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membrane proteins

Lingling Si, Xinyan Yan, Wenjin Hao, Xiaoyi Ma, Huanhuan Ren, Boxue Ren, Defang Li, Zhengping Dong, Qiusheng Zheng
The aim of the present study was to determine the effects of Licochalcone D (LD) on the apoptosis and migration and invasion in human melanoma A375 cells. Cell proliferation was determined by sulforhodamine B assay. Apoptosis was assessed by Hoechst 33258 and Annexin V‑FITC/PI staining and JC‑1 assay. Total intracellular reactive oxygen species (ROS) was examined by DCFH‑DA. Wound healing and Transwell assays were used to detect migration and invasion of the cells. The activities of matrix metalloproteinase (MMP‑2 and MMP‑9) were assessed via gelatin zymography...
May 2018: Oncology Reports
Jing Tao, Yu-Qin Zhao, Chang-Feng Chi, Bin Wang
In the experiment, crude proteins from spotless smoothhound ( Mustelus griseus ), cartilages were isolated by HCl-Guanidine buffer, and its hydrolysate was prepared using trypsin at pH 8.0, 40 °C with a total enzyme dose of 2.5%. Subsequently, three antioxidant peptides were purified from the hydrolysate using membrane ultrafiltration, anion-exchange chromatography, gel filtration chromatography, and reverse phase high-performance liquid chromatography. The amino acid sequences of isolated peptides were identified as Gly-Ala-Glu-Arg-Pro (MCPE-A); Gly-Glu-Arg-Glu-Ala-Asn-Val-Met (MCPE-B); and Ala-Glu-Val-Gly (MCPE-C) with molecular weights of 528...
March 22, 2018: Marine Drugs
Elena Khazina, Oliver Weichenrieder
LINE-1 (L1) is an autonomous retrotransposon, which acted throughout mammalian evolution and keeps contributing to human genotypic diversity, genetic disease and cancer. L1 encodes two essential proteins: L1ORF1p, a unique RNA-binding protein, and L1ORF2p, an endonuclease and reverse transcriptase. L1ORF1p contains an essential, but rapidly evolving N-terminal portion, homo-trimerizes via a coiled coil and packages L1RNA into large assemblies. Here, we determined crystal structures of the entire coiled coil domain of human L1ORF1p...
March 22, 2018: ELife
Ravit Malishev, Razan Abbasi, Raz Jelinek, Liraz Chai
Biofilms are aggregates of cells that form surface-associated communities. The cells in a biofilm are interconnected with an extracellular matrix, a network that is made mostly of polysaccharides, proteins and sometimes nucleic acids. Some extracellular matrix proteins form fibers, often termed functional amyloids or amyloid-like fibrils, to differentiate their constructive function from disease-related amyloid fibers. Recent studies of functional amyloid assembly have neglected their interaction with membranes, despite their native assembly in a cellular environment...
March 22, 2018: Biochemistry
Qingfen Yu, Sameh Othman, Sabyasachi Dasgupta, Thorsten Auth, Gerhard Gompper
Nanoparticles in biological systems encounter lipid-bilayer membranes as barriers. They interact with plasma membranes, membranous organelles, such as the endoplasmic reticulum and the Golgi apparatus, the nucleus, and intracellular and extracellular vesicles, such as autophagosomes, lysosomes, and exosomes. Extracellular vesicles have recently attracted particular attention, as they are involved in the transmission of biological signals and as regulators for biological processes. For example, exosomes, small vesicles containing proteins, mRNA, and miRNA, that are released by cells into the extracellular environment, have been suggested to participate in tumor metastasis...
March 22, 2018: Nanoscale
Marina A Gwairgi, Reena Ghildyal
Entamoeba histolytica is the protozoan parasite that causes human amoebiasis. It is one of the leading parasitic disease burdens in tropical regions and developing countries, with spread to developed countries through migrants from and travellers to endemic regions. Understanding E. histolytica's invasion mechanisms requires an understanding of how it interacts with external cell components and how it engulfs and kills cells (phagocytosis). Recent research suggests that optimal phagocytosis requires signalling events from the cell surface to the nucleus via the cytoplasm, and the induction of several factors that are transported to the plasma membrane...
