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Macropinocytosis

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https://www.readbyqxmd.com/read/29329001/improved-antibacterial-activity-of-a-marine-peptide-n2-against-intracellular-salmonella-typhimurium-by-conjugating-with-cell-penetrating-peptides-blfcin6-tat11
#1
Zhanzhan Li, Xiao Wang, Da Teng, Ruoyu Mao, Ya Hao, Na Yang, Huixian Chen, Xiumin Wang, Jianhua Wang
Salmonellae, gram-negative bacteria, are facultative intracellular pathogens that cause a number of diseases in animals and humans. The poor penetration ability of antimicrobial agents limits their use in the treatment of intracellular bacterial infections. In this study, the cell-penetrating peptides (CPPs) bLFcin6 and Tat11 were separately conjugated to the antimicrobial peptide N2, and the antibacterial activity and pharmacodynamics of the CPPs-N2 conjugates were first evaluated against Salmonellae typhimurium in vitro and in macrophage cells...
December 29, 2017: European Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/29305166/internalization-of-large-particles-by-turbot-scophthalmus-maximus-igm-b-cells-mainly-depends-on-macropinocytosis
#2
Yi-Qun Li, Li Sun, Jun Li
Increasing evidence has demonstrated support for the endocytic capacities of teleost B cells. In the present study, the ability of turbot IgM+ B cells to ingest microspheres of different sizes and the corresponding internalization pathways were investigated. The results showed that IgM+ B cells exhibited relatively high endocytic capacities for 0.5 μm and 1 μm latex beads, and that different mechanisms were employed for IgM+ and IgM- cells to uptake 0.5 μm and 1 μm beads. For 0.5 μm beads, IgM+ B cells apparently employed macropinocytosis-dependent endocytic pathway, whereas IgM- cells utilized a different process involving both clathrin- and caveolae-mediated pathways...
January 2, 2018: Developmental and Comparative Immunology
https://www.readbyqxmd.com/read/29282279/renitence-vacuoles-facilitate-protection-against-phagolysosomal-damage-in-activated-macrophages
#3
Amanda O Wong, Matangi Marthi, Zachary I Mendel, Brian Gregorka, Michele S Swanson, Joel A Swanson
As professional phagocytes, macrophages are susceptible to endolysosomal membrane damage inflicted by the pathogens and noxious particles they ingest. Whether macrophages have mechanisms for limiting such damage is not well understood. Previously we reported a phenomenon, termed "inducible renitence," in which LPS activation of macrophages protected their endolysosomes against damage initiated by the phagocytosis of silica beads. To gain mechanistic insight into the process, we analyzed the kinetics of renitence and morphological features of LPS-activated versus resting macrophages following silica bead-mediated injury...
December 27, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/29277006/hiv-internalization-into-oral-and-genital-epithelial-cells-by-endocytosis-and-macropinocytosis-leads-to-viral-sequestration-in-the-vesicles
#4
Aizezi Yasen, Rossana Herrera, Kristina Rosbe, Kathy Lien, Sharof M Tugizov
Recently, we showed that HIV-1 is sequestered, i.e., trapped, in the intracellular vesicles of oral and genital epithelial cells. Here, we investigated the mechanisms of HIV-1 sequestration in vesicles of polarized tonsil, foreskin and cervical epithelial cells. HIV-1 internalization into epithelial cells is initiated by multiple entry pathways, including clathrin-, caveolin/lipid raft-associated endocytosis and macropinocytosis. Inhibition of HIV-1 attachment to galactosylceramide and heparan sulfate proteoglycans, and virus endocytosis and macropinocytosis reduced HIV-1 sequestration by 30-40%...
December 22, 2017: Virology
https://www.readbyqxmd.com/read/29273317/surface-coating-affects-uptake-of-silver-nanoparticles-in-neural-stem-cells
#5
Igor M Pongrac, Lada Brkić Ahmed, Hrvoje Mlinarić, Darija Domazet Jurašin, Ivan Pavičić, Ana Marija Marjanović Čermak, Mirta Milić, Srećko Gajović, Ivana Vinković Vrček
The rapid development and widespread applications of nanotechnology necessitates the design towards safe nanoparticles. Surface structure is among the most important physicochemical characteristics of metallic nanoparticles affecting their mode of action in certain biological or environmental compartments. This study aimed to investigate how different surface coatings affect the cytotoxicity and cellular uptake of silver nanoparticles (AgNPs) in murine neural stem cells (mNSCs). Different AgNPs were prepared by stabilisation with surface coatings encompassing sodium bis(2-ethylhexyl)-sulfosuccinate (AOT), cetyltrimethylammonium bromide (CTAB), poly(vinylpyrrolidone) (PVP), poly-l-lysine (PLL), and bovine serum albumin (BSA)...
