scholarly journals Incredibly close—A newly identified peroxisome–ER contact site in humans

2017 ◽  
Vol 216 (2) ◽  
pp. 287-289 ◽  
Author(s):  
Maya Schuldiner ◽  
Einat Zalckvar
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Protein ◽  
Binding Protein ◽  
Human Cells ◽  
Metabolic Processes ◽  
Contact Site ◽  
Cell Biol ◽  
Associated Proteins

Peroxisomes are tiny organelles that control important and diverse metabolic processes via their interplay with other organelles, including the endoplasmic reticulum (ER). In this issue, Costello et al. (2017. J. Cell Biol. https://doi.org/10.1083/jcb.201607055) and Hua et al. (2017. J. Cell Biol. https://doi.org/10.1083/jcb.201608128) identify a peroxisome–ER contact site in human cells held together by a tethering complex of VAPA/B (vesicle-associated membrane protein–associated proteins A/B) and ACBD5 (acyl Co-A binding protein 5).

Isoflurane Preconditions Hippocampal Neurons against Oxygen–Glucose Deprivation

2005 ◽  
Vol 103 (3) ◽  
pp. 532-539 ◽  
Author(s):  
Philip E. Bickler ◽  
Xinhua Zhan ◽  
Christian S. Fahlman
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Kinase ◽  
Hippocampal Slice ◽  
Binding Protein ◽  
Glucose Deprivation ◽  
Mitogen Activated Protein Kinase ◽  
Oxygen Glucose Deprivation ◽  
Hippocampal Slice Cultures ◽  
Mitogen Activated Protein ◽  
Associated Proteins

Background Isoflurane preconditions neurons to improve tolerance of subsequent ischemia in both intact animal models and in in vitro preparations. The mechanisms for this protection remain largely undefined. Because isoflurane increases intracellular Ca2+ concentrations and Ca2+ is involved in many processes related to preconditioning, the authors hypothesized that isoflurane preconditions neurons via Ca2+-dependent processes involving the Ca2+- binding protein calmodulin and the mitogen-activated protein kinase-ERK pathway. Methods The authors used a preconditioning model in which organotypic cultures of rat hippocampus were exposed to 0.5-1.5% isoflurane for a 2-h period 24 h before an ischemia-like injury of oxygen-glucose deprivation. Survival of CA1, CA3, and dentate neurons was assessed 48 later, along with interval measurements of intracellular Ca2+ concentration (fura-2 fluorescence microscopy in CA1 neurons), mitogen-activated protein kinase p42/44, and the survival associated proteins Akt and GSK-3beta (in situ immunostaining and Western blots). Results Preconditioning with 0.5-1.5% isoflurane decreased neuron death in CA1 and CA3 regions of hippocampal slice cultures after oxygen-glucose deprivation. The preconditioning period was associated with an increase in basal intracellular Ca2+ concentration of 7-15%, which involved Ca2+ release from inositol triphosphate-sensitive stores in the endoplasmic reticulum, and transient phosphorylation of mitogen-activated protein kinase p42/44 and the survival-associated proteins Akt and GSK-3beta. Preconditioning protection was eliminated by the mitogen-activated extracellular kinase inhibitor U0126, which prevented phosphorylation of p44 during preconditioning, and by calmidazolium, which antagonizes the effects of Ca2+-bound calmodulin. Conclusions Isoflurane, at clinical concentrations, preconditions neurons in hippocampal slice cultures by mechanisms that apparently involve release of Ca2+ from the endoplasmic reticulum, transient increases in intracellular Ca2+ concentration, the Ca2+ binding protein calmodulin, and phosphorylation of the mitogen-activated protein kinase p42/44.

scholarly journals Inhibition of adipogenesis: a new job for the ER Ca2+ pool

2008 ◽  
Vol 182 (1) ◽  
pp. 11-13 ◽  
Author(s):  
Jacopo Meldolesi
Keyword(s):  
Endoplasmic Reticulum ◽  
Binding Protein ◽  
Endoplasmic Reticulum Lumen ◽  
Cell Biol ◽  
Multipotent Cells

Adipogenesis is the process of differentiation of adipocytes from mesenchymal multipotent cells through adipocyte precursors. In this issue, a study by the groups of Opas and Michalak (Szabo, E., Y. Qiu, S. Baksh, M. Michalak, and M. Opas. 2008. J. Cell. Biol. 182:103–116) demonstrates that this process is repressed by increasing intracellular Ca2+, which, in turn, is dependent on the expression of calreticulin, the major Ca2+-binding protein of the endoplasmic reticulum lumen.

scholarly journals Making Contact: VAP Targeting by Intracellular Pathogens

Contact ◽  
2018 ◽  
Vol 1 ◽  
pp. 251525641877551
Author(s):  
Rebecca Stanhope ◽  
Isabelle Derré
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Protein ◽  
Molecular Mimicry ◽  
Intracellular Pathogens ◽  
Inclusion Membrane ◽  
Host Pathogen Interaction ◽  
Host Pathogen ◽  
Associated Proteins ◽  
Membrane Contacts ◽  
Common Components

