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https://www.readbyqxmd.com/read/28626835/disrupted-er-to-golgi-trafficking-underlies-anti-hiv-drugs-and-alcohol-induced-cellular-stress-and-hepatic-injury
#1
Hui Han, Yuxin He, Jay Hu, Rhema Lau, Harrison Lee, Cheng Ji
Endoplasmic reticulum (ER) stress and unfolded protein response (UPR) are involved in anti-human immunodeficiency virus (HIV) drugs and alcohol-induced liver disease in a significant number of patients infected with HIV. However, the precise mechanism by which the drugs and alcohol cause ER stress remains elusive. We found that ritonavir-boosted lopinavir (RL) activated two canonical UPR branches without activation of the third canonical activating transcription factor 6 (ATF6) branch in either HepG2 cells or primary mouse hepatocytes...
April 2017: Hepatol Commun
https://www.readbyqxmd.com/read/28594326/er-retention-is-imposed-by-copii-protein-sorting-and-attenuated-by-4-phenylbutyrate
#2
Wenfu Ma, Elena Goldberg, Jonathan Goldberg
Native cargo proteins exit the endoplasmic reticulum (ER) in COPII-coated vesicles, whereas resident and misfolded proteins are substantially excluded from vesicles by a retention mechanism that remains unresolved. We probed the ER retention process using the proteostasis regulator 4-phenylbutyrate (4-PBA), which we show targets COPII protein to reduce the stringency of retention. 4-PBA competes with p24 proteins to bind COPII. When p24 protein uptake is blocked, COPII vesicles package resident proteins and an ER-trapped mutant LDL receptor...
June 8, 2017: ELife
https://www.readbyqxmd.com/read/28576830/gtpase-sar1-regulates-the-trafficking-and-secretion-of-the-virulence-factor-gp63-in-leishmania
#3
Smriti Parashar, Amitabha Mukhopadhyay
Metalloprotease 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 LdSec241-702 to form a prebudding complex...
June 2, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28559361/ap3-adaptor-protein-dependent-vacuolar-trafficking-involves-a-subpopulation-of-copii-and-hops-tethering-proteins
#4
Qiang-Nan Feng, Shi-Jian Song, Shi-Xia Yu, Jia-Gang Wang, Sha Li, Yan Zhang
Plant vacuoles are versatile organelles critical for plant growth and responses to environment. Vacuolar proteins are transported from the endoplasmic reticulum (ER) via multiple routes in plants. Two classic routes bear great similarity to other phyla with major regulators known, such as COPII and Rab5 GTPases. By contrast, vacuolar trafficking mediated by adaptor protein-3 (AP-3) or that independent of Golgi has few recognized cargos and none of the regulators. In search of novel regulators for vacuolar trafficking routes and by using a fluorescence-based forward genetic screen, we demonstrated that the multi-span transmembrane protein, Arabidopsis PROTEIN S-ACYL TRANSFERASE 10 (PAT10), is an AP-3-mediated vacuolar cargo...
May 30, 2017: Plant Physiology
https://www.readbyqxmd.com/read/28553408/identification-of-cysteine-ubiquitylation-sites-on-the-sec23a-protein-of-the-copii-complex-required-for-vesicle-formation-from-the-er
#5
Giuseppina Amodio, Luigi Margarucci, Ornella Moltedo, Agostino Casapullo, Paolo Remondelli
BACKGROUND: COPII is a multiprotein complex that surrounds carrier vesicles budding from the Endoplasmic Reticulum and allows the recruitment of secretory proteins. The Sec23a protein plays a crucial role in the regulation of the dynamics of COPII formation ensuring the proper function of the secretory pathway. OBJECTIVE: Since few evidences suggest that ubiquitylation could have a role in the COPII regulation, the present study was aimed to establish whether the Sec23a component of the vesicular envelope COPII could be ubiquitylated...
