RESUMO
Decreased mitochondrial oxidative metabolism is a hallmark bioenergetic characteristic of malignancy that may have an adaptive role in carcinogenesis. By stimulating proton leak, mitochondrial uncoupling proteins (UCP1-3) increase mitochondrial respiration and may thereby oppose cancer development. To test this idea, we generated a mouse model that expresses an epidermal-targeted keratin-5-UCP3 (K5-UCP3) transgene and exhibits significantly increased cutaneous mitochondrial respiration compared with wild type (FVB/N). Remarkably, we observed that mitochondrial uncoupling drove keratinocyte/epidermal differentiation both in vitro and in vivo. This increase in epidermal differentiation corresponded to the loss of markers of the quiescent bulge stem cell population, and an increase in epidermal turnover measured using a bromodeoxyuridine (BrdU)-based transit assay. Interestingly, these changes in K5-UCP3 skin were associated with a nearly complete resistance to chemically-mediated multistage skin carcinogenesis. These data suggest that targeting mitochondrial respiration is a promising novel avenue for cancer prevention and treatment.
Assuntos
Diferenciação Celular , Transformação Celular Neoplásica/metabolismo , Canais Iônicos/metabolismo , Queratinócitos/citologia , Queratinócitos/metabolismo , Mitocôndrias/metabolismo , Proteínas Mitocondriais/metabolismo , Animais , Transformação Celular Neoplásica/induzido quimicamente , Epiderme/metabolismo , Expressão Gênica , Canais Iônicos/genética , Camundongos , Proteínas Mitocondriais/genética , Consumo de Oxigênio/fisiologia , Fase de Repouso do Ciclo Celular/genética , Pele/metabolismo , Pele/patologia , Células-Tronco/citologia , Células-Tronco/metabolismo , Proteína Desacopladora 3RESUMO
To clarify actions of vitamin A on mucosal immunity associated with interleukin-5 (IL-5), we examined effects of vitamin A on mucosal IgA level in IL-5 receptor alpha-chain-knockout (IL-5Ralpha(-/-)) mice. Daily supplementation of retinyl acetate (1 mg/mouse) increased Th2 cytokine levels and a number of their positive cells in the small intestinal mucosa of IL-5Ralpha(-/-) mice, as observed in wild-type or IL-5Ralpha(+/-) mice. Wild-type and heterozygous mice increased the IgA level and a number of IgA-containing cells in the mucosa in response to the vitamin A treatment, but not in IL-5Ralpha(-/-) mice. Retinyl acetate increased anti-cholera toxin (CT) IgA level in the mucosa of wild-type mice, improving their survival rate after an exposure to 0.4 mg of CT. However, retinyl acetate failed to induce resistance to CT toxicity in IL-5Ralpha(-/-) mice. Our results suggest that IL-5 may play an important role in an action of vitamin A on mucosal IgA system.
