Localization of apical epithelial determinants by the basolateral PDZ protein Scribble

Area of Science:

• Cell Biology
• Developmental Biology
• Epithelial Biology

Background:

• Cell polarization involves creating distinct membrane domains with specific protein compositions.
• Epithelial cells segregate membrane proteins into apical and basolateral compartments, crucial for tissue function and signaling.
• Mechanisms restricting apical determinants to the apical surface in Drosophila epithelia remain unclear.

Purpose of the Study:

• To investigate the role of laterally localized proteins in confining apical polarity determinants.
• To elucidate the function of Drosophila scribble (scrib) in epithelial cell organization and polarity.

Main Methods:

• Genetic analysis of Drosophila scribble (scrib) mutants.
• Immunolocalization studies to assess protein distribution in wild-type and mutant epithelia.
• Analysis of cell morphology and epithelial monolayer organization.

Main Results:

• Mutations in scrib lead to aberrant cell shapes and loss of epithelial monolayer organization.
• Scrib protein localizes to the septate junction, separating apical and basolateral domains.
• Loss of scrib function causes mislocalization of apical proteins and adherens junctions to the basolateral surface.
• Basolateral protein localization remains unaffected in scrib mutants.

Conclusions:

• The lateral epithelial domain, specifically the septate junction, plays a critical role in restricting apical membrane identity.
• Scrib protein is essential for maintaining epithelial polarity by confining apical determinants.
• Correct placement of adherens junctions depends on scrib function and septate junction integrity.