Despite its strong transactivation domain, transcription factor FOXM1c is kept almost inactive by two different inhibitory domains

2006 ◽  
Vol 387 (7) ◽  
pp. 963-976 ◽  
Author(s):  
Inken Wierstra ◽  
Jürgen Alves
Keyword(s):  
Transcription Factor ◽  
Transactivation Domain ◽  
Regulatory Domain ◽  
Central Domain ◽  
Nuclear Localization Signals ◽  
Forkhead Domain ◽  
N Terminus ◽  
Activating Transcription Factor ◽  
Very High

Abstract FOXM1c (MPP2) is an activating transcription factor with several nuclear localization signals, a forkhead domain for DNA binding, and a very strong acidic transactivation domain. Despite its very strong transactivation domain, FOXM1c is kept almost inactive by two different independent inhibitory domains, the N-terminus and the central domain. The N-terminus as a specific negative-regulatory domain directly binds to and thus inhibits the transactivation domain completely. However, it lacks any transrepression potential. In contrast, the central domain functions as a strong RB-independent transrepression domain and as an RB-recruiting negative-regulatory domain. The N-terminus alone is sufficient to eliminate transactivation, while the central domain alone represses the transactivation domain only partially. This hierarchy of the two inhibitory domains offers the possibility to activate the almost inactive wild type in two steps in vitro: deletion of the N-terminus results in a strong transactivator, while additional deletion of the central domain in a very strong transactivator. We suggest that the very high potential of the transactivation domain has to be tightly controlled by these two inhibitory domains because FOXM1 stimulates proliferation by promoting G1/S transition, as well as G2/M transition, and because deregulation of such potent activators of proliferation can result in tumorigenesis.

scholarly journals Protease Inhibitor Anti-HIV, Lopinavir, Impairs Placental Endocrine Function

2021 ◽  
Vol 22 (2) ◽  
pp. 683
Author(s):  
Camille Fraichard ◽  
Fidéline Bonnet-Serrano ◽  
Christelle Laguillier-Morizot ◽  
Marylise Hebert-Schuster ◽  
René Lai-Kuen ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Metastatic Lymph Node ◽  
Endocrine Function ◽  
Maternal Circulation ◽  
Hormone Production ◽  
Mitofusin 2 ◽  
Villous Trophoblast ◽  
Activating Transcription Factor ◽  
Upr Pathway

Protease Inhibitors (PI e.g., ritonavir (RTV) and lopinavir (LPV)) used to treat pregnant mothers infected by HIV induce prematurity and endocrine dysfunctions. The maintenance of pregnancy relies on placental hormone production (human Chorionic Gonadotrophin (hCG) and progesterone (P4)). Those functions are ensured by the villous trophoblast and are mainly regulated by the Unfolded Protein Response (UPR) pathway and mitochondria. We investigated, in vitro, if PI impair hCG and P4 production and the potential intracellular mechanisms involved. Term villous cytotrophoblast (VCT) were cultured with or without RTV or LPV from 6 to 48 h. VCT differentiation into syncytiotrophoblast (ST) was followed measuring hCG and P4 secretion. We evaluated the expression of P4 synthesis partners (Metastatic Lymph Node 64 (MLN64), cholesterol side-chain cleavage (P450SCC), Hydroxy-delta-5-Steroid Dehydrogenase and 3 Beta-and steroid delta-isomerase 1 (HSD3B1)), of mitochondrial pro-fusion factors (Mitofusin 2 (Mfn2), Optic Atrophy 1 (OPA1)) and of UPR factors (Glucose-Regulated Protein 78 (GRP78), Activating Transcription Factor 4 (ATF4), Activating Transcription Factor 6 (ATF6), spliced X-box Binding Protein 1 (sXBP1)). RTV had no significant effect on hCG and P4 secretion, whereas lopinavir significantly decreased both secretions. LPV also decreased P450SCC and HSD3B1 expression, whereas it increased Mfn2, GRP78 and sXBP1 expression in ST. RTV has no effect on the endocrine placenta. LPV impairs both villous trophoblast differentiation and P4 production. It is likely to act via mitochondrial fusion and UPR pathway activation. These trophoblastic alterations may end in decreased P4 levels in maternal circulation, inducing prematurity.

scholarly journals Erythroid-cell-specific properties of transcription factor GATA-1 revealed by phenotypic rescue of a gene-targeted cell line.

