 DOI: 10.3390/ijms222312930] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/12/2021] [Accepted: 11/26/2021] [Indexed: 12/15/2022] Open
Abstract
Deep efforts have been devoted to studying the fundamental mechanisms ruling genome integrity preservation. A strong focus relies on our comprehension of nucleic acid and protein interactions. Comparatively, our exploration of whether lipids contribute to genome homeostasis and, if they do, how, is severely underdeveloped. This disequilibrium may be understood in historical terms, but also relates to the difficulty of applying classical lipid-related techniques to a territory such as a nucleus. The limited research in this domain translates into scarce and rarely gathered information, which with time further discourages new initiatives. In this review, the ways lipids have been demonstrated to, or very likely do, impact nuclear transactions, in general, and genome homeostasis, in particular, are explored. Moreover, a succinct yet exhaustive battery of available techniques is proposed to tackle the study of this topic while keeping in mind the feasibility and habits of "nucleus-centered" researchers.
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Affiliation(s)
- María Moriel-Carretero
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, Centre National de la Recherche Scientifique, CEDEX 5, 34293 Montpellier, France
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13
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Kardani K, Bolhassani A. Antimicrobial/anticancer peptides: bioactive molecules and therapeutic agents. Immunotherapy 2021; 13:669-684. [PMID: 33878901 DOI: 10.2217/imt-2020-0312] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Antimicrobial peptides (AMPs) have been known as host-defense peptides. These cationic and amphipathic peptides are relatively short (∼5-50 L-amino acids) with molecular weight less than 10 kDa. AMPs have various roles including immunomodulatory, angiogenic and antitumor activities. Anticancer peptides (ACPs) are a main subset of AMPs as a novel therapeutic approach against tumor cells. The physicochemical properties of the ACPs influence their cell penetration, stability and efficiency of targeting. Up to now, several databases and web servers for in silico prediction of AMPs/ACPs have been established prior to the lab analysis. The present review focuses on the recent advancement about AMPs/ACPs activities including their in silico prediction by computational tools and their potential applications as therapeutic agents especially in cancer.
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Affiliation(s)
- Kimia Kardani
- Department of Hepatitis & AIDS, Pasteur Institute of Iran, Tehran, Iran.,Iranian Comprehensive Hemophilia Care Center, Tehran, Iran
| | - Azam Bolhassani
- Department of Hepatitis & AIDS, Pasteur Institute of Iran, Tehran, Iran
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14
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Morgenstern TJ, Colecraft HM. Controlling ion channel trafficking by targeted ubiquitination and deubiquitination. Methods Enzymol 2021; 654:139-167. [PMID: 34120711 DOI: 10.1016/bs.mie.2021.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Plasma membrane-localized ion channels are essential for diverse physiological processes such as neurotransmission, muscle contraction, and osmotic homeostasis. The surface density of such ion channels is a major determinant of their function, and tuning this variable is a powerful way to regulate physiology. Dysregulation of ion channel surface density due to inherited or de novo mutations underlies many serious diseases, and molecules that can correct trafficking deficits are potential therapeutics and useful research tools. We have developed targeted ubiquitination and deubiquitination approaches that enable selective posttranslational down- or up-regulation, respectively, of desired ion channels. The method employs bivalent molecules comprised of an ion-channel-targeted nanobody fused to catalytic domains of either an E3 ubiquitin ligase or a deubiquitinase. Here, we use two examples to provide detailed protocols that illustrate the utility of the approach-rescued surface expression of a trafficking-deficient mutant KV7.1 (KCNQ1) channel that causes long QT syndrome, and selective elimination of the CaV2.2 voltage-gated calcium channel from the plasma membrane using targeted ubiquitination. Important aspects of the approach include having a robust assay to measure ion channel surface density and generating nanobody binders to cytosolic domains or subunits of targeted ion channels. Accordingly, we also review available methods for determining ion channel surface density and nanobody selection.
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Affiliation(s)
- Travis J Morgenstern
- Department of Molecular Pharmacology and Therapeutics, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, United States
| | - Henry M Colecraft
- Department of Molecular Pharmacology and Therapeutics, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, United States; Department of Physiology and Cellular Biophysics, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, United States.
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Abstract
Ion channel are embedded in the lipid bilayers of biological membranes. Membrane phospholipids constitute a barrier to ion movement, and they have been considered for a long time as a passive environment for channel proteins. Membrane phospholipids, however, do not only serve as a passive amphipathic environment, but they also modulate channel activity by direct specific lipid-protein interactions. Phosphoinositides are quantitatively minor components of biological membranes, and they play roles in many cellular functions, including membrane traffic, cellular signaling and cytoskeletal organization. Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] is mainly found in the inner leaflet of the plasma membrane. Its role as a potential ion channel regulator was first appreciated over two decades ago and by now this lipid is a well-established cofactor or regulator of many different ion channels. The past two decades witnessed the steady development of techniques to study ion channel regulation by phosphoinositides with progress culminating in recent cryoEM structures that allowed visualization of how PI(4,5)P2 opens some ion channels. This chapter will provide an overview of the methods to study regulation by phosphoinositides, focusing on plasma membrane ion channels and PI(4,5)P2.
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16
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A metabolic reaction-diffusion model for PKCα translocation via PIP2 hydrolysis in an endothelial cell. Biochem J 2020; 477:4071-4084. [PMID: 33026061 DOI: 10.1042/bcj20200484] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 09/08/2020] [Accepted: 10/06/2020] [Indexed: 11/17/2022]
Abstract
Hydrolysis of the phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2) at the cell membrane induces the release of inositol 1,4,5-trisphosphate (IP3) into the cytoplasm and diffusion of diacylglycerol (DAG) through the membrane, respectively. Release of IP3 subsequently increases Ca2+ levels in the cytoplasm, which results in activation of protein kinase C α (PKCα) by Ca2+ and DAG, and finally the translocation of PKCα from the cytoplasm to the membrane. In this study, we developed a metabolic reaction-diffusion framework to simulate PKCα translocation via PIP2 hydrolysis in an endothelial cell. A three-dimensional cell model, divided into membrane and cytoplasm domains, was reconstructed from confocal microscopy images. The associated metabolic reactions were divided into their corresponding domain; PIP2 hydrolysis at the membrane domain resulted in DAG diffusion at the membrane domain and IP3 release into the cytoplasm domain. In the cytoplasm domain, Ca2+ was released from the endoplasmic reticulum, and IP3, Ca2+, and PKCα diffused through the cytoplasm. PKCα bound Ca2+ at, and diffused through, the cytoplasm, and was finally activated by binding with DAG at the membrane. Using our model, we analyzed IP3 and DAG dynamics, Ca2+ waves, and PKCα translocation in response to a microscopic stimulus. We found a qualitative agreement between our simulation results and our experimental results obtained by live-cell imaging. Interestingly, our results suggest that PKCα translocation is dominated by DAG dynamics. This three-dimensional reaction-diffusion mathematical framework could be used to investigate the link between PKCα activation in a cell and cell function.
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17
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Capaci V, Bascetta L, Fantuz M, Beznoussenko GV, Sommaggio R, Cancila V, Bisso A, Campaner E, Mironov AA, Wiśniewski JR, Ulloa Severino L, Scaini D, Bossi F, Lees J, Alon N, Brunga L, Malkin D, Piazza S, Collavin L, Rosato A, Bicciato S, Tripodo C, Mantovani F, Del Sal G. Mutant p53 induces Golgi tubulo-vesiculation driving a prometastatic secretome. Nat Commun 2020; 11:3945. [PMID: 32770028 PMCID: PMC7414119 DOI: 10.1038/s41467-020-17596-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Accepted: 07/03/2020] [Indexed: 12/16/2022] Open
Abstract
TP53 missense mutations leading to the expression of mutant p53 oncoproteins are frequent driver events during tumorigenesis. p53 mutants promote tumor growth, metastasis and chemoresistance by affecting fundamental cellular pathways and functions. Here, we demonstrate that p53 mutants modify structure and function of the Golgi apparatus, culminating in the increased release of a pro-malignant secretome by tumor cells and primary fibroblasts from patients with Li-Fraumeni cancer predisposition syndrome. Mechanistically, interacting with the hypoxia responsive factor HIF1α, mutant p53 induces the expression of miR-30d, which in turn causes tubulo-vesiculation of the Golgi apparatus, leading to enhanced vesicular trafficking and secretion. The mut-p53/HIF1α/miR-30d axis potentiates the release of soluble factors and the deposition and remodeling of the ECM, affecting mechano-signaling and stromal cells activation within the tumor microenvironment, thereby enhancing tumor growth and metastatic colonization.
