Department of Biotechnology, Motilal Nehru National Institute of Technology Allahabad, Prayagraj, Uttar Pradesh 211004, India.
Department of Biotechnology, Motilal Nehru National Institute of Technology Allahabad, Prayagraj, Uttar Pradesh 211004, India.
Cell Signal. 2022 Nov;99:110441. doi: 10.1016/j.cellsig.2022.110441. Epub 2022 Aug 20.
N-(3-oxododecanoyl) homoserine lactone (3oc) is a Pseudomonas aeruginosa secreted quorum-sensing signal molecule playing a crucial role in regulating quorum-sensing (QS) dependent biofilm formation and secretion of virulence factors. In addition to regulating quorum sensing, 3oc also plays an immunomodulatory role in the host by triggering regulated cell death in immune cells. The molecular mechanisms of 3oc in modulating macrophage pathologies are still unclear. In this study, we hypothesized the novel 3oc mediated crosstalk between autophagy and apoptosis at the interphase of calcium signaling in human macrophages. The study showed that 3oc induces mitochondrial dysfunction and apoptosis in macrophages through elevating cytosolic Ca ([Ca]) levels. Pre-treatment with the calcium-specific chelator BAPTA-AM effectively abrogated 3oc-induced apoptotic events, like mitochondrial ROS generation (mROS), mitochondrial membrane potential (MMP) drop, and phosphatidylserine (PS) exposure. The study also showed that 3oc induces autophagy, as assessed by the accumulation of autophagic vacuoles, induction of lysosomal biogenesis, upregulation of autophagy genes (LC3, BECLIN 1, STX17, PINK1, and TFEB), autophagosomes formation, and LC3 lipidation. Mechanistically, our study proved that 3oc-induced autophagy was [Ca] dependent as BAPTA-AM pre-treatment reduced autophagosome formation. Furthermore, inhibiting autophagy with chloroquine attenuated 3oc-induced apoptosis, while autophagy induction with rapamycin aggravated cell death, suggesting autophagy plays a role in cell death in 3oc-treated macrophages. In conclusion, our findings indicate that 3oc activates a multifaceted death signaling by activating autophagy and apoptosis through Ca signaling, and we propose pharmacological modulation of Ca signaling may act as a combinatorial therapeutic intervention in patients with Pseudomonas aeruginosa-associated infections.
N-(3-氧代十二烷酰基)高丝氨酸内酯 (3oc) 是铜绿假单胞菌分泌的群体感应信号分子，在调节群体感应 (QS) 依赖性生物膜形成和毒力因子分泌中起着关键作用。除了调节群体感应外，3oc 还通过触发免疫细胞中受调控的细胞死亡，在宿主中发挥免疫调节作用。3oc 调节巨噬细胞病理学的分子机制尚不清楚。在这项研究中，我们假设在人类巨噬细胞钙信号的交界区，3oc 通过调控自噬和细胞凋亡之间的新型串扰来调节巨噬细胞。研究表明，3oc 通过升高胞质 Ca([Ca])水平诱导巨噬细胞线粒体功能障碍和细胞凋亡。用钙特异性螯合剂 BAPTA-AM 预处理可有效阻断 3oc 诱导的细胞凋亡事件，如线粒体 ROS 生成 (mROS)、线粒体膜电位 (MMP) 下降和磷脂酰丝氨酸 (PS) 暴露。研究还表明，3oc 诱导自噬，如自噬小体的积累、溶酶体生物发生的诱导、自噬基因 (LC3、BECLIN 1、STX17、PINK1 和 TFEB) 的上调、自噬体的形成和 LC3 脂质化。从机制上讲，我们的研究证明 3oc 诱导的自噬依赖于[Ca]，因为 BAPTA-AM 预处理减少了自噬体的形成。此外，用氯喹抑制自噬可减弱 3oc 诱导的细胞凋亡，而用雷帕霉素诱导自噬则加重细胞死亡，表明自噬在 3oc 处理的巨噬细胞中死亡中发挥作用。总之，我们的研究结果表明，3oc 通过钙信号激活自噬和细胞凋亡，从而激活多效性死亡信号，我们提出的钙信号药理学调节可能作为铜绿假单胞菌相关感染患者的联合治疗干预措施。
