title: Keratin 12 missense mutation induces the unfolded protein response and apoptosis in Meesmann epithelial corneal dystrophy.
abstract: Meesmann epithelial corneal dystrophy (MECD) is a rare autosomal dominant disorder caused by dominant-negative mutations within the KRT3 or KRT12 genes, which encode the cytoskeletal protein keratins K3 and K12, respectively. To investigate the pathomechanism of this disease, we generated and phenotypically characterized a novel knock-in humanized mouse model carrying the severe, MECD-associated, K12-Leu132Pro mutation. Although no overt changes in corneal opacity were detected by slit-lamp examination, the corneas of homozygous mutant mice exhibited histological and ultrastructural epithelial cell fragility phenotypes. An altered keratin expression profile was observed in the cornea of mutant mice, confirmed by western blot, RNA-seq and quantitative real-time polymerase chain reaction. Mass spectrometry (MS) and immunohistochemistry demonstrated a similarly altered keratin profile in corneal tissue from a K12-Leu132Pro MECD patient. The K12-Leu132Pro mutation results in cytoplasmic keratin aggregates. RNA-seq analysis revealed increased chaperone gene expression, and apoptotic unfolded protein response (UPR) markers, CHOP and Caspase 12, were also increased in the MECD mice. Corneal epithelial cell apoptosis was increased 17-fold in the mutant cornea, compared with the wild-type (P < 0.001). This elevation of UPR marker expression was also observed in the human MECD cornea. This is the first reporting of a mouse model for MECD that recapitulates the human disease and is a valuable resource in understanding the pathomechanism of the disease. Although the most severe phenotype is observed in the homozygous mice, this model will still provide a test-bed for therapies not only for corneal dystrophies but also for other keratinopathies caused by similar mutations.
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, Northern Ireland, UK, Centre for Dermatology and Genetic Medicine, Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Scotland DD1 5EH, UK.
authors.forename: Edwin H A
authors.initials: EH
authors.lastname: Allen
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, Northern Ireland, UK.
authors.forename: David G
authors.initials: DG
authors.lastname: Courtney
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, Northern Ireland, UK.
authors.forename: Sarah D
authors.initials: SD
authors.lastname: Atkinson
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, Northern Ireland, UK, Cathedral Eye Clinic, Academy Street, Belfast BT15 1ED, UK.
authors.forename: Johnny E
authors.initials: JE
authors.lastname: Moore
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, Northern Ireland, UK.
authors.forename: Laura
authors.initials: L
authors.lastname: Mairs
authors.affiliation: Department of Molecular Biology and Genetics.
authors.forename: Ebbe Toftgaard
authors.initials: ET
authors.lastname: Poulsen
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, Northern Ireland, UK.
authors.forename: Davide
authors.initials: D
authors.lastname: Schiroli
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, Northern Ireland, UK.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Maurizi
authors.affiliation: Centre for Dermatology and Genetic Medicine, Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Scotland DD1 5EH, UK.
authors.forename: Christian
authors.initials: C
authors.lastname: Cole
authors.affiliation: Centre for Dermatology and Genetic Medicine, Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Scotland DD1 5EH, UK.
authors.forename: Robyn P
authors.initials: RP
authors.lastname: Hickerson
authors.affiliation: Microscopy Facility, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
authors.forename: John
authors.initials: J
authors.lastname: James
authors.affiliation: Department of Ophthalmology, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK.
authors.forename: Helen
authors.initials: H
authors.lastname: Murgatroyd
authors.affiliation: Centre for Dermatology and Genetic Medicine, Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Scotland DD1 5EH, UK.
authors.forename: Frances J D
authors.initials: FJ
authors.lastname: Smith
authors.affiliation: Department of Ophthalmology, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK.
authors.forename: Carrie
authors.initials: C
authors.lastname: MacEwen
authors.affiliation: Department of Molecular Biology and Genetics, Interdisciplinary Nanoscience Center (iNANO) and Center for Insoluble Protein Structures (inSPIN), Science Park, Aarhus University, Aarhus, Denmark and.
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Enghild
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, Northern Ireland, UK.
authors.forename: M Andrew
authors.initials: MA
authors.lastname: Nesbit
authors.affiliation: Centre for Dermatology and Genetic Medicine, Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Scotland DD1 5EH, UK.
authors.forename: Deena M
authors.initials: DM
authors.lastname: Leslie Pedrioli
authors.affiliation: Centre for Dermatology and Genetic Medicine, Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Scotland DD1 5EH, UK, t.moore@ulster.ac.uk w.h.i.mclean@dundee.ac.uk.
authors.forename: W H Irwin
authors.initials: WH
authors.lastname: McLean
authors.affiliation: School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, Northern Ireland, UK, t.moore@ulster.ac.uk w.h.i.mclean@dundee.ac.uk.
authors.forename: C B Tara
authors.initials: CB
authors.lastname: Moore
mesh_terms: D000328:Adult; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D053559:Corneal Dystrophy, Juvenile Epithelial of Meesmann / Q000235:genetics*; D004195:Disease Models, Animal; D005091:Exons; D005260:Female; D006579:Heterozygote; D006801:Humans; D053551:Keratin-12 / Q000235:genetics*; D053558:Keratin-3 / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D020125:Mutation, Missense; D010375:Pedigree; D056811:Unfolded Protein Response
chemical_list: C507494:KRT12 protein, human; C479360:KRT3 protein, human; D053551:Keratin-12; D053558:Keratin-3