Base de dados : MEDLINE
Pesquisa : D25.479.517.500 [Categoria DeCS]
Referências encontradas : 1526 [refinar]
Mostrando: 1 .. 10   no formato [Detalhado]

página 1 de 153 ir para página                         

  1 / 1526 MEDLINE  
              next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:29190425
[Au] Autor:Sebastian B; Favero T; Dittrich PS
[Ad] Endereço:Department of Biosystems Science and Engineering, ETH Zurich , Mattenstrasse 26, 4058 Basel, Switzerland.
[Ti] Título:The Effects of Shear Force Transmission Across Vesicle Membranes.
[So] Source:J Phys Chem Lett;8(24):6128-6134, 2017 Dec 21.
[Is] ISSN:1948-7185
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:We report a comprehensive study on mechanotransmission of shear forces across lipid bilayer membranes of giant unilamellar vesicles (GUVs). GUVs containing fluorescent tracer particles were immobilized on a microfluidic platform and exposed to shear flows. A method was developed for the visualization of three-dimensional flows at high precision by defocusing microscopy. We quantify the symmetry of external flow around the GUV and show its effects on vortex flows and luminal dynamics. With increasing asymmetry, luminal vortices merged while liquid exchange in between them increased. The effect of membrane composition was studied through addition of cholesterol. Mechanotransmission efficacy, quantified by the ratio of luminal flow to external flow, ranged from ε = 0.094 (0 mol % cholesterol) to ε = 0.043 (16 mol % cholesterol). Our findings give new cues to the mechanisms underlying the sensing of strength and spatial distribution of shear forces by cells and the impact of membrane composition.
[Mh] Termos MeSH primário: Bicamadas Lipídicas
Microscopia de Fluorescência
Modelos Biológicos
Lipossomas Unilamelares
[Mh] Termos MeSH secundário: Colesterol
Lipossomos
Membranas
Resistência ao Cisalhamento
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Lipid Bilayers); 0 (Liposomes); 0 (Unilamellar Liposomes); 97C5T2UQ7J (Cholesterol)
[Em] Mês de entrada:1802
[Cu] Atualização por classe:180205
[Lr] Data última revisão:
180205
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:171201
[St] Status:MEDLINE
[do] DOI:10.1021/acs.jpclett.7b02676


  2 / 1526 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28802697
[Au] Autor:Alvares DS; Wilke N; Ruggiero Neto J; Fanani ML
[Ad] Endereço:UNESP - São Paulo State University, IBILCE, Department of Physics, São José do Rio Preto, SP, Brazil.
[Ti] Título:The insertion of Polybia-MP1 peptide into phospholipid monolayers is regulated by its anionic nature and phase state.
[So] Source:Chem Phys Lipids;207(Pt A):38-48, 2017 Oct.
[Is] ISSN:1873-2941
[Cp] País de publicação:Ireland
[La] Idioma:eng
[Ab] Resumo:Polybia-MP1 or simply MP1 (IDWKKLLDAAKQIL-NH ) is a peptide with broad-spectrum bactericidal activity and a strong inhibitory effect against cancer cells. The aim of this work was to evaluate the effect of biophysical properties such as membrane texture and film thickness on MP1 interaction with neutral and anionic lipid membranes. For this purpose, we first explored the peptide's surface behavior. MP1 showed high surface activity, adsorbing onto bare air/aqueous interfaces up to higher surface pressures than the collapse pressure of MP1 Langmuir films. The MP1-lipid membrane interaction was studied using Langmuir phosphatidylcholine and phosphatidylserine (PS) monolayers as model membrane systems. PS was chosen since this negatively charged lipid was found predominantly on the outer leaflet of tumor cells, and it enhances MP1 activity for PS-containing membranes to a greater extent than for other negatively charged lipids. MP1 incorporated into anionic PS monolayers, which show a liquid-expanded (LE) phase or LE-liquid-condensed (LC) phase coexistence, up to lipid-packing densities higher than those of cell membranes. The mixed lipid/MP1 films were explored by Brewster angle microscopy and atomic force microscopy. MP1 partitioned preferentially into the LE phase state of PS films, and were thus excluded from the coexisting LC phase. This interaction had strong electrostatic bases: in pure water, the lipid-peptide interaction was strong enough to induce formation of reversible lipid-peptide 3D structures associated with the interface. MP1 incorporation into the LE phase was accompanied by a shift of the phase transition pressure to higher values and a thinning of the lipid film. These results showed a clear correlation between peptide penetration capacity and the presence or induction of the thin LE phase. This capacity to regulate membrane physical properties may be of relevance in the binding, incorporation and membrane selectivity of this promising antitumor peptide.
[Mh] Termos MeSH primário: Peptídeos Catiônicos Antimicrobianos/química
Peptídeos Catiônicos Antimicrobianos/metabolismo
Fosfolipídeos/química
Lipossomas Unilamelares/metabolismo
Venenos de Vespas/química
Venenos de Vespas/metabolismo
[Mh] Termos MeSH secundário: Ânions/química
Lipídeos de Membrana/química
Lipídeos de Membrana/metabolismo
Microscopia de Força Atômica
Concentração Osmolar
Propriedades de Superfície
Lipossomas Unilamelares/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Anions); 0 (Antimicrobial Cationic Peptides); 0 (Membrane Lipids); 0 (Phospholipids); 0 (Unilamellar Liposomes); 0 (Wasp Venoms); 0 (polybia-MPI, Polybia paulista)
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170925
[Lr] Data última revisão:
170925
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170814
[St] Status:MEDLINE


