Abstract
Purpose :
The embryonic tissues that contribute to the trabecular meshwork (TM) and Schlemm's canal (SC) include the periocular mesenchyme, which is derived from the cranial neural crest cells (NCCs). We have previously shown that conditional deletion of AP-2β transcription factor in NCC in mice using two different Cre drivers (Wnt1-Cre and MgpCre) results in anterior segment dysgenesis (ASD) in the mutants (AP-2β TMR KO and AP-2β NCC KO mice, respectively), including iridocorneal adhesions, TM and SC defects, raised intraocular pressure (IOP) and subsequent retinal ganglion cell degeneration.
Methods :
The AP-2β TMR KO and AP-2β NCC KO mice will be generated as done previously and will be further investigated to determine the advantages of each in studying ASD and glaucoma. We further leverage the AP-2β NCC KO model as a means to identify the critical AP-2β-dependent gene regulatory mechanisms responsible for the observed defects, using scRNA-Seq.
Results :
Our findings revealed that both the AP-2β TMR KO and AP-2β NCC KO models exhibit an underdeveloped trabecular meshwork (TM) and absent Schlemm’s canal (SC), and elevated IOP by postnatal day 30. Interestingly, in the AP-2β TMR KO mice the iris is no longer adhered along its whole length to the cornea as observed in the AP-2β NCC KOs. These findings have important implications for the unconventional outflow pathway that was found to be operational in the AP-2β TMR KO mice but not the AP-2β NCC KOs. ScRNAseq analysis of the anterior segment of P7 AP-2β NCC KO and wild-type samples revealed several important findings concerning not only differences in cell populations but also gene expression patterns that are disrupted by loss of AP-2β. For example, significant changes in the angle include a down-regulation in Hs3st3a1, a gene involved in heparin sulfate synthesis, as well as in the corneal stroma where there is a switch in the expression of various collagen genes.
Conclusions :
Both the AP-2β TMR KO and AP-2β NCC KO models offer advantages for understanding the role of AP-2β in regulating anterior segment development and for studying developmental glaucoma. Our ongoing studies will further use single cell multiome approaches to correlate changes in gene expression to alterations in chromatin accessibility in the presence or absence of Tfap2b to identify important target genes for this transcription factor in the anterior segment.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.