1997 ◽  
Vol 17 (3) ◽  
pp. 1642-1651 ◽  
Author(s):  
M J Weiss ◽  
C Yu ◽  
S H Orkin
Keyword(s):  
Transcription Factor ◽  
Cell Line ◽  
Zinc Finger ◽  
Es Cells ◽  
Embryonic Stem ◽  
Erythroid Cell ◽  
Transactivation Domain ◽  
Stage Of Development ◽  
Erythroid Maturation

The zinc finger transcription factor GATA-1 is essential for erythropoiesis. In its absence, committed erythroid precursors arrest at the proerythroblast stage of development and undergo apoptosis. To study the function of GATA-1 in an erythroid cell environment, we generated an erythroid cell line from in vitro-differentiated GATA-1- murine embryonic stem (ES) cells. These cells, termed G1E for GATA-1- erythroid, proliferate as immature erythroblasts yet complete differentiation upon restoration of GATA-1 function. We used rescue of terminal erythroid maturation in G1E cells as a stringent cellular assay system in which to evaluate the functional relevance of domains of GATA-1 previously characterized in nonhematopoietic cells. At least two major differences were established between domains required in G1E cells and those required in nonhematopoietic cells. First, an obligatory transactivation domain defined in conventional nonhematopoietic cell transfection assays is dispensable for terminal erythroid maturation. Second, the amino (N) zinc finger, which is nonessential for binding to the vast majority of GATA DNA motifs, is strictly required for GATA-1-mediated erythroid differentiation. Our data lead us to propose a model in which a nuclear cofactor(s) interacting with the N-finger facilitates transcriptional action by GATA-1 in erythroid cells. More generally, our experimental approach highlights critical differences in the action of cell-specific transcription proteins in different cellular environments and the power of cell lines derived from genetically modified ES cells to elucidate gene function.

Activating transcription factor 2 increases transactivation and protein stability of hypoxia-inducible factor 1α in hepatocytes

2009 ◽  
Vol 424 (2) ◽  
pp. 285-296 ◽  
Author(s):  
Jeong Hae Choi ◽  
Hyun Kook Cho ◽  
Yung Hyun Choi ◽  
JaeHun Cheong
Keyword(s):  
Transcription Factor ◽  
Protein Stability ◽  
Gene Transcription ◽  
Hypoxia Inducible Factor ◽  
Protein Stabilization ◽  
Hypoxic Conditions ◽  
Tumour Suppressor Protein ◽  
Activating Transcription Factor

HIF-1 (hypoxia inducible factor 1) performs a crucial role in mediating the response to hypoxia. However, other transcription factors are also capable of regulating hypoxia-induced target-gene transcription. In a previous report, we demonstrated that the transcription factor ATF-2 (activating transcription factor 2) regulates hypoxia-induced gene transcription, along with HIF-1α. In the present study, we show that the protein stability of ATF-2 is induced by hypoxia and the hypoxia-mimic CoCl2 (cobalt chloride), and that ATF-2 induction enhances HIF-1α protein stability via direct protein interaction. The knockdown of ATF-2 using small interfering RNA and translation-inhibition experiments demonstrated that ATF-2 plays a key role in the maintenance of the expression level and transcriptional activity of HIF-1α. Furthermore, we determined that ATF-2 interacts directly with HIF-1α both in vivo and in vitro and competes with the tumour suppressor protein p53 for HIF-1α binding. Collectively, these results show that protein stabilization of ATF-2 under hypoxic conditions is required for the induction of the protein stability and transactivation activity of HIF-1α for efficient hypoxia-associated gene expression.

GA Binding Protein (GABP) Is Required for Development and Maturation of Myeloid Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 776-776
Author(s):  
Zhongfa Yang ◽  
Alan G. Rosmarin
Keyword(s):  
Cell Cycle ◽  
Transcription Factor ◽  
Target Genes ◽  
Embryonic Stem ◽  
Myeloid Cells ◽  
Transactivation Domain ◽  
Wild Type ◽  
Floxed Allele

