scholarly journals LvNotch signaling plays a dual role in regulating the position of the ectoderm-endoderm boundary in the sea urchin embryo

Development ◽  
2001 ◽  
Vol 128 (12) ◽  
pp. 2221-2232 ◽  
Author(s):  
David R. Sherwood ◽  
David R. McClay
Keyword(s):  
Sea Urchin ◽  
Molecular Mechanisms ◽  
Early Embryo ◽  
Notch Receptor ◽  
Dominant Negative ◽  
Autonomous Function ◽  
Sea Urchin Embryo ◽  
Dominant Negative Form ◽  
A Cell ◽  
Negative Form

The molecular mechanisms guiding the positioning of the ectoderm-endoderm boundary along the animal-vegetal axis of the sea urchin embryo remain largely unknown. We report here a role for the sea urchin homolog of the Notch receptor, LvNotch, in mediating the position of this boundary. Overexpression of an activated form of LvNotch throughout the embryo shifts the ectoderm-endoderm boundary more animally along the animal-vegetal axis, whereas expression of a dominant negative form shifts the border vegetally. Mosaic experiments that target activated and dominant negative forms of LvNotch into individual blastomeres of the early embryo, combined with lineage analyses, further reveal that LvNotch signaling mediates the position of this boundary by distinct mechanisms within the animal versus vegetal portions of the embryo. In the animal region of the embryo, LvNotch signaling acts cell autonomously to promote endoderm formation more animally, while in the vegetal portion, LvNotch signaling also promotes the ectoderm-endoderm boundary more animally, but through a cell non-autonomous mechanism. We further demonstrate that vegetal LvNotch signaling controls the localization of nuclear β-catenin at the ectoderm-endoderm boundary. Based on these results, we propose that LvNotch signaling promotes the position of the ectoderm-endoderm boundary more animally via two mechanisms: (1) a cell-autonomous function within the animal region of the embryo, and (2) a cell non-autonomous role in the vegetal region that regulates a signal(s) mediating ectoderm-endoderm position, possibly through the control of nuclear β-catenin at the boundary.

Abstract 1473: Identification Of A New NRSF-binding Partner, Zfp90, Which Negatively Regulates The Repression Activity Of NRSF, A Critical Transcriptional Regulator Of Cardiac Fetal Gene Program

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Masao Murakami ◽  
Koichiro Kuwahara ◽  
Masaki Harada ◽  
Yasuaki Nakagawa ◽  
Satoru Usami ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Dominant Negative ◽  
Assay System ◽  
Negative Regulator ◽  
Binding Partner ◽  
Arrhythmic Death ◽  
Dominant Negative Form ◽  
Cardiac Gene ◽  
Hybrid Screening ◽  
Negative Form

Neuron-restrictive silencer factor, NRSF is a Zn-finger transcription factor that specifically binds to DNA sequence called NRSE to repress the transcription. NRSF is involved in various biological processes, such as neuronal differentiation, carcinogenesis, and cardiac homeostasis. We previously reported that NRSF regulates the transcription of multiple fetal cardiac genes. Cardiac-specific overexpression of a dominant-negative form of NRSF in mice induced reactivation of fetal cardiac gene program, cardiac dysfunction, and sudden arrhythmic death, suggesting NRSF plays important roles in normal cardiac homeostasis. However, the molecular mechanisms or signaling pathways that regulate the activity of NRSF have not been well understood. In an attempt to clarify the regulators of NRSF, we performed yeast two-hybrid screening using NRSF as bait and identified Zfp90 as NRSF-binding protein. NRSF and Zfp90 co-localize in the nuclear, and Zn-finger domain of NRSF specifically interacted with KRAB domain of Zfp90. To monitor the activity of NRSF sensitively, we made NRSF-responsive reporters using NRSE sequence of BNP promoter and established assay system for estimating the NRSF activity. In this assay system, expression of NRSF repressed the reporter activity and co-expression of Zfp90 restored it. Furthermore the expression levels of Zfp90 were elevated in the hearts with cardiomyopathy. These results suggest that Zfp90 functions as a negative regulator of NRSF and contributes to the genetic remodeling during the development of cardiomyopathy..

scholarly journals β-Catenin is essential for patterning the maternally specified animal-vegetal axis in the sea urchin embryo

1998 ◽  
Vol 95 (16) ◽  
pp. 9343-9348 ◽  
Author(s):  
Athula H. Wikramanayake ◽  
Ling Huang ◽  
William H. Klein
Keyword(s):  
Sea Urchin ◽  
Molecular Mechanisms ◽  
Early Embryo ◽  
Cell Fates ◽  
Cell Stage ◽  
Signal Transduction Cascade ◽  
Sea Urchin Embryos ◽  
Sea Urchin Embryo ◽  
Vegetal Pole ◽  
Vegetal Cell

