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Cell trafficking

Helen L May-Simera, Jessica D Gumerson, Chun Gao, Maria Campos, Stephanie M Cologna, Tina Beyer, Karsten Boldt, Koray D Kaya, Nisha Patel, Friedrich Kretschmer, Matthew W Kelley, Ronald S Petralia, Megan G Davey, Tiansen Li
Microtubule actin crosslinking factor 1 (MACF1) plays a role in the coordination of microtubules and actin in multiple cellular processes. Here, we show that MACF1 is also critical for ciliogenesis in multiple cell types. Ablation of Macf1 in the developing retina abolishes ciliogenesis, and basal bodies fail to dock to ciliary vesicles or migrate apically. Photoreceptor polarity is randomized, while inner retinal cells laminate correctly, suggesting that photoreceptor maturation is guided by polarity cues provided by cilia...
October 25, 2016: Cell Reports
Ivan Kadurin, Laurent Ferron, Simon W Rothwell, James O Meyer, Leon R Douglas, Claudia S Bauer, Beatrice Lana, Wojciech Margas, Orpheas Alexopoulos, Manuela Nieto-Rostro, Wendy S Pratt, Annette C Dolphin
The auxiliary α2δ subunits of voltage-gated calcium channels are extracellular membrane-associated proteins, which are post-translationally cleaved into disulfide-linked polypeptides α2 and δ. We now show, using α2δ constructs containing artificial cleavage sites, that this processing is an essential step permitting voltage-dependent activation of plasma membrane N-type (CaV2.2) calcium channels. Indeed, uncleaved α2δ inhibits native calcium currents in mammalian neurons. By inducing acute cell-surface proteolytic cleavage of α2δ, voltage-dependent activation of channels is promoted, independent from the trafficking role of α2δ...
October 26, 2016: ELife
Frank Loganzo, Matthew Sung, Hans-Peter Gerber
Drug resistance limits the effectiveness of cancer therapies. Despite attempts to develop curative anticancer treatments, tumors evolve evasive mechanisms limiting durable responses. Hence, diverse therapies are used to attack cancer, including cytotoxic and targeted agents. Antibody-drug conjugates (ADC) are biotherapeutics designed to deliver potent cytotoxins to cancer cells via tumor-specific antigens. Little is known about the clinical manifestations of drug resistance to this class of therapy; however, recent preclinical studies reveal potential mechanisms of resistance...
October 25, 2016: Molecular Cancer Therapeutics
Meng Wang, Ying Li, Mingyi HuangFu, Yi Xiao, Tianyuan Zhang, Min Han, Donghang Xu, Fangyuan Li, Daishun Ling, Yi Jin, Jianqing Gao
AIM: To design pluronic F68 (PF68)-conjugated polyamidoamine (PAMAM) dendrimer conjugates for doxorubicin (DOX) delivery for overcoming multidrug resistance, and clarify the reversal mechanism. MATERIALS & METHODS: A series of PAMAM-PF68 conjugates were designed. The antitumor activity of the DOX-loaded conjugates was evaluated against MCF-7/ADR cells, tumor spheroids and tumors. Several bioinformatics were detected to characterize the reversal mechanism. RESULTS: Increased antitumor activity of the DOX-loaded conjugates was achieved in vitro and in vivo...
October 26, 2016: Nanomedicine
Chiara Tersigni, Fiorella Di Nicuolo, Giuseppe Maulucci, Alessandro Rolfo, Domenica Giuffrida, Manuela Veglia, Marco De Spirito, Giovanni Scambia, Tullia Todros, Nicoletta Di Simone
BACKGROUND: Pre-eclampsia (PE) is a major cause of maternal and perinatal morbidity and mortality worldwide. It is defined by new onset of hypertension and proteinuria after the 20th week of gestation and characterized by systemic exaggerated inflammatory response. D6 is a chemokines scavenger receptor that binds with high affinity CC chemokines, internalizes and targets the ligands for degradation. It is expressed in trophoblast-derived tissues and prevents excessive placenta leukocyte infiltration...
2016: PloS One
Cheng-Feng Chiang, Mike Flint, Jin-Mann S Lin, Christina F Spiropoulou
Andes virus (ANDV) is the major cause of hantavirus pulmonary syndrome (HPS) in South America. Despite a high fatality rate (up to 40%), no vaccines or antiviral therapies are approved to treat ANDV infection. To understand the role of endocytic pathways in ANDV infection, we used 3 complementary approaches to identify cellular factors required for ANDV entry into human lung microvascular endothelial cells. We screened an siRNA library targeting 140 genes involved in membrane trafficking, and identified 55 genes required for ANDV infection...
