Conditional deletion of AP-2β in the cranial neural crest results in anterior segment dysgenesis and early-onset glaucoma

Abstract

Anterior segment dysgenesis (ASD) encompasses a group of developmental disorders in which a closed angle phenotype in the anterior chamber of the eye can occur and 50% of patients develop glaucoma. Many ASDs are thought to involve an inappropriate patterning and migration of the periocular mesenchyme (POM), which is derived from cranial neural crest cells (NCC) and mesoderm. Although, the mechanism of this disruption is not well understood a number of transcriptional regulatory molecules have previously been implicated in ASDs. Here we investigate the function of the transcription factor AP-2β, encoded by Tfap2b, which is expressed in the NCC and its derivatives. Wnt1-Cre mediated conditional deletion of Tfap2b in NCC resulted in postnatal ocular defects typified by opacity. Histological data revealed that the conditional AP-2β NCC knockout mutants exhibited dysgenesis of multiple structures in the anterior segment of the eye including defects in the corneal endothelium, corneal stroma, ciliary body and disruption in the iridocorneal angle with adherence of the iris to the cornea. We further show that this phenotype leads to a significant increase in intraocular pressure and a subsequent loss of retinal ganglion cells and optic nerve degeneration, features indicative of glaucoma. Overall, our findings demonstrate that AP-2β is required in the POM for normal development of the anterior segment of the eye and that the AP-2β NCC KO mice may serve as a new and exciting model of ASD and glaucoma that is fully penetrant and with early post-natal onset.