In sea urchin embryos, the animal-vegetal axis is specified during oogenesis. After fertilization, this axis is patterned to produce five distinct territories by the 60-cell stage. Territorial specification is thought to occur by a signal transduction cascade that is initiated by the large micromeres located at the vegetal pole. The molecular mechanisms that mediate the specification events along the animal–vegetal axis in sea urchin embryos are largely unknown. Nuclear β-catenin is seen in vegetal cells of the early embryo, suggesting that this protein plays a role in specifying vegetal cell fates. Here, we test this hypothesis and show that β-catenin is necessary for vegetal plate specification and is also sufficient for endoderm formation. In addition, we show that β-catenin has pronounced effects on animal blastomeres and is critical for specification of aboral ectoderm and for ectoderm patterning, presumably via a noncell-autonomous mechanism. These results support a model in which a Wnt-like signal released by vegetal cells patterns the early embryo along the animal–vegetal axis. Our results also reveal similarities between the sea urchin animal–vegetal axis and the vertebrate dorsal–ventral axis, suggesting that these axes share a common evolutionary origin.

Cis-interactions between Delta and Notch modulate neurogenic signalling in Drosophila

Development ◽  
1998 ◽  
Vol 125 (22) ◽  
pp. 4531-4540 ◽  
Author(s):  
T.L. Jacobsen ◽  
K. Brennan ◽  
A.M. Arias ◽  
M.A. Muskavitch
Keyword(s):  
Ectopic Expression ◽  
Notch Signalling ◽  
Dominant Negative ◽  
Notch Signalling Pathway ◽  
Dominant Negative Form ◽  
A Cell ◽  
Developmental Contexts ◽  
Tormogen Cell ◽  
To Receive ◽  
Negative Form

We find that ectopic expression of Delta or Serrate in neurons within developing bristle organs is capable of non-autonomously inducing the transformation of the pre-trichogen cell into a tormogen cell in a wide variety of developmental contexts. The frequencies at which Delta can induce these transformations are dependent on the level of ectopic Delta expression and the levels of endogenous Notch signalling pathway components. The pre-trichogen cell becomes more responsive to Delta- or Serrate-mediated transformation when the level of endogenous Delta is reduced and less responsive when the dosage of endogenous Delta is increased, supporting the hypothesis that Delta interferes autonomously with the ability of a cell to receive either signal. We also find that a dominant-negative form of Notch, ECN, is capable of autonomously interfering with the ability of a cell to generate the Delta signal. When the region of Notch that mediates trans-interactions between Delta and the Notch extracellular domain is removed from ECN, the ability of Delta to signal is restored. Our findings imply that cell-autonomous interactions between Delta and Notch can affect the ability of a cell to generate and to transduce a Delta-mediated signal. Finally, we present evidence that the Fringe protein can interfere with Delta- and Serrate-mediated signalling within developing bristle organs, in contrast to previous reports of the converse effects of Fringe on Delta signalling in the developing wing.

LvNotch signaling mediates secondary mesenchyme specification in the sea urchin embryo

Development ◽  
1999 ◽  
Vol 126 (8) ◽  
pp. 1703-1713 ◽  
Author(s):  
D.R. Sherwood ◽  
D.R. McClay
Keyword(s):  
Sea Urchin ◽  
Cell Types ◽  
Notch Signaling Pathway ◽  
Notch Receptor ◽  
Dominant Negative ◽  
Sea Urchin Embryo ◽  
Numerous Cell ◽  
Vertebrate Embryos ◽  
Mesenchyme Cells ◽  
Molecular Bases

Cell-cell interactions are thought to regulate the differential specification of secondary mesenchyme cells (SMCs) and endoderm in the sea urchin embryo. The molecular bases of these interactions, however, are unknown. We have previously shown that the sea urchin homologue of the LIN-12/Notch receptor, LvNotch, displays dynamic patterns of expression within both the presumptive SMCs and endoderm during the blastula stage, the time at which these two cell types are thought to be differentially specified (Sherwood, D. R. and McClay, D. R. (1997) Development 124, 3363–3374). The LIN-12/Notch signaling pathway has been shown to mediate the segregation of numerous cell types in both invertebrate and vertebrate embryos. To directly examine whether LvNotch signaling has a role in the differential specification of SMCs and endoderm, we have overexpressed activated and dominant negative forms of LvNotch during early sea urchin development. We show that activation of LvNotch signaling increases SMC specification, while loss or reduction of LvNotch signaling eliminates or significantly decreases SMC specification. Furthermore, results from a mosaic analysis of LvNotch function as well as endogenous LvNotch expression strongly suggest that LvNotch signaling acts autonomously within the presumptive SMCs to mediate SMC specification. Finally, we demonstrate that the expansion of SMCs seen with activation of LvNotch signaling comes at the expense of presumptive endoderm cells, while loss of SMC specification results in the endoderm expanding into territory where SMCs usually arise. Taken together, these results offer compelling evidence that LvNotch signaling directly specifies the SMC fate, and that this signaling is critical for the differential specification of SMCs and endoderm in the sea urchin embryo.