March 22, 2018: Parasitology
Fernanda Silva Ferreira, Helena Biasibetti-Brendler, Paula Pierozan, Felipe Schmitz, Carolina Gessinger Bertó, Caroline Acauan Prezzi, Vanusa Manfredini, Angela T S Wyse
Kynurenic acid (KYNA) and quinolinic acid (QUIN) are metabolites produced in the degradation of tryptophan and have important neurological activities. KYNA/QUIN ratio changes are known to be associated with central nervous system disorders, such Alzheimer, Parkinson, and Huntington diseases. In the present study, we investigate the ability of KYNA in prevent the first events preceding QUIN-induced neurodegeneration in striatal slices of rat. We evaluated the protective effect of KYNA on oxidative status (reactive oxygen species production, antioxidant enzymes activities, lipid peroxidation, nitrite levels, protein and DNA damage, and iNOS immunocontent), mitochondrial function (mitochondrial mass, membrane potential, and respiratory chain enzymes), and Na+ ,K+ -ATPase in striatal slices of rats treated with QUIN...
March 21, 2018: Molecular Neurobiology
Clint L Makino, Teresa Duda, Alexandre Pertzev, Rameshwar K Sharma
Our ability to see is based on the activity of retinal rod and cone photoreceptors. Rods function when there is very little light, while cones operate at higher light levels. Photon absorption by rhodopsin activates a biochemical cascade that converts photic energy into a change in the membrane potential of the cell by decreasing the levels of a second messenger, cGMP, that control the gating of cation channels. But just as important as the activation of the cascade are the shut-off and recovery processes. The timing of shutoff and recovery ultimately affects sensitivity, temporal resolution and even the capacity for counting single photons...
2018: Methods in Molecular Biology
Yu-Ling Zou, Wen-Bin Luo, Lin Xie, Xin-Bang Mao, Chao Wu, Zhi-Peng You
PURPOSE: Diabetic retinopathy (DR) is a major vision threatening disease mainly induced by high glucose. Despite great efforts were made to explore the etiology of DR, the exact mechanism responsible for its pathogenesis remains elusive. METHODS: In our study, we constructed diabetic rats via Streptozotocin (STZ) injection. TUNEL assay was employed to examine retinal cell apoptosis. The levels of mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were analyzed via flow cytometry...
March 21, 2018: Endocrine
Muhammad Ehsan, Yang Du, Iago Molist, Alpay B Seven, Parameswaran Hariharan, Jonas S Mortensen, Lubna Ghani, Claus J Loland, Georgios Skiniotis, Lan Guan, Bernadette Byrne, Brian K Kobilka, Pil Seok Chae
Membrane proteins play critical roles in a variety of cellular processes. For a detailed molecular level understanding of their biological functions and roles in disease, it is necessary to extract them from the native membranes. While the amphipathic nature of these bio-macromolecules presents technical challenges, amphiphilic assistants such as detergents serve as useful tools for membrane protein structural and functional studies. Conventional detergents are limited in their ability to maintain the structural integrity of membrane proteins and thus it is essential to develop novel agents with enhanced properties...
March 22, 2018: Organic & Biomolecular Chemistry
Sean F Gilmore, Timothy S Carpenter, Helgi I Ingólfsson, Sandra K G Peters, Paul T Henderson, Craig D Blanchette, Nicholas O Fischer
Nanolipoprotein particles (NLPs) are reconstituted high-density lipoproteins, consisting of a phospholipid bilayer stabilized by an apolipoprotein scaffold protein. This class of nanoparticle has been a vital tool in the study of membrane proteins, and in recent years has been increasingly used for in vivo applications. Previous work demonstrated that the composition of the lipid bilayer component affects the stability of these particles in serum solutions. In the current study, NLPs assembled with phosphatidylcholine lipids featuring different acyl chain structures were systematically tested to understand the effect that lipid composition has on NLP stability in both neat serum and cell culture media supplemented with 10% serum by volume...
