Tissue-tissue interaction-triggered calcium elevation is required for cell polarization during Xenopus gastrulation

Area of Science:

• Developmental Biology
• Cell Biology
• Biophysics

Background:

• Cell polarity is vital for embryonic development, guiding cell morphology and function.
• The precise trigger for initiating cell polarization remains largely unknown.
• Previous work identified tissue boundaries as important for chordamesodermal cell polarity in Xenopus laevis.

Purpose of the Study:

• To investigate the role of intracellular calcium dynamics in cell polarization at tissue boundaries.
• To identify the trigger mechanisms underlying cell polarization during Xenopus embryogenesis.

Main Methods:

• Co-culture of different Xenopus embryonic tissues (chordamesoderm with ectoderm or lateral mesoderm).
• Monitoring intracellular calcium dynamics using live imaging.
• Applying physical forces to explants and observing cellular responses.
• Genetic manipulation to inhibit calcium elevation and assess purinergic receptor function.

Main Results:

• Chordamesodermal cells at heterogeneous tissue boundaries showed increased intracellular calcium elevation compared to homogeneous boundaries.
• Inhibition of calcium elevation blocked cell polarization.
• Physical force application and cell migration beneath a barrier induced calcium elevation and cell polarization.
• A purinergic receptor, involved in mechanosensing, was essential for calcium elevation and polarization.

Conclusions:

• Tissue-tissue interactions generate mechanical forces that initiate cell polarization.
• Transient increases in intracellular calcium, mediated by purinergic receptors, are key events in this process.
• This study proposes a model where mechanical cues at tissue boundaries drive coordinated cell polarization via calcium signaling.