Maternally controlled (beta)-catenin-mediated signaling is required for organizer formation in the zebrafish

Development ◽  
2000 ◽  
Vol 127 (18) ◽  
pp. 3899-3911 ◽  
Author(s):  
C. Kelly ◽  
A.J. Chin ◽  
J.L. Leatherman ◽  
D.J. Kozlowski ◽  
E.S. Weinberg
Keyword(s):  
Early Development ◽  
Nuclear Localization ◽  
Maternal Effect ◽  
Wnt Pathway ◽  
Gene Activity ◽  
Nuclear Accumulation ◽  
Beta Catenin ◽  
Yolk Syncytial Layer ◽  
Embryonic Shield ◽  
Maternal Gene

We have identified and characterized a zebrafish recessive maternal effect mutant, ichabod, that results in severe anterior and dorsal defects during early development. The ichabod mutation is almost completely penetrant, but exhibits variable expressivity. All mutant embryos fail to form a normal embryonic shield; most fail to form a head and notochord and have excessive development of ventral tail fin tissue and blood. Abnormal dorsal patterning can first be observed at 3.5 hpf by the lack of nuclear accumulation of (beta)-catenin in the dorsal yolk syncytial layer, which also fails to express bozozok/dharma/nieuwkoid and znr2/ndr1/squint. At the onset of gastrulation, deficiencies in expression of dorsal markers and expansion of expression of markers of ventral tissues indicate a dramatic alteration of dorsoventral identity. Injection of (beta)-catenin RNA markedly dorsalized ichabod embryos and often completely rescued the phenotype, but no measurable dorsalization was obtained with RNAs encoding upstream Wnt pathway components. In contrast, dorsalization was obtained when RNAs encoding either Bozozok/Dharma/Nieuwkoid or Znr2/Ndr1/Squint were injected. Moreover, injection of (beta)-catenin RNA into ichabod embryos resulted in activation of expression of these two genes, which could also activate each other. RNA injection experiments strongly suggest that the component affected by the ichabod mutation acts on a step affecting (beta)-catenin nuclear localization that is independent of regulation of (beta)-catenin stability. This work demonstrates that a maternal gene controlling localization of (beta)-catenin in dorsal nuclei is necessary for dorsal yolk syncytial layer gene activity and formation of the organizer in the zebrafish.

The protein product of the zebrafish homologue of the mouse T gene is expressed in nuclei of the germ ring and the notochord of the early embryo

Development ◽  
1992 ◽  
Vol 116 (4) ◽  
pp. 1021-1032 ◽  
Author(s):  
S. Schulte-Merker ◽  
R.K. Ho ◽  
B.G. Herrmann ◽  
C. Nusslein-Volhard
Keyword(s):  
Early Development ◽  
Nuclear Localization ◽  
Protein Product ◽  
Early Embryo ◽  
Paraxial Mesoderm ◽  
Zebrafish Embryos ◽  
Brachydanio Rerio ◽  
Cloning And Sequencing ◽  
Yolk Syncytial Layer ◽  
In Cells

Embryos mutant for the T gene, in mice, make insufficient mesoderm and fail to develop a notochord. We report the cloning and sequencing of the T gene in the zebrafish (Brachydanio rerio) and show the nuclear localization of the protein product. Both RNA and protein are found in cells of the germ ring, including enveloping layer cells, prior to and during gastrulation of zebrafish embryos. Nuclei of the yolk syncytial layer do not express Zf-T. High levels of expression are maintained throughout early development in the notochord, while in paraxial mesoderm cells the gene is turned off during gastrulation. Exposure of animal cap cells to activinA induces Zf-T expression, as does transplantation into the germ ring.

scholarly journals Ebolavirus VP24 Binding to Karyopherins Is Required for Inhibition of Interferon Signaling

2009 ◽  
Vol 84 (2) ◽  
pp. 1169-1175 ◽  
Author(s):  
Mathieu Mateo ◽  
St. Patrick Reid ◽  
Lawrence W. Leung ◽  
Christopher F. Basler ◽  
Viktor E. Volchkov
Keyword(s):  
Nuclear Localization ◽  
Nuclear Localization Signal ◽  
Nuclear Accumulation ◽  
Interferon Signaling ◽  
Loss Of Function ◽  
Proposed Model ◽  
Localization Signal ◽  
Ifn Γ ◽  
Alpha Beta ◽  
Signal Receptors

