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An Electrophysiological Approach to Measure Changes in the Membrane Surface Potential in Real Time. Biophys J 2019; 118:813-825. [PMID: 31409481 PMCID: PMC7036697 DOI: 10.1016/j.bpj.2019.06.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 06/21/2019] [Accepted: 06/26/2019] [Indexed: 02/07/2023] Open
Abstract
Biological membranes carry fixed charges at their surfaces. These arise primarily from phospholipid headgroups. In addition, membrane proteins contribute to the surface potential with their charged residues. Membrane lipids are asymmetrically distributed. Because of this asymmetry, the net-negative charge at the inner leaflet exceeds that at the outer leaflet. Changes in surface potential are predicted to give rise to apparent changes in membrane capacitance. Here, we show that it is possible to detect changes in surface potential by an electrophysiological approach; the analysis of cellular currents relies on assuming that the electrical properties of a cell are faithfully described by a three-element circuit (i.e., the minimal equivalent circuit) comprised of two resistors and one capacitor. However, to account for changes in surface potential, it is necessary to add a battery to this circuit connected in series with the capacitor. This extended circuit model predicts that the current response to a square-wave voltage pulse harbors information, which allows for separating the changes in surface potential from a true capacitance change. We interrogated our model by investigating changes in the capacitance induced by ligand binding to the serotonin transporter and to the glycine transporters (GlyT1 and GlyT2). The experimental observations were consistent with the predictions of the extended circuit. We conclude that ligand-induced changes in surface potential (reflecting the binding event) and in true membrane capacitance (reflecting the concomitant conformational change) can be detected in real time even in instances in which they occur simultaneously.
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Ansari SA, Pendurthi UR, Rao LVM. Role of Cell Surface Lipids and Thiol-Disulphide Exchange Pathways in Regulating the Encryption and Decryption of Tissue Factor. Thromb Haemost 2019; 119:860-870. [PMID: 30861549 DOI: 10.1055/s-0039-1681102] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Tissue factor (TF), a transmembrane glycoprotein, is the cellular receptor of the coagulation factors VII (FVII) and VIIa (FVIIa). The formation of TF-FVIIa complex triggers the initiation of the blood coagulation pathway. TF plays an essential role in haemostasis, but an aberrant expression of TF activity contributes to thrombotic disorders. In health, TF pro-coagulant activity on cells is controlled tightly to allow sufficient coagulant activity to achieve haemostasis but not to cause thrombosis. It is achieved largely by selective localization of TF in the body and encryption of TF at the cell surface. A vast majority of TF on resting cells exists in an encrypted state with minimal pro-coagulant activity but becomes pro-thrombotic following cell injury or activation. At present, the mechanisms that are responsible for TF encryption and activation (decryption) are not entirely clear, but recent studies provide important mechanistic insights into these processes. To date, externalization of phosphatidylserine to the outer leaflet and thiol-disulphide exchange pathways that either turn on and off the allosteric disulphide bond in TF are shown to play a major role in regulating TF pro-coagulant activity on cell surfaces. Recent studies showed that sphingomyelin, a major phospholipid in the outer leaflet of plasma membrane, plays a critical role in the encryption of TF in resting cells. The present review provides an overview of recent literature on the above-described mechanisms of TF encryption and decryption with a particular emphasis on our recent findings.
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Affiliation(s)
- Shabbir A Ansari
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, Texas, United States
| | - Usha R Pendurthi
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, Texas, United States
| | - L Vijaya Mohan Rao
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, Texas, United States
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Proteomic analysis of neutrophils in ANCA-associated vasculitis reveals a dysregulation in proteinase 3-associated proteins such as annexin-A1 involved in apoptotic cell clearance. Kidney Int 2019; 96:397-408. [PMID: 31142442 DOI: 10.1016/j.kint.2019.02.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 01/22/2019] [Accepted: 02/14/2019] [Indexed: 02/06/2023]
Abstract
Granulomatosis with polyangiitis (GPA) is an autoimmune vasculitis associated with anti-neutrophil-cytoplasmic antibodies (ANCA) against proteinase 3 leading to kidney damage. Neutrophils from those patients have increased expression of membrane proteinase 3 during apoptosis. Here we examined whether neutrophils from patients with GPA have dysregulated protein expressions associated with apoptosis. A global proteomic analysis was performed comparing neutrophils from patients with GPA, with healthy individuals under basal conditions and during apoptosis. At disease onset, the cytosolic proteome of neutrophils of patients with GPA before treatment was significantly different from healthy controls, and this dysregulation was more pronounced following ex vivo apoptosis. Proteins involved in cell death/survival were altered in neutrophils of patients with GPA. Several proteins identified were PR3-binding partners involved in the clearance of apoptotic cells, namely calreticulin, annexin-A1 and phospholipid scramblase 1. These proteins form a platform at the membrane of apoptotic neutrophils in patients with GPA but not healthy individuals and this was associated with the clinical presentation of GPA. Thus, our study shows that neutrophils from patients with GPA have an intrinsic dysregulation in proteins involved in apoptotic cell clearance, which could contribute to the unabated inflammation and autoimmunity in GPA. Hence, harnessing these dysregulated pathways could lead to novel biomarkers and targeted therapeutic opportunities to treat kidney disease.
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Phosphatidylserine is a marker for axonal debris engulfment but its exposure can be decoupled from degeneration. Cell Death Dis 2018; 9:1116. [PMID: 30389906 PMCID: PMC6214901 DOI: 10.1038/s41419-018-1155-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 09/25/2018] [Accepted: 10/08/2018] [Indexed: 02/08/2023]
Abstract
Apoptotic cells expose Phosphatidylserine (PS), that serves as an “eat me” signal for engulfing cells. Previous studies have shown that PS also marks degenerating axonsduring developmental pruning or in response to insults (Wallerian degeneration), but the pathways that control PS exposure on degenerating axons are largely unknown. Here, we used a series of in vitro assays to systematically explore the regulation of PS exposure during axonal degeneration. Our results show that PS exposure is regulated by the upstream activators of axonal pruning and Wallerian degeneration. However, our investigation of signaling further downstream revealed divergence between axon degeneration and PS exposure. Importantly, elevation of the axonal energetic status hindered PS exposure, while inhibition of mitochondrial activity caused PS exposure, without degeneration. Overall, our results suggest that the levels of PS on the outer axonal membrane can be dissociated from the degeneration process and that the axonal energetic status plays a key role in the regulation of PS exposure.
