The relationship between the nuclear membranes and the endoplasmic reticulum in interphase cells

1980 ◽  
Vol 8 (4) ◽  
pp. 459-465 ◽  
Author(s):  
JONATHAN C. W. RICHARDSON ◽  
PAUL S. AGUTTER
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Membranes ◽  
Interphase Cells ◽  
The Relationship

The Role of Endoplasmic Reticulum in the Repair of Amoeba Nuclear Envelopes Damaged Microsurgically

1974 ◽  
Vol 14 (2) ◽  
pp. 421-437
Author(s):  
C. J. FLICKINGER
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Rough Endoplasmic Reticulum ◽  
Repair Process ◽  
Nuclear Membranes ◽  
Normal Configuration ◽  
Layer Characteristic ◽  
The Relationship ◽  
Coated Slide

The nuclear envelopes of amoebae were damaged microsurgically, and the fate of the lesions was studied with the electron microscope. Amoebae were placed on the surface of an agar-coated slide. Using a glass probe, the nucleus was pushed from an amoeba, damaged with a chopping motion of the probe, and reinserted into the amoeba. Cells were prepared for electron microscopy at intervals of between 10 min and 4 days after the manipulation. Nuclear envelopes studied between 10 min and 1 h after the injury displayed extensive damage, including numerous holes in the nuclear membranes. Beginning 15 min after the manipulation, pieces of rough endoplasmic reticulum intruded into the holes in the nuclear membranes. These pieces of rough endoplasmic reticulum subsequently appeared to become connected to the nuclear membranes at the margins of the holes. By 1 day following the injury, many cells had died, but the nuclear membranes were intact in those cells that survived. The elaborate fibrous lamina or honeycomb layer characteristic of the amoeba nuclear envelope was resistant to early changes after the manipulation. Patches of disorganization of the fibrous lamina were present 5 h to 1 day after injury, but the altered parts showed evidence of progress toward a return to normal configuration by 4 days after the injury. It is proposed that the rough endoplasmic reticulum participates in the repair of injury to the nuclear membranes. The similarity of this repair process to reconstitution of the nuclear envelope in telophase of mitosis is noted, and the relationship between the nuclear envelope and the rough endoplasmic reticulum is discussed.

scholarly journals Single, context-specific glycans can target misfolded glycoproteins for ER-associated degradation

2005 ◽  
Vol 169 (1) ◽  
pp. 73-82 ◽  
Author(s):  
Eric D. Spear ◽  
Davis T.W. Ng
Keyword(s):  
Quality Control ◽  
Endoplasmic Reticulum ◽  
Secretory Protein ◽  
Carboxypeptidase Y ◽  
Er Quality Control ◽  
Systematic Analysis ◽  
Proteinase A ◽  
Context Specific ◽  
The Relationship ◽  
Erad Pathway

The endoplasmic reticulum (ER) maintains an environment essential for secretory protein folding. Consequently, the premature transport of polypeptides would be harmful to the cell. To avert this scenario, mechanisms collectively termed “ER quality control” prevent the transport of nascent polypeptides until they properly fold. Irreversibly misfolded molecules are sorted for disposal by the ER-associated degradation (ERAD) pathway. To better understand the relationship between quality control and ERAD, we studied a new misfolded variant of carboxypeptidase Y (CPY). The molecule was recognized and retained by ER quality control but failed to enter the ERAD pathway. Systematic analysis revealed that a single, specific N-linked glycan of CPY was required for sorting into the pathway. The determinant is dependent on the putative lectin-like receptor Htm1/Mnl1p. The discovery of a similar signal in misfolded proteinase A supported the generality of the mechanism. These studies show that specific signals embedded in glycoproteins can direct their degradation if they fail to fold.

