Role of amylopectin granules in chronic toxoplasmosis, an HIV-AIDS defining infection

支链淀粉颗粒在慢性弓形体病（一种 HIV-AIDS 感染）中的作用

• 批准号: 10025481
• 负责人: ANTHONY P. SINAI
• 金额: $ 19.13万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-03-05 至 2022-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10025481
• 关键词: Acquired Immunodeficiency Syndrome; Acute; Address; Amylopectin; Anabolism; Apicomplexa; Biochemical; Biochemistry; Biological; Biology; Characteristics; Charge; Chemicals; Chronic; Chronic Phase; Clinical; Cyst; Cytoplasmic Granules; Development; Disease; Energy-Generating Resources; Enzymes; Event; Future; Genome; Glucans; Glucose; Glucose-6-Phosphate; Glutamine; Glycogen; Glycogen (Starch) Synthase; Growth; HIV; Human; Immune system; Immunosuppression; Individual; Infection; Kinetics; Knock-out; Laboratories; Length; Link; Location; Maintenance; Mediating; Metabolism; Morphology; Parasites; Parasitic infection; Pharmaceutical Preparations; Phase; Phosphorylation; Physiological; Plants; Play; Polymers; Population; Process; Production; Publishing; Regulation; Resources; Role; Signal Transduction; Starch; Testing; Therapeutic Intervention; Tissues; Toxoplasma; Toxoplasma gondii; Toxoplasmosis; Uridine Diphosphate Sugars; Work; acute infection; asexual; chronic infection; crystallinity; glucose 1 phosphate; imaging approach; in vivo; insight; knock-down; metabolomics; mutant; novel; quantitative imaging; sugar nucleotide; tool; transmission process

Project Summary A distinguishing characteristic of tissue cyst forming Apicomplexa, like Toxoplasma gondii, is the accumulation of amylopectin (starch) granules (AG) within bradyzoites and their absence within the actively growing tachyzoite forms. As polymers of glucose, AG functions as a battery serving as a reserve for energy production and biosynthetic functions. Our recent work established that bradyzoites retain significant replicative potential within tissue cysts in vivo. Notably, most bradyzoite replication within tissue cysts occurs asynchronously with clustered bursts of growth interceded with non-replicative periods. While the specific signals triggering these bursts remain unknown, what is clear is that they would require substantial energy and metabolite inputs to execute. Historical evidence and our findings reveal that AG levels within encysted bradyzoites are highly variable with clusters of parasites lacking AGs adjacent to others that are loaded with starch. This suggests that AG metabolism involving both synthesis and turnover are active within tissue cysts and may play a central role in the progression of chronic toxoplasmosis. We will directly address the dynamics and biological contributions of AGs in the progression of the chronic infection at the level of individual bradyzoites using novel tools and concepts developed in our recently published work. The variable levels of AG, within encysted bradyzoites, suggest that both AG accumulation and depletion are under regulatory control. Indeed the enzymatic machinery required for both the synthesis and regulated turnover of starch are encoded in the Toxoplasma genome. We will directly test the importance of AG in the acute infection, the regulation of stage conversion and the establishment/ progression of the chronic infection by targeting the commitment enzyme for starch synthesis, the UDP-glucose pyrophosphorylase (TgUDP-GPP, TgME49_218200), and the starch synthase (TgSS, TgME49_222800). Recent evidence suggests that despite being morphologically (though not biochemically) detectable, amylopectin may play a role in tachyzoite intermediary metabolism as well. In addition, the contribution of AG's to reactivation, the primary trigger of symptomatic disease in HIV-AIDS will be addressed in the context of induced immune suppression. With the proposed studies we aim to dissect the previously unexplored role of AG in tachyzoites, as factors in tachyzoite to bradyzoite conversion, the progression of the chronic infection and clinically critical reactivation in vivo. These studies will establish the groundwork for targeting AG metabolism for therapeutic intervention in the chronic infection where the paucity of effective drugs remains a significant issue in the clinical context of HIV-AIDS.

项目摘要 形成顶复体的组织囊肿的一个显著特征，如刚地弓形虫，是积累 支链淀粉（淀粉）颗粒（AG）内缓殖子和他们的缺乏内积极增长 速殖子形成。作为葡萄糖的聚合物，AG用作电池，作为能量生产的储备 和生物合成功能。我们最近的工作表明缓殖子保留了重要的复制潜力 在体内的组织囊肿内。值得注意的是，大多数缓殖子在组织囊肿内的复制是异步发生的， 在非复制期的中间，出现了成群的生长爆发。虽然触发这些的特定信号 爆发仍然是未知的，但清楚的是，它们需要大量的能量和代谢物输入， 执行.历史证据和我们的研究结果表明，在成囊的缓殖子内AG水平很高， 可变的是缺乏AG的寄生虫簇与负载淀粉的其它寄生虫相邻。这表明 AG代谢包括合成和周转，在组织囊肿内活跃， 在慢性弓形虫病进展中的作用。我们将直接解决动态和生物 使用新的方法，在个体缓殖子水平上，AGs在慢性感染进展中的作用 我们最近发表的工作中开发的工具和概念。囊内AG的可变水平 缓殖子，表明AG积累和消耗都在调节控制之下。确实 淀粉的合成和调节周转所需的酶机制编码在 弓形虫基因组。我们将直接测试AG在急性感染中的重要性， 转化和慢性感染的建立/进展， 淀粉合成、UDP-葡萄糖焦磷酸化酶（TgUDP-GPP，TgME49_218200）和淀粉 合成酶（TgSS，TgME49_222800）。最近的证据表明，尽管在形态上（虽然不是）， 虽然支链淀粉在生物化学上是可检测的，但是支链淀粉也可能在速殖子中间代谢中起作用。在 此外，AG对重新激活的贡献，即HIV-艾滋病症状性疾病的主要触发因素， 在诱导免疫抑制的背景下解决。通过拟议的研究，我们的目标是剖析 AG在速殖子中以前未探索的作用，作为速殖子向缓殖子转化的因素， 慢性感染的进展和临床上严重的体内再活化。这些研究将建立 为针对AG代谢进行治疗干预的慢性感染奠定基础 有效药物的缺乏仍然是临床上艾滋病毒/艾滋病的一个重要问题。