December 16, 2017: Journal of Trace Elements in Medicine and Biology
https://www.readbyqxmd.com/read/29248729/a-novel-3d-heterotypic-spheroid-model-for-studying-extracellular-vesicle-mediated-tumour-and-immune-cell-communication
#6
Lilite Sadovska, Elīna Zandberga, Krizia Sagini, Kaspars Jēkabsons, Una Riekstiņa, Zane Kalniņa, Alicia Llorente, Aija Linē
Cancer-derived extracellular vesicles (EVs) have emerged as important mediators of tumour-host interactions, and they have been shown to exert various functional effects in immune cells. In most of the studies on human immune cells, EVs have been isolated from cancer cell culture medium or patients' body fluids and added to the immune cell cultures. In such a setting, the physiological relevance of the chosen EV concentration is unknown and the EV isolation method and the timing of EV administration may bias the results...
December 14, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/29247010/cell-penetrating-peptides-derived-from-clostridium-difficile-tcdb2-and-a-related-large-clostridial-toxin
#7
Jason L Larabee, Garrett D Hauck, Jimmy D Ballard
Clostridium difficile TcdB (2366 amino acid residues) is an intracellular bacterial toxin that binds to cells and enters the cytosol where it glucosylates small GTPases. In the current study, we examined a putative cell entry region of TcdB (amino acid residues 1753-1851) for short sequences that function as cell penetrating peptides (CPPs). To screen for TcdB-derived CPPs, a panel of synthetic peptides were tested for the ability to enhance transferrin (Tf) association with cells. Four candidate CPPs were discovered and further study on one peptide (PepB2) pinpointed an asparagine residue necessary for CPP activity...
December 15, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29241687/mechanisms-of-carrier-formation-during-clathrin-independent-endocytosis
#8
REVIEW
Antonio P A Ferreira, Emmanuel Boucrot
Clathrin-independent endocytosis (CIE) mediates the cellular uptake of many extracellular ligands, receptors, and pathogens, including several life-threatening bacterial toxins and viruses. So far, our understanding of CIE carrier formation has lagged behind that of clathrin-coated vesicles. Impediments have been the imprecise definition of some CIE pathways, the lack of specific cargoes being transported and of exclusive cytosolic markers and regulators. Notwithstanding these limitations, three distinct molecular mechanisms by which CIE carriers form can be defined...
December 11, 2017: Trends in Cell Biology
https://www.readbyqxmd.com/read/29237830/axl-can-serve-as-entry-factor-for-lassa-virus-depending-on-the-functional-glycosylation-of-dystroglycan
#9
Chiara Fedeli, Giulia Torriani, Clara Galan-Navarro, Marie-Laurence Moraz, Hector Moreno, Gisa Gerold, Stefan Kunz
Fatal infection with the highly pathogenic Lassa virus (LASV) is characterized by extensive viral dissemination, indicating broad tissue tropism. The major cellular receptor for LASV is the highly conserved extracellular matrix receptor dystroglycan (DG). Binding of LASV depends on DG's tissue-specific post-translational modification with the unusual O-linked polysaccharide matriglycan. Interestingly, functional glycosylation of DG does not always correlate with viral tropism observed in vivo The broadly expressed phosphatidylserine (PS) receptors Axl and Tyro3 were recently identified as alternative LASV receptor candidates...
December 13, 2017: Journal of Virology
https://www.readbyqxmd.com/read/29209647/targeting-ras-will-gpr31-deliver-us-a-new-path-forward
#10
Nicole Fehrenbacher, Mark R Philips
Effective anti-rat sarcoma viral oncogene (RAS) therapies have remained the holy grail of cancer treatment. Mutant Kirsten rat sarcoma viral oncogene homolog (KRAS) sustains tumorigenesis when linked to the plasma membrane (PM). The G protein-coupled receptor 31 (GPR31) is now identified to mediate KRAS membrane association and is crucial for proliferation, survival and macropinocytosis of KRAS-dependent cancer cells, suggesting that GPR31 is a druggable target for anti-RAS therapy.