  3 / 1526 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28706229
[Au] Autor:Bleicken S; Hantusch A; Das KK; Frickey T; Garcia-Saez AJ
[Ad] Endereço:Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, 70569, Stuttgart, Germany.
[Ti] Título:Quantitative interactome of a membrane Bcl-2 network identifies a hierarchy of complexes for apoptosis regulation.
[So] Source:Nat Commun;8(1):73, 2017 07 13.
[Is] ISSN:2041-1723
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:The Bcl-2 proteins form a complex interaction network that controls mitochondrial permeabilization and apoptosis. The relative importance of different Bcl-2 complexes and their spatio-temporal regulation is debated. Using fluorescence cross-correlation spectroscopy to quantify the interactions within a minimal Bcl-2 network, comprised by cBid, Bax, and Bcl-xL, we show that membrane insertion drastically alters the pattern of Bcl-2 complexes, and that the C-terminal helix of Bcl-xL determines its binding preferences. At physiological temperature, Bax can spontaneously activate in a self-amplifying process. Strikingly, Bax also recruits Bcl-xL to membranes, which is sufficient to retrotranslocate Bax back into solution to secure membrane integrity. Our study disentangles the hierarchy of Bcl-2 complex formation in relation to their environment: Bcl-xL association with cBid occurs in solution and in membranes, where the complex is stabilized, whereas Bcl-xL binding to Bax occurs only in membranes and with lower affinity than to cBid, leading instead to Bax retrotranslocation.The permeabilization of the mitochondrial outer membrane to induce apoptosis is regulated by complex interactions between Bcl-2 family members. Here the authors develop a quantitative interactome of a membrane Bcl-2 network and identify a hierarchy of protein complexes in apoptosis induction.
[Mh] Termos MeSH primário: Proteína X Associada a bcl-2/química
Proteína X Associada a bcl-2/metabolismo
[Mh] Termos MeSH secundário: Animais
Apoptose
Membrana Celular
Seres Humanos
Camundongos
Modelos Químicos
Ligação Proteica
Lipossomas Unilamelares/química
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Unilamellar Liposomes); 0 (bcl-2-Associated X Protein)
[Em] Mês de entrada:1711
[Cu] Atualização por classe:171107
[Lr] Data última revisão:
171107
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170715
[St] Status:MEDLINE
[do] DOI:10.1038/s41467-017-00086-6


