BACKGROUND: Epidermolytic hyperkeratosis (bullous congenital ichthyosiform erythroderma), characterized by ichthyotic, rippled hyperkeratosis, erythroderma and skin blistering, is a rare autosomal dominant disease caused by mutations in keratin 1 or keratin 10 (K10) genes. A severe phenotype is caused by a missense mutation in a highly conserved arginine residue at position 156 (R156) in K10. OBJECTIVES: To analyse molecular pathomechanisms of hyperproliferation and hyperkeratosis, we investigated the defects in mechanosensation and mechanotransduction in keratinocytes carrying the K10(R156H) mutation. METHODS: Differentiated primary human keratinocytes infected with lentiviral vectors carrying wild-type K10 (K10(wt)) or mutated K10(R156H) were subjected to 20% isoaxial stretch. Cellular fragility and mechanosensation were studied by analysis of mitogen-activated protein kinase activation and cytokine release. RESULTS: Cultured keratinocytes expressing K10(R156H) showed keratin aggregate formation at the cell periphery, whereas the filament network in K10(wt) cells was normal. Under stretching conditions K10(R156H) keratinocytes exhibited about a twofold higher level of filament collapse compared with steady state. In stretched K10(R156H) cells, higher p38 activation, higher release of tumour necrosis factor-α and RANTES but reduced interleukin-1β secretion compared with K10(wt) cells was observed. CONCLUSIONS: These results demonstrate that the R156H mutation in K10 destabilizes the keratin intermediate filament network and affects stress signalling and inflammatory responses to mechanical stretch in differentiated cultured keratinocytes.
BACKGROUND: Epidermolytic hyperkeratosis (bullous congenital ichthyosiform erythroderma), characterized by ichthyotic, rippled hyperkeratosis, erythroderma and skin blistering, is a rare autosomal dominant disease caused by mutations in keratin 1 or keratin 10 (K10) genes. A severe phenotype is caused by a missense mutation in a highly conserved arginine residue at position 156 (R156) in K10. OBJECTIVES: To analyse molecular pathomechanisms of hyperproliferation and hyperkeratosis, we investigated the defects in mechanosensation and mechanotransduction in keratinocytes carrying the K10(R156H) mutation. METHODS: Differentiated primary human keratinocytes infected with lentiviral vectors carrying wild-type K10 (K10(wt)) or mutated K10(R156H) were subjected to 20% isoaxial stretch. Cellular fragility and mechanosensation were studied by analysis of mitogen-activated protein kinase activation and cytokine release. RESULTS: Cultured keratinocytes expressing K10(R156H) showed keratin aggregate formation at the cell periphery, whereas the filament network in K10(wt) cells was normal. Under stretching conditions K10(R156H) keratinocytes exhibited about a twofold higher level of filament collapse compared with steady state. In stretched K10(R156H) cells, higher p38 activation, higher release of tumour necrosis factor-α and RANTES but reduced interleukin-1β secretion compared with K10(wt) cells was observed. CONCLUSIONS: These results demonstrate that the R156H mutation in K10 destabilizes the keratin intermediate filament network and affects stress signalling and inflammatory responses to mechanical stretch in differentiated cultured keratinocytes.