2017: Open Biochemistry Journal
https://www.readbyqxmd.com/read/28553287/hypoxia-modulates-the-response-of-mast-cells-to-staphylococcus-aureus-infection
#6
Helene Möllerherm, Katja Branitzki-Heinemann, Graham Brogden, Ayssar A Elamin, Wulf Oehlmann, Herbert Fuhrmann, Mahavir Singh, Hassan Y Naim, Maren von Köckritz-Blickwede
To study the antimicrobial function of immune cells ex vivo, cells are commonly cultivated under atmospheric oxygen concentrations (20-21%; normoxia), although the physiological oxygen conditions in vivo are significantly lower in most tissues. Especially during an acute infection, oxygen concentration locally decreases to hypoxic levels around or below 1%. The goal of this study was to investigate the effect of hypoxia on the activity of mast cells (MCs). MCs were cultivated for 3 or 24 h at 1% O2 in a hypoxia glove box and co-incubated with heat-inactivated Staphylococcus aureus...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/28546447/signal-motifs-dependent-er-export-of-qc-snare-bet12-interacts-with-memb12-and-affects-pr1-trafficking-in-arabidopsis
#7
Kin Pan Chung, Yonglun Zeng, Yimin Li, Changyang Ji, Yiji Xia, Liwen Jiang
SNAREs are well-known for their role in controlling membrane fusion, the final but crucial step for vesicular transport in eukaryotes. SNARE proteins contribute to various biological processes including pathogen defense, channel activity regulation as well as plant growth and development. Precise targeting of SNARE proteins to destined compartments is a prerequisite for their proper functioning. However, the underlying mechanism(s) for SNAREs targeting in plants remains obscure. Here we investigate the targeting mechanism of the Qc-SNARE BET12, which is involved in protein trafficking in the early secretory pathway...
May 25, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28515296/hepatitis-c-virus-lipoviroparticles-hcv-lvp-assemble-in-the-endoplasmic-reticulum-er-and-bud-off-from-the-er-to-golgi-in-copii-vesicles
#8
Gulam H Syed, Mohsin Khan, Song Yang, Aleem Siddiqui
Hepatitis C virus (HCV) exists as a lipoprotein-virus hybrid lipoviroparticle (LVP). In vitro studies have demonstrated the importance of apolipoproteins in HCV secretion and infectivity leading to the notion that HCV co-opts the secretion of very-low density lipoprotein (VLDL) for its egress. However, our understanding of the mechanisms involved in virus particle assembly and egress, are still elusive. Biogenesis of VLDL particle occurs in the ER followed by subsequent lipidation in the ER and Golgi. Secretion of mature VLDL particles occurs through the Golgi secretory pathway...
May 17, 2017: Journal of Virology
https://www.readbyqxmd.com/read/28515233/wntless-sec12-complex-on-er-membrane-regulates-early-wnt-secretory-vesicle-assembly-and-mature-ligand-export
#9
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. Using proteomic and mutagenic analyses of the mammalian Wls, we report a mechanism for formation of early Wnt secretory vesicle on ER membrane. Wls forms a complex with SEC12, an ER membrane-localized GEF activator of SAR1 small GTPase. Compared to palmitoylation-deficient Wnt molecules, binding of mature Wnt to Wls increases Wls-SEC12 interaction and promotes Wls association with SAR1, the key activator of the COPII machinery...
May 17, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28500182/upr-transducer-bbf2h7-allows-export-of-type-ii-collagen-in-a-cargo-and-developmental-stage-specific-manner
#10
Tokiro Ishikawa, Takuya Toyama, Yuki Nakamura, Kentaro Tamada, Hitomi Shimizu, Satoshi Ninagawa, Tetsuya Okada, Yasuhiro Kamei, Tomoko Ishikawa-Fujiwara, Takeshi Todo, Eriko Aoyama, Masaharu Takigawa, Akihiro Harada, Kazutoshi Mori
The unfolded protein response (UPR) handles unfolded/misfolded proteins accumulated in the endoplasmic reticulum (ER). However, it is unclear how vertebrates correctly use the total of ten UPR transducers. We have found that ER stress occurs physiologically during early embryonic development in medaka fish and that the smooth alignment of notochord cells requires ATF6 as a UPR transducer, which induces ER chaperones for folding of type VIII (short-chain) collagen. After secretion of hedgehog for tissue patterning, notochord cells differentiate into sheath cells, which synthesize type II collagen...