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55
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Veit M, Koyro KI, Ahrens B, Bleibaum F, Munz M, Rövekamp H, Andrä J, Schreiber R, Kunzelmann K, Sommer A, Bhakdi S, Reiss K. Anoctamin-6 regulates ADAM sheddase function. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2018; 1865:1598-1610. [PMID: 30327201 DOI: 10.1016/j.bbamcr.2018.08.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 08/17/2018] [Accepted: 08/20/2018] [Indexed: 02/07/2023]
Abstract
ADAM17, a prominent member of the "Disintegrin and Metalloproteinase" (ADAM) family, controls vital cellular functions through cleavage of transmembrane substrates including TGF-alpha, Amphiregulin (AREG) and TNF-Receptor 1 (TNFR1). We recently presented evidence that surface exposure of phosphatidylserine (PS) is pivotal for ADAM17 to exert sheddase activity. Anoctamin-6 (ANO6) has Ca2+-dependent phospholipid scramblase activity and it followed that the functions of ANO6 and ADAM17 might be linked. We report that overexpression of ANO6 in HEK293T cells led to increased Ca2+-mediated PS-exposure that was indeed accompanied by enhanced release of AREG and TGF-alpha. The effect was not observed when cells were treated with the PKC-dependent ADAM17 activator PMA. Transformation of cells with a constitutively active ANO6 mutant led to spontaneous PS-exposure and to the release of ADAM17-substrates in the absence of any stimuli. Inhibitor experiments indicated that ANO6-mediated enhancement of substrate cleavage simultaneously broadened the spectrum of participating metalloproteinases. In complementary experiments, siRNA-mediated downregulation of ANO6 was shown to decrease ionophore-mediated release of TNFR1 in human umbilical vein endothelial cells (HUVECs). We conclude that ANO6, by virtue of its scramblase activity, may play a role as an important regulator of the ADAM-network in the plasma membrane.
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Affiliation(s)
- Martin Veit
- Dept. of Dermatology, University of Kiel, 24105 Kiel, Germany
| | | | - Björn Ahrens
- Dept. of Dermatology, University of Kiel, 24105 Kiel, Germany
| | | | - Martin Munz
- Dept. of Dermatology, University of Kiel, 24105 Kiel, Germany
| | - Hagen Rövekamp
- Dept. of Dermatology, University of Kiel, 24105 Kiel, Germany
| | - Jörg Andrä
- Hamburg University of Applied Science, Ulmenliet 20, 21033 Hamburg, Germany
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
| | - Anselm Sommer
- Dept. of Dermatology, University of Kiel, 24105 Kiel, Germany
| | - Sucharit Bhakdi
- Dept. of Dermatology, University of Kiel, 24105 Kiel, Germany
| | - Karina Reiss
- Dept. of Dermatology, University of Kiel, 24105 Kiel, Germany.
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56
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Palanirajan SK, Gummadi SN. Rapid method for an enhanced recovery of biologically active human phospholipid scramblase1 from inclusion bodies. Anal Biochem 2018; 556:104-111. [DOI: 10.1016/j.ab.2018.06.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 06/28/2018] [Accepted: 06/28/2018] [Indexed: 01/05/2023]
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57
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Park SC, Kim IR, Kim JY, Lee Y, Kim EJ, Jung JH, Jung YJ, Jang MK, Lee JR. Molecular mechanism of Arabidopsis thaliana profilins as antifungal proteins. Biochim Biophys Acta Gen Subj 2018; 1862:2545-2554. [PMID: 30056100 DOI: 10.1016/j.bbagen.2018.07.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 07/18/2018] [Accepted: 07/24/2018] [Indexed: 12/23/2022]
Abstract
BACKGROUND It remains an open question whether plant phloem sap proteins are functionally involved in plant defense mechanisms. METHODS The antifungal effects of two profilin proteins from Arabidopsis thaliana, AtPFN1 and AtPFN2, were tested against 11 molds and 4 yeast fungal strains. Fluorescence profiling, biophysical, and biochemical analyses were employed to investigate their antifungal mechanism. RESULTS Recombinant AtPFN1 and AtPFN2 proteins, expressed in Escherichia coli, inhibited the cell growth of various pathogenic fungal strains at concentrations ranging from 10 to 160 μg/mL. The proteins showed significant intracellular accumulation and cell-binding affinity for fungal cells. Interestingly, the AtPFN proteins could penetrate the fungal cell wall and membrane and act as inhibitors of fungal growth via generation of cellular reactive oxygen species and mitochondrial superoxide. This triggered the AtPFN variant-induced cell apoptosis, resulting in morphological changes in the cells. CONCLUSION PFNs may play a critical role as antifungal proteins in the Arabidopsis defense system against fungal pathogen attacks. GENERAL SIGNIFICANCE The present study indicates that two profilin proteins, AtPFN1 and AtPFN2, can act as natural antimicrobial agents in the plant defense system.
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Affiliation(s)
- Seong-Cheol Park
- Department of Polymer Science and Engineering, Sunchon National University, Suncheon, Jeonnam 57922, Republic of Korea
| | - Il Ryong Kim
- National Institute of Ecology (NIE), Seocheon, Choongnam 33657, Republic of Korea; Division of Applied Life Science and PMBBRC, Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea
| | - Jin-Young Kim
- Department of Polymer Science and Engineering, Sunchon National University, Suncheon, Jeonnam 57922, Republic of Korea
| | - Yongjae Lee
- Department of Nutrition and Food Science, Texas A&M University, College Station, TX 77843, USA; Goseong Agricultural Development/Technology Center, Goseong-gun, Gyeongsangnam-do 52930, Republic of Korea
| | - Eun-Ji Kim
- Department of Polymer Science and Engineering, Sunchon National University, Suncheon, Jeonnam 57922, Republic of Korea
| | - Ji Hyun Jung
- Division of Applied Life Science and PMBBRC, Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea; Department of Nutrition and Food Science, Texas A&M University, College Station, TX 77843, USA
| | - Young Jun Jung
- National Institute of Ecology (NIE), Seocheon, Choongnam 33657, Republic of Korea
| | - Mi-Kyeong Jang
- Department of Polymer Science and Engineering, Sunchon National University, Suncheon, Jeonnam 57922, Republic of Korea.
| | - Jung Ro Lee
- National Institute of Ecology (NIE), Seocheon, Choongnam 33657, Republic of Korea.
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58
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Rajagopalan P, Patel K, Jain AP, Nanjappa V, Datta KK, Subbannayya T, Mangalaparthi KK, Kumari A, Manoharan M, Coral K, Murugan S, Nair B, Prasad TSK, Mathur PP, Gupta R, Gupta R, Khanna-Gupta A, Califano J, Sidransky D, Gowda H, Chatterjee A. Molecular alterations associated with chronic exposure to cigarette smoke and chewing tobacco in normal oral keratinocytes. Cancer Biol Ther 2018; 19:773-785. [PMID: 29723088 DOI: 10.1080/15384047.2018.1470724] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Tobacco usage is a known risk factor associated with development of oral cancer. It is mainly consumed in two different forms (smoking and chewing) that vary in their composition and methods of intake. Despite being the leading cause of oral cancer, molecular alterations induced by tobacco are poorly understood. We therefore sought to investigate the adverse effects of cigarette smoke/chewing tobacco exposure in oral keratinocytes (OKF6/TERT1). OKF6/TERT1 cells acquired oncogenic phenotype after treating with cigarette smoke/chewing tobacco for a period of 8 months. We employed whole exome sequencing (WES) and quantitative proteomics to investigate the molecular alterations in oral keratinocytes chronically exposed to smoke/ chewing tobacco. Exome sequencing revealed distinct mutational spectrum and copy number alterations in smoke/ chewing tobacco treated cells. We also observed differences in proteomic alterations. Proteins downstream of MAPK1 and EGFR were dysregulated in smoke and chewing tobacco exposed cells, respectively. This study can serve as a reference for fundamental damages on oral cells as a consequence of exposure to different forms of tobacco.
