title: The function of heterodimeric AP-1 comprised of c-Jun and c-Fos in activin mediated Spemann organizer gene expression.
abstract: BACKGROUND
  Activator protein-1 (AP-1) is a mediator of BMP or FGF signaling during Xenopus embryogenesis. However, specific role of AP-1 in activin signaling has not been elucidated during vertebrate development.
  
  
  RESULTS
  We provide new evidence showing that overexpression of heterodimeric AP-1 comprised of c-jun and c-fos (AP-1(c-Jun/c-Fos)) induces the expression of BMP-antagonizing organizer genes (noggin, chordin and goosecoid) that were normally expressed by high dose of activin. AP-1(c-Jun/c-Fos) enhanced the promoter activities of organizer genes but reduced that of PV.1, a BMP4-response gene. A loss of function study clearly demonstrated that AP-1(c-Jun/c-Fos) is required for the activin-induced organizer and neural gene expression. Moreover, physical interaction of AP-1(c-Jun/c-Fos) and Smad3 cooperatively enhanced the transcriptional activity of goosecoid via direct binding on this promoter. Interestingly, Smad3 mutants at c-Jun binding site failed in regulation of organizer genes, indicating that these physical interactions are specifically necessary for the expression of organizer genes.
  
  
  CONCLUSIONS
  AP-1(c-Jun/c-Fos) plays a specific role in organizer gene expression in downstream of activin signal during early Xenopus embryogenesis.
authors.affiliation: Department of Biochemistry, College of Medicine, Hallym University, ChunCheon, Kangwon-Do, Republic of Korea.
authors.forename: Sung-Young
authors.initials: SY
authors.lastname: Lee
authors.forename: Jaeho
authors.initials: J
authors.lastname: Yoon
authors.forename: Hyun-Shik
authors.initials: HS
authors.lastname: Lee
authors.forename: Yoo-Seok
authors.initials: YS
authors.lastname: Hwang
authors.forename: Sang-Wook
authors.initials: SW
authors.lastname: Cha
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Jeong
authors.forename: Jong-Il
authors.initials: JI
authors.lastname: Kim
authors.forename: Jae-Bong
authors.initials: JB
authors.lastname: Park
authors.forename: Jae-Yong
authors.initials: JY
authors.lastname: Lee
authors.forename: SungChan
authors.initials: S
authors.lastname: Kim
authors.forename: Mae Ja
authors.initials: MJ
authors.lastname: Park
authors.forename: Zigang
authors.initials: Z
authors.lastname: Dong
authors.forename: Jaebong
authors.initials: J
authors.lastname: Kim
mesh_terms: D028341:Activins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D055415:Bone Morphogenetic Protein 4 / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D051956:Goosecoid Protein / Q000235:genetics / Q000378:metabolism; D047468:Immunoprecipitation; D017403:In Situ Hybridization; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D020897:Organizers, Embryonic / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D055503:Protein Multimerization; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism; D014982:Xenopus laevis; D000099176:Noggin Protein
chemical_list: D028341:Activins; D055415:Bone Morphogenetic Protein 4; D002352:Carrier Proteins; D006023:Glycoproteins; D051956:Goosecoid Protein; D036341:Intercellular Signaling Peptides and Proteins; D008156:Luciferases; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D051900:Smad3 Protein; D020825:T-Box Domain Proteins; D018808:Transcription Factor AP-1; D029867:Xenopus Proteins; D000099176:Noggin Protein; C116765:TBXT protein, Xenopus; C054234:chordin