Ejarque-Ortiz Aroa, Medina Manel G, Tusell Josep M, Pérez-González Anna P, Serratosa Joan, Saura Josep
Department of Pharmacology and Toxicology, IIBB-CSIC, IDIBAPS, E-08036 Barcelona, Spain.
Glia. 2007 Jan 15;55(2):178-88. doi: 10.1002/glia.20446.
The transcription factor CCAAT/enhancer binding protein beta (C/EBPbeta) regulates the expression of key genes in inflammation but little is known about the involvement of C/EBPbeta in glial activation. In this report, we have studied the patterns of astroglial and microglial C/EBPbeta expression in primary mouse cortical cultures. We show that both astrocytes and microglia express C/EBPbeta in untreated mixed glial cultures. C/EBPbeta is upregulated when glial activation is induced by lipopolysaccharide (LPS). The LPS-induced upregulation of glial C/EBPbeta is rapid (2 h at mRNA level, 4 h at protein level). It is elicited by low concentrations of LPS (almost maximal effect at 1 ng/mL) and it is reversed by the protein synthesis inhibitor cycloheximide. C/EBPbeta nuclear levels increase both in astrocytes and microglia after LPS treatment, and the response is more marked in microglia. The LPS-induced increase in microglial C/EBPbeta is prevented by coadministration of the MAP kinase inhibitors SB203580 (p38 inhibitor) + SP600125 (JNK inhibitor) or SB203580 + U0126 (ERK inhibitor). Systemic injection of LPS also increases brain nuclear levels of C/EBPbeta as shown by Western blot, and this increase is localized in microglial cells as shown by double immunofluorescence, in the first report to our knowledge of C/EBPbeta expression in activated glial cells in vivo. These findings support a role for C/EBPbeta in the activation of astrocytes and, particularly, microglia. Given the nature of the C/EBPbeta-regulated genes, we hypothesize that this factor participates in neurotoxic effects associated with glial activation. (c) 2006 Wiley-Liss, Inc.
转录因子CCAAT/增强子结合蛋白β（C/EBPβ）调节炎症相关关键基因的表达，但关于C/EBPβ在神经胶质细胞激活中的作用知之甚少。在本报告中，我们研究了原代小鼠皮质培养物中星形胶质细胞和小胶质细胞C/EBPβ的表达模式。我们发现，在未经处理的混合胶质细胞培养物中，星形胶质细胞和小胶质细胞均表达C/EBPβ。当脂多糖（LPS）诱导神经胶质细胞激活时，C/EBPβ表达上调。LPS诱导的神经胶质细胞C/EBPβ上调迅速（mRNA水平为2小时，蛋白质水平为4小时）。低浓度的LPS即可引发这种上调（1 ng/mL时几乎达到最大效应），并且蛋白质合成抑制剂环己酰亚胺可使其逆转。LPS处理后，星形胶质细胞和小胶质细胞中的C/EBPβ核水平均升高，且小胶质细胞中的反应更为明显。联合给予MAP激酶抑制剂SB203580（p38抑制剂）+ SP600125（JNK抑制剂）或SB203580 + U0126（ERK抑制剂）可阻止LPS诱导的小胶质细胞C/EBPβ增加。蛋白质印迹法显示，全身注射LPS也会增加脑细胞核中C/EBPβ的水平，如双重免疫荧光所示，这种增加定位于小胶质细胞中，据我们所知，这是关于体内激活的神经胶质细胞中C/EBPβ表达的首次报道。这些发现支持C/EBPβ在星形胶质细胞尤其是小胶质细胞激活中发挥作用。鉴于C/EBPβ调节基因的性质，我们推测该因子参与了与神经胶质细胞激活相关的神经毒性作用。（c）2006威利 - 利斯公司。
