scholarly journals Jagunal is required for reorganizing the endoplasmic reticulum during Drosophila oogenesis

2007 ◽  
Vol 176 (7) ◽  
pp. 941-952 ◽  
Author(s):  
Sangil Lee ◽  
Lynn Cooley
Keyword(s):  
Endoplasmic Reticulum ◽  
Drosophila Melanogaster ◽  
Membrane Protein ◽  
Membrane Traffic ◽  
Protein Loss ◽  
Drosophila Oogenesis ◽  
Vesicular Traffic ◽  
Lateral Membrane ◽  
Evolutionarily Conserved ◽  
Er Membrane

Vesicular traffic in the Drosophila melanogaster oocyte occurs actively during vitellogenesis. Although endocytosis in the oocyte has been well characterized, exocytic vesicular traffic is less well understood. We show that the oocyte endoplasmic reticulum (ER) becomes concentrated into subcortical clusters during vitellogenesis. This ER reorganization requires Jagunal, which is an evolutionarily conserved ER membrane protein. Loss of Jagunal reduces vesicular traffic to the oocyte lateral membrane, but does not affect posterior polarized vesicular traffic, suggesting a role for Jagunal in facilitating vesicular traffic in the subcortex. Reduced membrane traffic caused by loss of Jagunal affects oocyte and bristle growth. We propose that ER reorganization is an important mechanism used by cells to prepare for an increased demand for membrane traffic, and Jagunal facilitates this process through ER clustering.

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.

scholarly journals Direct Binding of Cisplatin to p22phox, an Endoplasmic Reticulum (ER) Membrane Protein, Contributes to Cisplatin Resistance in Oral Squamous Cell Carcinoma (OSCC) Cells

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3815
Author(s):  
Chih-Chang Hung ◽  
Fu-An Li ◽  
Shih-Shin Liang ◽  
Ling-Feng Wang ◽  
I-Ling Lin ◽  
...  
Keyword(s):  
Squamous Cell Carcinoma ◽  
Endoplasmic Reticulum ◽  
Amino Acid ◽  
Oral Squamous Cell Carcinoma ◽  
Membrane Protein ◽  
Cell Carcinoma ◽  
Squamous Cell ◽  
Point Mutations ◽  
Prolonged Treatment ◽  
Er Membrane

Prolonged treatment with cisplatin (CDDP) frequently develops chemoresistance. We have previously shown that p22phox, an endoplasmic reticulum (ER) membrane protein, confers CDDP resistance by blocking CDDP nuclear entry in oral squamous cell carcinoma (OSCC) cells; however, the underlying mechanism remains unresolved. Using a fluorescent dye-labeled CDDP, here we show that CDDP can bind to p22phox in both cell-based and cell-free contexts. Subsequent detection of CDDP-peptide interaction by the Tris-Tricine-based electrophoresis revealed that GA-30, a synthetic peptide matching a region of the cytosolic domain of p22phox, could interact with CDDP. These results were further confirmed by liquid chromatography–mass spectrometry (LC–MS) analysis, from which MA-11, an 11-amino acid subdomain of the GA-30 domain, could largely account for the interaction. Amino acid substitutions at Cys50, Met65 and Met73, but not His72, significantly impaired the binding between CDDP and the GA-30 domain, thereby suggesting the potential CDDP-binding residues in p22phox protein. Consistently, the p22phox point mutations at Cys50, Met65 and Met73, but not His72, resensitized OSCC cells to CDDP-induced cytotoxicity and apoptosis. Finally, p22phox might have binding specificity for the platinum drugs, including CDDP, carboplatin and oxaliplatin. Together, we have not only identified p22phox as a novel CDDP-binding protein, but further highlighted the importance of such a drug-protein interaction in drug resistance.

scholarly journals Autophagosome formation in relation to the endoplasmic reticulum

2020 ◽  
Vol 27 (1) ◽  
Author(s):  
Yo-hei Yamamoto ◽  
Takeshi Noda
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Protein ◽  
De Novo ◽  
Transmembrane Protein ◽  
Lipid Transfer ◽  
Membrane Structures ◽  
Autophagosome Formation ◽  
Selective Autophagy ◽  
The Relationship ◽  
Er Membrane

Abstract Autophagy is a process in which a myriad membrane structures called autophagosomes are formed de novo in a single cell, which deliver the engulfed substrates into lysosomes for degradation. The size of the autophagosomes is relatively uniform in non-selective autophagy and variable in selective autophagy. It has been recently established that autophagosome formation occurs near the endoplasmic reticulum (ER). In this review, we have discussed recent advances in the relationship between autophagosome formation and endoplasmic reticulum. Autophagosome formation occurs near the ER subdomain enriched with phospholipid synthesizing enzymes like phosphatidylinositol synthase (PIS)/CDP-diacylglycerol-inositol 3-phosphatidyltransferase (CDIPT) and choline/ethanolamine phosphotransferase 1 (CEPT1). Autophagy-related protein 2 (Atg2), which is involved in autophagosome formation has a lipid transfer capacity and is proposed to directly transfer the lipid molecules from the ER to form autophagosomes. Vacuole membrane protein 1 (VMP1) and transmembrane protein 41b (TMEM41b) are ER membrane proteins that are associated with the formation of the subdomain. Recently, we have reported that an uncharacterized ER membrane protein possessing the DNAJ domain, called ERdj8/DNAJC16, is associated with the regulation of the size of autophagosomes. The localization of ERdj8/DNAJC16 partially overlaps with the PIS-enriched ER subdomain, thereby implying its association with autophagosome size determination.

