scholarly journals FoxO6 transcriptional activity is regulated by Thr26 and Ser184, independent of nucleo-cytoplasmic shuttling

2005 ◽  
Vol 391 (3) ◽  
pp. 623-629 ◽  
Author(s):  
Lars P. van der Heide ◽  
Frank M. J. Jacobs ◽  
J. Peter H. Burbach ◽  
Marco F. M. Hoekman ◽  
Marten P. Smidt
Keyword(s):  
Transcription Factor ◽  
Growth Factors ◽  
Transcriptional Activity ◽  
Dependent Manner ◽  
Binding Characteristics ◽  
Forkhead Domain ◽  
Regulation Of Metabolism ◽  
Active Transcription ◽  
Phosphoinositide 3 Kinase ◽  
Constitutively Active

Forkhead members of the ‘O’ class (FoxO) are transcription factors crucial for the regulation of metabolism, cell cycle, cell death and cell survival. FoxO factors are regulated by insulin-mediated activation of PI3K (phosphoinositide 3-kinase)–PKB (protein kinase B) signalling. Activation of PI3K–PKB signalling results in the phosphorylation of FoxO factors on three conserved phosphorylation motifs, which are essential for the translocation of FoxO factors from the nucleus to the cytosol. FoxO6, however, remains mostly nuclear due to the fact that its shuttling ability is dramatically impaired. FoxO1, FoxO3 and FoxO4 all contain an N- and C-terminal PKB motif and a motif located in the forkhead domain. FoxO6 lacks the conserved C-terminal PKB motif, which is the cause of the shuttling impairment. Since FoxO6 can be considered constitutively nuclear, we investigated whether it is also a constitutively active transcription factor. Our results show that FoxO6 transcriptional activity is inhibited by growth factors, independent of shuttling, indicating that it is not constitutively active. The PKB site in the forkhead domain (Ser184) regulated the DNA binding characteristics and the N-terminal PKB site acted as a growth factor sensor. In summary, FoxO6 is not a constitutively active transcription factor and can be regulated by growth factors in a Thr26- and Ser184-dependent manner, independent of shuttling to the cytosol.

scholarly journals Parathyroid Hormone Increases Activating Transcription Factor 4 Expression and Activity in Osteoblasts: Requirement for Osteocalcin Gene Expression

Endocrinology ◽  
2008 ◽  
Vol 149 (4) ◽  
pp. 1960-1968 ◽  
Author(s):  
Shibing Yu ◽  
Renny T. Franceschi ◽  
Min Luo ◽  
Xiaoyan Zhang ◽  
Di Jiang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Protein Kinase ◽  
Transcriptional Activity ◽  
De Novo ◽  
Dependent Manner ◽  
Specific Element ◽  
Activating Transcription Factor 4 ◽  
Activating Transcription Factor ◽  
Transcription Factor 4 ◽  
Expression And Activity

PTH is an important peptide hormone regulator of calcium homeostasis and osteoblast function. However, its mechanism of action in osteoblasts is poorly understood. Our previous study demonstrated that PTH activates mouse osteocalcin (Ocn) gene 2 promoter through the osteoblast-specific element 1 site, a recently identified activating transcription factor-4 (ATF4) -binding element. In the present study, we examined effects of PTH on ATF4 expression and activity as well as the requirement for ATF4 in the regulation of Ocn by PTH. Results show that PTH elevated levels of ATF4 mRNA and protein in a dose- and time-dependent manner. This PTH regulation requires transcriptional activity but not de novo protein synthesis. PTH also increased binding of nuclear extracts to osteoblast-specific element 1 DNA. PTH stimulated ATF4-dependent transcriptional activity mainly through protein kinase A with a lesser requirement for protein kinase C and MAPK/ERK pathways. Lastly, PTH stimulation of Ocn expression was lost by small interfering RNA down-regulation of ATF4 in MC-4 cells and Atf4−/− bone marrow stromal cells. Collectively, these studies for the first time demonstrate that PTH increases ATF4 expression and activity and that ATF4 is required for PTH induction of Ocn expression in osteoblasts.

