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Wang C, Chang CC, Chi JT, Yuan F. Sucrose Treatment Enhances the Electrotransfer of DNA by Activating Phospholipase A2. Pharmaceutics 2024; 16:475. [PMID: 38675136 PMCID: PMC11054232 DOI: 10.3390/pharmaceutics16040475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 03/08/2024] [Accepted: 03/25/2024] [Indexed: 04/28/2024] Open
Abstract
Our previous study discovered that sucrose and other non-reducing sugars (e.g., trehalose and raffinose) could be used to improve the electrotransfer (ET) of molecular cargo, including DNA, mRNA, and ribonucleoprotein in various cell lines and primary human cells in vitro and in vivo. To understand the molecular mechanisms of this improvement, we used RNA sequencing technology to analyze changes in the cell transcriptome after sucrose treatment. The results from our analysis demonstrated that the sucrose treatment upregulated phospholipase A2 and V-ATPase gene families, which could potentially influence the acidity of intracellular vesicles through augmenting vesicle fusion and the influx of proton, respectively. To determine how this upregulation affects ET efficiency, we treated cells with pharmaceutical inhibitors of phospholipase A2 and V-ATPase. The data demonstrated that the treatment with the phospholipase A2 inhibitor could reverse the ET improvement elicited by the sucrose treatment. The V-ATPase inhibitor treatment either had little influence or further enhanced the effect of the sucrose treatment on the ET efficiency. These observations provide a molecular explanation for our previous findings, demonstrating that the sucrose treatment primarily enhanced the ET efficiency by promoting vesicle trafficking and fusion through the activation of phospholipase A2.
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Affiliation(s)
- Chunxi Wang
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Chun-Chi Chang
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Jen-Tsan Chi
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Fan Yuan
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
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Xu Y, Li D, Su G, Cai S. The effect of A2E on lysosome membrane permeability during blue light-induced human RPEs apoptosis. BMC Ophthalmol 2022; 22:241. [PMID: 35641967 PMCID: PMC9158258 DOI: 10.1186/s12886-022-02464-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 05/24/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND To investigate the effect of N-retinyl-N-retinylidene ethanolamine (A2E) on lysosome membrane permeability (LMP) during blue light-induced human retinal pigment epithelium cells (RPEs) apoptosis. METHODS By building an A2E and blue light irradiation inducing RPEs damage model, the CCK-8 assay was used to detect RPEs viability loaded with different concentrations of A2E after different culturing time to determine the optimum A2E loading concentration. And the RPEs fluorescence intensity changes were observed by fluorescence microscopy loaded with different concentration of A2E. The RPEs were divided into four groups randomly: control group, A2E-loaded group, blue light irradiation group, and A2E-loaded + blue light irradiation group. Annexin V-FITC/PI and TUNEL/DAPI methods were used to detect RPEs apoptotic rate. Laser scanning confocal microscopy (LSCM) was used to observe RPEs LMP changes stained by acridine orange (AO) method. RESULTS The CCK-8 result showed a downward trend in cells viability of RPEs loaded with increasing concentration of A2E and extending culturing time. The optimum A2E loading concentration was determined at 25 μmol/L. With increasing A2E loading concentrations, the intensity of fluorescence in RPEs decreased gradually. The RPEs apoptotic rate in blue light irradiation + A2E-loaded group was significantly higher than those in other three groups detected by Annexin V-FITC/PI method, which was similar to TUNEL/DAPI's result. After AO staining, cytoplasmic and nucleolar RNAs emits green fluorescence; lysosomes emit red fluorescence. Through the interference of A2E and blue light on RPEs, red fluorescent leakage from the lysosomes (means LMP increasing) can be observed. The mean red fluorescence intensity was chosen as the statistics indicator to estimate LMP change in RPEs cultured in vitro. Compared with the control group, the red fluorescence intensity decreased in A2E-loaded group, blue light irradiation group, and blue light irradiation + A2E-loaded group. Meanwhile, the mean red fluorescence intensity in blue light irradiation + A2E-loaded group was the lowest. CONCLUSIONS Both A2E-loaded and blue light irradiation could induce human RPEs apoptosis, and the two factors had a synergistic effect. In addition, both A2E and blue light can lead to LMP increasing, which indicated LMP change might be the upstream part in inducing mitochondrion-dependent apoptotic pathway. These data provided evidence that A2E as the most important auto-fluorescence substance in lipofuscin is an initiator of blue light-mediated damage of RPEs and participate in pathogenesis of retinal degenerative diseases in humans.