Apigetrin Promotes Cell Autophagy by Activating the Endoplasmic Reticulum Stress in Human Cervical Cancer Hela Cells

2021 ◽  
Vol 20 (1) ◽  
pp. 56-63
Author(s):  
Li Jiang ◽  
Zhi-Cheng Yao ◽  
Miao-Miao Liu ◽  
Run-Hui Ma ◽  
Kiran Thakur
Keyword(s):  
Cervical Cancer ◽  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Hela Cells ◽  
Fruits And Vegetables ◽  
Radical Scavenging ◽  
Anticancer Activities ◽  
Treatment Results ◽  
Metastasis Rate ◽  
The Relationship

Cervical cancer has always been the top malignant cancer among female cancers in the world. Due to its recurrence, metastasis rate, and drug resistance, the treatment results of cervical cancer have been unsatisfactory. Apigetrin is present in a variety of fruits and vegetables and has been reported to have antioxidant, free radical scavenging, anti-inflammatory, and anticancer activities. Therefore, this study focuses on the effect of apigetrin on the autophagy of cervical cancer HeLa cells based on the previous research. The results showed that apigetrin can enhance the autophagy fluorescence of light chain 3B (LC3B), and further combined with quantitative real-time PCR (qPCR) and Western blotting found that the expression of autophagy-related genes and proteins p-mTOR, Beclin1, and LC3B increased, while the expression of AMPK, ULK1, and p62 decreased. In addition, apigetrin also promoted the release of Ca2+, the PERK/eIF2α/ATF4/chop, and IRE1α pathways activate endoplasmic reticulum (ER) stress. The addition of 4PBA proved that ER stress promoted autophagy in HeLa cells. Finally, the addition of the 3-MA indicates the relationship between autophagy and apoptosis in HeLa cells. Our results indicate that apigetrin has a certain anticancer potential and can be used as a drug adjuvant and food additive for the prevention and treatment of cervical cancer.

Interaction of the smooth endoplasmic reticulum and mitochondria

2006 ◽  
Vol 34 (3) ◽  
pp. 370-373 ◽  
Author(s):  
J.G. Goetz ◽  
I.R. Nabi
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Close Association ◽  
Cytosolic Calcium ◽  
Functional Roles ◽  
Calcium Dependent ◽  
Motility Factor ◽  
Calcium Sequestration ◽  
Multiple Domains ◽  
The Relationship

The ER (endoplasmic reticulum) is composed of multiple domains including the nuclear envelope, ribosome-studded rough ER and the SER (smooth ER). The SER can also be functionally segregated into domains that regulate ER–Golgi traffic (transitional ER), ERAD (ER-associated degradation), sterol and lipid biosynthesis and calcium sequestration. The last two, as well as apoptosis, are critically regulated by the close association of the SER with mitochondria. Studies with AMFR (autocrine motility factor receptor) have defined an SER domain whose integrity and mitochondrial association can be modulated by ilimaquinone as well as by free cytosolic calcium levels in the normal physiological range. AMFR is an E3 ubiquitin ligase that targets its ligand directly to the SER via a caveolae/raft-dependent pathway. In the present review, we will address the relationship between the calcium-dependent morphology and mitochondrial association of the SER and its various functional roles in the cell.

scholarly journals Endoplasmic reticulum-to-Golgi transitions upon herpes virus infection

F1000Research ◽  
2018 ◽  
Vol 6 ◽  
pp. 1804 ◽  
Author(s):  
Peter Wild ◽  
Andres Kaech ◽  
Elisabeth M. Schraner ◽  
Ladina Walser ◽  
Mathias Ackermann
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Golgi Complex ◽  
Nuclear Membrane ◽  
Progeny Virus ◽  
Cytoplasmic Matrix ◽  
Outer Nuclear Membrane ◽  
Nuclear Membranes ◽  
Perinuclear Space ◽  
Hsv 1

