Periocular Mesenchyme (POM) Contributes to Anterior Eye Structures

Abstract

PurposeEstablish a new glaucoma animal model. The objective of this project is to determine if Gli1 positive cells contribute to the POM and anterior eye structures by using inducible Gli1‐CreERT2; tdTomatoflox (Gli1‐tdTomato) mouse model to serve as a probe for anterior eye development. Pitx2, FOXC1, and FOXC2 are expressed in the periocular mesenchyme, and are critical for anterior eye development. Mutations in these genes are associated with a broad spectrum of abnormalities in these tissues. A second objective is to establish that FOXC1, FOXC2, and Pitx2 are expressed in the Gli1 positive cells.MethodsGli1‐tdTomato expressing mice were induced at different stages with tamoxifen. Eyes were examined that were induced on embryonic (E13.5) and postnatal days: P3, P7, 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.ResultsIn Gli1‐tdTomato mice induced on P3, P7, and P30, the POM and anterior angle of the eye, eyelids and optic nerve were labeled 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 postnatal ages. After postnatal day 30, the expression decreased with little to no expression of FOXC1 and FOXC2 while Pitx2 expression remained relatively constant in the anterior angle tissues and was expressed in some Gli1 positive cells.ConclusionThis inducible Gli1‐tdTomato mouse model may be an excellent system for determining the role of POM 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 and other detection probes (phalloidin, nuclear stains, Immunohistochemistry etc), can be incorporated to determine cell characteristics or over‐all tissue structure. Our results provide evidence that POM cells are contributing to the development of the anterior angle chamber that forms between P3‐P10 in mice.Support or Funding InformationBiomedical Sciences Department Seed Grant (K. Svoboda), NIH K08DE025090 (H. Zhao)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.