Requirement ofFoxD3-class signaling for neural crest determination inXenopus

Development ◽  
2001 ◽  
Vol 128 (13) ◽  
pp. 2525-2536 ◽  
Author(s):  
Noriaki Sasai ◽  
Kenji Mizuseki ◽  
Yoshiki Sasai
Keyword(s):  
Neural Crest ◽  
Dominant Negative ◽  
Related Factor ◽  
Embryonic Patterning ◽  
Loss Of Function ◽  
Upstream Regulator ◽  
Dominant Negative Form ◽  
Neural Crest Differentiation ◽  
Negative Form

Fox factors (winged-helix transcription factors) play important roles in early embryonic patterning. We show here that FoxD3 (Forkhead 6) regulates neural crest determination in Xenopus embryos. Expression of FoxD3 in the presumptive neural crest region starts at the late gastrula stage in a manner similar to that of Slug, and overlaps with that of Zic-r1. When overexpressed in the embryo and in ectodermal explants, FoxD3 induces expression of neural crest markers. Attenuation of FoxD3-related signaling by a dominant-negative FoxD3 construct (FoxD3delN) inhibits neural crest differentiation in vivo without suppressing the CNS marker Sox2. Interestingly, these loss-of-function phenotypes are reversed by coinjecting Slug. In animal cap explants, neural crest differentiation induced by Slug and Wnt3a is also inhibited by FoxD3delN but not by a dominant-negative form of XBF2. Loss-of-function studies using dominant-negative forms of FoxD3 and Slug indicate that Slug induction by Zic factors requires FoxD3-related signaling, and that FoxD3 and Slug have different requirements in inducing downstream neural crest markers. These data demonstrate that FoxD3 (or its closely related factor) is an essential upstream regulator of neural crest determination.

scholarly journals Functional Myc-Max heterodimer is required for activation-induced apoptosis in T cell hybridomas.

1994 ◽  
Vol 180 (6) ◽  
pp. 2413-2418 ◽  
Author(s):  
R P Bissonnette ◽  
A McGahon ◽  
A Mahboubi ◽  
D R Green
Keyword(s):  
T Cell ◽  
Apoptotic Cell ◽  
Tolerance Induction ◽  
Dominant Negative ◽  
Binding Partner ◽  
Dominant Negative Form ◽  
Dominant Negative Activity ◽  
Induced Apoptosis ◽  
Negative Form

T cell hybridomas respond to activation signals by undergoing apoptotic cell death, and this is likely to represent comparable events related to tolerance induction in immature and mature T cells in vivo. Previous studies using antisense oligonucleotides implicated the c-Myc protein in the phenomenon of activation-induced apoptosis. This role for c-Myc in apoptosis is now confirmed in studies using a dominant negative form of its heterodimeric binding partner, Max, which we show here inhibits activation-induced apoptosis. Further, coexpression of a reciprocally mutant Myc protein capable of forming functional heterodimers with the mutant Max can compensate for the dominant negative activity and restore activation-induced apoptosis. These results imply that Myc promotes activation-induced apoptosis by obligatory heterodimerization with Max, and therefore, by regulating gene transcription.

FGF suppresses apoptosis and induces differentiation of fibre cells in the mouse lens

Development ◽  
1995 ◽  
Vol 121 (12) ◽  
pp. 4383-4393 ◽  
Author(s):  
R.L. Chow ◽  
G.D. Roux ◽  
M. Roghani ◽  
M.A. Palmer ◽  
D.B. Rifkin ◽  
...  
Keyword(s):  
Growth Factor ◽  
Transgenic Mice ◽  
Dominant Negative ◽  
Fgf Receptor ◽  
Fibre Cell ◽  
Dominant Negative Form ◽  
Lens Fibre ◽  
Mouse Lens ◽  
Negative Form

To determine whether fibroblast growth factor (FGF) has a role in lens development, we have generated transgenic mice expressing a dominant-negative form of the murine FGF receptor-1 (FGFRDN) in the lens. Using the fibre cell-specific alpha A-crystallin promoter to express the FGFRDN, we have asked whether FGF is required for fibre cell differentiation. The transgenic mice display diminished differentiation of fibre cells as indicated by their reduced elongation. In addition, transgenic lenses have an unusual refractile anomaly that morphological and biochemical data show results from the apoptosis of fibre cells in the central region of the lens. These results show that lens fibre cells are dependent on FGF for their survival and differentiation, and demonstrate that growth factor deprivation in vivo can lead to apoptosis.

scholarly journals An EP overexpression screen for genetic modifiers of Notch pathway function in Drosophila melanogaster