Background: Herpesvirus capsids are assembled in the nucleus, translocated to the perinuclear space by budding, acquiring tegument and envelope, or released to the cytoplasm via impaired nuclear envelope. One model proposes that envelopment, “de-envelopment” and “re-envelopment” is essential for production of infectious virus. Glycoproteins gB/gH were reported to be essential for de-envelopment, by fusion of the “primary” envelope with the outer nuclear membrane. Yet, a high proportion of enveloped virions generated from genomes with deleted gB/gH were found in the cytoplasm and extracellular space, suggesting the existence of alternative exit routes.Methods: We investigated the relatedness between the nuclear envelope and membranes of the endoplasmic reticulum and Golgi complex, in cells infected with either herpes simplex virus 1 (HSV-1) or a Us3 deletion mutant thereof, or with bovine herpesvirus 1 (BoHV-1) by transmission and scanning electron microscopy, employing freezing technique protocols.Results:  The Golgi complex is a compact entity in a juxtanuclear position covered by a membrane on thecisface. Golgi membranes merge with membranes of the endoplasmic reticulum forming an entity with the perinuclear space. All compartments contained enveloped virions. After treatment with brefeldin A, HSV-1 virions aggregated in the perinuclear space and endoplasmic reticulum, while infectious progeny virus was still produced.Conclusions: The data suggest that virions derived by budding at nuclear membranes are intraluminally transported from the perinuclear space via Golgi -endoplasmic reticulum transitions into Golgi cisternae for packaging. Virions derived by budding at nuclear membranes are infective like Us3 deletion mutants, which  accumulate in the perinuclear space. Therefore, i) de-envelopment followed by re-envelopment is not essential for production of infective progeny virus, ii) the process taking place at the outer nuclear membrane is budding not fusion, and iii) naked capsids gain access to the cytoplasmic matrix via impaired nuclear envelope as reported earlier.

The polypeptides of rat liver nuclear envelope. II. Comparison of rat liver nuclear membrane polypeptides with those of the rough endoplasmic reticulum

1980 ◽  
Vol 43 (1) ◽  
pp. 269-277
Author(s):  
J.C. Richardson ◽  
A.H. Maddy
Keyword(s):  
Endoplasmic Reticulum ◽  
Rat Liver ◽  
Rough Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Relative Proportion ◽  
Membrane System ◽  
Membrane Systems ◽  
Nuclear Membranes ◽  
Cytoplasmic Surface ◽  
Triton X

Nuclear envelopes are separated into pore-lamina and membrane sub-fractions by extraction in 2.0% Triton X-100 followed by pelleting of the pore-laminae. The polypeptides of these subfractions are then compared with those from isolated rough endoplasmic reticulum. The dispositions of individual polypeptides in the cytoplasmic surface of nuclear envelopes and rought endoplasmic reticulum were studied by lactoperoxidase-catalysed iodination. These studies show that although the nuclear membranes exhibit several homologies with the Triton-soluble polypeptides of the rough endoplasmic reticulum the relative proportion of individual polypeptides within the two systems are very largely different. The cytoplasmic surfaces of the 2 membrane systems show only 2 obvious homologies at 105 000 and 15 000 mol. wt and the overall impression is that, at least in rat liver, the outer nuclear membrane is very substantially differentiated from rough endoplasmic reticulum. It is concluded that the nuclear membranes may not be regarded as a mere continuum of the endoplasmic reticulum, but should be seen as a highly specialized membrane system in their own right.

scholarly journals Chemotherapy Resistance Explained through Endoplasmic Reticulum Stress-Dependent Signaling

Cancers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 338 ◽  
Author(s):  
Entaz Bahar ◽  
Ji-Ye Kim ◽  
Hyonok Yoon
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Molecular Mechanism ◽  
Molecular Mechanisms ◽  
Cellular Proliferation ◽  
Protein Quality ◽  
Chemotherapy Resistance ◽  
Persistent Problem ◽  
Stress Dependent ◽  
The Relationship

