scholarly journals Mechanism Underlying the Iron-dependent Nuclear Export of the Iron-responsive Transcription Factor Aft1p in Saccharomyces cerevisiae

2007 ◽  
Vol 18 (8) ◽  
pp. 2980-2990 ◽  
Author(s):  
Ryo Ueta ◽  
Naoko Fujiwara ◽  
Kazuhiro Iwai ◽  
Yuko Yamaguchi-Iwai
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Intermolecular Interaction ◽  
Nuclear Import ◽  
Nuclear Export ◽  
Iron Homeostasis ◽  
Target Genes ◽  
Critical Role ◽  
Dependent Manner ◽  
Constitutive Activation ◽  
Nuclear Export Receptor

Aft1p is an iron-responsive transcriptional activator that plays a central role in maintaining iron homeostasis in Saccharomyces cerevisiae. Aft1p is regulated primarily by iron-induced shuttling of the protein between the nucleus and cytoplasm, but its nuclear import is not regulated by iron. Here, we have shown that the nuclear export of Aft1p is promoted in the presence of iron and that Msn5p is the nuclear export receptor (exportin) for Aft1p. Msn5p recognizes Aft1p in the iron-replete condition. Phosphorylation of S210 and S224 in Aft1p, which is not iron dependent, and the iron-induced intermolecular interaction of Aft1p are both essential for its recognition by Msn5p. Mutation of Cys291 of Aft1p to Phe, which causes Aft1p to be retained in the nucleus and results in constitutive activation of Aft1-target genes, disrupts the intermolecular interaction of Aft1p. Collectively, these results suggest that iron induces a conformational change in Aft1p, in which Aft1p Cys291 plays a critical role, and that, in turn, Aft1p is recognized by Msn5p and exported into the cytoplasm in an iron-dependent manner.

scholarly journals Nuclear Import of IκBα Is Accomplished by a Ran-Independent Transport Pathway

2000 ◽  
Vol 20 (5) ◽  
pp. 1571-1582 ◽  
Author(s):  
Shrikesh Sachdev ◽  
Sriparna Bagchi ◽  
Donna D. Zhang ◽  
Angela C. Mings ◽  
Mark Hannink
Keyword(s):  
Nuclear Import ◽  
Nuclear Export ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Nuclear Pore ◽  
Transport Pathway ◽  
Repeat Domain ◽  
Nuclear Export Receptor

ABSTRACT The inhibitor of kappa B alpha (IκBα) protein is able to shuttle between the cytoplasm and the nucleus. We have utilized a combination of in vivo and in vitro approaches to provide mechanistic insight into nucleocytoplasmic shuttling by IκBα. IκBα contains multiple functional domains that contribute to shuttling of IκBα between the cytoplasm and the nucleus. Nuclear import of IκBα is mediated by the central ankyrin repeat domain. Similar to previously described nuclear import pathways, nuclear import of IκBα is temperature and ATP dependent and is blocked by a dominant-negative mutant of importin β. However, in contrast to classical nuclear import pathways, nuclear import of IκBα is independent of soluble cytosolic factors and is not blocked by the dominant-negative RanQ69L protein. Nuclear export of IκBα is mediated by an N-terminal nuclear export sequence. Nuclear export of IκBα requires the CRM1 nuclear export receptor and is blocked by the dominant-negative RanQ69L protein. Our results are consistent with a model in which nuclear import of IκBα is mediated through direct interactions with components of the nuclear pore complex, while nuclear export of IκBα is mediated via a CRM1-dependent pathway.