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Affiliation(s)
- Yan Xu
- Department of Ophthalmology, Affiliated Hospital of Zunyi Medical University, No.149 Dalian Road, Zunyi, 563000, Guizhou, China
- Department of Ophthalmology, HwaMei Hospital, University of Chinese Academy of Sciences, Ningbo No.2 Hospital, Ningbo, Zhejiang, China
| | - Dan Li
- Department of Ophthalmology, Affiliated Hospital of Zunyi Medical University, No.149 Dalian Road, Zunyi, 563000, Guizhou, China
- Department of Ophthalmology, The People's Hospital of Longchang, Neijiang, Sichuan, China
| | - Gang Su
- Department of Ophthalmology, Affiliated Hospital of Zunyi Medical University, No.149 Dalian Road, Zunyi, 563000, Guizhou, China
- Guizhou Eye Hospital, Zunyi, Guizhou, China
- Guizhou Provincial Branch of National Eye Disease Clinical Medicine Research Center, Zunyi, Guizhou, China
- Special Key Laboratory of Ocular Diseases of Guizhou Province, Zunyi Medical University, Zunyi, Guizhou, China
| | - Shanjun Cai
- Department of Ophthalmology, Affiliated Hospital of Zunyi Medical University, No.149 Dalian Road, Zunyi, 563000, Guizhou, China.
- Guizhou Eye Hospital, Zunyi, Guizhou, China.
- Guizhou Provincial Branch of National Eye Disease Clinical Medicine Research Center, Zunyi, Guizhou, China.
- Special Key Laboratory of Ocular Diseases of Guizhou Province, Zunyi Medical University, Zunyi, Guizhou, China.
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3
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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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Eaton AF, Merkulova M, Brown D. The H +-ATPase (V-ATPase): from proton pump to signaling complex in health and disease. Am J Physiol Cell Physiol 2020; 320:C392-C414. [PMID: 33326313 PMCID: PMC8294626 DOI: 10.1152/ajpcell.00442.2020] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A primary function of the H+-ATPase (or V-ATPase) is to create an electrochemical proton gradient across eukaryotic cell membranes, which energizes fundamental cellular processes. Its activity allows for the acidification of intracellular vesicles and organelles, which is necessary for many essential cell biological events to occur. In addition, many specialized cell types in various organ systems such as the kidney, bone, male reproductive tract, inner ear, olfactory mucosa, and more, use plasma membrane V-ATPases to perform specific activities that depend on extracellular acidification. It is, however, increasingly apparent that V-ATPases are central players in many normal and pathophysiological processes that directly influence human health in many different and sometimes unexpected ways. These include cancer, neurodegenerative diseases, diabetes, and sensory perception, as well as energy and nutrient-sensing functions within cells. This review first covers the well-established role of the V-ATPase as a transmembrane proton pump in the plasma membrane and intracellular vesicles and outlines factors contributing to its physiological regulation in different cell types. This is followed by a discussion of the more recently emerging unconventional roles for the V-ATPase, such as its role as a protein interaction hub involved in cell signaling, and the (patho)physiological implications of these interactions. Finally, the central importance of endosomal acidification and V-ATPase activity on viral infection will be discussed in the context of the current COVID-19 pandemic.
