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Croucher KM, Fleming SM. ATP13A2 (PARK9) and basal ganglia function. Front Neurol 2024; 14:1252400. [PMID: 38249738 PMCID: PMC10796451 DOI: 10.3389/fneur.2023.1252400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 12/11/2023] [Indexed: 01/23/2024] Open
Abstract
ATP13A2 is a lysosomal protein involved in polyamine transport with loss of function mutations associated with multiple neurodegenerative conditions. These include early onset Parkinson's disease, Kufor-Rakeb Syndrome, neuronal ceroid lipofuscinosis, hereditary spastic paraplegia, and amyotrophic lateral sclerosis. While ATP13A2 mutations may result in clinical heterogeneity, the basal ganglia appear to be impacted in the majority of cases. The basal ganglia is particularly vulnerable to environmental exposures such as heavy metals, pesticides, and industrial agents which are also established risk factors for many neurodegenerative conditions. Not surprisingly then, impaired function of ATP13A2 has been linked to heavy metal toxicity including manganese, iron, and zinc. This review discusses the role of ATP13A2 in basal ganglia function and dysfunction, potential common pathological mechanisms in ATP13A2-related disorders, and how gene x environment interactions may contribute to basal ganglia dysfunction.
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Affiliation(s)
- Kristina M. Croucher
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, OH, United States
- Biomedical Sciences Graduate Program, Kent State University, Kent, OH, United States
| | - Sheila M. Fleming
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, OH, United States
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2
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De Tito S, Turacchio G, Valente C. Negative Staining Electron Microscopy for Morpho-Functional Characterization of Purified Golgi Membranes from Mammalian Cells. Methods Mol Biol 2022; 2557:225-234. [PMID: 36512218 DOI: 10.1007/978-1-0716-2639-9_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The Golgi apparatus is a highly dynamic organelle that controls lipid and protein sorting in the endocytic and exocytic cellular pathways. Perturbation of the lipid homeostasis or of the molecular machineries that regulate membrane remodeling/trafficking events on the Golgi membranes can dramatically change the morphology and functions of the Golgi apparatus. So far, several approaches have been described to characterize and define the Golgi morphology in intact cells and in vitro. Here, we describe the application of negative staining (NS) electron microscopy (EM) on purified Golgi membranes from HeLa cells. This approach allows to quantify and functionally characterize membrane remodeling events upon specific treatments that alter the Golgi morphology.
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Affiliation(s)
- Stefano De Tito
- Institute of Experimental Endocrinology and Oncology, National Research Council, Naples, Italy.,Molecular Cell Biology of Autophagy, The Francis Crick Institute, London, UK
| | - Gabriele Turacchio
- Institute of Experimental Endocrinology and Oncology, National Research Council, Naples, Italy
| | - Carmen Valente
- Institute of Experimental Endocrinology and Oncology, National Research Council, Naples, Italy.
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3
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Wakana Y, Tagaya M. CARTS Formation Assay. Methods Mol Biol 2022; 2557:573-581. [PMID: 36512238 DOI: 10.1007/978-1-0716-2639-9_34] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Sorting and transport of secretory and membrane proteins occur at the trans-Golgi network (TGN). Carriers of the TGN to the cell surface (CARTS) are one of the carriers that mediate the transport of certain proteins from the TGN to the plasma membrane. Recent studies have shown that CARTS formation is dependent on membrane contact sites between the Golgi apparatus and the endoplasmic reticulum (ER). Here, we describe a method to visualize by fluorescence microscopy the formation of CARTS at the TGN. This method combines a reverse dimerization system for synchronized export from the ER of a CARTS-specific cargo, pancreatic adenocarcinoma upregulated factor, together with the halt of export from the TGN by a 20 °C block. Incubation of cells at 37 °C releases the 20 °C block and allows to monitor the formation of CARTS at the TGN. Finally, we also present a workflow to quantify CARTS formation using ImageJ software.
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Affiliation(s)
- Yuichi Wakana
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan.
| | - Mitsuo Tagaya
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan
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4
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Cui L, Li H, Xi Y, Hu Q, Liu H, Fan J, Xiang Y, Zhang X, Shui W, Lai Y. Vesicle trafficking and vesicle fusion: mechanisms, biological functions, and their implications for potential disease therapy. MOLECULAR BIOMEDICINE 2022; 3:29. [PMID: 36129576 PMCID: PMC9492833 DOI: 10.1186/s43556-022-00090-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 07/12/2022] [Indexed: 11/10/2022] Open
Abstract
Intracellular vesicle trafficking is the fundamental process to maintain the homeostasis of membrane-enclosed organelles in eukaryotic cells. These organelles transport cargo from the donor membrane to the target membrane through the cargo containing vesicles. Vesicle trafficking pathway includes vesicle formation from the donor membrane, vesicle transport, and vesicle fusion with the target membrane. Coat protein mediated vesicle formation is a delicate membrane budding process for cargo molecules selection and package into vesicle carriers. Vesicle transport is a dynamic and specific process for the cargo containing vesicles translocation from the donor membrane to the target membrane. This process requires a group of conserved proteins such as Rab GTPases, motor adaptors, and motor proteins to ensure vesicle transport along cytoskeletal track. Soluble N-ethyl-maleimide-sensitive factor (NSF) attachment protein receptors (SNARE)-mediated vesicle fusion is the final process for vesicle unloading the cargo molecules at the target membrane. To ensure vesicle fusion occurring at a defined position and time pattern in eukaryotic cell, multiple fusogenic proteins, such as synaptotagmin (Syt), complexin (Cpx), Munc13, Munc18 and other tethering factors, cooperate together to precisely regulate the process of vesicle fusion. Dysfunctions of the fusogenic proteins in SNARE-mediated vesicle fusion are closely related to many diseases. Recent studies have suggested that stimulated membrane fusion can be manipulated pharmacologically via disruption the interface between the SNARE complex and Ca2+ sensor protein. Here, we summarize recent insights into the molecular mechanisms of vesicle trafficking, and implications for the development of new therapeutics based on the manipulation of vesicle fusion.
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Kwak JH, Kim S, Pak HK, Sung SK, Kwak J, Lee SW, Kim CH, Kim GR. Preparation of Giant Quantum Dot-Liposome Complexes by the Asolectin Lipid and Theoretical Model for Stabilization of Nanoparticle Inside the Liposome. J BIOMATER TISS ENG 2022. [DOI: 10.1166/jbt.2022.3087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We prepare giant Quantum dot-Liposome Complexes (QLCs). Quantum dots (QDs) incorporated inside liposome above 10 μm. QLCs is made by using the electro-swelling method combined with spin coating techniques. Three types of PC lipids and asolectin lipid are used for QLCs with
HDA (hexadecylamine) coated QDs, which ranged from blue- (diameter ~2.1 nm) to red-emission (diameter ~5.0 nm). As expected, (blue- or) green-emission QDs (smaller than) comparable to the thickness of PC lipid bilayer (~4 nm) are successfully formed QLCs, but QDs bigger than that fail to reproduce.
This observation is well-consistent with those reported by Gopakumar et al. Surprisingly, all QDs irrespective of their size are, contrary to PC lipids, successfully loaded into asolectin lipid bilayer. In order to understand what makes different behaviors between PC and asolectin lipids on
QLC formation, we suggest a theoretical model based on a geometrical assumptions for deformed lipid bilayer surrounding QD. The main advantage of this model is that the critical size Rcr of QD radius can be decided without calculating elastic free energy. As a result, it
predicts that only QDs below the critical size (diameter ~3.0 nm) can be loaded in a typical PC-lipid, but all size of QDs can be incorporated into asolectin bilayer under the assumption of two different curvatures on deformed monolayer.
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Affiliation(s)
- Jong Hyeok Kwak
- Department of Radiology, Pusan National University Yang-san Hospital, Yangsan, 50612, Korea
| | - Sungho Kim
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - Hyuk Kyu Pak
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - Soon Ki Sung
- Department of Neurosurgery, Pusan National University Yang-san Hospital, Yangsan, 50612, Korea
| | - Jinsung Kwak
- Department of Physics, Changwon National University, Changwon, 51140, Korea
| | - Sang Weon Lee
- Department of Neurosurgery, Pusan National University Yang-san Hospital, Yangsan, 50612, Korea
| | - Chang Hyeun Kim
- Department of Neurosurgery, Pusan National University Yang-san Hospital, Yangsan, 50612, Korea
| | - Gyeong Rip Kim
- Department of Neurosurgery, Pusan National University Yang-san Hospital, Yangsan, 50612, Korea
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Jebastin K, Narayanasamy D. Rationale utilization of phospholipid excipients: a distinctive tool for progressing state of the art in research of emerging drug carriers. J Liposome Res 2022; 33:1-33. [PMID: 35543241 DOI: 10.1080/08982104.2022.2069809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Phospholipids have a high degree of biocompatibility and are deemed ideal pharmaceutical excipients in the development of lipid-based drug delivery systems, because of their unique features (permeation, solubility enhancer, emulsion stabilizer, micelle forming agent, and the key excipients in solid dispersions) they can be used in a variety of pharmaceutical drug delivery systems, such as liposomes, phytosomes, solid lipid nanoparticles, etc. The primary usage of phospholipids in a colloidal pharmaceutical formulation is to enhance the drug's bioavailability with low aqueous solubility [i.e. Biopharmaceutical Classification System (BCS) Class II drugs], Membrane penetration (i.e. BCS Class III drugs), drug uptake and release enhancement or modification, protection of sensitive active pharmaceutical ingredients (APIs) from gastrointestinal degradation, a decrease of gastrointestinal adverse effects, and even masking of the bitter taste of orally delivered drugs are other uses. Phospholipid-based colloidal drug products can be tailored to address a wide variety of product requirements, including administration methods, cost, product stability, toxicity, and efficacy. Such formulations that are also a cost-effective method for developing medications for topical, oral, pulmonary, or parenteral administration. The originality of this review work is that we comprehensively evaluated the unique properties and special aspects of phospholipids and summarized how the individual phospholipids can be utilized in various types of lipid-based drug delivery systems, as well as listing newly marketed lipid-based products, patents, and continuing clinical trials of phospholipid-based therapeutic products. This review would be helpful for researchers responsible for formulation development and research into novel colloidal phospholipid-based drug delivery systems.