Effect of fluoride on PERK-Nrf2 signaling pathway in mouse ameloblasts

2019 ◽  
Vol 38 (7) ◽  
pp. 833-845
Author(s):  
X Zhou ◽  
Z Chen ◽  
W Zhong ◽  
R Yu ◽  
L He
Keyword(s):  
Oxidative Stress ◽  
Er Stress ◽  
Signaling Pathway ◽  
Nuclear Import ◽  
Target Genes ◽  
Dental Fluorosis ◽  
Related Factor ◽  
Dependent Manner ◽  
Nrf2 Signaling Pathway ◽  
Glutamylcysteine Synthetase

In the development of dental fluorosis, oxidative stress is considered as the key mechanism. Endoplasmic reticulum (ER) stress can induce oxidative stress and activate the important antioxidative factor nuclear factor erythroid 2-related factor 2 (Nrf2) in a PKR-like ER kinase (PERK)-dependent manner, but combining ER stress and oxidative stress, the role of PERK-Nrf2 signaling pathway involved in fluoride-regulated ameloblasts is not fully defined. Here, we studied the effect of fluoride on PERK-Nrf2 signaling pathway in mouse ameloblasts. We found that low-dose and continuous fluoride exposure increased binding immunoglobulin protein expression and activated PERK–activating transcription factor 4 signaling pathway. Meanwhile, the expression of Nrf2 and its target genes (glutamylcysteine synthetase and glutathione S-transferase-P1) enhanced following ER stress. Tunicamycin increased the expression of PERK, leading to Nrf2 nuclear import, and tauroursodeoxycholate suppressed Nrf2 activation through PERK during ER stress, indicating that PERK activation is required for Nrf2 nuclear entry. Furthermore, tert-butylhydroquinone triggered the overexpression of Nrf2 to reduce ER stress, but luteolin inhibited Nrf2 nuclear localization to elevate ER stress. In summary, this study proved that fluoride under certain dose can induce ER stress and promote Nrf2 nuclear import via PERK activation and suggested that antioxidation mechanism mediated by PERK-Nrf2 can alleviate fluoride-induced ER stress effectively.

scholarly journals Cytosolic Hsp70 and co-chaperones constitute a novel system for tRNA import into the nucleus

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Akira Takano ◽  
Takuya Kajita ◽  
Makoto Mochizuki ◽  
Toshiya Endo ◽  
Tohru Yoshihisa
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Quality Control ◽  
Nuclear Import ◽  
Nuclear Export ◽  
Substrate Recognition ◽  
Structural Features ◽  
Nuclear Accumulation ◽  
Nucleotide Binding Domain ◽  
Trna Import ◽  
Trna Binding

tRNAs are unique among various RNAs in that they shuttle between the nucleus and the cytoplasm, and their localization is regulated by nutrient conditions. Although nuclear export of tRNAs has been well documented, the import machinery is poorly understood. Here, we identified Ssa2p, a major cytoplasmic Hsp70 in Saccharomyces cerevisiae, as a tRNA-binding protein whose deletion compromises nuclear accumulation of tRNAs upon nutrient starvation. Ssa2p recognizes several structural features of tRNAs through its nucleotide-binding domain, but prefers loosely-folded tRNAs, suggesting that Ssa2p has a chaperone-like activity for RNAs. Ssa2p also binds Nup116, one of the yeast nucleoporins. Sis1p and Ydj1p, cytoplasmic co-chaperones for Ssa proteins, were also found to contribute to the tRNA import. These results unveil a novel function of the Ssa2p system as a tRNA carrier for nuclear import by a novel mode of substrate recognition. Such Ssa2p-mediated tRNA import likely contributes to quality control of cytosolic tRNAs.

scholarly journals The Mobile FG Nucleoporin Nup98 Is a Cofactor for Crm1-dependent Protein Export

2010 ◽  
Vol 21 (11) ◽  
pp. 1885-1896 ◽  
Author(s):  
Masahiro Oka ◽  
Munehiro Asally ◽  
Yoshinari Yasuda ◽  
Yutaka Ogawa ◽  
Taro Tachibana ◽  
...  
Keyword(s):  
Nuclear Export ◽  
Nuclear Protein ◽  
Mutational Analysis ◽  
Specific Inhibitor ◽  
Protein Export ◽  
Dependent Manner ◽  
Repeat Region ◽  
Leptomycin B ◽  
Dependent Protein ◽  
Nuclear Export Receptor

