The transcription factor Schnurri plays a dual role in mediating Dpp signaling during embryogenesis

Development ◽  
2001 ◽  
Vol 128 (9) ◽  
pp. 1657-1670 ◽  
Author(s):  
J. Torres-Vazquez ◽  
S. Park ◽  
R. Warrior ◽  
K. Arora
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Cell Fate ◽  
Target Genes ◽  
Gene Activation ◽  
Nuclear Accumulation ◽  
Embryonic Patterning ◽  
Specific Analysis ◽  
Positive Input ◽  
Affect Gene Expression

Decapentaplegic (Dpp), a homolog of vertebrate bone morphogenic protein 2/4, is crucial for embryonic patterning and cell fate specification in Drosophila. Dpp signaling triggers nuclear accumulation of the Smads Mad and Medea, which affect gene expression through two distinct mechanisms: direct activation of target genes and relief of repression by the nuclear protein Brinker (Brk). The zinc-finger transcription factor Schnurri (Shn) has been implicated as a co-factor for Mad, based on its DNA-binding ability and evidence of signaling dependent interactions between the two proteins. A key question is whether Shn contributes to both repression of brk as well as to activation of target genes. We find that during embryogenesis, brk expression is derepressed in shn mutants. However, while Mad is essential for Dpp-mediated repression of brk, the requirement for shn is stage specific. Analysis of brk; shn double mutants reveals that upregulation of brk does not account for all aspects of the shn mutant phenotype. Several Dpp target genes are expressed at intermediate levels in double mutant embryos, demonstrating that shn also provides a brk-independent positive input to gene activation. We find that Shn-mediated relief of brk repression establishes broad domains of gene activation, while the brk-independent input from Shn is crucial for defining the precise limits and levels of Dpp target gene expression in the embryo.

SUMOylated Non-canonical Polycomb PRC1.6 Complex as a Prerequisite for Recruitment of Transcription Factor RBPJ

2021 ◽  
Author(s):  
Małgorzata Sotomska ◽  
Robert Liefke ◽  
Francesca Ferrante ◽  
Heiko Schwederski ◽  
Franz Oswald ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Cell Fate ◽  
Target Gene ◽  
Target Genes ◽  
Adult Stem Cell ◽  
Notch Signalling ◽  
Cell Fate Decisions ◽  
Contact Points ◽  
Coactivator Complex

Abstract BackgroundNotch signaling controls cell fate decisions in many contexts during development and adult stem cell homeostasis and, when dysregulated, leads to carcinogenesis. The central transcription factor RBPJ assembles the Notch coactivator complex in the presence of Notch signalling, and represses Notch target gene expression in its absence.ResultsWe identified L3MBTL2 and additional members of the non-canonical polycomb repressive PRC1.6 complex in DNA-bound RBPJ associated complexes and demonstrate that L3MBTL2 directly interacts with RBPJ. Depletion of RBPJ does not affect occupancy of PRC1.6 components at Notch target genes. Conversely, absence of L3MBTL2 reduces RBPJ occupancy at enhancers of Notch target genes. Since L3MBTL2 and additional members of the PRC1.6 are known to be SUMOylated, we investigated whether RBPJ uses SUMO-moieties as contact points. Indeed, we found that RBPJ binds to SUMO2/3 and that this interaction depends on a defined SUMO-interaction motif. Furthermore, we show that pharmacological inhibition of SUMOylation reduces RBPJ occupancy at Notch target genes.ConclusionsWe propose that the PRC1.6 complex and its conjugated SUMO-modifications provide a scaffold that is recognized by RBPJ and promotes its recruitment to Notch target genes.

scholarly journals SUMOylated non-canonical polycomb PRC1.6 complex as a prerequisite for recruitment of transcription factor RBPJ

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Małgorzata Sotomska ◽  
Robert Liefke ◽  
Francesca Ferrante ◽  
Heiko Schwederski ◽  
Franz Oswald ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Notch Signaling ◽  
Cell Fate ◽  
Target Gene ◽  
Target Genes ◽  
Adult Stem Cell ◽  
Cell Fate Decisions ◽  
Contact Points ◽  
Coactivator Complex

