Xenopus fibrillin regulates directed convergence and extension

Area of Science:

• Developmental Biology
• Cell Biology
• Extracellular Matrix Biology

Background:

• Fibrillins are known to be involved in human diseases affecting adult tissues, such as Marfan syndrome.
• While fibrillins are present in embryos, their specific roles in early development have not been previously established.
• Gastrulation is a critical embryonic process involving extensive cell movements and tissue patterning.

Purpose of the Study:

• To investigate the role of Xenopus fibrillin (XF) during early embryonic development, specifically at gastrulation.
• To determine if fibrillins play a role in the cellular processes underlying gastrulation, such as cell motility and tissue extension.

Main Methods:

• Expression of truncated Xenopus fibrillin (XF) forms in embryos to assess dominant-negative effects on fibril assembly and gastrulation.
• Injection of a synthetic peptide containing a cell-binding domain of XF into embryos to study its impact on gastrulation and fibril assembly.
• Morpholino-mediated knockdown of XF translation in embryos to evaluate its necessity for normal gastrulation and directed extension.

Main Results:

• Expression of truncated XF disrupted gastrulation and inhibited polarized cell motility, crucial for convergence and extension.
• Synthetic peptide injection caused acute gastrulation failure and defective fibrillin fibril assembly, highlighting the peptide's role.
• XF knockdown perturbed gastrulation and directed extension, confirming the essentiality of native fibrillin.

Conclusions:

• Native Xenopus fibrillin is indispensable for directed convergent extension in the presumptive notochord during gastrulation.
• Fibrillin plays a critical role in regulating cell motility and tissue morphogenesis essential for embryonic development.
• These findings establish a novel early developmental function for fibrillin proteins.