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Affiliation(s)
- Koilpillai Jebastin
- Department of Pharmaceutics, SRM College of Pharmacy, SRM Institute of Science and Technology, Kattankulathur, India
| | - Damodharan Narayanasamy
- Department of Pharmaceutics, SRM College of Pharmacy, SRM Institute of Science and Technology, Kattankulathur, India
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Yamazaki Y, Eura Y, Kokame K. V-ATPase V0a1 promotes Weibel-Palade body biogenesis through the regulation of membrane fission. eLife 2021; 10:71526. [PMID: 34904569 PMCID: PMC8718113 DOI: 10.7554/elife.71526] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 12/13/2021] [Indexed: 01/09/2023] Open
Abstract
Membrane fission, the division of a membrane-bound structure into two discrete compartments, is essential for diverse cellular events, such as endocytosis and vesicle/granule biogenesis; however, the process remains unclear. The hemostatic protein von Willebrand factor is produced in vascular endothelial cells and packaged into specialized secretory granules, Weibel–Palade bodies (WPBs) at the trans-Golgi network (TGN). Here, we reported that V0a1, a V-ATPase component, is required for the membrane fission of WPBs. We identified two V0a isoforms in distinct populations of WPBs in cultured endothelial cells, V0a1 and V0a2, on mature and nascent WPBs, respectively. Although WPB buds were formed, WPBs could not separate from the TGN in the absence of V0a1. Screening using dominant–negative forms of known membrane fission regulators revealed protein kinase D (PKD) as an essential factor in biogenesis of WPBs. Further, we showed that the induction of wild-type PKDs in V0a1-depleted cells does not support the segregation of WPBs from the TGN; suggesting a primary role of V0a1 in the membrane fission of WPBs. The identification of V0a1 as a new membrane fission regulator should facilitate the understanding of molecular events that enable membrane fission.
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Affiliation(s)
- Yasuo Yamazaki
- Department of Molecular Pathogenesis, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Yuka Eura
- Department of Molecular Pathogenesis, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Koichi Kokame
- Department of Molecular Pathogenesis, National Cerebral and Cardiovascular Center, Osaka, Japan
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8
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The PKD-Dependent Biogenesis of TGN-to-Plasma Membrane Transport Carriers. Cells 2021; 10:cells10071618. [PMID: 34203456 PMCID: PMC8303525 DOI: 10.3390/cells10071618] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/14/2021] [Accepted: 06/24/2021] [Indexed: 01/30/2023] Open
Abstract
Membrane trafficking is essential for processing and transport of proteins and lipids and to establish cell compartmentation and tissue organization. Cells respond to their needs and control the quantity and quality of protein secretion accordingly. In this review, we focus on a particular membrane trafficking route from the trans-Golgi network (TGN) to the cell surface: protein kinase D (PKD)-dependent pathway for constitutive secretion mediated by carriers of the TGN to the cell surface (CARTS). Recent findings highlight the importance of lipid signaling by organelle membrane contact sites (MCSs) in this pathway. Finally, we discuss our current understanding of multiple signaling pathways for membrane trafficking regulation mediated by PKD, G protein-coupled receptors (GPCRs), growth factors, metabolites, and mechanosensors.
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Abstract
Phosphatidate phosphatase (PAP) catalyzes the penultimate step in the synthesis of triacylglycerol and regulates the synthesis of membrane phospholipids. There is much interest in this enzyme because it controls the cellular levels of its substrate, phosphatidate (PA), and product, DAG; defects in the metabolism of these lipid intermediates are the basis for lipid-based diseases such as obesity, lipodystrophy, and inflammation. The measurement of PAP activity is required for studies aimed at understanding its mechanisms of action, how it is regulated, and for screening its activators and/or inhibitors. Enzyme activity is determined through the use of radioactive and nonradioactive assays that measure the product, DAG, or Pi However, sensitivity and ease of use are variable across these methods. This review summarizes approaches to synthesize radioactive PA, to analyze radioactive and nonradioactive products, DAG and Pi, and discusses the advantages and disadvantages of each PAP assay.
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Affiliation(s)
- Prabuddha Dey
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ, USA
| | - Gil-Soo Han
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ, USA
| | - George M Carman
- Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, NJ, USA.
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10
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Testing Pollen Tube Proteins for In Vivo Binding to Phosphatidic Acid by n-Butanol Treatment and Confocal Microscopy. Methods Mol Biol 2020. [PMID: 32529446 DOI: 10.1007/978-1-0716-0672-8_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The general role of cellular membranes is to provide a barrier and to generate separate reaction spaces. However, additional functions of membrane domains enriched in certain classes of lipids have been discovered, which represent an important area of ongoing research. Such membrane domains can be found in cells at different size scales (e.g., nanodomains, microdomains), represent membrane regions with special physical properties and play important roles in the direct or indirect propagation of signaling processes. Domain formation within the plasma membrane (PM) does not only involve the accumulation of specific lipids, but also the recruitment of specific transmembrane or PM-associated peripheral proteins. Phosphatidic acid (PA) is increasingly recognized as an important signaling lipid and component of PM domains. This lipid is involved in the regulation not only of biotic or abiotic stress responses, but also of pollen tube tip growth and of other forms of polar cell expansion. Although many PA-binding proteins have been characterized, a conserved PA interaction motif could not be identified in these proteins. Consequently, protein binding to PA cannot be predicted based on sequence analysis, but has to be biochemically tested using lipid strip or liposome assays. Although these assays are often informative, they are generally based on the use of artificial model membranes, which compared to natural membranes contain fewer lipid types often at non-physiological concentrations. In this chapter, we describe an alternative in vivo assay that can be employed to analyze protein binding to PA at the PM of normally elongating tobacco pollen tubes. This assay is based on the use of n-butanol (n-ButOH), which inhibits phospholipase D (PLD) and thereby blocks a major biosynthetic pathway that generates PA within the PM from substrates like phosphatidylcholine (PC) or phosphatidylethanolamine (PE). PLD inhibition reduces the PA content of the PM and consequently the level of PM association of PA-binding proteins, which can be analyzed using fluorescence microscopy. Methods enabling n-ButOH treatment of cultured tobacco pollen tubes expressing YFP-tagged PA-binding proteins as well as the quantitative determination of the PM association of these proteins are described.
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11
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Stalder D, Gershlick DC. Direct trafficking pathways from the Golgi apparatus to the plasma membrane. Semin Cell Dev Biol 2020; 107:112-125. [PMID: 32317144 PMCID: PMC7152905 DOI: 10.1016/j.semcdb.2020.04.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 04/03/2020] [Accepted: 04/06/2020] [Indexed: 12/19/2022]
Abstract
In eukaryotic cells, protein sorting is a highly regulated mechanism important for many physiological events. After synthesis in the endoplasmic reticulum and trafficking to the Golgi apparatus, proteins sort to many different cellular destinations including the endolysosomal system and the extracellular space. Secreted proteins need to be delivered directly to the cell surface. Sorting of secreted proteins from the Golgi apparatus has been a topic of interest for over thirty years, yet there is still no clear understanding of the machinery that forms the post-Golgi carriers. Most evidence points to these post-Golgi carriers being tubular pleomorphic structures that bud from the trans-face of the Golgi. In this review, we present the background studies and highlight the key components of this pathway, we then discuss the machinery implicated in the formation of these carriers, their translocation across the cytosol, and their fusion at the plasma membrane.
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Key Words
- ATP, adenosine triphosphate
- BFA, Brefeldin A
- CARTS, CARriers of the TGN to the cell Surface
- CI-MPR, cation-independent mannose-6 phosphate receptor
- Constitutive Secretion
- CtBP3/BARS, C-terminus binding protein 3/BFA adenosine diphosphate–ribosylated substrate
- ER, endoplasmic reticulum
- GPI-anchored proteins, glycosylphosphatidylinositol-anchored proteins
- GlcCer, glucosylceramidetol
- Golgi to plasma membrane sorting
- PAUF, pancreatic adenocarcinoma up-regulated factor
- PKD, Protein Kinase D
- RUSH, retention using selective hooks
- SBP, streptavidin-binding peptide
- SM, sphingomyelin
- SNARE, soluble N-ethylmaleimide sensitive fusion protein attachment protein receptor
- SPCA1, secretory pathway calcium ATPase 1
- Secretion
- TGN, trans-Golgi Network
- TIRF, total internal reflection fluorescence
- VSV, vesicular stomatitis virus
- pleomorphic tubular carriers
- post-Golgi carriers
- ts, temperature sensitive
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Affiliation(s)
- Danièle Stalder
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - David C Gershlick
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom.
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Zhukovsky MA, Filograna A, Luini A, Corda D, Valente C. Protein Amphipathic Helix Insertion: A Mechanism to Induce Membrane Fission. Front Cell Dev Biol 2019; 7:291. [PMID: 31921835 PMCID: PMC6914677 DOI: 10.3389/fcell.2019.00291] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 11/06/2019] [Indexed: 12/19/2022] Open
Abstract
One of the fundamental features of biomembranes is the ability to fuse or to separate. These processes called respectively membrane fusion and fission are central in the homeostasis of events such as those related to intracellular membrane traffic. Proteins that contain amphipathic helices (AHs) were suggested to mediate membrane fission via shallow insertion of these helices into the lipid bilayer. Here we analyze the AH-containing proteins that have been identified as essential for membrane fission and categorize them in few subfamilies, including small GTPases, Atg proteins, and proteins containing either the ENTH/ANTH- or the BAR-domain. AH-containing fission-inducing proteins may require cofactors such as additional proteins (e.g., lipid-modifying enzymes), or lipids (e.g., phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2], phosphatidic acid [PA], or cardiolipin). Both PA and cardiolipin possess a cone shape and a negative charge (-2) that favor the recruitment of the AHs of fission-inducing proteins. Instead, PtdIns(4,5)P2 is characterized by an high negative charge able to recruit basic residues of the AHs of fission-inducing proteins. Here we propose that the AHs of fission-inducing proteins contain sequence motifs that bind lipid cofactors; accordingly (K/R/H)(K/R/H)xx(K/R/H) is a PtdIns(4,5)P2-binding motif, (K/R)x6(F/Y) is a cardiolipin-binding motif, whereas KxK is a PA-binding motif. Following our analysis, we show that the AHs of many fission-inducing proteins possess five properties: (a) at least three basic residues on the hydrophilic side, (b) ability to oligomerize, (c) optimal (shallow) depth of insertion into the membrane, (d) positive cooperativity in membrane curvature generation, and (e) specific interaction with one of the lipids mentioned above. These lipid cofactors favor correct conformation, oligomeric state and optimal insertion depth. The most abundant lipid in a given organelle possessing high negative charge (more negative than -1) is usually the lipid cofactor in the fission event. Interestingly, naturally occurring mutations have been reported in AH-containing fission-inducing proteins and related to diseases such as centronuclear myopathy (amphiphysin 2), Charcot-Marie-Tooth disease (GDAP1), Parkinson's disease (α-synuclein). These findings add to the interest of the membrane fission process whose complete understanding will be instrumental for the elucidation of the pathogenesis of diseases involving mutations in the protein AHs.
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Affiliation(s)
- Mikhail A. Zhukovsky
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | | | | | - Daniela Corda
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Carmen Valente
- Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
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Zhukovsky MA, Filograna A, Luini A, Corda D, Valente C. Phosphatidic acid in membrane rearrangements. FEBS Lett 2019; 593:2428-2451. [PMID: 31365767 DOI: 10.1002/1873-3468.13563] [Citation(s) in RCA: 99] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 07/25/2019] [Accepted: 07/26/2019] [Indexed: 12/16/2022]
Abstract
Phosphatidic acid (PA) is the simplest cellular glycerophospholipid characterized by unique biophysical properties: a small headgroup; negative charge; and a phosphomonoester group. Upon interaction with lysine or arginine, PA charge increases from -1 to -2 and this change stabilizes protein-lipid interactions. The biochemical properties of PA also allow interactions with lipids in several subcellular compartments. Based on this feature, PA is involved in the regulation and amplification of many cellular signalling pathways and functions, as well as in membrane rearrangements. Thereby, PA can influence membrane fusion and fission through four main mechanisms: it is a substrate for enzymes producing lipids (lysophosphatidic acid and diacylglycerol) that are involved in fission or fusion; it contributes to membrane rearrangements by generating negative membrane curvature; it interacts with proteins required for membrane fusion and fission; and it activates enzymes whose products are involved in membrane rearrangements. Here, we discuss the biophysical properties of PA in the context of the above four roles of PA in membrane fusion and fission.
