Noggin1 and Follistatin-like2 function redundantly to Chordin to antagonize BMP activity

Area of Science:

• Developmental Biology
• Molecular Biology
• Genetics

Background:

• The dorso-ventral (D/V) axis in Xenopus is established by bone morphogenetic protein (Bmp) signaling.
• Antagonists like Noggin, Chordin, and Follistatin modulate Bmp activity to specify the D/V axis.

Purpose of the Study:

• To investigate the individual and combined roles of noggin1 (nog1), chordin (chd), and follistatin-like 2 (fstl2) in Xenopus D/V axis patterning.
• To identify the key anti-Bmp factors responsible for D/V axis formation.

Main Methods:

• Gene inactivation via morpholino-based knockdown of nog1, chd, and fstl2 in Xenopus embryos.
• Phenotypic analysis of D/V axis patterning in single and multiple gene knockdowns.

Main Results:

• Inactivation of nog1 alone does not disrupt D/V patterning but significantly enhances the chordin (chd) phenotype, indicating functional redundancy.
• Follistatin-like 2 (fstl2) is expressed during early gastrulation and its inactivation also enhances the chd phenotype.
• Simultaneous inactivation of chd, nog1, and fstl2 results in a high penetrance of the ventralization phenotype, suggesting a combined role.

Conclusions:

• Chordin is the principal antagonist regulating the Bmp gradient for D/V axis specification.
• Noggin1 and Fstl2 exhibit redundant anti-Bmp activities, contributing to the formation of dorsal and dorso-lateral tissues, particularly at blastula and gastrula stages.