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??? Nodal signaling, mediated through SMAD transcription factors, is necessary for pluripotency maintenance and endoderm commitment. We identified a new motif, termed SMAD complex-associated (SCA), that is bound by SMAD2/3/4 and FOXH1 in human embryonic stem cells (hESCs) and derived endoderm. We demonstrate that two basic helix-loop-helix (bHLH) proteins-HEB and E2A-bind the SCA motif at regions overlapping SMAD2/3 and FOXH1. Furthermore, we show that HEB and E2A associate with SMAD2/3 and FOXH1, suggesting they form a complex at critical target regions. This association is biologically important, as E2A is critical for mesendoderm specification, gastrulation, and Nodal signal transduction in Xenopus tropicalis embryos. Taken together, E proteins are novel Nodal signaling cofactors that associate with SMAD2/3 and FOXH1 and are necessary for mesendoderm differentiation.
???displayArticle.pubmedLink???
21828274
???displayArticle.pmcLink???PMC3182016 ???displayArticle.link???Genes Dev ???displayArticle.grants???[+]
Figure 4. e2a and heb are expressed during early development in X. tropicalis. (A) X. tropicalis embryos were analyzed by RTCR for expression of heb and e2a, from blastula stage through early neurula. Ornithine decarboxylase (odc) was used as a loading control. (B) Vegetal endoderm explants of stage 10.5 X. tropicalis express e2a at low levels, but not the mesoderm- specific gene xbra. (C) X. tropicalis embryos were analyzed by in situ hybridization for expression of e2a and heb at early gastrula stage (stage 10.5), at early tailbud stage (stage 22), and at late tailbud stage (32). (D) Bar graphs show the percentage of each motif present in Smad2/3 target regions during gastrulation in X. tropicalis as determined by ChIP-seq.
Figure 5. E2A is essential for gastrulation and gene expression in X. tropicalis. (A, right) X. tropicalis embryos were injected with a translation-blocking MO (e2a MO) directed against e2a, and assayed morphologically at stages 10.5 and 25. These were compared with uninjected controls (shown at left). (B) Blasto- pore lip formation in e2a MO-injected embryos can be restored by subsequent injection of mouse e2a mRNA. Using either in situ hybridization (C) or qRTCR (D), e2a MO-injected embryos were compared with controls for expression of molecular markers. qRTCR results represent at least four biological replicates. (E) e2a morphants and uninjected controls were in- jected in the animal pole at the four-cell stage with 10 pg of Activin mRNA or 40 pg of Xnr1 mRNA, and assayed for the presence of ectopic bottle cells. Representative embryos are shown at stage 11 in animal views.
Supplemental Figure 4 (Supports Figure 5). (A) Injection of 20 ng of HEB MO in both blastomeres at the 2-cell stage does not result in gross morphological defects at gastrulation (stage 10.5) or in early tailbud embryos (stage 22). (B) Co- injection of 10 ng of E2A MO with nuclear β-galactosidase mRNA in one blastomere at the 4-cell stage results in cell-autonomous inhibition of blastopore formation and of xbra expression. Red color represents red-gal substrate staining and marks the injected portion of the embryo. (C) Embryos co-injected with e2a MO and mouse e2a mRNA were compared to uninjected controls for expression of xbra (mesoderm) and sox17β (endoderm). While e2a MO injection led to downregulation of xbra, this was rescued by co-injection with mouse E2A mRNA.
tcf12 (transcription factor 12 (HTF4, helix-loop-helix transcription factors 4)) gene expression in Xenopus tropicalis embryos, NF stage 10.5, as assayed by in situ hybridization, blastoporal view, animal up.
tcf12 ( transcription factor 12 (HTF4, helix-loop-helix transcription factors 4) ) gene expression in Xenopus tropicalis embryos, NF stage 22, as assayed by in situ hybridization, lateral view, anteriorleft, dorsal up.
tcf12 (transcription factor 12 (HTF4, helix-loop-helix transcription factors 4)) gene expression in Xenopus tropicalis embryo, NF stage 32, assayed by in situ hybridization, lateral view, anteriorleft, dorsal up.
Agius,
Endodermal Nodal-related signals and mesoderm induction in Xenopus.
2000, Pubmed,
Xenbase
Agius,
Endodermal Nodal-related signals and mesoderm induction in Xenopus.
2000,
Pubmed
,
Xenbase
Attisano,
Smads as transcriptional co-modulators.
2000,
Pubmed
Attisano,
The transcriptional role of Smads and FAST (FoxH1) in TGFbeta and activin signalling.
2001,
Pubmed
,
Xenbase
Bain,
E2A deficiency leads to abnormalities in alphabeta T-cell development and to rapid development of T-cell lymphomas.
1997,
Pubmed
Bain,
E2A proteins are required for proper B cell development and initiation of immunoglobulin gene rearrangements.
1994,
Pubmed
Barndt,
Functions of E2A-HEB heterodimers in T-cell development revealed by a dominant negative mutation of HEB.
2000,
Pubmed
Barndt,
A novel role for HEB downstream or parallel to the pre-TCR signaling pathway during alpha beta thymopoiesis.