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Affiliation(s)
- Pavithra Rajagopalan
- a Institute of Bioinformatics, International Tech Park , Bangalor , India.,b School of Biotechnology , Kalinga Institute of Industrial Technology , Bhubaneswar , India
| | - Krishna Patel
- a Institute of Bioinformatics, International Tech Park , Bangalor , India.,c School of Biotechnology , Amrita Vishwa Vidyapeetham , Kollam , India
| | - Ankit P Jain
- a Institute of Bioinformatics, International Tech Park , Bangalor , India.,b School of Biotechnology , Kalinga Institute of Industrial Technology , Bhubaneswar , India
| | | | - Keshava K Datta
- a Institute of Bioinformatics, International Tech Park , Bangalor , India
| | | | - Kiran K Mangalaparthi
- a Institute of Bioinformatics, International Tech Park , Bangalor , India.,c School of Biotechnology , Amrita Vishwa Vidyapeetham , Kollam , India
| | | | | | | | | | - Bipin Nair
- c School of Biotechnology , Amrita Vishwa Vidyapeetham , Kollam , India
| | - T S Keshava Prasad
- a Institute of Bioinformatics, International Tech Park , Bangalor , India.,e NIMHANS-IOB Bioinformatics and Proteomics Laboratory , Neurobiology Research Centre, National Institute of Mental Health and Neurosciences , Bangalore , India.,f Center for Systems Biology and Molecular Medicine , Yenepoya , Mangalore , India
| | - Premendu P Mathur
- b School of Biotechnology , Kalinga Institute of Industrial Technology , Bhubaneswar , India.,g Dept. of Biochemistry & Molecular Biology , School of Life Sciences, Pondicherry University , Pondicherry , India
| | - Ravi Gupta
- d Medgenome Labs Pvt. Ltd. , Bangalore , India
| | - Rohit Gupta
- d Medgenome Labs Pvt. Ltd. , Bangalore , India
| | | | - Joseph Califano
- h Department of Surgery , UC San Diego, Moores Cancer Center , La Jolla , CA , USA
| | - David Sidransky
- i Department of Otolaryngology-Head and Neck Surgery , Johns Hopkins University School of Medicine , Baltimore , MD , USA
| | - Harsha Gowda
- a Institute of Bioinformatics, International Tech Park , Bangalor , India
| | - Aditi Chatterjee
- a Institute of Bioinformatics, International Tech Park , Bangalor , India
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Luévano-Martínez LA, Kowaltowski AJ. Topological characterization of the mitochondrial phospholipid scramblase 3. FEBS Lett 2017; 591:4056-4066. [DOI: 10.1002/1873-3468.12917] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 11/10/2017] [Accepted: 11/13/2017] [Indexed: 12/18/2022]
Affiliation(s)
- Luis Alberto Luévano-Martínez
- Departamento de Parasitologia; Instituto de Ciências Biomédicas; Universidade de São Paulo; Brazil
- Departamento de Bioquímica; Instituto de Química; Universidade de São Paulo; Brazil
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Dopazo J, Erten C. Graph-theoretical comparison of normal and tumor networks in identifying BRCA genes. BMC SYSTEMS BIOLOGY 2017; 11:110. [PMID: 29166896 PMCID: PMC5700672 DOI: 10.1186/s12918-017-0495-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 11/13/2017] [Indexed: 12/18/2022]
Abstract
BACKGROUND Identification of driver genes related to certain types of cancer is an important research topic. Several systems biology approaches have been suggested, in particular for the identification of breast cancer (BRCA) related genes. Such approaches usually rely on differential gene expression and/or mutational landscape data. In some cases interaction network data is also integrated to identify cancer-related modules computationally. RESULTS We provide a framework for the comparative graph-theoretical analysis of networks integrating the relevant gene expression, mutations, and potein-protein interaction network data. The comparisons involve a graph-theoretical analysis of normal and tumor network pairs across all instances of a given set of breast cancer samples. The network measures under consideration are based on appropriate formulations of various centrality measures: betweenness, clustering coefficients, degree centrality, random walk distances, graph-theoretical distances, and Jaccard index centrality. CONCLUSIONS Among all the studied centrality-based graph-theoretical properties, we show that a betweenness-based measure differentiates BRCA genes across all normal versus tumor network pairs, than the rest of the popular centrality-based measures. The AUROC and AUPR values of the gene lists ordered with respect to the measures under study as compared to NCBI BioSystems pathway and the COSMIC database of cancer genes are the largest with the betweenness-based differentiation, followed by the measure based on degree centrality. In order to test the robustness of the suggested measures in prioritizing cancer genes, we further tested the two most promising measures, those based on betweenness and degree centralities, on randomly rewired networks. We show that both measures are quite resilient to noise in the input interaction network. We also compared the same measures against a state-of-the-art alternative disease gene prioritization method, MUFFFINN. We show that both our graph-theoretical measures outperform MUFFINN prioritizations in terms of ROC and precions/recall analysis. Finally, we filter the ordered list of the best measure, the betweenness-based differentiation, via a maximum-weight independent set formulation and investigate the top 50 genes in regards to literature verification. We show that almost all genes in the list are verified by the breast cancer literature and three genes are presented as novel genes that may potentialy be BRCA-related but missing in literature.
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Affiliation(s)
- Joaquin Dopazo
- Clinical Bioinformatics Research Area, Fundación Progreso y Salud, Hospital Virgen del Rocío, Sevilla, Spain
| | - Cesim Erten
- Computer Engineering, Antalya Bilim University, Antalya, Turkey.
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Maintenance and regulation of asymmetric phospholipid distribution in human erythrocyte membranes: implications for erythrocyte functions. Curr Opin Hematol 2017; 24:167-172. [PMID: 28118222 DOI: 10.1097/moh.0000000000000326] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE OF REVIEW The article summarizes new insights into the molecular mechanisms for the maintenance and regulation of the asymmetric distribution of phospholipids in human erythrocyte membranes. We focus on phosphatidylserine, which is primarily found in the inner leaflet of the membrane lipid bilayer under low Ca conditions (<1 μmol/l) and is exposed to the outer leaflet under elevated Ca concentrations (>1 μmol/l), when cells become senescent. Clarification of the molecular basis of phosphatidylserine flipping and scrambling is important for addressing long-standing questions regarding phosphatidylserine functions. RECENT FINDINGS ATP11C, a P-IV ATPase, has been identified as a major flippase in analyses of patient erythrocytes with a 90% reduction in flippase activity. Phospholipid scramblase 1 (PLSCR1) has been defined as a Ca-activated scramblase that is completely suppressed by membrane cholesterol under low Ca concentrations. SUMMARY For survival, phosphatidylserine surface exposure is prevented by cholesterol-mediated suppression of PLSCR1 under low Ca concentrations, irrespective of flipping by ATP11C. In senescent erythrocytes, PLSCR1 is activated by elevated Ca, resulting in phosphatidylserine exposure, allowing macrophage phagocytosis. These recent molecular findings establish the importance of the maintenance and regulation of phosphatidylserine distribution for both the survival and death of human erythrocytes.
