Abstract
Purpose: :
In Drosophila, studies have shown that PDZ proteins Dlg-1 and Scrib are important regulators of cell proliferation, adhesion and polarity. Previous work in our laboratory using PDZ deficient mouse models has demonstrated a role for PDZ proteins in cell cycle regulation and fiber cell differentiation in lens development. In this report, we asked if Dlg-1 and Scrib play a role or roles in the epithelium.
Methods: :
Mice carrying Dlg-1 or Scrib conditional allele were crossed with MLR10cre transgenic mice. Eyes from Dlg-1cko, Scribcko and control progeny were embedded in paraffin, sectioned and stained with hematoxylin and eosin (H&E) to assess lens morphology. Immunohistochemistry for Cyclin D1 (G1 phase), phosphohistone H3 (M phase) and BrdU (S phase) was used to assess effects on the cell cycle. TUNEL was carried out to assess apoptosis. To examine the cell adhesion, double immunostaining for E-cadherin and -catenin was performed. To assess cell polarity sections were immunostained for ZO-1.
Results: :
By H&E staining, when compared to controls, the epithelium of the Dlg-1cko lenses appeared disorganized, with pockets of multilayering, and the total number of cells was greater than normal, suggesting defects in cell cycle regulation. Further analysis, showed that the percent BrdU+ and percent cyclinD1+ cells in Dlg-1cko lenses was less than in control lenses while the percent phosphohistoneH3+ cells was similar between Dlg-1cko and control lenses. The epithelium in Scribcko lenses also was disorganized with areasof multilayering. The total number of cells and percent BrdU+ cells in control and Scribcko were similar. However, Scribcko lenses showed BrdU+ cells in the transition zone, which was not seen Dlg-1cko lenses. E-cadherin staining was highly associated with the apical and basal membranes of the epithelial cells in control lenses. In contrast, in Dlg-1cko lenses E-cadherin staining was diffuse along all membrane surfaces. In Scribcko lenses, E-cadherin appeared to be lost from the basal membrane. Finally, in control lenses, ZO-1 staining was observed only on the apical surface of epithelial cells. In contrast, in Dlg-1cko lenses ZO-1 was observed along the basal and lateral surfaces in the central epithelium. Localization of ZO-1 in the epithelium of Scribcko lenses was similar to that in controls.
Keywords: immunohistochemistry • wound healing