In naïve cells, the endoplasmic reticulum (ER) and the ER-resident Vesicle-associated membrane protein- Associated Proteins (VAP) are common components of sites of membrane contacts that mediate the nonvesicular transfer of lipids between organelles. There is increasing recognition that the hijacking of VAP by intracellular pathogens is a novel mechanism of host–pathogen interaction. Here, we summarize our recent findings showing that the Chlamydia inclusion membrane protein IncV tethers the ER to the inclusion membrane by binding to VAP via the molecular mimicry of two eukaryotic FFAT motifs. We extend the discussion to other microorganisms that have evolved similar mechanisms.

scholarly journals Getting a handle on lipid droplets: Insights into ER–lipid droplet tethering

2019 ◽  
Vol 218 (4) ◽  
pp. 1089-1091 ◽  
Author(s):  
Truc B. Nguyen ◽  
James A. Olzmann
Keyword(s):  
Endoplasmic Reticulum ◽  
Lipid Metabolism ◽  
Lipid Droplet ◽  
Lipid Droplets ◽  
Human Cells ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Cell Biol ◽  
Membrane Contact

Lipid droplets (LDs) are hubs for lipid metabolism that form membrane contact sites with multiple organelles. In this issue, Hariri et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201808119) reveal the functions of Mdm1-mediated endoplasmic reticulum (ER)–LD tethering in yeast and Datta et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201808133) identify a role for the Mdm1 orthologue, Snx14, as an ER–LD tether that regulates lipid metabolism in human cells.

scholarly journals Binding of lipopolysaccharide (LPS) to an 80-kilodalton membrane protein of human cells is mediated by soluble CD14 and LPS-binding protein.

1995 ◽  
Vol 63 (7) ◽  
pp. 2576-2580 ◽  
Author(s):  
J Schletter ◽  
H Brade ◽  
L Brade ◽  
C Krüger ◽  
H Loppnow ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Binding Protein ◽  
Human Cells ◽  
Soluble Cd14 ◽  
Lps Binding

scholarly journals Unconventional secretion by autophagosome exocytosis

2010 ◽  
Vol 188 (4) ◽  
pp. 451-452 ◽  
Author(s):  
Suzanne R. Pfeffer
Keyword(s):  
Endoplasmic Reticulum ◽  
Coenzyme A ◽  
Signal Sequence ◽  
Binding Protein ◽  
Yeast Genetics ◽  
Medium Chain ◽  
Cell Biol ◽  
Chain Acyl ◽  
Unconventional Secretion ◽  
Acyl Coenzyme A

In this issue, Duran et al. (2010. J. Cell Biol. doi: 10.1083/jcb.200911154) and Manjithaya et al. (2010. J. Cell Biol. doi: 10.1083/jcb.200911149) use yeast genetics to reveal a role for autophagosome intermediates in the unconventional secretion of an acyl coenzyme A (CoA)–binding protein that lacks an endoplasmic reticulum signal sequence. Medium-chain acyl CoAs are also required and may be important for substrate routing to this pathway.

scholarly journals Vesicle-associated Membrane Protein-associated Protein-A (VAP-A) Interacts with the Oxysterol-binding Protein to Modify Export from the Endoplasmic Reticulum

2002 ◽  
Vol 277 (33) ◽  
pp. 29908-29918 ◽  
Author(s):  
Jessica P. Wyles ◽  
Christopher R. McMaster ◽  
Neale D. Ridgway
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Protein ◽  
Binding Protein ◽  
Protein A ◽  
Oxysterol Binding Protein

TMCC3 localizes at the three-way junctions for the proper tubular network of the endoplasmic reticulum

2019 ◽  
Vol 476 (21) ◽  
pp. 3241-3260
Author(s):  
Sindhu Wisesa ◽  
Yasunori Yamamoto ◽  
Toshiaki Sakisaka
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Mammalian Cells ◽  
Coiled Coil ◽  
Transmembrane Domains ◽  
Domain Family ◽  
Coiled Coil Domain ◽  
U2os Cells ◽  
Er Membrane

The tubular network of the endoplasmic reticulum (ER) is formed by connecting ER tubules through three-way junctions. Two classes of the conserved ER membrane proteins, atlastins and lunapark, have been shown to reside at the three-way junctions so far and be involved in the generation and stabilization of the three-way junctions. In this study, we report TMCC3 (transmembrane and coiled-coil domain family 3), a member of the TEX28 family, as another ER membrane protein that resides at the three-way junctions in mammalian cells. When the TEX28 family members were transfected into U2OS cells, TMCC3 specifically localized at the three-way junctions in the peripheral ER. TMCC3 bound to atlastins through the C-terminal transmembrane domains. A TMCC3 mutant lacking the N-terminal coiled-coil domain abolished localization to the three-way junctions, suggesting that TMCC3 localized independently of binding to atlastins. TMCC3 knockdown caused a decrease in the number of three-way junctions and expansion of ER sheets, leading to a reduction of the tubular ER network in U2OS cells. The TMCC3 knockdown phenotype was partially rescued by the overexpression of atlastin-2, suggesting that TMCC3 knockdown would decrease the activity of atlastins. These results indicate that TMCC3 localizes at the three-way junctions for the proper tubular ER network.

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