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Sivagnanam U, Palanirajan SK, Gummadi SN. The role of human phospholipid scramblases in apoptosis: An overview. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:2261-2271. [PMID: 28844836 DOI: 10.1016/j.bbamcr.2017.08.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 08/03/2017] [Accepted: 08/10/2017] [Indexed: 02/08/2023]
Abstract
Human phospholipid scramblases (hPLSCRs) are a family of four homologous single pass transmembrane proteins (hPLSCR1-4) initially identified as the proteins responsible for Ca2+ mediated bidirectional phospholipid translocation in plasma membrane. Though in-vitro assays had provided evidence, the role of hPLSCRs in phospholipid translocation is still debated. Recent reports revealed a new class of proteins, TMEM16 and Xkr8 to exhibit scramblase activity challenging the function of hPLSCRs. Apart from phospholipid scrambling, numerous reports have emphasized the multifunctional roles of hPLSCRs in key cellular processes including tumorigenesis, antiviral defense, protein and DNA interactions, transcriptional regulation and apoptosis. In this review, the role of hPLSCRs in mediating cell death through phosphatidylserine exposure, interaction with death receptors, cardiolipin exposure, heavy metal and radiation induced apoptosis and pathological apoptosis followed by their involvement in cancer cells are discussed. This review aims to connect the multifunctional characteristics of hPLSCRs to their decisive involvement in apoptotic pathways.
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Affiliation(s)
- Ulaganathan Sivagnanam
- Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600 036, India
| | - Santosh Kumar Palanirajan
- Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600 036, India
| | - Sathyanarayana N Gummadi
- Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600 036, India.
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Sommer A, Düppe M, Baumecker L, Kordowski F, Büch J, Chico JF, Fritsch J, Schütze S, Adam D, Sperrhacke M, Bhakdi S, Reiss K. Extracellular sphingomyelinase activity impairs TNF-α-induced endothelial cell death via ADAM17 activation and TNF receptor 1 shedding. Oncotarget 2017; 8:72584-72596. [PMID: 29069811 PMCID: PMC5641154 DOI: 10.18632/oncotarget.19983] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 07/11/2017] [Indexed: 12/21/2022] Open
Abstract
ADAM17, a prominent member of the “Disintegrin and Metalloproteinase” (ADAM) family, is an important regulator of endothelial cell proliferation and cell survival. The protease controls vital cellular functions through cleavage of growth factors, cytokines and their receptors including transforming growth factor-alpha (TGF-α), tumor necrosis factor-alpha (TNF-α) and TNF-α receptor 1 (TNFR1). TNF-α is the major inducer of endothelial cell death in cardiovascular diseases. The latter are also characterized by elevated plasma and tissue levels of extracellular sphingomyelinase (SMase). Whether the SMase affects ADAM activity and thus endothelial cell function has not been addressed to date. Here, we analyzed the effect of SMase on ADAM17-mediated shedding in COS7 cells and in human umbilical vein endothelial cells (HUVECs). Exposure to SMase significantly increased ADAM17-mediated release of alkaline-phosphatase (AP)-tagged TGF-α in COS7 cells and shedding of endogenously expressed TNFR1 in HUVECs. We previously presented evidence that surface exposure of phosphatidylserine (PS) is pivotal for ADAM17 to exert sheddase function. We found that SMase treatment led to PS externalization in both cell types. Transient non-apoptotic PS exposure is often mediated by Ca2+-dependent phospholipid scramblases. Accordingly, the Ca2+-chelator EGTA markedly reduced the breakdown of phospholipid asymmetry and shedding of TGF-α and TNFR1. Moreover, sheddase activity was significantly diminished in the presence of the competing PS-headgroup OPLS. SMase-stimulated TNFR1 shedding strikingly diminished TNF-α-induced signalling cascades and endothelial cell death. Taken together, our data suggest that SMase activity might act as protective factor for endothelial cells in cardiovascular diseases.
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Affiliation(s)
- Anselm Sommer
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany
| | - Marie Düppe
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany
| | - Lena Baumecker
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany
| | - Felix Kordowski
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany
| | - Joscha Büch
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany
| | | | - Jürgen Fritsch
- Institute of Immunology, University of Kiel, 24105 Kiel, Germany
| | - Stefan Schütze
- Institute of Immunology, University of Kiel, 24105 Kiel, Germany
| | - Dieter Adam
- Institute of Immunology, University of Kiel, 24105 Kiel, Germany
| | - Maria Sperrhacke
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany
| | - Sucharit Bhakdi
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany
| | - Karina Reiss
- Department of Dermatology, University of Kiel, 24105 Kiel, Germany
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Lemke G. Phosphatidylserine Is the Signal for TAM Receptors and Their Ligands. Trends Biochem Sci 2017; 42:738-748. [PMID: 28734578 DOI: 10.1016/j.tibs.2017.06.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Revised: 06/04/2017] [Accepted: 06/08/2017] [Indexed: 12/20/2022]
Abstract
Nature repeatedly repurposes, in that molecules that serve as metabolites, energy depots, or polymer subunits are at the same time used to deliver signals within and between cells. The preeminent example of this repurposing is ATP, which functions as a building block for nucleic acids, an energy source for enzymatic reactions, a phosphate donor to regulate intracellular signaling, and a neurotransmitter to control the activity of neurons. A series of recent studies now consolidates the view that phosphatidylserine (PtdSer), a common phospholipid constituent of membrane bilayers, is similarly repurposed for use as a signal between cells and that the ligands and receptors of the Tyro3/Axl/Mer (TAM) family of receptor tyrosine kinases (RTKs) are prominent transducers of this signal.
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Affiliation(s)
- Greg Lemke
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA; Immunobiology and Microbial Pathogenesis Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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Martin KR, Witko-Sarsat V. Proteinase 3: the odd one out that became an autoantigen. J Leukoc Biol 2017; 102:689-698. [PMID: 28546501 DOI: 10.1189/jlb.3mr0217-069r] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 04/07/2017] [Accepted: 04/16/2017] [Indexed: 01/09/2023] Open
Abstract
Neutrophils are critical in the defense against bacterial and fungal pathogens, and they also modulate the inflammatory process. The areas where neutrophils are studied have expanded from the restricted field of antibacterial defense to the modulation of inflammation and finally, to fine-tuning immune responses. As a result, recent studies have shown that neutrophils are implicated in several systemic autoimmune diseases, although exactly how neutrophils contribute to these diseases and the molecular mechanisms responsible are still under investigation. In a group of autoimmune vasculitides associated with anti-neutrophil cytoplasmic antibodies (AAVs), granulomatosis with polyangiitis (GPA) illustrates the concept that autoimmunity can develop against one specific neutrophil protein, namely, proteinase 3 (PR3), one of the four serine protease homologs contained within azurophilic granules. In this review, we will focus on recent molecular analyses combined with functional studies that provide clear evidence that the pathogenic properties of PR3 are not only a result of its enzymatic activity but also mediated by a particular structural element-the hydrophobic patch-which facilitates associations with various proteins and lipids and permits anchorage into the plasma membrane. Furthermore, these unique structural and functional characteristics of PR3 might be key contributors to the systemic inflammation and to the immune dysregulation observed in GPA.
