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Michael G Hanna, Jennifer L Peotter, E B Frankel, Anjon Audhya
Most metazoan organisms have evolved a mildly acidified and calcium diminished sorting hub in the early secretory pathway commonly referred to as the Endoplasmic Reticulum-Golgi intermediate compartment (ERGIC). These membranous vesicular-tubular clusters are found tightly juxtaposed to ER subdomains that are competent for the production of COPII-coated transport carriers. In contrast to many unicellular systems, metazoan COPII carriers largely transit just a few hundred nanometers to the ERGIC, prior to COPI-dependent transport on to the cis-Golgi...
May 9, 2018: BioEssays: News and Reviews in Molecular, Cellular and Developmental Biology
Takuya Kiyohara, Kei Miyano, Sachiko Kamakura, Junya Hayase, Kanako Chishiki, Akira Kohda, Hideki Sumimoto
Transmembrane glycoproteins, synthesized at the endoplasmic reticulum (ER), generally reach the Golgi apparatus in COPII-coated vesicles en route to the cell surface. Here, we show that the bona fide nonglycoprotein Nox5, a transmembrane superoxide-producing NADPH oxidase, is transported to the cell surface in a manner resistant to co-expression of Sar1 (H79G), a GTP-fixed mutant of the small GTPase Sar1, which blocks COPII vesicle fission from the ER. In contrast, Sar1 (H79G) effectively inhibits ER-to-Golgi transport of glycoproteins including the Nox5-related oxidase Nox2...
May 2, 2018: Genes to Cells: Devoted to Molecular & Cellular Mechanisms
Keiko Saegusa, Miyuki Sato, Nobukatsu Morooka, Taichi Hara, Ken Sato
Lipoproteins regulate the overall lipid homeostasis in animals. However, the molecular mechanisms underlying lipoprotein trafficking remain poorly understood. Here, we show that SFT-4, a Caenorhabditis elegans homologue of the yeast Erv29p, is essential for the endoplasmic reticulum (ER) export of the yolk protein VIT-2, which is synthesized as a lipoprotein complex. SFT-4 loss strongly inhibits the ER exit of yolk proteins and certain soluble cargo proteins in intestinal cells. SFT-4 predominantly localizes at ER exit sites (ERES) and physically interacts with VIT-2 in vivo, which suggests that SFT-4 promotes the ER export of soluble proteins as a cargo receptor...
April 11, 2018: Journal of Cell Biology
Nopprarat Tongmuang, Umpa Yasamut, Pucharee Songprakhon, Thanyaporn Dechtawewat, Shilu Malakar, Sansanee Noisakran, Pa-Thai Yenchitsomanus, Thawornchai Limjindaporn
Dengue hemorrhagic fever is a life-threatening disease caused by the dengue virus (DENV). After DENV enters into host cells, it replicates to generate viral particles to infect other cells. DENV exploits components of the cellular trafficking pathway to achieve effective virion production. Understanding of the proteins required for this trafficking process is essential for revealing the pathogenesis of DENV infection. Coat protein complex and soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs), two host protein families in the cellular trafficking pathway, were investigated to elucidate their respective roles during DENV infection...
March 30, 2018: Virus Research
Kohei Kawaguchi, Akinori Endo, Toshiaki Fukushima, Yuka Madoka, Toshiaki Tanaka, Masayuki Komada
Nascent cargo proteins in the endoplasmic reticulum are transported to the Golgi by COPII carriers. Typical COPII vesicles are 60-70 nm in diameter, and much larger macromolecules, such as procollagen, are transported by atypical large COPII carriers in mammalian cells. The formation of large COPII carriers is enhanced by Cul3 ubiquitin ligase, which mono-ubiquitinates Sec31A, a COPII coat protein. However, the deubiquitinating enzyme for Sec31A was unclear. Here, we show that the deubiquitinating enzyme USP8 interacts with and deubiquitinates Sec31A...
March 28, 2018: Biochemical and Biophysical Research Communications
Edith Uetz-von Allmen, Alexandra V Rippl, Hesso Farhan, Daniel F Legler
Chemokine receptors are considered to belong to the group of G protein-coupled receptors that use the first transmembrane domain as signal anchor sequence for membrane insertion instead of a cleavable N-terminal signal sequence. Chemokine recognition is determined by the N-termini of chemokine receptors. Here, we show that the chemokine receptor CCR7, which is essential for directed migration of adaptive immune cells, possesses a 24 amino acids long N-terminal signal sequence that is unique among chemokine receptors...