Nup98 is a mobile nucleoporin that forms distinct dots in the nucleus, and, although a role for Nup98 in nuclear transport has been suggested, its precise function remains unclear. Here, we show that Nup98 plays an important role in Crm1-mediated nuclear protein export. Nuclear, but not cytoplasmic, dots of EGFP-tagged Nup98 disappeared rapidly after cell treatment with leptomycin B, a specific inhibitor of the nuclear export receptor, Crm1. Mutational analysis demonstrated that Nup98 physically and functionally interacts with Crm1 in a RanGTP-dependent manner through its N-terminal phenylalanine-glycine (FG) repeat region. Moreover, the activity of the Nup98-Crm1 complex was modulated by RanBP3, a known cofactor for Crm1-mediated nuclear export. Finally, cytoplasmic microinjection of anti-Nup98 inhibited the Crm1-dependent nuclear export of proteins, concomitant with the accumulation of anti-Nup98 in the nucleus. These results clearly demonstrate that Nup98 functions as a novel shuttling cofactor for Crm1-mediated nuclear export in conjunction with RanBP3.

scholarly journals Insulin regulates menin expression, cytoplasmic localization, and interaction with FOXO1

2011 ◽  
Vol 301 (3) ◽  
pp. E474-E483 ◽  
Author(s):  
Leah Wuescher ◽  
Kristine Angevine ◽  
Terry Hinds ◽  
Sadeesh Ramakrishnan ◽  
Sonia M. Najjar ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Target Genes ◽  
Serum Insulin ◽  
Critical Role ◽  
Early Time ◽  
Protein Product ◽  
Dependent Manner ◽  
Cytoplasmic Localization ◽  
Akt Inhibitor ◽  
Human Insulin Receptor

Menin is the ubiquitously expressed nuclear protein product of the MEN1 gene, which interacts with PKB/Akt in the cytoplasm to inhibit its activity. This study describes a novel insulin-dependent mechanism of menin regulation and interaction with other metabolic proteins. We show that insulin downregulated menin in a time-dependent manner via the human insulin receptor. Inhibition analysis indicated a critical role for the protein kinase Akt in regulation of menin expression and localization. Insulin-mediated decrease in menin expression was abrogated by the PI3K/Akt inhibitor LY-294002 at early time points, from 2 to 7 h. Furthermore, exposure to insulin resulted in the cytoplasmic localization of menin and increased interaction with FOXO1. Fasting followed by refeeding modulates serum insulin levels, which corresponded to an increase in menin interaction with FOXO1 in the liver. Liver-specific hemizygous deletion of menin resulted in increased expression of FOXO1 target genes, namely IGFBP-1, PGC-1α, insulin receptor, Akt, and G-6-Pase. This study provides evidence that menin expression and localization are regulated by insulin signaling and that this regulation triggers an increase in its interaction with FOXO1 via Akt with metabolic consequences.

scholarly journals Fzf1p Regulates an Inducible Response to Nitrosative Stress in Saccharomyces cerevisiae

2005 ◽  
Vol 16 (10) ◽  
pp. 4781-4791 ◽  
Author(s):  
Aaron Sarver ◽  
Joseph DeRisi
Keyword(s):  
Nitric Oxide ◽  
Saccharomyces Cerevisiae ◽  
Target Genes ◽  
Nitrosative Stress ◽  
Transcriptional Response ◽  
Open Reading Frames ◽  
Specific Response ◽  
Dependent Manner ◽  
Promoter Regions ◽  
Transcriptional Induction