Localization and expression of msp130, a primary mesenchyme lineage-specific cell surface protein in the sea urchin embryo

Development ◽  
1987 ◽  
Vol 101 (2) ◽  
pp. 255-265 ◽  
Author(s):  
J.A. Anstrom ◽  
J.E. Chin ◽  
D.S. Leaf ◽  
A.L. Parks ◽  
R.A. Raff
Keyword(s):  
Cell Surface ◽  
Sea Urchin ◽  
Sea Water ◽  
Surface Protein ◽  
Specific Cell ◽  
Cell Surface Protein ◽  
Sea Urchin Embryo ◽  
A Cell ◽  
Mesenchyme Cells ◽  
Primary Mesenchyme Cells

In this report, we use a monoclonal antibody (B2C2) and antibodies against a fusion protein (Leaf et al. 1987) to characterize msp130, a cell surface protein specific to the primary mesenchyme cells of the sea urchin embryo. This protein first appears on the surface of these cells upon ingression into the blastocoel. Immunoelectronmicroscopy shows that msp130 is present in the trans side of the Golgi apparatus and on the extracellular surface of primary mesenchyme cells. Four precursor proteins to msp130 are identified and we show that B2C2 recognizes only the mature form of msp130. We demonstrate that msp130 contains N-linked carbohydrate groups and that the B2C2 epitope is sensitive to endoglycosidase F digestion. Evidence that msp130 is apparently a sulphated glycoprotein is presented. The recognition of the B2C2 epitope of msp130 is disrupted when embryos are cultured in sulphate-free sea water. In addition, two-dimensional immunoblots show that msp130 is an acidic protein that becomes substantially less acidic in the absence of sulphate. We also show that two other independently derived monoclonal antibodies, IG8 (McClay et al. 1983; McClay, Matranga & Wessel, 1985) and 1223 (Carson et al. 1985), recognize msp130, and suggest this protein to be a major cell surface antigen of primary mesenchyme cells.

GSK3beta/shaggy mediates patterning along the animal-vegetal axis of the sea urchin embryo

Development ◽  
1998 ◽  
Vol 125 (13) ◽  
pp. 2489-2498 ◽  
Author(s):  
F. Emily-Fenouil ◽  
C. Ghiglione ◽  
G. Lhomond ◽  
T. Lepage ◽  
C. Gache
Keyword(s):  
Sea Urchin ◽  
Wnt Pathway ◽  
Dominant Negative ◽  
Early Gene ◽  
Expression Domain ◽  
Animal Pole ◽  
Axial Patterning ◽  
Sea Urchin Embryo ◽  
Vegetal Pole ◽  
Dominant Negative Activity

In the sea urchin embryo, the animal-vegetal axis is defined before fertilization and different embryonic territories are established along this axis by mechanisms which are largely unknown. Significantly, the boundaries of these territories can be shifted by treatment with various reagents including zinc and lithium. We have isolated and characterized a sea urchin homolog of GSK3beta/shaggy, a lithium-sensitive kinase which is a component of the Wnt pathway and known to be involved in axial patterning in other embryos including Xenopus. The effects of overexpressing the normal and mutant forms of GSK3beta derived either from sea urchin or Xenopus were analyzed by observation of the morphology of 48 hour embryos (pluteus stage) and by monitoring spatial expression of the hatching enzyme (HE) gene, a very early gene whose expression is restricted to an animal domain with a sharp border roughly coinciding with the future ectoderm / endoderm boundary. Inactive forms of GSK3beta predicted to have a dominant-negative activity, vegetalized the embryo and decreased the size of the HE expression domain, apparently by shifting the boundary towards the animal pole. These effects are similar to, but even stronger than, those of lithium. Conversely, overexpression of wild-type GSK3beta animalized the embryo and caused the HE domain to enlarge towards the vegetal pole. Unlike zinc treatment, GSK3beta overexpression thus appeared to provoke a true animalization, through extension of the presumptive ectoderm territory. These results indicate that in sea urchin embryos the level of GSKbeta activity controls the position of the boundary between the presumptive ectoderm and endoderm territories and thus, the relative extent of these tissue layers in late embryos. GSK3beta and probably other downstream components of the Wnt pathway thus mediate patterning both along the primary AV axis of the sea urchin embryo and along the dorsal-ventral axis in Xenopus, suggesting a conserved basis for axial patterning between invertebrate and vertebrate in deuterostomes.

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