June 5, 2017: Journal of Cell Biology
https://www.readbyqxmd.com/read/28499723/a-dual-site-gateway-cloning-system-for-simultaneous-cloning-of-two-genes-for-plant-transformation
#11
Mostafa Aboulela, Yuji Tanaka, Kohji Nishimura, Shoji Mano, Tetsuya Kimura, Tsuyoshi Nakagawa
Analyses of the subcellular localization of proteins and protein-protein interaction networks are essential to uncover the molecular basis of diverse biological processes in plants. To this end, we have created a Gateway cloning-compatible vector system, named dual-site (DS) Gateway cloning system to allow simple cloning of two expression cassettes in a binary vector and to express them simultaneously in plant cells. In the DS Gateway cloning system, (i) a moderate constitutive nopaline synthase promoter (Pnos), which is much suitable for localization analysis, is used to guide each expression cassette, (ii) four series of vectors with different plant resistance markers are established, (iii) N-terminal fusion with 6 fluorescent proteins and 7 epitope tags is available, (iv) both N- and C-terminal fusions with split enhanced yellow fluorescent protein (EYFP) are possible for efficient detection of protein-protein interactions using a bimolecular fluorescence complementation (BiFC) assay...
May 9, 2017: Plasmid
https://www.readbyqxmd.com/read/28486929/ulk1-phosphorylates-sec23a-and-mediates-autophagy-induced-inhibition-of-er-to-golgi-traffic
#12
Wenjia Gan, Caiyun Zhang, Ka Yu Siu, Ayano Satoh, Julian A Tanner, Sidney Yu
BACKGROUND: Autophagy is an inducible autodigestive process that allows cells to recycle proteins and other materials for survival during stress and nutrient deprived conditions. The kinase ULK1 is required to activate this process. ULK1 phosphorylates a number of target proteins and regulates many cellular processes including the early secretory pathway. Recently, ULK1 has been demonstrated to phosphorylate Sec16 and affects the transport of serotonin transporter at the ER exit sites (ERES), but whether ULK1 may affect the transport of other cargo proteins and general secretion has not been fully addressed...
May 10, 2017: BMC Cell Biology
https://www.readbyqxmd.com/read/28442536/tango1-recruits-sec16-to-coordinately-organize-er-exit-sites-for-efficient-secretion
#13
Miharu Maeda, Toshiaki Katada, Kota Saito
Mammalian endoplasmic reticulum (ER) exit sites export a variety of cargo molecules including oversized cargoes such as collagens. However, the mechanisms of their assembly and organization are not fully understood. TANGO1L is characterized as a collagen receptor, but the function of TANGO1S remains to be investigated. Here, we show that direct interaction between both isoforms of TANGO1 and Sec16 is not only important for their correct localization but also critical for the organization of ER exit sites. The depletion of TANGO1 disassembles COPII components as well as membrane-bound ER-resident complexes, resulting in fewer functional ER exit sites and delayed secretion...
June 5, 2017: Journal of Cell Biology
https://www.readbyqxmd.com/read/28428367/copii-coated-membranes-function-as-transport-carriers-of-intracellular-procollagen-i
#14
Amita Gorur, Lin Yuan, Samuel J Kenny, Satoshi Baba, Ke Xu, Randy Schekman
The coat protein complex II (COPII) is essential for the transport of large cargo, such as 300-nm procollagen I (PC1) molecules, from the endoplasmic reticulum (ER) to the Golgi. Previous work has shown that the CUL3-KLHL12 complex increases the size of COPII vesicles at ER exit sites to more than 300 nm in diameter and accelerates the secretion of PC1. However, the role of large COPII vesicles as PC1 transport carriers was not unambiguously demonstrated. In this study, using stochastic optical reconstruction microscopy, correlated light electron microscopy, and live-cell imaging, we demonstrate the existence of mobile COPII-coated vesicles that completely encapsulate the cargo PC1 and are physically separated from ER...
June 5, 2017: Journal of Cell Biology
https://www.readbyqxmd.com/read/28410007/key-roles-of-arf-small-g-proteins-and-biosynthetic-trafficking-for-animal-development
#15
Francisco F Rodrigues, Tony J C Harris
Although biosynthetic trafficking can function constitutively, it also functions specifically for certain developmental processes. These processes require either a large increase to biosynthesis or the biosynthesis and targeted trafficking of specific players. We review the conserved molecular mechanisms that direct biosynthetic trafficking, and discuss how their genetic disruption affects animal development. Specifically, we consider Arf small G proteins, such as Arf1 and Sar1, and their coat effectors, COPI and COPII, and how these proteins promote biosynthetic trafficking for cleavage of the Drosophila embryo, the growth of neuronal dendrites and synapses, extracellular matrix secretion for bone development, lumen development in epithelial tubes, notochord and neural tube development, and ciliogenesis...