Abstract Background Notch signaling controls cell fate decisions in many contexts during development and adult stem cell homeostasis and, when dysregulated, leads to carcinogenesis. The central transcription factor RBPJ assembles the Notch coactivator complex in the presence of Notch signaling, and represses Notch target gene expression in its absence. Results We identified L3MBTL2 and additional members of the non-canonical polycomb repressive PRC1.6 complex in DNA-bound RBPJ associated complexes and demonstrate that L3MBTL2 directly interacts with RBPJ. Depletion of RBPJ does not affect occupancy of PRC1.6 components at Notch target genes. Conversely, absence of L3MBTL2 reduces RBPJ occupancy at enhancers of Notch target genes. Since L3MBTL2 and additional members of the PRC1.6 are known to be SUMOylated, we investigated whether RBPJ uses SUMO-moieties as contact points. Indeed, we found that RBPJ binds to SUMO2/3 and that this interaction depends on a defined SUMO-interaction motif. Furthermore, we show that pharmacological inhibition of SUMOylation reduces RBPJ occupancy at Notch target genes. Conclusions We propose that the PRC1.6 complex and its conjugated SUMO-modifications provide a favorable environment for binding of RBPJ to Notch target genes.

scholarly journals Mechanisms Underlying the Delayed Activation of the Cap1 Transcription Factor in Candida albicans following Combinatorial Oxidative and Cationic Stress Important for Phagocytic Potency

mBio ◽  
2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Iaroslava Kos ◽  
Miranda J. Patterson ◽  
Sadri Znaidi ◽  
Despoina Kaloriti ◽  
Alessandra da Silva Dantas ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Candida Albicans ◽  
Stress Responses ◽  
Nuclear Export ◽  
Fungal Pathogens ◽  
Target Genes ◽  
Nacl Stress ◽  
Nuclear Accumulation ◽  
Simultaneous Exposure

ABSTRACT Following phagocytosis, microbes are exposed to an array of antimicrobial weapons that include reactive oxygen species (ROS) and cationic fluxes. This is significant as combinations of oxidative and cationic stresses are much more potent than the corresponding single stresses, triggering the synergistic killing of the fungal pathogen Candida albicans by “stress pathway interference.” Previously we demonstrated that combinatorial oxidative plus cationic stress triggers a dramatic increase in intracellular ROS levels compared to oxidative stress alone. Here we show that activation of Cap1, the major regulator of antioxidant gene expression in C. albicans , is significantly delayed in response to combinatorial stress treatments and to high levels of H 2 O 2 . Cap1 is normally oxidized in response to H 2 O 2 ; this masks the nuclear export sequence, resulting in the rapid nuclear accumulation of Cap1 and the induction of Cap1-dependent genes. Here we demonstrate that following exposure of cells to combinatorial stress or to high levels of H 2 O 2 , Cap1 becomes trapped in a partially oxidized form, Cap1 OX-1 . Notably, Cap1-dependent gene expression is not induced when Cap1 is in this partially oxidized form. However, while Cap1 OX-1 readily accumulates in the nucleus and binds to target genes following high-H 2 O 2 stress, the nuclear accumulation of Cap1 OX-1 following combinatorial H 2 O 2 and NaCl stress is delayed due to a cationic stress-enhanced interaction with the Crm1 nuclear export factor. These findings define novel mechanisms that delay activation of the Cap1 transcription factor, thus preventing the rapid activation of the stress responses vital for the survival of C. albicans within the host. IMPORTANCE Combinatorial stress-mediated synergistic killing represents a new unchartered area in the field of stress signaling. This phenomenon contrasts starkly with “stress cross-protection,” where exposure to one stress protects against subsequent exposure to a different stress. Previously we demonstrated that the pathogen Candida albicans is acutely sensitive to combinations of cationic and oxidative stresses, because the induction of H 2 O 2 -responsive genes is blocked in the presence of cationic stress. We reveal that this is due to novel mechanisms that delay activation of the Cap1 AP-1-like transcription factor, the major regulator of the H 2 O 2 -induced regulon. Cap1 becomes trapped in a partially oxidized form following simultaneous exposure to oxidative and cationic stresses. In addition, cationic stress promotes the interaction of Cap1 with the Crm1 nuclear export factor, thus inhibiting its nuclear accumulation. These mechanisms probably explain the potency of neutrophils, which employ multiple stresses to kill fungal pathogens.

scholarly journals Growth Hormone Upregulates Melanocyte-Inducing Transcription Factor Expression and Activity via JAK2-STAT5 and SRC Signaling in GH Receptor-Positive Human Melanoma

