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Xiaofeng Liu, Mi Zhou, Yanling Yang, Jing Wu, Qisheng Peng
Brucella Cu-Zn superoxide dismutase (Cu-Zn SOD) is a periplasmic protein, and immunization of mice with recombinant Cu-Zn SOD protein confers protection against Brucella abortus infection. However, the role of Cu-Zn SOD during the process of Brucella infection remains unknown. Here, we report that Cu-Zn SOD is secreted into culture medium and is translocated into host cells independent of type IV secretion systems (T4SS). Furthermore, co-immunoprecipitation and immunofluorescence studies reveal that Brucella abortus Cu-Zn SOD interacts with the small GTPase Sar1...
February 9, 2018: Oncotarget
Kentaro Oh-Hashi, Ayano Soga, Yoshihisa Naruse, Kanto Takahashi, Kazutoshi Kiuchi, Yoko Hirata
CREB3 is an ER membrane-bound transcription factor; however, post-translational regulation of CREB3, including expression, processing, and activation, is not fully characterized. We therefore constructed several types of mouse CREB3 expression genes and elucidated their expression in Neuro2a cells by treatment with stimuli and co-transfection with genes associated with ER-Golgi homeostasis, such as mutant Sar1 [H79G], GRP78, and KDEL receptor 1 (KDELR1). Interestingly, treatment of Neuro2a cells expressing Flag-tagged full-length CREB3 with monensin and nigericin induced the expression of the approximately 50 kDa N-terminal fragment; however, its cleavage was not parallel to the levels of GADD153 and LC3-II...
February 17, 2018: Molecular and Cellular Biochemistry
Serdar Durdagi, Busecan Aksoydan, Ismail Erol, Isik Kantarcioglu, Yavuz Ergun, Gulay Bulut, Melih Acar, Timucin Avsar, George Liapakis, Vlasios Karageorgos, Ramin E Salmas, Barış Sergi, Sara Alkhatib, Gizem Turan, Berfu Nur Yigit, Kutay Cantasir, Bahar Kurt, Turker Kilic
AT1 antagonists is the most recent drug class of molecules against hypertension and they mediate their actions through blocking detrimental effects of angiotensin II (A-II) when acts on type I (AT1) A-II receptor. The effects of AT1 antagonists are not limited to cardiovascular diseases. AT1 receptor blockers may be used as potential anti-cancer agents - due to the inhibition of cell proliferation stimulated by A-II. Therefore, AT1 receptors and the A-II biosynthesis mechanisms are targets for the development of new synthetic drugs and therapeutic treatment of various cardiovascular and other diseases...
December 11, 2017: European Journal of Medicinal Chemistry
Mark Kwaaitaal, Mads Eggert Nielsen, Henrik Böhlenius, Hans Thordal-Christensen
Many filamentous plant pathogens place specialized feeding structures, called haustoria, inside living host cells. As haustoria grow, they are believed to manipulate plant cells to generate a specialized, still enigmatic extrahaustorial membrane (EHM) around them. Here, we focused on revealing properties of the EHM. With the help of membrane-specific dyes and transient expression of membrane-associated proteins fused to fluorescent tags, we studied the nature of the EHM generated by barley leaf epidermal cells around powdery mildew haustoria...
December 9, 2017: Journal of Experimental Botany
Arnaud T Djami-Tchatchou, Efficient N Ncube, Paul A Steenkamp, Ian A Dubery
BACKGROUND: Plants respond to various stress stimuli by activating an enhanced broad-spectrum defensive ability. The development of novel resistance inducers represents an attractive, alternative crop protection strategy. In this regard, hexanoic acid (Hxa, a chemical elicitor) and azelaic acid (Aza, a natural signaling compound) have been proposed as inducers of plant defense, by means of a priming mechanism. Here, we investigated both the mode of action and the complementarity of Aza and Hxa as priming agents in Nicotiana tabacum cells in support of enhanced defense...
November 29, 2017: BMC Plant Biology
Samra Joke Sanni, Christina Lyngsø, Steen Gammeltoft, Jakob Lerche Hansen
The angiotensin II type I receptor (AT1R) is involved in the regulation of cardiovascular function. Excessive activation of AT1R by angiotensin II (Ang II) leads to cardiovascular disease and may be involved in the development of insulin resistance and diabetes. Functionally selective Ang II analogues, such as the [Sar1, Ile4, Ile8]-angiotensin II (SII Ang II) analogue that only activates a subset of signalling networks have been demonstrated to have beneficial effects on cardiovascular function in certain settings, including lowering blood pressure and increasing cardiac performance...
November 14, 2017: Basic & Clinical Pharmacology & Toxicology
Manoj K Singh, Gerd Jürgens
Approximately one-third of all eukaryotic proteins are delivered to their destination by trafficking within the endomembrane system. Such cargo proteins are incorporated into forming membrane vesicles on donor compartments and delivered to acceptor compartments by vesicle fusion. How cargo proteins are sorted into forming vesicles is still largely unknown. Here we review the roles of small GTPases of the ARF/SAR1 family, their regulators designated ARF guanine-nucleotide exchange factors (ARF-GEFs) and ARF GTPase-activating proteins (ARF-GAPs) as well as coat protein complexes during membrane vesicle formation...