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Affiliation(s)
- Katherine R Martin
- Institut National de la Santé et de la Recherche Médicale, U1016, Institut Cochin, Paris, France.,Centre National de la Recherche Scientifique-Unité Mixte de Recherche 8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France; and.,Center of Excellence, LabEx Inflamex, Paris, France
| | - Véronique Witko-Sarsat
- Institut National de la Santé et de la Recherche Médicale, U1016, Institut Cochin, Paris, France; .,Centre National de la Recherche Scientifique-Unité Mixte de Recherche 8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France; and.,Center of Excellence, LabEx Inflamex, Paris, France
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66
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Hidai C, Fujiwara Y, Kokubun S, Kitano H. EGF domain of coagulation factor IX is conducive to exposure of phosphatidylserine. Cell Biol Int 2017; 41:374-383. [PMID: 28150893 DOI: 10.1002/cbin.10733] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 01/20/2017] [Indexed: 11/10/2022]
Abstract
Lipid rafts are an initiation site for many different signals. Recently, we reported that an EGF domain in activated coagulation factor IX (EGF-F9) increases lipid raft formation and accelerates cell migration. However, the detailed mechanism is not well understood. This study aimed to evaluate the effects of EGF-F9 on the cell membrane. A431 cells (derived from human squamous cell carcinoma) were treated with recombinant EGF-F9. Cells were immunocytochemically stained with probes for lipid rafts or phosphatidylserine (PS). After 3 min of treatment with EGF-F9, cholera toxin subunit B (CTxB) binding domains emerged at the adhesive tips of filopodia. Subsequently, CTxB staining was observed on the filopodial shaft. Finally, large clusters of CTxB domains were observed at the edge of cell bodies. Markers for lipid rafts, such as caveolin-1 and a GPI anchored protein, co-localized with CTxB. Staining with annexin V and XII revealed that PS was exposed at the tips of filopodia, translocated on filopodial shafts, and co-localized with CTxB at the rafts. Immunocytochemistry showed that scramblase-1 protein was present at the filopodial tips. Our data indicates that EGF-F9 accelerates PS exposure around the filopodial adhesion complex and induces clustering of lipid rafts in the cell body. PS exposure is thought to occur on cells undergoing apoptosis. Further study of the function of the EGF-F9 motif in mediating signal transduction is necessary because it is shared by a number of proteins.
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Affiliation(s)
- Chiaki Hidai
- Division of Physiology, Department of Biomedical Sciences, Nihon University School of Medicine, 30-1 Oyaguchikami-cho, Itabashi-ku, Tokyo 173-8610, Japan
| | - Yusuke Fujiwara
- Division of Physiology, Department of Biomedical Sciences, Nihon University School of Medicine, 30-1 Oyaguchikami-cho, Itabashi-ku, Tokyo 173-8610, Japan
| | - Shinichiro Kokubun
- Division of Physiology, Department of Biomedical Sciences, Nihon University School of Medicine, 30-1 Oyaguchikami-cho, Itabashi-ku, Tokyo 173-8610, Japan
| | - Hisataka Kitano
- Division of Physiology, Department of Biomedical Sciences, Nihon University School of Medicine, 30-1 Oyaguchikami-cho, Itabashi-ku, Tokyo 173-8610, Japan.,Division of Oral Surgery, Department of Otorhinolaryngology Head and Neck Surgery, Nihon University School of Medicine, Tokyo, Japan
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67
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Han Y, Li A, Gao L, Wu W, Deng H, Hu W, Li N, Sun S, Zhang X, Zhao B, Liu B, Pang Q. Identification and characterization of a phospholipid scramblase encoded by planarian Dugesia japonica. Gene 2017; 602:43-49. [DOI: 10.1016/j.gene.2016.11.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 10/27/2016] [Accepted: 11/15/2016] [Indexed: 01/02/2023]
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68
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Tufail Y, Cook D, Fourgeaud L, Powers CJ, Merten K, Clark CL, Hoffman E, Ngo A, Sekiguchi KJ, O'Shea CC, Lemke G, Nimmerjahn A. Phosphatidylserine Exposure Controls Viral Innate Immune Responses by Microglia. Neuron 2017; 93:574-586.e8. [PMID: 28111081 DOI: 10.1016/j.neuron.2016.12.021] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 10/17/2016] [Accepted: 12/15/2016] [Indexed: 01/09/2023]
Abstract
Microglia are the intrinsic immune sentinels of the central nervous system. Their activation restricts tissue injury and pathogen spread, but in some settings, including viral infection, this response can contribute to cell death and disease. Identifying mechanisms that control microglial responses is therefore an important objective. Using replication-incompetent adenovirus 5 (Ad5)-based vectors as a model, we investigated the mechanisms through which microglia recognize and respond to viral uptake. Transgenic, immunohistochemical, molecular-genetic, and fluorescence imaging approaches revealed that phosphatidylserine (PtdSer) exposure on the outer leaflet of transduced cells triggers their engulfment by microglia through TAM receptor-dependent mechanisms. We show that inhibition of phospholipid scramblase 1 (PLSCR1) activity reduces intracellular calcium dysregulation, prevents PtdSer externalization, and enables months-long protection of vector-transduced, transgene-expressing cells from microglial phagocytosis. Our study identifies PLSCR1 as a potent target through which the innate immune response to viral vectors, and potentially other stimuli, may be controlled.
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Affiliation(s)
- Yusuf Tufail
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Daniela Cook
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Lawrence Fourgeaud
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Colin J Powers
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Katharina Merten
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Charles L Clark
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Elizabeth Hoffman
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Alexander Ngo
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Kohei J Sekiguchi
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Clodagh C O'Shea
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Greg Lemke
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA; Immunobiology and Microbial Pathogenesis Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Axel Nimmerjahn
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
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69
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Sivagnanam U, Narayana Murthy S, Gummadi SN. Identification and characterization of the novel nuclease activity of human phospholipid scramblase 1. BMC BIOCHEMISTRY 2016; 17:10. [PMID: 27206388 PMCID: PMC4875679 DOI: 10.1186/s12858-016-0067-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 05/17/2016] [Indexed: 01/05/2023]
Abstract
Background Human phospholipid scramblase 1 (hPLSCR1) was initially identified as a Ca2+ dependent phospholipid translocator involved in disrupting membrane asymmetry. Recent reports revealed that hPLSCR1 acts as a multifunctional signaling molecule rather than functioning as scramblase. hPLSCR1 is overexpressed in a variety of tumor cells and is known to interact with a number of protein molecules implying diverse functions. Results In this study, the nuclease activity of recombinant hPLSCR1 and its biochemical properties have been determined. Point mutations were generated to identify the critical region responsible for the nuclease activity. Recombinant hPLSCR1 exhibits Mg2+ dependent nuclease activity with an optimum pH and temperature of 8.5 and 37 °C respectively. Experiments with amino acid modifying reagents revealed that histidine, cysteine and arginine residues were crucial for its function. hPLSCR1 has five histidine residues and point mutations of histidine residues to alanine in hPLSCR1 resulted in 60 % loss in nuclease activity. Thus histidine residues could play a critical role in the nuclease activity of hPLSCR1. Conclusions This is the first report on the novel nuclease activity of the multi-functional hPLSCR1. hPLSCR1 shows a metal dependent nuclease activity which could play a role in key cellular processes that needs to be further investigated.
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Affiliation(s)
- Ulaganathan Sivagnanam
- From the Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600 036, India
| | - Shweta Narayana Murthy
- From the Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600 036, India
| | - Sathyanarayana N Gummadi
- From the Applied and Industrial Microbiology Laboratory, Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600 036, India.