March 30, 2018: Journal of Leukocyte Biology
Chao Nie, Huimin Wang, Rui Wang, David Ginsburg, Xiao-Wei Chen
The flow of cargo vesicles along the secretory pathway requires concerted action among various regulators. The COPII complex, assembled by the activated SAR1 GTPases on the surface of the endoplasmic reticulum, orchestrates protein interactions to package cargos and generate transport vesicles en route to the Golgi. The dynamic nature of COPII, however, hinders analysis with conventional biochemical assays. Here we apply proximity-dependent biotinylation labeling to capture the dynamics of COPII transport in cells...
April 3, 2018: Proceedings of the National Academy of Sciences of the United States of America
Joseph E Pick, Edward B Ziff
A fundamental property of the brain is its ability to modify its function in response to its own activity. This ability for self-modification depends to a large extent on synaptic plasticity. It is now appreciated that for excitatory synapses, a significant part of synaptic plasticity depends upon changes in the post synaptic response to glutamate released from nerve terminals. Modification of the post synaptic response depends, in turn, on changes in the abundances of AMPA receptors in the post synaptic membrane...
March 12, 2018: Molecular and Cellular Neurosciences
Ishier Raote, Maria Ortega-Bellido, António Jm Santos, Ombretta Foresti, Chong Zhang, Maria F Garcia-Parajo, Felix Campelo, Vivek Malhotra
Collagen export from the endoplasmic reticulum (ER) requires TANGO1, COPII coats, and retrograde fusion of ERGIC membranes. How do these components come together to produce a transport carrier commensurate with the bulky cargo collagen? TANGO1 is known to form a ring that corrals COPII coats, and we show here how this ring or fence is assembled. Our data reveal that a TANGO1 ring is organized by its radial interaction with COPII, and lateral interactions with cTAGE5, TANGO1-short or itself. Of particular interest is the finding that TANGO1 recruits ERGIC membranes for collagen export via the NRZ (<u>N</u>BAS/<u>R</u>INT1/<u>Z</u>W10) tether complex...
March 7, 2018: ELife
David Cruz-Garcia, Vivek Malhotra, Amy J Curwin
It is usually assumed that eukaryotic cells secrete only proteins that contain a signal sequence for Sec61 mediated translocation into the lumen of endoplasmic reticulum (ER). Surprisingly however, many proteins, such as superoxide dismutase (SOD)1, acyl-CoA binding protein (Acb1), interleukin 1β, fibroblast growth factor 2 and the adipokine Unpaired2, to name a few, are secreted even though they lack a signal sequence. The discovery that these proteins are secreted has presented a new challenge and we describe here a common pathway by which SOD1 and Acb1 are specifically secreted upon nutrient starvation...
February 28, 2018: Seminars in Cell & Developmental Biology
Susan Patalano, José Rodríguez-Nieves, Cory Colaneri, Justin Cotellessa, Diego Almanza, Alisa Zhilin-Roth, Todd Riley, Jill Macoska
Tissue fibrosis is mediated by the actions of multiple pro-fibrotic proteins that can induce myofibroblast phenoconversion through diverse signaling pathways coupled predominantly to Smads or MEK/Erk proteins. The TGFβ/TGFβR and CXCL12/CXCR4 axes induce myofibroblast phenoconversion independently through Smads and MEK/Erk proteins, respectively. To investigate these mechanisms at the genetic level, we have now elucidated the TGFβ/TGFβR and CXCL12/CXCR4 transcriptomes in human fibroblasts. These transcriptomes are largely convergent, and up-regulate transcripts encoding proteins known to promote myofibroblast phenoconversion...
February 22, 2018: Scientific Reports
Yan Wang, Zhi Chai, Min Wang, Yanling Jin, Aijun Yang, Min Li
Coat proteins (COPs), including the major types clathrin, COPI and COPII, play a considerable role in intracellular transport by initiating the formation of transport vesicles. Coatomer protein complex subunit β2 (COPB2) is one of the seven subunits that make up a COPI complex. In the present study, we found that COPB2 was highly expressed in human colon cancer specimens. However, to date, there have been no reports describing the functions of COPB2 in human colon cancer cells. In this study, we analyzed the functions of COPB2 in the proliferation and cell cycle arrest of human RKO and HCT116 colon cancer cells by using lentivirus-mediated RNAi infection...
January 2018: Experimental and Therapeutic Medicine
Mostafa Aboulela, Tsuyoshi Nakagawa, Akinobu Oshima, Kohji Nishimura, Yuji Tanaka
The specialized multilayered pollen wall plays multiple roles to ensure normal microspore development. The major components of the pollen wall (e.g. sporopollenin and lipidic precursors) are provided from the tapetum. Material export from the endoplasmic reticulum (ER) is mediated by coat protein complex II (COPII) vesicles. The Arabidopsis thaliana genome encodes seven homologs of SEC23, a COPII component. However, the functional importance of this diversity remains elusive. Here, we analyzed knockout and knockdown lines for AtSEC23A and AtSEC23D, two of the A...