Abstract GABP is an ets transcription factor that regulates transcription of key myeloid genes, including CD18 (beta2 leukocyte integrin), neutrophil elastase, lysozyme, and other key mediators of the inflammatory response; it is also known to regulate important cell cycle control genes. GABP consists of two distinct and unrelated proteins that, together, form a functional transcription factor complex. GABPalpha (GABPa) is an ets protein that binds to DNA; it forms a tetrameric complex by recruiting its partner, GABPbeta (GABPb), which contains the transactivation domain. GABPa is a single copy gene in both the human and murine genomes and it is the only protein that can recruit GABPb to DNA. We cloned GABPa from a murine genomic BAC library and prepared a targeting vector in which exon 9 (which encodes the GABPa ets domain) was flanked by loxP (floxed) recombination sites. The targeting construct was electroporated into embryonic stem cells, homologous recombinants were implanted into pseudopregnant mice, heterozygous floxed GABPa mice were identified, and intercrossing yielded expected Mendelian ratios of wild type, heterozygous, and homozygous floxed GABPa mice. Breeding of heterozygous floxed GABPa mice to CMV-Cre mice (which express Cre recombinase in all tissues) yielded expected numbers of hemizygous mice (only one intact GABPa allele), but no nullizygous (GABPa−/−) mice among 64 pups; we conclude that homozygous deletion of GABPa causes an embryonic lethal defect. To determine the effect of GABPa deletion on myeloid cell development, we bred heterozygous and homozygous floxed mice to LysMCre mice, which express Cre only in myeloid cells. These mice had a normal complement of myeloid cells but, unexpectedly, PCR indicated that their Gr1+ myeloid cells retained an intact (undeleted) floxed GABPa allele. We detected similar numbers of in vitro myeloid colonies from bone marrow of wild type, heterozygous floxed, and homozygous floxed progeny of LysMCre matings. However, PCR of twenty individual in vitro colonies from homozygous floxed mice indicated that they all retained an intact floxed allele. Breeding of floxed GABPa/LysMCre mice with hemizygous mice indicated that retention of a floxed allele was not due to incomplete deletion by LysMCre; rather, it appears that only myeloid cells that retain an intact GABPa allele can survive to mature in vitro or in vivo. We prepared murine embryonic fibroblasts from homozygous floxed mice and efficiently deleted GABPa in vitro. We found striking abnormalities in proliferation and G1/S phase arrest. We used quantitative RT-PCR to identify mechanisms that account for the altered growth of GABPa null cells. We found dramatically reduced expression of known GABP target genes that regulate DNA synthesis and cell cycle that appear to account for the proliferative defect. We conclude that GABPa is required for growth and maturation of myeloid cells and we identified downstream targets that may account for their failure to proliferate and mature in vitro and in vivo.

scholarly journals Activating transcription factor-2 (ATF2) is a key determinant of resistance to endocrine treatment in an in vitro model of breast cancer

2020 ◽  
Vol 22 (1) ◽  
Author(s):  
Athina Giannoudis ◽  
Mohammed Imad Malki ◽  
Bharath Rudraraju ◽  
Hisham Mohhamed ◽  
Suraj Menon ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Gene Expression ◽  
Transcription Factor ◽  
Endocrine Resistance ◽  
Endocrine Treatment ◽  
Mcf7 Cells ◽  
Microarray Gene Expression ◽  
Mcf7 Cell Line ◽  
Activating Transcription Factor

Abstract Background Activating transcription factor-2 (ATF2), a member of the leucine zipper family of DNA binding proteins, has been implicated as a tumour suppressor in breast cancer. However, its exact role in breast cancer endocrine resistance is still unclear. We have previously shown that silencing of ATF2 leads to a loss in the growth-inhibitory effects of tamoxifen in the oestrogen receptor (ER)-positive, tamoxifen-sensitive MCF7 cell line and highlighted that this multi-faceted transcription factor is key to the effects of tamoxifen in an endocrine sensitive model. In this work, we explored further the in vitro role of ATF2 in defining the resistance to endocrine treatment. Materials and methods We knocked down ATF2 in TAMR, LCC2 and LCC9 tamoxifen-resistant breast cancer cell lines as well as the parental tamoxifen sensitive MCF7 cell line and investigated the effects on growth, colony formation and cell migration. We also performed a microarray gene expression profiling (Illumina Human HT12_v4) to explore alterations in gene expression between MCF7 and TAMRs after ATF2 silencing and confirmed gene expression changes by quantitative RT-PCR. Results By silencing ATF2, we observed a significant growth reduction of TAMR, LCC2 and LCC9 with no such effect observed with the parental MCF7 cells. ATF2 silencing was also associated with a significant inhibition of TAMR, LCC2 and LCC9 cell migration and colony formation. Interestingly, knockdown of ATF2 enhanced the levels of ER and ER-regulated genes, TFF1, GREB1, NCOA3 and PGR, in TAMR cells both at RNA and protein levels. Microarray gene expression identified a number of genes known to mediate tamoxifen resistance, to be differentially regulated by ATF2 in TAMR in relation to the parental MCF7 cells. Moreover, differential pathway analysis confirmed enhanced ER activity after ATF2 knockdown in TAMR cells. Conclusion These data demonstrate that ATF2 silencing may overcome endocrine resistance and highlights further the dual role of this transcription factor that can mediate endocrine sensitivity and resistance by modulating ER expression and activity.

