A transgenic mouse model with an inducible skin blistering disease phenotype

Abstract

One of the current limitations of gene transfer protocols involving mammalian genomes is the lack of spatial and temporal control over the desired gene manipulation. Starting from a human keratin gene showing a complex regulation as a template, we identified regulatory sequences that confer inducible gene expression in a subpopulation of keratinocytes in stratified epithelia of adult transgenic mice. We used this cassette to produce transgenic mice with an inducible skin blistering phenotype mimicking a form of epidermolytic hyperkeratosis, a keratin gene disorder. Upon induction by topical application of a phorbol ester, the mutant keratin transgene product accumulates in the differentiating layers of epidermis, leading to keratinocyte lysis after application of mechanical trauma. This mouse model will allow for a better understanding of the complex relationship between keratin mutation, keratinocyte cytoarchitecture, and hypersensitivity to trauma. The development of an inducible expression vector showing an exquisite cellular specificity has important implications for manipulating genes in a spatially and temporally controlled fashion in transgenic mice, and for the design of gene therapy strategies using skin as a tissue source for the controlled delivery of foreign substances.

Delayed Wound Healing in Keratin 6a Knockout Mice

“…Elucidation of the significance of K6 expression in wound healing or its function in the epithelia with constitutive expression would not only further our understanding of K6 but also potentially provide insight into the biological necessity of having different sets of keratins for different cell types. We have shown that expression of dominant-negative mutants of K6 in the companion cell layer leads to the destruction of these cells (47), and Takahashi and colleagues reported on inducible skin blistering after induction of a dominant-negative K6 transgene in the epidermis (42). However, the functional significance of a protein is sometimes better evaluated by analyzing the consequences of its absence.…”

The Production and Applications of Genetically Modified Skin Cells

“…The skin blistering disease epidermolytic hyperkeratosis has been induced in a transgenic mouse model by expression of phorbol ester-inducible regulatory sequences in a subpopulation of keratinocytes. Application of a phorbol ester produces induction of a mutant keratin product and the onset of disease (Takahashi and Coulombe, 1996). The ability to induce model diseases at will in this way should allow a better understanding of their aetiology and conse~ quently their treatment with the gene modification techniques described in this review (see Figure 3).…”

Hsp40 regulates the amount of keratin proteins via ubiquitin-proteasome pathway in cultured human cells

“…One role that has been ascribed to various keratin filament networks of stratified squamous epithelia is to impart mechanical integrity to cells, without which the cells become fragile and prone to rupture (2). Disruption of the keratin IF network in epidermal keratinocytes via the targeted expression of dominant negative keratin mutants (3)(4)(5) or the introduction of null mutations (6) results in lysis of the targeted cell population whenever the skin of such mice is subjected to trivial mechanical trauma. Mutations in keratin genes, weakening the structural framework of cells, increase the risk of cell rupture and cause various human skin disorders (7,8).…”