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Affiliation(s)
- Mikhail A Zhukovsky
- Institute of Protein Biochemistry and Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Angela Filograna
- Institute of Protein Biochemistry and Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Alberto Luini
- Institute of Protein Biochemistry and Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Daniela Corda
- Institute of Protein Biochemistry and Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
| | - Carmen Valente
- Institute of Protein Biochemistry and Institute of Biochemistry and Cell Biology, National Research Council, Naples, Italy
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14
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Zhukovsky MA, Filograna A, Luini A, Corda D, Valente C. The Structure and Function of Acylglycerophosphate Acyltransferase 4/ Lysophosphatidic Acid Acyltransferase Delta (AGPAT4/LPAATδ). Front Cell Dev Biol 2019; 7:147. [PMID: 31428612 PMCID: PMC6688108 DOI: 10.3389/fcell.2019.00147] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 07/16/2019] [Indexed: 12/27/2022] Open
Abstract
Lipid-modifying enzymes serve crucial roles in cellular processes such as signal transduction (producing lipid-derived second messengers), intracellular membrane transport (facilitating membrane remodeling needed for membrane fusion/fission), and protein clustering (organizing lipid domains as anchoring platforms). The lipid products crucial in these processes can derive from different metabolic pathways, thus it is essential to know the localization, substrate specificity, deriving products (and their function) of all lipid-modifying enzymes. Here we discuss an emerging family of these enzymes, the lysophosphatidic acid acyltransferases (LPAATs), also known as acylglycerophosphate acyltransferases (AGPATs), that produce phosphatidic acid (PA) having as substrates lysophosphatidic acid (LPA) and acyl-CoA. Eleven LPAAT/AGPAT enzymes have been identified in mice and humans based on sequence homologies, and their localization, specific substrates and functions explored. We focus on one member of the family, LPAATδ, a protein expressed mainly in brain and in muscle (though to a lesser extent in other tissues); while at the cellular level it is localized at the trans-Golgi network membranes and at the mitochondrial outer membranes. LPAATδ is a physiologically essential enzyme since mice knocked-out for Lpaatδ show severe dysfunctions including cognitive impairment, impaired force contractility and altered white adipose tissue. The LPAATδ physiological roles are related to the formation of its product PA. PA is a multifunctional lipid involved in cell signaling as well as in membrane remodeling. In particular, the LPAATδ-catalyzed conversion of LPA (inverted-cone-shaped lipid) to PA (cone-shaped lipid) is considered a mechanism of deformation of the bilayer that favors membrane fission. Indeed, LPAATδ is an essential component of the fission-inducing machinery driven by the protein BARS. In this process, a protein-tripartite complex (BARS/14-3-3γ/phosphoinositide kinase PI4KIIIβ) is recruited at the trans-Golgi network, at the sites where membrane fission is to occur; there, LPAATδ directly interacts with BARS and is activated by BARS. The resulting formation of PA is essential for membrane fission occurring at those spots. Also in mitochondria PA formation has been related to fusion/fission events. Since PA is formed by various enzymatic pathways in different cell compartments, the BARS-LPAATδ interaction indicates the relevance of lipid-modifying enzymes acting exactly where their products are needed (i.e., PA at the Golgi membranes).
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Affiliation(s)
- Mikhail A Zhukovsky
- Institute of Biochemistry and Cell Biology and Institute of Protein Biochemistry, National Research Council, Naples, Italy
| | - Angela Filograna
- Institute of Biochemistry and Cell Biology and Institute of Protein Biochemistry, National Research Council, Naples, Italy
| | - Alberto Luini
- Institute of Biochemistry and Cell Biology and Institute of Protein Biochemistry, National Research Council, Naples, Italy
| | - Daniela Corda
- Institute of Biochemistry and Cell Biology and Institute of Protein Biochemistry, National Research Council, Naples, Italy
| | - Carmen Valente
- Institute of Biochemistry and Cell Biology and Institute of Protein Biochemistry, National Research Council, Naples, Italy
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15
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Hennessy M, Granade ME, Hassaninasab A, Wang D, Kwiatek JM, Han GS, Harris TE, Carman GM. Casein kinase II-mediated phosphorylation of lipin 1β phosphatidate phosphatase at Ser-285 and Ser-287 regulates its interaction with 14-3-3β protein. J Biol Chem 2019; 294:2365-2374. [PMID: 30617183 DOI: 10.1074/jbc.ra118.007246] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 01/04/2019] [Indexed: 12/20/2022] Open
Abstract
The mammalian lipin 1 phosphatidate phosphatase is a key regulatory enzyme in lipid metabolism. By catalyzing phosphatidate dephosphorylation, which produces diacylglycerol, the enzyme plays a major role in the synthesis of triacylglycerol and membrane phospholipids. The importance of lipin 1 to lipid metabolism is exemplified by cellular defects and lipid-based diseases associated with its loss or overexpression. Phosphorylation of lipin 1 governs whether it is associated with the cytoplasm apart from its substrate or with the endoplasmic reticulum membrane where its enzyme reaction occurs. Lipin 1β is phosphorylated on multiple sites, but less than 10% of them are ascribed to a specific protein kinase. Here, we demonstrate that lipin 1β is a bona fide substrate for casein kinase II (CKII), a protein kinase that is essential to viability and cell cycle progression. Phosphoamino acid analysis and phosphopeptide mapping revealed that lipin 1β is phosphorylated by CKII on multiple serine and threonine residues, with the former being major sites. Mutational analysis of lipin 1β and its peptides indicated that Ser-285 and Ser-287 are both phosphorylated by CKII. Substitutions of Ser-285 and Ser-287 with nonphosphorylatable alanine attenuated the interaction of lipin 1β with 14-3-3β protein, a regulatory hub that facilitates the cytoplasmic localization of phosphorylated lipin 1. These findings advance our understanding of how phosphorylation of lipin 1β phosphatidate phosphatase regulates its interaction with 14-3-3β protein and intracellular localization and uncover a mechanism by which CKII regulates cellular physiology.
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Affiliation(s)
- Meagan Hennessy
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901 and
| | - Mitchell E Granade
- the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Azam Hassaninasab
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901 and
| | - Dana Wang
- the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Joanna M Kwiatek
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901 and
| | - Gil-Soo Han
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901 and
| | - Thurl E Harris
- the Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - George M Carman
- From the Department of Food Science and the Rutgers Center for Lipid Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901 and
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16
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Yang F, Chen GX. Production of extracellular lysophosphatidic acid in the regulation of adipocyte functions and liver fibrosis. World J Gastroenterol 2018; 24:4132-4151. [PMID: 30271079 PMCID: PMC6158478 DOI: 10.3748/wjg.v24.i36.4132] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 04/24/2018] [Accepted: 05/05/2018] [Indexed: 02/06/2023] Open
Abstract
Lysophosphatidic acid (LPA), a glycerophospholipid, consists of a glycerol backbone connected to a phosphate head group and an acyl chain linked to sn-1 or sn-2 position. In the circulation, LPA is in sub-millimolar range and mainly derived from hydrolysis of lysophosphatidylcholine, a process mediated by lysophospholipase D activity in proteins such as autotaxin (ATX). Intracellular and extracellular LPAs act as bioactive lipid mediators with diverse functions in almost every mammalian cell type. The binding of LPA to its receptors LPA1-6 activates multiple cellular processes such as migration, proliferation and survival. The production of LPA and activation of LPA receptor signaling pathways in the events of physiology and pathophysiology have attracted the interest of researchers. Results from studies using transgenic and gene knockout animals with alterations of ATX and LPA receptors genes, have revealed the roles of LPA signaling pathways in metabolic active tissues and organs. The present review was aimed to summarize recent progresses in the studies of extracellular and intracellular LPA production pathways. This includes the functional, structural and biochemical properties of ATX and LPA receptors. The potential roles of LPA production and LPA receptor signaling pathways in obesity, insulin resistance and liver fibrosis are also discussed.
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Affiliation(s)
- Fang Yang
- School of Laboratory Medicine, Hubei University of Chinese Medicine, Wuhan 430065, Hubei Province, China
| | - Guo-Xun Chen
- Department of Nutrition, University of Tennessee at Knoxville, Knoxville, TN 37996, United States
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17
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Dirr ER, Ekhator OR, Blackwood R, Holden JG, Masliah E, Schultheis PJ, Fleming SM. Exacerbation of sensorimotor dysfunction in mice deficient in Atp13a2 and overexpressing human wildtype alpha-synuclein. Behav Brain Res 2018; 343:41-49. [PMID: 29407413 PMCID: PMC5829010 DOI: 10.1016/j.bbr.2018.01.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 01/17/2018] [Accepted: 01/22/2018] [Indexed: 12/26/2022]
Abstract
Loss of function mutations in the gene ATP13A2 are associated with Kufor-Rakeb Syndrome and Neuronal Ceroid Lipofuscinosis, the former designated as an inherited form of Parkinson's disease (PD). The function of ATP13A2 is unclear but in vitro studies indicate it is a lysosomal protein and may interact with the presynaptic protein alpha-synuclein (aSyn) and certain heavy metals. Accumulation of aSyn is a major component of lewy bodies, the pathological hallmark of PD. Atp13a2-deficient (13a2) mice develop age-dependent sensorimotor deficits, and accumulation of insoluble aSyn in the brain. To better understand the interaction between ATP13A2 and aSyn, double mutant mice with loss of Atp13a2 function combined with overexpression of human wildtype aSyn were generated. Female and male wildtype (WT), 13a2, aSyn, and 13a2-aSyn mice were tested on a battery of sensorimotor tests including adhesive removal, challenging beam traversal, spontaneous activity, gait, locomotor activity, and nest-building at 2, 4, and 6 months of age. Double mutant mice showed an earlier onset and accelerated alterations in sensorimotor function that were age, sex and test-dependent. Female 13a2-aSyn mice showed early and progressive dysfunction on the beam and in locomotor activity. In males, 13a2-aSyn mice showed more severe impairments in spontaneous activity and adhesive removal. Sex differences were also observed in aSyn and 13a2-aSyn mice on the beam, cylinder, and adhesive removal tests. In other tasks, double mutant mice displayed deficits similar to aSyn mice. These results indicate loss of Atp13a2 function exacerbates the sensorimotor phenotype in aSyn mice in an age and sex-dependent manner.