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Sommer A, Kordowski F, Büch J, Maretzky T, Evers A, Andrä J, Düsterhöft S, Michalek M, Lorenzen I, Somasundaram P, Tholey A, Sönnichsen FD, Kunzelmann K, Heinbockel L, Nehls C, Gutsmann T, Grötzinger J, Bhakdi S, Reiss K. Phosphatidylserine exposure is required for ADAM17 sheddase function. Nat Commun 2016; 7:11523. [PMID: 27161080 PMCID: PMC4866515 DOI: 10.1038/ncomms11523] [Citation(s) in RCA: 122] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 04/05/2016] [Indexed: 02/07/2023] Open
Abstract
ADAM17, a prominent member of the 'Disintegrin and Metalloproteinase' (ADAM) family, controls vital cellular functions through cleavage of transmembrane substrates. Here we present evidence that surface exposure of phosphatidylserine (PS) is pivotal for ADAM17 to exert sheddase activity. PS exposure is tightly coupled to substrate shedding provoked by diverse ADAM17 activators. PS dependency is demonstrated in the following: (a) in Raji cells undergoing apoptosis; (b) in mutant PSA-3 cells with manipulatable PS content; and (c) in Scott syndrome lymphocytes genetically defunct in their capacity to externalize PS in response to intracellular Ca(2+) elevation. Soluble phosphorylserine but not phosphorylcholine inhibits substrate cleavage. The isolated membrane proximal domain (MPD) of ADAM17 binds to PS but not to phosphatidylcholine liposomes. A cationic PS-binding motif is identified in this domain, replacement of which abrogates liposome-binding and renders the protease incapable of cleaving its substrates in cells. We speculate that surface-exposed PS directs the protease to its targets where it then executes its shedding function.
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Affiliation(s)
- Anselm Sommer
- Department of Dermatology, University of Kiel, Schittenhelmstrasse 7, Kiel 24105, Germany
| | - Felix Kordowski
- Department of Dermatology, University of Kiel, Schittenhelmstrasse 7, Kiel 24105, Germany
| | - Joscha Büch
- Department of Dermatology, University of Kiel, Schittenhelmstrasse 7, Kiel 24105, Germany
| | - Thorsten Maretzky
- Arthritis and Tissue Degeneration Program, Hospital for Special Surgery at Weill Medical College of Cornell University, New York, New York 10021, USA
| | - Astrid Evers
- Arthritis and Tissue Degeneration Program, Hospital for Special Surgery at Weill Medical College of Cornell University, New York, New York 10021, USA
| | - Jörg Andrä
- Hamburg University of Applied Science, Ulmenliet 20, Hamburg 21033, Germany
| | - Stefan Düsterhöft
- Institute of Biochemistry, University of Kiel, Olshausenstrasse 40, Kiel 24098, Germany
| | - Matthias Michalek
- Institute of Biochemistry, University of Kiel, Olshausenstrasse 40, Kiel 24098, Germany
| | - Inken Lorenzen
- Institute of Biochemistry, University of Kiel, Olshausenstrasse 40, Kiel 24098, Germany
| | - Prasath Somasundaram
- Division of Systematic Proteome Research and Bioanalytics, Institute for Experimental Medicine, University of Kiel, Kiel 24105, Germany
| | - Andreas Tholey
- Division of Systematic Proteome Research and Bioanalytics, Institute for Experimental Medicine, University of Kiel, Kiel 24105, Germany
| | - Frank D Sönnichsen
- Otto Diels Institute for Organic Chemistry, University of Kiel, Kiel 24118, Germany
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, Universitätsstrasse 31, Regensburg 93053, Germany
| | - Lena Heinbockel
- Forschungszentrum Borstel, Leibniz-Zentrum für Medizin and Biowissenschaften, Borstel 23845, Germany
| | - Christian Nehls
- Forschungszentrum Borstel, Leibniz-Zentrum für Medizin and Biowissenschaften, Borstel 23845, Germany
| | - Thomas Gutsmann
- Forschungszentrum Borstel, Leibniz-Zentrum für Medizin and Biowissenschaften, Borstel 23845, Germany
| | - Joachim Grötzinger
- Institute of Biochemistry, University of Kiel, Olshausenstrasse 40, Kiel 24098, Germany
| | - Sucharit Bhakdi
- Department of Dermatology, University of Kiel, Schittenhelmstrasse 7, Kiel 24105, Germany
| | - Karina Reiss
- Department of Dermatology, University of Kiel, Schittenhelmstrasse 7, Kiel 24105, Germany
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71
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LeBarron J, London E. Effect of lipid composition and amino acid sequence upon transmembrane peptide-accelerated lipid transleaflet diffusion (flip-flop). BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1812-20. [PMID: 27131444 DOI: 10.1016/j.bbamem.2016.04.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 03/21/2016] [Accepted: 04/21/2016] [Indexed: 12/15/2022]
Abstract
We examined how hydrophobic peptide-accelerated transleaflet lipid movement (flip-flop) was affected by peptide sequence and vesicle composition and properties. A peptide with a completely hydrophobic sequence had little if any effect upon flip-flop. While peptides with a somewhat less hydrophobic sequence accelerated flip-flop, the half-time remained slow (hours) with substantial (0.5mol%) peptide in the membranes. It appears that peptide-accelerated lipid flip-flop involves a rare event that may reflect a rare state of the peptide or lipid bilayer. There was no simple relationship between peptide overall hydrophobicity and flip-flop. In addition, flip-flop was not closely linked to whether the peptides were in a transmembrane or non-transmembrane (interfacial) inserted state. Flip-flop was also not associated with peptide-induced pore formation. We found that peptide-accelerated flip-flop is initially faster in small (highly curved) unilamellar vesicles relative to that in large unilamellar vesicles. Peptide-accelerated flip-flop was also affected by lipid composition, being slowed in vesicles with thick bilayers or those containing 30% cholesterol. Interestingly, these factors also slow spontaneous lipid flip-flop in the absence of peptide. Combined with previous studies, the results are most consistent with acceleration of lipid flip-flop by peptide-induced thinning of bilayer width.
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Affiliation(s)
- Jamie LeBarron
- Dept. of Biochemistry and Cell Biology, Stony Brook, NY 11794-5215, United States
| | - Erwin London
- Dept. of Biochemistry and Cell Biology, Stony Brook, NY 11794-5215, United States
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Tsai WB, Long Y, Park JR, Chang JT, Liu H, Rodriguez-Canales J, Savaraj N, Feun LG, Davies MA, Wistuba II, Kuo MT. Gas6/Axl is the sensor of arginine-auxotrophic response in targeted chemotherapy with arginine-depleting agents. Oncogene 2016; 35:1632-42. [PMID: 26096933 PMCID: PMC4835044 DOI: 10.1038/onc.2015.237] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 05/06/2015] [Accepted: 05/26/2015] [Indexed: 02/08/2023]
Abstract
Many human malignancies lack de novo biosynthesis of arginine (Arg) as the key enzyme argininosuccinate synthetase 1 (ASS1) is silenced. These tumors acquire ectopic Arg for survival, and depleting this source by Arg-depleting recombinant enzyme ADI-PEG20 results in cell death. Mechanisms underlying Arg auxotrophy in these tumors and how they respond to Arg-auxotrophic stress are poorly understood. Here, we report that an immediate-early event of Arg-auxotrophic response involves reactive oxygen species-mediated secretion of Gas6, which interacts with its receptor Axl and activates the downstream Ras/PI3K/Akt growth signal leading to accumulation of c-Myc by protein stabilization. Arg-auxotrophic challenge also transcriptionally upregulates c-Myc expression, which provides a feedback mechanism to enhance Axl expression. c-Myc is a positive regulator of ASS1, but elevated ASS1 provides a feedback mechanism to suppress c-Myc and Axl. Our results revealed multiple inter-regulatory pathways in Arg-auxotrophic response, consisting of Axl, c-Myc and ASS1, which regulate Arg homeostasis and ADI-PEG20 sensitivity. These pathways provide potential targets for improving the efficacy of treating Arg-auxotrophic tumors using Arg-deprivation strategies.