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Affiliation(s)
- Valeria Capaci
- Laboratorio Nazionale CIB (LNCIB), 34149, Trieste, Italy
| | - Lorenzo Bascetta
- Laboratorio Nazionale CIB (LNCIB), 34149, Trieste, Italy
- International School for Advanced Studies (SISSA), 34146, Trieste, Italy
| | - Marco Fantuz
- Laboratorio Nazionale CIB (LNCIB), 34149, Trieste, Italy
- International School for Advanced Studies (SISSA), 34146, Trieste, Italy
| | | | | | - Valeria Cancila
- Tumor Immunology Unit, Department of Health Science, Human Pathology Section, University of Palermo, School of Medicine, 90133, Palermo, Italy
| | - Andrea Bisso
- Laboratorio Nazionale CIB (LNCIB), 34149, Trieste, Italy
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, 20141, Milan, Italy
| | - Elena Campaner
- Laboratorio Nazionale CIB (LNCIB), 34149, Trieste, Italy
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, 34127, Trieste, Italy
| | - Alexander A Mironov
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), 20139, Milan, Italy
| | - Jacek R Wiśniewski
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 85152, Martinsried, Germany
| | - Luisa Ulloa Severino
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, 34127, Trieste, Italy
| | - Denis Scaini
- International School for Advanced Studies (SISSA), 34146, Trieste, Italy
| | - Fleur Bossi
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, 34127, Trieste, Italy
| | - Jodi Lees
- Genetics and Genome Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
| | - Noa Alon
- Genetics and Genome Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
| | - Ledia Brunga
- Genetics and Genome Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
| | - David Malkin
- Genetics and Genome Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
- Department of Pediatrics, University of Toronto, Toronto, ON, Canada
| | - Silvano Piazza
- Laboratorio Nazionale CIB (LNCIB), 34149, Trieste, Italy
| | - Licio Collavin
- Laboratorio Nazionale CIB (LNCIB), 34149, Trieste, Italy
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, 34127, Trieste, Italy
| | - Antonio Rosato
- Veneto Institute of Oncology IOV-IRCCS, 35128, Padua, Italy
- Department of Surgery, Oncology and Gastroenterology, University of Padova, 35128, Padova, Italy
| | - Silvio Bicciato
- Center for Genome Research, University of Modena and Reggio Emilia, 41125, Modena, Italy
| | - Claudio Tripodo
- Tumor Immunology Unit, Department of Health Science, Human Pathology Section, University of Palermo, School of Medicine, 90133, Palermo, Italy
| | - Fiamma Mantovani
- Laboratorio Nazionale CIB (LNCIB), 34149, Trieste, Italy
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, 34127, Trieste, Italy
| | - Giannino Del Sal
- Laboratorio Nazionale CIB (LNCIB), 34149, Trieste, Italy.
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), 20139, Milan, Italy.
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, 34127, Trieste, Italy.
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18
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Chiangjong W, Chutipongtanate S, Hongeng S. Anticancer peptide: Physicochemical property, functional aspect and trend in clinical application (Review). Int J Oncol 2020; 57:678-696. [PMID: 32705178 PMCID: PMC7384845 DOI: 10.3892/ijo.2020.5099] [Citation(s) in RCA: 168] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 06/26/2020] [Indexed: 01/10/2023] Open
Abstract
Cancer is currently ineffectively treated using therapeutic drugs, and is also able to resist drug action, resulting in increased side effects following drug treatment. A novel therapeutic strategy against cancer cells is the use of anticancer peptides (ACPs). The physicochemical properties, amino acid composition and the addition of chemical groups on the ACP sequence influences their conformation, net charge and orientation of the secondary structure, leading to an effect on targeting specificity and ACP-cell interaction, as well as peptide penetrating capability, stability and efficacy. ACPs have been developed from both naturally occurring and modified peptides by substituting neutral or anionic amino acid residues with cationic amino acid residues, or by adding a chemical group. The modified peptides lead to an increase in the effectiveness of cancer therapy. Due to this effectiveness, ACPs have recently been improved to form drugs and vaccines, which have sequentially been evaluated in various phases of clinical trials. The development of the ACPs remains focused on generating newly modified ACPs for clinical application in order to decrease the incidence of new cancer cases and decrease the mortality rate. The present review could further facilitate the design of ACPs and increase efficacious ACP therapy in the near future.
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Affiliation(s)
- Wararat Chiangjong
- Pediatric Translational Research Unit, Department of Pediatrics, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand
| | - Somchai Chutipongtanate
- Pediatric Translational Research Unit, Department of Pediatrics, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand
| | - Suradej Hongeng
- Division of Hematology and Oncology, Department of Pediatrics, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand
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19
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Bisaria A, Hayer A, Garbett D, Cohen D, Meyer T. Membrane-proximal F-actin restricts local membrane protrusions and directs cell migration. Science 2020; 368:1205-1210. [PMID: 32527825 DOI: 10.1126/science.aay7794] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 02/24/2020] [Accepted: 04/09/2020] [Indexed: 12/14/2022]
Abstract
Cell migration is driven by local membrane protrusion through directed polymerization of F-actin at the front. However, F-actin next to the plasma membrane also tethers the membrane and thus resists outgoing protrusions. Here, we developed a fluorescent reporter to monitor changes in the density of membrane-proximal F-actin (MPA) during membrane protrusion and cell migration. Unlike the total F-actin concentration, which was high in the front of migrating cells, MPA density was low in the front and high in the back. Back-to-front MPA density gradients were controlled by higher cofilin-mediated turnover of F-actin in the front. Furthermore, nascent membrane protrusions selectively extended outward from areas where MPA density was reduced. Thus, locally low MPA density directs local membrane protrusions and stabilizes cell polarization during cell migration.
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Affiliation(s)
- Anjali Bisaria
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA.
| | - Arnold Hayer
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Damien Garbett
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Daniel Cohen
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Tobias Meyer
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065, USA
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20
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Miller RC, Aplin CP, Kay TM, Leighton R, Libal C, Simonet R, Cembran A, Heikal AA, Boersma AJ, Sheets ED. FRET Analysis of Ionic Strength Sensors in the Hofmeister Series of Salt Solutions Using Fluorescence Lifetime Measurements. J Phys Chem B 2020; 124:3447-3458. [PMID: 32267692 DOI: 10.1021/acs.jpcb.9b10498] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Living cells are complex, crowded, and dynamic and continually respond to environmental and intracellular stimuli. They also have heterogeneous ionic strength with compartmentalized variations in both intracellular concentrations and types of ions. These challenges would benefit from the development of quantitative, noninvasive approaches for mapping the heterogeneous ionic strength fluctuations in living cells. Here, we investigated a class of recently developed ionic strength sensors that consists of mCerulean3 (a cyan fluorescent protein) and mCitrine (a yellow fluorescent protein) tethered via a linker made of two charged α-helices and a flexible loop. The two helices are designed to bear opposite charges, which is hypothesized to increase the ionic screening and therefore a larger intermolecular distance. In these protein constructs, mCerulean3 and mCitrine act as a donor-acceptor pair undergoing Förster resonance energy transfer (FRET) that is dependent on both the linker amino acids and the environmental ionic strength. Using time-resolved fluorescence of the donor (mCerulean3), we determined the sensitivity of the energy transfer efficiencies and the donor-acceptor distances of these sensors at variable concentrations of the Hofmeister series of salts (KCl, LiCl, NaCl, NaBr, NaI, Na2SO4). As controls, similar measurements were carried out on the FRET-incapable, enzymatically cleaved counterparts of these sensors as well as a construct designed with two electrostatically neutral α-helices (E6G2). Our results show that the energy transfer efficiencies of these sensors are sensitive to both the linker amino acid sequence and the environmental ionic strength, whereas the sensitivity of these sensors to the identity of the dissolved ions of the Hofmeister series of salts seems limited. We also developed a theoretical framework to explain the observed trends as a function of the ionic strength in terms of the Debye screening of the electrostatic interaction between the two charged α-helices in the linker region. These controlled solution studies represent an important step toward the development of rationally designed FRET-based environmental sensors while offering different models for calculating the energy transfer efficiency using time-resolved fluorescence that is compatible with future in vivo studies.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Arnold J Boersma
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52056 Aachen, Germany
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21
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Live-cell lipid biochemistry reveals a role of diacylglycerol side-chain composition for cellular lipid dynamics and protein affinities. Proc Natl Acad Sci U S A 2020; 117:7729-7738. [PMID: 32213584 PMCID: PMC7149225 DOI: 10.1073/pnas.1912684117] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Every cell produces thousands of lipid species, but studying the function of individual lipids in living cells is almost impossible with existing methodologies. Addressing this experimental bottleneck, we developed a strategy to quantify dissociation constants for lipid–protein interactions and transmembrane flip-flop rates of native lipids in live-cell experiments. Using a combination of plasma membrane-specific photochemical probes and mathematical modeling, we demonstrate that, for diacylglycerols as a model lipid class, the inherent lipid structural diversity caused by variations in acyl chain composition determines lipid protein affinities and transbilayer kinetics. In fact, subtle chemical differences change these values by orders of magnitude. Our approach represents a generally applicable method for elucidating the biological function of single lipid species on subcellular scales. Every cell produces thousands of distinct lipid species, but insight into how lipid chemical diversity contributes to biological signaling is lacking, particularly because of a scarcity of methods for quantitatively studying lipid function in living cells. Using the example of diacylglycerols, prominent second messengers, we here investigate whether lipid chemical diversity can provide a basis for cellular signal specification. We generated photo-caged lipid probes, which allow acute manipulation of distinct diacylglycerol species in the plasma membrane. Combining uncaging experiments with mathematical modeling, we were able to determine binding constants for diacylglycerol–protein interactions, and kinetic parameters for diacylglycerol transbilayer movement and turnover in quantitative live-cell experiments. Strikingly, we find that affinities and kinetics vary by orders of magnitude due to diacylglycerol side-chain composition. These differences are sufficient to explain differential recruitment of diacylglycerol binding proteins and, thus, differing downstream phosphorylation patterns. Our approach represents a generally applicable method for elucidating the biological function of single lipid species on subcellular scales in quantitative live-cell experiments.
