The Role of Glutamine Metabolism for P. gingivalis-Induced Non-Canonical Autophagy in Epithelial Cells

越来越多的证据表明，谷氨酰胺（Gln）代谢可以影响关键的代谢和自噬 细胞事件牙龈卟啉单胞菌（Porphyromonas gingivalis，P.g）是一种主要的牙周病、苛养菌、致病菌， 牙龈粘膜的成功定植者，最近已被确定为诱导一种特殊形式的 人牙龈上皮细胞（GECs）中的自噬。虽然GEC在本质上是重要的第一线， 牙龈的免疫防御，GECs可以被P.g利用，以确保成功的持久性生态位， 口腔粘膜和潜在的全身传播途径。尽管越来越多的证据表明 改变的谷氨酰胺代谢可导致细胞病理学，关于宿主谷氨酰胺 代谢可能受到细菌的影响，以调节宿主的氧化还原稳态，并可能促进 GEC中的细菌存活。最近，我们发现P.g稳定地增加鲁棒性谷胱甘肽（GSH） GECs中的生产，以对抗宿主介导的氧化应激驱动的病原体清除。我们的新发现， 首次表明，P.g感染改变宿主谷氨酰胺代谢，谷胱甘肽合成的一个组成部分，在GECs。 此外，我们最近证明，P.g诱导GEC中的亲细菌形式的自噬， 富含内质网（ER）/微管相关蛋白1A/1B-轻链3（LC 3）双膜 自噬体作为P.g的复制小生境并保护细菌免受抗菌剂降解 途径。我们的新数据表明，这些含P. g 自噬体依赖于关键的氧化还原分子，谷胱甘肽过氧化物酶1（GpX 1）。的 对GpX 1的依赖性可通过增加GEC细胞环境中的游离Gln水平而显著改变。 因此，我们对这一提议的总体假设是，P.g改变GEC中宿主Gln代谢， 维持宿主的氧化还原稳态，并特别有助于GpX 1驱动的，亲细菌的 自噬的形式。提出了两个具体目标来检验这一假设。目标1将描述 在P.g感染期间发生的与宿主细胞Gln特异性相关的表型分子事件 代谢和宿主细胞的氧化还原状态，允许P.g在GEC中的细胞内存活。目标2将 机械地确定参与P. g诱导的自噬的分子相互作用组， GEC中宿主Gln代谢的调节。这些共同将确定哪些元素的谷氨酰胺代谢 途径对于GECs中P.g的自噬存活至关重要，并将阐明GECs中P.g的特异性分子生物学机制。 在P.g感染后，由宿主Gln代谢的变化驱动的参与促细菌自噬的机制。 总的来说，这项建议将有助于确定新的靶向治疗策略，以控制 P.g在口腔粘膜及更远处的慢性细胞内定殖。获得F31奖学金 建议将进一步申请人的研究目标，关键有助于她在口语领域的培训 生物学，并将促进她作为一个口腔健康学术科学家的独特发展。

Growing evidence underlines that Glutamine (Gln) metabolism can influence key metabolic and autophagic cellular events. Porphyromonas gingivalis (P.g) is a major periodontopathic, fastidious, pathobiont and successful colonizer of gingival mucosa, which has recently been identified to induce a special form of autophagy in human gingival epithelial cells (GECs). While GECs function as an intrinsically important first line of immune defense of the gingiva, GECs can be exploited by P.g for securing a successful persistence niche in the oral mucosa and a potential systemic dissemination route. Despite the growing evidence pinpointing that altered Gln metabolism can contribute to cellular pathologies, knowledge gaps remain regarding how host Gln metabolism could be influenced by bacteria to regulate host redox homeostasis and potentially promote bacterial survival in the GECs. Recently, we discovered that P.g steadily increases robust Glutathione (GSH) production in GECs to combat host-mediated oxidative stress-driven pathogen clearance. Our novel findings, for the first time, show that P.g infection alters host Gln metabolism, a component of GSH synthesis, in GECs. In addition, we recently demonstrated that P.g induces a pro-bacterial form of autophagy in GECs, where Endoplasmic Reticulum-rich (ER)/Microtubule-associated protein 1A/1B-light chain 3 (LC3) double membrane autophagosomes act as replicative niches for P.g and protect the bacteria from antimicrobial degradation pathways. Our novel data shows that the biogenesis and maintenance of these P.g-containing autophagosomes is dependent on the critical redox molecule, Glutathione Peroxidase 1 (GpX1). The dependency on GpX1 can be markedly altered by increasing free Gln levels in GECs' cellular environment. Thus, our overarching hypothesis for this proposal is that P.g alters host Gln metabolism in GECs to maintain host redox homeostasis and specifically contributes to the biogenesis of a GpX1-driven, pro-bacterial form of autophagy. Two Specific Aims are proposed to test this hypothesis. Aim 1 will characterize the phenotypic molecular events occurring during P.g infection that specifically associate with host cell Gln metabolism and the host cell redox state, allowing for the intracellular survival of P.g in GECs. Aim 2 will mechanistically determine the molecular interactome involved in P.g-induced autophagy through the modulation of host Gln metabolism in GECs. These collectively will identify what elements of the Gln metabolic pathways are critical for the autophagic survival of P.g in GECs, and will elucidate the specific molecular machineries involved in pro-bacterial autophagy driven by changes in host Gln metabolism upon P.g infection. Overall, this proposal will contribute to the identification of novel targeted therapeutic strategies to control the chronic intracellular colonization of P.g in the oral mucosa and beyond. Receiving the F31 Fellowship for this proposal will further the applicant's research goals, critically contribute to her training in the field of Oral Biology, and will foster her unique development as an oral health academic scientist.