Knorr Jakob, Backert Steffen, Tegtmeyer Nicole
Eur J Microbiol Immunol (Bp). 2020 Mar 17;10(1):20-27. doi: 10.1556/1886.2020.00001. eCollection 2020 Apr 7.
The gastric pathogen colonizes approximately half of the human world population. The bacterium injects the effector protein cytotoxin associated gene A (CagA) via a type-IV secretion system into host epithelial cells, where the protein becomes phosphorylated at specific EPIYA-motifs by cellular kinases. Inside the host cell, CagA can interact with over 25 different proteins in both phosphorylation-dependent and phosphorylation-independent manners, resulting in manipulation of host-cell signaling pathways. During the course of an infection, certain host-cell proteins undergo tyrosine dephosphorylation in a CagA-dependent manner, including the actin-binding proteins cortactin and vinculin. A predominant response of intracellular CagA is the binding and activation of tyrosine phosphatase, the human Src-homology-region-2-domain-containing-phosphatase-2 (SHP2). Here, we considered the possibility that activated SHP2 might be responsible for the dephosphorylation of cortactin and vinculin. To investigate this, phosphatase inhibitor studies were performed. Additionally, a complete knockout mutant of SHP2 in AGS cells was created by CRISPR/Cas9 technology, and these cells were infected with However, neither the presence of an inhibitor nor the inactivation of SHP2 prevented the dephosphorylation of cortactin and vinculin upon CagA delivery. Tyrosine dephosphorylation of these proteins is therefore independent of SHP2 and instead must be caused by another, as yet unidentified, protein tyrosine phosphatase.
这种胃部病原体感染了全球约一半的人口。该细菌通过IV型分泌系统将效应蛋白细胞毒素相关基因A（CagA）注入宿主上皮细胞，在细胞内，该蛋白会被细胞激酶在特定的EPIYA基序处磷酸化。在宿主细胞内，CagA能够以磷酸化依赖和非依赖的方式与超过25种不同的蛋白质相互作用，从而操纵宿主细胞信号通路。在感染过程中，某些宿主细胞蛋白会以CagA依赖的方式发生酪氨酸去磷酸化，包括肌动蛋白结合蛋白皮层肌动蛋白和纽蛋白。细胞内CagA的一个主要反应是与含人类Src同源区2结构域的磷酸酶2（SHP2）结合并激活该酪氨酸磷酸酶。在此，我们考虑了激活的SHP2可能是皮层肌动蛋白和纽蛋白去磷酸化原因的可能性。为了对此进行研究，我们开展了磷酸酶抑制剂研究。此外，我们利用CRISPR/Cas9技术构建了AGS细胞中SHP2的完全敲除突变体，并用……感染了这些细胞。然而，无论是抑制剂的存在还是SHP2的失活，都不能阻止CagA导入后皮层肌动蛋白和纽蛋白的去磷酸化。因此，这些蛋白的酪氨酸去磷酸化与SHP2无关，而是必定由另一种尚未明确的蛋白酪氨酸磷酸酶引起。
