Verma Jitender Kumar, Rastogi Ruchir, Mukhopadhyay Amitabha
National Institute of Immunology, New Delhi, India.
PLoS Pathog. 2017 Jun 26;13(6):e1006459. doi: 10.1371/journal.ppat.1006459. eCollection 2017 Jun.
Several intracellular pathogens arrest the phagosome maturation in the host cells to avoid transport to lysosomes. In contrast, the Leishmania containing parasitophorous vacuole (PV) is shown to recruit lysosomal markers and thus Leishmania is postulated to be residing in the phagolysosomes in macrophages. Here, we report that Leishmania donovani specifically upregulates the expression of Rab5a by degrading c-Jun via their metalloprotease gp63 to downregulate the expression of miR-494 in THP-1 differentiated human macrophages. Our results also show that miR-494 negatively regulates the expression of Rab5a in cells. Subsequently, L. donovani recruits and retains Rab5a and EEA1 on PV to reside in early endosomes and inhibits transport to lysosomes in human macrophages. Similarly, we have also observed that Leishmania PV also recruits Rab5a by upregulating its expression in human PBMC differentiated macrophages. However, the parasite modulates the endosome by recruiting Lamp1 and inactive pro-CathepsinD on PV via the overexpression of Rab5a in infected cells. Furthermore, siRNA knockdown of Rab5a or overexpression of miR-494 in human macrophages significantly inhibits the survival of the parasites. These results provide the first mechanistic insights of parasite-mediated remodeling of endo-lysosomal trafficking to reside in a specialized early endocytic compartment.
几种细胞内病原体阻止宿主细胞中的吞噬体成熟,以避免被转运至溶酶体。相比之下,含利什曼原虫的寄生泡(PV)显示会募集溶酶体标记物,因此推测利什曼原虫存在于巨噬细胞的吞噬溶酶体中。在此,我们报告杜氏利什曼原虫通过其金属蛋白酶gp63降解c-Jun,从而特异性上调Rab5a的表达,以下调THP-1分化的人巨噬细胞中miR-494的表达。我们的结果还表明,miR-494在细胞中负向调节Rab5a的表达。随后,杜氏利什曼原虫在PV上募集并保留Rab5a和EEA1,以驻留在早期内体中,并抑制在人巨噬细胞中向溶酶体的转运。同样,我们还观察到利什曼原虫PV在人PBMC分化的巨噬细胞中通过上调Rab5a的表达来募集Rab5a。然而,寄生虫通过在感染细胞中过表达Rab5a,在PV上募集Lamp1和无活性的组织蛋白酶D前体来调节内体。此外,在人巨噬细胞中敲低Rab5a的siRNA或过表达miR-494可显著抑制寄生虫的存活。这些结果首次提供了寄生虫介导的内吞-溶酶体运输重塑以驻留在特殊早期内吞区室的机制性见解。
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