ABSTRACT The Ebolavirus VP24 protein counteracts alpha/beta interferon (IFN-α/β) and IFN-γ signaling by blocking the nuclear accumulation of tyrosine-phosphorylated STAT1 (PY-STAT1). According to the proposed model, VP24 binding to members of the NPI-1 subfamily of karyopherin alpha (KPNα) nuclear localization signal receptors prevents their binding to PY-STAT1, thereby preventing PY-STAT1 nuclear accumulation. This study now identifies two domains of VP24 required for inhibition of IFN-β-induced gene expression and PY-STAT1 nuclear accumulation. We demonstrate that loss of function correlates with loss of binding to KPNα proteins. Thus, the VP24 IFN antagonist function requires the ability of VP24 to interact with KPNα.

scholarly journals Live-Cell Fluorescence Imaging Reveals the Dynamics of Protein Kinase CK2 Individual Subunits

2003 ◽  
Vol 23 (3) ◽  
pp. 975-987 ◽  
Author(s):  
Odile Filhol ◽  
Arsenio Nueda ◽  
Véronique Martel ◽  
Delphine Gerber-Scokaert ◽  
Maria José Benitez ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Nuclear Localization ◽  
Protein Kinase Ck2 ◽  
Fluorescent Protein ◽  
Nuclear Translocation ◽  
Nuclear Accumulation ◽  
Nucleocytoplasmic Trafficking ◽  
Green Fluorescent ◽  
Nucleocytoplasmic Distribution ◽  
Kinase Ck2

ABSTRACT Protein kinase CK2 is a multifunctional enzyme which has long been described as a stable heterotetrameric complex resulting from the association of two catalytic (α or α′) and two regulatory (β) subunits. To track the spatiotemporal dynamics of CK2 in living cells, we fused its catalytic α and regulatory β subunits with green fluorescent protein (GFP). Both CK2 subunits contain nuclear localization domains that target them independently to the nucleus. Imaging of stable cell lines expressing low levels of GFP-CK2α or GFP-CK2β revealed the existence of CK2 subunit subpopulations exhibiting differential dynamics. Once in the nucleus, they diffuse randomly at different rates. Unlike CK2β, CK2α can shuttle, showing the dynamic nature of the nucleocytoplasmic trafficking of the kinase. When microinjected in the cytoplasm, the isolated CK2 subunits are rapidly translocated into the nucleus, whereas the holoenzyme complex remains in this cell compartment, suggesting an intramolecular masking of the nuclear localization sequences that suppresses nuclear accumulation. However, binding of FGF-2 to the holoenzyme triggers its nuclear translocation. Since the substrate specificity of CK2α is dramatically changed by its association with CK2β, the control of the nucleocytoplasmic distribution of each subunit may represent a unique potential regulatory mechanism for CK2 activity.

A Wnt signaling pathway controls hox gene expression and neuroblast migration in C. elegans

Development ◽  
1999 ◽  
Vol 126 (1) ◽  
pp. 37-49 ◽  
Author(s):  
J.N. Maloof ◽  
J. Whangbo ◽  
J.M. Harris ◽  
G.D. Jongeward ◽  
C. Kenyon
Keyword(s):  
Gene Expression ◽  
Wnt Signaling ◽  
Wnt Pathway ◽  
Hox Genes ◽  
Wnt Signaling Pathway ◽  
Beta Catenin ◽  
Hox Gene ◽  
C Elegans ◽  
Neuroblast Migration ◽  
Pathway Gene

The specification of body pattern along the anteroposterior (A/P) body axis is achieved largely by the actions of conserved clusters of Hox genes. Limiting expression of these genes to localized regional domains and controlling the precise patterns of expression within those domains is critically important for normal patterning. Here we report that egl-20, a C. elegans gene required to activate expression of the Hox gene mab-5 in the migratory neuroblast QL, encodes a member of the Wnt family of secreted glycoproteins. We have found that a second Wnt pathway gene, bar-1, which encodes a beta-catenin/Armadillo-like protein, is also required for activation of mab-5 expression in QL. In addition, we describe the gene pry-1, which is required to limit expression of the Hox genes lin-39, mab-5 and egl-5 to their correct local domains. We find that egl-20, pry-1 and bar-1 all function in a linear genetic pathway with conserved Wnt signaling components, suggesting that a conserved Wnt pathway activates expression of mab-5 in the migratory neuroblast QL. Moreover, we find that members of this Wnt signaling system play a major role in both the general and fine-scale control of Hox gene expression in other cell types along the A/P axis.

