Regulation of inducible heparanase gene transcription in activated T cells by early growth response 1
Regulation of inducible heparanase gene transcription in activated T cells by early growth response 1
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DOI：
10.1074/jbc.m310154200
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发表时间：
2003-12-12
影响因子：
4.8
通讯作者：
Hulett, MD
中科院分区：
文献类型：
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作者：
de Mestre, AM;Khachigian, LM;Hulett, MD
在炎症、伤口愈合和血管生成等重要生理过程中，β-D-内切糖醛酸乙酰肝素酶(HPSE)对硫酸乙酰肝素的裂解是一个基本事件。HPSE活性也与肿瘤生长和转移以及自身免疫性疾病等病理条件直接相关。HPSE的表达和功能的严密调控对于确保其所参与的正常生理过程的动态平衡和防止向病理状态的失衡至关重要。对调节HPSE表达的转录机制知之甚少。在这项研究中，我们证明了人HPSE基因在Jurkat T细胞中的转录是在激活后被诱导的。对HPSE启动子的功能分析已经确定了一个280bp的高度诱导区域。突变研究和超移位实验已经确定了一个4个碱基的基序，它结合了转录因子早期生长反应-1(Egr1)，在调节可诱导的HPSE基因转录方面起着关键作用。此外，Egr1的过表达导致HPSE启动子的激活增强。通过使用MAPK途径抑制剂，我们还证明了HPSE mRNA的诱导表达和280个碱基的HPSE启动子元件的活性依赖于ERK1/2(MEK1/2)途径。这一途径对于诱导T细胞中Egr1在mRNA和蛋白水平上的表达是至关重要的，这进一步支持了Egr1作为HPSE表达的关键激活物发挥重要作用。此外，免疫组织化学显示，在主动诱导的实验性自身免疫性脑脊髓炎大鼠中，HPSE和Egr1共同定位于侵袭的单核白细胞。这些发现提供了对HPSE基因可诱导转录的控制机制的第一次洞察，并可能为理解HPSE在转移瘤细胞中的表达如何被解除调控提供了重要的线索。
Cleavage of heparan sulfate by the beta-D-endoglucuronidase heparanase (HPSE) is a fundamental event in a number of important physiological processes including inflammation, wound healing, and angiogenesis. HPSE activity has also been directly correlated with pathological conditions such as tumor growth and metastasis and autoimmune disease. The tight regulation of HPSE expression and function is critical to ensure homeostasis of the normal physiological processes to which it contributes and to prevent imbalance toward pathological situations. Little is known about the transcriptional mechanisms that regulate HPSE expression. In this study we have shown human HPSE gene transcription in Jurkat T cells is induced upon activation. Functional analysis of the HPSE promoter has identified a 280-bp region that is highly inducible. Mutation studies together with supershift experiments have identified a 4-bp motif that binds the transcription factor early growth response-1 (Egr1) and is critical in regulating inducible HPSE gene transcription. Furthermore, the overexpression of Egr1 resulted in the enhanced activation of the HPSE promoter. By using MAPK pathway inhibitors, we have also shown that inducible expression of HPSE mRNA and the activity of the 280-bp HPSE promoter element are dependent on the ERK1/2 (MEK1/2) pathway. This pathway is critical for induction of Egr1 expression at both the mRNA and protein level in T cells, an observation that provides further support to Egr1 playing an important role as a key activator of HPSE expression. In addition, HPSE and Egr1 were shown to co-localize by immunohistochemistry to invading mononuclear leukocytes in actively induced experimental autoimmune encephalomyelitis in rats. These findings provide the first insight into the mechanisms controlling inducible transcription of the HPSE gene, and could represent an important lead into understanding how HPSE expression is deregulated in metastatic tumor cells.