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Lipid rafts

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https://www.readbyqxmd.com/read/29166667/flotillin-scaffold-activity-contributes-to-type-vii-secretion-system-assembly-in-staphylococcus-aureus
#1
Benjamin Mielich-Süss, Rabea M Wagner, Nicole Mietrach, Tobias Hertlein, Gabriella Marincola, Knut Ohlsen, Sebastian Geibel, Daniel Lopez
Scaffold proteins are ubiquitous chaperones that promote efficient interactions between partners of multi-enzymatic protein complexes; although they are well studied in eukaryotes, their role in prokaryotic systems is poorly understood. Bacterial membranes have functional membrane microdomains (FMM), a structure homologous to eukaryotic lipid rafts. Similar to their eukaryotic counterparts, bacterial FMM harbor a scaffold protein termed flotillin that is thought to promote interactions between proteins spatially confined to the FMM...
November 22, 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/29163910/cholesterol-directed-nanoparticle-assemblies-based-on-single-amino-acid-peptide-mutations-activate-cellular-uptake-and-decrease-tumor-volume
#2
Shang Li, Rongfeng Zou, Yaoquan Tu, Junchen Wu, Markita P Landry
Peptide drugs have been difficult to translate into effective therapies due to their low in vivo stability. Here, we report a strategy to develop peptide-based therapeutic nanoparticles by screening a peptide library differing by single-site amino acid mutations of lysine-modified cholesterol. Certain cholesterol-modified peptides are found to promote and stabilize peptide α-helix formation, resulting in selectively cell-permeable peptides. One cholesterol-modified peptide self-assembles into stable nanoparticles with considerable α-helix propensity stabilized by intermolecular van der Waals interactions between inter-peptide cholesterol molecules, and shows 68...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29163167/experimental-evaluation-of-the-transport-mechanisms-of-poifn-%C3%AE-in-caco-2-cells
#3
Xin Liu, Sidi Zheng, Yue Qin, Wenya Ding, Yabin Tu, Xingru Chen, Yunzhou Wu, Li Yanhua, Xuehui Cai
For the development of an efficient intestinal delivery system for Porcine interferon-α (PoIFN-α), the understanding of transport mechanisms of which in the intestinal cell is essential. In this study, we investigated the absorption mechanisms of PoIFN-α in intestine cells. Caco-2 cells and fluorescein isothiocyanate-labeled (FITC)-PoIFN-α were used to explore the whole transport process, including endocytosis, intracellular trafficking, exocytosis, and transcytosis. Via various techniques, the transport pathways of PoIFN-α in Caco-2 cells and the mechanisms were clarified...
2017: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/29162448/intracellular-cholesterol-level-regulates-sensitivity-of-glioblastoma-cells-against-temozolomide-induced-cell-death-by-modulation-of-caspase-8-activation-via-death-receptor-5-accumulation-and-activation-in-the-plasma-membrane-lipid-raft
#4
Yutaro Yamamoto, Arata Tomiyama, Nobuyoshi Sasaki, Hideki Yamaguchi, Takuya Shirakihara, Katsuhiko Nakashima, Kosuke Kumagai, Satoru Takeuchi, Terushige Toyooka, Kojiro Wada, Yoshitaka Narita, Koichi Ichimura, Ryuichi Sakai, Hiroki Namba, Kentaro Mori
Development of resistance against temozolomide (TMZ) in glioblastoma (GBM) after continuous treatment with TMZ is one of the critical problems in clinical GBM therapy. Intracellular cholesterol regulates cancer cell biology, but whether intracellular cholesterol is involved in TMZ resistance of GBM cells remains unclear. The involvement of intracellular cholesterol in acquired resistance against TMZ in GBM cells was investigated. Intracellular cholesterol levels were measured in human U251 MG cells with acquired TMZ resistance (U251-R cells) and TMZ-sensitive control U251 MG cells (U251-Con cells), and found that the intracellular cholesterol level was significantly lower in U251-R cells than in U251-Con cells...
November 18, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/29158160/glycoprotein-m6a-as-a-signaling-transducer-in-neuronal-lipid-rafts
#5
Yasuyuki Ito, Atsuko Honda, Michihiro Igarashi
Neuronal development is composed of the complex steps which involve many signaling proteins. On the other hand, there are many proteins highly expressed in the differentiated neurons at developmental stages, but of which physiological functions are not precisely known so far. Glycoprotein 6a (GPM6a) currently belongs to such proteins. This protein has four-transmembrane domains and is a member of proteolipid protein family. Recently, we demonstrated that GPM6a is highly concentrated in lipid rafts of the developing neuron with its palmitoylation, and that this molecule is involved in rapid determination of the neuronal polarity, in response to laminin, an extracellular matrix protein (Honda et al...
