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Cellular Microbiology Aug 2021Annulate lamellae (AL) have been observed many times over the years on electron micrographs of rapidly dividing cells, but little is known about these unusual organelles... (Review)
Review
Annulate lamellae (AL) have been observed many times over the years on electron micrographs of rapidly dividing cells, but little is known about these unusual organelles consisting of stacked sheets of endoplasmic reticulum-derived membranes with nuclear pore complexes (NPCs). Evidence is growing for a role of AL in viral infection. AL have been observed early in the life cycles of the hepatitis C virus (HCV) and, more recently, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), suggesting a specific induction of mechanisms potentially useful to these pathogens. Like other positive-strand RNA viruses, these viruses induce host cells membranes rearrangements. The NPCs of AL could potentially mediate exchanges between these partially sealed compartments and the cytoplasm. AL may also be involved in regulating Ca homeostasis or cell cycle control. They were recently observed in cells infected with Theileria annulata, an intracellular protozoan parasite inducing cell proliferation. Further studies are required to clarify their role in intracellular pathogen/host-cell interactions.
Topics: Animals; COVID-19; Cytoplasm; Endoplasmic Reticulum; Host-Pathogen Interactions; Humans; Organelles; SARS-CoV-2
PubMed: 33740320
DOI: 10.1111/cmi.13328 -
Ageing Research Reviews Jun 2023Mitochondria-associated endoplasmic reticulum membranes (MAMs) are dynamic coupling structures between mitochondria and the endoplasmic reticulum (ER). As a new... (Review)
Review
Mitochondria-associated endoplasmic reticulum membranes (MAMs) are dynamic coupling structures between mitochondria and the endoplasmic reticulum (ER). As a new subcellular structure, MAMs combine the two critical organelle functions. Mitochondria and the ER could regulate each other via MAMs. MAMs are involved in calcium (Ca) homeostasis, autophagy, ER stress, lipid metabolism, etc. Researchers have found that MAMs are closely related to metabolic syndrome and neurodegenerative diseases (NDs). The formation of MAMs and their functions depend on specific proteins. Numerous protein enrichments, such as the IP3R-Grp75-VDAC complex, constitute MAMs. The changes in these proteins govern the interaction between mitochondria and the ER; they also affect the biological functions of MAMs. S-palmitoylation is a reversible protein post-translational modification (PTM) that mainly occurs on protein cysteine residues. More and more studies have shown that the S-palmitoylation of proteins is closely related to their membrane localization. Here, we first briefly describe the composition and function of MAMs, reviewing the component and biological roles of MAMs mediated by S-palmitoylation, elaborating on S-palmitoylated proteins in Ca flux, lipid rafts, and so on. We try to provide new insight into the molecular basis of MAMs-related diseases, mainly NDs. Finally, we propose potential drug compounds targeting S-palmitoylation.
Topics: Humans; Mitochondrial Membranes; Protein S; Lipoylation; Neurodegenerative Diseases; Mitochondria; Endoplasmic Reticulum; Endoplasmic Reticulum Stress
PubMed: 37004843
DOI: 10.1016/j.arr.2023.101920 -
Sheng Wu Gong Cheng Xue Bao = Chinese... Jan 2021Endoplasmic reticulum (ER) is an important organelle where folding and post-translational modification of secretory and transmembrane proteins take place. During virus...
Endoplasmic reticulum (ER) is an important organelle where folding and post-translational modification of secretory and transmembrane proteins take place. During virus infection, cellular or viral unfolded and misfolded proteins accumulate in the ER in an event called ER stress. To maintain the equilibrium homeostasis of the ER, signal-transduction pathways, known as unfolded protein response (UPR), are activated. The viruses in turn manipulate UPR to maintain an environment favorable for virus survival and replication. Herpesviruses are enveloped DNA viruses that produce over 70 viral proteins. Modification and maturation of large quantities of viral glycosylated envelope proteins during virus replication may induce ER stress, while ER stress play both positive and negative roles in virus infection. Here we summarize the research progress of crosstalk between herpesvirus infection and the virus-induced ER stress.
