RESUMO
Although ultraviolet (UV) rays cause premature aging of human skin, which is called photoaging, its detailed mechanisms are not known. Stratifin (SFN), a member of the 14-3-3 protein family, is secreted by keratinocytes on human skin, and has an effect on gene expression in other cells. In this study, the association of SFN with the mechanism of photoaging was investigated. The effect of UVB irradiation on SFN expression in epidermal keratinocytes was examined by in vitro and in vivo studies. In addition, the effects of SFN on epidermal keratinocytes and dermal fibroblasts were examined. SFN mRNA expression and protein levels increased significantly in UVB-irradiated keratinocytes. SFN significantly decreased filaggrin and serine palmitoyltransferase mRNA expression in epidermal keratinocytes and hyaluronan synthase 2 mRNA expression in dermal fibroblasts. In addition, it was reconfirmed that SFN induces the downregulation of collagen content through changes of COL-1, MMP-1 and MMP-2 mRNA expressions. Furthermore, the expression level of SFN mRNA was significantly higher in sun-exposed compared with that in sun-shielded skin. These results suggest that SFN affects the water-holding capacity, barrier function and dermal matrix components in photoaging skin. An increase of SFN triggered by UVB irradiation may be one of the causes of alterations observed in photoaging skin.
Assuntos
Proteínas 14-3-3/metabolismo , Proteínas 14-3-3/efeitos da radiação , Biomarcadores Tumorais/metabolismo , Biomarcadores Tumorais/efeitos da radiação , Exorribonucleases/metabolismo , Exorribonucleases/efeitos da radiação , Envelhecimento da Pele/efeitos da radiação , Raios Ultravioleta/efeitos adversos , Proteínas 14-3-3/genética , Biomarcadores Tumorais/genética , Linhagem Celular , Colágeno Tipo I/genética , Epiderme/metabolismo , Epiderme/efeitos da radiação , Exorribonucleases/genética , Fibroblastos/metabolismo , Fibroblastos/efeitos da radiação , Proteínas Filagrinas , Expressão Gênica/efeitos da radiação , Glucuronosiltransferase/genética , Humanos , Hialuronan Sintases , Técnicas In Vitro , Queratinócitos/metabolismo , Queratinócitos/efeitos da radiação , Metaloproteinase 1 da Matriz/genética , Metaloproteinase 2 da Matriz/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Envelhecimento da Pele/fisiologiaRESUMO
PURPOSE: We describe variations of three radiation-induced endpoints on the basis of cell genotype: Clonogenic survival, expression of apoptosis and cell-cycle redistribution. METHODS: Clonogenic survival, apoptosis and cell-cycle redistribution are measured in multiple cell lines after exposure to radiation between 2 and 16 Gy. Cell lines varied in clonogenic radiosensitivity and expression of specific genes. RESULTS: Clonal radiosensitivity is genotype-dependent, associating with four specific genes: A mutated form of Ataxia telangiectasia mutated (mutATM); with two forms of TP53, the gene that is template for tumor protein p53, wildtype TP53 (wtTP53) and mutated TP53 (mutTP53); and an unidentified gene in radioresistant glioblastoma cells. Apoptosis is also genotype-dependent showing elevated levels in cells that express mutATM and abrogated 14-3-3sigma (an isoform of the 14-3-3 gene) but less variation for different forms of TP53. Cell-cycle redistribution varied in mutATM cells. Kinetics of apoptosis are biphasic for both time and dose; cell lines did not express apoptosis at doses below 5 Gy or times before 24 hours. Kinetics of cell-cycle redistribution changed dynamically in the first 24 hours but showed little change after that time. CONCLUSIONS: Clonogenic survival, radiation-induced apoptosis and radiation-induced redistribution in the cell-cycle vary with cell genotype, but not the same genotypes. There is temporal, not quantitative, correlation between apoptosis and clonal radiosensitivity with apoptosis suppressed by lower, less toxic doses of radiation (<5 Gy) but enabled after larger, more toxic doses. Kinetic patterns for apoptosis and redistribution show a common change at approximately 24 hours.
Assuntos
Apoptose/efeitos da radiação , Ciclo Celular/efeitos da radiação , Glioblastoma/radioterapia , Tolerância a Radiação/genética , Proteínas 14-3-3/genética , Proteínas 14-3-3/metabolismo , Proteínas 14-3-3/efeitos da radiação , Apoptose/genética , Apoptose/fisiologia , Proteínas Mutadas de Ataxia Telangiectasia , Ciclo Celular/genética , Ciclo Celular/fisiologia , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/efeitos da radiação , Sobrevivência Celular/genética , Sobrevivência Celular/fisiologia , Sobrevivência Celular/efeitos da radiação , Clonagem Molecular , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/efeitos da radiação , Relação Dose-Resposta à Radiação , Genes p53/genética , Genótipo , Glioblastoma/genética , Glioblastoma/patologia , Humanos , Cinética , Mutação , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Serina-Treonina Quinases/efeitos da radiação , Tolerância a Radiação/fisiologia , Células Tumorais Cultivadas , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Proteína Supressora de Tumor p53/efeitos da radiação , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismo , Proteínas Supressoras de Tumor/efeitos da radiaçãoRESUMO
14-3-3 proteins are relevant to cancer biology as they are key regulators of major cellular processes such as proliferation, differentiation, senescence and apoptosis. So far, the sigma isoform (14-3-3sigma) has most directly been implicated in carcinogenesis and was recognized as a tumour-suppressor gene. The other six members of the mammalian 14-3-3 gene family likely behave as oncogenes, although direct evidence supporting this view is largely circumstantial. In this report, we show that knockdown of 14-3-3zeta induces at least two isoform-specific phenotypes that are consistent with a potential oncogenic activity during tumorigenesis. Firstly, downregulation of 14-3-3zeta sensitized cells to stress-induced apoptosis and JNK/p38 signalling and secondly, it enforced cell-cell contacts and expression of adhesion proteins. Apparently, the zeta isoform restrains both cell adhesion and the cellular propensity for apoptosis, two activities that are also restrained during carcinogenesis. The assumption that 14-3-3zeta has oncogenic properties was substantiated with a web-based meta-analysis (Oncomine), revealing that 14-3-3zeta is overexpressed in various types of carcinomas. As the highly conserved human 14-3-3 gene family encodes proteins with either tumour-promoting or tumour-suppressing activities, we infer that the cellular balance between the various 14-3-3 isoforms is crucial for the proper functioning of cells.