Silencing of the Laminin γ-1 Gene Blocks Trypanosoma cruzi Infection

Abstract

It is thought that Trypanosoma cruzi, the protozoan that causes Chagas' disease, modulates the extracellular matrix network to facilitate infection of human cells. However, direct evidence to document this phenomenon is lacking. Here we show that the T. cruzi gp83 ligand, a cell surface trans-sialidase-like molecule that the parasite uses to attach to host cells, increases the level of laminin ␥-1 transcript and its expression in mammalian cells, leading to an increase in cellular infection. Stable RNA interference (RNAi) with host cell laminin ␥-1 knocks down the levels of laminin ␥-1 transcript and protein expression in mammalian cells, causing a dramatic reduction in cellular infection by T. cruzi. Thus, host laminin ␥-1, which is regulated by the parasite, plays a crucial role in the early process of infection. This is the first report showing that knocking down the expression of a human gene by RNAi inhibits the infection of an intracellular parasite.

Mechanism of Congenital Chagas Disease: Effective Infection Depends on the Interplay Between Trypanosoma cruzi and the Different Tissue Compartments in the Chorionic Villi of the Human Placenta

“…T. cruzi presents surface molecules, such as gp85 (Marino et al, 2003) and gp83 (Nde et al, 2006) glycoproteins that bind to laminin and fibronectin (Marino et al, 2003;Nde et al, 2006) and to sulfated glycosamineglicans such as heparan sulphate (Lima et al, 2002). We have previously shown that the parasite induces a decrease of glycosylated molecules of the basal lamina, specifically laminin and heparan sulphate (Duaso et al, 2010;Duaso et al 2011b).…”

“…The increase of laminin expression could be induced by the parasite, which needs to attach to ECM molecules for cellular invasion (Marino et al, 2003). The silencing of the laminin gene inhibits cell invasion of the T. cruzi (Nde et al, 2006). The parasitic protease cruzipain degrades collagen IV and fibronectin, exposing epitopes to which T. cruzi binds (Scharfstein and Morrot, 1999), facilitating also the binding to laminin and consequently the cell invasion.…”

Molecular analysis of early host cell infection by Trypanosoma cruzi

“…Since this trypanosome ligand is released from the parasite by the action of a parasite PLC in order to signal macrophages and non-phagocytic cells, special attention has been given to its description and characterization. Previous reports have shown that the T. cruzi surface gp83 (45,(50)(51)(52) is expressed only in invasive trypomastigotes (48), is more expressed in highly than weakly infective trypomastigote clones (46) and that blocking this molecule with antigp83 antibodies reduces trypanosome binding and invasion (48). Purified soluble gp83, from PLC-treated T. cruzi trypomastigote membranes, binds to myoblasts, fibroblasts and macrophages to mediate trypanosome entry (62).…”

“…The candidate trypomastigote ligands for structural and atomic analysis are TS, TS-like molecules (36,53,57), mucins (58), heparin binding protein (59), and surface casein kinase II substrates (60) that bind to nonphagocytic cells, kinases and to extracellular matrix proteins (52)(53)(54)(55)(56)(57)(58)(59)(60)(61) and to host cell receptors on non-phagocytic cells in order to invade them (52)(53)(54)(55)(56)(57). It is thought that trypanosome trans-sialidases transfer sialic acids to trypanosome mucins and serve as acceptors of sialic acids during infection.…”

“…TS activity is unique in that it does not use CMP-sialic acid as the monosaccharide donor, it is located on the parasite surface instead of at the Golgi apparatus, and it is more efficient in transferring rather than hydrolyzing terminal sialic acids between glycoconjugates. In addition to its role in sialic-acid salvage, TS and TS-like molecules (anchored to the parasite membrane or shed into the bloodstream) can bind to mammalian cell receptors to mediate trypanosome binding and entry (44)(45)(46)(47)(48)(49)(50)(51)(52) as well as to undermine host defense mechanisms (53)(54).…”