Abstract 267: Opposing Functions of Two Splice Variants of the Human Transcription Factor Grainyhead-like 3 in Endothelial Cells And in vivo

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Joachim Altschmied ◽  
Nicole Büchner ◽  
Sascha Jakob ◽  
Sabrina Farrokh ◽  
Christine Goy ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Target Genes ◽  
Splice Variants ◽  
Luciferase Reporter ◽  
Dependent Manner ◽  
Active Transcription ◽  
Human Transcription Factor

Grainyhead-like 3 (GRHL3) is a member of the evolutionary conserved Grainyhead family of transcription factors. In humans, three isoforms are derived from differential first exon usage and alternative splicing, which differ only in their N-terminus. Isoform 2, the only variant also present in mouse, is required for endothelial cell (EC) migration and protects against apoptosis. The functions of the human specific isoforms 1 and 3, which are derived from an alternatively spliced pre-mRNA, have not yet been investigated, although all three isoforms are expressed in EC. Therefore, we have assessed their effects on EC migration and apoptosis. Overexpression of the two proteins had opposite effects on EC migration, with isoform 1 acting pro-migratory. This protein also protected EC against apoptosis in an eNOS-dependent manner, whereas isoform 3 had no effect. These opposing outcomes with respect to apoptosis EC were corroborated by isoform-specific knockdowns. With reporter assays using a GRHL3-specific luciferase reporter we demonstrated that both are active transcription factors. Microarray analyses revealed that they induce divergent target gene sets in EC. Two validated targets, Akt2 and Mxi1, which are upregulated by isoform1, are regulators of Akt1-, and thus eNOS-phosphorylation and apoptosis, which could explain the effects of this protein on these processes. In vivo, overexpression of isoform 3 in zebrafish embryos resulted in increased lethality and severe deformations, while isoform 1 had no deleterious effect. In conclusion, our data demonstrate that the splice variant derived isoforms 1 and 3 of the human transcription factor GRHL3 induce opposing effects in primary human endothelial cells and in a whole animal model, most likely through the induction of different target genes.

scholarly journals Recruitment of Dioxin Receptor to Active Transcription Sites

2002 ◽  
Vol 13 (6) ◽  
pp. 2001-2015 ◽  
Author(s):  
Cem Elbi ◽  
Tom Misteli ◽  
Gordon L. Hager
Keyword(s):  
Transcription Factor ◽  
Target Genes ◽  
Biological Effects ◽  
Dependent Manner ◽  
Regulatory Domains ◽  
Aryl Hydrocarbon ◽  
Transcription Sites ◽  
Active Transcription ◽  
Ligand Stimulation ◽  
Dioxin Receptor

The aryl hydrocarbon receptor (AhR or dioxin receptor) is a ligand-activated transcription factor that heterodimerizes with the AhR nuclear translocator (ARNT/HIF-1β) to form an AhR/ARNT transcription factor complex. This complex binds to specific DNA sites in the regulatory domains of numerous target genes and mediates the biological effects of exogenous ligands. Herein, we have investigated the subcellular distribution of the AhR/ARNT complex in response to ligand stimulation, by using live-cell confocal and high-resolution deconvolution microscopy. We found that unliganded AhR shows a predominantly cytoplasmic diffuse distribution in mouse hepatoma cells. On addition of ligand, AhR rapidly translocates to the nucleus and accumulates in multiple bright foci. Inhibition of transcription prevented the formation of AhR foci. Dual- and triple-immunolabeling experiments, combined with labeling of nascent RNA, showed that the foci are transcription sites, indicating that upon ligand stimulation, AhR is recruited to active transcription sites. The interaction of AhR with ARNT was both necessary and sufficient for the recruitment of AhR to transcription sites. These results indicate that AhR/ARNT complexes are recruited to specific subnuclear compartments in a ligand-dependent manner and that these foci represent the sites of AhR target genes.

scholarly journals A pathogenic DYT-THAP1 dystonia mutation causes hypomyelination and loss of YY1 binding

2021 ◽  
Author(s):  
Dhananjay Yellajoshyula ◽  
Abigail E Rogers ◽  
Audrey J Kim ◽  
Sumin Kim ◽  
Samuel S Pappas ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Missense Mutation ◽  
Transcriptional Activity ◽  
Molecular Pathogenesis ◽  
Active Transcription ◽  
Cns Myelination ◽  
Established Role

Dystonia is a disabling disease that manifests as prolonged involuntary twisting movements. DYT-THAP1 is an inherited form of isolated dystonia caused by mutations in THAP1 encoding the transcription factor THAP1. The phe81leu (F81L) missense mutation is representative of a category of poorly understood mutations that do not occur on residues critical for DNA binding. Here, we demonstrate that the F81L mutation (THAP1F81L) impairs THAP1 transcriptional activity and disrupts CNS myelination. Strikingly, THAP1F81L exhibits normal DNA binding but causes a significantly reduced DNA binding of YY1, its transcriptional partner that also has an established role in oligodendrocyte lineage progression. Our results suggest a model of molecular pathogenesis whereby THAP1F81L normally binds DNA but is unable to efficiently organize an active transcription complex.