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Affiliation(s)
- Wen-Bin Tsai
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Yan Long
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Jeong-Ran Park
- Department of Thoracic and Cardiovascular Surgery, Kangwon National University, Gangwon, Korea 200-701
| | - Jeffrey T. Chang
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Hui Liu
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Jaime Rodriguez-Canales
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Niramol Savaraj
- Sylvester Comprehensive Cancer Center, University of Miami, Miami, FL 33135
| | - Lynn G. Feun
- Sylvester Comprehensive Cancer Center, University of Miami, VA Medical Center, Miami, Fl. 33125
| | - Michael A. Davies
- Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Ignacio I Wistuba
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
| | - Macus Tien Kuo
- Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030
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Borné Y, Söderholm M, Barregard L, Fagerberg B, Persson M, Melander O, Thévenod F, Hedblad B, Engström G. Genome wide association study identifies two loci associated with cadmium in erythrocytes among never-smokers. Hum Mol Genet 2016; 25:2342-2348. [DOI: 10.1093/hmg/ddw083] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 03/09/2016] [Indexed: 12/15/2022] Open
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Li T, Aredo B, Zhang K, Zhong X, Pulido JS, Wang S, He YG, Huang X, Brekken RA, Ufret-Vincenty RL. Phosphatidylserine (PS) Is Exposed in Choroidal Neovascular Endothelium: PS-Targeting Antibodies Inhibit Choroidal Angiogenesis In Vivo and Ex Vivo. Invest Ophthalmol Vis Sci 2016; 56:7137-45. [PMID: 26529048 DOI: 10.1167/iovs.15-17302] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
PURPOSE Choroidal neovascularization (CNV) accounts for 90% of cases of severe vision loss in patients with advanced age-related macular degeneration. Identifying new therapeutic targets for CNV may lead to novel combination therapies to improve outcomes and reduce treatment burden. Our goal was to test whether phosphatidylserine (PS) becomes exposed in the outer membrane of choroidal neovascular endothelium, and whether this could provide a new therapeutic target for CNV. METHODS Choroidal neovascularization was induced in C57BL/6J mice using laser photocoagulation. Choroidal neovascularization lesions costained for exposed PS and for intercellular adhesion molecule 2 (or isolectin B4) were imaged in flat mounts and in cross sections. The laser CNV model and a choroidal sprouting assay were used to test the effect of PS-targeting antibodies on choroidal angiogenesis. Choroidal neovascularization lesion size was determined by intercellular adhesion molecule 2 (ICAM-2) staining of flat mounts. RESULTS We found that PS was exposed in CNV lesions and colocalized with vascular endothelial staining. Treatment with PS-targeting antibodies led to a 40% to 80% reduction in CNV lesion area when compared to treatment with a control antibody. The effect was the same as that seen using an equal dose of an anti-VEGF antibody. Results were confirmed using the choroid sprouting assay, an ex vivo model of choroidal angiogenesis. CONCLUSIONS We demonstrated that PS is exposed in choroidal neovascular endothelium. Furthermore, targeting this exposed PS with antibodies may be of therapeutic value in CNV.
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Affiliation(s)
- Tao Li
- Department of Ophthalmology University of Texas Southwestern Medical Center, Dallas, Texas, United States 2Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of Chi
| | - Bogale Aredo
- Department of Ophthalmology University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Kaiyan Zhang
- Department of Ophthalmology University of Texas Southwestern Medical Center, Dallas, Texas, United States 3Department of Ophthalmology, Hainan Provincial People's Hospital, Haikou, Hainan, People's Republic of China
| | - Xin Zhong
- Department of Ophthalmology University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Jose S Pulido
- Departments of Ophthalmology and Molecular Medicine, Mayo Clinic, Rochester, Minnesota, United States
| | - Shusheng Wang
- Departments of Cell and Molecular Biology and Ophthalmology, Tulane University, New Orleans, Louisiana, United States
| | - Yu-Guang He
- Department of Ophthalmology University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Xianming Huang
- Department of Pharmacology and the Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Rolf A Brekken
- Department of Pharmacology and the Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, Texas, United States 7Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, United
| | - Rafael L Ufret-Vincenty
- Department of Ophthalmology University of Texas Southwestern Medical Center, Dallas, Texas, United States
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Whitlock JM, Hartzell HC. A Pore Idea: the ion conduction pathway of TMEM16/ANO proteins is composed partly of lipid. Pflugers Arch 2016; 468:455-73. [PMID: 26739711 PMCID: PMC4751199 DOI: 10.1007/s00424-015-1777-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 12/14/2015] [Accepted: 12/16/2015] [Indexed: 01/04/2023]
Abstract
Since their first descriptions, ion channels have been conceived as proteinaceous conduits that facilitate the passage of ionic cargo between segregated environments. This concept is reinforced by crystallographic structures of cation channels depicting ion conductance pathways completely lined by protein. Although lipids are sometimes present in fenestrations near the pore or may be involved in channel gating, there is little or no evidence that lipids inhabit the ion conduction pathway. Indeed, the presence of lipid acyl chains in the conductance pathway would curse the design of the channel's aqueous pore. Here, we make a speculative proposal that anion channels in the TMEM16/ANO superfamily have ion conductance pathways composed partly of lipids. Our reasoning is based on the idea that TMEM16 ion channels evolved from a kind of lipid transporter that scrambles lipids between leaflets of the membrane bilayer and the modeled structural similarity between TMEM16 lipid scramblases and TMEM16 anion channels. This novel view of the TMEM16 pore offers explanation for the biophysical and pharmacological oddness of TMEM16A. We build upon the recent X-ray structure of nhTMEM16 and develop models of both TMEM16 ion channels and lipid scramblases to bolster our proposal. It is our hope that this model of the TMEM16 pore will foster innovative investigation into TMEM16 function.
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Affiliation(s)
- Jarred M Whitlock
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - H Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA.
