RESUMEN
Mitochondrial dysfunction activates the mitochondrial retrograde signaling pathway, resulting in large scale changes in gene expression. Mitochondrial retrograde signaling in neurons is poorly understood and whether retrograde signaling contributes to cellular dysfunction or is protective is unknown. We show that inhibition of Ras-ERK-ETS signaling partially reverses the retrograde transcriptional response to alleviate neuronal mitochondrial dysfunction. We have developed a novel genetic screen to identify genes that modify mitochondrial dysfunction in Drosophila. Knock-down of one of the genes identified in this screen, the Ras-ERK-ETS pathway transcription factor Aop, alleviates the damaging effects of mitochondrial dysfunction in the nervous system. Inhibition of Ras-ERK-ETS signaling also restores function in Drosophila models of human diseases associated with mitochondrial dysfunction. Importantly, Ras-ERK-ETS pathway inhibition partially reverses the mitochondrial retrograde transcriptional response. Therefore, mitochondrial retrograde signaling likely contributes to neuronal dysfunction through mis-regulation of gene expression.
Asunto(s)
Drosophila/fisiología , Regulación de la Expresión Génica/fisiología , Mitocondrias/metabolismo , Neuronas/metabolismo , Transducción de Señal/fisiología , Animales , Animales Modificados Genéticamente , Conducta Animal/fisiología , Modelos Animales de Enfermedad , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Proteínas del Ojo/genética , Proteínas del Ojo/metabolismo , Femenino , Perfilación de la Expresión Génica , Técnicas de Silenciamiento del Gen , Humanos , Enfermedad de Leigh/genética , Enfermedad de Leigh/patología , Masculino , Proteínas Mitocondriales/genética , Neuronas/citología , Trastornos Parkinsonianos/genética , Trastornos Parkinsonianos/patología , Proteínas Proto-Oncogénicas c-ets/metabolismo , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Ubiquitina-Proteína Ligasas/genética , Proteínas ras/metabolismoRESUMEN
Leishmania donovani is an obligatory intracellular pathogen that resides and multiplies in the phagolysosomes of macrophages. The outcome of this infection depends on the balance between the host ability to activate macrophage killing and the parasite ability to suppress or evade this host immune response. Lipophosphoglycan (LPG) glycoconjugate, the surface molecule of the protozoan parasite is a virulence determinant and a major parasite molecule involved in this process. In this study, we examined the ability of Leishmania and its surface molecule, lipophosphoglycan to activate activating protein 1 (AP-1) through the mitogen-activated protein kinase (MAPK) cascade. We report here that the Leishmania surface molecule, lipophosphoglycan stimulates the simultaneous activation of all three classes of MAP kinases, extracellular signal-related kinases (ERKs), the c-jun amino-terminal kinase (JNK) and the p38 MAP kinase with differential kinetics in J774A.1 macrophage cell line. Furthermore, both L. donovani and its surface molecule lipophosphoglycan resulted in a dose- and time-dependent induction of AP-1 DNA-binding activity. We have also shown a dose-dependent increase of AP-1 binding activity in both low and high virulent strains of parasite. The use of inhibitors selective for ERK (PD98059) and p38 (SB203580) pathway showed that pre-incubation of cells with either SB203580 or PD98059 affected the binding activity of AP-1 suggesting that both p38 and ERK MAP kinase activation appear to be necessary for AP-1 activation by LPG. Lipophosphoglycan induced IL-12 production and generation of nitric oxide in murine macrophages. These results demonstrate that L. donovani LPG activates pro-inflammatory, endotoxin-like response pathway in J774A.1 macrophages and the interaction may play a pivotal role in the elimination of the parasite.