scholarly journals MiT/TFE transcription factors are activated during mitophagy downstream of Parkin and Atg5

2015 ◽  
Vol 210 (3) ◽  
pp. 435-450 ◽  
Author(s):  
Catherine L. Nezich ◽  
Chunxin Wang ◽  
Adam I. Fogel ◽  
Richard J. Youle
Keyword(s):  
Transcription Factor ◽  
Transcriptional Activity ◽  
Mammalian Target Of Rapamycin ◽  
Dependent Manner ◽  
Transcription Factor Activation ◽  
Selective Elimination ◽  
Pathways Analysis ◽  
Transcription Factor Eb ◽  
Microphthalmia Transcription Factor ◽  
Activation Pathways

The kinase PINK1 and ubiquitin ligase Parkin can regulate the selective elimination of damaged mitochondria through autophagy (mitophagy). Because of the demand on lysosomal function by mitophagy, we investigated a role for the transcription factor EB (TFEB), a master regulator of lysosomal biogenesis, in this process. We show that during mitophagy TFEB translocates to the nucleus and displays transcriptional activity in a PINK1- and Parkin-dependent manner. MITF and TFE3, homologues of TFEB belonging to the same microphthalmia/transcription factor E (MiT/TFE) family, are similarly regulated during mitophagy. Unlike TFEB translocation after starvation-induced mammalian target of rapamycin complex 1 inhibition, Parkin-mediated TFEB relocalization required Atg9A and Atg5 activity. However, constitutively active Rag guanosine triphosphatases prevented TFEB translocation during mitophagy, suggesting cross talk between these two MiT/TFE activation pathways. Analysis of clustered regularly interspaced short palindromic repeats–generated TFEB/MITF/TFE3/TFEC single, double, and triple knockout cell lines revealed that these proteins partly facilitate Parkin-mediated mitochondrial clearance. These results illuminate a pathway leading to MiT/TFE transcription factor activation, distinct from starvation-induced autophagy, which occurs during mitophagy.

scholarly journals Fluctuations in AKT and PTEN Activity Are Linked by the E3 Ubiquitin Ligase cCBL

Cells ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2803
Author(s):  
Manuel Olazábal-Morán ◽  
Miriam Sánchez-Ortega ◽  
Laura Martínez-Muñoz ◽  
Carmen Hernández ◽  
Manuel S. Rodríguez ◽  
...  
Keyword(s):  
Growth Factors ◽  
Interaction Analysis ◽  
Pi3 Kinase ◽  
Dependent Manner ◽  
Protein Protein Interaction ◽  
Tensin Homolog ◽  
Ubiquitin E3 Ligase ◽  
B Lineage ◽  
And Migration ◽  
Phosphoinositide 3 Kinase

3-poly-phosphoinositides (PIP3) regulate cell survival, division, and migration. Both PI3-kinase (phosphoinositide-3-kinase) and PTEN (phosphatase and tensin-homolog in chromosome 10) control PIP3 levels, but the mechanisms connecting PI3-kinase and PTEN are unknown. Using non-transformed cells, the activation kinetics of PTEN and of the PIP3-effector AKT were examined after the addition of growth factors. Both epidermal growth factor and serum induced the early activation of AKT and the simultaneous inactivation of PTEN (at ~5 min). This PIP3/AKT peak was followed by a general reduction in AKT activity coincident with the recovery of PTEN phosphatase activity (at ~10–15 min). Subsequent AKT peaks and troughs followed. The fluctuation in AKT activity was linked to that of PTEN; PTEN reconstitution in PTEN-null cells restored AKT fluctuations, while PTEN depletion in control cells abrogated them. The analysis of PTEN activity fluctuations after the addition of growth factors showed its inactivation at ~5 min to be simultaneous with its transient ubiquitination, which was regulated by the ubiquitin E3 ligase cCBL (casitas B-lineage lymphoma proto-oncogene). Protein-protein interaction analysis revealed cCBL to be brought into the proximity of PTEN in a PI3-kinase-dependent manner. These results reveal a mechanism for PI3-kinase/PTEN crosstalk and suggest that cCBL could be new target in strategies designed to modulate PTEN activity in cancer.