Topics: Endoplasmic Reticulum; Endoplasmic Reticulum Stress; Herpesviridae; Signal Transduction; Unfolded Protein Response
PubMed: 33501790
DOI: 10.13345/j.cjb.200226 -
Molecular and Cellular Neurosciences Jun 2023The endoplasmic reticulum (ER) is the largest membrane compartment within eukaryotic cells and is emerging as a key coordinator of many cellular processes. The ER can... (Review)
Review
The endoplasmic reticulum (ER) is the largest membrane compartment within eukaryotic cells and is emerging as a key coordinator of many cellular processes. The ER can modulate local calcium fluxes and communicate with other organelles like the plasma membrane. The importance of ER in neuronal processes such as neurite growth, axon repair and neurotransmission has recently gained much attention. In this review, we highlight the importance of the ER tubular network in axonal homeostasis and discuss how the generation and maintenance of the thin tubular ER network in axons and synapses, requires a cooperative effort of ER-shaping proteins, cytoskeleton and autophagy processes.
Topics: Neurons; Axons; Neurites; Microtubules; Endoplasmic Reticulum; Autophagy; Endoplasmic Reticulum Stress
PubMed: 36781033
DOI: 10.1016/j.mcn.2023.103822 -
Intertwined and Finely Balanced: Endoplasmic Reticulum Morphology, Dynamics, Function, and Diseases.Cells Sep 2021The endoplasmic reticulum (ER) is an organelle that is responsible for many essential subcellular processes. Interconnected narrow tubules at the periphery and thicker... (Review)
Review
The endoplasmic reticulum (ER) is an organelle that is responsible for many essential subcellular processes. Interconnected narrow tubules at the periphery and thicker sheet-like regions in the perinuclear region are linked to the nuclear envelope. It is becoming apparent that the complex morphology and dynamics of the ER are linked to its function. Mutations in the proteins involved in regulating ER structure and movement are implicated in many diseases including neurodegenerative diseases such as Alzheimer's, Parkinson's, and amyotrophic lateral sclerosis (ALS). The ER is also hijacked by pathogens to promote their replication. Bacteria such as and as well as the Zika virus, bind to ER morphology and dynamics-regulating proteins to exploit the functions of the ER to their advantage. This review covers our understanding of ER morphology, including the functional subdomains and membrane contact sites that the organelle forms. We also focus on ER dynamics and the current efforts to quantify ER motion and discuss the diseases related to ER morphology and dynamics.
Topics: Animals; Cytoskeleton; Endoplasmic Reticulum; Humans; Lipids; Membrane Proteins; Microtubules; Mitochondria; Mitochondrial Membranes; Nuclear Envelope; Structure-Activity Relationship
PubMed: 34571990
DOI: 10.3390/cells10092341 -
Cold Spring Harbor Perspectives in... Jun 2023The endoplasmic reticulum (ER) is a continuous, highly dynamic membrane compartment that is crucial for numerous basic cellular functions. The ER stretches from the... (Review)
Review
The endoplasmic reticulum (ER) is a continuous, highly dynamic membrane compartment that is crucial for numerous basic cellular functions. The ER stretches from the nuclear envelope to the outer periphery of all living eukaryotic cells. This ubiquitous organelle shows remarkable structural complexity, adopting a range of shapes, curvatures, and length scales. Canonically, the ER is thought to be composed of two simple membrane elements: sheets and tubules. However, recent advances in superresolution light microscopy and three-dimensional electron microscopy have revealed an astounding diversity of nanoscale ER structures, greatly expanding our view of ER organization. In this review, we describe these diverse ER structures, focusing on what is known of their regulation and associated functions in mammalian cells.