Cancers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1352 ◽  
Author(s):  
Reetobrata Basu ◽  
Prateek Kulkarni ◽  
Yanrong Qian ◽  
Christopher Walsh ◽  
Pranay Arora ◽  
...  
Keyword(s):  
Gene Expression ◽  
Growth Hormone ◽  
Transcription Factor ◽  
Cell Fate ◽  
Abc Transporters ◽  
Target Genes ◽  
Human Melanoma ◽  
Mesenchymal Transition ◽  
Expression And Activity

Growth hormone (GH) facilitates therapy resistance in the cancers of breast, colon, endometrium, and melanoma. The GH-stimulated pathways responsible for this resistance were identified as suppression of apoptosis, induction of epithelial-to-mesenchymal transition (EMT), and upregulated drug efflux by increased expression of ATP-binding cassette containing multidrug efflux pumps (ABC-transporters). In extremely drug-resistant melanoma, ABC-transporters have also been reported to mediate drug sequestration in intracellular melanosomes, thereby reducing drug efficacy. Melanocyte-inducing transcription factor (MITF) is the master regulator of melanocyte and melanoma cell fate as well as the melanosomal machinery. MITF targets such as the oncogene MET, as well as MITF-mediated processes such as resistance to radiation therapy, are both known to be upregulated by GH. Therefore, we chose to query the direct effects of GH on MITF expression and activity towards conferring chemoresistance in melanoma. Here, we demonstrate that GH significantly upregulates MITF as well as the MITF target genes following treatment with multiple anticancer drug treatments such as chemotherapy, BRAF-inhibitors, as well as tyrosine-kinase inhibitors. GH action also upregulated MITF-regulated processes such as melanogenesis and tyrosinase activity. Significant elevation in MITF and MITF target gene expression was also observed in mouse B16F10 melanoma cells and xenografts in bovine GH transgenic (bGH) mice compared to wild-type littermates. Through pathway inhibitor analysis we identified that both the JAK2-STAT5 and SRC activities were critical for the observed effects. Additionally, a retrospective analysis of gene expression data from GTEx, NCI60, CCLE, and TCGA databases corroborated our observed correlation of MITF function and GH action. Therefore, we present in vitro, in vivo, and in silico evidence which strongly implicates the GH–GHR axis in inducing chemoresistance in human melanoma by driving MITF-regulated and ABC-transporter-mediated drug clearance pathways.

scholarly journals Linking metabolic dysfunction with cardiovascular diseases: Brn-3b/POU4F2 transcription factor in cardiometabolic tissues in health and disease

2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Vishwanie S. Budhram-Mahadeo ◽  
Matthew R. Solomons ◽  
Eeshan A. O. Mahadeo-Heads
Keyword(s):  
Transcription Factor ◽  
Cardiovascular Diseases ◽  
Cell Fate ◽  
Target Genes ◽  
Cardiovascular Responses ◽  
Normal Function ◽  
Valuable Insight ◽  
Metabolic Dysfunction ◽  
Pathological Changes ◽  
Cardiac Responses

AbstractMetabolic and cardiovascular diseases are highly prevalent and chronic conditions that are closely linked by complex molecular and pathological changes. Such adverse effects often arise from changes in the expression of genes that control essential cellular functions, but the factors that drive such effects are not fully understood. Since tissue-specific transcription factors control the expression of multiple genes, which affect cell fate under different conditions, then identifying such regulators can provide valuable insight into the molecular basis of such diseases. This review explores emerging evidence that supports novel and important roles for the POU4F2/Brn-3b transcription factor (TF) in controlling cellular genes that regulate cardiometabolic function. Brn-3b is expressed in insulin-responsive metabolic tissues (e.g. skeletal muscle and adipose tissue) and is important for normal function because constitutive Brn-3b-knockout (KO) mice develop profound metabolic dysfunction (hyperglycaemia; insulin resistance). Brn-3b is highly expressed in the developing hearts, with lower levels in adult hearts. However, Brn-3b is re-expressed in adult cardiomyocytes following haemodynamic stress or injury and is necessary for adaptive cardiac responses, particularly in male hearts, because male Brn-3b KO mice develop adverse remodelling and reduced cardiac function. As a TF, Brn-3b regulates the expression of multiple target genes, including GLUT4, GSK3β, sonic hedgehog (SHH), cyclin D1 and CDK4, which have known functions in controlling metabolic processes but also participate in cardiac responses to stress or injury. Therefore, loss of Brn-3b and the resultant alterations in the expression of such genes could potentially provide the link between metabolic dysfunctions with adverse cardiovascular responses, which is seen in Brn-3b KO mutants. Since the loss of Brn-3b is associated with obesity, type II diabetes (T2DM) and altered cardiac responses to stress, this regulator may provide a new and important link for understanding how pathological changes arise in such endemic diseases.