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Natural products against hematological malignancies and identification of their targets. SCIENCE CHINA-LIFE SCIENCES 2015; 58:1191-201. [DOI: 10.1007/s11427-015-4922-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 08/16/2015] [Indexed: 01/14/2023]
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Oropesa Ávila M, Fernández Vega A, Garrido Maraver J, Villanueva Paz M, De Lavera I, De La Mata M, Cordero MD, Alcocer Gómez E, Delgado Pavón A, Álvarez Córdoba M, Cotán D, Sánchez-Alcázar JA. Emerging roles of apoptotic microtubules during the execution phase of apoptosis. Cytoskeleton (Hoboken) 2015; 72:435-46. [PMID: 26382917 DOI: 10.1002/cm.21254] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 09/01/2015] [Accepted: 09/09/2015] [Indexed: 12/14/2022]
Abstract
Apoptosis is a genetically programmed energy-dependent process of cell demise, characterized by specific morphological and biochemical events in which the activation of caspases has an essential role. During apoptosis the cytoskeleton participates actively in characteristic morphological rearrangements of the dying cell. This reorganisation has been assigned mainly to actinomyosin ring contraction, while microtubule and intermediate filaments are depolymerized at early stages of apoptosis. However, recent reports have showed that microtubules are reformed during the execution phase of apoptosis organizing an apoptotic microtubule network (AMN). AMN is organized behind plasma membrane, forming a cortical structure. Apoptotic microtubules repolymerization takes place in many cell types and under different apoptotic inducers. It has been hypothesized that AMN is critical for maintaining plasma membrane integrity and cell morphology during the execution phase of apoptosis. AMN disorganization leads apoptotic cells to secondary necrosis and the release of potential toxic molecules which can damage neighbor cells and promotes inflammation. Therefore, AMN formation during physiological apoptosis or in pathological apoptosis induced by anti-cancer treatments is essential for tissue homeostasis and the prevention of additional cell damage and inflammation.
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Affiliation(s)
- Manuel Oropesa Ávila
- Centro Andaluz De Biología Del Desarrollo (CABD), and Centro De Investigación Biomédica En Red: Enfermedades Raras, Instituto De Salud Carlos III, Universidad Pablo De Olavide-Consejo Superior De Investigaciones Científicas, Sevilla, 41013, Spain
| | - Alejandro Fernández Vega
- Centro Andaluz De Biología Del Desarrollo (CABD), and Centro De Investigación Biomédica En Red: Enfermedades Raras, Instituto De Salud Carlos III, Universidad Pablo De Olavide-Consejo Superior De Investigaciones Científicas, Sevilla, 41013, Spain
| | - Juan Garrido Maraver
- Centro Andaluz De Biología Del Desarrollo (CABD), and Centro De Investigación Biomédica En Red: Enfermedades Raras, Instituto De Salud Carlos III, Universidad Pablo De Olavide-Consejo Superior De Investigaciones Científicas, Sevilla, 41013, Spain
| | - Marina Villanueva Paz
- Centro Andaluz De Biología Del Desarrollo (CABD), and Centro De Investigación Biomédica En Red: Enfermedades Raras, Instituto De Salud Carlos III, Universidad Pablo De Olavide-Consejo Superior De Investigaciones Científicas, Sevilla, 41013, Spain
| | - Isabel De Lavera
- Centro Andaluz De Biología Del Desarrollo (CABD), and Centro De Investigación Biomédica En Red: Enfermedades Raras, Instituto De Salud Carlos III, Universidad Pablo De Olavide-Consejo Superior De Investigaciones Científicas, Sevilla, 41013, Spain
| | - Mario De La Mata
- Centro Andaluz De Biología Del Desarrollo (CABD), and Centro De Investigación Biomédica En Red: Enfermedades Raras, Instituto De Salud Carlos III, Universidad Pablo De Olavide-Consejo Superior De Investigaciones Científicas, Sevilla, 41013, Spain
| | - Mario D Cordero
- Facultad De Odontología. Universidad De Sevilla, Sevilla, 41009, Spain
| | - Elizabet Alcocer Gómez
- Centro Andaluz De Biología Del Desarrollo (CABD), and Centro De Investigación Biomédica En Red: Enfermedades Raras, Instituto De Salud Carlos III, Universidad Pablo De Olavide-Consejo Superior De Investigaciones Científicas, Sevilla, 41013, Spain
| | - Ana Delgado Pavón
- Centro Andaluz De Biología Del Desarrollo (CABD), and Centro De Investigación Biomédica En Red: Enfermedades Raras, Instituto De Salud Carlos III, Universidad Pablo De Olavide-Consejo Superior De Investigaciones Científicas, Sevilla, 41013, Spain
| | - Mónica Álvarez Córdoba
- Centro Andaluz De Biología Del Desarrollo (CABD), and Centro De Investigación Biomédica En Red: Enfermedades Raras, Instituto De Salud Carlos III, Universidad Pablo De Olavide-Consejo Superior De Investigaciones Científicas, Sevilla, 41013, Spain
| | - David Cotán
- Centro Andaluz De Biología Del Desarrollo (CABD), and Centro De Investigación Biomédica En Red: Enfermedades Raras, Instituto De Salud Carlos III, Universidad Pablo De Olavide-Consejo Superior De Investigaciones Científicas, Sevilla, 41013, Spain
| | - José Antonio Sánchez-Alcázar
- Centro Andaluz De Biología Del Desarrollo (CABD), and Centro De Investigación Biomédica En Red: Enfermedades Raras, Instituto De Salud Carlos III, Universidad Pablo De Olavide-Consejo Superior De Investigaciones Científicas, Sevilla, 41013, Spain
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Miranda AM, Oliveira TG. Lipids under stress - a lipidomic approach for the study of mood disorders. Bioessays 2015; 37:1226-35. [DOI: 10.1002/bies.201500070] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- André Miguel Miranda
- Life and Health Sciences Research Institute (ICVS); School of Health Sciences; University of Minho; Campus Gualtar Braga Portugal
- ICVS/3B's - PT Government Associate Laboratory; Braga/Guimarães Portugal
| | - Tiago Gil Oliveira
- Life and Health Sciences Research Institute (ICVS); School of Health Sciences; University of Minho; Campus Gualtar Braga Portugal
- ICVS/3B's - PT Government Associate Laboratory; Braga/Guimarães Portugal
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Perez C, Gerber S, Boilevin J, Bucher M, Darbre T, Aebi M, Reymond JL, Locher KP. Structure and mechanism of an active lipid-linked oligosaccharide flippase. Nature 2015; 524:433-8. [PMID: 26266984 DOI: 10.1038/nature14953] [Citation(s) in RCA: 164] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 07/15/2015] [Indexed: 02/06/2023]
Abstract
The flipping of membrane-embedded lipids containing large, polar head groups is slow and energetically unfavourable, and is therefore catalysed by flippases, the mechanisms of which are unknown. A prominent example of a flipping reaction is the translocation of lipid-linked oligosaccharides that serve as donors in N-linked protein glycosylation. In Campylobacter jejuni, this process is catalysed by the ABC transporter PglK. Here we present a mechanism of PglK-catalysed lipid-linked oligosaccharide flipping based on crystal structures in distinct states, a newly devised in vitro flipping assay, and in vivo studies. PglK can adopt inward- and outward-facing conformations in vitro, but only outward-facing states are required for flipping. While the pyrophosphate-oligosaccharide head group of lipid-linked oligosaccharides enters the translocation cavity and interacts with positively charged side chains, the lipidic polyprenyl tail binds and activates the transporter but remains exposed to the lipid bilayer during the reaction. The proposed mechanism is distinct from the classical alternating-access model applied to other transporters.
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Affiliation(s)
- Camilo Perez
- Institute of Molecular Biology and Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Sabina Gerber
- Institute of Molecular Biology and Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Jérémy Boilevin
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Monika Bucher
- Institute of Molecular Biology and Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Tamis Darbre
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Markus Aebi
- Institute of Microbiology, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Jean-Louis Reymond
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland
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