Asunto(s)
Proteínas de Unión al ADN/metabolismo , Endotelio Vascular/inmunología , Proteínas de Homeodominio , FN-kappa B/genética , Proteínas Nucleares , Proteínas/fisiología , Proteínas Proto-Oncogénicas/fisiología , Proteínas Represoras , Proteínas de Saccharomyces cerevisiae , Factores de Transcripción/metabolismo , Animales , Bovinos , Proteínas de Unión al ADN/efectos de los fármacos , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/fisiología , Endotelio Vascular/citología , Regulación de la Expresión Génica , Luciferasas/genética , Luciferasas/metabolismo , Antígenos de Histocompatibilidad Menor , FN-kappa B/efectos de los fármacos , Factores de Transcripción NFATC , Proteínas/genética , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-bcl-2/fisiología , Proteína de Replicación C , Factores de Transcripción/efectos de los fármacos , Factores de Transcripción/genética , Transfección , Proteína bcl-XRESUMEN
A1 is an anti-apoptotic bcl gene that is expressed in endothelial cells (EC) in response to pro-inflammatory stimuli. We show that in addition to protecting EC from apoptosis, A1 inhibits EC activation and its associated expression of pro-inflammatory proteins by inhibiting the transcription factor nuclear factor (NF)-kappaB. This new anti-inflammatory function gives a broader dimension to the protective role of A1 in EC. We also show that activation of NF-kappaB is essential for the expression of A1. Taken together, our data suggest that A1 downregulates not only the pro-apoptotic and pro-inflammatory response, but also its own expression, thus restoring a quiescent phenotype to EC.
Asunto(s)
Proteínas de Unión al ADN/genética , Endotelio Vascular/fisiología , Regulación de la Expresión Génica , Proteínas de Homeodominio , FN-kappa B/genética , Proteínas Proto-Oncogénicas c-bcl-2 , Proteínas Represoras , Proteínas de Saccharomyces cerevisiae , Apoptosis/fisiología , Células Cultivadas , Humanos , Inflamación , Antígenos de Histocompatibilidad Menor , Proteína de Replicación CAsunto(s)
Proteínas I-kappa B , Músculo Liso Vascular/fisiología , Proteínas/fisiología , Animales , Aorta , Células Cultivadas , Cricetinae , Citocinas/farmacología , Proteínas de Unión al ADN/fisiología , Trasplante de Corazón/inmunología , Trasplante de Corazón/fisiología , Humanos , Péptidos y Proteínas de Señalización Intracelular , Músculo Liso Vascular/citología , Inhibidor NF-kappaB alfa , FN-kappa B/antagonistas & inhibidores , Proteínas Nucleares , Proteínas/genética , Ratas , Proteínas Recombinantes/biosíntesis , Transfección , Trasplante Heterólogo/inmunología , Trasplante Heterólogo/fisiología , Proteína 3 Inducida por el Factor de Necrosis Tumoral alfa , Factor de Necrosis Tumoral alfa/farmacologíaRESUMEN
To maintain the integrity of the vascular barrier, endothelial cells (EC) are resistant to cell death. The molecular basis of this resistance may be explained by the function of antiapoptotic genes such as bcl family members. Overexpression of Bcl-2 or Bcl-XL protects EC from tumor necrosis factor (TNF)-mediated apoptosis. In addition, Bcl-2 or Bcl-XL inhibits activation of NF-kappaB and thus upregulation of proinflammatory genes. Bcl-2-mediated inhibition of NF-kappaB in EC occurs upstream of IkappaBalpha degradation without affecting p65-mediated transactivation. Overexpression of bcl genes in EC does not affect other transcription factors. Using deletion mutants of Bcl-2, the NF-kappaB inhibitory function of Bcl-2 was mapped to bcl homology domains BH2 and BH4, whereas all BH domains were required for the antiapoptotic function. These data suggest that Bcl-2 and Bcl-XL belong to a cytoprotective response that counteracts proapoptotic and proinflammatory insults and restores the physiological anti-inflammatory phenotype to the EC. By inhibiting NF-kappaB without sensitizing the cells (as with IkappaBalpha) to TNF-mediated apoptosis, Bcl-2 and Bcl-XL are prime candidates for genetic engineering of EC in pathological conditions where EC loss and unfettered activation are undesirable.
Asunto(s)
Apoptosis , Proteínas I-kappa B , FN-kappa B/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/biosíntesis , Animales , Línea Celular Transformada , Células Cultivadas , Cicloheximida/farmacología , Proteínas de Unión al ADN/metabolismo , Endotelio Vascular/citología , Humanos , Ratones , Inhibidor NF-kappaB alfa , Proteínas Proto-Oncogénicas c-bcl-2/genética , Factor de Transcripción Sp1/metabolismo , Factor de Transcripción ReIA , Activación Transcripcional , Factor de Necrosis Tumoral alfa/farmacología , Proteína bcl-XRESUMEN
Expression of the NF-kappaB-dependent gene A20 in endothelial cells (EC) inhibits tumor necrosis factor (TNF)-mediated apoptosis in the presence of cycloheximide and acts upstream of IkappaBalpha degradation to block activation of NF-kappaB. Although inhibition of NF-kappaB by IkappaBalpha renders cells susceptible to TNF-induced apoptosis, we show that when A20 and IkappaBalpha are coexpressed, the effect of A20 predominates in that EC are rescued from TNF-mediated apoptosis. These findings place A20 in the category of "protective" genes that are induced in response to inflammatory stimuli to protect EC from unfettered activation and from undergoing apoptosis even when NF-kappaB is blocked. From a therapeutic perspective, genetic engineering of EC to express an NF-kappaB inhibitor such as A20 offers the mean of achieving an anti-inflammatory effect without sensitizing the cells to TNF-mediated apoptosis.