Toxoplasma Uses GRA16 To Upregulate Host c-Myc.
Toxoplasma Uses GRA16 To Upregulate Host c-Myc.
复制标题
弓形虫利用 GRA16 上调宿主 c-Myc。
DOI：
10.1128/msphere.00402-20
复制
发表时间：
2020
期刊：
影响因子：
4.8
通讯作者：
Boothroyd,JohnC
中科院分区：
文献类型：
--
作者：
Panas,MichaelW;Boothroyd,JohnC
对宿主细胞的操纵是许多细胞内生物生命的关键部分。我们最近开始认识到，细胞内病原体弓形虫（Toxoplasma gondii）对其宿主细胞进行重编程的程度，这可以通过中央调节因子c-Myc（一种协调无数细胞功能的癌基因）的显著上调来说明。为了鉴定能够调节c-Myc的效应蛋白，我们的实验室构建了一个筛选不能实现这种上调的突变寄生虫的方法。有趣的是，该筛选鉴定了位于寄生虫空泡膜中/上的复合物的许多组分，该复合物是将弓形虫蛋白质转运到宿主细胞质中所必需的，但从未鉴定出特定的效应蛋白。因此，寄生虫如何上调c-Myc在很大程度上是一个谜。以前，弓形虫致密颗粒蛋白GRA 16被描述为与PP 2A-B的一种同种型结合，PP 2A-B是协调催化蛋白磷酸酶PP 2A活性的调节亚基。由于已报道其他PP 2A亚基将PP 2A蛋白磷酸酶活性靶向c-Myc，随后导致c-Myc不稳定，因此我们检查了GRA 16是否对宿主c-Myc积累有影响。弓形虫GRA 16蛋白在犬新孢子虫中的表达，赋予了新孢子虫现在这样做的能力，犬新孢子虫是弓形虫的近亲，它不能自然地上调宿主c-Myc。进一步的支持是通过从弓形虫中删除GRA 16基因并观察到弓形虫achyzoites上调宿主c-Myc的能力严重减弱而获得的。因此，GRA 16是弓形虫上调宿主c-Myc的能力的核心效应蛋白。重要信息原癌基因c-Myc在许多动物细胞的生长和分裂中起着至关重要的作用。以往的研究已经确定了一个积极的上调c-Myc的弓形虫，表明存在一个或多个出口的“效应”蛋白。然而，这种效应器的身份以前并不知道。在这里，我们表明，以前已知的分泌蛋白，GRA 16，在c-Myc上调中起着至关重要的作用。这一发现将使进一步解剖弓形虫感染细胞中c-Myc上调的确切机制和作用成为可能。
Manipulation of the host cell is a crucial part of life for many intracellular organisms. We have recently come to appreciate the extent to which the intracellular pathogen Toxoplasma gondii reprograms its host cell, and this is illustrated by the marked upregulation of the central regulator c-Myc, an oncogene that coordinates myriad cellular functions. In an effort to identify an effector protein capable of regulating c-Myc, our laboratory constructed a screen for mutant parasites unable to accomplish this upregulation. Interestingly, this screen identified numerous components of a complex located in/on the parasitophorous vacuole membrane necessary to translocateToxoplasmaproteins out into the host cytosol, but it never identified a specific effector protein. Thus, how the parasite upregulates c-Myc has largely been a mystery. Previously, theToxoplasmadense granule protein GRA16 has been described to bind to one isoform of PP2A-B, a regulatory subunit that coordinates the activity of the catalytic protein phosphatase PP2A. As other PP2A subunits have been reported to target PP2A protein phosphatase activity to c-Myc, subsequently leading to c-Myc destabilization, we examined whether GRA16 has an impact on host c-Myc accumulation. Expression ofToxoplasma’s GRA16 protein in Neospora caninum, a close relative ofToxoplasmathat does not naturally upregulate host c-Myc, conferred the ability onNeosporato do this now. Further support was obtained by deleting theGRA16gene fromToxoplasmaand observing a severely diminished ability ofToxoplasmatachyzoites to upregulate host c-Myc. Thus, GRA16 is an effector protein central toToxoplasma’s ability to upregulate host c-Myc.IMPORTANCEThe proto-oncogene c-Mycplays a crucial role in the growth and division of many animal cells. Previous studies have identified an active upregulation of c-Myc byToxoplasmatachyzoites, suggesting the existence of one or more exported “effector” proteins. The identity of such an effector, however, has not previously been known. Here, we show that a previously known secreted protein, GRA16, plays a crucial role in c-Myc upregulation. This finding will enable further dissection of the precise mechanism and role of c-Myc upregulation inToxoplasma-infected cells.