PTEN interacts with metal-responsive transcription factor 1 and stimulates its transcriptional activity

2011 ◽  
Vol 441 (1) ◽  
pp. 367-377 ◽  
Author(s):  
Meng-Chieh Lin ◽  
Ya-Chuan Liu ◽  
Ming F. Tam ◽  
Yu-Ju Lu ◽  
Ya-Ting Hsieh ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Nuclear Translocation ◽  
Cadmium Toxicity ◽  
Binding Activity ◽  
Dependent Manner ◽  
Dna Binding Activity ◽  
Expression Of Genes ◽  
Zinc Addition ◽  
Phosphoinositide 3 Kinase ◽  
Transcription Factor 1

MTF-1 (metal-responsive transcription factor 1) is an essential mammalian protein for embryonic development and modulates the expression of genes involving in zinc homoeostasis and responding to oxidative stress. We report in the present paper that PTEN (phosphatase and tensin homologue deleted on chromosome 10) associates with MTF-1 in the cells. These two proteins interact via the acidic domain of MTF-1 and the phosphatase/C2 domain of PTEN. Depletion of PTEN reduced MT (metallothionein) gene expression and increased cellular sensitivity to cadmium toxicity. PTEN did not alter the nuclear translocation, protein stability or DNA-binding activity of MTF-1. Zinc increased MTF-1–PTEN interaction in a dose-dependent manner. The interaction elevated within 2 h of zinc addition and declined afterwards in the cells. The enhanced binding activity occurred mainly in the cytoplasm and reduced after translocating the MTF-1 into the nucleus. Blocking signalling through the PI3K (phosphoinositide 3-kinase) pathway did not alter the zinc-induced MT expression. Analysis of enzymatically inactive PTEN mutants demonstrated that protein but not lipid phosphatase activity of PTEN was involved in the regulation of MTF-1 activity. The same regulatory role of PTEN was also noted in the regulation of ZnT1 (zinc transporter 1), another target gene of MTF-1.

The Anti-Atherogenic Properties of Sesamin are Mediated via Improved Macrophage Cholesterol Efflux Through PPARγ1-LXRα and MAPK Signaling

2014 ◽  
Vol 84 (1-2) ◽  
pp. 79-91 ◽  
Author(s):  
Amin F. Majdalawieh ◽  
Hyo-Sung Ro
Keyword(s):  
Cholesterol Efflux ◽  
Transcriptional Activity ◽  
Molecular Mechanisms ◽  
Foam Cell ◽  
Mapk Signaling ◽  
Luciferase Reporter ◽  
Foam Cell Formation ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Macrophage Cholesterol Efflux

Background: Foam cell formation resulting from disrupted macrophage cholesterol efflux, which is triggered by PPARγ1 and LXRα, is a hallmark of atherosclerosis. Sesamin and sesame oil exert anti-atherogenic effects in vivo. However, the exact molecular mechanisms underlying such effects are not fully understood. Aim: This study examines the potential effects of sesamin (0, 25, 50, 75, 100 μM) on PPARγ1 and LXRα expression and transcriptional activity as well as macrophage cholesterol efflux. Methods: PPARγ1 and LXRα expression and transcriptional activity are assessed by luciferase reporter assays. Macrophage cholesterol efflux is evaluated by ApoAI-specific cholesterol efflux assays. Results: The 50 μM, 75 μM, and 100 μM concentrations of sesamin up-regulated the expression of PPARγ1 (p< 0.001, p < 0.001, p < 0.001, respectively) and LXRα (p = 0.002, p < 0.001, p < 0.001, respectively) in a concentration-dependent manner. Moreover, 75 μM and 100 μM concentrations of sesamin led to 5.2-fold (p < 0.001) and 6.0-fold (p<0.001) increases in PPAR transcriptional activity and 3.9-fold (p< 0.001) and 4.2-fold (p < 0.001) increases in LXR transcriptional activity, respectively, in a concentration- and time-dependent manner via MAPK signaling. Consistently, 50 μM, 75 μM, and 100 μM concentrations of sesamin improved macrophage cholesterol efflux by 2.7-fold (p < 0.001), 4.2-fold (p < 0.001), and 4.2-fold (p < 0.001), respectively, via MAPK signaling. Conclusion: Our findings shed light on the molecular mechanism(s) underlying sesamin’s anti-atherogenic effects, which seem to be due, at least in part, to its ability to up-regulate PPARγ1 and LXRα expression and transcriptional activity, improving macrophage cholesterol efflux. We anticipate that sesamin may be used as a therapeutic agent for treating atherosclerosis.

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