Yabaji Shivraj M, Mishra Alok K, Chatterjee Aditi, Dubey Rikesh K, Srivastava Kanchan, Srivastava Kishore K
Division of Microbiology, CSIR-Central Drug Research Institute, Lucknow 226031, India; Academy of Scientific and Innovative Research, New Delhi 110025, India.
Division of Microbiology, CSIR-Central Drug Research Institute, Lucknow 226031, India.
Biochem Biophys Res Commun. 2017 Dec 16;494(3-4):433-439. doi: 10.1016/j.bbrc.2017.10.055. Epub 2017 Oct 12.
Early secretory antigenic target protein (ESAT-6) is an important virulent factor which plays a crucial role in Mycobacterium tuberculosis (MTB) pathogenesis. Here, we demonstrate the role of ESAT-6 in phagocytosis and intracellular survival of mycobacteria through a mechanism mediated by regulation of a host protein; Peroxiredoxin-1 (Prdx-1). Prdx-1 is an anti-apoptotic and stress response protein which protects cells from damage by ROS and HO. The J774 A.1 cells infected with MTB or over-expressing ESAT-6 through eukaryotic promoter vector showed elevated expression of Prdx-1. Further investigation revealed that the up-regulation of Prdx-1 is mediated through the activation of one of the MAP kinases, p38. The NRF-2, a transcriptional activator of Prdx-1 is translocated to the nucleus upon phosphorylation by p38 and subsequently, regulates expression of Prdx-1. Inhibition of the p38 MAPK by a specific inhibitor, SB203580, abrogates the ESAT-6 mediated induction of Prdx-1 expression as well as the phosphorylation of NRF-2 in a time-dependent manner. The inhibition of Prdx-1 expression by specific siRNA in J774 A.1 cells resulted in the reduced bacterial uptake and intracellular survival of the mycobacteria. This is the first report proclaiming that the ESAT-6 regulates Prdx-1 which is involved in the increase of mycobacterial uptake and survival. The intermediate mechanisms involve the increased Prdx-1 production in macrophages through the activation of p38 and NRF-2 dependent signaling.
早期分泌性抗原靶蛋白（ESAT-6）是一种重要的毒力因子，在结核分枝杆菌（MTB）致病过程中起关键作用。在此，我们通过宿主蛋白过氧化物酶1（Prdx-1）调控介导的机制，证明了ESAT-6在分枝杆菌吞噬作用和细胞内存活中的作用。Prdx-1是一种抗凋亡和应激反应蛋白，可保护细胞免受活性氧（ROS）和羟基自由基（HO）的损伤。感染MTB或通过真核启动子载体过表达ESAT-6的J774 A.1细胞显示Prdx-1表达升高。进一步研究表明，Prdx-1的上调是通过丝裂原活化蛋白激酶（MAPK）之一p38的激活介导的。Prdx-1的转录激活因子NRF-2在被p38磷酸化后易位至细胞核，随后调节Prdx-1的表达。用特异性抑制剂SB203580抑制p38 MAPK，可消除ESAT-6介导的Prdx-1表达诱导以及NRF-2的磷酸化，且呈时间依赖性。在J774 A.1细胞中用特异性小干扰RNA（siRNA）抑制Prdx-1表达，导致分枝杆菌的细菌摄取和细胞内存活减少。这是首次报道ESAT-6调节Prdx-1，而Prdx-1参与分枝杆菌摄取和存活的增加。中间机制涉及通过p38和NRF-2依赖性信号激活，巨噬细胞中Prdx-1产生增加。
