Abstract
Purpose :
The objective of this project is to determine if Gli1 positive cells contribute to the trabecular meshwork by using an inducible Gli1-CreERT2; tdTomatoflox (Gli1-tdTomato) mouse model. This investigation builds on and expands our previous report on Gli1 positive cells in the periocular mesoderm. Mutations in Pitx2, FOXC1, and FOXC2 have been associated with a broad spectrum of abnormalities in anterior eye tissues. A second objective was to establish if FOXC1, FOXC2, and Pitx2 were expressed in the Gli1 positive cells.
Methods :
Gli1-tdTomato expressing mice were induced at different stages with tamoxifen. Eyes were examined that were induced on various embryonic and post-natal days, P3, P7, and P30 and sacrificed several days to weeks later. Mouse tissues were fixed and prepared for frozen or paraffin sectioning. Tissue antigen retrieval was done using citric acid buffer. Indirect immunohistochemistry for FOXC1, FOXC2, and Pitx2 was completed. Some samples were counterstained with phalloidin. Sections were analyzed with confocal microscopy for spatial distribution of the Gli1+ labeled cells and FOXC1, FOXC2, and Pitx2.
Results :
In Gli1-tdTomato mice induced on P3, P7, and P30, the POM and anterior angle of the eye, eyelids and optic nerve were examined several days to 3 weeks later. In contrast, the cornea, lens and sclera did not have positive cells for Gli1. Expression levels for FOXC1, FOXC2, and Pitx2 were generally higher in mice harvested at younger ages. After postnatal day 30, the expression decreased with little to no expression of FOXC1 and FOXC2 while Pitx2 expression remained relatively constant in anterior angle tissues.
Conclusions :
This inducible Gli1-tdTomato mouse model may be an excellent system for determining the role of Gli1 positive cells in anterior eye development. The elegance of this model is it can be activated at specific developmental stages and Gli1+ cell derivatives can be tracked for months. Our results provide evidence that Gli1+ cells are contributing to the development of the anterior angle tissues including the trabecular meshwork P3-P51 in mice.
This is a 2020 ARVO Annual Meeting abstract.