2016: PloS One
Catherine L Jackson, Laurence Walch, Jean-Marc Verbavatz
An evolutionarily conserved feature of cellular organelles is the distinct phospholipid composition of their bounding membranes, which is essential to their identity and function. Within eukaryotic cells, two major lipid territories can be discerned, one centered on the endoplasmic reticulum and characterized by membranes with lipid packing defects, the other comprising plasma-membrane-derived organelles and characterized by membrane charge. We discuss how this cellular lipid organization is maintained, how lipid flux is regulated, and how perturbations in cellular lipid homeostasis can lead to disease...
October 24, 2016: Developmental Cell
Jeffery S Babischkin, Graham W Aberdeen, Gerald J Pepe, Eugene D Albrecht
We have shown that fetal adrenal fetal zone (FZ) volume and serum dehydroepiandrosterone sulfate (DHAS) levels were increased, whereas definitive and transitional zone (DZ/TZ) volume was unaltered, in baboons in which estrogen levels were suppressed by administration of the aromatase inhibitor letrozole. The interaction of the melanocortin 2 receptor (MC2R) with its accessory protein (MRAP) is essential for trafficking MC2R to the adrenal cell surface for binding to ACTH. The present study determined whether the estrogen-dependent regulation of fetal adrenocortical development is mediated by ACTH and/or expression/interaction of MC2R and MRAP...
October 25, 2016: Endocrinology
Zheng Zhang, Hannah A Ledford, Seojin Park, Wenying Wang, Sassan Rafizadeh, Hyo Jeong Kim, Wilson Xu, Ling Lu, Victor C Lau, Anne A Knowlton, Xiao-Dong Zhang, Ebenezer N Yamoah, Nipavan Chiamvimonvat
The normal function of ion channels depends critically on the precise subcellular localization and the number of channel proteins on the cell surface membrane. Small-conductance, Ca(2+) -activated K(+) channels (SK, KCa 2) are expressed in human atrial myocytes and responsible for shaping atrial action potentials. Understanding the mechanisms of SK channel trafficking may provide new insights into the regulation controlling the repolarization of atrial myocytes. We have previously demonstrated that the C and N termini of SK2 channels interact with actin-binding proteins, α-actinin2 and filamin A, respectively...
October 25, 2016: Journal of Physiology
Katinka Karenberg, Hannes Hudalla, David Frommhold
Impaired cellular innate immune defense accounts for susceptibility to sepsis and its high morbidity and mortality in preterm infants. Leukocyte recruitment is an integral part of the cellular immune response and follows a well-defined cascade of events from rolling of leukocytes along the endothelium to firm adhesion and finally transmigration which is concerted by a variety of adhesion molecules. Recent analytical advances such as fetal intravital microscopy have granted new insights into ontogenetic regulation and maturation of fetal immune cell recruitment...
December 2016: Molecular and Cellular Pediatrics
Nasrin Dehghan-Nayeri, Mostafa Rezaei-Tavirani, Mir Davood Omrani, Ahmad Gharehbaghian, Kourosh Goudarzi Pour, Peyman Eshghi
Response to dexamethasone (DEXA), as a hallmark drug in the treatment of childhood acute lymphoblastic leukemia (ALL), is one of the pivotal prognostic factors in the prediction of outcome in ALL. Identification of predictive markers of chemoresistance is beneficial to selecting of the best therapeutic protocol with the lowest effect adverse. Hence, we aimed to find drug targets using the 2DE/MS proteomics study of a DEXA-resistant cell line (REH) as a model for poor DEXA responding patients before and after drug treatment...
October 24, 2016: Journal of Cell Communication and Signaling
Brie Sorrenson, Emmanuelle Cognard, Kathryn L Lee, Waruni C Dissanayake, Yanyun Fu, Weiping Han, William E Hughes, Peter R Shepherd
The processes regulating glucose-stimulated insulin secretion (GSIS) and its modulation by incretins in pancreatic β-cells are only partly understood. Here we investigate the involvement of β-catenin in these processes. Reducing β-catenin levels using siRNA knockdown attenuated GSIS in a range of β-cell models and blocked the ability of GLP-1 agonists and the depolarizing agent KCl to potentiate this. This could be mimicked in both β-cell models and isolated islets by short-term exposure to the β-catenin inhibitory drug pyrvinium...
October 24, 2016: Journal of Biological Chemistry
Joshua H K Tam, M Rebecca Cobb, Claudia Seah, Stephen H Pasternak
The amyloid hypothesis posits that the production of β-amyloid (Aβ) aggregates leads to neurodegeneration and cognitive decline associated with AD. Aβ is produced by sequential cleavage of the amyloid precursor protein (APP) by β- and γ-secretase. While nascent APP is well known to transit to the endosomal/ lysosomal system via the cell surface, we have recently shown that APP can also traffic to lysosomes intracellularly via its interaction with AP-3. Because AP-3 interacts with cargo protein via interaction with tyrosine motifs, we mutated the three tyrosines motif in the cytoplasmic tail of APP...
