Mitotic cell rounding and epithelial thinning regulate lumen growth and shape

Area of Science:

• Developmental Biology
• Cell Biology
• Organogenesis

Background:

• Epithelial cavities are crucial for organ function, and their abnormal development can lead to diseases affecting organs like the kidney, brain, and inner ear.
• Understanding the mechanisms that control lumen dimensions is essential for addressing these morphogenetic anomalies.
• Current knowledge regarding the regulation of lumen size and shape during organ development remains limited.

Purpose of the Study:

• To investigate the dynamic processes governing lumen growth and shape determination in the developing zebrafish inner ear.
• To identify novel morphogenetic mechanisms responsible for anisotropic lumen expansion.
• To elucidate the cellular and mechanical contributions to lumen morphogenesis.

Main Methods:

• Live imaging of zebrafish inner ear development to quantitatively analyze 3D lumen growth dynamics.
• Genetic and chemical perturbations to investigate the roles of specific cellular processes.
• Laser microsurgery to probe the mechanical contributions of cell behaviors, such as mitotic rounding.

Main Results:

• Identified two novel mechanisms contributing to anisotropic lumen growth.
• Demonstrated that epithelial thinning, involving coordinated cell shape changes and fluid loss, drives cavity expansion.
• Revealed that apicobasal contraction by mitotic rounding cells mechanically promotes lumen expansion.

Conclusions:

• The identified mechanisms of epithelial thinning and mitotic cell contraction are key regulators of lumen growth and shape in the developing inner ear.
• These findings provide new insights into the interplay between cellular behaviors, tissue mechanics, and organ morphogenesis.
• Understanding these processes is critical for comprehending the etiology of congenital diseases linked to abnormal organ development.