scholarly journals A firehose for phospholipids

2020 ◽  
Vol 219 (5) ◽  
Author(s):  
William A. Prinz ◽  
James H. Hurley
Keyword(s):  
Transport Proteins ◽  
Lipid Transport ◽  
Cellular Membranes ◽  
Contact Sites

All lipid transport proteins in eukaryotes are thought to shuttle lipids between cellular membranes. In this issue, Li et al. (2020. J. Cell Biol.https://doi.org/10.1083/jcb.202001161) show that Vps13 has a channel-like domain that may allow lipids to flow between closely apposed membranes at contact sites.

Coupled sterol synthesis and transport machineries at ER–endocytic contact sites

2021 ◽  
Vol 220 (10) ◽  
Author(s):  
Javier Encinar del Dedo ◽  
Isabel María Fernández-Golbano ◽  
Laura Pastor ◽  
Paula Meler ◽  
Cristina Ferrer-Orta ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Actin Polymerization ◽  
Sterol Synthesis ◽  
Biosynthetic Enzymes ◽  
Cellular Membranes ◽  
Contact Sites ◽  
Endocytic Machinery ◽  
Mother Cells

Sterols are unevenly distributed within cellular membranes. How their biosynthetic and transport machineries are organized to generate heterogeneity is largely unknown. We previously showed that the yeast sterol transporter Osh2 is recruited to endoplasmic reticulum (ER)–endocytic contacts to facilitate actin polymerization. We now find that a subset of sterol biosynthetic enzymes also localizes at these contacts and interacts with Osh2 and the endocytic machinery. Following the sterol dynamics, we show that Osh2 extracts sterols from these subdomains, which we name ERSESs (ER sterol exit sites). Further, we demonstrate that coupling of the sterol synthesis and transport machineries is required for endocytosis in mother cells, but not in daughters, where plasma membrane loading with accessible sterols and endocytosis are linked to secretion.

scholarly journals Miga-mediated endoplasmic reticulum–mitochondria contact sites regulate neuronal homeostasis

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Lingna Xu ◽  
Xi Wang ◽  
Jia Zhou ◽  
Yunyi Qiu ◽  
Weina Shang ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
Mitochondrial Dynamics ◽  
Molecular Organization ◽  
Lipid Transport ◽  
Cellular Processes ◽  
Contact Sites ◽  
Neuronal Homeostasis ◽  
Higher Eukaryotes ◽  
Lateral Sclerosis

Endoplasmic reticulum (ER)–mitochondria contact sites (ERMCSs) are crucial for multiple cellular processes such as calcium signaling, lipid transport, and mitochondrial dynamics. However, the molecular organization, functions, regulation of ERMCS, and the physiological roles of altered ERMCSs are not fully understood in higher eukaryotes. We found that Miga, a mitochondrion located protein, markedly increases ERMCSs and causes severe neurodegeneration upon overexpression in fly eyes. Miga interacts with an ER protein Vap33 through its FFAT-like motif and an amyotrophic lateral sclerosis (ALS) disease related Vap33 mutation considerably reduces its interaction with Miga. Multiple serine residues inside and near the Miga FFAT motif were phosphorylated, which is required for its interaction with Vap33 and Miga-mediated ERMCS formation. The interaction between Vap33 and Miga promoted further phosphorylation of upstream serine/threonine clusters, which fine-tuned Miga activity. Protein kinases CKI and CaMKII contribute to Miga hyperphosphorylation. MIGA2, encoded by the miga mammalian ortholog, has conserved functions in mammalian cells. We propose a model that shows Miga interacts with Vap33 to mediate ERMCSs and excessive ERMCSs lead to neurodegeneration.

scholarly journals PDZD8 mediates a Rab7-dependent interaction of the ER with late endosomes and lysosomes

2019 ◽  
Vol 116 (45) ◽  
pp. 22619-22623 ◽  
Author(s):  
Andrés Guillén-Samander ◽  
Xin Bian ◽  
Pietro De Camilli
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Protein ◽  
Hot Spots ◽  
Transport Proteins ◽  
Lipid Transport ◽  
Domain Family ◽  
Late Endosomes ◽  
Dependent Interaction

Contacts between the endoplasmic reticulum (ER) and other membranes are hot spots for protein-mediated lipid transport between the 2 adjacent bilayers. Compiling a molecular inventory of lipid transport proteins present at these sites is a premise to the elucidation of their function. Here we show that PDZD8, an intrinsic membrane protein of the ER with a lipid transport module of the SMP domain family, concentrates at contacts between the ER and late endosomes/lysosomes, where it interacts with GTP-Rab7. These findings suggest that PDZD8 may cooperate with other proteins that function at the ER–endo/lysosome interface in coordinating endocytic flow with lipid transport between endocytic membranes and the ER.

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