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22
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Optical approaches for single-cell and subcellular analysis of GPCR-G protein signaling. Anal Bioanal Chem 2019; 411:4481-4508. [PMID: 30927013 DOI: 10.1007/s00216-019-01774-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Revised: 03/05/2019] [Accepted: 03/08/2019] [Indexed: 01/05/2023]
Abstract
G protein-coupled receptors (GPCRs), G proteins, and their signaling associates are major signal transducers that control the majority of cellular signaling and regulate key biological functions including immune, neurological, cardiovascular, and metabolic processes. These pathways are targeted by over one-third of drugs on the market; however, the current understanding of their function is limited and primarily derived from cell-destructive approaches providing an ensemble of static, multi-cell information about the status and composition of molecules. Spatiotemporal behavior of molecules involved is crucial to understanding in vivo cell behaviors both in health and disease, and the advent of genetically encoded fluorescence proteins and small fluorophore-based biosensors has facilitated the mapping of dynamic signaling in cells with subcellular acuity. Since we and others have developed optogenetic methods to regulate GPCR-G protein signaling in single cells and subcellular regions using dedicated wavelengths, the desire to develop and adopt optogenetically amenable assays to measure signaling has motivated us to take a broader look at the available optical tools and approaches compatible with measuring single-cell and subcellular GPCR-G protein signaling. Here we review such key optical approaches enabling the examination of GPCR, G protein, secondary messenger, and downstream molecules such as kinase and lipid signaling in living cells. The methods reviewed employ both fluorescence and bioluminescence detection. We not only further elaborate the underlying principles of these sensors but also discuss the experimental criteria and limitations to be considered during their use in single-cell and subcellular signal mapping.
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23
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Barger SR, Reilly NS, Shutova MS, Li Q, Maiuri P, Heddleston JM, Mooseker MS, Flavell RA, Svitkina T, Oakes PW, Krendel M, Gauthier NC. Membrane-cytoskeletal crosstalk mediated by myosin-I regulates adhesion turnover during phagocytosis. Nat Commun 2019; 10:1249. [PMID: 30890704 PMCID: PMC6425032 DOI: 10.1038/s41467-019-09104-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 02/21/2019] [Indexed: 11/09/2022] Open
Abstract
Phagocytosis of invading pathogens or cellular debris requires a dramatic change in cell shape driven by actin polymerization. For antibody-covered targets, phagocytosis is thought to proceed through the sequential engagement of Fc-receptors on the phagocyte with antibodies on the target surface, leading to the extension and closure of the phagocytic cup around the target. We find that two actin-dependent molecular motors, class 1 myosins myosin 1e and myosin 1f, are specifically localized to Fc-receptor adhesions and required for efficient phagocytosis of antibody-opsonized targets. Using primary macrophages lacking both myosin 1e and myosin 1f, we find that without the actin-membrane linkage mediated by these myosins, the organization of individual adhesions is compromised, leading to excessive actin polymerization, slower adhesion turnover, and deficient phagocytic internalization. This work identifies a role for class 1 myosins in coordinated adhesion turnover during phagocytosis and supports a mechanism involving membrane-cytoskeletal crosstalk for phagocytic cup closure.
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Affiliation(s)
- Sarah R Barger
- Cell and Developmental Biology Department, State University of New York Upstate Medical University, Syracuse, 13210, NY, USA
| | - Nicholas S Reilly
- Department of Physics, University of Rochester, Rochester, 14627, NY, USA
| | - Maria S Shutova
- Department of Biology, University of Pennsylvania, Philadelphia, 19104, PA, USA
| | - Qingsen Li
- IFOM, FIRC Institute of Molecular Oncology, Milan, 20139, Italy
| | - Paolo Maiuri
- IFOM, FIRC Institute of Molecular Oncology, Milan, 20139, Italy
| | - John M Heddleston
- Advanced Imaging Center, Howard Hughes Medical Institute Janelia Research Campus, Ashburn, 20147, VA, USA
| | - Mark S Mooseker
- Molecular, Cellular and Developmental Biology, Yale University, New Haven, 06520, CT, USA
| | - Richard A Flavell
- Department of Immunobiology, Yale University School of Medicine, New Haven, 06519, CT, USA
- Howard Hughes Medical Institute, Yale University, New Haven, 06519, CT, USA
| | - Tatyana Svitkina
- Department of Biology, University of Pennsylvania, Philadelphia, 19104, PA, USA
| | - Patrick W Oakes
- Department of Physics, University of Rochester, Rochester, 14627, NY, USA
- Department of Biology, University of Rochester, Rochester, 14627, NY, USA
| | - Mira Krendel
- Cell and Developmental Biology Department, State University of New York Upstate Medical University, Syracuse, 13210, NY, USA.
| | - Nils C Gauthier
- IFOM, FIRC Institute of Molecular Oncology, Milan, 20139, Italy.
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24
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Greenwald EC, Mehta S, Zhang J. Genetically Encoded Fluorescent Biosensors Illuminate the Spatiotemporal Regulation of Signaling Networks. Chem Rev 2018; 118:11707-11794. [PMID: 30550275 PMCID: PMC7462118 DOI: 10.1021/acs.chemrev.8b00333] [Citation(s) in RCA: 301] [Impact Index Per Article: 50.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cellular signaling networks are the foundation which determines the fate and function of cells as they respond to various cues and stimuli. The discovery of fluorescent proteins over 25 years ago enabled the development of a diverse array of genetically encodable fluorescent biosensors that are capable of measuring the spatiotemporal dynamics of signal transduction pathways in live cells. In an effort to encapsulate the breadth over which fluorescent biosensors have expanded, we endeavored to assemble a comprehensive list of published engineered biosensors, and we discuss many of the molecular designs utilized in their development. Then, we review how the high temporal and spatial resolution afforded by fluorescent biosensors has aided our understanding of the spatiotemporal regulation of signaling networks at the cellular and subcellular level. Finally, we highlight some emerging areas of research in both biosensor design and applications that are on the forefront of biosensor development.
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Affiliation(s)
- Eric C Greenwald
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
| | - Sohum Mehta
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
| | - Jin Zhang
- University of California , San Diego, 9500 Gilman Drive, BRFII , La Jolla , CA 92093-0702 , United States
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25
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Tolstykh GP, Cantu JC, Tarango M, Ibey BL. Receptor- and store-operated mechanisms of calcium entry during the nanosecond electric pulse-induced cellular response. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1861:685-696. [PMID: 30552899 DOI: 10.1016/j.bbamem.2018.12.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 12/07/2018] [Accepted: 12/10/2018] [Indexed: 11/16/2022]
Abstract
Nanosecond electric pulses have been shown to open nanopores in the cell plasma membrane by fluorescent imaging of calcium uptake and fluorescent dyes, including propidium (Pr) iodide and YO-PRO-1 (YP1). Recently, we demonstrated that nsEPs also induce the phosphoinositide intracellular signaling cascade by phosphatidylinositol-4,5-bisphosphate (PIP2) depletion resulting in physiological responses similar to those observed following stimulation of Gq11-coupled receptors. In this paper, we explore the role of receptor- and store-operated calcium entry (ROCE/SOCE) mechanisms in the observed response of cells to nsEP. We show that addition of the ROCE/SOCE and transient receptor potential channel (TRPC) blocker gadolinium (Gd3+, 300 μM) slows PIP2 depletion following 1 and 20 nsEP exposures. Lipid rafts, regions of the plasma membrane rich in PIP2 and TRPC, are also disrupted by nsEP exposure suggesting that ROCE/SOCE mechanisms are likely impacted. Reducing the expression of stromal interaction molecule 1 (STIM1) protein, a key protein in ROCE and SOCE, in cells exposure to nsEP resulted in a reduction in induced intracellular calcium rise. Additionally, after exposure to 1 and 20 nsEPs (16.2 kV/cm, 5 Hz), intracellular calcium rises were significantly reduced by the addition of GD3+ and SKF-96365 (1-[2-(4-methoxyphenyl)-2-[3-(4-methoxyphenyl) propoxy] ethyl-1H-imidazole hydrochloride, 100 μM), a blocker of STIM1 interaction. However, using similar nsEP exposure parameters, SKF-96365 was less effective at reducing YP1 uptake compared to Gd3+. Thus, it is possible that SKF-96365 could block STIM1 interactions within the cell, while Gd3+ could acts on TRPC/nanopores from outside of the cell. Our results present evidence of nsEP induces ROCE and SOCE mechanisms and demonstrate that YP1 and Ca2+ cannot be used solely as markers of nsEP-induced nanoporation.
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Affiliation(s)
- Gleb P Tolstykh
- General Dynamics Information Technology, 4141 Petroleum Road, JBSA Fort Sam Houston, TX 78234, USA.
| | - Jody C Cantu
- General Dynamics Information Technology, 4141 Petroleum Road, JBSA Fort Sam Houston, TX 78234, USA
| | - Melissa Tarango
- General Dynamics Information Technology, 4141 Petroleum Road, JBSA Fort Sam Houston, TX 78234, USA
| | - Bennett L Ibey
- Air Force Research Laboratory, 711th Human Performance Wing, Airman Systems Directorate, Bioeffects Division, Radio Frequency Bioeffects Branch, 4141 Petroleum Road, JBSA Fort Sam Houston, TX 78234, USA
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26
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Role of Zinc Signaling in the Regulation of Mast Cell-, Basophil-, and T Cell-Mediated Allergic Responses. J Immunol Res 2018; 2018:5749120. [PMID: 30596108 PMCID: PMC6286780 DOI: 10.1155/2018/5749120] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Accepted: 10/23/2018] [Indexed: 01/26/2023] Open
Abstract
Zinc is essential for maintaining normal structure and physiological function of cells. Its deficiency causes growth retardation, immunodeficiency, and neuronal degeneration. Zinc homeostasis is tightly regulated by zinc transporters and metallothioneins that control zinc concentration and its distribution in individual cells and contributes to zinc signaling. The intracellular zinc signaling regulates immune reactions. Although many molecules involved in these processes have zinc-binding motifs, the molecular mechanisms and the role of zinc in immune responses have not been elucidated. We and others have demonstrated that zinc signaling plays diverse and specific roles in vivo and in vitro in studies using knockout mice lacking zinc transporter function and metallothionein function. In this review, we discuss the impact of zinc signaling focusing particularly on mast cell-, basophil-, and T cell-mediated inflammatory and allergic responses. We also describe zinc signaling dysregulation as a leading health problem in inflammatory disease and allergy.
