RESUMO
BACKGROUND: Prior experimentation has shown that loss of the tyrosine kinase (TK) signaling domain of the Ron receptor leads to marked hepatocyte protection in a model of lipopolysaccharide-induced acute liver failure (ALF) in D-galactosamine (GalN)-sensitized mice. The aim of this study was to identify the role of Ron in the regulation of hepatic gene expression. METHODS: Microarray analyses were performed on liver RNA isolated sequentially from wild-type (WT) and TK-/- mice during the progression of ALF. Gene array data were validated using Western and immunohistochemistry analyses as well as with ex vivo culture systems. RESULTS: At baseline, 101 genes were differentially expressed between WT and TK-/- livers, which regulate processes involved in hypoxia, proliferation, apoptosis and metabolism. One hour after ALF induction, WT livers exhibited increased cytokine expression compared to TK-/- livers, and after 4 hours, an induction of suppressor of cytokine signaling (SOCS) genes as well as JAK-STAT pathway activation were prominent in TK-/- livers compared to controls. CONCLUSION: Our studies suggest a novel hepato-protective mechanism in Ron TK-/- mice wherein increased and sustained SOCS production and JAK-STAT activation in the hepatocyte may inhibit the destructive proinflammatory milieu and promote survival factors which blunt hepatic death and the ensuing development of ALF.
Assuntos
Lipopolissacarídeos , Falência Hepática Aguda/enzimologia , Fígado/enzimologia , Receptores Proteína Tirosina Quinases/metabolismo , Animais , Apoptose , Western Blotting , Células Cultivadas , Citocinas/genética , Citocinas/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Galactosamina , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica , Imuno-Histoquímica , Mediadores da Inflamação/metabolismo , Janus Quinases/genética , Janus Quinases/metabolismo , Fígado/patologia , Falência Hepática Aguda/induzido quimicamente , Falência Hepática Aguda/genética , Falência Hepática Aguda/patologia , Falência Hepática Aguda/prevenção & controle , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Análise de Sequência com Séries de Oligonucleotídeos , Receptores Proteína Tirosina Quinases/deficiência , Receptores Proteína Tirosina Quinases/genética , Fatores de Transcrição STAT/genética , Fatores de Transcrição STAT/metabolismo , Transdução de Sinais , Proteínas Supressoras da Sinalização de Citocina/genética , Proteínas Supressoras da Sinalização de Citocina/metabolismo , Fatores de TempoRESUMO
Previous studies have shown that mice deficient in the tyrosine kinase domain (TK-/-) of the receptor Mst1r have an increased susceptibility to nickel (Ni)-induced acute lung injury (ALI). Mst1r TK-/- mice have decreased survival times, alterations in cytokine and nitric oxide regulation, and an earlier onset of pulmonary pathology compared with control mice, suggesting that Mst1r signaling, in part, may regulate the response to ALI. To examine the role of Mst1r in ALI in more detail, we compared the gene expression profiles of murine lung mRNA from control and Mst1r TK-/- mice at baseline and after 24 h of particulate Ni sulfate exposure. Microarray analyses showed a total of 343 transcripts that were significantly changed, either by Ni treatment, or between genotypes. Genes responsible for inflammation, edema, and lymphocyte function were altered in the Mst1r TK-/- mice. Interestingly, the genes for several granzymes were increased in Mst1r TK-/- mice before Ni exposure, compared with controls. In addition, the Mst1r TK-/- lungs showed clusters of cells near the vascular endothelium and airways. Immunohistochemistry indicates these clusters are composed of macrophages, T cells, and neutrophils, and that the clusters display granzyme protein production. These results suggest that Mst1r signaling may be involved in the regulation of macrophage and T-lymphocyte activation in vivo during injury. This assessment of gene expression indicates the importance of genetic factors in contributing to lung injury, and points to strategies for intervention in the progression of inflammatory diseases.
Assuntos
Perfilação da Expressão Gênica , Irritantes/toxicidade , Níquel/toxicidade , Receptores Proteína Tirosina Quinases/fisiologia , Síndrome do Desconforto Respiratório , Animais , Análise por Conglomerados , Pulmão/citologia , Pulmão/patologia , Pulmão/fisiologia , Macrófagos/metabolismo , Camundongos , Camundongos Knockout , Dados de Sequência Molecular , Análise de Sequência com Séries de Oligonucleotídeos , RNA Mensageiro/metabolismo , Receptores Proteína Tirosina Quinases/genética , Síndrome do Desconforto Respiratório/induzido quimicamente , Síndrome do Desconforto Respiratório/imunologia , Síndrome do Desconforto Respiratório/fisiopatologia , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismo , Transdução de Sinais/fisiologia , Linfócitos T/metabolismoRESUMO
Ca(2+)/calmodulin-regulated protein kinase II (CaMKII) mediates many cellular events. The four CaMKII isoforms have numerous splice variants, three of which contain nuclear localization signals. Little is known about the role of nuclear localized CaMKII in neuronal development. To study this process, PC12 cells were transfected to produce CaMKII targeted to either the cytoplasm or the nucleus and then treated with nerve growth factor (NGF). NGF triggers a signaling cascade (MAPK) that results in the differentiation of PC12 cells into a neuronal phenotype, marked by neurite outgrowth. The present study found that cells expressing nuclear targeted CaMKII failed to grow neurites, whereas cells expressing cytoplasmic CaMKII readily produced neurites. Inhibition of neuronal differentiation by nuclear CaMKII was independent of MAPK signaling, as sustained Erk phosphorylation was not affected. Phosphorylation of CREB was also unaffected. Thus nuclear CaMKII modifies neuronal differentiation by a mechanism independent of MAPK and CREB activation.