March 22, 2018: Nanoscale
Javier Cervera, José A Manzanares, Salvador Mafe
Genetic networks operate in the presence of local heterogeneities in single-cell transcription and translation rates. Bioelectrical networks and spatio-temporal maps of cell electric potentials can influence multicellular ensembles. Could cell-cell bioelectrical interactions mediated by intercellular gap junctions contribute to the stabilization of multicellular states against local genetic heterogeneities? We theoretically analyze this question on the basis of two well-established experimental facts: (i) the membrane potential is a reliable read-out of the single-cell electrical state and (ii) when the cells are coupled together, their individual cell potentials can be influenced by ensemble-averaged electrical potentials...
March 22, 2018: Physical Chemistry Chemical Physics: PCCP
Adrian J Giovannone, Elena Reales, Pallavi Bhattaram, Alberto Fraile-Ramos, Thomas Weimbs
The uptake and trafficking of cell surface receptors can be monitored by a technique called 'antibody-feeding' which uses an externally applied antibody to label the receptor on the surface of cultured, live cells. Here, we adapt the traditional antibody-feeding experiment to polarized epithelial cells (Madin-Darby Canine Kidney) grown on permeable Transwell supports. By adding two tandem extracellular Myc epitope tags to the C-terminus of the SNARE protein syntaxin 3 (Stx3), we provided a site where an antibody could bind, allowing us to perform antibody-feeding experiments on cells with distinct apical and basolateral membranes...
February 5, 2018: Bio-protocol
Kristina Shilnikova, Mei Jing Piao, Kyoung Ah Kang, Yea Seong Ryu, Jeong Eon Park, Yu Jae Hyun, Ao Xuan Zhen, Yong Joo Jeong, Uhee Jung, In Gyu Kim, Jin Won Hyun
Cisplatin-based chemotherapy often results in the development of chemoresistance when used to treat ovarian cancer, which is difficult to overcome. The present study investigated the cytotoxic and anti-migratory effects of shikonin, a naphthoquinone compound, on cisplatin-resistant human ovarian cancer A2780 cells (A2780-CR). Shikonin had a potent dose-dependent cytotoxic effect on A2780-CR cells, with 9 µM shikonin treatment reducing A2780-CR cell viability by 50%, validate using an MTT assay. Shikonin induced apoptosis, as evidenced by the increased number of apoptotic bodies, following staining with Hoechst 33342, and terminal deoxynucleotidyl cell transferase dUTP nick end labeling-positive cells following treatment...
April 2018: Oncology Letters
Guang-Dao Chen, Jun-Liang Zhang, Yi-Ting Chen, Ju-Xing Zhang, Tao Wang, Qi-Yi Zeng
The aim of the present study was to explore the effects and mechanisms of insulin on mitochondrial oxidative stress in septic acute kidney injury (AKI). Male Sprague Dawley rats were divided randomly into four groups: Control group, sham surgery group, cecal ligation and puncture (CLP) group, and CLP plus insulin group. Blood specimens and kidney tissues were obtained at 12 and 24 h after surgery as separate experiments. Analyses of histology and indicators of renal injury [blood urea nitrogen (BUN) and serum creatinine (CRE) and neutrophil gelatinase-associated lipocalin (NGAL)], mitochondrial function [adenosine triphosphate (ATP) and mitochondrial membrane potential (MMP)], oxidative stress [inducible nitric oxide synthase (iNOS), reactive oxygen species (ROS) and nitric oxide (NO)], endogenous antioxidant systems [superoxide dismutase (SOD) and glutathione (GSH)] as well as the expression of uncoupling protein (UCP), PINK1 protein (a major mediator of mitophagy), PGC1α protein (a major regulator of mitochondrial biogenesis) were performed...