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27
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Krishnamoorthy M, Wasim L, Buhari FHM, Zhao T, Mahtani T, Ho J, Kang S, Deason-Towne F, Perraud AL, Schmitz C, Treanor B. The channel-kinase TRPM7 regulates antigen gathering and internalization in B cells. Sci Signal 2018; 11:11/533/eaah6692. [PMID: 29871912 DOI: 10.1126/scisignal.aah6692] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Members of the transient receptor potential (TRP) family of ion channels are cellular sensors involved in numerous physiological and pathological processes. We identified the TRP subfamily M member 7 (TRPM7) channel-kinase as a previously uncharacterized regulator of B cell activation. We showed that TRPM7 played a critical role in the early events of B cell activation through both its ion channel and kinase functions. DT40 B cells deficient in TRPM7 or expressing a kinase-deficient mutant of TRPM7 showed defective gathering of antigen and prolonged B cell receptor (BCR) signaling. We showed that lipid metabolism was altered in TRPM7-deficient cells and in cells expressing a kinase-deficient mutant of TRPM7 and suggest that PLC-γ2 may be a target of the kinase activity of TRPM7. Primary B cells that expressed less TRPM7 or were treated with a pharmacological inhibitor of TRPM7 also displayed defective antigen gathering and increased BCR signaling. Finally, we demonstrated that blocking TRPM7 function compromised antigen internalization and presentation to T cells. These data suggest that TRPM7 controls an essential process required for B cell affinity maturation and the production of high-affinity antibodies.
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Affiliation(s)
- Mithunah Krishnamoorthy
- Department of Cell and Systems Biology, University of Toronto, 24 Harbord Street, Toronto, Ontario M5S 3G5, Canada
| | - Laabiah Wasim
- Department of Immunology, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Fathima Hifza Mohamed Buhari
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada
| | - Tiantian Zhao
- Department of Immunology, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Trisha Mahtani
- Department of Cell and Systems Biology, University of Toronto, 24 Harbord Street, Toronto, Ontario M5S 3G5, Canada
| | - Josephine Ho
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada
| | - Sohee Kang
- Department of Computer and Mathematical Sciences, University of Toronto Scarborough, Toronto, Ontario M1C 1A4, Canada
| | - Francina Deason-Towne
- Department of Immunology and Microbiology, University of Colorado, Denver, CO 80206, USA
| | - Anne-Laure Perraud
- Department of Immunology and Microbiology, University of Colorado, Denver, CO 80206, USA
| | - Carsten Schmitz
- Department of Immunology and Microbiology, University of Colorado, Denver, CO 80206, USA.,Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
| | - Bebhinn Treanor
- Department of Cell and Systems Biology, University of Toronto, 24 Harbord Street, Toronto, Ontario M5S 3G5, Canada. .,Department of Immunology, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada.,Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada
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28
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Munanairi A, Liu XY, Barry DM, Yang Q, Yin JB, Jin H, Li H, Meng QT, Peng JH, Wu ZY, Yin J, Zhou XY, Wan L, Mo P, Kim S, Huo FQ, Jeffry J, Li YQ, Bardoni R, Bruchas MR, Chen ZF. Non-canonical Opioid Signaling Inhibits Itch Transmission in the Spinal Cord of Mice. Cell Rep 2018; 23:866-877. [PMID: 29669290 PMCID: PMC5937707 DOI: 10.1016/j.celrep.2018.03.087] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 02/28/2018] [Accepted: 03/20/2018] [Indexed: 01/20/2023] Open
Abstract
Chronic itch or pruritus is a debilitating disorder that is refractory to conventional anti-histamine treatment. Kappa opioid receptor (KOR) agonists have been used to treat chronic itch, but the underlying mechanism remains elusive. Here, we find that KOR and gastrin-releasing peptide receptor (GRPR) overlap in the spinal cord, and KOR activation attenuated GRPR-mediated histamine-independent acute and chronic itch in mice. Notably, canonical KOR-mediated Gαi signaling is not required for desensitizing GRPR function. In vivo and in vitro studies suggest that KOR activation results in the translocation of Ca2+-independent protein kinase C (PKC)δ from the cytosol to the plasma membrane, which in turn phosphorylates and inhibits GRPR activity. A blockade of phospholipase C (PLC) in HEK293 cells prevented KOR-agonist-induced PKCδ translocation and GRPR phosphorylation, suggesting a role of PLC signaling in KOR-mediated GRPR desensitization. These data suggest that a KOR-PLC-PKCδ-GRPR signaling pathway in the spinal cord may underlie KOR-agonists-induced anti-pruritus therapies.
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MESH Headings
- Animals
- Cell Membrane/metabolism
- Chloroquine/toxicity
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- HEK293 Cells
- Humans
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Phosphorylation
- Protein Kinase C-delta/antagonists & inhibitors
- Protein Kinase C-delta/genetics
- Protein Kinase C-delta/metabolism
- Pruritus/chemically induced
- Pruritus/pathology
- RNA Interference
- RNA, Small Interfering/metabolism
- Receptors, Bombesin/metabolism
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/deficiency
- Receptors, Opioid, kappa/genetics
- Signal Transduction
- Spinal Cord/metabolism
- Type C Phospholipases/antagonists & inhibitors
- Type C Phospholipases/metabolism
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Affiliation(s)
- Admire Munanairi
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Xian-Yu Liu
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Devin M Barry
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Qianyi Yang
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jun-Bin Yin
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anatomy and K. K. Leung Brain Research Centre, The Fourth Military Medical University, 710032 Xi'an, PRC
| | - Hua Jin
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Hui Li
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anatomy and K. K. Leung Brain Research Centre, The Fourth Military Medical University, 710032 Xi'an, PRC
| | - Qing-Tao Meng
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jia-Hang Peng
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Zhen-Yu Wu
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anatomy and K. K. Leung Brain Research Centre, The Fourth Military Medical University, 710032 Xi'an, PRC
| | - Jun Yin
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Xuan-Yi Zhou
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Li Wan
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anatomy and K. K. Leung Brain Research Centre, The Fourth Military Medical University, 710032 Xi'an, PRC
| | - Ping Mo
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anatomy and K. K. Leung Brain Research Centre, The Fourth Military Medical University, 710032 Xi'an, PRC
| | - Seungil Kim
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Fu-Quan Huo
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Joseph Jeffry
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Yun-Qing Li
- Department of Anatomy and K. K. Leung Brain Research Centre, The Fourth Military Medical University, 710032 Xi'an, PRC; Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, PRC
| | - Rita Bardoni
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena 41125, Italy
| | - Michael R Bruchas
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Zhou-Feng Chen
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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29
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Frank JA, Yushchenko DA, Fine NHF, Duca M, Citir M, Broichhagen J, Hodson DJ, Schultz C, Trauner D. Optical control of GPR40 signalling in pancreatic β-cells. Chem Sci 2017; 8:7604-7610. [PMID: 29568424 PMCID: PMC5848828 DOI: 10.1039/c7sc01475a] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Accepted: 08/29/2017] [Indexed: 01/04/2023] Open
Abstract
Fatty acids activate GPR40 and K+ channels to modulate β-cell function. Herein, we describe the design and synthesis of FAAzo-10, a light-controllable GPR40 agonist based on Gw-9508. FAAzo-10 is a potent GPR40 agonist in the trans-configuration and can be inactivated on isomerization to cis with UV-A light. Irradiation with blue light reverses this effect, allowing FAAzo-10 activity to be cycled ON and OFF with a high degree of spatiotemporal precision. In dissociated primary mouse β-cells, FAAzo-10 also inactivates voltage-activated and ATP-sensitive K+ channels, and allows us to control glucose-stimulated Ca2+ oscillations in whole islets with light. As such, FAAzo-10 is a useful tool to study the complex effects, with high specificity, which FA-derivatives such as Gw-9508 exert at multiple targets in mouse β-cells.
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Affiliation(s)
- James Allen Frank
- Department of Chemistry , Center for Integrated Protein Science , Ludwig Maximilians University Munich , Butenandtstraße 5-13 , 81377 Munich , Germany
| | - Dmytro A Yushchenko
- European Molecular Biology Laboratory (EMBL) , Cell Biology & Biophysics Unit , Meyerhofstraße 1 , 69117 Heidelberg , Germany .
- Institute of Organic Chemistry and Biochemistry , Academy of Sciences of the Czech Republic , Flemingovo namesti 2 , 16610 Prague 6 , Czech Republic
| | - Nicholas H F Fine
- Institute of Metabolism and Systems Research (IMSR) , University of Birmingham , Birmingham , B15 2TT , UK .
- Centre for Endocrinology, Diabetes and Metabolism , Birmingham Health Partners , Birmingham , B15 2TH , UK
- COMPARE University of Birmingham and University of Nottingham Midlands , UK
| | - Margherita Duca
- Department of Chemistry , Center for Integrated Protein Science , Ludwig Maximilians University Munich , Butenandtstraße 5-13 , 81377 Munich , Germany
- Department of Chemistry , University of Milan , Via Golgi 19 , 20133 , Milan , Italy
| | - Mevlut Citir
- European Molecular Biology Laboratory (EMBL) , Cell Biology & Biophysics Unit , Meyerhofstraße 1 , 69117 Heidelberg , Germany .
| | - Johannes Broichhagen
- Department of Chemistry , Center for Integrated Protein Science , Ludwig Maximilians University Munich , Butenandtstraße 5-13 , 81377 Munich , Germany
- Max-Planck Institute of Medical Research , Jahnstr. 29 , 69120 Heidelberg , Germany
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR) , University of Birmingham , Birmingham , B15 2TT , UK .
- Centre for Endocrinology, Diabetes and Metabolism , Birmingham Health Partners , Birmingham , B15 2TH , UK
- COMPARE University of Birmingham and University of Nottingham Midlands , UK
| | - Carsten Schultz
- European Molecular Biology Laboratory (EMBL) , Cell Biology & Biophysics Unit , Meyerhofstraße 1 , 69117 Heidelberg , Germany .