The mechanisms by which microorganisms sense and detoxify nitric oxide (.NO) are of particular interest due to the central role this molecule plays in innate immunity. We investigated the genetic basis of inducible nitric oxide (.NO) detoxification in Saccharomyces cerevisiae by characterizing the genome-wide transcriptional response to exogenously supplied .NO. Exposure to the .NO-generating compound dipropylenetriamine NONOate resulted in both a general stress response as well as a specific response characterized by the induction of a small set of genes, including the yeast flavohemoglobin YHB1, SSU1, and three additional uncharacterized open reading frames. Transcriptional induction of SSU1, which encodes a putative sulfite transporter, has previously been shown to require the zinc finger transcription factor Fzf1p. Deletion of Fzf1p eliminated the nitrosative stress-specific transcriptional response, whereas overexpression of Fzf1p recapitulated this response in the absence of exogenously supplied .NO. A cis-acting sequence unique to the promoter regions of Fzf1p-dependent genes was found to be sufficient to activate reporter gene activity in an .NO- and Fzf1p-dependent manner. Our results suggest that the presence of .NO or .NO derivatives activates Fzf1p leading to transcriptional induction of a discrete set of target genes that function to protect the cell from .NO-mediated stress.

scholarly journals Modulation of the canonical Wnt activity by androgen signaling in prostate epithelial basal stem cells

2020 ◽  
Author(s):  
Yueli Liu ◽  
Jiawen Wang ◽  
Corrigan Horton ◽  
Sol Katzman ◽  
Tao Cai ◽  
...  
Keyword(s):  
Stem Cell ◽  
Wnt Signaling ◽  
Target Genes ◽  
Critical Role ◽  
Gene Set Enrichment Analysis ◽  
Dependent Manner ◽  
Basal Cells ◽  
Canonical Wnt Signaling ◽  
Cell Functions ◽  
Canonical Wnt

AbstractBoth the canonical Wnt signaling and androgen signaling are important factors regulating prostate organogenesis. How these two pathways crosstalk to regulate prostate stem cell functions remain unclear. Here, we show that while canonical Wnt activity is required for prostate basal stem cell multipotency in vivo, ectopic Wnt activity does not promote basal-to-luminal cell differentiation. We provide evidence that androgen signaling may keep Wnt activity in check. In prostate organoid culture from basal cells, dihydrotestosterone (DHT) antagonizes R-spondin-stimulated organoid growth in a concentration-dependent manner. Molecular analyses of organoids under different treatment conditions showed that androgen signaling down-regulated the expressions of a Wnt reporter as well as many Wnt target genes. Pathway analysis and gene set enrichment analysis of organoid RNA-seq data also revealed the canonical Wnt signaling as a key pathway distinguishing organoids treated with or without DHT. Notably, DHT treatment enhanced AR and β–catenin binding in the nuclei of prostate organoids, providing possible mechanistic clues. Our results reveal a critical role of AR signaling in modulating canonical Wnt activity in prostate basal cells to regulate their multipotency.

scholarly journals Arx1 Is a Nuclear Export Receptor for the 60S Ribosomal Subunit in Yeast

2008 ◽  
Vol 19 (2) ◽  
pp. 735-744 ◽  
Author(s):  
Nai-Jung Hung ◽  
Kai-Yin Lo ◽  
Samir S. Patel ◽  
Kara Helmke ◽  
Arlen W. Johnson
Keyword(s):  
Nuclear Export ◽  
Ribosomal Subunit ◽  
In Vitro Assays ◽  
Dependent Manner ◽  
Yeast Two Hybrid ◽  
Synthetic Lethal ◽  
Nuclear Export Receptor ◽  
Export Receptors ◽  
Two Hybrid

We previously showed that nuclear export of the large (60S) ribosomal subunit relies on Nmd3 in a Crm1-dependent manner. Recently the general mRNA export factor, the Mtr2/Mex67 heterodimer, was shown to act as an export receptor in parallel with Crm1. These observations raise the possibility that nuclear export of the 60S subunit in Saccharomyces cerevisiae requires multiple export receptors. Here, we show that the previously characterized 60S subunit biogenesis factor, Arx1, also acts as an export receptor for the 60S subunit. We found that deletion of ARX1 was synthetic lethal with nmd3 and mtr2 mutants and was synthetic sick with several nucleoporin mutants. Deletion of ARX1 led to accumulation of pre-60S particles in the nucleus that were enriched for Nmd3, Crm1, Mex67, and Mtr2, suggesting that in the absence of Arx1, 60S export is impaired even though the subunit is loaded with export receptors. Finally, Arx1 interacted with several nucleoporins in yeast two-hybrid as well as in vitro assays. These results show that Arx1 can directly bridge the interaction between the pre-60S particle and the NPC and thus is a third export receptor for the 60S subunit in yeast.

