Crosstalk between PKA and PKG controls pH-dependent host cell egress of Toxoplasma gondii
Crosstalk between PKA and PKG controls pH-dependent host cell egress of Toxoplasma gondii
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DOI：
10.15252/embj.201796794
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发表时间：
2017-11-02
期刊：
影响因子：
11.4
通讯作者：
Soldati-Favre, Dominique
中科院分区：
文献类型：
--
作者：
Jia, Yonggen;Marq, Jean-Baptiste;Soldati-Favre, Dominique
弓形虫编码三个蛋白激酶A催化亚基（PKAc 1 -3）和一个调节亚基（PKAr），以整合cAMP依赖的信号。在这里，我们表明，非活性PKAc 1维持在寄生虫的表膜与酰化PKAr 1无论是有条件的敲除PKAr或PKAc 1的过表达块寄生虫分裂。相反，PKAc 1的下调或不结合cAMP的显性阴性PKAr亚型的稳定触发寄生虫从感染细胞中过早排出，随后是导致宿主细胞裂解的连续入侵尝试。这种不合时宜的排出依赖于宿主细胞的酸化。磷酸化蛋白质组分析表明cAMP和cGMP信号之间的相互作用，PKAc 1失活改变了一个假定的cGMP-磷酸二酯酶的磷酸化概况。与此一致，对cGMP依赖性蛋白激酶G（PKG）的抑制可以阻止PKAc 1失活或环境酸化诱导的逸出，而cGMP磷酸二酯酶抑制剂可以避免PKAc 1或pH中和引起的逸出抑制。这表明pH和PKAc 1作为cGMP代谢的平衡调节剂来控制排出。这些结果揭示了PKA和PKG通路之间的串扰，以控制T。刚地。
Toxoplasma gondii encodes three protein kinase A catalytic (PKAc1-3) and one regulatory (PKAr) subunits to integrate cAMP-dependent signals. Here, we show that inactive PKAc1 is maintained at the parasite pellicle by interacting with acylated PKAr1 Either a conditional knockdown of PKAr or the overexpression of PKAc1 blocks parasite division. Conversely, down-regulation of PKAc1 or stabilisation of a dominant-negative PKAr isoform that does not bind cAMP triggers premature parasite egress from infected cells followed by serial invasion attempts leading to host cell lysis. This untimely egress depends on host cell acidification. A phosphoproteome analysis suggested the interplay between cAMP and cGMP signalling as PKAc1 inactivation changes the phosphorylation profile of a putative cGMP-phosphodiesterase. Concordantly, inhibition of the cGMP-dependent protein kinase G (PKG) blocks egress induced by PKAc1 inactivation or environmental acidification, while a cGMP-phosphodiesterase inhibitor circumvents egress repression by PKAc1 or pH neutralisation. This indicates that pH and PKAc1 act as balancing regulators of cGMP metabolism to control egress. These results reveal a crosstalk between PKA and PKG pathways to govern egress in T. gondii.