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Affiliation(s)
- Emily R Dirr
- Department of Neurology, School of Medicine, University of Cincinnati, USA
| | - Osunde R Ekhator
- Department of Neurology, School of Medicine, University of Cincinnati, USA
| | - Rachel Blackwood
- Department of Neurology, School of Medicine, University of Cincinnati, USA
| | - John G Holden
- Department of Neurology, School of Medicine, University of Cincinnati, USA
| | | | | | - Sheila M Fleming
- Department of Pharmaceutical Sciences and Center for Neurodegenerative Disease and Aging, Northeast Ohio Medical University, USA.
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18
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Abstract
Glucose and Glutamine are two essential ingredients for cell growth. However, it remains open for investigation whether there is a general mechanism that coordinates the consumption of glucose and glutamine in cancer cells. Glutamine is mainly metabolized through the glutaminolysis pathway and our previous report indicated that CtBP increases GDH activity and promotes glutaminolysis through repressing the expression of SIRT4, a well-known mitochondrion-located factor that inhibits glutaminolysis pathway. CtBP is known to be a sensor of intracellular metabolic status; we thus hypothesized that a consensus CtBP-SIRT4-GDH axis may mediate the crosstalk between glycolysis and glutaminolysis. Herein, supporting this hypothesis, we observed the coordinated consumption of glucose and glutamine across different cell lines. This coordination was found to be related to CtBP repression activity on SIRT4 expression under high level of glucose but not low glucose level. Low level of glucose supply was found to decrease GDH activity via blocking CtBP dimerization. Mechanically, low glucose also abolished CtBP binding to SIRT4 promoter and the repression of SIRT4 expression. Consistently, the CtBP dimerization inhibitor MTOB mimicked low glucose effects on SIRT4 expression, and GDH activity suggest that CtBP requires high glucose supply to act as a suppressor of SIRT4 gene. In conclusion, we propose that a general molecular pathway composed by CtBP-SIRT4-GDH coordinating the metabolism of glucose and glutamine in cancer cells.
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19
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Different Golgi ultrastructure across species and tissues: Implications under functional and pathological conditions, and an attempt at classification. Tissue Cell 2017; 49:186-201. [DOI: 10.1016/j.tice.2016.12.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Revised: 12/05/2016] [Accepted: 12/05/2016] [Indexed: 02/08/2023]
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Pagliuso A, Valente C, Giordano LL, Filograna A, Li G, Circolo D, Turacchio G, Marzullo VM, Mandrich L, Zhukovsky MA, Formiggini F, Polishchuk RS, Corda D, Luini A. Golgi membrane fission requires the CtBP1-S/BARS-induced activation of lysophosphatidic acid acyltransferase δ. Nat Commun 2016; 7:12148. [PMID: 27401954 PMCID: PMC4945875 DOI: 10.1038/ncomms12148] [Citation(s) in RCA: 214] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 06/03/2016] [Indexed: 11/25/2022] Open
Abstract
Membrane fission is an essential cellular process by which continuous membranes split into separate parts. We have previously identified CtBP1-S/BARS (BARS) as a key component of a protein complex that is required for fission of several endomembranes, including basolateral post-Golgi transport carriers. Assembly of this complex occurs at the Golgi apparatus, where BARS binds to the phosphoinositide kinase PI4KIIIβ through a 14-3-3γ dimer, as well as to ARF and the PKD and PAK kinases. We now report that, when incorporated into this complex, BARS binds to and activates a trans-Golgi lysophosphatidic acid (LPA) acyltransferase type δ (LPAATδ) that converts LPA into phosphatidic acid (PA); and that this reaction is essential for fission of the carriers. LPA and PA have unique biophysical properties, and their interconversion might facilitate the fission process either directly or indirectly (via recruitment of proteins that bind to PA, including BARS itself).
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Affiliation(s)
- Alessandro Pagliuso
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, Pozzuoli 80078, Italy
| | - Carmen Valente
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Lucia Laura Giordano
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Angela Filograna
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Guiling Li
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Diego Circolo
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Gabriele Turacchio
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Vincenzo Manuel Marzullo
- IRCCS SDN Istituto di Ricerca Diagnostica e Nucleare, Via Emanuele Gianturco 113, 80143 Naples, Italy
| | - Luigi Mandrich
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Mikhail A. Zhukovsky
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Fabio Formiggini
- Italian Institute of Technology, Centre for Advanced Biomaterials for Health Care at CRIB, Largo Barsanti e Matteucci 53, Naples 80125, Italy
| | - Roman S. Polishchuk
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, Pozzuoli 80078, Italy
| | - Daniela Corda
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Alberto Luini
- Institute of Protein Biochemistry, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
- IRCCS SDN Istituto di Ricerca Diagnostica e Nucleare, Via Emanuele Gianturco 113, 80143 Naples, Italy
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21
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Vodicka P, Mo S, Tousley A, Green KM, Sapp E, Iuliano M, Sadri-Vakili G, Shaffer SA, Aronin N, DiFiglia M, Kegel-Gleason KB. Mass Spectrometry Analysis of Wild-Type and Knock-in Q140/Q140 Huntington's Disease Mouse Brains Reveals Changes in Glycerophospholipids Including Alterations in Phosphatidic Acid and Lyso-Phosphatidic Acid. J Huntingtons Dis 2016; 4:187-201. [PMID: 26397899 DOI: 10.3233/jhd-150149] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Huntington's disease (HD) is a neurodegenerative disease caused by a CAG expansion in the HD gene, which encodes the protein Huntingtin. Huntingtin associates with membranes and can interact directly with glycerophospholipids in membranes. OBJECTIVE We analyzed glycerophospholipid profiles from brains of 11 month old wild-type (WT) and Q140/Q140 HD knock-in mice to assess potential changes in glycerophospholipid metabolism. METHODS Polar lipids from cerebellum, cortex, and striatum were extracted and analyzed by liquid chromatography and negative ion electrospray tandem mass spectrometry analysis (LC-MS/MS). Gene products involved in polar lipid metabolism were studied using western blotting, immuno-electron microscopy and qPCR. RESULTS Significant changes in numerous species of glycerophosphate (phosphatidic acid, PA) were found in striatum, cerebellum and cortex from Q140/Q140 HD mice compared to WT mice at 11 months. Changes in specific species could also be detected for other glycerophospholipids. Increases in species of lyso-PA (LPA) were measured in striatum of Q140/Q140 HD mice compared to WT. Protein levels for c-terminal binding protein 1 (CtBP1), a regulator of PA biosynthesis, were reduced in striatal synaptosomes from HD mice compared to wild-type at 6 and 12 months. Immunoreactivity for CtBP1 was detected on membranes of synaptic vesicles in striatal axon terminals in the globus pallidus. CONCLUSIONS These novel results identify a potential site of molecular pathology caused by mutant Huntingtin that may impart early changes in HD.
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Affiliation(s)
- Petr Vodicka
- Department of Neurology, Massachusetts General Hospital, Charlestown, MA, USA
| | - Shunyan Mo
- Proteomics and Mass Spectrometry Facility and Department of Biochemistry and Molecular Pharmacology, UMASS Medical School, Worcester, MA, USA
| | - Adelaide Tousley
- Department of Neurology, Massachusetts General Hospital, Charlestown, MA, USA
| | - Karin M Green
- Proteomics and Mass Spectrometry Facility and Department of Biochemistry and Molecular Pharmacology, UMASS Medical School, Worcester, MA, USA
| | - Ellen Sapp
- Department of Neurology, Massachusetts General Hospital, Charlestown, MA, USA
| | - Maria Iuliano
- Department of Neurology, Massachusetts General Hospital, Charlestown, MA, USA
| | | | - Scott A Shaffer
- Proteomics and Mass Spectrometry Facility and Department of Biochemistry and Molecular Pharmacology, UMASS Medical School, Worcester, MA, USA
| | - Neil Aronin
- Departments of Medicine and Cell and Developmental Biology, UMASS Medical School, Worcester, MA, USA
| | - Marian DiFiglia
- Department of Neurology, Massachusetts General Hospital, Charlestown, MA, USA
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Xie S, Naslavsky N, Caplan S. Diacylglycerol kinases in membrane trafficking. CELLULAR LOGISTICS 2015; 5:e1078431. [PMID: 27057419 DOI: 10.1080/21592799.2015.1078431] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 07/22/2015] [Accepted: 07/24/2015] [Indexed: 10/23/2022]
Abstract
Diacylglycerol kinases (DGKs) belong to a family of cytosolic kinases that regulate the phosphorylation of diacylglycerol (DAG), converting it into phosphatidic acid (PA). There are 10 known mammalian DGK isoforms, each with a different tissue distribution and substrate specificity. These differences allow regulation of cellular responses by fine-tuning the delicate balance of cellular DAG and PA. DGK isoforms are best characterized as mediators of signal transduction and immune function. However, since recent studies reveal that DAG and PA are also involved in the regulation of endocytic trafficking, it is therefore anticipated that DGKs also plays an important role in membrane trafficking. In this review, we summarize the literature discussing the role of DGK isoforms at different stages of endocytic trafficking, including endocytosis, exocytosis, endocytic recycling, and transport from/to the Golgi apparatus. Overall, these studies contribute to our understanding of the involvement of PA and DAG in endocytic trafficking, an area of research that is drawing increasing attention in recent years.
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Affiliation(s)
- Shuwei Xie
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center; University of Nebraska Medical Center ; Omaha, NE USA
| | - Naava Naslavsky
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center; University of Nebraska Medical Center ; Omaha, NE USA
| | - Steve Caplan
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center; University of Nebraska Medical Center ; Omaha, NE USA
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23
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Stones DH, Krachler AM. Dual function of a bacterial protein as an adhesin and extracellular effector of host GTPase signaling. Small GTPases 2015; 6:153-6. [PMID: 26156628 PMCID: PMC4601360 DOI: 10.1080/21541248.2015.1028609] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Bacterial pathogens often target conserved cellular mechanisms within their hosts to rewire signaling pathways and facilitate infection. Rho GTPases are important nodes within eukaryotic signaling networks and thus constitute a common target of pathogen-mediated manipulation. A diverse array of microbial mechanisms exists to interfere with Rho GTPase signaling. While targeting of GTPases by secreted bacterial effectors is a well-known strategy bacterial pathogens employ to interfere with the host, we have recently described pathogen adhesion as a novel extracellular stimulus that hijacks host GTPase signaling. The Multivalent Adhesion Molecule MAM7 from Vibrio parahaemolyticus directly binds host cell membrane lipids. The ensuing coalescence of phosphatidic acid ligands in the host membrane leads to downstream activation of RhoA and actin rearrangements. Herein, we discuss mechanistic models of lipid-mediated Rho activation and the implications from the infected host's and the pathogen's perspective.
