Proteasomal Dysfunction results in ER stress, Endo MT, oxidative stress, and apoptotic cell death resulting in Fuchs Corneal Endothelial Dystrophy like features in mice

Abstract

Fuchs Endothelial Corneal Dystrophy (FECD) is the irreversible degeneration of the corneal endothelium. The only treatment is corneal transplantation. To develop therapies for FECD, identifying the cellular causes for the onset and progression of the disease is crucial. While cell culture studies associate elevated oxidative stress, endoplasmic reticulum stress, endothelial-to-mesenchymal transition, and apoptosis with FECD, the causes behind the disease onset remain elusive. Guttae or Descemets membrane deposits are the earliest phenotype associated with FECD and are composed of unfolded proteins. Therefore, we asked if aberrant protein clearance pathways could be responsible for disease pathogenesis. We discovered a dysfunctional ubiquitin-proteasome pathway in a FECD mouse model and end-stage FECD patient samples. Inhibiting the ubiquitin-proteasome pathway in primary corneal endothelial cells resulted in the cellular dysfunctions associated with FECD. Finally, injecting healthy wild-type mice with proteasomal inhibitors resulted in all the major phenotypes associated with FECD, including corneal edema, guttae, and corneal endothelial cell loss. Therefore, this study strongly connects proteasomal dysfunction in FECD onset and progression.