October 12, 2017: Seminars in Cell & Developmental Biology
Alain Théophile Sané, Ernest Seidman, Noel Peretti, Marie Laure Kleme, Edgard Delvin, Colette Deslandres, Carole Garofalo, Schohraya Spahis, Emile Levy
BACKGROUND: Understanding the specific mechanisms of rare autosomal disorders has greatly expanded insights into the complex processes regulating intestinal fat transport. Sar1B GTPase is one of the critical proteins governing chylomicron secretion by the small intestine, and its mutations lead to chylomicron retention disease, despite the presence of Sar1A paralog. OBJECTIVE: The central aim of this work is to examine the cause-effect relationship between Sar1B expression and chylomicron output and to determine whether Sar1B is obligatory for normal high-density lipoprotein biogenesis...
December 2017: Arteriosclerosis, Thrombosis, and Vascular Biology
Kota Saito, Miharu Maeda, Toshiaki Katada
Proteins synthesized within the endoplasmic reticulum (ER) are transported to the Golgi via coat protein complex II (COPII)-coated vesicles. The formation of COPII-coated vesicles is regulated by the GTPase cycle of Sar1. Activated Sar1 is recruited to ER membranes and forms a pre-budding complex with cargoes and the inner-coat complex. The outer-coat complex then stimulates Sar1 inactivation and completes vesicle formation. The mechanisms of forming transport carriers are well-conserved among species; however, in mammalian cells, several cargo molecules such as collagen, and chylomicrons are too large to be accommodated in conventional COPII-coated vesicles...
2017: Frontiers in Cell and Developmental Biology
Ekaterina A Lazareva, Alexander A Lezzhov, Sergey A Golyshev, Sergey Y Morozov, Manfred Heinlein, Andrey G Solovyev
The cell-to-cell transport of many plant viruses through plasmodesmata requires viral movement proteins (MPs) encoded by a 'triple gene block' (TGB) and termed TGB1, TGB2 and TGB3. TGB3 is a small integral membrane protein that contains subcellular targeting signals and directs both TGB2 and the helicase domain-containing TGB1 protein to plasmodesmata-associated structures. Recently, we described a 'binary movement block' (BMB) coding for two MPs, BMB1 and BMB2. The BMB2 protein associates with endoplasmic reticulum (ER) membranes, accumulates at plasmodesmata-associated membrane bodies and directs the BMB1 helicase to these structures...
September 2017: Journal of General Virology
Yoko Ito, Tomohiro Uemura, Akihiko Nakano
Many questions remain about how the stacked structure of the Golgi apparatus is formed and maintained. In our previous study, we challenged this question using tobacco BY-2 cells and revealed that, upon Brefeldin A (BFA) treatment, previously undescribed small punctate structures containing a particular subset of cis-Golgi proteins are formed adjacent to the ER exit sites and act as the scaffold of Golgi regeneration after BFA removal. In this study, we have analyzed these structures further. The proteins that localize to these punctate structures originate from the cis-most cisternae...
August 24, 2017: Journal of Cell Science
Ana C Alcalá, Raiza Hernández-Bravo, Fernando Medina, David S Coll, Jose L Zambrano, Rosa M Del Angel, Juan E Ludert
Dengue virus NS1 is a glycoprotein of 46-50 kDa that is conserved among flaviviruses, associates as a dimer to cell membranes and is secreted as a hexamer to the extracellular milieu. Recent evidence showed that NS1 is secreted efficiently from infected mosquito cells. To explore the secretory route of NS1 in mosquito cells, infected cells were treated with brefeldin A (BFA) and methyl-beta-cyclodextrin (MβCD). The results showed that MβCD, but not BFA, significantly reduced the release of NS1. Moreover, silencing the expression of caveolin-1 (CAV1; a key component of the caveolar system that transports cholesterol inside the cell), but not SAR1 (a GTPase that participates in the classical secretory pathway), also results in a significant reduction of the secretion of NS1...
August 2017: Journal of General Virology
Stephan Rips, Manuel Frank, Annegret Elting, Jan Niklas Offenborn, Antje von Schaewen
We analyzed plant-derived α1,4-fucosyltransferase (FucTc) homologs by reporter fusions and focused on representatives of the Brassicaceae and Solanaceae. Arabidopsis thaliana AtFucTc-green fluorescent protein (GFP) or tomato LeFucTc-GFP restored Lewis-a formation in a fuctc mutant, confirming functionality in the trans-Golgi. AtFucTc-GFP partly accumulated at the nuclear envelope (NE) not observed for other homologs or truncated AtFucTc lacking the N-terminus or catalytic domain. Analysis of At/LeFucTc-GFP swap constructs with exchanged cytosolic, transmembrane and stalk (CTS), or only the CT regions, revealed that sorting information resides in the membrane anchor...
