RESUMO
RATIONALE: Innate and adaptive immune responses alter numerous homeostatic processes that are controlled by nuclear hormone receptors. NR4A1 is a nuclear receptor that is induced in vascular pathologies, where it mediates protection. OBJECTIVE: The underlying mechanisms that regulate the activity of NR4A1 during vascular injury are not clear. We therefore searched for modulators of NR4A1 function that are present during vascular inflammation. METHODS AND RESULTS: We report that the protein encoded by interferon stimulated gene 12 (ISG12), is a novel interaction partner of NR4A1 that inhibits the transcriptional activities of NR4A1 by mediating its Crm1-dependent nuclear export. Using 2 models of vascular injury, we show that ISG12-deficient mice are protected from neointima formation. This effect is dependent on the presence of NR4A1, as mice deficient for both ISG12 and NR4A1 exhibit neointima formation similar to wild-type mice. CONCLUSIONS: These findings identify a previously unrecognized feedback loop activated by interferons that inhibits the vasculoprotective functions of NR4A nuclear receptors, providing a potential new therapeutic target for interferon-driven pathologies.
Assuntos
Lesões das Artérias Carótidas/prevenção & controle , Artéria Femoral/metabolismo , Inflamação/prevenção & controle , Proteínas de Membrana/metabolismo , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/metabolismo , Proteínas/metabolismo , Lesões do Sistema Vascular/prevenção & controle , Transporte Ativo do Núcleo Celular , Animais , Lesões das Artérias Carótidas/genética , Lesões das Artérias Carótidas/imunologia , Lesões das Artérias Carótidas/metabolismo , Lesões das Artérias Carótidas/patologia , Células Cultivadas , Modelos Animais de Doenças , Células Endoteliais/metabolismo , Células Endoteliais/patologia , Retroalimentação Fisiológica , Artéria Femoral/lesões , Artéria Femoral/patologia , Regulação da Expressão Gênica , Inflamação/genética , Inflamação/imunologia , Inflamação/metabolismo , Inflamação/patologia , Interferons/metabolismo , Carioferinas/metabolismo , Proteínas de Membrana/genética , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Músculo Liso Vascular/lesões , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/patologia , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/patologia , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/genética , Domínios e Motivos de Interação entre Proteínas , Proteínas/genética , Interferência de RNA , Receptores Citoplasmáticos e Nucleares/metabolismo , Fatores de Tempo , Transcrição Gênica , Transfecção , Lesões do Sistema Vascular/genética , Lesões do Sistema Vascular/imunologia , Lesões do Sistema Vascular/metabolismo , Lesões do Sistema Vascular/patologia , Proteína Exportina 1RESUMO
The kinases of the Raf family have been intensively studied as activators of the mitogen-activated protein kinase kinase/extra-cellular signal-regulated kinase (ERK) module in regulated and deregulated proliferation. Genetic evidence that Raf is required for ERK activation in vivo has been obtained in lower organisms, which express only one Raf kinase, but was hitherto lacking in mammals, which express more than one Raf kinase. Ablation of the two best studied Raf kinases, B-Raf and Raf-1, is lethal at midgestation in mice, hampering the detailed study of the essential functions of these proteins. Here, we have combined conventional and conditional gene ablation to show that B-Raf is essential for ERK activation and for vascular development in the placenta. B-Raf-deficient placentae show complete absence of phosphorylated ERK and strongly reduced HIF-1alpha and VEGF levels, whereas all these parameters are normal in Raf-1-deficient placentae. In addition, neither ERK phosphorylation nor development are affected in B-raf-deficient embryos that are born alive obtained by epiblast-restricted gene inactivation. The data demonstrate that B-Raf plays a nonredundant role in ERK activation during extraembyronic mammalian development in vivo.