Abstract
Purpose :
Brittle cornea syndrome (BCS) is a rare connective tissue disease in which the structure of the cornea is particularly compromised. Patients present severe visual impairments from a young age associated with the abnormally thin cornea, and are at high risk of irreversible sight loss due to corneal rupturing. BCS is caused by mutations in one of two genes ZNF469 and PRDM5. Our lab has previously published the first mouse model of BCS, carrying a mutation within the ZNF469 mouse orthologue Zfp469, showing that it perfectly recapitulates the human disease with a thinner and structurally compromised cornea. TEM analysis showed that the collagen fibrils, which make up most of the structurally dense stroma, had a significantly thinner diameter in mutants compared to wild type littermates. We hope to use this model to better elucidate the cellular mechanisms underpinning this disease and their developmental timing.
Methods :
Using this mouse model we have looked at the developing cornea to assess where, when and how abundantly key genes, including Zfp469, are expressed. RNAscope allows us to visualise transcript levels of lowly expressed genes so we are able to have a direct readout of Zfp469 transcription in the developing cornea. Immunohistochemistry on these same stages of corneal development were performed to visualise collagen deposition as the stroma becomes the organised tissue required for a functional cornea. We have also performed single cell RNAseq on juvenile mouse corneas with BCS and their wild type littermates to investigate differences in gene expression and cell populations in the postnatal cornea.
Results :
RNAscope and immunohistochemical analysis of key embryonic stages of corneal development showed a wave of expression of Zfp469 in stromal cells, correlating to the production and deposition of primary fibrillar collagens, supporting a key role in this process. Single cell RNAseq highlighted differences in gene expression and cell populations between BCS corneas and their wild type litter mates; these differences being direct or indirect consequences of Zfp469 loss of function remains to be elucidated.
Conclusions :
This work is essential to the better understanding of the development of BCS, which is itself an integral part of developing therapies to treat and alleviate symptoms. With the continued investigation of our disease model we hope to benefit the patients suffering from it.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.