RESUMO
The Nrf2 transcription factor is a key player in the cellular stress response through its regulation of cytoprotective genes. In this study we determined the role of Nrf2-mediated gene expression in keratinocytes for skin development, wound repair, and skin carcinogenesis. To overcome compensation by the related Nrf1 and Nrf3 proteins, we expressed a dominant-negative Nrf2 mutant (dnNrf2) in the epidermis of transgenic mice. The functionality of the transgene product was verified in vivo using mice doubly transgenic for dnNrf2 and an Nrf2-responsive reporter gene. Surprisingly, no abnormalities of the epidermis were observed in dnNrf2-transgenic mice, and even full-thickness skin wounds healed normally. However, the onset, incidence, and multiplicity of chemically induced skin papillomas were strikingly enhanced, whereas the progression to squamous cell carcinomas was unaltered. We provide evidence that the enhanced tumorigenesis results from reduced basal expression of cytoprotective Nrf target genes, leading to accumulation of oxidative damage and reduced carcinogen detoxification. Our results reveal a crucial role of Nrf-mediated gene expression in keratinocytes in the prevention of skin tumors and suggest that activation of Nrf2 in keratinocytes is a promising strategy to prevent carcinogenesis of this highly exposed organ.
Assuntos
Regulação Neoplásica da Expressão Gênica , Queratinócitos/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Neoplasias Cutâneas/prevenção & controle , Cicatrização , 9,10-Dimetil-1,2-benzantraceno/farmacologia , Fosfatase Alcalina/metabolismo , Animais , Western Blotting , Células COS , Testes de Carcinogenicidade , Carcinógenos/farmacologia , Técnicas de Cultura de Células , Células Cultivadas , Chlorocebus aethiops , Amarelo de Eosina-(YS)/metabolismo , Feminino , Imunofluorescência , Hematoxilina/metabolismo , Histocitoquímica , Hidroquinonas/farmacologia , Queratinócitos/citologia , Queratinócitos/efeitos dos fármacos , Queratinócitos/patologia , Camundongos , Camundongos Transgênicos , Microscopia de Fluorescência , Modelos Biológicos , Fator 2 Relacionado a NF-E2/genética , Neoplasias Cutâneas/induzido quimicamente , Acetato de Tetradecanoilforbol/farmacologiaRESUMO
Over the last decades numerous studies on the interfacial rheological response of protein adsorption layers have been published. The comparison of these studies and the retrieval of a common parameter to compare protein interfacial activity are hampered by the fact that different boundary conditions (e.g. physico-chemical, instrumental, interfacial) were used. In the present work we review previous studies and attempt a unifying approach for the comparison between bulk protein properties and their adsorption films. Among many common food grade proteins we chose bovine serum albumin, ß-lactoglobulin and lysozyme for their difference in thermodynamic stability and studied their adsorption at the air/water and limonene/water interface. In order to achieve this we have i) systematically analyzed protein adsorption kinetics in terms of surface pressure rise using a drop profile analysis tensiometer and ii) we addressed the interfacial layer properties under shear stress using an interfacial shear rheometer under the same experimental conditions. We could show that thermodynamically less stable proteins adsorb generally faster and yield films with higher shear rheological properties at air/water interface. The same proteins showed an analog behavior when adsorbing at the limonene/water interface but at slower rates.