2017: Molecular & Cellular Oncology
https://www.readbyqxmd.com/read/29173029/enzymatically-synthesized-megalo-type-isomaltosaccharides-enhance-the-barrier-function-of-the-tight-junction-in-the-intestinal-epithelium
#11
Hiroshi Hara, Shunsuke Kume, Takahisa Iizuka, Yoshinori Fujimoto, Atsuo Kimura
Megalo-type isomaltosaccharides are an enzymatically synthesized foodstuff produced by transglucosylation from maltodextrin, and they contain a mid-chain length polymer of D-glucose with α-1,6-glycoside linkages. The injection of a solution of megalo-type isomaltosaccharides (1-4%(w/v), average DP = 12.6), but not oligo-type isomaltosaccharides (average DP = 3.3), into the intestinal lumen dose-dependently reduced the transport rates of tight junction permeable markers in a ligated loop of the anesthetized rat jejunum...
November 27, 2017: Bioscience, Biotechnology, and Biochemistry
https://www.readbyqxmd.com/read/29167336/an-insight-into-the-role-of-e3-ubiquitin-ligase-c-cbl-escrt-machinery-and-host-cell-signaling-in-kaposi-s-sarcoma-associated-herpesvirus-kshv-entry-and-trafficking
#12
Binod Kumar, Arunava Roy, Mohanan Valiya Veettil, Bala Chandran
Kaposi's sarcoma-associated herpesvirus (KSHV) in vitro infection of dermal endothelial cell begins with its binding to host cell surface receptor molecules such as heparan sulfate (HS), integrins (α3β1, αVβ3 and αVβ5), xCT and EphA2 receptor tyrosine kinase (EphA2R). These initial events initiate dynamic host protein-protein interactions involving a multi-molecular complex of receptors, signal molecules (FAK, Src, PI3-K, RhoA-GTPase), adaptors (c-Cbl, CIB1, Crk, p130Cas and GEF-C3G), and actin/myosin II light chain that leads to virus entry via macropinocytosis...
November 22, 2017: Journal of Virology
https://www.readbyqxmd.com/read/29152126/extracellular-atp-as-an-energy-and-phosphorylating-molecule-induces-different-types-of-drug-resistances-in-cancer-cells-through-atp-internalization-and-intracellular-atp-level-increase
#13
Xuan Wang, Yunsheng Li, Yanrong Qian, Yanyang Cao, Pratik Shriwas, Haiyun Zhang, Xiaozhuo Chen
Cancer cells are able to uptake extracellular ATP (eATP) via macropinocytosis to elevate intracellular ATP (iATP) levels, enhancing their survival in drug treatment. However, the involved drug resistance mechanisms are unknown. Here we investigated the roles of eATP as either an energy or a phosphorylating molecule in general drug resistance mediated by ATP internalization and iATP elevation. We report that eATP increased iATP levels and promoted drug resistance to various tyrosine kinase inhibitors (TKIs) and chemo-drugs in human cancer cell lines of five cancer types...
October 20, 2017: Oncotarget
https://www.readbyqxmd.com/read/29150487/dynamin-inhibitors-block-mtorc1-activation-by-amino-acids-independently-of-dynamin
#14
Persaud Avinash, Cormerais Yann, Pouyssegur Jacques, Rotin Daniela
mTORC1 plays a critical role in protein synthesis and cell proliferation and growth. It is activated by growth factors and amino acids, including essential amino acid (EAA), such as Leu; Leu enters cells via the Leu transporter LAT1-4F2hc and potentially via endocytosis. Here we investigated the contribution of the different routes of Leu entry into cells to mTORC1 activation using pharmacological inhibitors and cells that lack LAT1 or dynamin1/2/3. Our results show that LAT1 is the major route of Leu entry into cells and mTORC1 activation (∼70%), while dynamin-dependent endocytosis and macropinocytosis contribute minimally to both (5-15%)...
November 17, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/29119997/dimeric-camptothecin-loaded-rgd-modified-targeted-cationic-polypeptide-based-micelles-with-high-drug-loading-capacity-and-redox-responsive-drug-release-capability
#15
Zhaopei Guo, Xingzhi Zhou, Mengze Xu, Huayu Tian, Xuesi Chen, Meiwan Chen
Camptothecin (CPT) is a broad spectrum anticancer drug, but its application is limited due to the poor water solubility, lactone ring instability, and low drug loading potential. In this study, biocompatible cationic polypeptide-based micelles were developed to deliver dimeric CPT (DCPT) with the aim of overcoming the above-mentioned obstacles and achieving favorable therapeutic effects. Cationic polypeptide poly-lysine-block-poly-leucine (PLys-b-PLeu) was fabricated via the ring-opening polymerization of N-ε-carbobenzoxy-l-lysine (ε-Lys(Z)) and l-leucine (Leu) and further grafted with polyethylene glycol (PEG) and an arginine-glycine-aspartic acid (RGD) peptide...
