Effects of PERK eIF2α Kinase Inhibitor against Toxoplasma gondii
Effects of PERK eIF2α Kinase Inhibitor against Toxoplasma gondii
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DOI：
10.1128/aac.01442-18
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发表时间：
2018-11-01
影响因子：
4.9
通讯作者：
Sullivan, William J., Jr.
中科院分区：
文献类型：
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作者：
Augusto, Leonardo;Martynowicz, Jennifer;Sullivan, William J., Jr.
弓形虫是一种专性细胞内寄生虫，已感染三分之一的人口。在感染温血脊椎动物后，寄生虫的复制形式（速殖子）转化为存在于组织包囊中的潜伏形式（缓殖子）。在免疫缺陷期间，缓殖子可再转化为速殖子并引起危及生命的弓形虫病。我们以前报道过通过T细胞α亚基的磷酸化进行翻译控制。弓形虫真核起始因子2（eIF 2 α）（TgIF 2 α）是寄生虫应激反应的关键组分。不同的应激可以诱导速殖子向缓殖子转化，包括那些破坏寄生虫内质网（ER）的应激（ER应激）。弓形虫具有四种eIF 2 α激酶，其中一种（TgIF 2K-A）定位于寄生虫ER，类似于蛋白激酶R样内质网激酶（PERK），eIF 2 α激酶在哺乳动物细胞中响应ER应激。在这里，我们研究了PERK抑制剂（PERKi）对弓形虫的影响。我们的结果表明，PERKi GSK 2606414阻断TgIF 2 K-A的酶活性，并特异性地降低响应ER应激的TgIF 2 α磷酸化。PERKi还显著阻碍了速殖子溶解周期的多个步骤，并显著降低了体外缓殖子分化的频率。在感染前用PERKi预处理宿主细胞不影响寄生虫感染性，并且PERKi仍然损害缺乏PERK的宿主细胞中的寄生虫复制。在小鼠中，PERKi赋予适度的保护免受致死剂量的弓形虫。我们的研究结果代表了支持TgIF 2K-A作为治疗弓形虫病的有吸引力的新靶点的第一个药理学证据。
Toxoplasma gondii is an obligate intracellular parasite that has infected one-third of the population. Upon infection of warm-blooded vertebrates, the replicating form of the parasite (tachyzoite) converts into a latent form (bradyzoite) present in tissue cysts. During immune deficiency, bradyzoites can reconvert into tachyzoites and cause life-threatening toxoplasmosis. We previously reported that translational control through phosphorylation of the alpha subunit of T. gondii eukaryotic initiation factor 2 (eIF2 alpha) (TgIF2 alpha) is a critical component of the parasite stress response. Diverse stresses can induce the conversion of tachyzoites to bradyzoites, including those disrupting the parasite's endoplasmic reticulum (ER) (ER stress). Toxoplasma possesses four eIF2 alpha kinases, one of which (TgIF2K-A) localizes to the parasite ER analogously to protein kinase R-like endoplasmic reticulum kinase (PERK), the eIF2 alpha kinase that responds to ER stress in mammalian cells. Here, we investigated the effects of a PERK inhibitor (PERKi) on Toxoplasma Our results show that the PERKi GSK2606414 blocks the enzymatic activity of TgIF2K-A and reduces TgIF2 alpha phosphorylation specifically in response to ER stress. PERKi also significantly impeded multiple steps of the tachyzoite lytic cycle and sharply lowered the frequency of bradyzoite differentiation in vitro Pretreatment of host cells with PERKi prior to infection did not affect parasite infectivity, and PERKi still impaired parasite replication in host cells lacking PERK. In mice, PERKi conferred modest protection from a lethal dose of Toxoplasma Our findings represent the first pharmacological evidence supporting TgIF2K-A as an attractive new target for the treatment of toxoplasmosis.