Activation of Mechanistic Target of Rapamycin (mTOR) in Human Endothelial Cells Infected with Pathogenic Spotted Fever Group Rickettsiae.
Activation of Mechanistic Target of Rapamycin (mTOR) in Human Endothelial Cells Infected with Pathogenic Spotted Fever Group Rickettsiae.
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DOI：
10.3390/ijms21197179
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发表时间：
2020-09-29
影响因子：
5.6
通讯作者：
Sahni SK
中科院分区：
文献类型：
--
作者：
Sahni A;Narra HP;Sahni SK
由于宿主血管内层微血管内皮的趋向性，血管炎症和功能障碍是立克次体发病机制的显著特征，然而，作为感染主要靶点的病原体与宿主内皮细胞（ECs）相互作用的基本重要细节仍然知之甚少。雷帕霉素的机制靶点（mTOR）是磷脂酰肌醇激酶相关激酶家族的一种丝氨酸/苏氨酸蛋白激酶，可组装成两个功能不同的复合物，即mTORC1 （Raptor）和mTORC2 (Rictor)，通过转录调控参与决定细胞内病原体的先天免疫反应。在本研究中，我们研究了mTOR的激活状态及其在立克次体和conorii感染期间对宿主EC反应的潜在贡献。对感染ec的蛋白裂解物进行分析，以确定p70 S6激酶（p70 S6K）的苏氨酸421/丝氨酸424磷酸化，以及mTOR本身丝氨酸2448的磷酸化，作为mTORC1激活的既定标记。对于mTORC2，我们分别评估了蛋白激酶B （PKB或Akt）和蛋白激酶C （PKC）在丝氨酸473和丝氨酸657上的磷酸化。结果表明，在ECs立克次体感染期间，p70 S6K和mTOR的磷酸化早在感染后3小时就增加了，并持续到感染后24小时。磷酸化akt和磷酸化pkc的稳态水平也升高。致病性立克次体感染也导致微管相关蛋白1A/ 1b -轻链3 （LC3-II）点的形成和LC3-II脂化增加，通过将靶向mTORC1的siRNA引入ECs可显著抑制这一反应。因此，这些发现为体外立克次体EC感染期间mTORC1和mTORC2的激活提供了第一个证据，并表明响应细胞内感染的早期自噬诱导可能受到这一重要途径的调节，该途径被认为是细胞免疫和炎症的中心整合器。
Attributed to the tropism for host microvascular endothelium lining the blood vessels, vascular inflammation and dysfunction represent salient features of rickettsial pathogenesis, yet the details of fundamentally important pathogen interactions with host endothelial cells (ECs) as the primary targets of infection remain poorly appreciated. Mechanistic target of rapamycin (mTOR), a serine/threonine protein kinase of the phosphatidylinositol kinase-related kinase family, assembles into two functionally distinct complexes, namely mTORC1 (Raptor) and mTORC2 (Rictor), implicated in the determination of innate immune responses to intracellular pathogens via transcriptional regulation. In the present study, we investigated activation status of mTOR and its potential contributions to host EC responses during Rickettsia rickettsii and R. conorii infection. Protein lysates from infected ECs were analyzed for threonine 421/serine 424 phosphorylation of p70 S6 kinase (p70 S6K) and that of serine 2448 on mTOR itself as established markers of mTORC1 activation. For mTORC2, we assessed phosphorylation of protein kinase B (PKB or Akt) and protein kinase C (PKC), respectively, on serine 473 and serine 657. The results suggest increased phosphorylation of p70 S6K and mTOR during Rickettsia infection of ECs as early as 3 h and persisting for up to 24 h post-infection. The steady-state levels of phospho-Akt and phospho-PKC were also increased. Infection with pathogenic rickettsiae also resulted in the formation of microtubule-associated protein 1A/1B-light chain 3 (LC3-II) puncta and increased lipidation of LC3-II, a response significantly inhibited by introduction of siRNA targeting mTORC1 into ECs. These findings thus yield first evidence for the activation of both mTORC1 and mTORC2 during EC infection in vitro with Rickettsia species and suggest that early induction of autophagy in response to intracellular infection might be regulated by this important pathway known to function as a central integrator of cellular immunity and inflammation.
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影响因子：
32.4
作者：
Blanchet FP;Moris A;Nikolic DS;Lehmann M;Cardinaud S;Stalder R;Garcia E;Dinkins C;Leuba F;Wu L;Schwartz O;Deretic V;Piguet V
通讯作者：
Piguet V
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4.7
作者：
Liko, Dritan;Hall, Michael N.
通讯作者：
Hall, Michael N.
影响因子：
29.7
作者：
Powell JD;Pollizzi KN;Heikamp EB;Horton MR
通讯作者：
Horton MR
影响因子：
6.7
作者：
Lu, Richard;Herrera, Bobby Brooke;Goldberg, Marcia B.
通讯作者：
Goldberg, Marcia B.
影响因子：
3.1
作者：
Lina, Taslima T.;Luo, Tian;McBride, Jere W.
通讯作者：
McBride, Jere W.