-
Tissue & Cell Feb 2008Electron microscopic examination of exocrine pancreatic tissues from the fish Scorpaena scrofa L., probably captured while replenishing the acinar cells, shows two main...
Electron microscopic examination of exocrine pancreatic tissues from the fish Scorpaena scrofa L., probably captured while replenishing the acinar cells, shows two main functional cell morphologies of the same cell type. One cell functional aspect contains numerous well-contrasted small vesicles, the zymogenic vesicles. The other functional morphology is mainly represented by a few cells containing large apical zymogen vesicles with many empty RER cisterns. In our observations, the zymogenic vesicles are always studded with ribosomes. The main cytological finding is to report that zymogenic vesicles can be extruded from the perinuclear space and it confirms the suspected, synthetic activity of this cell compartment. The pool of zymogenic vesicles, maintaining their coat of ribosomes, then fuses and transfers their content into the cis Golgi complex network. Finally, the zymogen vesicles are produced following the classical secretory pathway from the trans Golgi saccular network into the supranuclear, apical region of the acinar cells where the largest vesicles concentrate their content until secretion.
Topics: Animals; Cell Nucleus; Cytoplasm; Enzyme Precursors; Fishes; Golgi Apparatus; Pancreas, Exocrine
PubMed: 17961618
DOI: 10.1016/j.tice.2007.08.004 -
Virus Research Dec 2004Herpes virions are complex particles that consist of more than 30 different virally encoded proteins. The molecular basis of how this complicated structure is assembled... (Review)
Review
Herpes virions are complex particles that consist of more than 30 different virally encoded proteins. The molecular basis of how this complicated structure is assembled is only recently beginning to emerge. After replication in the host cell nucleus viral DNA is incorporated into preformed capsids, which leave the nucleus by a first budding event at the inner nuclear membrane resulting in the formation of primary enveloped virions in the perinuclear space. The primary envelope then fuses with the outer leaflet of the nuclear membrane thereby releasing nucleocapsids into the cytoplasm. Final envelopment, including the acquisition of more than 15 tegument and more than 10 envelope (glyco) proteins occurs by budding into Golgi-derived vesicles. Mature virions are released after fusion of the vesicle membrane with the plasma membrane of the cell. Thus, herpesvirus morphogenesis requires two different budding steps, which are distinct not only in the subcellular compartments in which they occur but also by the viral proteins involved. This review summarizes recent advances in our understanding of the two herpesvirus budding events.
Topics: Animals; Herpesviridae; Humans; Morphogenesis; Viral Envelope Proteins; Virion; Virus Assembly
PubMed: 15567495
DOI: 10.1016/j.virusres.2004.08.013 -
Experimental Cell Research Aug 1956
Topics: Electrons; Leukocytes; Microscopy; Microscopy, Electron
PubMed: 13375672
DOI: 10.1016/0014-4827(56)90126-4 -
Comptes Rendus Hebdomadaires Des... May 1956
Topics: Electrons; Leukocytes; Microscopy; Microscopy, Electron; Nuclear Envelope; Photography
PubMed: 13343557
DOI: No ID Found -
Journal of Experimental Botany Aug 2020The nuclear envelope delineates the eukaryotic cell nucleus. The membrane system of the nuclear envelope consists of an outer nuclear membrane and an inner nuclear... (Review)
Review
The nuclear envelope delineates the eukaryotic cell nucleus. The membrane system of the nuclear envelope consists of an outer nuclear membrane and an inner nuclear membrane separated by a perinuclear space. It serves as more than just a static barrier, since it regulates the communication between the nucleoplasm and the cytoplasm and provides the anchoring points where chromatin is attached. Fewer nuclear envelope proteins have been identified in plants in comparison with animals and yeasts. Here, we review the current state of knowledge of the nuclear envelope in plants, focusing on its role as a chromatin organizer and regulator of gene expression, as well as on the modifications that it undergoes to be efficiently disassembled and reassembled with each cell division. Advances in knowledge concerning the mitotic role of some nuclear envelope constituents are also presented. In addition, we summarize recent progress on the contribution of the nuclear envelope elements to telomere tethering and chromosome dynamics during the meiotic division in different plant species.
Topics: Animals; Cell Division; Chromatin; Cytoplasm; Nuclear Envelope; Telomere
PubMed: 32589712
DOI: 10.1093/jxb/eraa299 -
Redox Biology Jan 2021Mitochondria are strategically trafficked throughout the cell by the action of microtubule motors, the actin cytoskeleton and adapter proteins. The intracellular...