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Affiliation(s)
- Amity F Eaton
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Maria Merkulova
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Dennis Brown
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
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5
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Miner GE, Sullivan KD, Zhang C, Hurst LR, Starr ML, Rivera-Kohr DA, Jones BC, Guo A, Fratti RA. Copper blocks V-ATPase activity and SNARE complex formation to inhibit yeast vacuole fusion. Traffic 2019; 20:841-850. [PMID: 31368617 DOI: 10.1111/tra.12683] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/22/2019] [Accepted: 07/22/2019] [Indexed: 12/23/2022]
Abstract
The accumulation of copper in organisms can lead to altered functions of various pathways and become cytotoxic through the generation of reactive oxygen species. In yeast, cytotoxic metals such as Hg+ , Cd2+ and Cu2+ are transported into the lumen of the vacuole through various pumps. Copper ions are initially transported into the cell by the copper transporter Ctr1 at the plasma membrane and sequestered by chaperones and other factors to prevent cellular damage by free cations. Excess copper ions can subsequently be transported into the vacuole lumen by an unknown mechanism. Transport across membranes requires the reduction of Cu2+ to Cu+ . Labile copper ions can interact with membranes to alter fluidity, lateral phase separation and fusion. Here we found that CuCl2 potently inhibited vacuole fusion by blocking SNARE pairing. This was accompanied by the inhibition of V-ATPase H+ pumping. Deletion of the vacuolar reductase Fre6 had no effect on the inhibition of fusion by copper. This suggests that Cu2+ is responsible for the inhibition of vacuole fusion and V-ATPase function. This notion is supported by the differential effects of chelators. The Cu2+ -specific chelator triethylenetetramine rescued fusion, whereas the Cu+ -specific chelator bathocuproine disulfonate had no effect on the inhibited fusion.
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Affiliation(s)
- Gregory E Miner
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Katherine D Sullivan
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Chi Zhang
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Logan R Hurst
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Matthew L Starr
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - David A Rivera-Kohr
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Brandon C Jones
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Annie Guo
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Rutilio A Fratti
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois.,Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois
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Bhasne K, Mukhopadhyay S. Formation of Heterotypic Amyloids: α-Synuclein in Co-Aggregation. Proteomics 2018; 18:e1800059. [PMID: 30216674 DOI: 10.1002/pmic.201800059] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 08/28/2018] [Indexed: 12/13/2022]
Abstract
Protein misfolding resulting in the formation of ordered amyloid aggregates is associated with a number of devastating human diseases. Intrinsically disordered proteins (IDPs) do not autonomously fold up into a unique stable conformation and remain as an ensemble of rapidly fluctuating conformers. Many IDPs are prone to convert into the β-rich amyloid state. One such amyloidogenic IDP is α-synuclein that is involved in Parkinson's disease. Recent studies have indicated that other neuronal proteins, especially IDPs, can co-aggregate with α-synuclein in many pathological ailments. This article describes several such observations highlighting the role of heterotypic protein-protein interactions in the formation of hetero-amyloids. It is believed that the characterizations of molecular cross talks between amyloidogenic proteins as well as the mechanistic studies of heterotypic protein aggregation will allow us to decipher the role of the interacting proteins in amyloid proteomics.