scholarly journals Phosphorylation-dependent Regnase-1 release from endoplasmic reticulum is critical in IL-17 response

2019 ◽  
Vol 216 (6) ◽  
pp. 1431-1449 ◽  
Author(s):  
Hiroki Tanaka ◽  
Yasunobu Arima ◽  
Daisuke Kamimura ◽  
Yuki Tanaka ◽  
Noriyuki Takahashi ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Target Genes ◽  
Inflammatory Diseases ◽  
Critical Role ◽  
Mrna Degradation ◽  
Mutant Mice ◽  
Dependent Manner ◽  
T Helper 17 ◽  
External Stimuli

Regnase-1 (also known as Zc3h12a or MCPIP-1) is an endoribonuclease involved in mRNA degradation of inflammation-associated genes. Regnase-1 is inactivated in response to external stimuli through post-translational modifications including phosphorylation, yet the precise role of phosphorylation remains unknown. Here, we demonstrate that interleukin (IL)-17 induces phosphorylation of Regnase-1 in an Act1-TBK1/IKKi–dependent manner, especially in nonhematopoietic cells. Phosphorylated Regnase-1 is released from the endoplasmic reticulum (ER) into the cytosol, thereby losing its mRNA degradation function, which leads to expression of IL-17 target genes. By using CRISPR/Cas-9 technology, we generated Regnase-1 mutant mice, in which IL-17–induced Regnase-1 phosphorylation is completely blocked. Mutant mice (Regnase-1AA/AA and Regnase-1ΔCTD/ΔCTD) were resistant to the IL-17–mediated inflammation caused by T helper 17 (Th17) cells in vivo. Thus, Regnase-1 plays a critical role in the development of IL-17–mediated inflammatory diseases via the Act1-TBK1-IKKi axis, and blockade of Regnase-1 phosphorylation sites may be promising for treatment of Th17-associated diseases.

scholarly journals Swift Is a Novel BRCT Domain Coactivator of Smad2 in Transforming Growth Factor β Signaling

2001 ◽  
Vol 21 (12) ◽  
pp. 3901-3912 ◽  
Author(s):  
Kazuya Shimizu ◽  
Pierre-Yves Bourillot ◽  
Søren J. Nielsen ◽  
Aaron M. Zorn ◽  
J. B. Gurdon
Keyword(s):  
Growth Factor ◽  
Gene Transcription ◽  
Target Genes ◽  
Transforming Growth Factor ◽  
Critical Role ◽  
Gene Activation ◽  
Transforming Growth Factor Β ◽  
Growth Factor Signaling ◽  
Dependent Manner ◽  
Tgfβ Signaling

ABSTRACT Transforming growth factor β (TGFβ) signaling is transduced via Smad2–Smad4–DNA-binding protein complexes which bind to responsive elements in the promoters of target genes. However, the mechanism of how the complexes activate the target genes is unclear. Here we identify Xenopus Swift, a novel nuclear BRCT (BRCA1 C-terminal) domain protein that physically interacts with Smad2 via its BRCT domains. We examine the activity of Swift in relation to gene activation in Xenopus embryos. Swift mRNA has an expression pattern similar to that of Smad2. Swift has intrinsic transactivation activity and activates target gene transcription in a TGFβ-Smad2-dependent manner. Inhibition of Swift activity results in the suppression of TGFβ-induced gene transcription and defective mesendoderm development. Blocking Swift function affects neither bone morphogenic protein nor fibroblast growth factor signaling during early development. We conclude that Swift is a novel coactivator of Smad2 and that Swift has a critical role in embryonic TGFβ-induced gene transcription. Our results suggest that Swift may be a general component of TGFβ signaling.

Sign in / Sign up

Export Citation Format

Share Document