Mitochondria are strategically trafficked throughout the cell by the action of microtubule motors, the actin cytoskeleton and adapter proteins. The intracellular positioning of mitochondria supports subcellular levels of ATP, Ca and reactive oxygen species (ROS, i.e. hydrogen peroxide, HO). Previous work from our group showed that deletion of the mitochondrial adapter protein Miro1 leads to perinuclear clustering of mitochondria, leaving the cell periphery devoid of mitochondria which compromises peripheral energy status. Herein, we report that deletion of Miro1 significantly restricts subcellular HO levels to the perinuclear space which directly affects intracellular responses to elevated mitochondrial ROS. Using the genetically encoded HO-responsive fluorescent biosensor HyPer7, we show that the highest levels of subcellular HO map to sites of increased mitochondrial density. Deletion of Miro1 or disruption of microtubule dynamics with Taxol significantly reduces peripheral HO levels. Following inhibition of mitochondrial complex 1 with rotenone we observe elevated spikes of HO in the cell periphery and complementary oxidation of mitochondrial peroxiredoxin 3 (PRX3) and cytosolic peroxiredoxin 2 (PRX2). Conversely, in cells lacking Miro1, rotenone did not increase peripheral HO or PRX2 oxidation but rather lead to increased nuclear HO and an elevated DNA-damage response. Lastly, local levels of HyPer7 oxidation correlate with the size and abundance of focal adhesions (FAs) in MEFs and cells lacking Miro1 have significantly smaller focal adhesions and reduced phosphorylation levels of vinculin and p130Cas compared to Miro1 MEFs. Together, we present evidence that the intracellular distribution of mitochondria influences subcellular HO levels and local cellular responses dependent on mitochondrial ROS.
Topics: Hydrogen Peroxide; Mitochondria; Mitochondrial Proteins; Oxidation-Reduction; Reactive Oxygen Species
PubMed: 33341544
DOI: 10.1016/j.redox.2020.101818 -
Cell Calcium Mar 2020Numerous lines of evidence indicate that nuclear calcium concentration ([Ca]) may be controlled independently from cytosolic events by a local machinery. In particular,... (Review)
Review
Numerous lines of evidence indicate that nuclear calcium concentration ([Ca]) may be controlled independently from cytosolic events by a local machinery. In particular, the perinuclear space between the inner nuclear membrane (INM) and the outer nuclear membrane (ONM) of the nuclear envelope (NE) likely serves as an intracellular store for Ca ions. Since ONM is contiguous with the endoplasmic reticulum (ER), the perinuclear space is adjacent to the lumen of ER thus allowing a direct exchange of ions and factors between the two organelles. Moreover, INM and ONM are fused at the nuclear pore complex (NPC), which provides the only direct passageway between the nucleoplasm and cytoplasm. However, due to the presence of ion channels, exchangers and transporters, it has been generally accepted that nuclear ion fluxes may occur across ONM and INM. Within the INM, the Na/Ca exchanger (NCX) isoform 1 seems to play an important role in handling Ca through the different nuclear compartments. Particularly, nuclear NCX preferentially allows local Ca flowing from nucleoplasm into NE lumen thanks to the Na gradient created by the juxtaposed Na/K-ATPase. Such transfer reduces abnormal elevation of [Ca] within the nucleoplasm thus modulating specific transductional pathways and providing a protective mechanism against cell death. Despite very few studies on this issue, here we discuss those making major contribution to the field, also addressing the pathophysiological implication of nuclear NCX malfunction.
Topics: Animals; Calcium; Calcium Signaling; Cell Nucleus; Disease; Humans; Models, Biological; Sodium-Calcium Exchanger
PubMed: 31865040
DOI: 10.1016/j.ceca.2019.102143 -
Frontiers in Physiology 2018Since the discovery of the inner nuclear transmembrane protein emerin in the early 1990s, nuclear envelope (NE) components and related involvement in nuclei integrity... (Review)
Review
Since the discovery of the inner nuclear transmembrane protein emerin in the early 1990s, nuclear envelope (NE) components and related involvement in nuclei integrity and functionality have been highly investigated. The NE is composed of two distinct lipid bilayers described as the inner (INM) and outer (ONM) nuclear membrane. NE proteins can be specifically "integrated" in the INM (such as emerin and SUN proteins) or in the ONM such as nesprins. Additionally, flanked to the INM, the nuclear lamina, a proteinaceous meshwork mainly composed of lamins A and C completes NE composition. This network of proteins physically interplays to guarantee NE integrity and most importantly, shape the bridge between cytoplasmic cytoskeletons networks (such as microtubules and actin) and the genome, through the anchorage to the heterochromatin. The essential network driving the connection of nucleoskeleton with cytoskeleton takes place in the perinuclear space (the space between ONM and INM) with the contribution of the LINC complex (for Linker of Nucleoskeleton to Cytoskeleton), hosting KASH and SUN proteins interactions. This close interplay between compartments has been related to diverse functions from nuclear integrity, activity and positioning through mechanotransduction pathways. At the same time, mutations in NE components genes coding for proteins such as lamins or nesprins, had been associated with a wide range of congenital diseases including cardiac and muscular diseases. Although most of these NE associated proteins are ubiquitously expressed, a large number of tissue-specific disorders have been associated with diverse pathogenic mutations. Thus, diagnosis and molecular explanation of this group of diseases, commonly called "nuclear envelopathies," is currently challenging. This review aims, first, to give a better understanding of diverse functions of the LINC complex components, from the point of view of lamins and nesprins. Second, to summarize human congenital diseases with a special focus on muscle and heart abnormalities, caused by mutations in genes coding for these two types of NE associated proteins.
PubMed: 30245638
DOI: 10.3389/fphys.2018.01277 -
F1000Research 2017: Herpesvirus capsids are assembled in the nucleus, translocated to the perinuclear space by budding, acquiring tegument and envelope, or released to the cytoplasm via...
: 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. : 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. : The Golgi complex is a compact entity in a juxtanuclear position covered by a membrane on the face. 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. : 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.
PubMed: 30135710
DOI: 10.12688/f1000research.12252.2