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

基本信息

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
项目类别：
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

项目摘要

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.

项目概要形成顶复合体的组织囊肿的一个显着特征，如弓形虫，是积累缓殖子内的支链淀粉（淀粉）颗粒（AG）及其在活跃生长的细胞中的缺失速殖子形成。作为葡萄糖的聚合物，AG 充当电池，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显着的复制潜力体内组织囊肿内。值得注意的是，组织包囊内的大多数缓殖子复制与聚集的爆发性增长与非复制期相协调。虽然触发这些的具体信号爆发仍然未知，但明确的是它们需要大量的能量和代谢输入执行。历史证据和我们的研究结果表明，包囊缓殖子内的 AG 水平非常高缺乏 AG 的寄生虫簇与其他富含淀粉的寄生虫簇相邻。这表明涉及合成和周转的 AG 代谢在组织囊肿内很活跃，并且可能发挥核心作用在慢性弓形虫病的进展中的作用。我们将直接解决动力学和生物学问题 AGs 在个体缓殖子水平上的慢性感染进展中的贡献我们最近发表的工作中开发的工具和概念。包囊内 AG 的可变水平缓殖子表明 AG 的积累和消耗都受到监管控制。确实是淀粉合成和调节周转所需的酶机械被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，阶段的调节通过靶向定型酶来实现慢性感染的转化和建立/进展淀粉合成、UDP-葡萄糖焦磷酸化酶（TgUDP-GPP、TgME49_218200）和淀粉合酶（TgSS、TgME49_222800）。最近的证据表明，尽管在形态上（尽管不是）生物化学上可检测到，支链淀粉也可能在速殖子中间代谢中发挥作用。在此外，AG 对重新激活（HIV-AIDS 中症状性疾病的主要触发因素）的贡献将是在诱导免疫抑制的背景下解决。通过拟议的研究，我们的目的是剖析 AG 在速殖子中的作用之前未被探索过，作为速殖子向缓殖子转化的因素，慢性感染的进展和临床关键的体内再激活。这些研究将建立针对 AG 代谢进行治疗干预的基础，其中缺乏在艾滋病毒/艾滋病的临床背景下，有效药物的选择仍然是一个重要问题。