L450W and Q455KCol8a2Knock-In Mouse Models of Fuchs Endothelial Corneal Dystrophy Show Distinct Phenotypes and Evidence for Altered Autophagy

Abstract

PURPOSE. We compared the cellular phenotypes and studied the role of autophagy in the pathogenesis of Fuchs endothelial corneal dystrophy (FECD) using two a2 collagen VIII (Col8a2) knock-in mouse models and human FECD tissues. METHODS.In vivo corneal endothelial cell (CEC) counts and morphology were analyzed by clinical confocal microscopy. Ultrastructural analysis of CECs was performed by transmission electron microscopy. Real-time PCR and Western blotting were performed using total RNA, and protein extracted from mouse CECs and human CECs obtained from FECD and autopsy patients.RESULTS. Both Col8a2 mouse models exhibited hallmarks of FECD; however, the Col8a2 L450W/L450W mice exhibited a milder phenotype compared to the Col8a2 Q455K/Q455K mice. Both models exhibited upregulation of the unfolded protein response (UPR) as evidenced by dilated rough endoplasmic reticulum (RER), and upregulation of UPR-associated genes and proteins. Real-time PCR of Col8a2 L450W/L450W and Col8a2 Q455K/Q455K CECs at 40 weeks revealed a 2.1-fold (P < 0.05) and a 5.2-fold (P < 0.01) upregulation of the autophagy marker Dram1, respectively. Real-time PCR of human FECD endothelium revealed a 10.4-fold upregulation of DRAM1 (P < 0.0001) compared to autopsy controls. CONCLUSIONS. The Col8a2L450W/L450W and Col8a2

Restoration of Mitochondrial Integrity, Telomere Length, and Sensitivity to Oxidation by In Vitro Culture of Fuchs' Endothelial Corneal Dystrophy Cells

“…of FECD (Col8a2 knock-in). 40 In the present study, we documented increased levels of mitochondria and mtDNA content in FECD explants (Fig. 1), two parameters that usually correlate.…”

The pathophysiology of Fuchs' endothelial dystrophy – A review of molecular and cellular insights

“…Type VIII collagen is an important part of Descemet's Membrane (DM) secreted by the endothelium (Shuttleworth, 1997). Homozygous knock-in mouse models containing one of the two mutations demonstrate early onset FECD pathology Meng et al, 2013); currently these are the only mouse models that display consistent FECD pathology. On the other hand, mice deficient in a1 and a2 subunits of collagen VIII exhibit reduced endothelial numbers with polymegathism and polymorphism, corneal opacification, and a thin DM despite absence of guttae, therefore the effects of collagen VIII deficiency are not the same as that caused by COL8A2 mutations (Hopfer et al, 2005).…”

The Genetics and Pathophysiology of IC3D Category 1 Corneal Dystrophies

“…86 Two genetic knock-in mice have successfully recapitulated human FECD by introducing the previously identified Q455K and L450W mutations in COL8A2. 87, 88 In these mouse models, there is evidence to support a link between the COL8A2 mutations and UPR-mediated autophagy (cell death): enlarged rough ER were observed alongside up-regulation of UPR genes and proteins, including damage-regulated autophagy modulator (DRAM1).…”