Cell size regulates human endoderm specification through actomyosin-dependent AMOT-YAP signaling

Area of Science:

• Cell biology
• Developmental biology
• Biophysics

Background:

• Cell size is a fundamental physical property influencing cell function.
• The role of cell size dynamics in stem cell specification is not well understood.
• Human pluripotent stem cells (hPSCs) differentiate into various cell types, including definitive endoderm (DE).

Purpose of the Study:

• To investigate the dynamic changes in cell size during hPSC differentiation into DE.
• To explore the impact of cell size modulation on DE differentiation.
• To elucidate the molecular mechanisms linking cell size reduction to DE specification.

Main Methods:

• Monitoring cell size changes during hPSC-to-DE differentiation.
• Applying hypertonic pressure and chemical treatments to induce cell size reduction.
• Investigating the role of mechanosensitive elements, including actomyosin, AMOT, and YAP.
• Utilizing live-cell imaging and biochemical assays.

Main Results:

• Cell size gradually decreased during DE differentiation, particularly on stiffer substrates.
• Accelerating cell size reduction via hypertonic pressure or chemical means significantly enhanced DE differentiation.
• Actomyosin activity was identified as a key mediator of both cell size reduction and DE differentiation.
• Cell size diminution promoted AMOT nuclear translocation, suppressing YAP activity and facilitating DE differentiation.

Conclusions:

• A novel link between cell size reduction and definitive endoderm differentiation in hPSCs was established.
• The mechanism involves actomyosin-dependent AMOT nuclear translocation and subsequent YAP inhibition.
• Osmotic pressure represents a promising strategy to promote human endodermal lineage differentiation.