  4 / 1526 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28703789
[Au] Autor:Bhatia T; Cornelius F; Ipsen JH
[Ad] Endereço:MEMPHYS Center for Biomembrane Physics and Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, Odense, Denmark.
[Ti] Título:Capturing suboptical dynamic structures in lipid bilayer patches formed from free-standing giant unilamellar vesicles.
[So] Source:Nat Protoc;12(8):1563-1575, 2017 Aug.
[Is] ISSN:1750-2799
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:There is accumulating evidence that the small-scale lateral organization of biological membranes has a crucial role in signaling and trafficking in cells. However, it has been difficult to characterize these features with existing methods for preparing and analyzing freestanding membranes, because the dynamics occurs below the optical resolution possible with these protocols. We have developed a protocol that permits the imaging of lipid nanodomains and lateral protein organization in membranes of giant unilamellar vesicles (GUVs). Freestanding GUVs are transferred onto a mica support, and after treatment with magnesium chloride, they collapse to form planar lipid bilayer (PLB) patches. Rapid GUV collapse onto the mica preserves the lateral organization of freestanding membranes and thus makes it possible to image 'snapshots' of GUVs up to nanometer resolution by high-resolution microscopy. The method has been applied to classical lipid raft mixtures in which suboptical domain fluctuations have been imaged in both the liquid-ordered and liquid-disordered membrane phases. High-resolution scanning by atomic force microscopy (AFM) of membranes composed of binary and ternary lipid mixtures reconstituted with Na /K -ATPase (NKA) has revealed the spatial distribution and orientations of individual proteins, as well as details of membrane lateral structure. Immunolabeling followed by confocal microscopy can also provide information about the spatial distribution of proteins. The protocol opens up a new avenue for quantitative biophysical studies of suboptical dynamic structures in biomembranes, which are local and short-lived. Preparation of GUVs, PLB patches and their imaging takes <24 h.
[Mh] Termos MeSH primário: Bicamadas Lipídicas/química
Bicamadas Lipídicas/metabolismo
Lipossomas Unilamelares/química
Lipossomas Unilamelares/metabolismo
[Mh] Termos MeSH secundário: Fenômenos Biofísicos
Microscopia
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Lipid Bilayers); 0 (Unilamellar Liposomes)
[Em] Mês de entrada:1707
[Cu] Atualização por classe:170726
[Lr] Data última revisão:
170726
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170714
[St] Status:MEDLINE
[do] DOI:10.1038/nprot.2017.047


  5 / 1526 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28700928
[Au] Autor:Lee MT; Hung WC; Hsieh MH; Chen H; Chang YY; Huang HW
[Ad] Endereço:National Synchrotron Radiation Research Center, Hsinchu, Taiwan; Department of Physics, National Central University, Jhongli, Taiwan.
[Ti] Título:Molecular State of the Membrane-Active Antibiotic Daptomycin.
[So] Source:Biophys J;113(1):82-90, 2017 Jul 11.
[Is] ISSN:1542-0086
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Membrane-active antibiotics are potential alternatives to the resistance-prone conventional antibiotics. Daptomycin, a cyclic lipopeptide, is the only membrane-active antibiotic approved by the U.S. Food and Drug Administration so far. The drug interacts with the cytoplasmic membranes of Gram-positive pathogens, causing membrane permeabilization to ions and cell death. The antibiotic activity is calcium-ion dependent and correlates with the target membrane's content of phosphatidylglycerol (PG). For such a complex reaction with membranes, it has been difficult to uncover the molecular process that underlies its antibacterial activity. The role of the cofactor, calcium ions, has been confusing. Many have proposed that calcium ions binding to daptomycin is a precondition for membrane interaction. Here, we report our findings on the molecular state of daptomycin before and after its membrane-binding reaction, particularly at therapeutic concentrations in the low micromolar range. We were able to perform small-angle x-ray scattering at sufficiently low daptomycin concentrations to determine that the molecules are monomeric before membrane binding. By careful circular dichroism (CD) analyses of daptomycin with Ca and PG-containing membranes, we found that there are only two states identifiable by CD, one before and another after membrane binding; all other CD spectra are linear combinations of the two. Before membrane binding, the molecular state of daptomycin as defined by CD is the same with or without calcium ions. We are able to determine the stoichiometric ratios of the membrane-binding reaction. The stoichiometric ratio of daptomycin to calcium is 2:3. The stoichiometric ratio of daptomycin to PG is ∼1:1 if only the PG lipids in the outer leaflets of membranes are accessible to daptomycin.
[Mh] Termos MeSH primário: Antibacterianos/química
Daptomicina/química
[Mh] Termos MeSH secundário: Antibacterianos/farmacologia
Cálcio/química
Cátions Bivalentes/química
Dicroísmo Circular
Daptomicina/farmacologia
Modelos Moleculares
Fosfatidilcolinas/química
Fosfatidilgliceróis/química
Espalhamento a Baixo Ângulo
Lipossomas Unilamelares/química
Difração de Raios X
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Anti-Bacterial Agents); 0 (Cations, Divalent); 0 (Phosphatidylcholines); 0 (Phosphatidylglycerols); 0 (Unilamellar Liposomes); 66322-31-4 (1,2-dioleoyl-sn-glycero-3-phosphoglycerol); EDS2L3ODLV (1,2-oleoylphosphatidylcholine); NWQ5N31VKK (Daptomycin); SY7Q814VUP (Calcium)
[Em] Mês de entrada:1708
[Cu] Atualização por classe:171116
[Lr] Data última revisão:
171116
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170713
[St] Status:MEDLINE