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Affiliation(s)
- Daniel Henry Stones
- a Institute of Microbiology and Infection ; School of Biosciences ; University of Birmingham ; Edgbaston, Birmingham , United Kingdom
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24
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Abstract
ATP13A2 is a lysosomal P-type transport ATPase that has been implicated in Kufor-Rakeb syndrome and Parkinson's disease (PD), providing protection against α-synuclein, Mn(2+), and Zn(2+) toxicity in various model systems. So far, the molecular function and regulation of ATP13A2 remains undetermined. Here, we demonstrate that ATP13A2 contains a unique N-terminal hydrophobic extension that lies on the cytosolic membrane surface of the lysosome, where it interacts with the lysosomal signaling lipids phosphatidic acid (PA) and phosphatidylinositol(3,5)bisphosphate [PI(3,5)P2]. We further demonstrate that ATP13A2 accumulates in an inactive autophosphorylated state and that PA and PI(3,5)P2 stimulate the autophosphorylation of ATP13A2. In a cellular model of PD, only catalytically active ATP13A2 offers cellular protection against rotenone-induced mitochondrial stress, which relies on the availability of PA and PI(3,5)P2. Thus, the N-terminal binding of PA and PI(3,5)P2 emerges as a key to unlock the activity of ATP13A2, which may offer a therapeutic strategy to activate ATP13A2 and thereby reduce α-synuclein toxicity or mitochondrial stress in PD or related disorders.
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25
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Beznoussenko GV, Pilyugin SS, Geerts WJC, Kozlov MM, Burger KNJ, Luini A, Derganc J, Mironov AA. Trans-membrane area asymmetry controls the shape of cellular organelles. Int J Mol Sci 2015; 16:5299-333. [PMID: 25761238 PMCID: PMC4394477 DOI: 10.3390/ijms16035299] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 02/04/2015] [Accepted: 02/13/2015] [Indexed: 01/08/2023] Open
Abstract
Membrane organelles often have complicated shapes and differ in their volume, surface area and membrane curvature. The ratio between the surface area of the cytosolic and luminal leaflets (trans-membrane area asymmetry (TAA)) determines the membrane curvature within different sites of the organelle. Thus, the shape of the organelle could be critically dependent on TAA. Here, using mathematical modeling and stereological measurements of TAA during fast transformation of organelle shapes, we present evidence that suggests that when organelle volume and surface area are constant, TAA can regulate transformation of the shape of the Golgi apparatus, endosomal multivesicular bodies, and microvilli of brush borders of kidney epithelial cells. Extraction of membrane curvature by small spheres, such as COPI-dependent vesicles within the Golgi (extraction of positive curvature), or by intraluminal vesicles within endosomes (extraction of negative curvature) controls the shape of these organelles. For instance, Golgi tubulation is critically dependent on the fusion of COPI vesicles with Golgi cisternae, and vice versa, for the extraction of membrane curvature into 50–60 nm vesicles, to induce transformation of Golgi tubules into cisternae. Also, formation of intraluminal ultra-small vesicles after fusion of endosomes allows equilibration of their TAA, volume and surface area. Finally, when microvilli of the brush border are broken into vesicles and microvilli fragments, TAA of these membranes remains the same as TAA of the microvilli. Thus, TAA has a significant role in transformation of organelle shape when other factors remain constant.
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Affiliation(s)
- Galina V Beznoussenko
- The FIRC Institute of Molecular Oncology, Milan 20139, Italy.
- Consorzio Mario Negri Sud, S. Maria Imbaro, Chieti 66030, Italy.
| | - Sergei S Pilyugin
- Department of Mathematics, University of Florida, Gainesville, FL 32611-8105, USA.
| | - Willie J C Geerts
- Department of Biochemical Physiology, Institute of Biomembranes, 3584 CH Utrecht, The Netherlands.
| | - Michael M Kozlov
- Department of Physiology and Pharmacology, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Koert N J Burger
- Department of Biochemical Physiology, Institute of Biomembranes, 3584 CH Utrecht, The Netherlands.
| | - Alberto Luini
- Consiglio Nazionale delle Ricerche (CNR), Istituto di Biochimica delle Proteine, Naples 80131, Italy.
| | - Jure Derganc
- Institute of Biophysics, University of Ljubljana, 1000 Ljubljana, Slovenia.
| | - Alexander A Mironov
- The FIRC Institute of Molecular Oncology, Milan 20139, Italy.
- Consorzio Mario Negri Sud, S. Maria Imbaro, Chieti 66030, Italy.
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The C-terminal heavy-chain domain of botulinum neurotoxin a is not the only site that binds neurons, as the N-terminal heavy-chain domain also plays a very active role in toxin-cell binding and interactions. Infect Immun 2015; 83:1465-76. [PMID: 25624352 DOI: 10.1128/iai.00063-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) possess unique specificity for nerve terminals. They bind to the presynaptic membrane and then translocate intracellularly, where the light-chain endopeptidase cleaves the SNARE complex proteins, subverting the synaptic exocytosis responsible for acetylcholine release to the synaptic cleft. This inhibits acetylcholine binding to its receptor, causing paralysis. Binding, an obligate event for cell intoxication, is believed to occur through the heavy-chain C-terminal (HC) domain. It is followed by toxin translocation and entry into the cell cytoplasm, which is thought to be mediated by the heavy-chain N-terminal (HN) domain. Submolecular mapping analysis by using synthetic peptides spanning BoNT serotype A (BoNT/A) and mouse brain synaptosomes (SNPs) and protective antibodies against toxin from mice and cervical dystonia patients undergoing BoNT/A treatment revealed that not only regions of the HC domain but also regions of the HN domain are involved in the toxin binding process. Based on these findings, we expressed a peptide corresponding to the BoNT/A region comprising HN domain residues 729 to 845 (HN729-845). HN729-845 bound directly to mouse brain SNPs and substantially inhibited BoNT/A binding to SNPs. The binding involved gangliosides GT1b and GD1a and a few membrane lipids. The peptide bound to human or mouse neuroblastoma cells within 1 min. Peptide HN729-845 protected mice completely against a lethal BoNT/A dose (1.05 times the 100% lethal dose). This protective activity was obtained at a dose comparable to that of the peptide from positions 967 to 1296 in the HC domain. These findings strongly indicate that HN729-845 and, by extension, the HN domain are fully programmed and equipped to bind to neuronal cells and in the free state can even inhibit the binding of the toxin.
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27
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Reid A, Yücel D, Wood M, Llamosas E, Kant S, Crossley M, Nicholas H. The transcriptional repressor CTBP-1 functions in the nervous system of Caenorhabditis elegans to regulate lifespan. Exp Gerontol 2014; 60:153-65. [PMID: 25456848 DOI: 10.1016/j.exger.2014.09.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 09/11/2014] [Accepted: 09/13/2014] [Indexed: 01/08/2023]
Abstract
C-terminal binding proteins (CtBPs) are recruited by a variety of transcription factors to mediate gene repression. Nematode CTBP-1 has previously been shown to play a role in the regulation of lifespan; Caenorhabditis elegans strains carrying a deletion in the ctbp-1 gene showed a 10-20% increase in mean and maximal lifespan compared with wild-type control strains. We set out to identify the tissues in which CTBP-1 functions to regulate lifespan in C. elegans. Our analysis of reporter genes shows that CTBP-1 is predominantly expressed in the nervous system with lower levels detectable in the hypodermis. Tissue-specific rescue experiments demonstrated that CTBP-1 functions in the nervous system to regulate lifespan. Previously, the lifespan extension in a ctbp-1 mutant was attributed, at least in part, to the misregulation of a lipase gene, lips-7. We therefore focussed on lips-7 and found that expressing CTBP-1 solely in the nervous system of a ctbp-1 mutant significantly reduced lips-7 transcription. In addition, we studied another ctbp-1 mutant allele that also displayed a long-lived phenotype. In this case, lips-7 expression was unaffected. This observation argues that, while lips-7 may play a role in lifespan, its de-repression is not essential for the extension of lifespan phenotype. We show that a prominent site of LIPS-7 expression is the hypodermis, one of the sites of fat storage in C. elegans. Interestingly, we did not observe co-localisation of CTBP-1 and lips-7 transcription in the nervous system, indicating that CTBP-1 may be acting indirectly, in a cell non-autonomous manner. In summary, our data confirm that CTBP-1 is involved in the regulation of lips-7 transcription but suggest that it may perform additional roles in the nervous system that contribute to the regulation of longevity.
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Affiliation(s)
- Anna Reid
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia
| | - Duygu Yücel
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia
| | - Mallory Wood
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia
| | - Estelle Llamosas
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia
| | - Sashi Kant
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia
| | - Merlin Crossley
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, NSW 2052, Australia
| | - Hannah Nicholas
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW 2006, Australia.
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Morphology control of giant vesicles by composition of mixed amphiphilic random block copolymers of poly(methacrylic acid)-block-poly(methyl methacrylate-random-methacrylic acid). Colloid Polym Sci 2014. [DOI: 10.1007/s00396-014-3403-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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McMahon D, Dinh A, Kurz D, Shah D, Han GS, Carman GM, Brasaemle DL. Comparative gene identification 58/α/β hydrolase domain 5 lacks lysophosphatidic acid acyltransferase activity. J Lipid Res 2014; 55:1750-61. [PMID: 24879803 DOI: 10.1194/jlr.m051151] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Indexed: 01/07/2023] Open
Abstract
Mutations in the gene encoding comparative gene identification 58 (CGI-58)/α/β hydrolase domain 5 (ABHD5) cause Chanarin-Dorfman syndrome, characterized by excessive triacylglycerol storage in cells and tissues. CGI-58 has been identified as a coactivator of adipose TG lipase (ATGL) and a lysophosphatidic acid acyltransferase (LPAAT). We developed a molecular model of CGI-58 structure and then mutated predicted active site residues and performed LPAAT activity assays of recombinant WT and mutated CGI-58. When mutations of predicted catalytic residues failed to reduce LPAAT activity, we determined that LPAAT activity was due to a bacterial contaminant of affinity purification procedures, plsC, the sole LPAAT in Escherichia coli Purification protocols were optimized to reduce plsC contamination, in turn reducing LPAAT activity. When CGI-58 was expressed in SM2-1(DE3) cells that lack plsC, lysates lacked LPAAT activity. Additionally, mouse CGI-58 expressed in bacteria as a glutathione-S-transferase fusion protein and human CGI-58 expressed in yeast lacked LPAAT activity. Previously reported lipid binding activity of CGI-58 was revisited using protein-lipid overlays. Recombinant CGI-58 failed to bind lysophosphatidic acid, but interestingly, bound phosphatidylinositol 3-phosphate [PI(3)P] and phosphatidylinositol 5-phosphate [PI(5)P]. Prebinding CGI-58 with PI(3)P or PI(5)P did not alter its coactivation of ATGL in vitro. In summary, purified recombinant CGI-58 that is functional as an ATGL coactivator lacks LPAAT activity.