TGF-(beta) type I receptor/ALK-5 and Smad proteins mediate epithelial to mesenchymal transdifferentiation in NMuMG breast epithelial cells

1999 ◽  
Vol 112 (24) ◽  
pp. 4557-4568 ◽  
Author(s):  
E. Piek ◽  
A. Moustakas ◽  
A. Kurisaki ◽  
C.H. Heldin ◽  
P. ten Dijke
Keyword(s):  
Transforming Growth Factor ◽  
Activin A ◽  
Nuclear Accumulation ◽  
Type I ◽  
Beta Catenin ◽  
Tgf Beta ◽  
Mesenchymal Transition ◽  
Smad Proteins ◽  
Mesenchymal Transformation ◽  
Alk 5

The capacities of different transforming growth factor-(beta) (TGF-(beta)) superfamily members to drive epithelial to mesenchymal transdifferentiation of the murine mammary epithelial cell line NMuMG were investigated. TGF-(beta)1, but not activin A or osteogenic protein-1 (OP-1)/bone morphogenetic protein-7 (BMP-7), was able to induce morphological transformation of NMuMG cells as shown by reorganisation of the actin cytoskeleton and relocalisation/downregulation of E-cadherin and (beta)-catenin, an effect that was abrogated by the more general serine/threonine kinase and protein kinase C inhibitor, staurosporine. TGF-(beta)1 bound to TGF-(beta) type I receptor (T(beta)R-I)/ALK-5 and T(beta)R-II, but not to activin type I receptor (ActR-I)/ALK-2. Activin A bound to ActR-IB/ALK-4 and ActR-II, and BMP-7 bound to ActR-I/ALK-2, BMP type I receptor (BMPR-I)/ALK-3, ActR-II and BMPR-II. TGF-(beta)1 and BMP-7 activated the Smad-binding element (SBE)(4) promoter with equal potency, whereas activin A had no effect. Transfection of constitutively active (CA)-ALK-4 activated the 3TP promoter to the same extent as TGF-(beta)1 and CA-ALK-5 indicating that activin signalling downstream of type I receptors was functional in NMuMG cells. In agreement with this, activin A induced low levels of plasminogen activator inhibitor I expression compared to the high induction by TGF-(beta)1. In contrast to activin A and BMP-7, TGF-(beta)1 strongly induced Smad2 phosphorylation. Consistent with these findings, TGF-(beta)1 induced the nuclear accumulation of Smad2 and/or Smad3. In addition, NMuMG cells transiently infected with adenoviral vectors expressing high level CA-ALK-5 exhibited full transdifferentiation. On the other hand, infections with low level CA-ALK-5, which alone did not result in transdifferentiation, together with Smad2 and Smad4, or with Smad3 and Smad4 led to transdifferentiation. In conclusion, TGF-(beta)1 signals potently and passes the activation threshold to evoke NMuMG cell transdifferentiation. The TGF-(beta) type I receptor (ALK-5) and its effector Smad proteins mediate the epithelial to mesenchymal transition. Activin A does not induce mesenchymal transformation, presumably because the number of activin receptors is limited, while BMP-7-initiated signalling cannot mediate transdifferentiation.

E-cadherin binding prevents beta-catenin nuclear localization and beta-catenin/LEF-1-mediated transactivation

1999 ◽  
Vol 112 (8) ◽  
pp. 1237-1245 ◽  
Author(s):  
S. Orsulic ◽  
O. Huber ◽  
H. Aberle ◽  
S. Arnold ◽  
R. Kemler
Keyword(s):  
Nuclear Localization ◽  
Es Cells ◽  
Embryonic Stem ◽  
Carcinoma Cells ◽  
Beta Catenin ◽  
Multifunctional Protein ◽  
Colon Carcinoma Cells ◽  
Cell Compartments ◽  
Enhancer Factor ◽  
E Cadherin

Beta-catenin is a multifunctional protein found in three cell compartments: the plasma membrane, the cytoplasm and the nucleus. The cell has developed elaborate ways of regulating the level and localization of beta-catenin to assure its specific function in each compartment. One aspect of this regulation is inherent in the structural organization of beta-catenin itself; most of its protein-interacting motifs overlap so that interaction with one partner can block binding of another at the same time. Using recombinant proteins, we found that E-cadherin and lymphocyte-enhancer factor-1 (LEF-1) form mutually exclusive complexes with beta-catenin; the association of beta-catenin with LEF-1 was competed out by the E-cadherin cytoplasmic domain. Similarly, LEF-1 and adenomatous polyposis coli (APC) formed separate, mutually exclusive complexes with beta-catenin. In Wnt-1-transfected C57MG cells, free beta-catenin accumulated and was able to associate with LEF-1. The absence of E-cadherin in E-cadherin-/- embryonic stem (ES) cells also led to an accumulation of free beta-catenin and its association with LEF-1, thereby mimicking Wnt signaling. beta-catenin/LEF-1-mediated transactivation in these cells was antagonized by transient expression of wild-type E-cadherin, but not of E-cadherin lacking the beta-catenin binding site. The potent ability of E-cadherin to recruit beta-catenin to the cell membrane and prevent its nuclear localization and transactivation was also demonstrated using SW480 colon carcinoma cells.

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