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Affiliation(s)
- Karishma Bhasne
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab 140306, India.,Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab 140306, India
| | - Samrat Mukhopadhyay
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab 140306, India.,Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali, Mohali, Punjab 140306, India
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Sbrissa D, Naisan G, Ikonomov OC, Shisheva A. Apilimod, a candidate anticancer therapeutic, arrests not only PtdIns(3,5)P2 but also PtdIns5P synthesis by PIKfyve and induces bafilomycin A1-reversible aberrant endomembrane dilation. PLoS One 2018; 13:e0204532. [PMID: 30240452 PMCID: PMC6150535 DOI: 10.1371/journal.pone.0204532] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 09/10/2018] [Indexed: 01/02/2023] Open
Abstract
PIKfyve, an evolutionarily conserved kinase synthesizing PtdIns5P and PtdIns(3,5)P2, is crucial for mammalian cell proliferation and viability. Accordingly, PIKfyve inhibitors are now in clinical trials as anti-cancer drugs. Among those, apilimod is the most promising, yet its potency to inhibit PIKfyve and affect endomembrane homeostasis is only partially characterized. We demonstrate here for the first time that apilimod powerfully inhibited in vitro synthesis of PtdIns5P along with that of PtdIns(3,5)P2. HPLC-based resolution of intracellular phosphoinositides (PIs) revealed that apilimod triggered a marked reduction of both lipids in the context of intact cells. Notably, there was also a profound rise in PtdIns3P resulting from arrested PtdIns3P consumption for PtdIns(3,5)P2 synthesis. As typical for PIKfyve inhibition and the concomitant PtdIns(3,5)P2 reduction, apilimod induced the appearance of dilated endomembrane structures in the form of large translucent cytoplasmic vacuoles. Remarkably, bafilomycin A1 (BafA1) fully reversed the aberrant cell phenotype back to normal and completely precluded the appearance of cytoplasmic vacuoles when added prior to apilimod. Inspection of the PI profiles ruled out restoration of the reduced PtdIns(3,5)P2 pool as a molecular mechanism underlying BafA1 rescue. Rather, we found that BafA1 markedly attenuated the PtdIns3P elevation under PIKfyve inhibition. This was accompanied by profoundly decreased endosomal recruitment of fusogenic EEA1. Together, our data demonstrate that apilimod inhibits not only PtdIns(3,5)P2 but also PtdIns5P synthesis and that the cytoplasmic vacuolization triggered by the inhibitor is precluded or reversed by BafA1 through a mechanism associated, in part, with reduction in both PtdIns3P levels and EEA1 membrane recruitment.
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Affiliation(s)
- Diego Sbrissa
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Ghassan Naisan
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Ognian C. Ikonomov
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Assia Shisheva
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
- * E-mail:
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8
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Podinovskaia M, Spang A. The Endosomal Network: Mediators and Regulators of Endosome Maturation. ENDOCYTOSIS AND SIGNALING 2018; 57:1-38. [DOI: 10.1007/978-3-319-96704-2_1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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9
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Non-bilayer structures in mitochondrial membranes regulate ATP synthase activity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:586-599. [PMID: 29179995 DOI: 10.1016/j.bbamem.2017.11.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 10/26/2017] [Accepted: 11/22/2017] [Indexed: 01/12/2023]
Abstract
Cardiolipin (CL) is an anionic phospholipid at the inner mitochondrial membrane (IMM) that facilitates the formation of transient non-bilayer (non-lamellar) structures to maintain mitochondrial integrity. CL modulates mitochondrial functions including ATP synthesis. However, the biophysical mechanisms by which CL generates non-lamellar structures and the extent to which these structures contribute to ATP synthesis remain unknown. We hypothesized that CL and ATP synthase facilitate the formation of non-bilayer structures at the IMM to stimulate ATP synthesis. By using 1H NMR and 31P NMR techniques, we observed that increasing the temperature (8°C to 37°C), lowering the pH (3.0), or incubating intact mitochondria with CTII - an IMM-targeted toxin that increases the formation of immobilized non-bilayer structures - elevated the formation of non-bilayer structures to stimulate ATP synthesis. The F0 sector of the ATP synthase complex can facilitate the formation of non-bilayer structures as incubating model membranes enriched with IMM-specific phospholipids with exogenous DCCD-binding protein of the F0 sector (DCCD-BPF) elevated the formation of immobilized non-bilayer structures to a similar manner as CTII. Native PAGE assays revealed that CL, but not other anionic phospholipids, specifically binds to DCCD-BPF to promote the formation of stable lipid-protein complexes. Mechanistically, molecular docking studies identified two lipid binding sites for CL in DCCD-BPF. We propose a new model of ATP synthase regulation in which CL mediates the formation of non-bilayer structures that serve to cluster protons and ATP synthase complexes as a mechanism to enhance proton translocation to the F0 sector, and thereby increase ATP synthesis.