- Dept. of Physiology and Pharmacology , Oregon Health and Science University , Portland , OR 97237 , USA
| | - Dirk Trauner
- Department of Chemistry , Center for Integrated Protein Science , Ludwig Maximilians University Munich , Butenandtstraße 5-13 , 81377 Munich , Germany
- Department of Chemistry , New York University , 100 Washington Square East , New York , NY 10003-6699 , USA .
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30
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Li Z, Xie J, Peng S, Liu S, Wang Y, Lu W, Shen J, Li C. Novel Strategy Utilizing Extracellular Cysteine-Rich Domain of Membrane Receptor for Constructing d-Peptide Mediated Targeted Drug Delivery Systems: A Case Study on Fn14. Bioconjug Chem 2017; 28:2167-2179. [DOI: 10.1021/acs.bioconjchem.7b00326] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zhuoxuan Li
- College
of Pharmaceutical Sciences, Southwest University, Chongqing, 400715, PR China
| | - Jing Xie
- College
of Pharmaceutical Sciences, Southwest University, Chongqing, 400715, PR China
| | - Shan Peng
- College
of Pharmaceutical Sciences, Southwest University, Chongqing, 400715, PR China
| | - Sha Liu
- College
of Pharmaceutical Sciences, Southwest University, Chongqing, 400715, PR China
| | - Ying Wang
- College
of Pharmaceutical Sciences, Southwest University, Chongqing, 400715, PR China
| | - Weiyue Lu
- School
of Pharmacy, Key Laboratory of Smart Drug Delivery, Ministry of Education, Fudan University, Shanghai 201203, PR China
| | - Jie Shen
- College
of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Chong Li
- College
of Pharmaceutical Sciences, Southwest University, Chongqing, 400715, PR China
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31
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Vermeer JE, van Wijk R, Goedhart J, Geldner N, Chory J, Gadella TW, Munnik T. In Vivo Imaging of Diacylglycerol at the Cytoplasmic Leaflet of Plant Membranes. PLANT & CELL PHYSIOLOGY 2017; 58:1196-1207. [PMID: 28158855 PMCID: PMC6200129 DOI: 10.1093/pcp/pcx012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Accepted: 01/11/2017] [Indexed: 05/05/2023]
Abstract
Diacylglycerol (DAG) is an important intermediate in lipid biosynthesis and plays key roles in cell signaling, either as a second messenger itself or as a precursor of phosphatidic acid. Methods to identify distinct DAG pools have proven difficult because biochemical fractionation affects the pools, and concentrations are limiting. Here, we validate the use of a genetically encoded DAG biosensor in living plant cells. The sensor is composed of a fusion between yellow fluorescent protein and the C1a domain of protein kinase C (YFP-C1aPKC) that specifically binds DAG, and was stably expressed in suspension-cultured tobacco BY-2 cells and whole Arabidopsis thaliana plants. Confocal imaging revealed that the majority of the YFP-C1aPKC fluorescence did not locate to membranes but was present in the cytosol and nucleus. Treatment with short-chain DAG or PMA (phorbol-12-myristate-13-acetate), a phorbol ester that binds the C1a domain of PKC, caused the recruitment of the biosensor to the plasma membrane. These results indicate that the biosensor works and that the basal DAG concentration in the cytoplasmic leaflet of membranes (i.e. accessible to the biosensor) is in general too low, and confirms that the known pools in plastids, the endoplasmic reticulum and mitochondria are located at the luminal face of these compartments (i.e. inaccessible to the biosensor). Nevertheless, detailed further analysis of different cells and tissues discovered four novel DAG pools, namely at: (i) the trans-Golgi network; (ii) the cell plate during cytokinesis; (iii) the plasma membrane of root epidermal cells in the transition zone, and (iv) the apex of growing root hairs. The results provide new insights into the spatiotemporal dynamics of DAG in plants and offer a new tool to monitor this in vivo.
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Affiliation(s)
- Joop E.M. Vermeer
- Section of Plant Physiology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, NL-1098XH, Amsterdam, The Netherlands
- Department of Plant Molecular Biology, University of Lausanne-Sorge, Lausanne 1015, Switzerland
- Present address: Department of Plant and Microbial Biology, University of Zürich, Zürich 8008, Switzerland
| | - Ringo van Wijk
- Section of Plant Physiology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, NL-1098XH, Amsterdam, The Netherlands
- Section of Plant Cell Biology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, NL-1098XH, Amsterdam, The Netherlands
| | - Joachim Goedhart
- Section of Molecular Cytology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, NL-1098XH, Amsterdam, The Netherlands
| | - Niko Geldner
- Department of Plant Molecular Biology, University of Lausanne-Sorge, Lausanne 1015, Switzerland
| | - Joanne Chory
- Plant Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Theodorus W.J. Gadella
- Section of Molecular Cytology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, NL-1098XH, Amsterdam, The Netherlands
| | - Teun Munnik
- Section of Plant Physiology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, NL-1098XH, Amsterdam, The Netherlands
- Section of Plant Cell Biology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, NL-1098XH, Amsterdam, The Netherlands
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32
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Hirano T, Stecker K, Munnik T, Xu H, Sato MH. Visualization of Phosphatidylinositol 3,5-Bisphosphate Dynamics by a Tandem ML1N-Based Fluorescent Protein Probe in Arabidopsis. PLANT & CELL PHYSIOLOGY 2017; 58:1185-1195. [PMID: 28158631 PMCID: PMC5921506 DOI: 10.1093/pcp/pcx011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Accepted: 01/13/2017] [Indexed: 05/24/2023]
Abstract
Phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2] is a low-abundance phospholipid known to be associated with a wide variety of physiological functions in plants. However, the localization and dynamics of PI(3,5)P2 in plant cells remain largely unknown, partially due to the lack of an effective fluorescent probe. Using Arabidopsis transgenic plant expressing the PI(3,5)P2-labeling fluorescent probe (tagRFP-ML1N*2) developed based on a tandem repeat of the cytosolic phosphoinositide-interacting domain (ML1N) of the mammalian lysosomal transient receptor potential cation channel, Mucolipin 1 (TRPML1), here we show that PI(3,5)P2 is predominantly localized on the limited membranes of the FAB1- and SNX1-positive late endosomes, but rarely localized on the membranes of plant vacuoles or trans-Golgi network/early endosomes of cortical cells of the root differentiation zone. The late endosomal localization of tagRFP-ML1N*2 is reduced or abolished by pharmacological inhibition or genetic knockdown of expression of genes encoding PI(3,5)P2-synthesizing enzymes, FAB1A/B, but markedly increased with FAB1A overexpression. Notably, reactive oxygen species (ROS) significantly increase late endosomal levels of PI(3,5)P2. Thus, tandem ML1N-based PI(3,5)P2 probes can reliably monitor intracellular dynamics of PI(3,5)P2 in Arabidopsis cells with less binding activity to other endomembrane organelles.
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Affiliation(s)
- Tomoko Hirano
- Laboratory of Cellular Dynamics, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Shimogamo-nakaragi-cho, Sakyo-ku, Kyoto, 606-8522 Japan
| | - Kelly Stecker
- Biotechnology Center, University of Wisconsin, Madison, WI 53706, USA
| | - Teun Munnik
- Section of Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science park 904, 1098 XH Amsterdam 94216, The Netherlands
| | - Haoxing Xu
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Masa H. Sato
- Laboratory of Cellular Dynamics, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Shimogamo-nakaragi-cho, Sakyo-ku, Kyoto, 606-8522 Japan
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33
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York N, Halbach P, Chiu MA, Bird IM, Pillers DAM, Pattnaik BR. Oxytocin (OXT)-stimulated inhibition of Kir7.1 activity is through PIP 2-dependent Ca 2+ response of the oxytocin receptor in the retinal pigment epithelium in vitro. Cell Signal 2017; 37:93-102. [PMID: 28603013 DOI: 10.1016/j.cellsig.2017.06.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 05/28/2017] [Accepted: 06/05/2017] [Indexed: 01/26/2023]
Abstract
Oxytocin (OXT) is a neuropeptide that activates the oxytocin receptor (OXTR), a rhodopsin family G-protein coupled receptor. Our localization of OXTR to the retinal pigment epithelium (RPE), in close proximity to OXT in the adjacent photoreceptor neurons, leads us to propose that OXT plays an important role in RPE-retinal communication. An increase of RPE [Ca2+]i in response to OXT stimulation implies that the RPE may utilize oxytocinergic signaling as a mechanism by which it accomplishes some of its many roles. In this study, we used an established human RPE cell line, a HEK293 heterologous OXTR expression system, and pharmacological inhibitors of Ca2+ signaling to demonstrate that OXTR utilizes capacitative Ca2+ entry (CCE) mechanisms to sustain an increase in cytoplasmic Ca2+. These findings demonstrate how multiple functional outcomes of OXT-OXTR signaling could be integrated via a single pathway. In addition, the activated OXTR was able to inhibit the Kir7.1 channel, an important mediator of sub retinal waste transport and K+ homeostasis.
