Extracellular volume expansion drives vertebrate axis elongation

Area of Science:

• Developmental biology
• Cellular mechanics
• Molecular signaling

Background:

• Vertebrate body plan establishment relies on head-to-tail embryonic tissue elongation.
• The underlying mechanical processes of this elongation, particularly involving the presomitic mesoderm (PSM), are not well understood.

Purpose of the Study:

• To investigate the autonomous elongation capacity of avian PSM explants.
• To elucidate the mechanisms driving PSM elongation and its contribution to embryonic development.
• To identify the molecular pathways regulating this process.

Main Methods:

• In vitro culture of avian PSM explants under physical confinement.
• Analysis of tissue volumetric expansion and cellular motility.
• Investigation of fibroblast growth factor (FGF) signaling pathways and hyaluronic acid (HA) production.

Main Results:

• Avian PSM explants exhibit autonomous elongation when confined, generating a pushing force for posterior embryonic growth.
• Tissue elongation is driven by volumetric expansion due to increased extracellular fraction and cellular motility.
• FGF signaling stimulates glycolysis-dependent hyaluronic acid (HA) production, essential for posterior PSM expansion.

Conclusions:

• Body axis elongation is mechanistically linked to tissue expansion.
• Metabolic control of extracellular matrix production, downstream of FGF signaling, is a key regulator of PSM elongation.
• This study provides novel insights into the interplay between signaling, metabolism, and mechanics in embryonic development.