Serum DNase I activity can be used as a sensitive marker for detection of acute myocardial infarction

我们证明，血清DNase I活性可作为早期发现急性心肌梗死(AMI)的新的诊断指标，急性心肌梗死患者在出现症状后3h内，血清DNase I活性水平突然升高，从而在获得准确的CK-MB和c-TnT结果之前即可诊断急性心肌梗死。此外，我们还研究了在经皮冠状动脉介入治疗(PCI)中诱导的短暂缺血后血清DNase I水平的变化。介入治疗完成后3h，血清DNase I活性较术前显著升高。然而，急性心肌梗死或经皮冠状动脉介入治疗期间缺血引起血清DNase I活性升高的机制尚不清楚。为了阐明这一现象的分子基础，了解人类DNase I基因(DNase1)表达的调控机制是重要的。我们首先在人类胰腺和产生人pancr…的DNaseI中定位了DNase1的转录起始点并在外显子1的上游发现了一个新的12kb的位置，以前认为它是单一的转录起始外显子。这个起始点标记了另一个起始外显子，命名为1a。在胰腺和QGP-1细胞中同时使用外显子1和1a作为转录起始外显子。启动子分析、EMSA和染色质免疫沉淀分析表明，启动子1a外显子1a的启动子区域，其中Sp1转录因子是特异参与启动子活性的。这是第一个被鉴定为负责脊椎动物DNase I基因表达的转录因子。此外，RT-PCR分析表明，人DNase1前mRNA在胰腺和QGP-1细胞中存在选择性剪接。在已确定的八种选择性剪接产物中，只有两种转录本可以被翻译成完整的DNaseI蛋白。这些结果表明，人类DNase1的表达是通过使用选择性启动子和选择性剪接来调节的。较少

We demonstrated that serum DNase I activity could be used as novel diagnostic marker for the early detection of acute myocardial infarction (AMI) ; abrupt elevation of serum DNase I activity levels occurs within 3h of the onset of symptoms in patients with AMI, permitting the diagnosis of AMI before accurate CK-MB and c-TnT results become available. Moreover, we investigated alterations in serum DNase I levels after transient ischemia induced during percutaneous coronary intervention(PCI). Serum DNase I activity had risen significantly from base line by 3h after completion of the PCI procedure. However, the mechanism for the elevation of serum DNase I activity induced by ischemia during AMI or PCI remain to be elucidated. To elucidate the molecular basis of this phenomenon, it is important to understand the regulatory mechanism of the human DNase I gene(DNASE1) expression. We first mapped the transcription start sites of DNASE1 in human pancreas and in the DNase I producing human pancr … More eatic cancer cell line QGP-1, and revealed a novel site 12kb upstream of exon 1, which was previously believed to be the single transcription starting exon. This initiation site markes an alternative starting exon, designated 1a. Exon 1 and 1a were used simultaneously as transcription starting exon in pancreas and QGP-1 cells. Promoter assay EMSA and chromatin immunoprecipitation analysis with QGP-1 cell lines showed that the promoter region of exon 1a in which the Sp1 transcription factor is specifically involved in promoter activity. This is the first to be identified as a transcription factor responsible for gene expression of vertebrate DNase I gene. Furthermore, RT-PCR analysis indicated alternative splicing of human DNase 1 pre-mRNA in pancreas and QGP-1 cells. Only two transcripts among eight alternative splicing products identified can be translated to produce intact DNase I protein. These results suggested that human DNase 1 expression is regulated through the use of alternative promoter and alternative splicing. Less