title: Targeted proteolysis of plectin isoform 1a accounts for hemidesmosome dysfunction in mice mimicking the dominant skin blistering disease EBS-Ogna.
abstract: Autosomal recessive mutations in the cytolinker protein plectin account for the multisystem disorders epidermolysis bullosa simplex (EBS) associated with muscular dystrophy (EBS-MD), pyloric atresia (EBS-PA), and congenital myasthenia (EBS-CMS). In contrast, a dominant missense mutation leads to the disease EBS-Ogna, manifesting exclusively as skin fragility. We have exploited this trait to study the molecular basis of hemidesmosome failure in EBS-Ogna and to reveal the contribution of plectin to hemidesmosome homeostasis. We generated EBS-Ogna knock-in mice mimicking the human phenotype and show that blistering reflects insufficient protein levels of the hemidesmosome-associated plectin isoform 1a. We found that plectin 1a, in contrast to plectin 1c, the major isoform expressed in epidermal keratinocytes, is proteolytically degraded, supporting the notion that degradation of hemidesmosome-anchored plectin is spatially controlled. Using recombinant proteins, we show that the mutation renders plectin's 190-nm-long coiled-coil rod domain more vulnerable to cleavage by calpains and other proteases activated in the epidermis but not in skeletal muscle. Accordingly, treatment of cultured EBS-Ogna keratinocytes as well as of EBS-Ogna mouse skin with calpain inhibitors resulted in increased plectin 1a protein expression levels. Moreover, we report that plectin's rod domain forms dimeric structures that can further associate laterally into remarkably stable (paracrystalline) polymers. We propose focal self-association of plectin molecules as a novel mechanism contributing to hemidesmosome homeostasis and stabilization.
authors.affiliation: Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, Centre for Molecular Biology, University of Vienna, Vienna, Austria.
authors.forename: Gernot
authors.initials: G
authors.lastname: Walko
authors.forename: Nevena
authors.initials: N
authors.lastname: Vukasinovic
authors.forename: Karin
authors.initials: K
authors.lastname: Gross
authors.forename: Irmgard
authors.initials: I
authors.lastname: Fischer
authors.forename: Sabrina
authors.initials: S
authors.lastname: Sibitz
authors.forename: Peter
authors.initials: P
authors.lastname: Fuchs
authors.forename: Siegfried
authors.initials: S
authors.lastname: Reipert
authors.forename: Ute
authors.initials: U
authors.lastname: Jungwirth
authors.forename: Walter
authors.initials: W
authors.lastname: Berger
authors.forename: Ulrich
authors.initials: U
authors.lastname: Salzer
authors.forename: Oliviero
authors.initials: O
authors.lastname: Carugo
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Castañón
authors.forename: Gerhard
authors.initials: G
authors.lastname: Wiche
mesh_terms: D000818:Animals; D001768:Blister / Q000235:genetics*; D002154:Calpain / Q000037:antagonists & inhibitors / Q000187:drug effects; D004151:Dipeptides / Q000494:pharmacology; D004195:Disease Models, Animal; D000078404:Epidermal Cells; D004817:Epidermis / Q000378:metabolism / Q000648:ultrastructure; D016110:Epidermolysis Bullosa Simplex / Q000235:genetics*; D015870:Gene Expression; D055879:Gene Knock-In Techniques; D022002:Hemidesmosomes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D015603:Keratinocytes / Q000378:metabolism / Q000648:ultrastructure; D051379:Mice; D032342:Muscle Cells / Q000166:cytology / Q000378:metabolism; D020125:Mutation, Missense / Q000235:genetics; D051190:Plectin / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D059748:Proteolysis; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D004151:Dipeptides; C495333:Plec protein, mouse; D051190:Plectin; D020033:Protein Isoforms; D011994:Recombinant Proteins; D002154:Calpain; C058076:calpain inhibitor III