scholarly journals Low-affinity transcription factor binding sites shape morphogen responses and enhancer evolution

2013 ◽  
Vol 368 (1632) ◽  
pp. 20130018 ◽  
Author(s):  
Andrea I. Ramos ◽  
Scott Barolo
Keyword(s):  
Transcription Factor ◽  
Binding Affinity ◽  
Binding Sites ◽  
Target Genes ◽  
Gene Activation ◽  
Transcriptional Response ◽  
Morphogen Gradients ◽  
Weak Binding ◽  
Initial Hypothesis

In the era of functional genomics, the role of transcription factor (TF)–DNA binding affinity is of increasing interest: for example, it has recently been proposed that low-affinity genomic binding events, though frequent, are functionally irrelevant. Here, we investigate the role of binding site affinity in the transcriptional interpretation of Hedgehog (Hh) morphogen gradients . We noted that enhancers of several Hh-responsive Drosophila genes have low predicted affinity for Ci, the Gli family TF that transduces Hh signalling in the fly. Contrary to our initial hypothesis, improving the affinity of Ci/Gli sites in enhancers of dpp , wingless and stripe , by transplanting optimal sites from the patched gene, did not result in ectopic responses to Hh signalling. Instead, we found that these enhancers require low-affinity binding sites for normal activation in regions of relatively low signalling. When Ci/Gli sites in these enhancers were altered to improve their binding affinity, we observed patterning defects in the transcriptional response that are consistent with a switch from Ci-mediated activation to Ci-mediated repression. Synthetic transgenic reporters containing isolated Ci/Gli sites confirmed this finding in imaginal discs. We propose that the requirement for gene activation by Ci in the regions of low-to-moderate Hh signalling results in evolutionary pressure favouring weak binding sites in enhancers of certain Hh target genes.

scholarly journals Functional effects of variation in transcription factor binding highlight long-range gene regulation by epromoters

2019 ◽  
Author(s):  
Joanna Mitchelmore ◽  
Nastasiya Grinberg ◽  
Chris Wallace ◽  
Mikhail Spivakov
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Statistical Power ◽  
Target Genes ◽  
Allelic Variation ◽  
Regulatory Function ◽  
Regulatory Sequences ◽  
Distal Enhancer ◽  
Association Testing ◽  
Gene Regulatory

AbstractIdentifying DNA cis-regulatory modules (CRMs) that control the expression of specific genes is crucial for deciphering the logic of transcriptional control. Natural genetic variation can point to the possible gene regulatory function of specific sequences through their allelic associations with gene expression. However, comprehensive identification of causal regulatory sequences in brute-force association testing without incorporating prior knowledge is challenging due to limited statistical power and effects of linkage disequilibrium. Sequence variants affecting transcription factor (TF) binding at CRMs have a strong potential to influence gene regulatory function, which provides a motivation for prioritising such variants in association testing. Here, we generate an atlas of CRMs showing predicted allelic variation in TF binding affinity in human lymphoblastoid cell lines (LCLs) and test their association with the expression of their putative target genes inferred from Promoter Capture Hi-C and immediate linear proximity. We reveal over 1300 CRM TF-binding variants associated with target gene expression, the majority of them undetected with standard association testing. A large proportion of CRMs showing associations with the expression of genes they contact in 3D localise to the promoter regions of other genes, supporting the notion of ‘epromoters’: dual-action CRMs with promoter and distal enhancer activity.

scholarly journals Strigolactone GR24 upregulates Nrf2 target genes and may protect against oxidative stress in skeletal muscle

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 1459
Author(s):  
Shalem Raju Modi ◽  
Tarja Kokkola
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Skeletal Muscle ◽  
Transcription Factor ◽  
Stress Responses ◽  
Mycorrhizal Fungi ◽  
Target Genes ◽  
Redox Homeostasis ◽  
Antioxidant Defences ◽  
Microarray Gene Expression

