Linked Life Data

16775002

Source:http://linkedlifedata.com/resource/pubmed/id/16775002

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
14
pubmed:dateCreated
2006-6-23
pubmed:abstractText
Dorsoventral (DV) axis formation of the vertebrate embryo is controlled by the maternal genome and is subsequently refined zygotically. In the zygote, repression of ventralizing Bmp activity on the dorsal side through chordin and noggin is crucial for establishment of a dorsally located organizer. This interplay generates a zygotic Bmp activity gradient that defines distinct positional values along the DV axis. The maternal processes that control expression of the zygotic genes implicated in DV patterning are largely unknown. spiel-ohne-grenzen (spg/pou2) is a maternally and zygotically expressed zebrafish gene that encodes the POU domain transcription factor Pou2, an ortholog of mammalian Oct4/Pou5f1. We show that embryos that are genetically depleted of both maternal and zygotic pou2 function (MZspg) exhibit extreme DV patterning defects and, independently, a blastoderm-specific arrest of epiboly. Dorsal tissues expand to the ventral side at the expense of ventrolateral tissue in MZspg embryos. Dorsally expressed Bmp-antagonists, such as Chd and Nog1, and Gsc are ectopically activated at ventral levels in MZspg. Lack of ventral specification is apparent very early, suggesting that maternal processes are affected in MZspg. Indeed, maternal pou2 function is necessary to initiate zygotic expression of ventrally expressed genes such as bmp2b and bmp4, and for proper activation of bmp7, vox, vent and eve1. A constitutively active Alk8-TGFbeta-receptor can ectopically induce bmp2b and bmp4 and rescues the dorsalization of MZspg. This indicates that pou2 acts upstream of Alk8, a maternally provided receptor implicated in the activation of zygotic bmp2b and bmp4 transcription. Consistent with this possibility, Bmp gene misexpression can rescue MZspg embryos, indicating that TGFbeta-mediated signal transduction itself is intact in absence of Pou2. Inhibition of Fgf signaling, another pathway with early dorsalizing activity, can also restore and even ventralize MZspg embryos. The requirement for pou2 to initiate bmp2b expression can therefore be bypassed by releasing the repressive function of Fgf signaling upon bmp2b transcription. In transplantation experiments, we find that dorsalized cells from prospective ventrolateral regions of MZspg embryos are non cell-autonomously respecified to a ventral fate within wild-type host embryos. Analysis of pou2 mRNA injected MZspg embryos shows that pou2 is required on the ventral side of cleavage stage embryos. Based on the maternal requirement for pou2 in ventral specification, we propose that ventral specification employs an active, pou2-dependent maternal induction step, rather than a default ventralizing program.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0950-1991
pubmed:author
pubmed:issnType
Print
pubmed:volume
133
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2757-70
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed-meshheading:16775002-Activin Receptors, Type I, pubmed-meshheading:16775002-Animals, pubmed-meshheading:16775002-Body Patterning, pubmed-meshheading:16775002-Bone Morphogenetic Proteins, pubmed-meshheading:16775002-Cell Polarity, pubmed-meshheading:16775002-Cell Transplantation, pubmed-meshheading:16775002-Embryo, Nonmammalian, pubmed-meshheading:16775002-Epistasis, Genetic, pubmed-meshheading:16775002-Fibroblast Growth Factor 8, pubmed-meshheading:16775002-Gene Expression Regulation, Developmental, pubmed-meshheading:16775002-Germ Layers, pubmed-meshheading:16775002-In Situ Hybridization, pubmed-meshheading:16775002-Morphogenesis, pubmed-meshheading:16775002-Octamer Transcription Factor-3, pubmed-meshheading:16775002-Signal Transduction, pubmed-meshheading:16775002-Zebrafish, pubmed-meshheading:16775002-Zebrafish Proteins
pubmed:year
2006
pubmed:articleTitle
Maternal control of vertebrate dorsoventral axis formation and epiboly by the POU domain protein Spg/Pou2/Oct4.
pubmed:affiliation
Biotechnology Center and Center for Regenerative Therapies, University of Technology (TU) Dresden, Pfotenhauerstrasse 108, D-01307 Dresden, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't