November 17, 2017: Neuroscience Research
https://www.readbyqxmd.com/read/29155700/phase-behavior-of-charged-vesicles-under-symmetric-and-asymmetric-solution-conditions-monitored-with-fluorescence-microscopy
#6
Bastian Kubsch, Tom Robinson, Jan Steinkühler, Rumiana Dimova
Phase-separated giant unilamellar vesicles (GUVs) exhibiting coexisting liquid-ordered and liquid-disordered domains are a common biophysical tool to investigate the lipid raft hypothesis. Numerous studies, however, neglect the impact of physiological solution conditions. On that account, the current work presents the effect of high-salinity buffer and trans-membrane solution asymmetry on liquid-liquid phase separation in charged GUVs grown from dioleylphosphatidylglycerol, egg sphingomyelin, and cholesterol...
October 24, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/29155215/membrane-estrogen-receptors-signal-to-determine-transcription-factor-function
#7
Ellis R Levin
Estrogen receptors (ER) alpha and beta as well as many other steroid receptors are found both within the nucleus and outside the nucleus. This includes extra-nuclear receptors in many organelles, including mitochondria, endoplasmic reticulum, cytosolic endosomes, and membrane lipid rafts, such as caveolae. The functions of these receptors in the various extra-nuclear cell organelles are not well described, but progress for understanding steroid receptor signaling from the membrane has advanced. In this Review I will discuss the enlarging role of membrane ER signaling to the expression, cell localization, and function of transcription factors that are essential to mediate cell physiology or pathophysiology in many organs...
November 16, 2017: Steroids
https://www.readbyqxmd.com/read/29154925/membrane-cholesterol-depletion-in-cortical-neurons-highlights-altered-nmda-receptor-functionality-in-a-mouse-model-of-amyotrophic-lateral-sclerosis
#8
Alessia Antonini, Silvia Caioli, Luana Saba, Giulia Vindigni, Silvia Biocca, Nadia Canu, Cristina Zona
Amyotrophic Lateral Sclerosis (ALS) is a chronic neurodegenerative disease affecting upper and lower motor neurons, with unknown aetiology. Lipid rafts, cholesterol enriched microdomains of the plasma membrane, have been linked to neurodegenerative disorders like ALS. The NMDA-receptor subcellular localization in lipid rafts is known to play many roles, from modulating memory strength to neurotoxicity. In this study, performed on the widely used G93A mouse model of ALS, we have shown an equal content of total membrane cholesterol in Control and G93A cortical cultures...
November 14, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/29145158/vibrio-cholerae-ompu-induces-il-8-expression-in-human-intestinal-epithelial-cells
#9
Jae Seung Yang, Jun Ho Jeon, Mi Seon Jang, Seok-Seong Kang, Ki Bum Ahn, Manki Song, Cheol-Heui Yun, Seung Hyun Han
Although Vibrio cholerae colonizes the small intestine and induces acute inflammatory responses, less is known about the molecular mechanisms of V. cholerae-induced inflammatory responses in the intestine. We recently reported that OmpU, one of the most abundant outer membrane proteins of V. cholerae, plays an important role in the innate immunity of the whole bacteria. In this study, we evaluated the role of OmpU in induction of IL-8, a representative chemokine that recruits various inflammatory immune cells, in the human intestinal epithelial cell (IEC) line, HT-29...
November 13, 2017: Molecular Immunology
https://www.readbyqxmd.com/read/29142315/hiv-1-counteracts-an-innate-restriction-by-amyloid-precursor-protein-resulting-in-neurodegeneration
#10
Qingqing Chai, Vladimir Jovasevic, Viacheslav Malikov, Yosef Sabo, Scott Morham, Derek Walsh, Mojgan H Naghavi
While beta-amyloid (Aβ), a classic hallmark of Alzheimer's disease (AD) and dementia, has long been known to be elevated in the human immunodeficiency virus type 1 (HIV-1)-infected brain, why and how Aβ is produced, along with its contribution to HIV-associated neurocognitive disorder (HAND) remains ill-defined. Here, we reveal that the membrane-associated amyloid precursor protein (APP) is highly expressed in macrophages and microglia, and acts as an innate restriction against HIV-1. APP binds the HIV-1 Gag polyprotein, retains it in lipid rafts and blocks HIV-1 virion production and spread...