March 24, 2018: Journal of Experimental Botany
(no author information available yet)
First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Yoko Ito is the first author on 'The Golgi entry core compartment functions as a COPII-independent scaffold for ER-to-Golgi transport in plant cells', published in Journal of Cell Science. Yoko is a postdoctoral researcher in the Live Cell Super-Resolution Imaging Research Team in the lab of Akihiko Nakano at the RIKEN Center for Advanced Photonics, Wako, Saitama, Japan...
January 29, 2018: Journal of Cell Science
Min Zhang, Yu Wang, Liang Ge
Autophagosomal membrane sources generate autophagic membrane precursors, which later assemble into the double-membrane autophagosome. The key events happening on the membrane sources during autophagic membrane generation remain poorly characterized. Our previous work found the ER-Golgi intermediate compartment (ERGIC) as a membrane source for the phagophore, the precursor to the autophagosome. A relocation of the COPII machinery from the ER-exit sites (ERES) to the ERGIC generates vesicles for LC3 lipidation...
January 25, 2018: Autophagy
Julien Béthune, Felix T Wieland
In eukaryotes, distinct transport vesicles functionally connect various intracellular compartments. These carriers mediate transport of membranes for the biogenesis and maintenance of organelles, secretion of cargo proteins and peptides, and uptake of cargo into the cell. Transport vesicles have distinct protein coats that assemble on a donor membrane where they can select cargo and curve the membrane to form a bud. A multitude of structural elements of coat proteins have been solved by X-ray crystallography...
January 18, 2018: Annual Review of Biophysics
Yan Wu, Xiao Peng Guo, Soshi Kanemoto, Yujiro Maeoka, Atsushi Saito, Rie Asada, Koji Matsuhisa, Yosuke Ohtake, Kazunori Imaizumi, Masayuki Kaneko
We identified 37 ubiquitin ligases containing RING-finger and transmembrane domains. Of these, we found that RNF183 is abundantly expressed in the kidney. RNF183 predominantly localizes to the endoplasmic reticulum (ER), Golgi, and lysosome. We identified Sec16A, which is involved in coat protein complex II vesicle formation, as an RNF183-interacting protein. RNF183 colocalized with Sec16A and interacted through the central conserved domain (CCD) of Sec16A. Although Sec16A is not a substrate for RNF183, RNF183 was more rapidly degraded by the ER-associated degradation (ERAD) in the absence of Sec16A...
2018: PloS One
Lin Yuan, Satoshi Baba, Kanika Bajaj, Randy Schekman
The aim of this protocol is to generate COPII-coated procollagen I (PC1) carriers in a cell-free reaction. The COPII-coated PC1 carriers were reconstituted from donor membrane, cytosol, purified recombinant COPII proteins, and nucleotides. This protocol describes the preparation of donor membrane and cytosol, the assembly of the reaction, and the isolation and detection of reconstituted COPII-coated carriers. This cell-free reaction can be used to test conditions that stimulate or suppress the packaging of PC1 into COPII-coated carriers...
November 20, 2017: Bio-protocol
Nathan J Cox, Gokhan Unlu, Brittany J Bisnett, Thomas R Meister, Brett M Condon, Peter M Luo, Timothy J Smith, Michael Hanna, Abhishek Chhetri, Erik J Soderblom, Anjon Audhya, Ela W Knapik, Michael Boyce
The COPII coat complex, which mediates secretory cargo trafficking from the endoplasmic reticulum, is a key control point for subcellular protein targeting. Because misdirected proteins cannot function, protein sorting by COPII is critical for establishing and maintaining normal cell and tissue homeostasis. Indeed, mutations in COPII genes cause a range of human pathologies, including cranio-lenticulo-sutural dysplasia (CLSD), which is characterized by collagen trafficking defects, craniofacial abnormalities, and skeletal dysmorphology...
January 9, 2018: Biochemistry
Junwan Fan, Yaqing Wang, Liang Liu, Hongsheng Zhang, Feng Zhang, Lei Shi, Mei Yu, Fei Gao, Zhiheng Xu
Proinsulin is synthesized in the endoplasmic reticulum (ER) in pancreatic β cells and transported to the Golgi apparatus for proper processing and secretion into plasma. Defects in insulin biogenesis may cause diabetes. However, the underlying mechanisms for proinsulin transport are still not fully understood. We show that β cell-specific deletion of cTAGE5 , also known as Mea6 , leads to increased ER stress, reduced insulin biogenesis in the pancreas, and severe glucose intolerance in mice. We reveal that cTAGE5/MEA6 interacts with vesicle membrane soluble N -ethyl-maleimide sensitive factor attachment protein receptor Sec22b...
December 4, 2017: Journal of Cell Biology
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