Direct visualization of epithelial microvilli biogenesis

Area of Science:

• Cell Biology
• Epithelial Biology
• Cytoskeleton Dynamics

Background:

• Microvilli are crucial actin-bundle-supported protrusions in epithelial cells, vital for various functions.
• Understanding microvilli biogenesis is key to comprehending epithelial cell specialization and function.

Purpose of the Study:

• To elucidate the dynamic process of microvillus biogenesis using live imaging.
• To identify specific molecular factors involved in the initiation and regulation of microvillus formation.

Main Methods:

• Live imaging and time-lapse microscopy were employed to observe early stages of epithelial differentiation.
• Tracking of specific protein localization, including epidermal growth factor pathway substrate 8 (EPS8) and insulin-receptor tyrosine kinase substrate (IRTKS) (BAIAP2L1), at the cell surface.

Main Results:

• Epidermal growth factor pathway substrate 8 (EPS8) and insulin-receptor tyrosine kinase substrate (IRTKS) mark sites of future microvillus growth.
• Actin bundle elongation, ezrin recruitment, and membrane encapsulation were observed sequentially during de novo growth.
• New microvilli can arise from existing protrusions, and nascent microvilli can collapse through a defined sequence of molecular events.

Conclusions:

• This study provides the first temporally resolved mechanism for microvillus growth.
• Identified key factors (EPS8, IRTKS, ezrin) and processes governing microvillus biogenesis.
• Insights into apical specialization growth mechanisms applicable to diverse epithelial contexts.