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Affiliation(s)
- Nathaniel York
- Endocrinology-Reproductive Physiology Program, The University of Wisconsin, Madison, WI 53715, United States; Division of Neonatology& Newborn Nursery, The University of Wisconsin, Madison, WI 53715, United States; Departments of Pediatrics, The University of Wisconsin, Madison, WI 53715, United States; The McPherson Eye Research Institute, The University of Wisconsin, Madison, WI 53715, United States
| | - Patrick Halbach
- Endocrinology-Reproductive Physiology Program, The University of Wisconsin, Madison, WI 53715, United States; Division of Neonatology& Newborn Nursery, The University of Wisconsin, Madison, WI 53715, United States; Departments of Pediatrics, The University of Wisconsin, Madison, WI 53715, United States; The McPherson Eye Research Institute, The University of Wisconsin, Madison, WI 53715, United States
| | - Michelle A Chiu
- Division of Neonatology& Newborn Nursery, The University of Wisconsin, Madison, WI 53715, United States; Departments of Pediatrics, The University of Wisconsin, Madison, WI 53715, United States; The McPherson Eye Research Institute, The University of Wisconsin, Madison, WI 53715, United States
| | - Ian M Bird
- Endocrinology-Reproductive Physiology Program, The University of Wisconsin, Madison, WI 53715, United States; Obstetrics & Gynecology, The University of Wisconsin, Madison, WI 53715, United States
| | - De-Ann M Pillers
- Division of Neonatology& Newborn Nursery, The University of Wisconsin, Madison, WI 53715, United States; Departments of Pediatrics, The University of Wisconsin, Madison, WI 53715, United States; Medical Genetics, The University of Wisconsin, Madison, WI 53715, United States; The McPherson Eye Research Institute, The University of Wisconsin, Madison, WI 53715, United States
| | - Bikash R Pattnaik
- Endocrinology-Reproductive Physiology Program, The University of Wisconsin, Madison, WI 53715, United States; Division of Neonatology& Newborn Nursery, The University of Wisconsin, Madison, WI 53715, United States; Departments of Pediatrics, The University of Wisconsin, Madison, WI 53715, United States; Ophthalmology &Visual Sciences, The University of Wisconsin, Madison, WI 53715, United States; The McPherson Eye Research Institute, The University of Wisconsin, Madison, WI 53715, United States.
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34
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Mason JW, Schmid CL, Bohn LM, Roush WR. Stolonidiol: Synthesis, Target Identification, and Mechanism for Choline Acetyltransferase Activation. J Am Chem Soc 2017; 139:5865-5869. [PMID: 28414442 DOI: 10.1021/jacs.7b01083] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Stolonidiol, a marine natural product, has been reported to potentiate the activity of choline acetyltransferase (ChAT), the enzyme that produces the neurotransmitter acetylcholine. Here we report the total synthesis of stolonidiol starting from (R)-(+)-limonene. To identify the mechanism by which ChAT activity is increased, we sought to identify the biological target of stolonidiol. We show that stolonidiol binds to the phorbol ester binding site of protein kinase C (PKC), induces translocation of PKC to the cell membrane, and activates kinase activity. Furthermore, we confirmed the increase in ChAT activity observed upon treatment of cells with stolonidiol and show that this effect is mediated by PKC. Collectively, our data strongly suggest that PKC activation by stolonidiol is responsible for the resulting potentiation of ChAT activity.
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Affiliation(s)
- Jeremy W Mason
- Department of Chemistry and ‡Department of Molecular Therapeutics, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Cullen L Schmid
- Department of Chemistry and ‡Department of Molecular Therapeutics, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Laura M Bohn
- Department of Chemistry and ‡Department of Molecular Therapeutics, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
| | - William R Roush
- Department of Chemistry and ‡Department of Molecular Therapeutics, The Scripps Research Institute , 130 Scripps Way, Jupiter, Florida 33458, United States
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35
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Tolstykh GP, Olsovsky CA, Ibey BL, Beier HT. Ryanodine and IP 3 receptor-mediated calcium signaling play a pivotal role in neurological infrared laser modulation. NEUROPHOTONICS 2017; 4:025001. [PMID: 28413806 PMCID: PMC5381754 DOI: 10.1117/1.nph.4.2.025001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 03/20/2017] [Indexed: 05/13/2023]
Abstract
Pulsed infrared (IR) laser energy has been shown to modulate neurological activity through both stimulation and inhibition of action potentials. While the mechanism(s) behind this phenomenon is (are) not completely understood, certain hypotheses suggest that the rise in temperature from IR exposure could activate temperature- or pressure-sensitive ion channels or create pores in the cellular outer membrane, allowing an influx of typically plasma-membrane-impermeant ions. Studies using fluorescent intensity-based calcium ion ([Formula: see text]) sensitive dyes show changes in [Formula: see text] levels after various IR stimulation parameters, which suggests that [Formula: see text] may originate from the external solution. However, activation of intracellular signaling pathways has also been demonstrated, indicating a more complex mechanism of increasing intracellular [Formula: see text] concentration. We quantified the [Formula: see text] mobilization in terms of influx from the external solution and efflux from intracellular organelles using Fura-2 and a high-speed ratiometric imaging system that rapidly alternates the dye excitation wavelengths. Using nonexcitable Chinese hamster ovarian ([Formula: see text]) cells and neuroblastoma-glioma (NG108) cells, we demonstrate that intracellular [Formula: see text] receptors play an important role in the IR-induced [Formula: see text], with the [Formula: see text] response augmented by ryanodine receptors in excitable cells.
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Affiliation(s)
- Gleb P. Tolstykh
- General Dynamics Information Technology, JBSA Fort Sam Houston, San Antonio, Texas, United States
- Address all correspondence to: Gleb P. Tolstykh, E-mail:
| | - Cory A. Olsovsky
- Texas A&M University, Department of Biomedical Engineering, College Station, Texas, United States
| | - Bennett L. Ibey
- Air Force Research Laboratory, 711th Human Performance Wing, Airman Systems Directorate, Bioeffects Division, Radio Frequency Bioeffects Branch, JBSA Fort Sam Houston, San Antonio, Texas, United States
| | - Hope T. Beier
- Air Force Research Laboratory, 711th Human Performance Wing, Airman System Directorate, Bioeffects Division, Optical Radiation Bioeffects Branch, JBSA Fort Sam Houston, San Antonio, Texas, United States
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36
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Tolstykh GP, Tarango M, Roth CC, Ibey BL. Nanosecond pulsed electric field induced dose dependent phosphatidylinositol-4,5-bisphosphate signaling and intracellular electro-sensitization. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:438-445. [DOI: 10.1016/j.bbamem.2017.01.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 12/15/2016] [Accepted: 01/02/2017] [Indexed: 12/11/2022]
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Várnai P, Gulyás G, Tóth DJ, Sohn M, Sengupta N, Balla T. Quantifying lipid changes in various membrane compartments using lipid binding protein domains. Cell Calcium 2016; 64:72-82. [PMID: 28088320 DOI: 10.1016/j.ceca.2016.12.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 12/28/2016] [Accepted: 12/29/2016] [Indexed: 11/30/2022]
Abstract
One of the largest challenges in cell biology is to map the lipid composition of the membranes of various organelles and define the exact location of processes that control the synthesis and distribution of lipids between cellular compartments. The critical role of phosphoinositides, low-abundant lipids with rapid metabolism and exceptional regulatory importance in the control of almost all aspects of cellular functions created the need for tools to visualize their localizations and dynamics at the single cell level. However, there is also an increasing need for methods to determine the cellular distribution of other lipids regulatory or structural, such as diacylglycerol, phosphatidic acid, or other phospholipids and cholesterol. This review will summarize recent advances in this research field focusing on the means by which changes can be described in more quantitative terms.
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Affiliation(s)
- Péter Várnai
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Gergő Gulyás
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Dániel J Tóth
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States; Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Mira Sohn
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States
| | - Nivedita Sengupta
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States
| | - Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States.
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Jung SR, Seo JB, Deng Y, Asbury CL, Hille B, Koh DS. Contributions of protein kinases and β-arrestin to termination of protease-activated receptor 2 signaling. ACTA ACUST UNITED AC 2016; 147:255-71. [PMID: 26927499 PMCID: PMC4772372 DOI: 10.1085/jgp.201511477] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Systematic imaging studies and modeling reveal new details of the regulation of the Gq-coupled GPCR, protease-activated receptor 2, by phosphorylation and β-arrestin. Activated Gq protein–coupled receptors (GqPCRs) can be desensitized by phosphorylation and β-arrestin binding. The kinetics and individual contributions of these two mechanisms to receptor desensitization have not been fully distinguished. Here, we describe the shut off of protease-activated receptor 2 (PAR2). PAR2 activates Gq and phospholipase C (PLC) to hydrolyze phosphatidylinositol 4,5-bisphosphate (PIP2) into diacylglycerol and inositol trisphosphate (IP3). We used fluorescent protein–tagged optical probes to monitor several consequences of PAR2 signaling, including PIP2 depletion and β-arrestin translocation in real time. During continuous activation of PAR2, PIP2 was depleted transiently and then restored within a few minutes, indicating fast receptor activation followed by desensitization. Knockdown of β-arrestin 1 and 2 using siRNA diminished the desensitization, slowing PIP2 restoration significantly and even adding a delayed secondary phase of further PIP2 depletion. These effects of β-arrestin knockdown on PIP2 recovery were prevented when serine/threonine phosphatases that dephosphorylate GPCRs were inhibited. Thus, PAR2 may continuously regain its activity via dephosphorylation when there is insufficient β-arrestin to trap phosphorylated receptors. Similarly, blockers of protein kinase C (PKC) and G protein–coupled receptor kinase potentiated the PIP2 depletion. In contrast, an activator of PKC inhibited receptor activation, presumably by augmenting phosphorylation of PAR2. Our interpretations were strengthened by modeling. Simulations supported the conclusions that phosphorylation of PAR2 by protein kinases initiates receptor desensitization and that recruited β-arrestin traps the phosphorylated state of the receptor, protecting it from phosphatases. Speculative thinking suggested a sequestration of phosphatidylinositol 4-phosphate 5 kinase (PIP5K) to the plasma membrane by β-arrestin to explain why knockdown of β-arrestin led to secondary depletion of PIP2. Indeed, artificial recruitment of PIP5K removed the secondary loss of PIP2 completely. Altogether, our experimental and theoretical approaches demonstrate roles and dynamics of the protein kinases, β-arrestin, and PIP5K in the desensitization of PAR2.
