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The cell and tissues
Published in Peate Ian, Dutton Helen, Acute Nursing Care, 2020
The nucleus is a structure found in all human cells, except those identified earlier in the chapter. It is protected by a double nuclear envelope, the outer layer of which is continuous with the endoplasmic reticulum. The envelope has gaps in it, called pores, that allow the movement of specified molecules into and out of it. Protein molecules enter, and ribosomes and messenger ribonucleic acid (mRNA) exit. Signalling chemicals that can stimulate DNA transcription can also enter through these pores.
Manipulating the Intracellular Trafficking of Nucleic Acids
Published in Kenneth L. Brigham, Gene Therapy for Diseases of the Lung, 2020
Kathleen E. B Meyer, Lisa S. Uyechi, Francis C. Szoka
The inner and outer nuclear membranes, which would otherwise form a loose perinuclear compartment, are joined at nuclear pore complexes (NPCs) interspersed throughout the nuclear envelope (Fig. 4). These 125-MDa structures are composed of an estimated 100 proteins and span both membranes of the nuclear envelope (88,89). The NPC forms aqueous channels and supports both passive diffusion and active transport. It appears that the number of NPCs per nucleus (or NPCs/μm2 nuclear membrane) corresponds to the trafficking needs of the cell and varies with cell type, cell cycle, and metabolic activity; estimates of NPC density as low as < 1/μm2 for quiescent avian erythrocytes and up to 120/μm2 in tetrahymena (83). The structure and transport properties of NPCs are summarized in several recent reviews (83,88-95).
Molecular Organization of Entamoeba Histolytica
Published in Roberto R. Kretschmer, Amebiasis: Infection and Disease by Entamoeba histolytica, 2020
Isaura Meza, Haydee K. Torres-Guerrero, Marco A. Meraz
The nucleus in higher eukaryotes is a very complex and plastic element that changes its shape and organization during the cell cycle. Different structures are involved in this dynamic process. The nuclear envelope and the nuclear lamina disassemble and reassemble in a coordinated manner with a series of structural transformations of the chromosomes. During mitosis the chromosomes reach their most condensed state and are organized by the mitotic spindle for separation into the daughter cells. At the end of mitosis a cellular signal initiates reassembly of the interphase nucleus.
Exploiting active nuclear import for efficient delivery of Auger electron emitters into the cell nucleus
Published in International Journal of Radiation Biology, 2023
Andrey A. Rosenkranz, Tatiana A. Slastnikova, Mikhail O. Durymanov, Georgii P. Georgiev, Alexander S. Sobolev
For most of the cellular life, the contents of the cell nucleus are separated from the cytoplasm by the nuclear envelope, which consists of two phospholipidic membranes and intermembrane space that are permeated by numerous NPC (Lin and Hoelz 2019). NPCs are supramolecular protein structures that form rounded holes in the nuclear envelope where both nuclear membranes are fused. NPCs are embedded within these holes and form a stable protein scaffold. On the nuclear side, the scaffold forms eight extended fibers that are connected in a distal ring and form the nuclear basket. Another eight flexible fibers extend into the cytoplasm. Additional fiber-like extensions in a central opening generate the permeability barrier, which controls the import and export of macromolecules (Knockenhauer and Schwartz 2016). The main components of the eukaryotic NPC, called nucleoporins, are a family of approximately 30 proteins that form a part of the scaffolding and transport functions of NPC. The outer diameter, inner diameter of the central transport channel, height, and molecular mass of the human NPC is approximately 120 nm, 42.5 nm, 80 nm, and 110 MDa, respectively (Lin and Hoelz 2019).
Pseudo Pelger-Huët anomalies as potential biomarkers for acute exposure radiation dose in rhesus macaques (Macaca mulatta)
Published in International Journal of Radiation Biology, 2022
Joshua M. Hayes, John D. Olson, Yuiko Chino, J. Daniel Bourland, J. Mark Cline, Thomas E. Johnson
There is a distinction between the Pelger-Huët Anomaly (PHA) and the pseudo Pelger-Huët anomaly (PPHA); PHAs are naturally occurring while PPHAs are induced morphologies. PHAs were first described in 1928 by the German physician, Karl Pelger, and were believed to be a sign of poor prognosis for tuberculosis (Pelger 1928). However, in 1932 G.J Huët discovered PHAs were linked to an autosomal dominant mutation on the long arm of chromosome 1 (Huët 1931). The mutation was in a gene that encodes for the lamin-B receptor, which is a membrane-associated protein embedded in the inner nuclear membrane of the nuclear envelope. The lamin-B receptor has two functions that can be described by its location on the protein. The carboxyl terminus performs C14 sterol reductase activity which involves the breaking of carbon double bonds in cholesterol synthesis, while the amine terminus of the lamin-B receptor binds to an intermediate filament called lamin-B. Lamin-B in turn binds to the chromatin and provides structure to both the chromatin and the nucleoplasm (Holmer et al. 1998). The structure of the nucleus is incredibly important to granulocytes because a hyper-segmented nucleus makes it much easier for these cells to exit the blood vascular compartment via diapedesis. The structure of the nucleus also allows for ease in movement throughout tissues as the cell is migrating to areas undergoing the inflammation response (Colella and Hollensead 2012). An image of the lamin-B receptor with the sterol reductase carboxyl terminus and the chromatin tethering amino terminus can be seen in Figure 1.
Selinexor for the treatment of multiple myeloma
Published in Expert Opinion on Pharmacotherapy, 2020
Klaus Podar, Jatin Shah, Ajai Chari, Paul G Richardson, Sundar Jagannath
The nucleus is an organelle, which encapsulates the genetic material with a double membrane, the nuclear envelope, thereby separating transcription in the nucleus from the translational machinery in the cytoplasm. To allow adequate cell function this spatial compartmentalization in eukaryotic cells requires a finely tuned, selective and efficient bidirectional nuclear-cytoplasmic transport of specific proteins and mRNAs through the nuclear pore complex (NPC) of the nuclear envelope. The passage of macro-molecules (>40 kDa), cargo, through the NPC requires specific transport receptor proteins. The mammalian family of karyopherins, representing the main group of transport receptor proteins, consists of 20 members including karyopherin alpha (KPNA) 1–6, karyopherin beta (KPNB) 1, and exportin-1 (XPO-1), also termed chromosome region maintenance – 1 (CRM-1). Dependent on the presence of precise transport signs in cargo proteins, nuclear localization signals (NLS) or nuclear export signals (NES), karyopherins chaperone them into (importins) or out (exportins) of the nucleus using energy from the RanGTPase complex.