Thanasuwan Sirikanda, Piratae Supawadee, Brindley Paul J, Loukas Alex, Kaewkes Sasithorn, Laha Thewarach
Department of Parasitology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
Parasit Vectors. 2014 May 14;7:224. doi: 10.1186/1756-3305-7-224.
Opisthorchiasis and Opisthorchis viverrini-associated bile duct cancer represent major public health threats in Thailand and Laos. The tegument of this food borne fluke plays pivotal roles in parasite metabolism, homeostasis and osmoregulation. Excretory/secretory products also pass from the fluke to the biliary environment, products that likely underlie pathogenesis of liver fluke infection. Aquaporins (AQPs), belong to the major intrinsic protein superfamily of integral plasma membrane channel proteins that selectively transport water across cell membranes. AQPs play key roles as water and ion transport channels through the tegument of helminth parasites.
Here, two forms of AQP mRNAs from the adult developmental stage of O. viverrini, termed O. viverrini aquaporin-1 and -2 (Ov-aqp-1 and -2) were investigated. Roles of Ov-aqp-1 and -2 in the movement of water across the tegument of this carcinogenic liver fluke were investigated using RNA interference.
Ov-AQP-1 and Ov-AQP-2 contain unique characteristic asparagine-proline-alanine (NPA) motifs of AQP transmembrane proteins. Phylogenetic analysis indicated that Ov-AQPs belong to an expanding group of aquaglyceroporin-like water channel proteins characterized from helminth and protozoan parasites, which is pivotal to the specialized requirements of water and solute control during parasitism. Elevated transcription of Ov-aqp-1 was evident in the egg, cercaria, metacercaria and adult stages of O. viverrini, whereas Ov-aqp-2 transcripts were detected at higher level in egg, metacercaria, cercaria and adult stage, respectively. RNA interference using electroporated dsRNA suppressed transcript levels of Ov-aqp-1 and Ov-aqp-2 in adult worms by 58-99% over periods of up to 16 days in vitro. Suppression of Ov-aqp-1 and Ov-aqp-2 in vitro disabled water transport in adult flukes.
The apparently pivotal roles of Ov-AQP in solute homeostasis at the fluke surface suggest that deeper investigation will be informative for the pathophysiology of O. viverrini, and may uncover intervention targets, particularly in view of the singularly notable predilection of this pathogen for residence within ducts of the biliary tree.
华支睾吸虫病及与华支睾吸虫相关的胆管癌是泰国和老挝主要的公共卫生威胁。这种食源性吸虫的体表在寄生虫代谢、体内平衡及渗透调节中发挥着关键作用。排泄/分泌产物也从吸虫进入胆管环境,这些产物可能是肝吸虫感染发病机制的基础。水通道蛋白(AQP)属于主要内在蛋白超家族,是整合质膜通道蛋白,可选择性地跨细胞膜转运水。AQP作为水和离子转运通道,在蠕虫寄生虫体表发挥关键作用。
在此,研究了来自成年华支睾吸虫发育阶段的两种形式的AQP mRNA,分别称为华支睾吸虫水通道蛋白-1和-2(Ov-aqp-1和-2)。使用RNA干扰研究了Ov-aqp-1和-2在这种致癌肝吸虫体表水转运中的作用。
Ov-AQP-1和Ov-AQP-2含有AQP跨膜蛋白独特的天冬酰胺-脯氨酸-丙氨酸(NPA)基序。系统发育分析表明,Ov-AQP属于一个不断扩大的水甘油通道蛋白样水通道蛋白组,该组蛋白在蠕虫和原生动物寄生虫中具有特征性,对于寄生过程中对水和溶质控制的特殊需求至关重要。在华支睾吸虫的卵、尾蚴、囊蚴和成虫阶段,Ov-aqp-1的转录水平均明显升高,而Ov-aqp-2转录本在卵、囊蚴、尾蚴和成虫阶段分别在较高水平被检测到。使用电穿孔双链RNA进行RNA干扰,在体外长达16天的时间内,可使成虫中Ov-aqp-1和Ov-aqp-2的转录水平降低58%-99%。体外抑制Ov-aqp-1和Ov-aqp-2会使成虫吸虫的水转运功能丧失。
Ov-AQP在吸虫表面溶质稳态中显然起着关键作用,这表明深入研究对华支睾吸虫的病理生理学具有指导意义,并且可能揭示干预靶点,特别是鉴于这种病原体特别倾向于寄生于胆管树内。