Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
???displayArticle.abstract???
We compared the transcriptome in the developing notochord of Xenopus laevis embryos with that of other embryonic regions. A coordinated and intense activation of a large set of secretory pathway genes was observed in the notochord, but not in notochord precursors in the axial mesoderm at early gastrula stage. The genes encoding Xbp1 and Creb3l2 were also activated in the notochord. These two transcription factors are implicated in the activation of secretory pathway genes during the unfolded protein response, where cells react to the stress of a build-up of unfolded proteins in their endoplasmic reticulum. Xbp1 and Creb3l2 are differentially expressed but not differentially activated in the notochord. Reduction of expression of Xbp1 or Creb3l2 by injection of antisense morpholinos led to strong deficits in notochord but not somitic muscle development. In addition, the expression of some, but not all, genes encoding secretory proteins was inhibited by injection of xbp1 morpholinos. Furthermore, expression of activated forms of Xbp1 or Creb3l2 in animal explants could activate a similar subset of secretory pathway genes. We conclude that coordinated activation of a battery of secretory pathway genes mediated by Xbp1 and Creb/ATF factors is a characteristic and necessary feature of notochord formation.
Fig. 2. In situ hybridization of selected secretory pathway genes to Xenopus embryos. (A-K′) Embryos at stage 12.5 (A-K), stages 15-17 (A′-K′) and stages 28-32 (A′-K′). All of these genes show preferential expression in the notochord, and some also show expression in the pronephros (red triangle).
Fig. 3. XPB1 and Creb3l2 are involved in notochord formation. (A,B) In situ hybridization at stage 17 shows the preferential notochord expression of xbp1 (A) and creb3l2 (B). (C-J) Embryos were injected with control MO (C,E,G,I), a mixture of xbp1(n) and xbp1(s) MOs (D,H), or a mixture of creb3l2 A and creb3l2 B MOs (F,J). Embryos were stained with the notochord-specific antibody MZ15 (C-F), or the muscle-specific antibody 12-101 (G-J).
large1 (LARGE xylosyl- and glucuronyltransferase 1) gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage 28, lateral view, anteriorleft, dorsal up.
Adams,
The mechanics of notochord elongation, straightening and stiffening in the embryo of Xenopus laevis.
1990, Pubmed,
Xenbase
Adams,
The mechanics of notochord elongation, straightening and stiffening in the embryo of Xenopus laevis.
1990,
Pubmed
,
Xenbase Calfon,
IRE1 couples endoplasmic reticulum load to secretory capacity by processing the XBP-1 mRNA.
2002,
Pubmed Cao,
XBP1 forms a regulatory loop with BMP-4 and suppresses mesodermal and neural differentiation in Xenopus embryos.
2006,
Pubmed
,
Xenbase Coutinho,
Differential requirements for COPI transport during vertebrate early development.
2004,
Pubmed Dennis,
DAVID: Database for Annotation, Visualization, and Integrated Discovery.
2003,
Pubmed Duden,
ER-to-Golgi transport: COP I and COP II function (Review).
2003,
Pubmed Gansner,
Essential role for the alpha 1 chain of type VIII collagen in zebrafish notochord formation.
2008,
Pubmed Gawantka,
Gene expression screening in Xenopus identifies molecular pathways, predicts gene function and provides a global view of embryonic patterning.
1998,
Pubmed
,
Xenbase Harland,
In situ hybridization: an improved whole-mount method for Xenopus embryos.
1991,
Pubmed
,
Xenbase Haze,
Mammalian transcription factor ATF6 is synthesized as a transmembrane protein and activated by proteolysis in response to endoplasmic reticulum stress.
1999,
Pubmed Jiang,
Ascidian notochord morphogenesis.
2007,
Pubmed Kintner,
Monoclonal antibodies identify blastemal cells derived from dedifferentiating limb regeneration.
,
Pubmed
,
Xenbase Kondo,
OASIS, a CREB/ATF-family member, modulates UPR signalling in astrocytes.
2005,
Pubmed Kondo,
BBF2H7, a novel transmembrane bZIP transcription factor, is a new type of endoplasmic reticulum stress transducer.
2007,
Pubmed Lee,
Molecular mechanisms of COPII vesicle formation.
2007,
Pubmed Malacinski,
The structure of the anuran amphibian Notochord and a re-evaluation of its presumed role in early embryogenesis.
1982,
Pubmed
,
Xenbase Meyer,
Mammalian Sec61 is associated with Sec62 and Sec63.
2000,
Pubmed Parsons,
Zebrafish mutants identify an essential role for laminins in notochord formation.
2002,
Pubmed Pollard,
Essential and overlapping roles for laminin alpha chains in notochord and blood vessel formation.
2006,
Pubmed Ron,
Signal integration in the endoplasmic reticulum unfolded protein response.
2007,
Pubmed Savitz,
180-kD ribosome receptor is essential for both ribosome binding and protein translocation.
1993,
Pubmed Schröder,
The mammalian unfolded protein response.
2005,
Pubmed Scott,
Zebrafish notochordal basement membrane: signaling and structure.
2005,
Pubmed Sitia,
Quality control in the endoplasmic reticulum protein factory.
2003,
Pubmed Skach,
The expanding role of the ER translocon in membrane protein folding.
2007,
Pubmed Smith,
Biochemical specificity of Xenopus notochord.
1985,
Pubmed
,
Xenbase Stemple,
Mutations affecting development of the notochord in zebrafish.
1996,
Pubmed Stemple,
Structure and function of the notochord: an essential organ for chordate development.
2005,
Pubmed Tanegashima,
WGEF activates Rho in the Wnt-PCP pathway and controls convergent extension in Xenopus gastrulation.
2008,
Pubmed
,
Xenbase Yoshida,
XBP1 mRNA is induced by ATF6 and spliced by IRE1 in response to ER stress to produce a highly active transcription factor.
2001,
Pubmed Yuan,
Endoplasmic reticulum stress induced by tunicamycin disables germ layer formation in Xenopus laevis embryos.
2007,
Pubmed
,
Xenbase Yuan,
IRE1beta is required for mesoderm formation in Xenopus embryos.
2008,
Pubmed
,
Xenbase Zhao,
Xenopus X-box binding protein 1, a leucine zipper transcription factor, is involved in the BMP signaling pathway.
2003,
Pubmed
,
Xenbase Zhao,
Lrig3 regulates neural crest formation in Xenopus by modulating Fgf and Wnt signaling pathways.
2008,
Pubmed
,
Xenbase