November 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/29137913/neutrophil-cd16b-crosslinking-induces-lipid-raft-mediated-activation-of-shp-2-and-affects-cytokine-expression-and-retarded-neutrophil-apoptosis
#11
H Yang, H Jiang, Y Song, D J Chen, X J Shen, J H Chen
Two different types of FcRs for IgG are constitutively expressed on the surface of human neutrophils, namely, FcγRIIA (CD32a) and FcγRIIIB (CD16b). Unlike FcγRIIA, FcγRIIIb is GPI anchored to the cell membrane and its signal transduction is still ambiguous. To further understand the signal transduction of CD16b, we compared neutrophil cytokine expression and apoptosis by the cross-linking of CD32a and CD16b respectively. We found that both CD32a and CD16b crosslinking can activate neutrophils, but did not exactly share cytokine expression profiles...
November 11, 2017: Experimental Cell Research
https://www.readbyqxmd.com/read/29132227/oxidative-stress-in-hiv-infection-and-alcohol-use-role-of-redox-signals-in-modulation-of-lipid-rafts-and-abc-transporters
#12
Samikkannu Thangavel, Carmen T Mulet, Venkata S R Atluri, Marisela Agudelo, Rhonda Rosenberg, Jessy G Devieux, Madhavan P N Nair
AIMS: HIV infection induces oxidative stress and alcohol use accelerates disease progression subsequently causing immune dysfunction. However, HIV and alcohol impact on lipid rafts-mediated immune dysfunction remains unknown. In this study, we investigate the modulation by which oxidative stress induces reactive oxygen species (ROS) affecting redox expression, lipid rafts caveiloin-1, ATP-binding cassette (ABC)-transporters, and transcriptional SREBP gene and protein modification and how these mechanisms are associated with arachidonic acid (AA) metabolites in HIV positive alcohol users, and how they escalate immune dysfunction...
November 13, 2017: Antioxidants & Redox Signaling
https://www.readbyqxmd.com/read/29131610/real-time-imaging-of-single-molecule-enzyme-cascade-using-a-dna-origami-raft
#13
Lele Sun, Yanjing Gao, Yan Xu, Jie Chao, Huajie Liu, Lianhui Wang, Di Li, Chunhai Fan
The dynamics of enzymes are directly associated with their functions in various biological processes. Nevertheless, the ability to image motions of single enzymes in a highly parallel fashion remains a challenge. Here, we develop a DNA origami raft-based platform for in-situ real-time imaging of enzyme cascade at the single-molecule level. The motions of enzymes are rationally controlled via different tethering modes on a two-dimensional (2D) supported lipid bilayer (SLB). We construct an enzyme cascade by anchoring catalase on cholesterol-labeled double stranded (ds) DNA, and glucose oxidase on cholesterol-labeled origami rafts...
November 13, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29129657/transport-mechanism-of-lipid-covered-saquinavir-pure-drug-nanoparticles-in-intestinal-epithelium
#14
Dengning Xia, Yuan He, Qiuxia Li, Cunde Hu, Wei Huang, Yunhai Zhang, Feng Wan, Chi Wang, Yong Gan
Pure drug nanoparticles (NPs) represent a promising formulation for improved drug solubility and controlled dissolution velocity. However, limited absorption by the intestinal epithelium remains challenge to their clinical application, and little is known about how these NPs within the cells are transported. To improve cellular uptake and transport of pure nanodrug in cells, here, a lipid covered saquinavir (SQV) pure drug NP (Lipo@nanodrug) was designed by modifying a pure SQV NP (nanodrug) with a phospholipid bilayer...
November 10, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
https://www.readbyqxmd.com/read/29126773/clomipramine-counteracts-lipid-raft-disturbance-due-to-short-term-muscle-disuse
#15
Irina G Bryndina, Maria N Shalagina, Alexey V Sekunov, Andrei L Zefirov, Alexey M Petrov
Disuse-induced skeletal muscle dysfunction is a serious consequence of long-term spaceflight, numerous diseases and conditions for which treatment possibilities are still strictly limited. We have previously shown that acute hindlimb suspension (HS)-mediated disuse disrupts membrane lipid rafts in the unloaded muscle. Here, we investigated whether pretreatment of rats with the inhibitor of acid sphingomyelinase, clomipramine (1.25mg/g/day, intramuscularly, for 5days before HS), is able to hinder the loss in lipid raft integrity in response to 12h of HS...