scholarly journals Suppression of CHOP Reduces Neuronal Apoptosis and Rescues Cognitive Impairment Induced by Intermittent Hypoxia by Inhibiting Bax and Bak Activation

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Linhao Xu ◽  
Yanli Bi ◽  
Yizhou Xu ◽  
Yihao Wu ◽  
Xiaoxue Du ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Synaptic Plasticity ◽  
Signaling Pathway ◽  
Intermittent Hypoxia ◽  
Specific Chemical ◽  
Activating Transcription Factor ◽  
Induced Apoptosis

Our previous study showed that growth arrest- and DNA damage-inducible gene 153 (GAD153/CHOP) plays an important role in intermittent hypoxia- (IH-) induced apoptosis and impaired synaptic plasticity. This study is aimed at determining which signaling pathway is activated to induce CHOP and the role of this protein in mitochondria-dependent apoptosis induced by IH. In the in vivo study, mice were placed in IH chambers for 8 h daily over a period of 2 weeks; the IH chambers had oxygen (O2) concentrations that oscillated between 10% and 21%, cycling every 90 s. In the in vitro study, PC12 cells were exposed to 21% O2 (normoxia) or 8 IH cycles (25 min at 21% O2 and 35 min at 0.1% O2 for each cycle). After 2 weeks of IH treatment, we observed that the expression levels of phosphorylated protein kinase-like endoplasmic reticulum kinase (p-PERK), activating transcription factor 4 (ATF-4) and phosphorylated eukaryotic initiation factor 2 alpha (p-elf2α), were increased, but the levels of activating transcription factor 6 (ATF-6) and inositol-requiring enzyme 1 (IRE-1) were not increased. GSK2606414, a specific chemical inhibitor of the PERK pathway, reduced the expression of p-PERK, ATF-4, p-elf2α, and CHOP and rescued ER structure. In addition, Bax and Bak accumulated in the mitochondria after IH treatment, which induced cytochrome c release and initiated apoptosis. These effects were prevented by GSK2606414 and CHOP shRNA. Finally, the impaired long-term potentiation and long-term spatial memory in the IH group were rescued by GSK2606414. Together, the data from the in vitro and in vivo experiments indicate that IH-induced apoptosis and impaired synaptic plasticity were mediated by the PERK-ATF-4-CHOP pathway. Suppressing PERK-ATF-4-CHOP signaling pathway attenuated mitochondria-dependent apoptosis by reducing the expression of Bax and Bak in mitochondria, which may serve as novel adjunct therapeutic strategy for ameliorating obstructive sleep apnea- (OSA-) induced neurocognitive impairment.

scholarly journals Molecular mechanism of attenuation of heat shock transcription factor 1 activity

2019 ◽  
Author(s):  
Szymon W. Kmiecik ◽  
Laura Le Breton ◽  
Matthias P. Mayer
Keyword(s):  
Transcription Factor ◽  
Heat Shock ◽  
Leucine Zipper ◽  
Transcriptional Response ◽  
Heat Shock Transcription Factor ◽  
Transactivation Domain ◽  
Proteotoxic Stress ◽  
Transcription Factor 1 ◽  
Over 40 Years

AbstractThe heat shock response is a universal transcriptional response to proteotoxic stress orchestrated by heat shock transcription factor Hsf1 in all eukaryotic cells. Despite over 40 years of intense research, the mechanism of HSF1 activity regulation remains poorly understood at a molecular level. In metazoa Hsf1 trimerizes upon heat shock through a leucin-zipper domain and binds to DNA. How Hsf1 is dislodged from DNA and monomerized remained enigmatic. Here, we demonstrate that trimeric Hsf1 is dissociated from DNA in vitro by Hsc70 and DnaJB1. Hsc70 acts at two distinct sites on Hsf1. Hsf1 trimers are monomerized by successive cycles of entropic pulling, unzipping the triple leucine-zipper. This process directly monitors the concentration of Hsc70 and DnaJB1. During heat shock adaptation Hsc70 first binds to the transactivation domain leading to partial attenuation of the response and subsequently, at higher concentrations, Hsc70 removes Hsf1 from DNA to restore the resting state.

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