Identification of Signaling Pathways by Which CD40 Stimulates Autophagy and Antimicrobial Activity against Toxoplasma gondii in Macrophages
Identification of Signaling Pathways by Which CD40 Stimulates Autophagy and Antimicrobial Activity against Toxoplasma gondii in Macrophages
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DOI：
10.1128/iai.00101-16
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发表时间：
2016-09-01
影响因子：
3.1
通讯作者：
Subauste, Carlos S.
中科院分区：
文献类型：
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作者：
Liu, Elizabeth;Corcino, Yalitza Lopez;Subauste, Carlos S.
CD 40是弓形虫在宿主细胞内自噬和自噬杀伤的重要刺激因子。与营养剥夺或模式识别受体诱导的自噬相反，细胞介导的免疫对Beclin 1和ULK 1（自噬的关键调节因子）的影响知之甚少。在这里，我们研究了CD 40刺激巨噬细胞自噬的分子机制。CD 40连接引起双相Jun N-末端蛋白激酶（JNK）磷酸化。JNK磷酸化的第二阶段依赖于肿瘤坏死因子α（TNF-α）的自分泌产生。TNF-α和JNK信号传导是CD 40诱导的自噬增加所必需的。CD 40下游的JNK信号传导导致Bcl-2的Ser-87磷酸化以及Bcl-2和Beclin 1之间的解离，这是已知刺激Beclin 1的自噬功能的事件。然而，单独的TNF-α不能刺激自噬。CD 40还通过包括钙/钙调蛋白依赖性激酶β（CaMKK β）、AMP活化蛋白激酶（AMPK）和ULK 1的途径刺激自噬。CD 40在其活化位点Thr-172引起AMPK磷酸化。这种作用由CaMKK β介导，并且不受TNF-α中和的影响。CD 40触发ULK 1的AMPK依赖性Ser-555磷酸化。CaMKK β、AMPK和ULK 1是CD 40诱导的自噬增加所必需的。已知CD 40介导的弓形虫自噬杀伤需要TNF-α。JNK、CaMKK β、AMPK或ULK 1的敲低阻止了T. CD 40激活的巨噬细胞中的弓形虫杀伤。JNK磷酸化-Bcl-2磷酸化-Bcl-2-Beclin 1解离和AMPK磷酸化-ULK 1磷酸化的第二阶段同时发生，与CD 40刺激后4 h相似。因此，CaMKK β和TNF-α是上游分子，CD 40通过其作用于ULK 1和Beclin 1以刺激自噬和T细胞杀伤。刚地。
CD40 is an important stimulator of autophagy and autophagic killing of Toxoplasma gondii in host cells. In contrast to autophagy induced by nutrient deprivation or pattern recognition receptors, less is known about the effects of cell-mediated immunity on Beclin 1 and ULK1, key regulators of autophagy. Here we studied the molecular mechanisms by which CD40 stimulates autophagy in macrophages. CD40 ligation caused biphasic Jun N-terminal protein kinase (JNK) phosphorylation. The second phase of JNK phosphorylation was dependent on autocrine production of tumor necrosis factor alpha (TNF-alpha). TNF-alpha and JNK signaling were required for the CD40-induced increase in autophagy. JNK signaling downstream of CD40 caused Ser-87 phosphorylation of Bcl-2 and dissociation between Bcl-2 and Beclin 1, an event known to stimulate the autophagic function of Beclin 1. However, TNF-alpha alone was unable to stimulate autophagy. CD40 also stimulated autophagy via a pathway that included calcium/calmodulin-dependent kinase kinase beta (CaMKK beta), AMP-activated protein kinase (AMPK), and ULK1. CD40 caused AMPK phosphorylation at its activating site, Thr-172. This effect was mediated by CaMKK beta and was not impaired by neutralization of TNF-alpha. CD40 triggered AMPK-dependent Ser-555 phosphorylation of ULK1. CaMKK beta, AMPK, and ULK1 were required for CD40-induced increase in autophagy. CD40-mediated autophagic killing of Toxoplasma gondii is known to require TNF-alpha. Knockdown of JNK, CaMKK beta, AMPK, or ULK1 prevented T. gondii killing in CD40-activated macrophages. The second phase of JNK phosphorylation-Bcl-2 phosphorylation-Bcl-2-Beclin 1 dissociation and AMPK phosphorylation-ULK1 phosphorylation occurred simultaneously at similar to 4 h post-CD40 stimulation. Thus, CaMKK beta and TNF-alpha are upstream molecules by which CD40 acts on ULK1 and Beclin 1 to stimulate autophagy and killing of T. gondii.