  6 / 1526 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28700922
[Au] Autor:Soria MA; Cervantes SA; Bajakian TH; Siemer AB
[Ad] Endereço:Department of Biochemistry and Molecular Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California.
[Ti] Título:The Functional Amyloid Orb2A Binds to Lipid Membranes.
[So] Source:Biophys J;113(1):37-47, 2017 Jul 11.
[Is] ISSN:1542-0086
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Lipid membranes interact with and influence the aggregation of many amyloid-forming proteins. Orb2 is a cytoplasmic polyadenylation element-binding protein homolog in Drosophila melanogaster that forms functional amyloids necessary for long-term memory. One isoform, Orb2A, has a unique N-terminus that has been shown to be important for the formation of amyloid-like aggregates and long-term memory in vivo. Orb2A is also found enriched in the synaptic membrane fraction. Our sequence and hydropathy analysis suggests that it can form an amphipathic helix, which is ideal for lipid membrane interaction. We used circular dichroism and site-directed spin labeling coupled with electron paramagnetic resonance to test the first 88 amino acids of Orb2A for lipid interaction. We show that Orb2A1-88 interacts with anionic lipid membranes using an amphipathic helix at its unique N-terminus. This interaction depends on the charge of the lipid membrane and the degree of membrane curvature. We used transmission electron microscopy and electron paramagnetic resonance to show that the presence of anionic small unilamellar vesicles inhibits amyloid fibril formation by Orb2A. This inhibition by anionic membranes could be a potential mechanism regulating Orb2A amyloid formation in vivo.
[Mh] Termos MeSH primário: Amiloide/metabolismo
Proteínas de Drosophila/metabolismo
Fosfatidilcolinas/química
Fosfatidilgliceróis/química
Fosfatidilserinas/química
Fatores de Transcrição/metabolismo
Lipossomas Unilamelares/química
Fatores de Poliadenilação e Clivagem de mRNA/metabolismo
[Mh] Termos MeSH secundário: Sequência de Aminoácidos
Amiloide/química
Animais
Sítios de Ligação
Dicroísmo Circular
Proteínas de Drosophila/química
Proteínas de Drosophila/genética
Drosophila melanogaster
Espectroscopia de Ressonância de Spin Eletrônica
Escherichia coli
Microscopia Eletrônica de Transmissão
Isoformas de Proteínas/química
Isoformas de Proteínas/genética
Isoformas de Proteínas/metabolismo
Estrutura Secundária de Proteína
Propriedades de Superfície
Fatores de Transcrição/química
Fatores de Transcrição/genética
Fatores de Poliadenilação e Clivagem de mRNA/química
Fatores de Poliadenilação e Clivagem de mRNA/genética
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Amyloid); 0 (CPEB1 protein, Drosophila); 0 (Drosophila Proteins); 0 (Phosphatidylcholines); 0 (Phosphatidylglycerols); 0 (Phosphatidylserines); 0 (Protein Isoforms); 0 (Transcription Factors); 0 (Unilamellar Liposomes); 0 (mRNA Cleavage and Polyadenylation Factors); 40290-44-6 (1-palmitoyl-2-oleoylglycero-3-phosphoserine); 81490-05-3 (1-palmitoyl-2-oleoylglycero-3-phosphoglycerol); TE895536Y5 (1-palmitoyl-2-oleoylphosphatidylcholine)
[Em] Mês de entrada:1708
[Cu] Atualização por classe:170825
[Lr] Data última revisão:
170825
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170713
[St] Status:MEDLINE


