scholarly journals The yeast RNA1 gene product necessary for RNA processing is located in the cytosol and apparently excluded from the nucleus.

1990 ◽  
Vol 111 (2) ◽  
pp. 309-321 ◽  
Author(s):  
A K Hopper ◽  
H M Traglia ◽  
R W Dunst
Keyword(s):  
Gene Product ◽  
Indirect Immunofluorescence ◽  
Rna Processing ◽  
Nuclear Transport ◽  
Stress Conditions ◽  
Nuclear Proteins ◽  
Intracellular Location ◽  
Trna Splicing ◽  
Immunofluorescence Localization ◽  
Endogenous Protein

The yeast RNA1 gene is required for RNA processing and nuclear transport of RNA. The rna1-1 mutation of this locus causes defects in pre-tRNA splicing, processing of the primary pre-rRNA transcript, production of mRNA and export of RNA from the nucleus to the cytosol. To understand how this gene product can pleiotropically affect these processes, we sought to determine the intracellular location of the RNA1 protein. As determined by indirect immunofluorescence localization and organelle fractionation, the RNA1 antigen is found exclusively or primarily in the cytoplasm. Only a tiny fraction of the endogenous protein could be localized to and functional in the nucleus. Furthermore, the RNA1 antigen does not localize differently under stress conditions. These findings suggest that the RNA1 protein is not directly involved in RNA processing but may modify nuclear proteins or otherwise transmit a signal from the cytosol to the nucleus or play a role in maintaining the integrity of the nucleus.

Mechanisms of Nuclear Transport in the cell: RNA exosome in Saccharomyces cerevisiae

Bionatura ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 1423-1426
Author(s):  
Bruna Rech ◽  
Fernando A. Gonzales-Zubiate
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Catalytic Activity ◽  
Rna Processing ◽  
Cellular Localization ◽  
Nuclear Transport ◽  
Single Units ◽  
Yeast Saccharomyces Cerevisiae ◽  
Rna Transcripts ◽  
Non Coding Rnas ◽  
Rna Exosome

Ribonucleases (RNases) functions in the cell include precise maturation of non- coding RNAs and degradation of specific RNA transcripts that are no longer necessary. RNAses are present in the cell as single units or assembled as multimeric complexes; one of these complexes is the RNA exosome, a highly conserved complex essential for RNA processing and degradation. In the yeast Saccharomyces cerevisiae, the RNA exosome comprises eleven subunits, two with catalytic activity: Rrp6 and Rrp44, where the Rrp6 subunit is exclusively nuclear. Despite the RNA exosome has been intensively investigated since its discovery in 1997, only a few studies were accomplished concerning its nuclear transport. This review describes recent research about cellular localization and transport of this essential complex.

SRN1, a yeast gene involved in RNA processing, is identical to HEX2/REG1, a negative regulator in glucose repression

1992 ◽  
Vol 12 (6) ◽  
pp. 2673-2680
Author(s):  
K S Tung ◽  
L L Norbeck ◽  
S L Nolan ◽  
N S Atkinson ◽  
A K Hopper
Keyword(s):  
Rna Processing ◽  
Carbon Catabolite Repression ◽  
Glucose Repression ◽  
Complementation Group ◽  
Negative Regulator ◽  
Rrna Processing ◽  
Yeast Gene ◽  
Trna Splicing ◽  
Intervening Sequences ◽  
First Time

The yeast RNA1 gene encodes a cytosolic protein that affects pre-tRNA splicing, pre-rRNA processing, the production of mRNA, and the export of RNA from the nucleus to the cytosol. In an attempt to understand how the RNA1 protein affects such a diverse set of processes, we sought second-site suppressors of a mutation, rna1-1, of the RNA1 locus. Mutations in a single complementation group were obtained. These lesions proved to be in the same gene, SRN1, identified previously in a search for second-site suppressors of mutations that affect the removal of intervening sequences from pre-mRNAs. The SRN1 gene was mapped, cloned, and sequenced. DNA sequence analysis and the phenotype of disruption mutations showed that, surprisingly, SRN1 is identical to HEX2/REG1, a gene that negatively regulates glucose-repressible genes. Interestingly, SRN1 is not a negative regulator of RNA1 at the transcriptional, translational, or protein stability level. However, SRN1 does regulate the level of two newly discovered antigens, p43 and p70, one of which is not glucose repressible. These studies for the first time link RNA processing and carbon catabolite repression.

scholarly journals The Mitochondrial Lon Protease: Novel Functions off the Beaten Track?

Biomolecules ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 253 ◽  
Author(s):  
Wolfgang Voos ◽  
Karen Pollecker
Keyword(s):  
Mammalian Cells ◽  
Protein Quality ◽  
Proteolytic Enzymes ◽  
Mitochondrial Gene ◽  
Protective Action ◽  
Stress Conditions ◽  
Endogenous Protein ◽  
The Matrix ◽  
Beaten Track ◽  
Protein Quality Control System

To maintain organellar function, mitochondria contain an elaborate endogenous protein quality control system. As one of the two soluble energy-dependent proteolytic enzymes in the matrix compartment, the protease Lon is a major component of this system, responsible for the degradation of misfolded proteins, in particular under oxidative stress conditions. Lon defects have been shown to negatively affect energy production by oxidative phosphorylation but also mitochondrial gene expression. In this review, recent studies on the role of Lon in mammalian cells, in particular on its protective action under diverse stress conditions and its relationship to important human diseases are summarized and commented.