1999,
Pubmed
Besser,
Expression of nodal, lefty-a, and lefty-B in undifferentiated human embryonic stem cells requires activation of Smad2/3.
2004,
Pubmed
Caudy,
daughterless, a Drosophila gene essential for both neurogenesis and sex determination, has sequence similarities to myc and the achaete-scute complex.
1988,
Pubmed
Conlon,
A primary requirement for nodal in the formation and maintenance of the primitive streak in the mouse.
1994,
Pubmed
Dahle,
Nodal signaling recruits the histone demethylase Jmjd3 to counteract polycomb-mediated repression at target genes.
2010,
Pubmed
Eimon,
Effects of heterodimerization and proteolytic processing on Derrière and Nodal activity: implications for mesoderm induction in Xenopus.
2002,
Pubmed
,
Xenbase
Faure,
Endogenous patterns of TGFbeta superfamily signaling during early Xenopus development.
2000,
Pubmed
,
Xenbase
Feldman,
Zebrafish organizer development and germ-layer formation require nodal-related signals.
1998,
Pubmed
Feldman,
Nodal-related signals establish mesendodermal fate and trunk neural identity in zebrafish.
2000,
Pubmed
,
Xenbase
Germain,
Homeodomain and winged-helix transcription factors recruit activated Smads to distinct promoter elements via a common Smad interaction motif.
2000,
Pubmed
,
Xenbase
Hemmati-Brivanlou,
A truncated activin receptor inhibits mesoderm induction and formation of axial structures in Xenopus embryos.
1992,
Pubmed
,
Xenbase
Henthorn,
Two distinct transcription factors that bind the immunoglobulin enhancer microE5/kappa 2 motif.
1990,
Pubmed
Hoodless,
FoxH1 (Fast) functions to specify the anterior primitive streak in the mouse.
2001,
Pubmed
Hoodless,
Dominant-negative Smad2 mutants inhibit activin/Vg1 signaling and disrupt axis formation in Xenopus.
1999,
Pubmed
,
Xenbase
Hu,
HEB, a helix-loop-helix protein related to E2A and ITF2 that can modulate the DNA-binding ability of myogenic regulatory factors.
1992,
Pubmed
Inman,
SB-431542 is a potent and specific inhibitor of transforming growth factor-beta superfamily type I activin receptor-like kinase (ALK) receptors ALK4, ALK5, and ALK7.
2002,
Pubmed
Khokha,
Techniques and probes for the study of Xenopus tropicalis development.
2002,
Pubmed
,
Xenbase
Kim,
Chromatin and transcriptional signatures for Nodal signaling during endoderm formation in hESCs.
2011,
Pubmed
Labbé,
Smad2 and Smad3 positively and negatively regulate TGF beta-dependent transcription through the forkhead DNA-binding protein FAST2.
1998,
Pubmed
,
Xenbase
Lai,
Ethidium bromide provides a simple tool for identifying genuine DNA-independent protein associations.
1992,
Pubmed
Luxardi,
Distinct Xenopus Nodal ligands sequentially induce mesendoderm and control gastrulation movements in parallel to the Wnt/PCP pathway.
2010,
Pubmed
,
Xenbase
McLean,
GREAT improves functional interpretation of cis-regulatory regions.
2010,
Pubmed
Murre,
A new DNA binding and dimerization motif in immunoglobulin enhancer binding, daughterless, MyoD, and myc proteins.
1989,
Pubmed
Osada,
Xenopus nodal-related signaling is essential for mesendodermal patterning during early embryogenesis.
1999,
Pubmed
,
Xenbase
Pan,
A new FACS approach isolates hESC derived endoderm using transcription factors.
2011,
Pubmed
Piccolo,
The head inducer Cerberus is a multifunctional antagonist of Nodal, BMP and Wnt signals.
1999,
Pubmed
,
Xenbase
Pogoda,
The zebrafish forkhead transcription factor FoxH1/Fast1 is a modulator of nodal signaling required for organizer formation.
2000,
Pubmed
Schier,
Nodal signaling in vertebrate development.
2003,
Pubmed
Teo,
Pluripotency factors regulate definitive endoderm specification through eomesodermin.
2011,
Pubmed
Vallier,
Activin/Nodal signalling maintains pluripotency by controlling Nanog expression.
2009,
Pubmed
Varlet,
nodal expression in the primitive endoderm is required for specification of the anterior axis during mouse gastrulation.
1997,
Pubmed
Weinstein,
Failure of egg cylinder elongation and mesoderm induction in mouse embryos lacking the tumor suppressor smad2.
1998,
Pubmed
,
Xenbase
Xu,
NANOG is a direct target of TGFbeta/activin-mediated SMAD signaling in human ESCs.
2008,
Pubmed
Zhuang,
The helix-loop-helix gene E2A is required for B cell formation.
1994,
Pubmed
Zhuang,
Functional replacement of the mouse E2A gene with a human HEB cDNA.
1998,
Pubmed
Zhuang,
B-lymphocyte development is regulated by the combined dosage of three basic helix-loop-helix genes, E2A, E2-2, and HEB.
1996,
Pubmed