scholarly journals Immunoisolaton of the Yeast Golgi Subcompartments and Characterization of a Novel Membrane Protein, Svp26, Discovered in the Sed5-Containing Compartments

2005 ◽  
Vol 25 (17) ◽  
pp. 7696-7710 ◽  
Author(s):  
Hironori Inadome ◽  
Yoichi Noda ◽  
Hiroyuki Adachi ◽  
Koji Yoda
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Golgi Apparatus ◽  
Membrane Protein ◽  
Considerable Portion ◽  
Marker Proteins ◽  
Evolutionarily Conserved ◽  
Golgi Compartment

ABSTRACT The Golgi apparatus consists of a set of vesicular compartments which are distinguished by their marker proteins. These compartments are physically separated in the Saccharomyces cerevisiae cell. To characterize them extensively, we immunoisolated vesicles carrying either of the SNAREs Sed5 or Tlg2, the markers of the early and late Golgi compartments, respectively, and analyzed the membrane proteins. The composition of proteins was mostly consistent with the position of each compartment in the traffic. We found six uncharacterized but evolutionarily conserved proteins and named them Svp26 (Sed5 compartment vesicle protein of 26 kDa), Tvp38, Tvp23, Tvp18, Tvp15 (Tlg2 compartment vesicle proteins of 38, 23, 18, and 15 kDa), and Gvp36 (Golgi vesicle protein of 36 kDa). The localization of Svp26 in the early Golgi compartment was confirmed by microscopic and biochemical means. Immunoprecipitation indicated that Svp26 binds to itself and a Golgi mannosyltransferase, Ktr3. In the absence of Svp26, a considerable portion of Ktr3 was mislocalized in the endoplasmic reticulum. Our data suggest that Svp26 has a novel role in retention of a subset of membrane proteins in the early Golgi compartments.

scholarly journals EMC1-dependent stabilization drives membrane penetration of a partially destabilized non-enveloped virus

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Parikshit Bagchi ◽  
Takamasa Inoue ◽  
Billy Tsai
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Protein ◽  
Membrane Transport ◽  
Molecular Chaperone ◽  
Viral Particle ◽  
The Novel ◽  
Membrane Penetration ◽  
Membrane Protein Complex ◽  
Enveloped Virus ◽  
Er Membrane

Destabilization of a non-enveloped virus generates a membrane transport-competent viral particle. Here we probe polyomavirus SV40 endoplasmic reticulum (ER)-to-cytosol membrane transport, a decisive infection step where destabilization initiates this non-enveloped virus for membrane penetration. We find that a member of the ER membrane protein complex (EMC) called EMC1 promotes SV40 ER membrane transport and infection. Surprisingly, EMC1 does so by using its predicted transmembrane residue D961 to bind to and stabilize the membrane-embedded partially destabilized SV40, thereby preventing premature viral disassembly. EMC1-dependent stabilization enables SV40 to engage a cytosolic extraction complex that ejects the virus into the cytosol. Thus EMC1 acts as a molecular chaperone, bracing the destabilized SV40 in a transport-competent state. Our findings reveal the novel principle that coordinated destabilization-stabilization drives membrane transport of a non-enveloped virus.

scholarly journals ORP5 localizes to ER–lipid droplet contacts and regulates the level of PI(4)P on lipid droplets

2019 ◽  
Vol 219 (1) ◽  
Author(s):  
Ximing Du ◽  
Linkang Zhou ◽  
Yvette Celine Aw ◽  
Hoi Yin Mak ◽  
Yanqing Xu ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Protein ◽  
Lipid Droplets ◽  
Lipid Synthesis ◽  
Integral Membrane Protein ◽  
Normal Cells ◽  
Bilayer Membranes ◽  
Contact Sites ◽  
Evolutionarily Conserved ◽  
Phosphatidylinositol 4

Lipid droplets (LDs) are evolutionarily conserved organelles that play important roles in cellular metabolism. Each LD is enclosed by a monolayer of phospholipids, distinct from bilayer membranes. During LD biogenesis and growth, this monolayer of lipids expands by acquiring phospholipids from the endoplasmic reticulum (ER) through nonvesicular mechanisms. Here, in a mini-screen, we find that ORP5, an integral membrane protein of the ER, can localize to ER–LD contact sites upon oleate loading. ORP5 interacts with LDs through its ligand-binding domain, and ORP5 deficiency enhances neutral lipid synthesis and increases the size of LDs. Importantly, there is significantly more phosphatidylinositol-4-phosphate (PI(4)P) and less phosphatidylserine (PS) on LDs in ORP5-deficient cells than in normal cells. The increased presence of PI(4)P on LDs in ORP5-deficient cells requires phosphatidylinositol 4-kinase 2-α. Our results thus demonstrate the existence of PI(4)P on LDs and suggest that LD-associated PI(4)P may be primarily used by ORP5 to deliver PS to LDs.