November 9, 2017: Biomaterials Science
https://www.readbyqxmd.com/read/29119228/macropinocytosis-mtorc1-and-cellular-growth-control
#16
REVIEW
Sei Yoshida, Regina Pacitto, Ken Inoki, Joel Swanson
The growth and proliferation of metazoan cells are driven by cellular nutrient status and by extracellular growth factors. Growth factor receptors on cell surfaces initiate biochemical signals that increase anabolic metabolism and macropinocytosis, an actin-dependent endocytic process in which relatively large volumes of extracellular solutes and nutrients are internalized and delivered efficiently into lysosomes. Macropinocytosis is prominent in many kinds of cancer cells, and supports the growth of cells transformed by oncogenic K-Ras...
November 8, 2017: Cellular and Molecular Life Sciences: CMLS
https://www.readbyqxmd.com/read/29117102/mechanisms-of-entry-and-endosomal-pathway-of-african-swine-fever-virus
#17
REVIEW
Elena G. Sánchez, Daniel Pérez-Núñez, Yolanda Revilla
African Swine Fever Virus (ASFV) causes a serious swine disease that is endemic in Africa and Sardinia and presently spreading in Russia and neighboring countries, including Poland and recently, the Czech Republic. This uncontrolled dissemination is a world-wide threat, as no specific protection or vaccine is available. ASFV is a very complex icosahedral, enveloped virus about 200 nm in diameter, which infects several members of pigs. The virus enters host cells by receptor-mediated endocytosis that depends on energy, vacuolar pH and temperature...
November 8, 2017: Vaccines
https://www.readbyqxmd.com/read/29115333/an-apolipoprotein-enriched-biomolecular-corona-switches-the-cellular-uptake-mechanism-and-trafficking-pathway-of-lipid-nanoparticles
#18
L Digiacomo, F Cardarelli, D Pozzi, S Palchetti, M A Digman, E Gratton, A L Capriotti, M Mahmoudi, G Caracciolo
Following exposure to biological milieus (e.g. after systemic administration), nanoparticles (NPs) get covered by an outer biomolecular corona (BC) that defines many of their biological outcomes, such as the elicited immune response, biodistribution, and targeting abilities. In spite of this, the role of BC in regulating the cellular uptake and the subcellular trafficking properties of NPs has remained elusive. Here, we tackle this issue by employing multicomponent (MC) lipid NPs, human plasma (HP) and HeLa cells as models for nanoformulations, biological fluids, and target cells, respectively...
November 16, 2017: Nanoscale
https://www.readbyqxmd.com/read/29113042/ph-responsive-micelle-based-cytoplasmic-delivery-system-for-induction-of-cellular-immunity
#19
Eiji Yuba, Naoki Sakaguchi, Yuhei Kanda, Maiko Miyazaki, Kazunori Koiwai
(1) Background: Cytoplasmic delivery of antigens is crucial for the induction of cellular immunity, which is an important immune response for the treatment of cancer and infectious diseases. To date, fusogenic protein-incorporated liposomes and pH-responsive polymer-modified liposomes have been used to achieve cytoplasmic delivery of antigen via membrane rupture or fusion with endosomes. However, a more versatile cytoplasmic delivery system is desired for practical use. For this study, we developed pH-responsive micelles composed of dilauroyl phosphatidylcholine (DLPC) and deoxycholic acid and investigated their cytoplasmic delivery performance and immunity-inducing capability...
November 4, 2017: Vaccines
https://www.readbyqxmd.com/read/29106503/induction-of-non-apoptotic-programmed-cell-death-by-oncogenic-ras-in-human-epithelial-cells-and-its-suppression-by-myc-overexpression
#20
Kasumi Dendo, Takashi Yugawa, Tomomi Nakahara, Shin-Ichi Ohno, Naoki Goshima, Hirofumi Arakawa, Tohru Kiyono
Oncogenic mutations of RAS genes, found in about 30% of human cancers, are considered to play important roles in cancer development. However, oncogenic RAS can also induce senescence in mouse and human normal fibroblasts. In some cell lines, oncogenic RAS has been reported to induce non-apoptotic programed cell death (PCD). Here, we investigated effects of oncogenic RAS expression in several types of normal human epithelial cells. Oncogenic RAS but not wild-type RAS stimulated macropinocytosis with accumulation of large phase-lucent vacuoles in the cytoplasm, subsequently leading to cell death which was indistinguishable from a recently proposed new type of PCD, methuosis...
November 2, 2017: Carcinogenesis
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