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Affiliation(s)
- Seung-Ryoung Jung
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Jong Bae Seo
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Yi Deng
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Charles L Asbury
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Bertil Hille
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Duk-Su Koh
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195 Department of Physics, Pohang University of Science and Technology, Pohang, Kyungbuk, 790-784, Republic of Korea
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Abstract
Membrane lipids are dynamic molecules and their local concentrations serve as regulatory signals for diverse biological processes. To achieve quantitative in situ imaging of various lipids, we developed a ratiometric analysis using fluorescence biosensors, each of which is composed of an engineered lipid-binding protein and a covalently attached solvatochromic fluorophore. To cover a wide range of lipid concentration, lipid-binding proteins are engineered to have variable dynamic ranges. These tunable sensors allow robust and sensitive in situ quantitative lipid imaging in mammalian cells, providing new insight into the spatiotemporal dynamics and fluctuation of key signaling lipids. The sensor strategy is also applicable to in situ quantification of multiple cellular lipids or a single lipid in the opposing leaflets of cell membranes.
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Frank JA, Yushchenko DA, Hodson DJ, Lipstein N, Nagpal J, Rutter GA, Rhee JS, Gottschalk A, Brose N, Schultz C, Trauner D. Photoswitchable diacylglycerols enable optical control of protein kinase C. Nat Chem Biol 2016; 12:755-62. [PMID: 27454932 PMCID: PMC6101201 DOI: 10.1038/nchembio.2141] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 05/16/2016] [Indexed: 01/02/2023]
Abstract
Increased levels of the second messenger lipid diacylglycerol (DAG) induce downstream signaling events including the translocation of C1-domain-containing proteins toward the plasma membrane. Here, we introduce three light-sensitive DAGs, termed PhoDAGs, which feature a photoswitchable acyl chain. The PhoDAGs are inactive in the dark and promote the translocation of proteins that feature C1 domains toward the plasma membrane upon a flash of UV-A light. This effect is quickly reversed after the termination of photostimulation or by irradiation with blue light, permitting the generation of oscillation patterns. Both protein kinase C and Munc13 can thus be put under optical control. PhoDAGs control vesicle release in excitable cells, such as mouse pancreatic islets and hippocampal neurons, and modulate synaptic transmission in Caenorhabditis elegans. As such, the PhoDAGs afford an unprecedented degree of spatiotemporal control and are broadly applicable tools to study DAG signaling.
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Affiliation(s)
- James Allen Frank
- Department of Chemistry and Center for Integrated Protein Science, Ludwig Maximilians University Munich, Munich, Germany
| | - Dmytro A Yushchenko
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - David J Hodson
- Section of Cell Biology and Functional Genomics, Department of Medicine, Imperial College London, ICTEM, Hammersmith Hospital, London, UK
- Institute of Metabolism and Systems Research (IMSR) and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK
- Centre for Endocrinology, Diabetes and Metabolism (CEDAM), Birmingham Health Partners, Birmingham, UK
| | - Noa Lipstein
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Jatin Nagpal
- Buchmann Institute for Molecular Life Sciences, Goethe University, Frankfurt, Germany
- Institute of Biochemistry, Department for Biochemistry, Chemistry and Pharmacy, Goethe University, Frankfurt, Germany
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Department of Medicine, Imperial College London, ICTEM, Hammersmith Hospital, London, UK
| | - Jeong-Seop Rhee
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Alexander Gottschalk
- Buchmann Institute for Molecular Life Sciences, Goethe University, Frankfurt, Germany
- Institute of Biochemistry, Department for Biochemistry, Chemistry and Pharmacy, Goethe University, Frankfurt, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Carsten Schultz
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Dirk Trauner
- Department of Chemistry and Center for Integrated Protein Science, Ludwig Maximilians University Munich, Munich, Germany
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Heilmann I, Ischebeck T. Male functions and malfunctions: the impact of phosphoinositides on pollen development and pollen tube growth. PLANT REPRODUCTION 2016; 29:3-20. [PMID: 26676144 DOI: 10.1007/s00497-015-0270-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Accepted: 11/17/2015] [Indexed: 05/12/2023]
Abstract
Phosphoinositides in pollen. In angiosperms, sexual reproduction is a series of complex biological events that facilitate the distribution of male generative cells for double fertilization. Angiosperms have no motile gametes, and the distribution units of generative cells are pollen grains, passively mobile desiccated structures, capable of delivering genetic material to compatible flowers over long distances and in an adverse environment. The development of pollen (male gametogenesis) and the formation of a pollen tube after a pollen grain has reached a compatible flower (pollen tube growth) are important aspects of plant developmental biology. In recent years, a wealth of information has been gathered about the molecular control of cell polarity, membrane trafficking and cytoskeletal dynamics underlying these developmental processes. In particular, it has been found that regulatory membrane phospholipids, such as phosphoinositides (PIs), are critical regulatory players, controlling key steps of trafficking and polarization. Characteristic features of PIs are the inositol phosphate headgroups of the lipids, which protrude from the cytosolic surfaces of membranes, enabling specific binding and recruitment of numerous protein partners containing specific PI-binding domains. Such recruitment is globally an early event in polarization processes of eukaryotic cells and also of key importance to pollen development and tube growth. Additionally, PIs serve as precursors of other signaling factors with importance to male gametogenesis. This review highlights the recent advances about the roles of PIs in pollen development and pollen function.
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Affiliation(s)
- Ingo Heilmann
- Department of Cellular Biochemistry, Institute for Biochemistry, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120, Halle (Saale), Germany.
| | - Till Ischebeck
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, Justus-von-Liebig-Weg 11, 37077, Göttingen, Germany.
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42
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Ganesan S, Shabits BN, Zaremberg V. Tracking Diacylglycerol and Phosphatidic Acid Pools in Budding Yeast. Lipid Insights 2016; 8:75-85. [PMID: 27081314 PMCID: PMC4824325 DOI: 10.4137/lpi.s31781] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 02/24/2016] [Accepted: 03/05/2016] [Indexed: 02/07/2023] Open
Abstract
Phosphatidic acid (PA) and diacylglycerol (DAG) are key signaling molecules and important precursors for the biosynthesis of all glycerolipids found in eukaryotes. Research conducted in the model organism Saccharomyces cerevisiae has been at the forefront of the identification of the enzymes involved in the metabolism and transport of PA and DAG. Both these lipids can alter the local physical properties of membranes by introducing negative curvature, but the anionic nature of the phosphomonoester headgroup in PA sets it apart from DAG. As a result, the mechanisms underlying PA and DAG interaction with other lipids and proteins are notoriously different. This is apparent from the analysis of the protein domains responsible for recognition and binding to each of these lipids. We review the current evidence obtained using the PA-binding proteins and domains fused to fluorescent proteins for in vivo tracking of PA pools in yeast. In addition, we present original results for visualization of DAG pools in yeast using the C1 domain from mammalian PKCδ. An emerging first cellular map of the distribution of PA and DAG pools in actively growing yeast is discussed.
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Affiliation(s)
| | - Brittney N Shabits
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Vanina Zaremberg
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
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Lum MA, Barger CJ, Hsu AH, Leontieva OV, Black AR, Black JD. Protein Kinase Cα (PKCα) Is Resistant to Long Term Desensitization/Down-regulation by Prolonged Diacylglycerol Stimulation. J Biol Chem 2016; 291:6331-46. [PMID: 26769967 DOI: 10.1074/jbc.m115.696211] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Indexed: 11/06/2022] Open
Abstract
Sustained activation of PKCα is required for long term physiological responses, such as growth arrest and differentiation. However, studies with pharmacological agonists (e.g. phorbol 12-myristate 13-acetate (PMA)) indicate that prolonged stimulation leads to PKCα desensitization via dephosphorylation and/or degradation. The current study analyzed effects of chronic stimulation with the physiological agonist diacylglycerol. Repeated addition of 1,2-dioctanoyl-sn-glycerol (DiC8) resulted in sustained plasma membrane association of PKCα in a pattern comparable with that induced by PMA. However, although PMA potently down-regulated PKCα, prolonged activation by DiC8 failed to engage known desensitization mechanisms, with the enzyme remaining membrane-associated and able to support sustained downstream signaling. DiC8-activated PKCα did not undergo dephosphorylation, ubiquitination, or internalization, early events in PKCα desensitization. Although DiC8 efficiently down-regulated novel PKCs PKCδ and PKCϵ, differences in Ca(2+) sensitivity and diacylglycerol affinity were excluded as mediators of the selective resistance of PKCα. Roles for Hsp/Hsc70 and Hsp90 were also excluded. PMA, but not DiC8, targeted PKCα to detergent-resistant membranes, and disruption of these domains with cholesterol-binding agents demonstrated a role for differential membrane compartmentalization in selective agonist-induced degradation. Chronic DiC8 treatment failed to desensitize PKCα in several cell types and did not affect PKCβI; thus, conventional PKCs appear generally insensitive to desensitization by sustained diacylglycerol stimulation. Consistent with this conclusion, prolonged (several-day) membrane association/activation of PKCα is seen in self-renewing epithelium of the intestine, cervix, and skin. PKCα deficiency affects gene expression, differentiation, and tumorigenesis in these tissues, highlighting the importance of mechanisms that protect PKCα from desensitization in vivo.