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Affiliation(s)
- Derek McMahon
- Rutgers Center for Lipid Research and Department of Nutritional Sciences and Rutgers Center for Lipid Research and Department of Food Science
| | - Anna Dinh
- Rutgers Center for Lipid Research and Department of Nutritional Sciences and Rutgers Center for Lipid Research and Department of Food Science
| | - Daniel Kurz
- Rutgers Center for Lipid Research and Department of Nutritional Sciences and Rutgers Center for Lipid Research and Department of Food Science
| | - Dharika Shah
- Rutgers Center for Lipid Research and Department of Nutritional Sciences and Rutgers Center for Lipid Research and Department of Food Science
| | - Gil-Soo Han
- Rutgers, The State University of New Jersey, New Brunswick, NJ 08901
| | - George M Carman
- Rutgers, The State University of New Jersey, New Brunswick, NJ 08901
| | - Dawn L Brasaemle
- Rutgers Center for Lipid Research and Department of Nutritional Sciences and Rutgers Center for Lipid Research and Department of Food Science
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Rocha S, De Keersmaecker H, Hutchison JA, Vanhoorelbeke K, Martens JA, Hofkens J, Uji-i H. Membrane remodeling processes induced by phospholipase action. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:4743-4751. [PMID: 24694028 DOI: 10.1021/la500121f] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Important cellular events such as division require drastic changes in the shape of the membrane. These remodeling processes can be triggered by the binding of specific proteins or by changes in membrane composition and are linked to phospholipid metabolism for which dedicated enzymes, named phospholipases, are responsible. Here wide-field fluorescence microscopy is used to visualize shape changes induced by the action of phospholipase A1 on dye-labeled supported membranes of POPC (1-palmitoyl-2-oleoly-sn-glycero-3-phosphocholine). Time-lapse imaging demonstrates that layers either shrink and disappear or fold and collapse into vesicles. These vesicles can undergo further transformations such as budding, tubulation, and pearling within 5 min of formation. Using dye-labeled phospholipases, we can monitor the presence of the enzyme at specific positions on the membrane as the shape transformations occur. Furthermore, incorporating the products of hydrolysis into POPC membranes is shown to induce transformations similar to those observed for enzyme action. The results suggest that phospholipase-mediated hydrolysis plays an important role in membrane transformations by altering the membrane composition, and a model is proposed for membrane curvature based on the presence and shape of hydrolysis products.
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Affiliation(s)
- Susana Rocha
- Molecular Imaging and Photonics, Faculty of Science and ‡Centre for Surface Chemistry and Catalysis, Faculty of Bioscience Engineering, KU Leuven , Belgium
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Kantardzhieva A, Liberman MC, Sewell WF. Quantitative analysis of ribbons, vesicles, and cisterns at the cat inner hair cell synapse: correlations with spontaneous rate. J Comp Neurol 2014; 521:3260-71. [PMID: 23787810 DOI: 10.1002/cne.23345] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 02/26/2013] [Accepted: 04/05/2013] [Indexed: 11/09/2022]
Abstract
Cochlear hair cells form ribbon synapses with terminals of the cochlear nerve. To test the hypothesis that one function of the ribbon is to create synaptic vesicles from the cisternal structures that are abundant at the base of hair cells, we analyzed the distribution of vesicles and cisterns around ribbons from serial sections of inner hair cells in the cat, and compared data from low and high spontaneous rate (SR) synapses. Consistent with the hypothesis, we identified a "sphere of influence" of 350 nm around the ribbon, with fewer cisterns and many more synaptic vesicles. Although high- and low-SR ribbons tended to be longer and thinner than high-SR ribbons, the total volume of the two ribbon types was similar. There were almost as many vesicles docked at the active zone as attached to the ribbon. The major SR-related difference was that low-SR ribbons had more synaptic vesicles intimately associated with them. Our data suggest a trend in which low-SR synapses had more vesicles attached to the ribbon (51.3 vs. 42.8), more docked between the ribbon and the membrane (12 vs. 8.2), more docked at the active zone (56.9 vs. 44.2), and more vesicles within the "sphere of influence" (218 vs. 166). These data suggest that the structural differences between high- and low-SR synapses may be more a consequence, than a determinant, of the physiological differences.
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Affiliation(s)
- Albena Kantardzhieva
- Eaton-Peabody Laboratory, Department of Otology and Laryngology, Massachusetts Eye and Ear Infirmary and Harvard Medical School, Boston, Massachusetts 02114, USA
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Pascual F, Soto-Cardalda A, Carman GM. PAH1-encoded phosphatidate phosphatase plays a role in the growth phase- and inositol-mediated regulation of lipid synthesis in Saccharomyces cerevisiae. J Biol Chem 2013; 288:35781-92. [PMID: 24196957 DOI: 10.1074/jbc.m113.525766] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae, the synthesis of phospholipids in the exponential phase of growth occurs at the expense of the storage lipid triacylglycerol. As exponential phase cells progress into the stationary phase, the synthesis of triacylglycerol occurs at the expense of phospholipids. Early work indicates a role of the phosphatidate phosphatase (PAP) in this metabolism; the enzyme produces the diacylglycerol needed for the synthesis of triacylglycerol and simultaneously controls the level of phosphatidate for the synthesis of phospholipids. Four genes (APP1, DPP1, LPP1, and PAH1) encode PAP activity in yeast, and it has been unclear which gene is responsible for the synthesis of triacylglycerol throughout growth. An analysis of lipid synthesis and composition, as well as PAP activity in various PAP mutant strains, showed the essential role of PAH1 in triacylglycerol synthesis throughout growth. Pah1p is a phosphorylated enzyme whose in vivo function is dependent on its dephosphorylation by the Nem1p-Spo7p protein phosphatase complex. nem1Δ mutant cells exhibited defects in triacylglycerol synthesis and lipid metabolism that mirrored those imparted by the pah1Δ mutation, substantiating the importance of Pah1p dephosphorylation throughout growth. An analysis of cells bearing PPAH1-lacZ and PPAH1-DPP1 reporter genes showed that PAH1 expression was induced throughout growth and that the induction in the stationary phase was stimulated by inositol supplementation. A mutant analysis indicated that the Ino2p/Ino4p/Opi1p regulatory circuit and transcription factors Gis1p and Rph1p mediated this regulation.
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Affiliation(s)
- Florencia Pascual
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
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Mironov AA, Sesorova IV, Beznoussenko GV. Golgi's way: a long path toward the new paradigm of the intra-Golgi transport. Histochem Cell Biol 2013; 140:383-93. [PMID: 24068461 DOI: 10.1007/s00418-013-1141-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2013] [Indexed: 11/28/2022]
Abstract
The transport of proteins and lipids is one of the main cellular functions. The vesicular model, compartment (or cisterna) maturation model, and the diffusion model compete with each other for the right to be the paradigm within the field of the intra-Golgi transport. These models have significant difficulties explaining the existing experimental data. Recently, we proposed the kiss-and-run (KAR) model of intra-Golgi transport (Mironov and Beznoussenko in Int J Mol Sci 13(6):6800-6819, 2012), which can be symmetric, when fusion and fission occur in the same location, and asymmetric, when fusion and fission take place at different sites. Here, we compare the ability of main models of the intra-Golgi transport to explain the existing results examining the evidence in favor and against each model. We propose that the KAR model has the highest potential for the explanation of the majority of experimental observations existing within the field of intracellular transport.
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Affiliation(s)
- Alexander A Mironov
- Istituto di Oncologia Molecolare di Fondazione Italiana per la Ricerca sul Cancro, 20139, Milan, Italy,
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Components of the CtBP1/BARS-dependent fission machinery. Histochem Cell Biol 2013; 140:407-21. [PMID: 23996193 DOI: 10.1007/s00418-013-1138-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/20/2013] [Indexed: 01/12/2023]
Abstract
The brefeldin A ADP-ribosylated substrate, a member of the C-terminal-binding protein family that is referred to as CtBP1/BARS, is a dual-function protein that acts as a transcriptional co-repressor in the nucleus and as an inducer of membrane fission in the cytoplasm. In this review, we first discuss the mechanisms that enable CtBP1/BARS to shift between the nuclear transcriptional co-repressor and the cytosolic fission-inducing activities. Then, we focus on the role of CtBP1/BARS in membrane fission. CtBP1/BARS controls several fission events including macropinocytosis, fluid-phase endocytosis, COPI-coated vesicle formation, basolaterally directed post-Golgi carrier formation, and Golgi partitioning in mitosis. We report on recent advances in our understanding of the CtBP1/BARS membrane fission machineries that operate at the trans-side and at the cis-side of the Golgi complex. Specifically, we discuss how these machineries are assembled and regulated, and how they operate in the formation of the basolaterally directed post-Golgi carriers.
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Molecular mechanism and functional role of brefeldin A-mediated ADP-ribosylation of CtBP1/BARS. Proc Natl Acad Sci U S A 2013; 110:9794-9. [PMID: 23716697 DOI: 10.1073/pnas.1222413110] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
ADP-ribosylation is a posttranslational modification that modulates the functions of many target proteins. We previously showed that the fungal toxin brefeldin A (BFA) induces the ADP-ribosylation of C-terminal-binding protein-1 short-form/BFA-ADP-ribosylation substrate (CtBP1-S/BARS), a bifunctional protein with roles in the nucleus as a transcription factor and in the cytosol as a regulator of membrane fission during intracellular trafficking and mitotic partitioning of the Golgi complex. Here, we report that ADP-ribosylation of CtBP1-S/BARS by BFA occurs via a nonconventional mechanism that comprises two steps: (i) synthesis of a BFA-ADP-ribose conjugate by the ADP-ribosyl cyclase CD38 and (ii) covalent binding of the BFA-ADP-ribose conjugate into the CtBP1-S/BARS NAD(+)-binding pocket. This results in the locking of CtBP1-S/BARS in a dimeric conformation, which prevents its binding to interactors known to be involved in membrane fission and, hence, in the inhibition of the fission machinery involved in mitotic Golgi partitioning. As this inhibition may lead to arrest of the cell cycle in G2, these findings provide a strategy for the design of pharmacological blockers of cell cycle in tumor cells that express high levels of CD38.
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C-Terminal Binding Protein: A Molecular Link between Metabolic Imbalance and Epigenetic Regulation in Breast Cancer. Int J Cell Biol 2013; 2013:647975. [PMID: 23762064 PMCID: PMC3671672 DOI: 10.1155/2013/647975] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 04/14/2013] [Accepted: 04/15/2013] [Indexed: 12/21/2022] Open
Abstract
The prevalence of obesity has given rise to significant global concerns as numerous population-based studies demonstrate an incontrovertible association between obesity and breast cancer. Mechanisms proposed to account for this linkage include exaggerated levels of carbohydrate substrates, elevated levels of circulating mitogenic hormones, and inflammatory cytokines that impinge on epithelial programming in many tissues. Moreover, recently many scientists have rediscovered the observation, first described by Otto Warburg nearly a century ago, that most cancer cells undergo a dramatic metabolic shift in energy utilization and expenditure that fuels and supports the cellular expansion associated with malignant proliferation. This shift in substrate oxidation comes at the cost of sharp changes in the levels of the high energy intermediate, nicotinamide adenine dinucleotide (NADH). In this review, we discuss a novel example of how shifts in the concentration and flux of substrates metabolized and generated during carbohydrate metabolism represent components of a signaling network that can influence epigenetic regulatory events in the nucleus. We refer to this regulatory process as "metabolic transduction" and describe how the C-terminal binding protein (CtBP) family of NADH-dependent nuclear regulators represents a primary example of how cellular metabolic status can influence epigenetic control of cellular function and fate.
