scholarly journals Cell Cycle-dependent Changes in Localization and Phosphorylation of the Plasma Membrane Kv2.1 K+Channel Impact Endoplasmic Reticulum Membrane Contact Sites in COS-1 Cells

2015 ◽  
Vol 290 (49) ◽  
pp. 29189-29201 ◽  
Author(s):  
Melanie M. Cobb ◽  
Daniel C. Austin ◽  
Jon T. Sack ◽  
James S. Trimmer
Keyword(s):  
Cell Cycle ◽  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
K Channel ◽  
Endoplasmic Reticulum Membrane ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Contact ◽  
Cycle Dependent

scholarly journals Remodeling of ER–plasma membrane contact sites but not STIM1 phosphorylation inhibits Ca2+influx in mitosis

2019 ◽  
Vol 116 (21) ◽  
pp. 10392-10401 ◽  
Author(s):  
Fang Yu ◽  
Satanay Z. Hubrack ◽  
Sumita Chakraborty ◽  
Lu Sun ◽  
Ethel Alcantara-Adap ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Cell Cycle Progression ◽  
Mechanistic Explanation ◽  
Cycle Progression ◽  
Protein Levels ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Contact

Store-operated Ca2+entry (SOCE), mediated by the endoplasmic reticulum (ER) Ca2+sensor stromal interaction molecule 1 (STIM1) and the plasma membrane (PM) channel Orai1, is inhibited during mitosis. STIM1 phosphorylation has been suggested to mediate this inhibition, but it is unclear whether additional pathways are involved. Here, we demonstrate using various approaches, including a nonphosphorylatable STIM1 knock-in mouse, that STIM1 phosphorylation is not required for SOCE inhibition in mitosis. Rather, multiple pathways converge to inhibit Ca2+influx in mitosis. STIM1 interacts with the cochaperone BAG3 and localizes to autophagosomes in mitosis, and STIM1 protein levels are reduced. The density of ER–PM contact sites (CSs) is also dramatically reduced in mitosis, thus physically preventing STIM1 and Orai1 from interacting to activate SOCE. Our findings provide insights into ER–PM CS remodeling during mitosis and a mechanistic explanation of the inhibition of Ca2+influx that is required for cell cycle progression.

scholarly journals Synaptotagmins at the endoplasmic reticulum–plasma membrane contact sites maintain diacylglycerol homeostasis during abiotic stress

2021 ◽  
Author(s):  
Noemi Ruiz-Lopez ◽  
Jessica Pérez-Sancho ◽  
Alicia Esteban del Valle ◽  
Richard P Haslam ◽  
Steffen Vanneste ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Abiotic Stress ◽  
Fluorescent Protein ◽  
Mechanical Damage ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Contact ◽  
Green Fluorescent

Abstract Endoplasmic reticulum-plasma membrane contact sites (ER-PM CS) play fundamental roles in all eukaryotic cells. Arabidopsis thaliana mutants lacking the ER-PM protein tether synaptotagmin1 (SYT1) exhibit decreased plasma membrane (PM) integrity under multiple abiotic stresses such as freezing, high salt, osmotic stress and mechanical damage. Here, we show that, together with SYT1, the stress-induced SYT3 is an ER-PM tether that also functions in maintaining PM integrity. The ER-PM CS localization of SYT1 and SYT3 is dependent on PM phosphatidylinositol-4-phosphate and is regulated by abiotic stress. Lipidomic analysis revealed that cold stress increased the accumulation of diacylglycerol at the PM in a syt1/3 double mutant relative to wild type while the levels of most glycerolipid species remain unchanged. Additionally, the SYT1-green fluorescent protein (GFP) fusion preferentially binds diacylglycerol in vivo with little affinity for polar glycerolipids. Our work uncovers a SYT-dependent mechanism of stress adaptation counteracting the detrimental accumulation of diacylglycerol at the PM produced during episodes of abiotic stress.

scholarly journals Kv2 potassium channels form endoplasmic reticulum/plasma membrane junctions via interaction with VAPA and VAPB

2018 ◽  
Vol 115 (31) ◽  
pp. E7331-E7340 ◽  
Author(s):  
Ben Johnson ◽  
Ashley N. Leek ◽  
Laura Solé ◽  
Emily E. Maverick ◽  
Tim P. Levine ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Membrane Trafficking ◽  
Neuronal Cultures ◽  
Physical Relationship ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Hek Cells ◽  
C Terminus ◽  
Membrane Contact

