RESUMO
Human endothelial cells (EC) are typically resistant to the apoptotic effects of stimuli associated with lung disease. The determinants of this resistance remain incompletely understood. Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine produced by human pulmonary artery EC (HPAEC). Its expression increases in response to various death-inducing stimuli, including lipopolysaccharide (LPS). We show here that silencing MIF expression by RNA interference (MIF siRNA) dramatically reduces MIF mRNA expression and the LPS-induced increase in MIF protein levels, thereby sensitizing HPAECs to LPS-induced cell death. Addition of recombinant human MIF (rhMIF) protein prevents the death-sensitizing effect of MIF siRNA. A common mediator of apoptosis resistance in ECs is the death effector domain (DED)-containing protein, FLIP (FLICE-like inhibitory protein). We show that LPS induces a transcription-independent increase in the short isoform of FLIP (FLIP(s)). This increase is blocked by MIF siRNA but restored with the addition of recombinant MIF protein (rHMIF). While FLIP(s) siRNA also sensitizes HPAECs to LPS-induced death, the addition of rhMIF does not affect this sensitization, placing MIF upstream of FLIP(s) in preventing HPAEC death. These studies demonstrate that MIF is an endogenous pro-survival factor in HPAECs and identify a novel mechanism for its role in apoptosis resistance through the regulation of FLIP(s). These results show that MIF can protect vascular endothelial cells from inflammation-associated cell damage.
Assuntos
Apoptose/efeitos dos fármacos , Endotélio Vascular/fisiologia , Lipopolissacarídeos/toxicidade , Fatores Inibidores da Migração de Macrófagos/genética , Artéria Pulmonar/fisiologia , Mucosa Respiratória/citologia , Mucosa Respiratória/fisiologia , Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD/genética , Proteína Reguladora de Apoptosis Semelhante a CASP8 e FADD/metabolismo , Morte Celular/efeitos dos fármacos , Primers do DNA , Endotélio Vascular/citologia , Endotélio Vascular/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Fatores Inibidores da Migração de Macrófagos/fisiologia , Artéria Pulmonar/citologia , Artéria Pulmonar/efeitos dos fármacos , Interferência de RNA , RNA Mensageiro/genética , RNA Interferente Pequeno/genética , Mucosa Respiratória/efeitos dos fármacos , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
As a model for Neuropsychiatric dysfunction in NeuroAIDS due to HIV-1 infection and drug abuse, we analyzed gene expression in human neurons treated with cocaine and HIV-1 proteins tat and envelope (env). One-way ANOVA showed statistically significant genes among the treatment groups (p < or = 0.0005). The identified genes were then subjected to a "stepwise" analysis using a repeated measures ANOVA to discover genes with parallel response group profiles across the treatment conditions. These groups were then analyzed using a repeated measures ANOVA to assess treatment main effects and gene-by-treatment interactions within groups. One-way ANOVA produced 35 genes that were significantly associated across all treatment conditions. Factorial analysis of each gene found statistically significant differences: 30--tat, 17--cocaine, 10--env, 6--tat/env, 6--coc/env, and 4--coc/tat. Analyses across genes found three sets of four genes, one set of three genes, and three sets of two genes with parallel profiles. Identified genes had functions included signaling, immune related, and transcription control. The genes were not stochastically arranged on the chromosomes, were in proximity to each other, and to other genes involved in neuropsychiatric diseases. We hypothesize that these genes fall in transcriptionally isolated groups and that abused drugs and HIV-1 proteins trigger transcription overload, coerced expression that may result in damage to the chromosome's control and organization of chromatin transcription machinery.