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Arisz SA, Munnik T. Use of phospholipase A2 for the production of lysophospholipids. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2013; 1009:63-8. [PMID: 23681524 DOI: 10.1007/978-1-62703-401-2_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Biological lipid extracts often contain small amounts of lysophospholipids (LPLs). Since different functions are emerging for LPLs in lipid metabolism and signalling, there is need for a reliable and cost-effective method for their identification. For this purpose, authentic LPL standards have to be synthesized from phosphoglycerides by PLA2 digestion in vitro. PLA2 specifically hydrolyzes the fatty acid ester linkage in the sn-2-position of phospholipids to liberate sn-2-linked fatty acids and the corresponding LPL. Due to this specificity, the reaction is also useful to analyze the positional distribution of fatty acids within membrane phospholipids. This chapter describes the in vitro generation of LPLs from diacyl-phosphoglycerides and their TLC analysis.
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Affiliation(s)
- Steven A Arisz
- Swammerdam Institute for Life Sciences, Section Plant Physiology, University of Amsterdam, Amsterdam, The Netherlands
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Bai Y, Vaddepalli P, Fulton L, Bhasin H, Hülskamp M, Schneitz K. ANGUSTIFOLIA is a central component of tissue morphogenesis mediated by the atypical receptor-like kinase STRUBBELIG. BMC PLANT BIOLOGY 2013; 13:16. [PMID: 23368817 PMCID: PMC3599385 DOI: 10.1186/1471-2229-13-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 01/29/2013] [Indexed: 05/03/2023]
Abstract
BACKGROUND During plant tissue morphogenesis cells have to coordinate their behavior to allow the generation of the size, shape and cellular patterns that distinguish an organ. Despite impressive progress the underlying signaling pathways remain largely unexplored. In Arabidopsis thaliana, the atypical leucine-rich repeat receptor-like kinase STRUBBELIG (SUB) is involved in signal transduction in several developmental processes including the formation of carpels, petals, ovules and root hair patterning. The three STRUBBELIG-LIKE MUTANT (SLM) genes DETORQUEO (DOQ), QUIRKY (QKY) and ZERZAUST (ZET) are considered central elements of SUB-mediated signal transduction pathways as corresponding mutants share most phenotypic aspects with sub mutants. RESULTS Here we show that DOQ corresponds to the previously identified ANGUSTIFOLIA gene. The genetic analysis revealed that the doq-1 mutant exhibits all additional mutant phenotypes and conversely that other an alleles show the slm phenotypes. We further provide evidence that SUB and AN physically interact and that AN is not required for subcellular localization of SUB. CONCLUSIONS Our data suggest that AN is involved in SUB signal transduction pathways. In addition, they reveal previously unreported functions of AN in several biological processes, such as ovule development, cell morphogenesis in floral meristems, and root hair patterning. Finally, SUB and AN may directly interact at the plasma membrane to mediate SUB-dependent signaling.
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Affiliation(s)
- Yang Bai
- Botanisches Institut III, Universität Köln, Zülpicher Straße 47b, 50674, Köln, Germany
- Present address: Department of Plant Microbe Interactions, Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829, Köln, Germany
| | - Prasad Vaddepalli
- Entwicklungsbiologie der Pflanzen, Wissenschaftszentrum Weihenstephan, Technische Universität München, Emil-Ramann-Str. 4, 85354, Freising, Germany
| | - Lynette Fulton
- Entwicklungsbiologie der Pflanzen, Wissenschaftszentrum Weihenstephan, Technische Universität München, Emil-Ramann-Str. 4, 85354, Freising, Germany
- Present address: School of Biological Sciences, Monash University, 3800, Melbourne, VIC, Australia
| | - Hemal Bhasin
- Botanisches Institut III, Universität Köln, Zülpicher Straße 47b, 50674, Köln, Germany
| | - Martin Hülskamp
- Botanisches Institut III, Universität Köln, Zülpicher Straße 47b, 50674, Köln, Germany
| | - Kay Schneitz
- Entwicklungsbiologie der Pflanzen, Wissenschaftszentrum Weihenstephan, Technische Universität München, Emil-Ramann-Str. 4, 85354, Freising, Germany
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Chae M, Carman GM. Characterization of the yeast actin patch protein App1p phosphatidate phosphatase. J Biol Chem 2013; 288:6427-37. [PMID: 23335564 DOI: 10.1074/jbc.m112.449629] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Yeast App1p is a phosphatidate phosphatase (PAP) that associates with endocytic proteins at cortical actin patches. App1p, which catalyzes the conversion of phosphatidate (PA) to diacylglycerol, is unique among Mg(2+)-dependent PAP enzymes in that its reaction is not involved with de novo lipid synthesis. Instead, App1p PAP is thought to play a role in endocytosis because its substrate and product facilitate membrane fission/fusion events and regulate enzymes that govern vesicular movement. App1p PAP was purified from yeast and characterized with respect to its enzymological, kinetic, and regulatory properties. Maximum PAP activity was dependent on Triton X-100 (20 mm), PA (2 mm), Mg(2+) (0.5 mm), and 2-mercaptoethanol (10 mm) at pH 7.5 and 30 °C. Analysis of surface dilution kinetics with Triton X-100/PA-mixed micelles yielded constants for surface binding (Ks(A) = 11 mm), interfacial PA binding (Km(B) = 4.2 mol %), and catalytic efficiency (Vmax = 557 μmol/min/mg). The activation energy, turnover number, and equilibrium constant were 16.5 kcal/mol, 406 s(-1), and 16.2, respectively. PAP activity was stimulated by anionic lipids (cardiolipin, phosphatidylglycerol, phosphatidylserine, and CDP-diacylglycerol) and inhibited by zwitterionic (phosphatidylcholine and phosphatidylethanolamine) and cationic (sphinganine) lipids, nucleotides (ATP and CTP), N-ethylmaleimide, propranolol, phenylglyoxal, and divalent cations (Ca(2+), Mn(2+), and Zn(2+)). App1p also utilized diacylglycerol pyrophosphate and lyso-PA as substrates with specificity constants 4- and 7-fold lower, respectively, when compared with PA.
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Affiliation(s)
- Minjung Chae
- Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901, USA
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Chae M, Han GS, Carman GM. The Saccharomyces cerevisiae actin patch protein App1p is a phosphatidate phosphatase enzyme. J Biol Chem 2012; 287:40186-96. [PMID: 23071111 PMCID: PMC3504732 DOI: 10.1074/jbc.m112.421776] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 10/11/2012] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Phosphatidate phosphatase (PAP) plays diverse roles in lipid metabolism and cell signaling. RESULTS A novel yeast PAP is identified as the actin patch protein encoded by APP1. CONCLUSION APP1 and other known genes (PAH1, DPP1, LPP1) are responsible for all detectable PAP activity in yeast. SIGNIFICANCE Identification of App1p as a PAP enzyme will facilitate the understanding of its cellular function. Phosphatidate phosphatase (PAP) catalyzes the dephosphorylation of phosphatidate to yield diacylglycerol. In the yeast Saccharomyces cerevisiae, PAP is encoded by PAH1, DPP1, and LPP1. The presence of PAP activity in the pah1Δ dpp1Δ lpp1Δ triple mutant indicated another gene(s) encoding the enzyme. We purified PAP from the pah1Δ dpp1Δ lpp1Δ triple mutant by salt extraction of mitochondria followed by chromatography with DE52, Affi-Gel Blue, phenyl-Sepharose, MonoQ, and Superdex 200. Liquid chromatography/tandem mass spectrometry analysis of a PAP-enriched sample revealed multiple putative phosphatases. By analysis of PAP activity in mutants lacking each of the proteins, we found that APP1, a gene whose molecular function has been unknown, confers ~30% PAP activity of wild type cells. The overexpression of APP1 in the pah1Δ dpp1Δ lpp1Δ mutant exhibited a 10-fold increase in PAP activity. The PAP activity shown by App1p heterologously expressed in Escherichia coli confirmed that APP1 is the structural gene for the enzyme. Introduction of the app1Δ mutation into the pah1Δ dpp1Δ lpp1Δ triple mutant resulted in a complete loss of PAP activity, indicating that distinct PAP enzymes in S. cerevisiae are encoded by APP1, PAH1, DPP1, and LPP1. Lipid analysis of cells lacking the PAP genes, singly or in combination, showed that Pah1p is the only PAP involved in the synthesis of triacylglycerol as well as in the regulation of phospholipid synthesis. App1p, which shows interactions with endocytic proteins, may play a role in vesicular trafficking through its PAP activity.
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Affiliation(s)
- Minjung Chae
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - Gil-Soo Han
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
| | - George M. Carman
- From the Department of Food Science, Rutgers Center for Lipid Research, and New Jersey Institute for Food, Nutrition, and Health, Rutgers University, New Brunswick, New Jersey 08901
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Abstract
The striking morphology of the Golgi complex has fascinated cell biologists since its discovery over 100 years ago. Yet, despite intense efforts to understand how membrane flow relates to Golgi form and function, this organelle continues to baffle cell biologists and biochemists alike. Fundamental questions regarding Golgi function, while hotly debated, remain unresolved. Historically, Golgi function has been described from a protein-centric point of view, but we now appreciate that conceptual frameworks for how lipid metabolism is integrated with Golgi biogenesis and function are essential for a mechanistic understanding of this fascinating organelle. It is from a lipid-centric perspective that we discuss the larger question of Golgi dynamics and membrane trafficking. We review the growing body of evidence for how lipid metabolism is integrally written into the engineering of the Golgi system and highlight questions for future study.
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Affiliation(s)
- Vytas A Bankaitis
- Department of Cell and Developmental Biology, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7090, USA.
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42
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Molecular anatomy and physiology of exocytosis in sensory hair cells. Cell Calcium 2012; 52:327-37. [DOI: 10.1016/j.ceca.2012.05.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Revised: 05/08/2012] [Accepted: 05/14/2012] [Indexed: 11/23/2022]
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Hübler D, Rankovic M, Richter K, Lazarevic V, Altrock WD, Fischer KD, Gundelfinger ED, Fejtova A. Differential spatial expression and subcellular localization of CtBP family members in rodent brain. PLoS One 2012; 7:e39710. [PMID: 22745816 PMCID: PMC3382178 DOI: 10.1371/journal.pone.0039710] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 05/30/2012] [Indexed: 12/23/2022] Open
Abstract
C-terminal binding proteins (CtBPs) are well-characterized nuclear transcriptional co-regulators. In addition, cytoplasmic functions were discovered for these ubiquitously expressed proteins. These include the involvement of the isoform CtBP1-S/BARS50 in cellular membrane-trafficking processes and a role of the isoform RIBEYE as molecular scaffolds in ribbons, the presynaptic specializations of sensory synapses. CtBPs were suggested to regulate neuronal differentiation and they were implied in the control of gene expression during epileptogenesis. However, the expression patterns of CtBP family members in specific brain areas and their subcellular localizations in neurons in situ are largely unknown. Here, we performed comprehensive assessment of the expression of CtBP1 and CtBP2 in mouse brain at the microscopic and the ultra-structural levels using specific antibodies. We quantified and compared expression levels of both CtBPs in biochemically isolated brain fractions containing cellular nuclei or synaptic compartment. Our study demonstrates differential regional and subcellular expression patterns for the two CtBP family members in brain and reveals a previously unknown synaptic localization for CtBP2 in particular brain regions. Finally, we propose a mechanism of differential synapto-nuclear targeting of its splice variants CtBP2-S and CtBP2-L in neurons.
