Meisosomes, folded membrane microdomains between the apical extracellular matrix and epidermis

Area of Science:

• Cell biology
• Biophysics
• Developmental biology

Background:

• Apical extracellular matrices (aECMs) provide a crucial physical barrier.
• The nematode cuticle, an epidermal aECM, comprises collagens forming ridges and furrows.
• Epidermal connections to the cuticle are vital for skin integrity.

Purpose of the Study:

• Investigate the role of epidermal furrows in maintaining the connection between the epidermis and the cuticle.
• Characterize novel ultrastructural components in mutants lacking epidermal furrows.
• Explore the function of these structures in biomechanical signaling and damage response.

Main Methods:

• Electron microscopy to analyze ultrastructure in wild-type and mutant Caenorhabditis elegans.
• Biomechanical property assessment of mutant skin.
• Localization studies for phosphatidylinositol (4,5) bisphosphate.

Main Results:

• Mutants lacking furrows exhibit a loss of epidermal-cuticle connection, particularly at the lateral epidermis.
• Novel structures, termed meisosomes (stacked plasma membrane folds filled with cuticle), are identified.
• Meisosomes are associated with phosphatidylinositol (4,5) bisphosphate-enriched domains and may function in signal transduction.

Conclusions:

• Meisosomes are proposed to connect the lateral epidermis to the cuticle, analogous to hemidesmosomes elsewhere.
• Furrow mutants show altered skin biomechanics and constitutive epidermal damage response.
• Meisosomes may serve as signaling platforms relaying mechanical stress from the aECM to the epidermis.