Cataracts and Microphthalmia Caused by a Gja8 Mutation in Extracellular Loop 2
Figure 4
Confocal imaging of GFP-positive (GFP+) live lenses from wild-type (WT), Gja8 knockout (Gja8−/−), Gja8R205G homozygous mutant (Gja8R205G/R205G) and Gja8R205G Gja3 double mutant (Gja8R205G/R205G Gja3−/−) mice at the age of 2
weeks. (A) Confocal images showed the typical mosaic pattern of GFP in lens central epithelial cells in all lenses examined. Aberrant epithelial cells appeared only in the Gja8R205G/R205G lens. (B) Images displayed the anterior Y-suture (delineated by the white lines in the WT lens) where the ends of underlying fiber cells come into contact. These elongated fiber cells in the WT lens had normal uniform GFP signal. There was a partial delay in Y-suture closure in the Gja8−/− lens. In the Gja8R205G/R205G mutant lens, aberrant GFP+ cells were observed in the open suture region where the opposing fiber cells failed to elongate fully to close the anterior Y-suture. The Gja8R205G/R205G Gja3−/− double mutant lens also had an open suture (black area) due to insufficient fiber cell elongation. (C) An anterior (top) to posterior (bottom) sectional view from three-dimensional z-stack reconstructions of GFP+ lenses showing the lens equator (indicated by an arrow) and peripheral fiber cells. Only Gja8R205G/R205G homozygous lenses displayed disorganized fiber cells. Scale bars, 50 μm. (D) A cross sectional view from three-dimensional reconstructions of z-stacks of GFP+ lenses at the lens equator. Lens epithelial cells are on the left. In the WT lens, peripheral fiber cells were precisely organized and displayed a mosaic GFP expression pattern while inner fiber cells showed uniform GFP signal. In the Gja8−/− lens, peripheral fiber cells remained organized. In the Gja8R205G/R205G homozygous mutant lenses, peripheral fiber cells were completely disorganized with vacuole-like structures or enlarged extracellular spaces (indicated by an asterisk). However, in Gja8R205G/R205G Gja3−/− double mutant lenses, peripheral fiber cells were mainly organized.