Minimum intron requirements for tRNA splicing and nuclear transport in Xenopus oocytes

Biochemistry ◽  
1993 ◽  
Vol 32 (33) ◽  
pp. 8575-8581 ◽  
Author(s):  
Rosalind C. Haselbeck ◽  
Chris L. Greer
Keyword(s):  
Xenopus Oocytes ◽  
Nuclear Transport ◽  
Trna Splicing

scholarly journals In vitro transport of a fluorescent nuclear protein and exclusion of non-nuclear proteins.

1986 ◽  
Vol 103 (6) ◽  
pp. 2091-2102 ◽  
Author(s):  
D D Newmeyer ◽  
D R Finlay ◽  
D J Forbes
Keyword(s):  
Low Temperature ◽  
Nuclear Protein ◽  
Transport Model ◽  
Nuclear Transport ◽  
Atp Depletion ◽  
Nuclear Proteins ◽  
Direct Role ◽  
In Vitro System

An in vitro system was developed that provides a quick microscopic assay for nuclear transport. The assay uses an extract of Xenopus eggs, normal or synthetic nuclei, and a fluorescently labeled nuclear protein, nucleoplasmin. This in vitro system accurately mimics in vivo nuclear transport, both in exclusivity and in the amount of accumulation observed (up to 17-fold). Selective accumulation of fluorescent nucleoplasmin is observed microscopically within 30 min with rat liver nuclei, Xenopus embryonic nuclei, regrown Xenopus sperm nuclei, or nuclei reconstituted in vitro from bacteriophage lambda DNA. This transport requires the signal domain of nucleoplasmin. Furthermore, the ability of nuclei to accumulate nucleoplasmin directly correlates with their ability to exclude the fluorescent non-nuclear proteins, FITC-immunoglobulin and phycoerythrin. An active transport model would predict that nuclear transport be temperature- and energy-dependent and that inhibition of transport by either low temperature or energy depletion would be reversible. Both predictions were confirmed in our system. Nucleoplasmin accumulation increases with temperature, while the protein is completely excluded at 0 degrees C. The effects of low temperature are reversible. As found for 125I-labeled nucleoplasmin (Newmeyer, D. D., J. M. Lucocq, T. R. Bürglin, and E. M. De Robertis, 1986, EMBO (Eur. Mol. Biol. Organ.) J., 5:501-510), transport of fluorescent nucleoplasmin is inhibited by ATP depletion. This effect is reversed by later ATP addition. Under ATP-depleted conditions non-nuclear proteins continue to be excluded. These results argue for a direct role of ATP in transport rather than for a simple role in preserving envelope integrity. In a first step towards defining the minimum requirements for a transport medium, egg extracts were depleted of membrane vesicles. Membrane-depleted extracts neither support transport nor maintain the integrity of the nuclear envelope.

scholarly journals Thermodynamic stability of G-quadruplex and overlapping m6A: Position-dependent collaborators in allele frequency and fitness?

2021 ◽  
Author(s):  
Cagri Gulec
Keyword(s):  
Statistical Analysis ◽  
Allele Frequency ◽  
Gene Product ◽  
Thermodynamic Stability ◽  
Rna Processing ◽  
Genetic Variants ◽  
Common Variants ◽  
Unequal Distribution ◽  
Human Genes ◽  
G Quadruplex

AbstractBackgroundPost-transcriptional modifications like m6A, and secondary structures like G-quadruplex (G4), play an important role in RNA processing. Despite an emerging number of studies focusing on m6A and G4 separately, there are less studies about their synergy.AimSince m6A is known to be enzymatically created in DRACH-motif, and genetic variants may create a novel DRACH-motif or abolish a pre-existing DRACH-motif, we can suppose that the variants may affect gene product level through modulating m6A-G4 colocalization, which consequently may affect fitness and change allele frequency. To test this hypothesis, rare and common variants in selected human genes were investigated in terms of their effect on m6A-G4 colocalization.MethodsGenomic sequences and variant features were fetched from GRCh37/hg19 and Biomart-Ensembl databases, respectively. Counting the number of putative m6A- and G4-motifs in sequences and statistical analysis were performed with appropriate libraries of Python3.7.ResultsCommon variants creating novel m6A-motif were found more frequently inside than outside G4, and displayed unequal distribution throughout pre-mRNA. Unequal distribution of m6A-creating variants seemed to be related to their effect on thermodynamic stability of the overlapping-G4.DiscussionSelective m6A-G4 colocalization suggests that m6A-motif is favorable when overlapping with G4. Besides, thermodynamic stability may lead to unequal distribution of m6A-G4 colocalization, because m6A-creating alleles seem to have lower frequency if stabilizes overlapping-G4 in 3-prime-side, but not in 5-prime-side. We can conclude that the fitness, and consequently frequency of an m6A-creating variant is prone to become higher or lower depending on its position and effect on the overlapping-G4 stability.