2004 ◽  
Vol 83 (2) ◽  
pp. 71-82 ◽  
Author(s):  
LAUREN E. HALL ◽  
SHAUNA J. ALEXANDER ◽  
MICHAEL CHANG ◽  
NATHANIEL S. WOODLING ◽  
BARRY YEDVOBNICK
Keyword(s):  
Notch Signaling ◽  
Notch Pathway ◽  
Dominant Negative ◽  
Genetic Modifiers ◽  
Loss Of Function ◽  
Partial Loss ◽  
Dominant Negative Form ◽  
Nuclear Component ◽  
Pathway Function ◽  
Negative Form

The Notch pathway comprises a signal transduction cascade required for the proper formation of multiple tissues during metazoan development. Originally described in Drosophila for its role in nervous system formation, the pathway has attracted much wider interest owing to its fundamental roles in a range of developmental and disease-related processes. Despite extensive analysis, Notch signaling is not completely understood and it appears that additional components of the pathway remain to be identified and characterized. Here, we describe a novel genetic strategy to screen for additional Notch pathway genes. The strategy combines partial loss of function for pathway activity with Enhancer-promoter (EP)-induced overexpression of random loci across the dorsoventral wing margin. Mastermind (Mam) is a nuclear component of the Notch signaling cascade. Using a GAL4-UAS-driven dominant-negative form of Mam, we created a genotype that exhibits a completely penetrant dominant wing-nicking phenotype. This phenotype was assayed for enhancement or suppression after outcrossing to several thousand EP lines. The screen identified known components or modifiers of Notch pathway function, as well as several potential new components. Our results suggest that a genetic screen that combines partial loss of function with random gene overexpression might be a useful strategy in the analysis of developmental pathways.

scholarly journals Myocardial Expression of a Dominant-Negative Form of Daxx Decreases Infarct Size and Attenuates Apoptosis in an In Vivo Mouse Model of Ischemia/Reperfusion Injury

Circulation ◽  
2007 ◽  
Vol 116 (23) ◽  
pp. 2709-2717 ◽  
Author(s):  
François Roubille ◽  
Stéphane Combes ◽  
Juani Leal-Sanchez ◽  
Christian Barrère; ◽  
Frédéric Cransac ◽  
...  
Keyword(s):  
Mouse Model ◽  
Infarct Size ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Dominant Negative ◽  
Dominant Negative Form ◽  
Negative Form

scholarly journals Selection of a Dominant Negative Retinoblastoma Protein (RB) Inhibiting Satellite Myoblast Differentiation Implies an Indirect Interaction between MyoD and RB

2000 ◽  
Vol 20 (14) ◽  
pp. 5129-5139 ◽  
Author(s):  
Feng-Qian Li ◽  
Archie Coonrod ◽  
Marshall Horwitz
Keyword(s):  
Myogenic Differentiation ◽  
Retinoblastoma Protein ◽  
Dominant Negative ◽  
Myoblast Differentiation ◽  
Loss Of Function ◽  
Lysosomal Protease ◽  
Dominant Negative Form ◽  
Genes Encoding

ABSTRACT Satellite myoblasts serve as stem cells in postnatal skeletal muscle, but the genes responsible for choosing between growth versus differentiation are largely undefined. We have used a novel genetic approach to identify genes encoding proteins whose dominant negative inhibition is capable of interrupting the in vitro differentiation of C2C12 murine satellite myoblasts. The screen is based on fusion of a library of cDNA fragments with the lysosomal protease cathepsin B (CB), such that the fusion protein intracellularly diverts interacting factors to the lysosome. Among other gene fragments selected in this screen, including those of known and novel sequence, is the retinoblastoma protein (RB) pocket domain. This unique dominant negative form of RB allows us to genetically determine if MyoD and RB associate in vivo. The dominant negative CB-RB fusion produces a cellular phenotype indistinguishable from recessive loss of function RB mutations. The fact that the dominant negative RB inhibits myogenic differentiation in the presence of nonlimiting concentrations of either RB or MyoD suggests that these two proteins do not directly interact. We further show that the dominant negative RB inhibits E2F1 but cannot inhibit a forced E2F1-RB dimer. Therefore, E2F1 is a potential mediator of the dominant negative inhibition of MyoD by CB-RB during satellite cell differentiation. We propose this approach to be generally suited to the investigation of gene function, even when little is known about the pathway being studied.

scholarly journals Functional Verification of Novel ELMO1 Variants By Live Imaging in Zebrafish

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 3121-3121
Author(s):  
Rongtao Xue ◽  
Ying Wang ◽  
Tienan Wang ◽  
Mei Lyu ◽  
Guiling Mo ◽  
...  
Keyword(s):  
Cell Motility ◽  
Conflicts Of Interest ◽  
Live Imaging ◽  
Dominant Negative ◽  
Functional Verification ◽  
Transient Expression Assay ◽  
Dominant Negative Form ◽  
Reduced Mobility ◽  
Negative Form