November 7, 2017: Neuroscience Letters
https://www.readbyqxmd.com/read/29118431/mechanotransduction-of-matrix-stiffness-in-regulation-of-focal-adhesion-size-and-number-reciprocal-regulation-of-caveolin-1-and-%C3%AE-1-integrin
#16
Yi-Chun Yeh, Jin-Ying Ling, Wan-Chun Chen, Hsi-Hui Lin, Ming-Jer Tang
Focal adhesion (FA) assembly, mediated by integrin activation, responds to matrix stiffness; however, the underlying mechanisms are unclear. Here, we showed that β1 integrin and caveolin-1 (Cav1) levels were decreased with declining matrix stiffness. Soft matrix selectively downregulated β1 integrin by endocytosis and subsequent lysosomal degradation. Disruption of lipid rafts with methyl-β-cyclodextrin or nystatin, or knockdown of Cav1 by siRNA decreased cell spreading, FA assembly, and β1 integrin protein levels in cells cultured on stiff matrix...
November 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29118375/the-lipid-raft-dwelling-protein-us9-can-be-manipulated-to-target-app-compartmentalization-app-processing-and-neurodegenerative-disease-pathogenesis
#17
Renato Brandimarti, Gordon S Hill, Jonathan D Geiger, Olimpia Meucci
The trafficking behavior of the lipid raft-dwelling US9 protein from Herpes Simplex Virus strikingly overlaps with that of the amyloid precursor protein (APP). Both US9 and APP processing machinery rely on their ability to shuttle between endosomes and plasma membranes, as well as on their lateral accumulation in lipid rafts. Therefore, repurposing US9 to track/modify these molecular events represents a valid approach to investigate pathological states including Alzheimer's disease and HIV-associated neurocognitive disorders where APP misprocessing to amyloid beta formation has been observed...
November 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29111698/assembly-of-lyotropic-liquid-crystals-with-solid-crystal-s-structural-order-translated-from-the-lipid-rafts-in-cell-membranes
#18
Yoon Seob Lee
Self-assembly offers a powerful way to control the complexity and hierarchy of nanoscale materials, and promises to create a diverse range of emergent properties. Successful syntheses that allow a delicate structural design of building units play an important role. However, as can be learned from many cellular processes and functions, co-self-assembly using logically chosen additives should be equally effective in designing self-assembly. Herein I show that, translated from the dynamic nanoscale assemblies in cell membranes known as lipid rafts, co-self-assembly of 1-decanol into cetyltrimethylammonium chloride micelles for the assembly of lyotropic liquid crystals generates new structural complexity and hierarchy, and a surprising property that is emerging from it...
November 7, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29108957/matrix-vesicles-from-chondrocytes-and-osteoblasts-their-biogenesis-properties-functions-and-biomimetic-models
#19
REVIEW
Massimo Bottini, Saida Mebarek, Karen L Anderson, Agnieszka Strzelecka-Kiliszek, Lukasz Bozycki, Ana Maria Sper Simão, Maytê Bolean, Pietro Ciancaglini, Joanna Bandorowicz Pikula, Slawomir Pikula, David Magne, Niels Volkmann, Dorit Hanein, José Luis Millán, Rene Buchet
BACKGROUND: Matrix vesicles (MVs) are released from hypertrophic chondrocytes and from mature osteoblasts, the cells responsible for endochondral and membranous ossification. Under pathological conditions, they can also be released from cells of non-skeletal tissues such as vascular smooth muscle cells. MVs are extracellular vesicles of approximately 100-300nm diameter harboring the biochemical machinery needed to induce mineralization. SCOPE OF THE REVIEW: The review comprehensively delineates our current knowledge of MV biology and highlights open questions aiming to stimulate further research...
November 3, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/29103614/membrane-microdomain-disassembly-inhibits-mrsa-antibiotic-resistance
#20
Esther García-Fernández, Gudrun Koch, Rabea M Wagner, Agnes Fekete, Stephanie T Stengel, Johannes Schneider, Benjamin Mielich-Süss, Sebastian Geibel, Sebastian M Markert, Christian Stigloher, Daniel Lopez
A number of bacterial cell processes are confined functional membrane microdomains (FMMs), structurally and functionally similar to lipid rafts of eukaryotic cells. How bacteria organize these intricate platforms and what their biological significance is remain important questions. Using the pathogen methicillin-resistant Staphylococcus aureus (MRSA), we show here that membrane-carotenoid interaction with the scaffold protein flotillin leads to FMM formation, which can be visualized using super-resolution array tomography...
October 26, 2017: Cell
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