scholarly journals Annexin A1 Tethers Membrane Contact Sites that Mediate ER to Endosome Cholesterol Transport

2016 ◽  
Vol 37 (5) ◽  
pp. 473-483 ◽  
Author(s):  
Emily R. Eden ◽  
Elena Sanchez-Heras ◽  
Anna Tsapara ◽  
Andrzej Sobota ◽  
Tim P. Levine ◽  
...  
Keyword(s):  
Cholesterol Transport ◽  
Annexin A1 ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Contact

scholarly journals STARD 3 mediates endoplasmic reticulum‐to‐endosome cholesterol transport at membrane contact sites

2017 ◽  
Vol 36 (10) ◽  
pp. 1412-1433 ◽  
Author(s):  
Léa P Wilhelm ◽  
Corinne Wendling ◽  
Benoît Védie ◽  
Toshihide Kobayashi ◽  
Marie‐Pierre Chenard ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cholesterol Transport ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Contact

Oxysterol binding proteins: in more than one place at one time?

2004 ◽  
Vol 82 (1) ◽  
pp. 87-98 ◽  
Author(s):  
Vesa M Olkkonen ◽  
Timothy P Levine
Keyword(s):  
Cholesterol Transport ◽  
Liver X Receptors ◽  
Oxysterol Binding Protein ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Expression Of Genes ◽  
Interaction Partners ◽  
Membrane Contact ◽  
X Receptors ◽  
Related Proteins

Oxysterols are potent signalling lipids that directly bind liver X receptors (LXRs) and a subset of oxysterol binding protein (OSBP) related proteins (ORPs). It is relatively well established that the oxysterol-regulated function of LXRs is to control the expression of genes involved in reverse cholesterol transport, catabolism of cholesterol, and lipogenesis. In contrast, the mechanisms by which oxysterols and ORPs affect cellular lipid metabolism have remained poorly understood. In this review, we summarize the information available on function of the ORPs and compare the two families of proteins binding oxysterol to demonstrate the different responses that similar lipids can elicit within cells. The other focus is on the membrane targeting determinants and the protein interaction partners of ORPs, which provide interesting clues to the mode(s) of ORP action. Specifically, we suggest a model in which a general property of ORPs is to function at membrane contact sites, specialized zones of communication between two different organelles.Key words: endoplasmic reticulum, lipid transport, LXR, membrane contact sites, ORP, OSBP, Osh, sterol metabolism.

scholarly journals Caenorhabditis elegans Junctophilin has tissue-specific functions and regulates neurotransmission with extended-synaptotagmin

Genetics ◽  
2021 ◽  
Author(s):  
Christopher A Piggott ◽  
Zilu Wu ◽  
Stephen Nurrish ◽  
Suhong Xu ◽  
Joshua M Kaplan ◽  
...  
Keyword(s):  
Calcium Channels ◽  
Calcium Channel ◽  
Tissue Specific ◽  
Voltage Gated ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Pharyngeal Muscles ◽  
Membrane Contact ◽  
Null Mutants

Abstract The junctophilin family of proteins tether together plasma membrane (PM) and endoplasmic reticulum (ER) membranes, and couple PM- and ER-localized calcium channels. Understanding in vivo functions of junctophilins is of great interest for dissecting the physiological roles of ER-PM contact sites. Here, we show that the sole C. elegans junctophilin JPH-1 localizes to discrete membrane contact sites in neurons and muscles and has important tissue-specific functions. jph-1 null mutants display slow growth and development due to weaker contraction of pharyngeal muscles, leading to reduced feeding. In the body wall muscle, JPH-1 co-localizes with the PM-localized EGL-19 voltage-gated calcium channel and ER-localized UNC-68/RyR calcium channel, and is required for animal movement. In neurons, JPH-1 co-localizes with the membrane contact site protein Extended-SYnaptoTagmin 2 (ESYT-2) in soma, and is present near presynaptic release sites. Interestingly, jph-1 and esyt-2 null mutants display mutual suppression in their response to aldicarb, suggesting that JPH-1 and ESYT-2 have antagonistic roles in neuromuscular synaptic transmission. Additionally, we find an unexpected cell non-autonomous effect of jph-1 in axon regrowth after injury. Genetic double mutant analysis suggests that jph-1 functions in overlapping pathways with two PM-localized voltage-gated calcium channels, egl-19 and unc-2, and unc-68/RyR for animal health and development. Finally, we show that jph-1 regulates the colocalization of EGL-19 and UNC-68 and that unc-68/RyR is required for JPH-1 localization to ER-PM puncta. Our data demonstrate important roles for junctophilin in cellular physiology, and also provide insights into how junctophilin functions together with other calcium channels in vivo.

scholarly journals Remodelling of Nucleus-Vacuole Junctions During Metabolic and Proteostatic Stress

Contact ◽  
2021 ◽  
Vol 4 ◽  
pp. 251525642110166
Author(s):  
Verena Kohler ◽  
Sabrina Büttner
Keyword(s):  
Nuclear Envelope ◽  
Internal Stress ◽  
Molecular Architecture ◽  
Adaptation To Stress ◽  
Semipermeable Membranes ◽  
Cellular Adaptation ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Intracellular Compartments ◽  
Membrane Contact

Cellular adaptation to stress and metabolic cues requires a coordinated response of different intracellular compartments, separated by semipermeable membranes. One way to facilitate interorganellar communication is via membrane contact sites, physical bridges between opposing organellar membranes formed by an array of tethering machineries. These contact sites are highly dynamic and establish an interconnected organellar network able to quickly respond to external and internal stress by changing size, abundance and molecular architecture. Here, we discuss recent work on nucleus-vacuole junctions, connecting yeast vacuoles with the nucleus. Appearing as small, single foci in mitotic cells, these contacts expand into one enlarged patch upon nutrient exhaustion and entry into quiescence or can be shaped into multiple large foci essential to sustain viability upon proteostatic stress at the nuclear envelope. We highlight the remarkable plasticity and rapid remodelling of these contact sites upon metabolic or proteostatic stress and their emerging importance for cellular fitness.

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