Apical constriction and epithelial invagination are regulated by BMP activity

Area of Science:

• Developmental Biology
• Cell Biology
• Molecular Biology

Background:

• Epithelial invagination is a key developmental process involving tissue bending and apical constriction.
• While intracellular mechanisms are known, extracellular signals regulating invagination remain understudied.

Purpose of the Study:

• To investigate the role of the extracellular signal Bone Morphogenetic Protein (BMP) in epithelial invagination.
• To determine if BMP regulates processes like apical constriction and cell elongation during placodal invagination.

Main Methods:

• Established in vivo assays for placodal invagination.
• Inhibited BMP activity in prospective cranial placodes.
• Analyzed RhoA and F-actin rearrangements, apical constriction, cell elongation, cell death, and proliferation.

Main Results:

• BMP signaling is essential for RhoA and F-actin rearrangements, apical constriction, cell elongation, and epithelial invagination.
• BMP inhibition disrupts apical accumulation of RhoA and F-actin, leading to failed invagination.
• Epithelial invagination and placode-specific identity acquisition are distinct developmental processes.

Conclusions:

• BMP signals act upstream of intracellular machinery to promote epithelial invagination.
• BMP is required for apical constriction and cell elongation during this process.
• This study elucidates the extracellular regulation of epithelial morphogenesis.