Kv2.1 exhibits two distinct forms of localization patterns on the neuronal plasma membrane: One population is freely diffusive and regulates electrical activity via voltage-dependent K+ conductance while a second one localizes to micrometer-sized clusters that contain densely packed, but nonconducting, channels. We have previously established that these clusters represent endoplasmic reticulum/plasma membrane (ER/PM) junctions that function as membrane trafficking hubs and that Kv2.1 plays a structural role in forming these membrane contact sites in both primary neuronal cultures and transfected HEK cells. Clustering and the formation of ER/PM contacts are regulated by phosphorylation within the channel C terminus, offering cells fast, dynamic control over the physical relationship between the cortical ER and PM. The present study addresses the mechanisms by which Kv2.1 and the related Kv2.2 channel interact with the ER membrane. Using proximity-based biotinylation techniques in transfected HEK cells we identified ER VAMP-associated proteins (VAPs) as potential Kv2.1 interactors. Confirmation that Kv2.1 and -2.2 bind VAPA and VAPB employed colocalization/redistribution, siRNA knockdown, and Förster resonance energy transfer (FRET)-based assays. CD4 chimeras containing sequence from the Kv2.1 C terminus were used to identify a noncanonical VAP-binding motif. VAPs were first identified as proteins required for neurotransmitter release in Aplysia and are now known to be abundant scaffolding proteins involved in membrane contact site formation throughout the ER. The VAP interactome includes AKAPs, kinases, membrane trafficking machinery, and proteins regulating nonvesicular lipid transport from the ER to the PM. Therefore, the Kv2-induced VAP concentration at ER/PM contact sites is predicted to have wide-ranging effects on neuronal cell biology.

scholarly journals Synaptotagmin-Associated Endoplasmic Reticulum-Plasma Membrane Contact Sites Are Localized to Immobile ER Tubules

2018 ◽  
Vol 178 (2) ◽  
pp. 641-653 ◽  
Author(s):  
Kazuya Ishikawa ◽  
Kentaro Tamura ◽  
Haruko Ueda ◽  
Yoko Ito ◽  
Akihiko Nakano ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Contact

Mitochondria–organelle contact sites: the plot thickens

2017 ◽  
Vol 45 (2) ◽  
pp. 477-488 ◽  
Author(s):  
Yael Elbaz-Alon
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Cellular Metabolism ◽  
Close Apposition ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Contact ◽  
Cellular Organelles

Membrane contact sites (MCSs) are areas of close apposition between the membranes of two different organelles that enable non-vesicular transfer of ions and lipids. Recent studies reveal that mitochondria maintain contact sites with organelles other than the endoplasmic reticulum such as the vacuole, plasma membrane and peroxisomes. This review focuses on novel findings achieved mainly in yeast regarding tethers, function and regulation of mitochondria–organelle contact sites. The emerging network of MCSs linking virtually all cellular organelles is highly dynamic and integrated with cellular metabolism.

scholarly journals Synaptotagmins Maintain Diacylglycerol Homeostasis at Endoplasmic Reticulum-Plasma Membrane Contact Sites during Abiotic Stress

2020 ◽  
Author(s):  
Noemi Ruiz-Lopez ◽  
Jessica Pérez-Sancho ◽  
Alicia Esteban del Valle ◽  
Richard P. Haslam ◽  
Steffen Vanneste ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Abiotic Stress ◽  
Mechanical Damage ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Contact ◽  
Phosphatidylinositol 4 ◽  
Polar Glycerolipids

SUMMARYEndoplasmic Reticulum-Plasma Membrane contact sites (ER-PM CS) play fundamental roles in all eukaryotic cells. Arabidopsis mutants lacking the ER-PM protein tether synaptotagmin1 (SYT1) exhibit decreased plasma membrane (PM) integrity under multiple abiotic stresses such as freezing, high salt, osmotic stress and mechanical damage. Here, we show that, together with SYT1, the stress-induced SYT3 is an ER-PM tether that also functions in maintaining PM integrity. The ER-PM CS localization of SYT1 and SYT3 is dependent on PM phosphatidylinositol-4-phosphate and is regulated by abiotic stress. Lipidomic analysis revealed that cold stress increased the accumulation of diacylglycerol at the PM in a syt1/3 double mutant relative to WT while the levels of most glycerolipid species remain unchanged. Additionally, SYT1-GFP preferentially binds diacylglycerol in vivo with little affinity for polar glycerolipids. Our work uncovers a crucial SYT-dependent mechanism of stress adaptation counteracting the detrimental accumulation of diacylglycerol at the PM produced during episodes of abiotic stress.

scholarly journals Endoplasmic reticulum-plasma membrane contact sites integrate sterol and phospholipid regulation

PLoS Biology ◽  
2018 ◽  
Vol 16 (5) ◽  
pp. e2003864 ◽  
Author(s):  
Evan Quon ◽  
Yves Y. Sere ◽  
Neha Chauhan ◽  
Jesper Johansen ◽  
David P. Sullivan ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Contact
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