The ESAT6 protein of Mycobacterium tuberculosis induces apoptosis of macrophages by activating caspase expression
The ESAT6 protein of Mycobacterium tuberculosis induces apoptosis of macrophages by activating caspase expression
复制标题
DOI：
10.1111/j.1462-5822.2007.00892.x
复制
发表时间：
2007-06-01
影响因子：
3.4
通讯作者：
Morris, Sheldon L.
中科院分区：
文献类型：
--
作者：
Derrick, Steven C.;Morris, Sheldon L.
结核分枝杆菌分泌蛋白 ESAT6 已在致病性和疫苗实验中得到广泛研究。尽管有这些研究，但人们对这种蛋白质的功能知之甚少。在本报告中，我们使用异硫氰酸荧光素-Annexin V 和细胞内 caspase 染色证明 ESAT6 诱导 THP-1 人巨噬细胞凋亡。我们表明，ESAT6 诱导细胞凋亡取决于蛋白质的剂量和 caspase 基因的表达。使用实时 RT-PCR，我们发现相对于未处理的细胞，用 ESAT6 处理的细胞中 caspase-1、-3、-5、-7 和 -8 基因的表达上调。此外，我们发现，虽然用野生型结核分枝杆菌菌株 H37Rv 感染 THP-1 细胞会在感染后 48 小时导致显着的细胞凋亡，但不表达 ESAT6 的缺失突变体未能诱导显着的细胞凋亡。最后，使用细胞不可渗透荧光染色剂的实验结果表明，膜孔的形成可能是 ESAT6 引发细胞凋亡反应的主要机制。
The secreted Mycobacterium tuberculosis protein, ESAT6, has been studied extensively in pathogenicity and vaccine experiments. Despite these studies little is known about the function of this protein. In this report, we demonstrate that ESAT6 induces apoptosis in THP-1 human macrophages using fluorescein isothiocyanate-Annexin V and intracellular caspase staining. We show that the induction of apoptosis by ESAT6 is dependent on the dose of the protein and the expression of caspase genes. Using real-time RT-PCR, we found that expression of caspase-1, -3, -5, -7 and -8 genes was upregulated in cells treated with ESAT6 relative to untreated cells. Furthermore, we show that while infection of THP-1 cells with wild-type M. tuberculosis strain H37Rv resulted in significant apoptosis 48 h post infection, a deletion mutant that does not express ESAT6 failed to induce significant apoptosis. Finally, experimental results using a cell impermeable fluorescent stain suggests that the formation of membrane pores may be a primary mechanism by which ESAT6 evokes an apoptotic response.