  7 / 1526 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28684088
[Au] Autor:Do TTT; Dao UPN; Bui HT; Nguyen TT
[Ad] Endereço:School of Biotechnology, International University, Vietnam National University in HCMC, Block 6, Linh Trung Ward, Thu Duc District, Ho Chi Minh City, Viet Nam.
[Ti] Título:Effect of electrostatic interaction between fluoxetine and lipid membranes on the partitioning of fluoxetine investigated using second derivative spectrophotometry and FTIR.
[So] Source:Chem Phys Lipids;207(Pt A):10-23, 2017 Oct.
[Is] ISSN:1873-2941
[Cp] País de publicação:Ireland
[La] Idioma:eng
[Ab] Resumo:The interaction between a drug molecule and lipid bilayers is highly important regarding the pharmaceutical activity of the drug. In this study, the interaction of fluoxetine, a well-known selective serotonin reuptake inhibitor antidepressant and lipid bilayers composed of 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DPPG) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) was studied from the aspect of electrostatics using second derivative spectrophotometry and Fourier transform infrared spectroscopy (FTIR) in order to provide insights into the drug behavior. Changing pH from 7.4 to 9.5 to increases the neutral state of fluoxetine, the partitioning of fluoxetine into the zwitterionic DPPC large unilamellar vesicles (LUVs) was increased whereas it was reduced into the negatively charged DPPG LUVs. Fluoxetine was found to exhibit a disordering effect on the acyl chains of DPPC and DPPG bilayers upon its partitioning. In addition, increasing concentration of NaCl lessened the binding of fluoxetine into DPPG bilayers due to the reduction in electrostatic attraction between positively charged fluoxetine and negatively charged DPPG LUVs. In addition, the FTIR study revealed that increasing the NaCl concentration could trigger the shift to higher frequency of the CH stretching as well as the notable blue shift in the PO regions of DPPG, indicating that fluoxetine had deeper penetration into DPPG LUVs. The differences in the NaCl concentration showed a negligible effect on the incorporation of fluoxetine into the zwitterionic DPPC LUVs. In summary, the electrostatic interaction plays an important role on the partitioning of a cationic amphiphilic SSIR drug into the lipid bilayers and the drug partitioning induces the lipids' conformational change. These imply a possible influence on the drug pharmacology.
[Mh] Termos MeSH primário: Fluoxetina/química
Bicamadas Lipídicas/química
[Mh] Termos MeSH secundário: 1,2-Dipalmitoilfosfatidilcolina/análogos & derivados
1,2-Dipalmitoilfosfatidilcolina/química
Fluoxetina/metabolismo
Concentração de Íons de Hidrogênio
Cinética
Bicamadas Lipídicas/metabolismo
Fosfatidilgliceróis/química
Cloreto de Sódio/química
Espectrofotometria Ultravioleta
Espectroscopia de Infravermelho com Transformada de Fourier
Eletricidade Estática
Lipossomas Unilamelares/química
Lipossomas Unilamelares/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Lipid Bilayers); 0 (Phosphatidylglycerols); 0 (Unilamellar Liposomes); 01K63SUP8D (Fluoxetine); 2644-64-6 (1,2-Dipalmitoylphosphatidylcholine); 319X2NFW0A (colfosceril palmitate); 451W47IQ8X (Sodium Chloride); VA9U6BR3SB (1,2-dipalmitoylphosphatidylglycerol)
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170925
[Lr] Data última revisão:
170925
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170708
[St] Status:MEDLINE