April 2018: Experimental and Therapeutic Medicine
Mickaël Jacquet, Gianluca Cioci, Guillaume Fouet, Isabelle Bally, Nicole M Thielens, Christine Gaboriaud, Véronique Rossi
Complement receptor type 1 (CR1) is a multi modular membrane receptor composed of 30 homologous complement control protein modules (CCP) organized in four different functional regions called long homologous repeats (LHR A, B, C, and D). CR1 is a receptor for complement-opsonins C3b and C4b and specifically interacts through pairs of CCP modules located in LHR A, B, and C. Defense collagens such as mannose-binding lectin (MBL), ficolin-2, and C1q also act as opsonins and are involved in immune clearance through binding to the LHR-D region of CR1...
2018: Frontiers in Immunology
Kornelius Zeth, Ulrich Zachariae
Mitochondria are evolutionarily related to Gram-negative bacteria and both comprise two membrane systems with strongly differing protein composition. The major protein in the outer membrane of mitochondria is the voltage-dependent anion channel (VDAC), which mediates signal transmission across the outer membrane but also the exchange of metabolites, most importantly ADP and ATP. More than 30 years after its discovery three identical high-resolution structures were determined in 2008. These structures show a 19-stranded anti-parallel beta-barrel with an N-terminal helix located inside...
2018: Frontiers in Physiology
Lissette C Sánchez-Aranguren, Cindy T Espinosa-González, Laura M González-Ortiz, Sandra M Sanabria-Barrera, Carlos E Riaño-Medina, Andrés F Nuñez, Asif Ahmed, Jeannette Vasquez-Vivar, Marcos López
Preeclampsia is a maternal hypertensive disorder that affects up to 1 out of 12 pregnancies worldwide. It is characterized by proteinuria, endothelial dysfunction, and elevated levels of the soluble form of the vascular endothelial growth factor receptor-1 (VEGFR-1, known as sFlt-1). sFlt-1 effects are mediated in part by decreasing VEGF signaling. The direct effects of sFlt-1 on cellular metabolism and bioenergetics in preeclampsia, have not been established. The goal of this study was to evaluate whether sFlt-1 causes mitochondrial dysfunction leading to disruption of normal functioning in endothelial and placental cells in preeclampsia...
2018: Frontiers in Physiology
Johan Tolö, Grit Taschenberger, Kristian Leite, Markus A Stahlberg, Gesche Spehlbrink, Janina Kues, Francesca Munari, Stefano Capaldi, Stefan Becker, Markus Zweckstetter, Camin Dean, Mathias Bähr, Sebastian Kügler
α-Synuclein (α-Syn) is intimately linked to the etiology of Parkinson's Disease, as mutations and even subtle increases in gene dosage result in early onset of the disease. However, how this protein causes neuronal dysfunction and neurodegeneration is incompletely understood. We thus examined a comprehensive range of physiological parameters in cultured rat primary neurons overexpressing α-Syn at levels causing a slowly progressive neurodegeneration. In contradiction to earlier reports from non-neuronal assay systems we demonstrate that α-Syn does not interfere with essential ion handling capacities, mitochondrial capability of ATP production or basic electro-physiological properties like resting membrane potential or the general ability to generate action potentials...
2018: Frontiers in Molecular Neuroscience
Ryan A Kelley, Shannon M Conley, Rasha Makkia, Jamie N Watson, Zongchao Han, Mark J Cooper, Muna I Naash
Introduction: DNA nanoparticles (NPs) comprising polylysine conjugated to polyethylene glycol efficiently target murine photoreceptors and the retinal pigment epithelium (RPE) and lead to long-term phenotypic improvement in models of retinal degeneration. Advancing this technology requires testing in a large animal model, particularly with regard to safety. So, herein we evaluate NPs in non-human primates (baboon). Methods and results: NPs with plasmids carrying GFP and a ubiquitous, RPE-specific, or photoreceptor-specific promoter were delivered by either subretinal or intravitreal injection...
2018: International Journal of Nanomedicine
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