RESUMO
Brain plasticity provides a mechanism to compensate for lesions produced as a result of stroke. The present study aims to identify new transcription factors (TFs) following focal cerebral ischaemia in rat as potential therapeutic targets. A transient focal cerebral ischaemia model was used for TF-binding activity and TF-TF interaction profile analysis. A permanent focal cerebral ischaemia model was used for the transcript gene analysis and for the protein study. The identification of TF variants, mRNA analysis, and protein study was performed using conventional polymerase chain reaction (PCR), qPCR, and Western blot and immunofluorescence, respectively. Rat cortical neurons were transfected with small interfering RNA against the TF in order to study its role. The TF-binding analysis revealed a differential binding activity of the octamer family in ischaemic brain in comparison with the control brain samples both in acute and late phases. In this study, we focused on Oct-2 TF. Five of the six putative Oct-2 transcript variants are expressed in both control and ischaemic rat brain, showing a significant increase in the late phase of ischaemia. Oct-2 protein showed neuronal localisation both in control and ischaemic rat brain cortical slices. Functional studies revealed that Oct-2 interacts with TFs involved in important brain processes (neuronal and vascular development) and basic cellular functions and that Oct-2 knockdown promotes neuronal injury. The present study shows that Oct-2 expression and binding activity increase in the late phase of cerebral ischaemia and finds Oct-2 to be involved in reducing ischaemic-mediated neuronal injury.
Assuntos
Infarto da Artéria Cerebral Média/metabolismo , Proteínas do Tecido Nervoso/fisiologia , Fator 2 de Transcrição de Octâmero/fisiologia , Animais , Dano Encefálico Crônico/etiologia , Dano Encefálico Crônico/genética , Dano Encefálico Crônico/patologia , Dano Encefálico Crônico/prevenção & controle , Córtex Cerebral/metabolismo , Córtex Cerebral/patologia , Infarto Cerebral/genética , Infarto Cerebral/metabolismo , Infarto Cerebral/patologia , Imunoprecipitação da Cromatina , Progressão da Doença , Perfilação da Expressão Gênica , Infarto da Artéria Cerebral Média/genética , Infarto da Artéria Cerebral Média/patologia , Ataque Isquêmico Transitório/genética , Ataque Isquêmico Transitório/metabolismo , Masculino , Modelos Animais , Proteínas do Tecido Nervoso/biossíntese , Proteínas do Tecido Nervoso/genética , Neurônios/metabolismo , Fator 2 de Transcrição de Octâmero/biossíntese , Fator 2 de Transcrição de Octâmero/genética , Ligação Proteica , Interferência de RNA , RNA Mensageiro/biossíntese , RNA Interferente Pequeno/farmacologia , Ratos , Ratos Endogâmicos F344 , Transcrição Gênica , Regulação para CimaRESUMO
OCT-2 and its co-activator, BOB.1, are B-cell associated transcription factors expressed in a subset of patients with acute myeloid leukemia (AML). We evaluated OCT-2 and BOB.1 expression by immunohistochemistry in patients with newly diagnosed AML. The median overall survival (OS) for patients with varying levels of OCT-2 expression was statistically different (p = 0.03) (OCT-2 <10%: 21.7 months; OCT-2 10-50%: 18.4 months; OCT-2 >50%: 11.6 months). On multivariate analysis, co-expression of OCT-2/BOB.1 remained predictive for achievement of complete remission (HR 0.44, p = 0.010) and increased risk of relapse (HR 2.30, p = 0.047). OCT-2 (per 10% increase) was associated with a decreased progression-free survival (HR 1.10, p = 0.036) and a trend toward a worse OS (HR 1.10, p = 0.063). OCT-2 may act as a cell survival factor in AML by mediating expression of downstream targets, such as BCL-2. These results will need to be validated prospectively.