2016: PloS One
Daniel Vocelle, Olivia M Chesniak, Amanda P Malefyt, Georgina Comiskey, Kwasi Adu-Berchie, Milton R Smith, Christina Chan, S Patrick Walton
Understanding the endocytosis and intracellular trafficking of short interfering RNA (siRNA) delivery vehicle complexes remains a critical bottleneck in designing siRNA delivery vehicles for highly active RNA interference (RNAi)-based therapeutics. In this study, we show that dextran functionalization of silica nanoparticles enhanced uptake and intracellular delivery of siRNAs in cultured cells. Using pharmacological inhibitors for endocytotic pathways, we determined that our complexes are endocytosed via a previously unreported mechanism for siRNA delivery in which dextran initiates scavenger receptor-mediated endocytosis through a clathrin/caveolin-independent process...
March 2016: Technology
Hermann Koepsell
Orally applied SGLT2 (SLC5A2) inhibitors that enter the blood and decrease renal reabsorption of glucose have been approved as antidiabetic drugs. They decrease blood glucose levels, slightly reduce body weight and blood pressure, and decrease the risk for diabetic nephropathy. The SGLT2 inhibitor empagliflozin has been shown to reduce the risk of severe cardiac failure. This review summarizes knowledge about the functions of SGLT2 and the pathophysiology of type 2 diabetes (T2D) and diabetic follow-up diseases...
October 20, 2016: Pharmacology & Therapeutics
Christian Ostalecki, Sebastian Wittki, Jung-Hyun Lee, Miriam M Geist, Nadine Tibroni, Thomas Harrer, Gerold Schuler, Oliver T Fackler, Andreas S Baur
Tumor necrosis factor (TNF) is a key cytokine in HIV replication and pathogenesis. For reasons that are not entirely clear, the cytokine remains upregulated despite anti-retroviral therapy (ART). Here we demonstrate that HIV Nef induces an alternative TNF secretion mechanism that remains active in chronic infection. Ingestion of Nef-containing plasma extracellular vesicles (pEV) from ART patients by primary immune cells, but also Nef expression, induced intracellular proTNF cleavage and secretion of vesicular TNF endosomes...
October 19, 2016: EBioMedicine
Toni M Mueller, Stefani D Yates, Vahram Haroutunian, James H Meador-Woodruff
Glycosylation is a post-translational modification that is an essential element in cell signaling and neurodevelopmental pathway regulation. Glycan attachment can influence the tertiary structure and molecular interactions of glycosylated substrates, adding an additional layer of regulatory complexity to functional mechanisms underlying central cell biological processes. One type of enzyme-mediated glycan attachment, fucosylation, can mediate glycoprotein and glycolipid cell surface expression, trafficking, secretion, and quality control to modulate a variety of inter- and intracellular signaling cascades...
October 20, 2016: Schizophrenia Research
Dana Marcus, Michal Lichtenstein, Natali Cohen, Rita Hadad, Tal Erlich-Hadad, Hagar Greif, Haya Lorberboum-Galski
Mitochondrial Targeting Sequences (MTSs) are responsible for trafficking nuclear-encoded proteins into mitochondria. Once entering the mitochondria, the MTS is recognized and cleaved off. Some MTSs are long and undergo two-step processing, as in the case of the human frataxin (FXN) protein (80aa), implicated in Friedreich's ataxia (FA). Therefore, we chose the FXN protein to examine whether nuclear-encoded mitochondrial proteins can efficiently be targeted via a heterologous MTS (hMTS) and deliver a functional protein into mitochondria...
October 19, 2016: International Journal of Biochemistry & Cell Biology
Minyeop Nahm, Sunyoung Park, Jihye Lee, Seungbok Lee
Fasciclin II (FasII), the Drosophila ortholog of neural cell adhesion molecule (NCAM), plays a critical role in synaptic stabilization and plasticity. Although this molecule undergoes constitutive cycling at the synaptic membrane, how its membrane trafficking is regulated to ensure proper synaptic development remains poorly understood. In a genetic screen, we recovered a mutation in Drosophila mical-like that displays an increase in bouton numbers and a decrease in FasII levels at the neuromuscular junction (NMJ)...
October 21, 2016: Molecules and Cells
Henryka Długońska, Justyna Gatkowska
Extracellular vesicles – EV’s, including exosomes, are known to be essential tools of intercellular communication, enabling the exchange of information without direct contact between cells. Exosomes are secreted both in vitro and in vivo by single- and multi-cellular organisms, regardless of their type, and play an essential role in cell-to-cell communication. EV’s may carry various materials and ongoing studies have provided a new insight into their potential participation in various critical biological processes, including carcinogenesis, protein trafficking, immunostimulation and pathogenesis of infectious diseases...
October 1, 2016: Annals of Parasitology
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