July 28, 2017: Traffic
Hirohiko Iwasaki, Tomohiro Yorimitsu, Ken Sato
COPII coat and the small GTPase Sar1 mediate protein export from the endoplasmic reticulum (ER) via specialized domains known as the ER exit sites. The peripheral ER protein Sec16 has been proposed to organize ER exit sites. However, it remains unclear how these molecules drive COPII coat polymerization. Here, we characterized the spatiotemporal relationships between the COPII components during their polymerization using fluorescence microscopy combined with an artificial planar membrane. We demonstrated that Sar1 dissociates from the membrane shortly after the COPII coat recruitment, and Sar1 is then no longer required for the COPII coat to bind to the membrane...
July 26, 2017: Journal of Cell Science
Hiroshi Nakagawa, Kazuki Hazama, Katsumasa Ishida, Masayuki Komori, Kazuhiko Nishimura, Saburou Matsuo
Phospholipase D (PLD) plays a crucial role in the regulation of some cellular processes, including autophagy and apoptosis. Accumulation of protein in the endoplasmic reticulum (ER) lumen causes ER stress. Although ER stress is a principal cause of apoptosis and autophagy, the relationship between PLD activity and ER stress remains unclear. Protein transport from the ER to the Golgi apparatus is conducted by coat complex II (COPII) transport vesicles. Here, we demonstrated that inhibition of PLD1 activity or PLD1 knockdown suppressed COPII vesicle transport in normal rat kidney (NRK) cells...
August 26, 2017: Biochemical and Biophysical Research Communications
Fabrizio Barozzi, Gian-Pietro Di Sansebastiano, Erika Sabella, Alessio Aprile, Gabriella Piro, Luigi De Bellis, Eliana Nutricati
Triticum durum Glutathione S-transferase Z1 is specifically responsive to glyphosate. Its expression influences the receptor-mediated vacuolar sorting mechanisms involved in tolerance mechanisms. A zeta subfamily glutathione S-transferase gene from Triticum durum (cv Cappelli) (TdGSTZ1) was characterized as part of a complex detoxification mechanism. The effect of different abiotic stresses on TdGSTZ1 revealed that the gene is unexpectedly responsive to glyphosate (GLY) herbicide despite it should not be part of tolerance mechanisms...
September 2017: Plant Cell Reports
Smriti Parashar, Amitabha Mukhopadhyay
Metalloprotease gp63 (Leishmania donovani gp63 (Ldgp63)) is a critical virulence factor secreted by Leishmania However, how newly synthesized Ldgp63 exits the endoplasmic reticulum (ER) and is secreted by this parasite is unknown. Here, we cloned, expressed, and characterized the GTPase LdSar1 and other COPII components like LdSec23, LdSec24, LdSec13, and LdSec31 from Leishmania to understand their role in ER exit of Ldgp63. Using dominant-positive (LdSar1:H74L) and dominant-negative (LdSar1:T34N) mutants of LdSar1, we found that GTP-bound LdSar1 specifically binds to LdSec23, which binds, in turn, with LdSec24(1-702) to form a prebudding complex...
July 21, 2017: Journal of Biological Chemistry
Jiaxin Sun, Shiyan Yu, Xiao Zhang, Catherine Capac, Onyedikachi Aligbe, Timothy Daudelin, Edward M Bonder, Nan Gao
Wntless (Wls) transports Wnt molecules for secretion; however, the cellular mechanism underlying the initial assembly of Wnt secretory vesicles is still not fully defined. Here, we performed proteomic and mutagenic analyses of mammalian Wls, and report a mechanism for formation of early Wnt secretory vesicles on ER membrane. Wls forms a complex with SEC12 (also known as PREB), an ER membrane-localized guanine nucleotide-exchange factor (GEF) activator of the SAR1 (the SAR1A isoform) small GTPase. Compared to palmitoylation-deficient Wnt molecules, binding of mature Wnt to Wls increases Wls-SEC12 interaction and promotes association of Wls with SAR1, the key activator of the COPII machinery...
July 1, 2017: Journal of Cell Science
Matthew S Cook, Coralie Cazin, Marc Amoyel, Shinya Yamamoto, Erika Bach, Todd Nystul
The process of selecting for cellular fitness through competition plays a critical role in both development and disease. The germarium, a structure at the tip of the ovariole of a Drosophila ovary, contains two follicle stem cells (FSCs) that undergo neutral competition for the stem cell niche. Using the FSCs as a model, we performed a genetic screen through a collection of 126 mutants in essential genes on the X chromosome to identify candidates that increase or decrease competition for the FSC niche. We identified ∼55 and 6% of the mutations screened as putative FSC hypo- or hyper-competitors, respectively...
July 2017: Genetics
Sevil Yavuz, Graham Warren
A single Golgi stack is duplicated and partitioned into two daughter cells during the cell cycle of the protozoan parasite Trypanosoma brucei The source of components required to generate the new Golgi and the mechanism by which it forms are poorly understood. Using photoactivatable GFP, we show that the existing Golgi supplies components directly to the newly forming Golgi in both intact and semipermeabilized cells. The movement of a putative glycosyltransferase, GntB, requires the Sar1 and ARF1 GTPases in intact cells...
July 1, 2017: Molecular Biology of the Cell
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