PAX6, modified by SUMOylation, plays a protective role in corneal endothelial injury

Abstract

Treating corneal endothelial diseases tends to be challenging as human corneal endothelial cells (CECs) do not proliferate in vivo. The pathogenesis or mechanisms underlying injured CECs need further studies. The abnormal expression of PAX6, which is an essential transcription factor for corneal homeostasis, exhibits corneal endothelial defects. However, the effects of PAX6 protein involved in corneal endothelial wound process are still unknown. Here, we found the upregulated protein levels of PAX6 in human corneal endothelial monolayer after injury; the expression of PAX6 also increased in murine and rat corneal endothelium injury models. Enforced PAX6 expression could alleviate the damages to CECs via regulating permeability by prompting cellular tight junction. In addition, SUMOylation mainly happened on both K53 and K89 residues of 48-kD PAX6 (the longest and main isoform expressed in cornea), and de-SUMOylation promoted the stability of PAX6 protein in vitro. In CECs of SENP1 +/− mice, increased SUMOylation levels leading to instability and low expression of PAX6, delayed the repair of CECs after injury. Furthermore, overexpression of PAX6 accelerated the rate of corneal endothelial repair of SENP1 +/− mice. Our findings indicate that SENP1mediated de-SUMOylation improving the stability of PAX6, amplifies the protective effects of PAX6 on corneal endothelial injuries, highlighting potentials of PAX6 and/or SUMOylation to be used as a treatment target for corneal endothelial disorders.

End binding-3 inhibitor activates regenerative program in age-related macular degeneration

“…However, the expression level of these proteins in the retinal tissue was unaffected ( Figures S7 J and S7K). Consistent with the proposed role of PAX6 in upregulating the expression of junctional proteins, 71 we observed increased expression of N-cadherin ( CDH2 ) and CDH23 in metabolic-active ECs (cluster 4; Figure S6 D) of NHPs treated with Myr-EBIN. Additionally, our results showed that Myr-EBIN upregulated VE-cadherin in mature ECs (cluster 19; Figure S6 D).…”

“…From this perspective, EBIN shows therapeutic potential to promote this developmental program through the epigenetic regulation of the promoter regions of MEIS2 and PAX6 genes, the key TFs involved in retinal development. 76 Consistent with the proposed protective role of PAX6 in corneal endothelial injury through the increased expression of junctional proteins, 71 our data demonstrate upregulation of N-cadherin ( Cdh2 gene), which promotes the recruitment of VE-cadherin to AJs, 77 in metabolic-active ECs after EBIN treatment. EBIN also induces the expression of MEIS2, which not only functions as a co-factor of PAX6 78 but transcriptionally activates PAX6 expression through binding to its enhancer.…”

Restoration of functional PAX6 in aniridia patient iPSC-derived ocular tissue models using repurposed nonsense suppression drugs

“… 44 In addition, previous studies have shown that NMD efficiency varies between different murine tissues, 45 but in the choroideremia study, no significant difference in CHM mRNA levels were seen between two different patients’ fibroblast lines and their corresponding iPSC-derived RPE. 44 The nonsense variants described in this study do result in loss of function, and we therefore hypothesize that other mechanisms could contribute to PAX6 haploinsufficiency, such as post-translational modifications or epigenetic regulations of the protein; 46 , 47 this requires further investigation.…”

Multi-System-Level Analysis with RNA-Seq on Pterygium Inflammation Discovers Association between Inflammatory Responses, Oxidative Stress, and Oxidative Phosphorylation

“…For instance, (i) Il36g (IL-36γ), one of the pro-inflammatory agonists expressed by the corneal epithelium, was reported to be upregulated following corneal injury and was observed to be remarkably upregulated in our Asian pterygiums [9]. (ii) The expression of PAX6 was considerably downregulated in corneal epithelial cells isolated from patients with severe ocular surface inflammatory diseases such as Stevens-Johnson Syndrome or recurrent pterygiums [10]. (iii) Considering the impairment of autophagy as a potential cause of pterygiums, we observed that MALAT1, a long non-coding RNA that promotes autophagy in retinoblastoma cells, was markedly downregulated in the European pterygiums [11].…”