  8 / 1526 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28591609
[Au] Autor:Jiang Y; Pryse KM; Melnykov A; Genin GM; Elson EL
[Ad] Endereço:Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri.
[Ti] Título:Investigation of Nanoscopic Phase Separations in Lipid Membranes Using Inverse FCS.
[So] Source:Biophys J;112(11):2367-2376, 2017 Jun 06.
[Is] ISSN:1542-0086
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Measurement of the sizes of nanoscopic particles is a difficult challenge, especially in two-dimensional systems such as cell membranes. We have extended inverse fluorescence correlation spectroscopy (iFCS) to endow it with unique advantages for measuring particle size from the nano- to the microscale. We have augmented iFCS with an analysis of moments of fluorescence fluctuations and used it to measure stages of phase separation in model lipid bilayer membranes. We observed two different pathways for the growth of phase domains. In one, nanoscopic gel domains appeared first and then gradually grew to micrometer size. In the other, the domains reached micrometer size quickly, and their number gradually increased. These measurements demonstrate the value of iFCS measurements through their ability, to our knowledge, to provide new information about the mechanism of lipid phase separation and potentially about the physical basis of naturally occurring nanodomains such as lipid rafts.
[Mh] Termos MeSH primário: Bicamadas Lipídicas/química
Microdomínios da Membrana/química
Nanoestruturas/química
Espectrometria de Fluorescência
Lipossomas Unilamelares/química
[Mh] Termos MeSH secundário: Calibragem
Difusão
Cinética
Microscopia de Fluorescência
Fótons
Espectrometria de Fluorescência/métodos
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Lipid Bilayers); 0 (Unilamellar Liposomes)
[Em] Mês de entrada:1708
[Cu] Atualização por classe:170814
[Lr] Data última revisão:
170814
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170608
[St] Status:MEDLINE


  9 / 1526 MEDLINE  
              first record previous record next record last record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28591607
[Au] Autor:Kuhlmann JW; Junius M; Diederichsen U; Steinem C
[Ad] Endereço:Institute of Organic and Biomolecular Chemistry, University of Göttingen, Göttingen, Germany.
[Ti] Título:SNARE-Mediated Single-Vesicle Fusion Events with Supported and Freestanding Lipid Membranes.
[So] Source:Biophys J;112(11):2348-2356, 2017 Jun 06.
[Is] ISSN:1542-0086
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:In vitro single-vesicle fusion assays are important tools to analyze the details of SNARE-mediated fusion processes. In this study, we employed planar pore-spanning membranes (PSMs) prepared on porous silicon substrates with large pore diameters of 5 µm, allowing us to compare the process of vesicle docking and fusion on the supported parts of the PSMs (s-PSMs) with that on the freestanding membrane parts (f-PSM) under the exact same experimental conditions. The PSMs harbor the t-SNARE ΔN49-complex to investigate the dynamics and fusogenicity of single large unilamellar vesicles doped with the v-SNARE synaptobrevin 2 by means of spinning-disc confocal microscopy with a time resolution of 10 ms. Our results demonstrate that vesicles docked to the s-PSM were fully immobile, whereas those docked to the f-PSM were mobile with a mean diffusion coefficient of 0.42 µm /s. Despite the different dynamics of the vesicles on the two membrane types, similar fusion kinetics were observed, giving rise to a common fusion mechanism. Further investigations of individual lipid mixing events on the s-PSMs revealed semi-stable post-fusion structures.
[Mh] Termos MeSH primário: Fusão de Membrana/fisiologia
Proteínas SNARE/metabolismo
Lipossomas Unilamelares/metabolismo
[Mh] Termos MeSH secundário: Animais
Difusão
Escherichia coli
Cinética
Bicamadas Lipídicas/química
Microscopia Confocal
Microscopia de Fluorescência
Porosidade
Ratos
Proteínas SNARE/química
Compostos de Silício
Dióxido de Silício
Lipossomas Unilamelares/química
Proteína 2 Associada à Membrana da Vesícula/química
Proteína 2 Associada à Membrana da Vesícula/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Lipid Bilayers); 0 (SNARE Proteins); 0 (Silicon Compounds); 0 (Unilamellar Liposomes); 0 (Vesicle-Associated Membrane Protein 2); 12033-89-5 (silicon nitride); 7631-86-9 (Silicon Dioxide)
[Em] Mês de entrada:1708
[Cu] Atualização por classe:170814
[Lr] Data última revisão:
170814
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170608
[St] Status:MEDLINE