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Affiliation(s)
- Diana Hübler
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Marija Rankovic
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Karin Richter
- Institute of Biochemistry and Cell Biology, Otto-von-Guericke University, Magdeburg, Germany
| | - Vesna Lazarevic
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
- German Center for Neurodegenerative Disorders (DZNE), Magdeburg Branch, Magdeburg, Germany
| | - Wilko D. Altrock
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Klaus-Dieter Fischer
- Institute of Biochemistry and Cell Biology, Otto-von-Guericke University, Magdeburg, Germany
| | - Eckart D. Gundelfinger
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Anna Fejtova
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, Magdeburg, Germany
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Regulation of the Golgi complex by phospholipid remodeling enzymes. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1821:1078-88. [PMID: 22562055 DOI: 10.1016/j.bbalip.2012.04.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 03/15/2012] [Accepted: 04/13/2012] [Indexed: 11/23/2022]
Abstract
The mammalian Golgi complex is a highly dynamic organelle consisting of stacks of flattened cisternae with associated coated vesicles and membrane tubules that contribute to cargo import and export, intra-cisternal trafficking, and overall Golgi architecture. At the morphological level, all of these structures are continuously remodeled to carry out these trafficking functions. Recent advances have shown that continual phospholipid remodeling by phospholipase A (PLA) and lysophospholipid acyltransferase (LPAT) enzymes, which deacylate and reacylate Golgi phospholipids, respectively, contributes to this morphological remodeling. Here we review the identification and characterization of four cytoplasmic PLA enzymes and one integral membrane LPAT that participate in the dynamic functional organization of the Golgi complex, and how some of these enzymes are integrated to determine the relative abundance of COPI vesicle and membrane tubule formation. This article is part of a Special Issue entitled Lipids and Vesicular Transport.
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Bucci C, Bakke O, Progida C. Charcot-Marie-Tooth disease and intracellular traffic. Prog Neurobiol 2012; 99:191-225. [PMID: 22465036 PMCID: PMC3514635 DOI: 10.1016/j.pneurobio.2012.03.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Revised: 12/23/2011] [Accepted: 03/13/2012] [Indexed: 12/23/2022]
Abstract
Mutations of genes whose primary function is the regulation of membrane traffic are increasingly being identified as the underlying causes of various important human disorders. Intriguingly, mutations in ubiquitously expressed membrane traffic genes often lead to cell type- or organ-specific disorders. This is particularly true for neuronal diseases, identifying the nervous system as the most sensitive tissue to alterations of membrane traffic. Charcot-Marie-Tooth (CMT) disease is one of the most common inherited peripheral neuropathies. It is also known as hereditary motor and sensory neuropathy (HMSN), which comprises a group of disorders specifically affecting peripheral nerves. This peripheral neuropathy, highly heterogeneous both clinically and genetically, is characterized by a slowly progressive degeneration of the muscle of the foot, lower leg, hand and forearm, accompanied by sensory loss in the toes, fingers and limbs. More than 30 genes have been identified as targets of mutations that cause CMT neuropathy. A number of these genes encode proteins directly or indirectly involved in the regulation of intracellular traffic. Indeed, the list of genes linked to CMT disease includes genes important for vesicle formation, phosphoinositide metabolism, lysosomal degradation, mitochondrial fission and fusion, and also genes encoding endosomal and cytoskeletal proteins. This review focuses on the link between intracellular transport and CMT disease, highlighting the molecular mechanisms that underlie the different forms of this peripheral neuropathy and discussing the pathophysiological impact of membrane transport genetic defects as well as possible future ways to counteract these defects.
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Affiliation(s)
- Cecilia Bucci
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Via Provinciale Monteroni, 73100 Lecce, Italy.
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46
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A 14-3-3γ dimer-based scaffold bridges CtBP1-S/BARS to PI(4)KIIIβ to regulate post-Golgi carrier formation. Nat Cell Biol 2012; 14:343-54. [PMID: 22366688 DOI: 10.1038/ncb2445] [Citation(s) in RCA: 233] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 01/17/2012] [Indexed: 11/08/2022]
Abstract
Large pleiomorphic carriers leave the Golgi complex for the plasma membrane by en bloc extrusion of specialized tubular domains, which then undergo fission. Several components of the underlying molecular machinery have been identified, including those involved in the budding/initiation of tubular carrier precursors (for example, the phosphoinositide kinase PI(4)KIIIβ, the GTPase ARF, and FAPP2), and in the fission of these precursors (for example, PKD, CtBP1-S/BARS). However, how these proteins interact to bring about carrier formation is poorly understood. Here, we describe a protein complex that mediates carrier formation and contains budding and fission molecules, as well as other molecules, such as the adaptor protein 14-3-3γ. Specifically, we show that 14-3-3γ dimers bridge CtBP1-S/BARS with PI(4)KIIIβ, and that the resulting complex is stabilized by phosphorylation by PKD and PAK. Disrupting the association of these proteins inhibits the fission of elongating carrier precursors, indicating that this complex couples the carrier budding and fission processes.
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Abstract
Ribbon synapses continuously transmit graded membrane potential changes into changes of synaptic vesicle exocytosis and rely on intense synaptic membrane trafficking. The synaptic ribbon is considered central to this process. In the present study we asked whether tonically active ribbon synapses are associated with the generation of certain lipids, specifically the highly active signaling phospholipid phosphatidic acid (PA). Using PA-sensor proteins, we demonstrate that PA is enriched at mouse retinal ribbon synapses in close vicinity to the synaptic ribbon in situ. As shown by heterologous expression, RIBEYE, a main component of synaptic ribbons, is responsible for PA binding at synaptic ribbons. Furthermore, RIBEYE is directly involved in the synthesis of PA. Using various independent substrate binding and enzyme assays, we demonstrate that the B domain of RIBEYE possesses lysophosphatidic acid (LPA) acyltransferase (LPAAT) activity, which leads to the generation of PA from LPA. Since an LPAAT-deficient RIBEYE mutant does not recruit PA-binding proteins to artificial synaptic ribbons, whereas wild-type RIBEYE supports PA binding, we conclude that the LPAAT activity of the RIBEYE(B) domain is a physiologically relevant source of PA generation at the synaptic ribbon. We propose that PA generated at synaptic ribbons likely facilitates synaptic vesicle trafficking.
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Disruption of the phospholipase D gene attenuates the virulence of Aspergillus fumigatus. Infect Immun 2011; 80:429-40. [PMID: 22083709 DOI: 10.1128/iai.05830-11] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Aspergillus fumigatus is the most prevalent airborne fungal pathogen that induces serious infections in immunocompromised patients. Phospholipases are key enzymes in pathogenic fungi that cleave host phospholipids, resulting in membrane destabilization and host cell penetration. However, knowledge of the impact of phospholipases on A. fumigatus virulence is rather limited. In this study, disruption of the pld gene encoding phospholipase D (PLD), an important member of the phospholipase protein family in A. fumigatus, was confirmed to significantly decrease both intracellular and extracellular PLD activity of A. fumigatus. The pld gene disruption did not alter conidial morphological characteristics, germination, growth, and biofilm formation but significantly suppressed the internalization of A. fumigatus into A549 epithelial cells without affecting conidial adhesion to epithelial cells. Importantly, the suppressed internalization was fully rescued in the presence of 100 μM phosphatidic acid, the PLD product. Indeed, complementation of pld restored the PLD activity and internalization capacity of A. fumigatus. Phagocytosis of A. fumigatus conidia by J774 macrophages was not affected by the absence of the pld gene. Pretreatment of conidia with 1-butanol and a specific PLD inhibitor decreased the internalization of A. fumigatus into A549 epithelial cells but had no effect on phagocytosis by J774 macrophages. Finally, loss of the pld gene attenuated the virulence of A. fumigatus in mice immunosuppressed with hydrocortisone acetate but not with cyclophosphamide. These data suggest that PLD of A. fumigatus regulates its internalization into lung epithelial cells and may represent an important virulence factor for A. fumigatus infection.
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Abstract
A variety of secretory cargoes move through the Golgi, but the pathways and mechanisms of this traffic are still being debated. Here, we evaluate the strengths and weaknesses of five current models for Golgi traffic: (1) anterograde vesicular transport between stable compartments, (2) cisternal progression/maturation, (3) cisternal progression/maturation with heterotypic tubular transport, (4) rapid partitioning in a mixed Golgi, and (5) stable compartments as cisternal progenitors. Each model is assessed for its ability to explain a set of key observations encompassing multiple cell types. No single model can easily explain all of the observations from diverse organisms. However, we propose that cisternal progression/maturation is the best candidate for a conserved core mechanism of Golgi traffic, and that some cells elaborate this core mechanism by means of heterotypic tubular transport between cisternae.
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Affiliation(s)
- Benjamin S Glick
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois 60637, USA.
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50
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Arisz SA, Munnik T. The salt stress-induced LPA response in Chlamydomonas is produced via PLA₂ hydrolysis of DGK-generated phosphatidic acid. J Lipid Res 2011; 52:2012-20. [PMID: 21900174 DOI: 10.1194/jlr.m016873] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The unicellular green alga Chlamydomonas has frequently been used as a eukaryotic model system to study intracellular phospholipid signaling pathways in response to environmental stresses. Earlier, we found that hypersalinity induced a rapid increase in the putative lipid second messenger, phosphatidic acid (PA), which was suggested to be generated via activation of a phospholipase D (PLD) pathway and the combined action of a phospholipase C/diacylglycerol kinase (PLC/DGK) pathway. Lysophosphatidic acid (LPA) was also increased and was suggested to reflect a phospholipase A₂ (PLA₂) activity based on pharmacological evidence. The question of PA's and LPA's origin is, however, more complicated, especially as both function as precursors in the biosynthesis of phospho- and galactolipids. To address this complexity, a combination of fatty acid-molecular species analysis and in vivo ³²P-radiolabeling was performed. Evidence is provided that LPA is formed from a distinct pool of PA characterized by a high α-linolenic acid (18:3n-3) content. This molecular species was highly enriched in the polyphosphoinositide fraction, which is the substrate for PLC to form diacylglycerol. Together with differential ³²P-radiolabeling studies and earlier PLD-transphosphatidylation and PLA₂-inhibitor assays, the data were consistent with the hypothesis that the salt-induced LPA response is primarily generated through PLA₂-mediated hydrolysis of DGK-generated PA and that PLD or de novo synthesis [via endoplasmic reticulum - or plastid-localized routes] is not a major contributor.
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Affiliation(s)
- Steven A Arisz
- Section Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
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