Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Friuli 2434, 5000, Córdoba, Argentina.
Parasitol Res. 2013 Apr;112(4):1813-8. doi: 10.1007/s00436-012-3253-7. Epub 2013 Jan 12.
The early branching Giardia lamblia has highly polarized vacuoles, located underneath the plasma membrane, which have at least some of the characteristics of endosomes and of lysosomes. These peripheral vacuoles (PVs) are necessary for nutrient uptake and the maintenance of plasma membrane composition, but whether they carry out sorting and segregation of receptors and ligands is a matter of debate. Here, we showed that the internalization of low-density lipoprotein (LDL) to the PVs is highly dynamic in trophozoites with a rate similar to the internalization of the low-density lipoprotein receptor-related protein 1. Moreover, by analyzing receptor-mediated and fluid-phase endocytosis in living cells, we showed that after endocytosis LDL but not dextran moved laterally between the PVs. We speculate on PV functional heterogeneity and maturation in this parasite.
早期分支的蓝氏贾第鞭毛虫具有高度极化的液泡，位于质膜下方，这些液泡至少具有一些内体和溶酶体的特征。这些外周液泡（PVs）对于营养物质的摄取和维持质膜组成是必要的，但它们是否进行受体和配体的分拣和隔离是一个有争议的问题。在这里，我们表明，在营养体中，低密度脂蛋白（LDL）内化到 PVs 是高度动态的，其内化速率与低密度脂蛋白受体相关蛋白 1 的内化速率相似。此外，通过分析活细胞中受体介导的和流体相胞吞作用，我们表明，内吞作用后 LDL 而不是葡聚糖在 PVs 之间侧向移动。我们推测该寄生虫的 PV 功能异质性和成熟度。
