Institute of Neuroscience and Physiology, Department of Clinical Neuroscience and Rehabilitation, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
J Neurosci Res. 2010 Aug 15;88(11):2441-9. doi: 10.1002/jnr.22412.
Astrocytes play a diverse role in central nervous system (CNS) injury. Production of the serine protease inhibitors (serpins) plasminogen activator inhibitor-1 (PAI-1) and protease nexin-1 (PN-1) by astrocytes may counterbalance excessive serine protease activity associated with CNS pathologies such as ischemic stroke. Knowledge regarding the regulation of these genes in the brain is limited, so the objective of the present study was to characterize the effects of injury-related factors on serpin expression in human astrocytes. Native human astrocytes were exposed to hypoxia or cytokines, including interleukin-6 (IL-6), IL-1beta, tumor necrosis factor-alpha (TNF-alpha), IL-10, transforming growth factor-alpha (TGF-alpha), and TGF-beta for 0-20 hr. Serpin mRNA expression and protein secretion were determined by real-time RT-PCR and ELISA, respectively. Localization of PAI-1 and PN-1 in human brain tissue was examined by immunohistochemistry. Hypoxia and all assayed cytokines induced a significant increase in PAI-1 expression, whereas prolonged treatment with IL-1beta or TNF-alpha resulted in a significant down-regulation. The most pronounced induction of both PAI-1 and PN-1 was observed following early treatment with TGF-alpha. In contrast to PAI-1, the PN-1 gene did not respond to hypoxia. Positive immunoreactivity for PAI-1 in human brain tissue was demonstrated in reactive astrocytes within gliotic areas of temporal cortex. We show here that human astrocytes express PAI-1 and PN-1 and demonstrate that this astrocytic expression is regulated in a dynamic manner by injury-related factors.
星形胶质细胞在中枢神经系统 (CNS) 损伤中发挥着多样化的作用。星形胶质细胞产生的丝氨酸蛋白酶抑制剂 (serpins) 纤溶酶原激活物抑制剂-1 (PAI-1) 和蛋白酶神经素-1 (PN-1) 可能会抵消与缺血性中风等 CNS 病理相关的过度丝氨酸蛋白酶活性。关于这些基因在大脑中的调控知识有限，因此本研究的目的是描述与损伤相关的因素对人星形胶质细胞中丝氨酸蛋白酶抑制剂表达的影响。将原代人星形胶质细胞暴露于缺氧或细胞因子，包括白细胞介素-6 (IL-6)、白细胞介素-1β (IL-1β)、肿瘤坏死因子-α (TNF-α)、白细胞介素-10 (IL-10)、转化生长因子-α (TGF-α) 和转化生长因子-β (TGF-β) 0-20 小时。通过实时 RT-PCR 和 ELISA 分别测定丝氨酸蛋白酶抑制剂 mRNA 表达和蛋白分泌。通过免疫组织化学检查人脑组织中 PAI-1 和 PN-1 的定位。缺氧和所有检测到的细胞因子均诱导 PAI-1 表达显著增加，而长时间用 IL-1β 或 TNF-α 处理则导致显著下调。在早期用 TGF-α 处理后，观察到 PAI-1 和 PN-1 的表达均最明显诱导。与 PAI-1 不同，PN-1 基因对缺氧没有反应。在颞叶皮质胶质增生区的反应性星形胶质细胞中证实了人脑组织中 PAI-1 的阳性免疫反应性。我们在此表明，人星形胶质细胞表达 PAI-1 和 PN-1，并证明这种星形胶质细胞表达受损伤相关因素的动态调控。