Abstract ELMO1 (Engulfment and Cell Motility1) is a gene involved in regulating cell motility through the ELMO1-DOCK2-RAC complex. Contrary to DOCK2 (Dedicator of Cytokinesis 2) deficiency, which has been reported to be associated with immunodeficiency diseases, variants of ELMO1 have been associated with autoimmune diseases, such as diabetes and rheumatoid arthritis (RA). To explore the function of ELMO1 in immune cells and to verify the functions of novel ELMO1 variants in vivo, we established a zebrafish elmo1 mutant model. Live imaging revealed that similar to mammals, the motility of neutrophils and T-cells was largely attenuated in zebrafish mutants. Consequently, the response of neutrophils to injury or bacterial infection was significantly reduced in the mutants. Furthermore, the reduced mobility of neutrophils could be rescued by the expression of constitutively activated Rac proteins, suggesting that zebrafish elmo1 mutant functions via a conserved mechanism. With this mutant, three novel human ELMO1 variants were transiently and specifically expressed in zebrafish neutrophils. Two variants, p.E90K (c.268G>A) and p.D194G (c.581A>G) could efficiently recover the motility defect of neutrophils in the elmo1 mutant; however, the p.R354X (c.1060C>T) variant failed to rescue the mutant. Acts as a dominant-negative form, p.R354X (c.1060C>T) which failed to rescue the elmo1 mutant and inhibited neutrophil movement in siblings. Based on those results, we identified that zebrafish elmo1 played conserved roles in cell motility, similar to higher vertebrates. Using the transient-expression assay, zebrafish elmo1 mutants could serve as an effective model for human variant verification in vivo. Disclosures No relevant conflicts of interest to declare.

scholarly journals The Hippo effector TAZ cooperates with oncogenic β-catenin in experimental and human hepatoblastoma development

2019 ◽  
Author(s):  
Junyan Tao ◽  
Shu Zhang ◽  
Jie Zhang ◽  
Katja Evert ◽  
Xiaolei Li ◽  
...  
Keyword(s):  
Sleeping Beauty ◽  
Dominant Negative ◽  
Downstream Effector ◽  
Tail Vein Injection ◽  
Mesenchymal Differentiation ◽  
Dominant Negative Form ◽  
Transcription Factor 1 ◽  
Negative Form

Abstract Backgrounds: Hepatoblastoma (HB) is the most common pediatric liver tumor. Though Wnt/β-catenin and Hippo cascades are implicated in HB development, there is no study on the crosstalk of β-catenin and Hippo downstream effector TAZ in HB. Methods: The expression of TAZ and of β-catenin in human HB specimens was assessed by immunohistochemistry (IHC). The functional interplay between TAZ and β-catenin was tested through delivering either an activated form of TAZ (TAZS89A) alone or co-delivering TAZS89A and an activated form of β-catenin (∆N90-β-catenin) to mouse liver using sleeping beauty transposase via hydrodynamic tail vein injection (SBT-HTVI). In addition, the role of transcriptional enhanced associate domain (TEAD) factors, canonical Notch cascade, Yap, and the tumor modifier heat shock transcription factor 1 (HSF1) along TAZ/β-catenin-driven HB development was studied in vivo and vitro. Results: Activation of TAZ often co-occurred with that of β-catenin in clinical specimens. While overexpression of TAZS89A alone was unable to promote liver tumorigenesis, the concomitant overexpression of TAZ and ∆N90-β-catenin induced the development of HB lesions exhibiting both epithelial and mesenchymal features. Mechanistically, HB development driven by TAZ/β-catenin required TAZ interaction with TEAD factors. Furthermore, TAZ/β-catenin overexpression induced HB development in conditional Yes-associated protein knockout (Yap KO) mice, indicating that Yap activation is dispensable in this model. Activation of the Notch signaling was observed in TAZ/β-catenin mouse lesions, consistent with that reported in human HBs. Blocking of the canonical Notch cascade using the dominant negative form of RBP-J (dnRBP-J) did not inhibit TAZ/β-catenin dependent HB formation in mice, although suppressed the mesenchymal differentiation. Similarly, upregulation of HSF1 was detected in TAZ/β-catenin lesions, but its inactivation did not affect HB development. In human HB cell lines, silencing of TAZ resulted in decreased cell growth, which was reduced more substantially when TAZ knockdown was associated with suppression of either β-catenin or YAP gene. Conclusions: Overall, our study identifies TAZ as a critical oncogene in HB development and progression. Yap, Notch, and HSF1 are dispensable for TAZ/β-catenin induced HB development in mice.

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