title: Xnrs and activin regulate distinct genes during Xenopus development: activin regulates cell division.
abstract: BACKGROUND
  The mesoderm of the amphibian embryo is formed through an inductive interaction in which vegetal cells of the blastula-staged embryo act on overlying equatorial cells. Candidate mesoderm-inducing factors include members of the transforming growth factor type beta family such as Vg1, activin B, the nodal-related proteins and derrière.
  
  
  RESULTS
  Microarray analysis reveals different functions for activin B and the nodal-related proteins during early Xenopus development. Inhibition of nodal-related protein function causes the down-regulation of regionally expressed genes such as chordin, dickkopf and XSox17alpha/beta, while genes that are mis-regulated in the absence of activin B tend to be more widely expressed and, interestingly, include several that are involved in cell cycle regulation. Consistent with the latter observation, cells of the involuting dorsal axial mesoderm, which normally undergo cell cycle arrest, continue to proliferate when the function of activin B is inhibited.
  
  
  CONCLUSIONS
  These observations reveal distinct functions for these two classes of the TGF-beta family during early Xenopus development, and in doing so identify a new role for activin B during gastrulation.
authors.affiliation: Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Zoology, University of Cambridge, Cambridge, United Kindgom.
authors.forename: Joana M
authors.initials: JM
authors.lastname: Ramis
authors.forename: Clara
authors.initials: C
authors.lastname: Collart
authors.forename: James C
authors.initials: JC
authors.lastname: Smith
mesh_terms: D028341:Activins / Q000037:antagonists & inhibitors / Q000502:physiology*; D000818:Animals; D019521:Body Patterning / Q000235:genetics / Q000502:physiology*; D002455:Cell Division / Q000502:physiology*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D054262:Gastrulation / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental; D018816:Genes, cdc; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis / Q000235:genetics; D008648:Mesoderm / Q000166:cytology; D055456:Nodal Signaling Ligands / Q000037:antagonists & inhibitors / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014981:Xenopus / Q000196:embryology; D029867:Xenopus Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D055456:Nodal Signaling Ligands; D016376:Oligonucleotides, Antisense; D029867:Xenopus Proteins; C044147:activin B; C100866:cer1 protein, Xenopus; D028341:Activins