Vanrell María Cristina, Losinno Antonella Denisse, Cueto Juan Agustín, Balcazar Darío, Fraccaroli Laura Virginia, Carrillo Carolina, Romano Patricia Silvia
Laboratorio de Biología de Trypanosoma cruzi y la célula hospedadora. Instituto de Histología y Embriología (IHEM), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo-CONICET, Mendoza, Argentina.
Instituto de Ciencias y Tecnología Dr. César Milstein-CONICET; Buenos Aires, Argentina.
PLoS Negl Trop Dis. 2017 Nov 1;11(11):e0006049. doi: 10.1371/journal.pntd.0006049. eCollection 2017 Nov.
Autophagy is a cellular process required for the removal of aged organelles and cytosolic components through lysosomal degradation. All types of eukaryotic cells from yeasts to mammalian cells have the machinery to activate autophagy as a result of many physiological and pathological situations. The most frequent stimulus of autophagy is starvation and the result, in this case, is the fast generation of utilizable food (e.g. amino acids and basic nutrients) to maintain the vital biological processes. In some organisms, starvation also triggers other associated processes such as differentiation. The protozoan parasite Trypanosoma cruzi undergoes a series of differentiation processes throughout its complex life cycle. Although not all autophagic genes have been identified in the T. cruzi genome, previous works have demonstrated the presence of essential autophagic-related proteins. Under starvation conditions, TcAtg8, which is the parasite homolog of Atg8/LC3 in other organisms, is located in autophagosome-like vesicles. In this work, we have characterized the autophagic pathway during T. cruzi differentiation from the epimastigote to metacyclic trypomastigote form, a process called metacyclogenesis. We demonstrated that autophagy is stimulated during metacyclogenesis and that the induction of autophagy promotes this process. Moreover, with exception of bafilomycin, other classical autophagy modulators have similar effects on T. cruzi autophagy. We also showed that spermidine and related polyamines can positively regulate parasite autophagy and differentiation. We concluded that both polyamine metabolism and autophagy are key processes during T. cruzi metacyclogenesis that could be exploited as drug targets to avoid the parasite cycle progression.
自噬是一种细胞过程,通过溶酶体降解来清除衰老的细胞器和胞质成分。从酵母到哺乳动物细胞的所有类型真核细胞,由于许多生理和病理情况,都具备激活自噬的机制。自噬最常见的刺激因素是饥饿,在这种情况下,结果是快速产生可利用的食物(如氨基酸和基本营养物质)以维持重要的生物过程。在一些生物体中,饥饿还会触发其他相关过程,如分化。原生动物寄生虫克氏锥虫在其复杂的生命周期中会经历一系列分化过程。虽然克氏锥虫基因组中并非所有自噬基因都已被鉴定出来,但先前的研究已经证明存在必需的自噬相关蛋白。在饥饿条件下,寄生虫中Atg8/LC3在其他生物体中的同源物TcAtg8位于自噬体样小泡中。在这项工作中,我们对克氏锥虫从无鞭毛体向感染性锥鞭毛体形式分化的自噬途径进行了表征,这一过程称为循环体发育。我们证明在循环体发育过程中自噬受到刺激,并且自噬的诱导促进了这一过程。此外,除了巴弗洛霉素外,其他经典的自噬调节剂对克氏锥虫自噬有类似的影响。我们还表明亚精胺和相关多胺可以正向调节寄生虫自噬和分化。我们得出结论,多胺代谢和自噬都是克氏锥虫循环体发育过程中的关键过程,可作为药物靶点来阻止寄生虫生命周期的进展。