April 14, 2017: Small GTPases
https://www.readbyqxmd.com/read/28301741/mechanisms-of-autophagy-initiation
#16
James H Hurley, Lindsey N Young
Autophagy is the process of cellular self-eating by a double-membrane organelle, the autophagosome. A range of signaling processes converge on two protein complexes to initiate autophagy: the ULK1 (unc51-like autophagy activating kinase 1) protein kinase complex and the PI3KC3- C1 (class III phosphatidylinositol 3-kinase complex I) lipid kinase complex. Some 90% of the mass of these large protein complexes consists of noncatalytic domains and subunits, and the ULK1 complex has essential noncatalytic activities...
March 15, 2017: Annual Review of Biochemistry
https://www.readbyqxmd.com/read/28292851/new-insights-into-protein-secretion-tango1-runs-rings-around-the-copii-coat
#17
Benjamin S Glick
In this issue, Liu et al. (2017. J. Cell Biol. https://doi.org/10.1083/jcb.201611088) and Raote et al. (2017. J. Cell Biol. https://doi.org/10.1083/jcb.201608080) use super-resolution microscopy to visualize large COPII-coated endoplasmic reticulum (ER) export carriers. Rings of TANGO1 surround COPII, implicating TANGO1 in organizing ER exit sites and in regulating COPII coat dynamics and geometry.
April 3, 2017: Journal of Cell Biology
https://www.readbyqxmd.com/read/28287860/autophagosome-formation-where-the-secretory-and-autophagy-pathways-meet
#18
Juan Wang, Saralin Davis, Ming Zhu, Elizabeth A Miller, Susan Ferro-Novick
The upregulation of autophagosome formation in response to nutrient deprivation requires significant intracellular membrane rearrangements that are poorly understood. Recent findings have implicated COPII-coated vesicles, well known as ER-Golgi cargo transport carriers, as key players in macroautophagy. The role of COPII vesicles in macroautophagy and how they interact with autophagy-related (Atg) proteins was unknown. In our recent report, we show that during nutrient deprivation, phosphorylation of the membrane-distal surface of the COPII coat subunit Sec24 facilitates the interaction of Sec24 with the Atg machinery (specifically, Atg9) to regulate the abundance of autophagosomes during starvation...
May 4, 2017: Autophagy
https://www.readbyqxmd.com/read/28280122/tango1-spatially-organizes-er-exit-sites-to-control-er-export
#19
Min Liu, Zhi Feng, Hongmei Ke, Ying Liu, Tianhui Sun, Jianli Dai, Wenhong Cui, José Carlos Pastor-Pareja
Exit of secretory cargo from the endoplasmic reticulum (ER) takes place at specialized domains called ER exit sites (ERESs). In mammals, loss of TANGO1 and other MIA/cTAGE (melanoma inhibitory activity/cutaneous T cell lymphoma-associated antigen) family proteins prevents ER exit of large cargoes such as collagen. Here, we show that Drosophila melanogaster Tango1, the only MIA/cTAGE family member in fruit flies, is a critical organizer of the ERES-Golgi interface. Tango1 rings hold COPII (coat protein II) carriers and Golgi in close proximity at their center...
April 3, 2017: Journal of Cell Biology
https://www.readbyqxmd.com/read/28280121/tango1-assembles-into-rings-around-copii-coats-at-er-exit-sites
#20
Ishier Raote, Maria Ortega Bellido, Marinella Pirozzi, Chong Zhang, David Melville, Seetharaman Parashuraman, Timo Zimmermann, Vivek Malhotra
TANGO1 (transport and Golgi organization 1) interacts with CTAGE5 and COPII components Sec23/Sec24 and recruits ERGIC-53 (endoplasmic reticulum [ER]-Golgi intermediate compartment 53)-containing membranes to generate a mega-transport carrier for export of collagens and apolipoproteins from the ER. We now show that TANGO1, at the ER, assembles in a ring that encircles COPII components. The C-terminal, proline-rich domains of TANGO1 molecules in the ring are initially tilted onto COPII coats but appear to be pushed apart as the carrier grows...
April 3, 2017: Journal of Cell Biology
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