Cancers cells have the ability to develop chemotherapy resistance, which is a persistent problem during cancer treatment. Chemotherapy resistance develops through different molecular mechanisms, which lead to modification of the cancer cells signals needed for cellular proliferation or for stimulating an immune response. The endoplasmic reticulum (ER) is an important organelle involved in protein quality control, by promoting the correct folding of protein and ER-mediated degradation of unfolded or misfolded protein, namely, ER-associated degradation. Disturbances of the normal ER functions causes an accumulation of unfolded or misfolded proteins in the ER lumen, resulting in a condition called “ER stress (ERS).” ERS triggers the unfolded protein response (UPR)—also called the ERS response (ERSR)—to restore homeostasis or activate cell death. Although the ERSR is one emerging potential target for chemotherapeutics to treat cancer, it is also critical for chemotherapeutics resistance, as well. However, the detailed molecular mechanism of the relationship between the ERSR and tumor survival or drug resistance remains to be fully understood. In this review, we aim to describe the most vital molecular mechanism of the relationship between the ERSR and chemotherapy resistance. Moreover, the review also discusses the molecular mechanism of ER stress-mediated apoptosis on cancer treatments.

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 Endoplasmic Reticulum Stress and Unfolded Protein Response in Breast Cancer: The Balance between Apoptosis and Autophagy and Its Role in Drug Resistance

2019 ◽  
Vol 20 (4) ◽  
pp. 857 ◽  
Author(s):  
Lorenza Sisinni ◽  
Michele Pietrafesa ◽  
Silvia Lepore ◽  
Francesca Maddalena ◽  
Valentina Condelli ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Unfolded Protein Response ◽  
Inflammatory Diseases ◽  
Unfolded Protein ◽  
Chronic Activation ◽  
The Unfolded Protein Response ◽  
Protein Response ◽  
The Relationship

The unfolded protein response (UPR) is a stress response activated by the accumulation of unfolded or misfolded proteins in the lumen of the endoplasmic reticulum (ER) and its uncontrolled activation is mechanistically responsible for several human pathologies, including metabolic, neurodegenerative, and inflammatory diseases, and cancer. Indeed, ER stress and the downstream UPR activation lead to changes in the levels and activities of key regulators of cell survival and autophagy and this is physiologically finalized to restore metabolic homeostasis with the integration of pro-death or/and pro-survival signals. By contrast, the chronic activation of UPR in cancer cells is widely considered a mechanism of tumor progression. In this review, we focus on the relationship between ER stress, apoptosis, and autophagy in human breast cancer and the interplay between the activation of UPR and resistance to anticancer therapies with the aim to disclose novel therapeutic scenarios. The hypothesis that autophagy and UPR may provide novel molecular targets in human malignancies is discussed.

scholarly journals THE NUCLEAR ENVELOPE

1955 ◽  
Vol 1 (3) ◽  
pp. 257-270 ◽  
Author(s):  
Michael L. Watson
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Particulate Material ◽  
Tangential Section ◽  
Resting Cells ◽  
Thin Sections ◽  
Outer Membranes ◽  
Perinuclear Space ◽  
Interphase Cells ◽  
Embryonic Ectoderm

An electron microscope study of thin sections of interphase cells has revealed the following:— Circular pores are formed in the double nuclear envelope by continuities between the inner and outer membranes which permit contact between the nucleoplasm and the cytoplasm unmediated by a well defined membrane. The pores, seen in sections normal to the nuclear envelope, are profiles of the ring-shaped structures described by others and seen in tangential section. The inner and outer nuclear membranes are continuous with one another and enclose the perinuclear space. The pores contain a diffuse, faintly particulate material. A survey of cells of the rat derived from the embryonic ectoderm, mesoderm, and endoderm, and of a protozoan and an alga has revealed pores in all tissues examined, without exception. It is concluded that pores in the nuclear envelope are a fundamental feature of all resting cells. In certain cells, the outer nuclear membrane is continuous with membranes of the endoplasmic reticulum, hence the perinuclear space is continuous with cavities enclosed by those membranes. There are indications that this is true for all resting cells, at least in a transitory way. On the basis of these observations, the hypothesis is made that two pathways of exchange exist between the nucleus and the cytoplasm; by way of the perinuclear space and cavities of the endoplasmic reticulum and by way of the pores in the nuclear envelope.

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