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Affiliation(s)
- Michelle A Lum
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950 and the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - Carter J Barger
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950 and
| | - Alice H Hsu
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950 and
| | - Olga V Leontieva
- the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - Adrian R Black
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950 and the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - Jennifer D Black
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950 and the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
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44
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Novel Features of DAG-Activated PKC Isozymes Reveal a Conserved 3-D Architecture. J Mol Biol 2016; 428:121-141. [DOI: 10.1016/j.jmb.2015.11.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 11/01/2015] [Indexed: 01/17/2023]
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45
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Murate M, Kobayashi T. Revisiting transbilayer distribution of lipids in the plasma membrane. Chem Phys Lipids 2016; 194:58-71. [DOI: 10.1016/j.chemphyslip.2015.08.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 08/14/2015] [Accepted: 08/17/2015] [Indexed: 12/22/2022]
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46
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Kohnhorst CL, Schmitt DL, Sundaram A, An S. Subcellular functions of proteins under fluorescence single-cell microscopy. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1864:77-84. [PMID: 26025769 PMCID: PMC5679394 DOI: 10.1016/j.bbapap.2015.05.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Revised: 05/08/2015] [Accepted: 05/18/2015] [Indexed: 11/25/2022]
Abstract
A cell is a highly organized, dynamic, and intricate biological entity orchestrated by a myriad of proteins and their self-assemblies. Because a protein's actions depend on its coordination in both space and time, our curiosity about protein functions has extended from the test tube into the intracellular space of the cell. Accordingly, modern technological developments and advances in enzymology have been geared towards analyzing protein functions within intact single cells. We discuss here how fluorescence single-cell microscopy has been employed to identify subcellular locations of proteins, detect reversible protein-protein interactions, and measure protein activity and kinetics in living cells. Considering that fluorescence single-cell microscopy has been only recently recognized as a primary technique in enzymology, its potentials and outcomes in studying intracellular protein functions are projected to be immensely useful and enlightening. We anticipate that this review would inspire many investigators to study their proteins of interest beyond the conventional boundary of specific disciplines. This article is part of a Special Issue entitled: Physiological Enzymology and Protein Functions.
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Affiliation(s)
- Casey L Kohnhorst
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250, USA
| | - Danielle L Schmitt
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250, USA
| | - Anand Sundaram
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250, USA
| | - Songon An
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250, USA.
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47
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Zamani A, Decker C, Cremasco V, Hughes L, Novack DV, Faccio R. Diacylglycerol Kinase ζ (DGKζ) Is a Critical Regulator of Bone Homeostasis Via Modulation of c-Fos Levels in Osteoclasts. J Bone Miner Res 2015; 30:1852-63. [PMID: 25891971 PMCID: PMC4580562 DOI: 10.1002/jbmr.2533] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 04/07/2015] [Accepted: 04/10/2015] [Indexed: 12/31/2022]
Abstract
Increased diacylglycerol (DAG) levels are observed in numerous pathologies, including conditions associated with bone loss. However, the effects of DAG accumulation on the skeleton have never been directly examined. Because DAG is strictly controlled by tissue-specific diacylglycerol kinases (DGKs), we sought to examine the biological consequences of DAG accumulation on bone homeostasis by genetic deletion of DGKζ, a highly expressed DGK isoform in osteoclasts (OCs). Strikingly, DGKζ(-/-) mice are osteoporotic because of a marked increase in OC numbers. In vitro, DGKζ(-/-) bone marrow macrophages (BMMs) form more numerous, larger, and highly resorptive OCs. Surprisingly, although increased DAG levels do not alter receptor activator of NF-κB (RANK)/RANK ligand (RANKL) osteoclastogenic pathway, DGKζ deficiency increases responsiveness to the proliferative and pro-survival cytokine macrophage colony-stimulating factor (M-CSF). We find that M-CSF is responsible for increased DGKζ(-/-) OC differentiation by promoting higher expression of the transcription factor c-Fos, and c-Fos knockdown in DGKζ(-/-) cultures dose-dependently reduces OC differentiation. Using a c-Fos luciferase reporter assay lacking the TRE responsive element, we also demonstrate that M-CSF induces optimal c-Fos expression through DAG production. Finally, to demonstrate the importance of the M-CSF/DGKζ/DAG axis on regulation of c-Fos during osteoclastogenesis, we turned to PLCγ2(+/-) BMMs, which have reduced DAG levels and form fewer OCs because of impaired expression of the master regulator of osteoclastogenesis NFATc1 and c-Fos. Strikingly, genetic deletion of DGKζ in PLCγ2(+/-) mice rescues OC formation and normalizes c-Fos levels without altering NFATc1 expression. To our knowledge, this is the first report implicating M-CSF/DGKζ/DAG axis as a critical regulator of bone homeostasis via its actions on OC differentiation and c-Fos expression.
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Affiliation(s)
- Ali Zamani
- Department of Orthopaedics; Washington University School of Medicine; St. Louis, MO, 63110; USA
| | - Corinne Decker
- Department of Orthopaedics; Washington University School of Medicine; St. Louis, MO, 63110; USA
| | - Viviana Cremasco
- Department of Orthopaedics; Washington University School of Medicine; St. Louis, MO, 63110; USA
| | - Lindsey Hughes
- Department of Orthopaedics; Washington University School of Medicine; St. Louis, MO, 63110; USA
| | - Deborah V. Novack
- Department of Pathology and Immunology; Washington University School of Medicine; St. Louis, MO, 63110; USA
| | - Roberta Faccio
- Department of Orthopaedics; Washington University School of Medicine; St. Louis, MO, 63110; USA
- Corresponding Author Roberta Faccio, Box 8233, 660 S. Euclid, St. Louis, MO 63110, USA, Phone: 314-747-4602, Fax: 314-362-0334,
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48
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Clostridium perfringens Alpha-Toxin Induces Gm1a Clustering and Trka Phosphorylation in the Host Cell Membrane. PLoS One 2015; 10:e0120497. [PMID: 25910247 PMCID: PMC4409118 DOI: 10.1371/journal.pone.0120497] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Accepted: 01/23/2015] [Indexed: 01/13/2023] Open
Abstract
Clostridium perfringens alpha-toxin elicits various immune responses such as the release of cytokines, chemokines, and superoxide via the GM1a/TrkA complex. Alpha-toxin possesses phospholipase C (PLC) hydrolytic activity that contributes to signal transduction in the pathogenesis of gas gangrene. Little is known about the relationship between lipid metabolism and TrkA activation by alpha-toxin. Using live-cell fluorescence microscopy, we monitored transbilayer movement of diacylglycerol (DAG) with the yellow fluorescent protein-tagged C1AB domain of protein kinase C-γ (EYFP-C1AB). DAG accumulated at the marginal region of the plasma membrane in alpha toxin-treated A549 cells, which also exhibited GM1a clustering and TrkA phosphorylation. Annexin V binding assays showed that alpha-toxin induced the exposure of phosphatidylserine on the outer leaflet of the plasma membrane. However, H148G, a variant toxin which binds cell membrane and has no enzymatic activity, did not induce DAG translocation, GM1a clustering, or TrkA phosphorylation. Alpha-toxin also specifically activated endogenous phospholipase Cγ-1 (PLCγ-1), a TrkA adaptor protein, via phosphorylation. U73122, an endogenous PLC inhibitor, and siRNA for PLCγ-1 inhibited the formation of DAG and release of IL-8. GM1a accumulation and TrkA phosphorylation in A549 cells treated with alpha-toxin were also inhibited by U73122. These results suggest that the flip-flop motion of hydrophobic lipids such as DAG leads to the accumulation of GM1a and TrkA. We conclude that the formation of DAG by alpha-toxin itself (first step) and activation of endogenous PLCγ-1 (second step) leads to alterations in membrane dynamics, followed by strong phosphorylation of TrkA.
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49
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Mesenchymal chemotaxis requires selective inactivation of myosin II at the leading edge via a noncanonical PLCγ/PKCα pathway. Dev Cell 2014; 31:747-60. [PMID: 25482883 DOI: 10.1016/j.devcel.2014.10.024] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 07/25/2014] [Accepted: 10/29/2014] [Indexed: 11/23/2022]
Abstract
Chemotaxis, migration toward soluble chemical cues, is critical for processes such as wound healing and immune surveillance and is exhibited by various cell types, from rapidly migrating leukocytes to slow-moving mesenchymal cells. To study mesenchymal chemotaxis, we observed cell migration in microfluidic chambers that generate stable gradients of platelet-derived growth factor (PDGF). Surprisingly, we found that pathways implicated in amoeboid chemotaxis, such as PI3K and mammalian target of rapamycin signaling, are dispensable for PDGF chemotaxis. Instead, we find that local inactivation of Myosin IIA, through a noncanonical Ser1/2 phosphorylation of the regulatory light chain, is essential. This site is phosphorylated by PKCα, which is activated by an intracellular gradient of diacylglycerol generated by PLCγ. Using a combination of live imaging and gradients of activators/inhibitors in the microfluidic chambers, we demonstrate that this signaling pathway and subsequent inhibition of Myosin II activity at the leading edge are required for mesenchymal chemotaxis.
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50
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Welf ES, Danuser G. Using fluctuation analysis to establish causal relations between cellular events without experimental perturbation. Biophys J 2014; 107:2492-8. [PMID: 25468328 DOI: 10.1016/j.bpj.2014.10.032] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 10/08/2014] [Accepted: 10/09/2014] [Indexed: 11/18/2022] Open
Abstract
Experimental perturbations are commonly used to establish causal relationships between the molecular components of a pathway and their cellular functions; however, this approach suffers inherent limitations. Especially in pathways with a significant level of nonlinearity and redundancy among components, such perturbations induce compensatory responses that obscure the actual function of the targeted component in the unperturbed pathway. A complementary approach uses constitutive fluctuations in component activities to identify the hierarchy of information flow through pathways. Here, we review the motivation for using perturbation-free approaches and highlight recent advances made in using perturbation-free fluctuation analysis as a means to establish causality among cellular events.
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Affiliation(s)
- Erik S Welf
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Gaudenz Danuser
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas.
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