GR24 is a synthetic strigolactone analog, demonstrated to regulate the development of plants and arbuscular mycorrhizal fungi. GR24 possesses anti-cancer and anti-apoptotic properties, enhances insulin sensitivity and mitochondrial biogenesis in skeletal myotubes, inhibits adipogenesis, decreases inflammation in adipocytes and macrophages and downregulates the expression of hepatic gluconeogenic enzymes. Transcription factor Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) is a master regulator of antioxidant response, regulating a multitude of genes involved in cellular stress responses and anti-inflammatory pathways, thus maintaining cellular redox homeostasis. Nrf2 activation reduces the deleterious effects of mitochondrial toxins and has multiple roles in promoting mitochondrial function and dynamics. We studied the role of GR24 on gene expression in rat L6 skeletal muscle cells which were differentiated into myotubes. The myotubes were treated with GR24 and analyzed by microarray gene expression profiling. GR24 upregulated the cytoprotective transcription factor Nrf2 and its target genes, activating antioxidant defences, suggesting that GR24 may protect skeletal muscle from the toxic effects of oxidative stress.

scholarly journals Maximal STAT5-Induced Proliferation and Self-Renewal at Intermediate STAT5 Activity Levels

2008 ◽  
Vol 28 (21) ◽  
pp. 6668-6680 ◽  
Author(s):  
Albertus T. J. Wierenga ◽  
Edo Vellenga ◽  
Jan Jacob Schuringa
Keyword(s):  
Gene Expression ◽  
Cell Fate ◽  
Target Genes ◽  
Expression Patterns ◽  
Activity Levels ◽  
Dependent Manner ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Cell Fate Decisions

ABSTRACT The level of transcription factor activity critically regulates cell fate decisions, such as hematopoietic stem cell (HSC) self-renewal and differentiation. We introduced STAT5A transcriptional activity into human HSCs/progenitor cells in a dose-dependent manner by overexpression of a tamoxifen-inducible STAT5A(1*6)-estrogen receptor fusion protein. Induction of STAT5A activity in CD34+ cells resulted in impaired myelopoiesis and induction of erythropoiesis, which was most pronounced at the highest STAT5A transactivation levels. In contrast, intermediate STAT5A activity levels resulted in the most pronounced proliferative advantage of CD34+ cells. This coincided with increased cobblestone area-forming cell and long-term-culture-initiating cell frequencies, which were predominantly elevated at intermediate STAT5A activity levels but not at high STAT5A levels. Self-renewal of progenitors was addressed by serial replating of CFU, and only progenitors containing intermediate STAT5A activity levels contained self-renewal capacity. By extensive gene expression profiling we could identify gene expression patterns of STAT5 target genes that predominantly associated with a self-renewal and long-term expansion phenotype versus those that identified a predominant differentiation phenotype.

TCF: Lady Justice Casting the Final Verdict on the Outcome of Wnt Signalling

2002 ◽  
Vol 383 (2) ◽  
pp. 255-261 ◽  
Author(s):  
H. Brantjes ◽  
N. Barker ◽  
J. van Es ◽  
H. Clevers
Keyword(s):  
Cell Fate ◽  
Target Genes ◽  
Signal Transduction Pathway ◽  
Wnt Signalling ◽  
Early Event ◽  
Embryonic Patterning ◽  
Repressor Proteins ◽  
Downstream Effectors ◽  
Signalling Cascade

Abstract The Wnt signalling cascade plays an important role during embryonic patterning and cell fate determination and is highly conserved throughout evolution. Factors of the TCF/LEF HMG domain family (Tcfs) are the downstream effectors of this signal transduction pathway. Upon Wnt signalling, a cascade is initiated that results in the translocation of βcatenin to the nucleus, where it interacts with Tcf to generate a transcriptionally active complex. This bipartite transcription factor is targeted to the upstream regulatory regions of Tcf target genes. In the absence of Wnt signals, βcatenin is degraded in the cytoplasm via the ubiquitinproteasome pathway. Several proteins are instrumental in achieving this tight regulation of βcatenin levels in the cell, including adenomatous polyposis coli (APC), GSK3 β, and Axin/Conductin. Deregulation of the Wnt signalling pathway is implicated in several forms of cancer, such as colon carcinoma and melanoma. This deregulation is achieved via mutation of APC, βcatenin or Axin, resulting in elevated βcatenin levels and the presence of constitutively active Tcfβcatenin complexes in the nucleus. The accompanying inappropriate activation of target genes is considered to be a critical, early event in this carcinogenesis. In addition to regulating βcatenin levels, normal healthy cells have evolved a second level of regulation, by manipulating the activity of the Tcf proteins themselves. In the absence of Wnt signalling, Tcf complexes with several transcriptional repressor proteins ensuring active repression of Tcf target genes. In this review the dual role of Tcf proteins in the Wnt signalling cascade will be discussed.

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