Abstract
Purpose: :
In invertebrates like D. melanogaster, the PDZ protein Scribble is a regulator of cell polarity, proliferation, and adhesion. Prior studies in our laboratory suggested that certain PDZ proteins, including Scribble, might play a role in regulating cell proliferation, polarity and adhesion in the mouse lens. Our preliminary analysis of lenses in Scrib null mice suggests that Scrib assists in regulating epithelial cell proliferation and fiber cell differentiation. To further define the roles that Scrib plays in lens development, we generated mice in which Scrib was deleted specifically in the lens fiber cells and compared these lens phenotypes to that of Scrib null mice.
Methods: :
Mice carrying a conditional null allele of Scrib were crossed to MLR39cre transgenic mice. Eyes from neonatal Scribf/f and Scribf/f;cre were embedded in paraffin and oriented longitudinally. Sections were stained with hematoxylin and eosin (H&E) and propidium iodide (PI) to assess lens histology. BrdU and TUNEL were used to assess proliferation and apoptosis, respectively. To examine cell adhesion, sections were double immunostained for N-cadherin and α-catenin and viewed by confocal microscopy. Finally, eye cryosections were stained with phalloidin to assess the organization of filamentous actin.
Results: :
Scribf/f;cre lenses were often smaller than controls. Scribf/f;cre fibers were vacuolated and did not have the normal concave curvature. Suture defects were apparent and PI staining showed that nuclei were misoriented. TUNEL positive nuclei were observed in cortical lens fibers, which normally are TUNEL negative. N-cadherin and α-catenin colocalization was reduced along the posterior tips and lateral membranes of fibers. Analysis of unmerged images suggested that this observation may be due to reduced staining of N-cadherin and α-catenin along the lateral membranes and reduced staining of N-cadherin at the posterior tips. Phalloidin staining showed abnormal aggregations of filamentous actin and reduced staining in the apical portions of the fibers.
Keywords: development • cell adhesions/cell junctions