  10 / 1526 MEDLINE  
              first record previous record
seleciona
para imprimir
Fotocópia
Texto completo
[PMID]:28538152
[Au] Autor:Dingeldein APG; Pokorná S; Lidman M; Sparrman T; Sachl R; Hof M; Gröbner G
[Ad] Endereço:Department of Chemistry, Umeå University, Umeå, Sweden.
[Ti] Título:Apoptotic Bax at Oxidatively Stressed Mitochondrial Membranes: Lipid Dynamics and Permeabilization.
[So] Source:Biophys J;112(10):2147-2158, 2017 May 23.
[Is] ISSN:1542-0086
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Mitochondria are crucial compartments of eukaryotic cells because they function as the cellular power plant and play a central role in the early stages of programmed cell death (apoptosis). To avoid undesired cell death, this apoptotic pathway is tightly regulated by members of the Bcl-2 protein family, which interact on the external surface of the mitochondria, i.e., the mitochondrial outer membrane (MOM), and modulate its permeability to apoptotic factors, controlling their release into the cytosol. A growing body of evidence suggests that the MOM lipids play active roles in this permeabilization process. In particular, oxidized phospholipids (OxPls) formed under intracellular stress seem to directly induce apoptotic activity at the MOM. Here we show that the process of MOM pore formation is sensitive to the type of OxPls species that are generated. We created MOM-mimicking liposome systems, which resemble the cellular situation before apoptosis and upon triggering of oxidative stress conditions. These vesicles were studied using P solid-state magic-angle-spinning nuclear magnetic resonance spectroscopy and differential scanning calorimetry, together with dye leakage assays. Direct polarization and cross-polarization nuclear magnetic resonance experiments enabled us to probe the heterogeneity of these membranes and their associated molecular dynamics. The addition of apoptotic Bax protein to OxPls-containing vesicles drastically changed the membranes' dynamic behavior, almost completely negating the previously observed effect of temperature on the lipids' molecular dynamics and inducing an ordering effect that led to more cooperative membrane melting. Our results support the hypothesis that the mitochondrion-specific lipid cardiolipin functions as a first contact site for Bax during its translocation to the MOM in the onset of apoptosis. In addition, dye leakage assays revealed that different OxPls species in the MOM-mimicking vesicles can have opposing effects on Bax pore formation.
[Mh] Termos MeSH primário: Apoptose/fisiologia
Mitocôndrias/metabolismo
Membranas Mitocondriais/metabolismo
Proteína X Associada a bcl-2/metabolismo
[Mh] Termos MeSH secundário: Varredura Diferencial de Calorimetria
Cardiolipinas/metabolismo
Permeabilidade da Membrana Celular
Escherichia coli
Corantes Fluorescentes
Seres Humanos
Bicamadas Lipídicas/química
Ressonância Magnética Nuclear Biomolecular
Oxirredução
Estresse Oxidativo/fisiologia
Fosfolipídeos/metabolismo
Temperatura Ambiente
Lipossomas Unilamelares/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (BAX protein, human); 0 (Cardiolipins); 0 (Fluorescent Dyes); 0 (Lipid Bilayers); 0 (Phospholipids); 0 (Unilamellar Liposomes); 0 (bcl-2-Associated X Protein)
[Em] Mês de entrada:1708
[Cu] Atualização por classe:170809
[Lr] Data última revisão:
170809
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170525
[St] Status:MEDLINE



página 1 de 153 ir para página                         
   


Refinar a pesquisa
  Base de dados : MEDLINE Formulário avançado   

    Pesquisar no campo  
1  
2
3
 
           



Search engine: iAH v2.6 powered by WWWISIS

BIREME/OPAS/OMS - Centro Latino-Americano e do Caribe de Informação em Ciências da Saúde