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Updated: May 30, 2026

Chromatin Immunoprecipitation Assay for Tissue-specific Genes using Early-stage Mouse Embryos
Published on: April 29, 2011
The function of heterodimeric AP-1 comprised of c-Jun and c-Fos in activin mediated Spemann organizer gene expression
Sung-Young Lee1, Jaeho Yoon, Hyun-Shik Lee
1Department of Biochemistry, College of Medicine, Hallym University, ChunCheon, Kangwon-Do, Republic of Korea.
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.
Methodology/Principal Findings:
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/Significance:
AP-1(c-Jun/c-Fos) plays a specific role in organizer gene expression in downstream of activin signal during early Xenopus embryogenesis.
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