RESUMEN
Wnt5a is a ligand that activates the noncanonical Wnt signaling pathways (beta-catenin-independent pathways). Human neutrophils expressed several Wnt5a receptors, such as Frizzled 2, 5 and 8. Stimulation of human neutrophils with Wnt5a caused chemotactic migration and the production of two important chemokines, CXCL8 and CCL2. CCL2 production by Wnt5a was mediated by a pertussis toxin-sensitive G-protein-dependent pathway. Wnt5a also stimulated the phosphorylation of three mitogen-activated protein kinases (MAPKs: ERK, p38 MAPK and JNK) and Akt. Inhibition of ERK, p38 MAPK or JNK by specific inhibitors induced a dramatic reduction in Wnt5a-induced CCL2 production. Supernatant collected from lipopolysaccharide-stimulated macrophages induced neutrophil chemotaxis, which was significantly inhibited by anti-Wnt5a antibody. Our results suggested that Wnt5a may contribute to neutrophil recruitment, mediating the inflammation response.
Asunto(s)
Animales , Humanos , Ratones , Factor de Transcripción Activador 2/metabolismo , Separación Celular , Quimiocinas/biosíntesis , Quimiotaxis/efectos de los fármacos , Medios de Cultivo Condicionados/farmacología , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Proteínas de Unión al GTP/metabolismo , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Lipopolisacáridos/farmacología , Macrófagos/efectos de los fármacos , FN-kappa B/metabolismo , Neutrófilos/citología , Toxina del Pertussis/farmacología , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Receptores Wnt/metabolismo , Fosfolipasas de Tipo C/metabolismo , Proteínas Wnt/farmacología , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
PURPOSE: Lithium-pilocarpine induced status epilepticus (LPSE) causes selective and age-dependent neuronal death, although the mechanism of maturation-related injury has not yet been clarified. The activating transcription factor-2 (ATF-2) protein is essential for the normal development of mammalian brain and is activated by c-Jun N-terminal kinase (JNK). It induces the expression of the c-jun gene and modulates the function of the c-Jun protein, a mediator of neuronal death and survival. Therefore, we investigated the expression of c-Jun and ATF-2 protein in the immature and adult rat hippocampus to understand their roles in LPSE-induced neuronal death. MATERIALS AND METHODS: Lithium chloride was administrated to P10 and adult rats followed by pilocarpine. Neuronal injury was assessed by silver and cresyl violet staining, performed 72 hours after status epilepticus. For evaluation of the expression of ATF-2 and c-Jun by immunohistochemical method and Western blot, animals were sacrificed at 0, 4, 24, and 72 hours after the initiation of seizure. RESULTS: Neuronal injury and expression of c-Jun were maturation-dependently increased by LPSE, whereas ATF-2 immunoreactivity decreased in the mature brain. Since both c-Jun and ATF-2 are activated by JNK, and targets and competitors in the same signal transduction cascade, we could speculate that ATF-2 may compete with c-Jun for JNK phosphorylation. CONCLUSION: The results suggested a neuroprotective role of ATF-2 in this maturation-related evolution of neuronal cell death from status epilepticus.