Intestinal intermediate filament polypeptides in C. elegans: Common and isotype-specific contributions to intestinal...

Area of Science:

• Cell Biology
• Biophysics
• Developmental Biology

Background:

• Intermediate filaments (IFs) are abundant in the C. elegans intestine, suggesting vital roles in intestinal function and organismal health.
• IFs localize below the actin brush border and are enriched in the endotube, a structure enveloping the intestinal lumen and attached to the apical junction.

Purpose of the Study:

• To investigate the mechanical properties and structural contributions of intestinal intermediate filaments in C. elegans.
• To determine the specific roles of different IFs in maintaining intestinal structure and function.

Main Methods:

• Brillouin microscopy was used to map intestinal viscoelasticity, revealing the endotube's position at the interface of the brush border and cytoplasm.
• Loss-of-function mutants for various IFs (IFB-2, IFC-2, IFD-2, IFC-1, IFD-1, IFP-1) were analyzed using ultrastructural and phenotypic assessments.

Main Results:

• The IF-rich endotube is positioned to buffer mechanical stress from luminal distortions.
• Depletion of IFB-2, IFC-2, and IFD-2 resulted in intestinal lumen dilation, with IFB-2 and IFC-2 mutants showing significant endotube defects (rarefaction or absence).
• While most IF-deficient mutants reached adulthood, they exhibited developmental delays, reduced brood size, and increased sensitivity to various stresses.

Conclusions:

• Individual intestinal IF polypeptides play distinct roles in endotube morphogenesis.
• Cooperative action of IFs is essential for coping with environmental changes and maintaining intestinal homeostasis.