The apical ECM preserves embryonic integrity and distributes mechanical stress during morphogenesis

Area of Science:

• Developmental Biology
• Cell Biology
• Biophysics

Background:

• Epithelia are surrounded by basal and apical extracellular matrices (ECM).
• The apical ECM's role, particularly the embryonic sheath in C. elegans, is less understood than the basal ECM.
• The embryonic sheath is hypothesized to aid embryonic elongation.

Purpose of the Study:

• To identify components of the C. elegans embryonic sheath.
• To investigate the function of these components in embryonic development and integrity.
• To elucidate the role of the apical ECM in mechanical stress transmission during morphogenesis.

Main Methods:

• RNA interference (RNAi) screen to identify sheath components.
• Laser nano-ablation to map stress fields.
• Loss-of-function experiments to assess protein function.

Main Results:

• NOAH-1 and NOAH-2, zona pellucida domain proteins, were identified as key sheath components.
• NOAH-1 and NOAH-2 function in parallel pathways with SYM-1, LET-4, and FBN-1/Fibrillin.
• Apical ECM proteins are vital for maintaining actomyosin-dependent stress and relaying mechanical signals from muscle contractions.

Conclusions:

• The apical ECM, including NOAH proteins, is essential for embryonic integrity and elongation in C. elegans.
• Apical ECM proteins mediate mechanical stress, contributing to morphogenesis.
• This study highlights the importance of the apical ECM in transmitting mechanical cues during embryonic development.