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Hyenne V, Labouesse M, Goetz JG. The Small GTPase Ral orchestrates MVB biogenesis and exosome secretion. Small GTPases 2016; 9:445-451. [PMID: 27875100 DOI: 10.1080/21541248.2016.1251378] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Extracellular vesicles are novel mediators of cell-cell communication. They are present in all species and involved in physiological and pathological processes. One class of extracellular vesicles, the exosomes, originate from an endosomal compartment, the MultiVesicular Body (MVB), and are released from the cell upon fusion of the MVB with the plasma membrane. Although different molecular mechanisms have been associated with MVB biogenesis and exosome secretion, how they coordinate remains poorly documented. We recently found that the small GTPase Ral contributes to exosome release in nematodes and mammalian tumor cells. More specifically, we found that C. elegans RAL-1 is required for the biogenesis of MVBs, and later for MVB fusion with the plasma membrane. Here, we discuss our results in relationship with other factors involved in extracellular vesicle production such as the ESCRT complex and Phospholipase 1D. We propose models to explain Ral function in exosome secretion, its conservation in animals, and its possible role in tumor progression.
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Affiliation(s)
- Vincent Hyenne
- a Inserm U1109 , MN3T , Strasbourg , France.,b Université de Strasbourg , Strasbourg , France.,c LabEx Medalis , Université de Strasbourg , Strasbourg , France.,d Fédération de Médecine Translationnelle de Strasbourg (FMTS) , Strasbourg , France.,e CNRS SNC5055 , Strasbourg , France
| | - Michel Labouesse
- f Sorbonne Universités , UPMC Univ Paris 06, UMR7622 - CNRS, Institut de Biologie Paris-Seine , Paris , France
| | - Jacky G Goetz
- a Inserm U1109 , MN3T , Strasbourg , France.,b Université de Strasbourg , Strasbourg , France.,c LabEx Medalis , Université de Strasbourg , Strasbourg , France.,d Fédération de Médecine Translationnelle de Strasbourg (FMTS) , Strasbourg , France
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Gilbert RJC. Protein-lipid interactions and non-lamellar lipidic structures in membrane pore formation and membrane fusion. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:487-99. [PMID: 26654785 DOI: 10.1016/j.bbamem.2015.11.026] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Revised: 10/23/2015] [Accepted: 11/30/2015] [Indexed: 12/27/2022]
Abstract
Pore-forming proteins and peptides act on their targeted lipid bilayer membranes to increase permeability. This approach to the modulation of biological function is relevant to a great number of living processes, including; infection, parasitism, immunity, apoptosis, development and neurodegeneration. While some pore-forming proteins/peptides assemble into rings of subunits to generate discrete, well-defined pore-forming structures, an increasing number is recognised to form pores via mechanisms which co-opt membrane lipids themselves. Among these, membrane attack complex-perforin/cholesterol-dependent cytolysin (MACPF/CDC) family proteins, Bax/colicin family proteins and actinoporins are especially prominent and among the mechanisms believed to apply are the formation of non-lamellar (semi-toroidal or toroidal) lipidic structures. In this review I focus on the ways in which lipids contribute to pore formation and contrast this with the ways in which lipids are co-opted also in membrane fusion and fission events. A variety of mechanisms for pore formation that involve lipids exists, but they consistently result in stable hybrid proteolipidic structures. These structures are stabilised by mechanisms in which pore-forming proteins modify the innate capacity of lipid membranes to respond to their environment, changing shape and/or phase and binding individual lipid molecules directly. In contrast, and despite the diversity in fusion protein types, mechanisms for membrane fusion are rather similar to each other, mapping out a pathway from pairs of separated compartments to fully confluent fused membranes. Fusion proteins generate metastable structures along the way which, like long-lived proteolipidic pore-forming complexes, rely on the basic physical properties of lipid bilayers. Membrane fission involves similar intermediates, in the reverse order. I conclude by considering the possibility that at least some pore-forming and fusion proteins are evolutionarily related homologues. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale.
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Affiliation(s)
- Robert J C Gilbert
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
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