Abstract 34: A Human G109E Polymorphism in Inibitor-1 Compromises Cardiomyocyte Function and Induces Arrhythmias

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Kobra Haghighi ◽  
Tracy J Pritchard ◽  
Vivek P Singh ◽  
Parthib Das ◽  
Erica L Vanderbilt ◽  
...  
Keyword(s):  
Heart Failure ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Stress Conditions ◽  
Rat Cardiomyocytes ◽  
Promising Therapeutic Target ◽  
Endogenous Protein ◽  
Heart Failure Progression ◽  
Underlying Mechanisms

Protein phosphatase 1 (PP1) has emerged as a nodal regulator of function and survival in the heart. Indeed, the increased activity of this enzyme in failing hearts contributes to depressed SR Ca-cycling and deteriorative remodeling. PP1 is negatively regulated by endogenous inhibitor-1, which is considered a promising therapeutic target. Increases in inhibitor-1 activity and decreases in PP1 protect against ischemia/reperfusion injury, chronic isoproterenol stimulation and heart failure progression. We recently identified a polymorphism (G109E) in the inhibitor-1 gene in heart failure patients with a frequency of 6%. Expression of G109E (called mutant) in rat cardiomyocytes resulted in ~20% decreases in contractile parameters, Ca-transients and sarcoplasmic reticulum Ca-load. This depressed function was rescued by isoproterenol. Interestingly, when subjected to stress conditions (2 Hz +/- Iso), the mutant cells were more susceptible to aftercontractions. Similar findings were obtained by expression of G109E in inhibitor-1 knockout cardiomyocytes in the absence of endogenous protein. The underlying mechanisms included reduced binding of mutant to PP1, increased PP1 activity and hyper-phosphorylation of S2814 in ryanodine receptor (RyR), promoting aberrant SR Ca-release. These findings were also reflected by in vivo cardiac overexpression of G109E. Contractile and Ca-kinetic parameters were depressed by ~30% in mutant cardiomyocytes, while isoproterenol relieved these inhibitory effects. Stress conditions were associated with induction of Ca waves and aftercontractions in G109E cells. Furthermore, serial caffeine/Iso injections in vivo, elicited higher incidence of ventricular ectopy (bigeminy, trigeminy and non-sustained ventricular tachycardia) in mutant mice, whereas WTs had normal rhythm. Our findings suggest that G109E and increased PP1 may dephosphorylate the RyR and promote Ca-leak, in agreement with previous reports. Subsequently, the increased Ca-levels activate CAMK, leading to hyperphosphorylation of RyR and further increases in Ca-leak. Thus, inhibitor-1 is critical in cardiac function and represents a key control in balancing phosphatase/kinase activities to stabilize Ca-cycling in the heart.

Differential transport and integration into the nuclear lamina for lamins A, B, and C

1990 ◽  
Vol 68 (5) ◽  
pp. 827-831 ◽  
Author(s):  
André Dagenais ◽  
Andrée LeMyre ◽  
Viviane Bibor-Hardy
Keyword(s):  
Protein Synthesis ◽  
Nuclear Transport ◽  
Nuclear Lamina ◽  
High Salt ◽  
Nuclear Proteins ◽  
Cell Fractionation ◽  
Nonionic Detergent ◽  
In Vivo Labelling ◽  
Soluble Fractions

Lamins A, B, and C are the major proteins of the mammalian nuclear lamina and have been well studied in BHK-21 cells. Using in vivo labelling, cell fractionation, and immmunoprecipitation, we have found that lamins have different patterns of nuclear transport and solubility. Newly synthesized lamin A is translocated to the nucleus faster than lamin C or B. It is the most tightly bound lamin and cannot be extracted from the lamina by nonionic detergent or high-salt buffers. Lamins B and C migrate more slowly to the nucleus. Partitioning between cytoskeleton and detergent-soluble fractions shows that integration of lamins B and C is not completed before a 1-h chase. For lamin C this process is dependent upon protein synthesis and can be inhibited with cycloheximide. Even though lamins A and C are almost identical, lamin C is never firmly bound to the lamina and can be partially solubilized upon high-salt treatment.Key words: nuclear proteins, lamins, nuclear transport.

Nuclear transport of proteins translated in vitro from SP6 plasmid-generated mRNAs

1990 ◽  
Vol 10 (3) ◽  
pp. 1287-1292
Author(s):  
V K Parnaik ◽  
P K Kennady
Keyword(s):  
Dihydrofolate Reductase ◽  
Nuclear Transport ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Nuclear Proteins ◽  
In Vitro Translation ◽  
Nuclear Accumulation ◽  
Small T Antigen

A sensitive and versatile assay is described for the nuclear transport of 35S-labeled proteins obtained by the in vitro translation of SP6 plasmid-generated mRNAs. A specific nuclear accumulation of greater than 20-fold is observed for the transformation-related nuclear proteins, p53 and E1b, and the nuclear enzyme, thymidine kinase, whereas transport of the nonnuclear proteins, dihydrofolate reductase and simian virus 40 small t antigen, is negligible within 30 min.

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