Topics: Animals; Endoplasmic Reticulum; Nuclear Envelope; Microscopy, Electron; Mammals
PubMed: 36123032
DOI: 10.1101/cshperspect.a041259 -
Annual Review of Analytical Chemistry... Jun 2022Cellular organelles are highly specialized compartments with distinct functions. With the increasing resolution of detection methods, it is becoming clearer that same... (Review)
Review
Cellular organelles are highly specialized compartments with distinct functions. With the increasing resolution of detection methods, it is becoming clearer that same organelles may have different functions or properties not only within different cell populations of a tissue but also within the same cell. Dysfunction or altered function affects the organelle itself and may also lead to malignancies or undesirable cell death. To understand cellular function or dysfunction, it is therefore necessary to analyze cellular components at the single-organelle level. Here, we review the recent advances in analyzing cellular function at single-organelle resolution using high-parameter flow cytometry or multicolor confocal microscopy. We focus on the analysis of mitochondria, as they are organelles at the crossroads of various cellular signaling pathways and functions. However, most of the applied methods/technologies are transferable to any other organelle, such as the endoplasmic reticulum, lysosomes, or peroxisomes.
Topics: Endoplasmic Reticulum; Lysosomes; Microscopy, Confocal; Mitochondria; Peroxisomes
PubMed: 35303775
DOI: 10.1146/annurev-anchem-061020-111722 -
Methods in Cell Biology 2021
Topics: Endoplasmic Reticulum; Golgi Apparatus; Intracellular Membranes; Protein Transport
PubMed: 34311874
DOI: 10.1016/S0091-679X(21)00081-9 -
Cells Sep 2019Efficiency and fidelity of protein secretion are achieved thanks to the presence of different steps, located sequentially in time and space along the secretory... (Review)
Review
Efficiency and fidelity of protein secretion are achieved thanks to the presence of different steps, located sequentially in time and space along the secretory compartment, controlling protein folding and maturation. After entering into the endoplasmic reticulum (ER), secretory proteins attain their native structure thanks to specific chaperones and enzymes. Only correctly folded molecules are allowed by quality control (QC) mechanisms to leave the ER and proceed to downstream compartments. Proteins that cannot fold properly are instead retained in the ER to be finally destined to proteasomal degradation. Exiting from the ER requires, in most cases, the use of coated vesicles, departing at the ER exit sites, which will fuse with the Golgi compartment, thus releasing their cargoes. Protein accumulation in the ER can be caused by a too stringent QC or by ineffective transport: these situations could be deleterious for the organism, due to the loss of the secreted protein, and to the cell itself, because of abnormal increase of protein concentration in the ER. In both cases, diseases can arise. In this review, we will describe the pathophysiology of protein folding and transport between the ER and the Golgi compartment.
Topics: Biological Transport; COP-Coated Vesicles; Endoplasmic Reticulum; Golgi Apparatus; Protein Folding; Protein Transport; Proteins
PubMed: 31500301
DOI: 10.3390/cells8091051 -
BioEssays : News and Reviews in... Feb 2021Autophagy functions in both selective and non-selective ways to maintain cellular homeostasis. Endoplasmic reticulum autophagy (ER-phagy) is a subclass of autophagy...
Autophagy functions in both selective and non-selective ways to maintain cellular homeostasis. Endoplasmic reticulum autophagy (ER-phagy) is a subclass of autophagy responsible for the degradation of the endoplasmic reticulum through selective encapsulation into autophagosomes. ER-phagy occurs both under physiological conditions and in response to stress cues, and plays a crucial role in maintaining the homeostatic control of the organelle. Although specific receptors that target parts of the ER membrane, as well as, internal proteins for lysosomal degradation have been identified, the molecular regulation of ER-phagy has been elusive. Recent work has uncovered novel regulators of ER-phagy that involve post-translational modifications of ER-resident proteins and functional cross-talk with other cellular processes. Herein, we discuss how morphology affects the function of the peripheral ER, and how ER-phagy modulates the turnover of this organelle. We also address how ER-phagy is regulated at the molecular level, considering implications relevant to human diseases.
Topics: Autophagy; Endoplasmic Reticulum; Endoplasmic Reticulum Stress; Humans; Membrane Proteins; Protein Processing, Post-Translational
PubMed: 33210303
DOI: 10.1002/bies.202000212