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Development 2007 Feb 01;1344:769-77. doi: 10.1242/dev.02778.
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Negative regulation of Activin/Nodal signaling by SRF during Xenopus gastrulation.

Yun CH , Choi SC , Park E , Kim SJ , Chung AS , Lee HK , Lee HJ , Han JK .

Activin/Nodal signaling is essential for germ-layer formation and axial patterning during embryogenesis. Recent evidence has demonstrated that the intra- or extracellular inhibition of this signaling is crucial for ectoderm specification and correct positioning of mesoderm and endoderm. Here, we analyzed the function of Xenopus serum response factor (XSRF) in establishing germ layers during early development. XSRF transcripts are restricted to the animal pole ectoderm in Xenopus early embryos. Ectopic expression of XSRF RNA suppresses mesoderm induction, both in the marginal zone in vivo and caused by Activin/Nodal signals in animal caps. Dominant-negative mutant or antisense morpholino oligonucleotide-mediated inhibition of XSRF function expands the expression of mesendodermal genes toward the ectodermal territory and enhances the inducing activity of the Activin signal. SRF interacts with Smad2 and FAST-1, and inhibits the formation of the Smad2-FAST-1 complex induced by Activin. These results suggest that XSRF might act to ensure proper mesoderm induction in the appropriate region by inhibiting the mesoderm-inducing signals during early embryogenesis.

PubMed ID: 17259304
Article link: Development
Grant support: [+]

Species referenced: Xenopus
Genes referenced: chrd.1 foxh1 gsc inhbb krt12.4 mix1 msx1 myc myod1 nodal nodal1 odc1 smad2 smad4 sox17b.1 srf tbxt vegt wnt8a zic3
Antibodies: Smad2 Ab10 Smad2 Ab2 Smad4 Ab1 Srf Ab1
Morpholinos: srf MO1 srf MO2

Article Images: [+] show captions