scholarly journals Stitching proteins into membranes, not sew simple

2014 ◽  
Vol 395 (12) ◽  
pp. 1417-1424 ◽  
Author(s):  
Paul Whitley ◽  
Ismael Mingarro
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Protein Assembly ◽  
Integral Membrane Proteins ◽  
Eukaryotic Cells ◽  
Endomembrane System ◽  
Correct Orientation ◽  
Tm Domain ◽  
Er Membrane

Abstract Most integral membrane proteins located within the endomembrane system of eukaryotic cells are first assembled co-translationally into the endoplasmic reticulum (ER) before being sorted and trafficked to other organelles. The assembly of membrane proteins is mediated by the ER translocon, which allows passage of lumenal domains through and lateral integration of transmembrane (TM) domains into the ER membrane. It may be convenient to imagine multi-TM domain containing membrane proteins being assembled by inserting their first TM domain in the correct orientation, with subsequent TM domains inserting with alternating orientations. However a simple threading model of assembly, with sequential insertion of one TM domain into the membrane after another, does not universally stand up to scrutiny. In this article we review some of the literature illustrating the complexities of membrane protein assembly. We also present our own thoughts on aspects that we feel are poorly understood. In short we hope to convince the readers that threading of membrane proteins into membranes is ‘not sew simple’ and a topic that requires further investigation.

scholarly journals Inheritance of cortical ER in yeast is required for normal septin organization

2007 ◽  
Vol 179 (3) ◽  
pp. 467-483 ◽  
Author(s):  
Christopher J.R. Loewen ◽  
Barry P. Young ◽  
Shabnam Tavassoli ◽  
Timothy P. Levine
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Membrane Protein ◽  
Budding Yeast ◽  
Polarized Growth ◽  
Bud Neck ◽  
Wee1 Kinase ◽  
Mother Cells ◽  
Er Membrane ◽  
In Cells

How cells monitor the distribution of organelles is largely unknown. In budding yeast, the largest subdomain of the endoplasmic reticulum (ER) is a network of cortical ER (cER) that adheres to the plasma membrane. Delivery of cER from mother cells to buds, which is termed cER inheritance, occurs as an orderly process early in budding. We find that cER inheritance is defective in cells lacking Scs2, a yeast homologue of the integral ER membrane protein VAP (vesicle-associated membrane protein–associated protein) conserved in all eukaryotes. Scs2 and human VAP both target yeast bud tips, suggesting a conserved action of VAP in attaching ER to sites of polarized growth. In addition, the loss of either Scs2 or Ice2 (another protein involved in cER inheritance) perturbs septin assembly at the bud neck. This perturbation leads to a delay in the transition through G2, activating the Saccharomyces wee1 kinase (Swe1) and the morphogenesis checkpoint. Thus, we identify a mechanism involved in sensing the distribution of ER.

scholarly journals Deficiencies in the Endoplasmic Reticulum (ER)-Membrane Protein Gab1p Perturb Transfer of Glycosylphosphatidylinositol to Proteins and Cause Perinuclear ER-associated Actin Bar Formation

2004 ◽  
Vol 15 (6) ◽  
pp. 2758-2770 ◽  
Author(s):  
Stephen J. Grimme ◽  
Xiang-Dong Gao ◽  
Paul S. Martin ◽  
Kim Tu ◽  
Serguei E. Tcheperegine ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Protein ◽  
Temperature Sensitive ◽  
Functional Interaction ◽  
Strong Suppression ◽  
A Subunit ◽  
Gpi Transamidase ◽  
Bar Formation ◽  
Er Membrane

The essential GAB1 gene, which encodes an endoplasmic reticulum (ER)-membrane protein, was identified in a screen for mutants defective in cellular morphogenesis. A temperature-sensitive gab1 mutant accumulates complete glycosylphosphatidylinositol (GPI) precursors, and its temperature sensitivity is suppressed differentially by overexpression of different subunits of the GPI transamidase, from strong suppression by Gpi8p and Gpi17p, to weak suppression by Gaa1p, and to no suppression by Gpi16p. In addition, both Gab1p and Gpi17p localize to the ER and are in the same protein complex in vivo. These findings suggest that Gab1p is a subunit of the GPI transamidase with distinct relationships to other subunits in the same complex. We also show that depletion of Gab1p or Gpi8p, but not Gpi17p, Gpi16p, or Gaa1p causes accumulation of cofilin-decorated actin bars that are closely associated with the perinuclear ER, which highlights a functional interaction between the ER network and the actin cytoskeleton.

Sign in / Sign up

Export Citation Format

Share Document