Search results for " nucleus"

Cargo transport through the nuclear pore complex at a glance.

2021

ABSTRACT Bidirectional transport of macromolecules across the nuclear envelope is a hallmark of eukaryotic cells, in which the genetic material is compartmentalized inside the nucleus. The nuclear pore complex (NPC) is the major gateway to the nucleus and it regulates nucleocytoplasmic transport, which is key to processes including transcriptional regulation and cell cycle control. Accordingly, components of the nuclear transport machinery are often found to be dysregulated or hijacked in diseases. In this Cell Science at a Glance article and accompanying poster, we provide an overview of our current understanding of cargo transport through the NPC, from the basic transport signals and mach…

Survivin’s Dual Role: An Export’s View

2007

Survivin is proposed to function as a mitotic regulator and an apoptosis inhibitor during development and pathogenesis. As such, survivin has aroused keen interest in disparate areas of basic and translational research. Survivin acts as a subunit of the chromosomal passenger complex (CPC), composed of the mitotic kinase Aurora-B, Borealin and INCENP, and is essential for proper chromosome segregation and cytokinesis. Our recent findings indicate that the nuclear export receptor Crm1 is critically involved in tethering the CPC to the centromere by interacting with a leucine-rich nuclear export signal (NES), evolutionary conserved in all mammalian survivin proteins. In addition, the survivin/…

High nucleo-cytoplasmic concentration gradient of chloride in rat liver.

1966

PREVIOUSLY, a high nucleo-cytoplasmic concentration gradient of sodium was found in rat liver and other tissues1,2. Since the concentration of potassium also was higher in the nucleus than in the cytoplasm, about 500 µequiv./g dry weight of anions should exist in the nucleus if the assumption is correct that nucleic acids and basic proteins approximately neutralize each other. This communication presents data which demonstrate a high concentration of chloride in the nucleus of the rat-liver cell.

Nucleo-cytoplasmic shuttling of RNA-binding factors: mRNA buffering and beyond.

2022

Gene expression is a highly regulated process that adapts RNAs and proteins content to the cellular context. Under steady-state conditions, mRNA homeostasis is robustly maintained by tight controls that act on both nuclear transcription and cytoplasmic mRNA stability. In recent years, it has been revealed that several RNA-binding proteins (RBPs) that perform functions in mRNA decay can move to the nucleus and regulate transcription. The RBPs involved in transcription can also travel to the cytoplasm and regulate mRNA degradation and/or translation. The multifaceted functions of these shuttling nucleo-cytoplasm RBPs have raised the possibility that they can act as mRNA metabolism coordinator…

DNA-replication complex from cells infected with herpes virus.

2005

Herpes simplex virus (HSV) DNA synthesis is initiated in an intact cell system by a 36-residue ribonucleotide stretch [W.E.G. Müller, R.K. Zahn, J. Arendes, and D. Falke (1979) Virology, 98, 200-210]. In the present study a nucleoplasmic fraction was isolated from rabbit kidney cells infected with HSV (type 1), which catalyzes DNA synthesis. By means of specific assays, containing single-stranded deoxyribopolymers, it was elucidated that the replication complex contains both an RNA-synthesizing and a DNA-synthesizing enzyme. These enzymes were characterized as host cell RNA polymerase II and HSV-induced DNA polymerase. The RNA polymerase II synthesizes an RNA initiator with an average chain…

Binucleate cells in the Ehrlich ascites tumor. Action of 5-fluorouracil.

1987

Time-dependent frequency distribution of binucleate cells (BC) was studied in Ehrlich ascites tumor (EAT) growing in mice. In animals that received no further treatment, the number of BC increased slowly from 2.6% to 16.5% of total cells within 8 days. In animals that were treated with different doses of 5-fluorouracil (FU) we found clearly higher numbers of BC. The number of BC increased with tumor age. The increase observed after treatment was reached more quickly in animals that had received the highest FU dose. The final number of BC was also dependent on the age of the tumor at the time of FU injection.

Effects of the modulation of epoxide hydrolase activity on the binding of benzo[a]pyrene metabolites to DNA in the intact nuclei.

1983

Filopodia-like actin cables position nuclei in association with perinuclear actin in Drosophila nurse cells

2013

Summary Controlling the position of the nucleus is vital for a number of cellular processes from yeast to humans. In Drosophila nurse cells, nuclear positioning is crucial during dumping, when nurse cells contract and expel their contents into the oocyte. We provide evidence that in nurse cells, continuous filopodia-like actin cables, growing from the plasma membrane and extending to the nucleus, achieve nuclear positioning. These actin cables move nuclei away from ring canals. When nurse cells contract, actin cables associate laterally with the nuclei, in some cases inducing nuclear turning so that actin cables become partially wound around the nuclei. Our data suggest that a perinuclear a…

Induction of micronucleated and binucleate cells in Chinese hamster ovary (CHO) cells by cis-diamminedichloroplatinum (II): a morphological and morph…

1990

Abstract The mutagenicity and cytotoxicity of cis -diamminedichloroplatinum (II) (cisplatin) at doses of 5, 10 and 20 μg/ml in Chinese hamster ovary (CHO) cells have been examined. A morphological characterization of several cell types induced by cisplatin was carried out. The frequencies of both cells with micronuclei and binucleate cells as a time-dependent parameter have also been studied. Whilst the number of cells with micronuclei was found to decrease with time, the number of binucleate cells increased. The possible kinetic mechanism for the production of binucleate cells and cells with micronuclei is discussed. A morphometric analysis was also performed. The nuclear area in both trea…

Chromatin Domains and Regulation of Transcription

2007

Compartmentalization and compaction of DNA in the nucleus is the characteristic feature of eukaryotic cells. A fully extended DNA molecule has to be compacted 100,000 times to fit within the nucleus. At the same time it is critical that various DNA regions remain accessible for interaction with regulatory factors and transcription/replication factories. This puzzle is solved at the level of DNA packaging in chromatin that occurs in several steps: rolling of DNA onto nucleosomes, compaction of nucleosome fiber with formation of the so-called 30 nm fiber, and folding of the latter into the giant (50-200 kbp) loops, fixed onto the protein skeleton, the nuclear matrix. The general assumption is…