Structural Features Affecting Trafficking, Processing, and Secretion of Trypanosoma cruzi Mucins

Canepa, Gaspar E.; Mesías, Andrea C.; Yu, Hai; Chen, Xi; Buscaglia, Carlos A.

doi:10.1074/jbc.m112.354696

Cited by 25 publications

(39 citation statements)

References 58 publications

(79 reference statements)

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“…1C). These values are comparable to those from other studies using pTEX or pTEX-derived vectors to overexpress proteins in the cytosol (78,79), mitochondria (80), glycosomes (81), endosomal/lysosomal system and reservosomes (75,82), ER (68), flagellar pocket (83), or plasma membrane (69,(84)(85)(86) of T. cruzi. The protein was stable, with no indication of a C-terminal proteolytic cleavage event observed when expressed in L. tarentolae (21), and it appeared to be inserted into the rER and N-glycosylated normally (Fig.…”

Section: Discussionsupporting

confidence: 84%

“…Similar findings were observed for overexpressed TcOGNT2myc, though most of the cells (ϳ70%; n ϭ 200) exhibited multiple sites of accumulation (Fig. 3C) that were dissimilar to the rough endoplasmic reticulum (rER), whose resident proteins, such as BiP and calreticulin, exhibit a punctate pattern throughout the cell body and around the nucleus (68,69). Simultaneous localization of cruzipain, a marker for the reservosome, shows that these compartments also appear independent of this organelle.…”

Section: Overexpression Of Tcognt2 In Epimastigotessupporting

confidence: 75%

“…Although it is difficult to exclude the possibility that the 7-fold overexpression of a single protein, such as TcOGNT2, inhibits metacyclogenesis by a nonspecific stress effect, it is notable that proliferation and TCT production were not affected ( Fig. 8 and 9) and that overexpression of other proteins failed to inhibit this process (58,68,69,(78)(79)(80)(81)(82)(84)(85)(86). The protein burden of 7-fold accumulation of a single enzyme is not anticipated to be great, and indeed, overexpression of a truncated N-terminal fragment of the TcOGNT2 homolog TbOGNT2 in Trypanosoma brucei did not affect Golgi replication (93).…”

Section: Discussionmentioning

confidence: 99%

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Golgi UDP-GlcNAc:Polypeptide O -α- N -Acetyl- d -Glucosaminyltransferase 2 (TcOGNT2) Regulates Trypomastigote Production and Function in Trypanosoma cruzi

et al. 2014

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e All life cycle stages of the protozoan parasite Trypanosoma cruzi are enveloped by mucin-like glycoproteins which, despite major changes in their polypeptide cores, are extensively and similarly O-glycosylated. O-Glycan biosynthesis is initiated by the addition of ␣GlcNAc to Thr in a reaction catalyzed by Golgi UDP-GlcNAc:polypeptide O-␣-N-acetyl-D-glucosaminyltransferases (pp␣GlcNAcTs), which are encoded by TcOGNT1 and TcOGNT2. We now directly show that TcOGNT2 is associated with the Golgi apparatus of the epimastigote stage and is markedly downregulated in both differentiated metacyclic trypomastigotes (MCTs) and cell culture-derived trypomastigotes (TCTs). The significance of downregulation was examined by forced continued expression of TcOGNT2, which resulted in a substantial increase of TcOGNT2 protein levels but only modestly increased pp␣GlcNAcT activity in extracts and altered cell surface glycosylation in TCTs. Constitutive TcOGNT2 overexpression had no discernible effect on proliferating epimastigotes but negatively affected production of both types of trypomastigotes. MCTs differentiated from epimastigotes at a low frequency, though they were apparently normal based on morphological and biochemical criteria. However, these MCTs exhibited an impaired ability to produce amastigotes and TCTs in cell culture monolayers, most likely due to a reduced infection frequency. Remarkably, inhibition of MCT production did not depend on TcOGNT2 catalytic activity, whereas TCT production was inhibited only by active TcOGNT2. These findings indicate that TcOGNT2 downregulation is important for proper differentiation of MCTs and functioning of TCTs and that TcOGNT2 regulates these functions by using both catalytic and noncatalytic mechanisms.

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Section: Discussionsupporting

confidence: 84%

Section: Overexpression Of Tcognt2 In Epimastigotessupporting

confidence: 75%

Section: Discussionmentioning

confidence: 99%

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Golgi UDP-GlcNAc:Polypeptide O -α- N -Acetyl- d -Glucosaminyltransferase 2 (TcOGNT2) Regulates Trypomastigote Production and Function in Trypanosoma cruzi

et al. 2014

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“…Similarly to other protozoa of medical and veterinary relevance, the T. cruzi surface coat is majorly composed of glycophosphatidylinositol (GPI) (see Glossary) -anchored glycoconjugates of varied natures, often of types absent in insects or mammals [5]. The advantages of GPI moieties over trans -membrane domains are not clear, though they may provide surface molecules of trypanosomatids with accurate sorting signals in the secretory and/or endocytic pathways [6–8]. Alternatively, or additionally, it has been proposed that GPI-anchored molecules may pack at higher densities on the surface of trypanosomatids for protective and/or specialized signal transduction purposes and, due to their ‘labile’ membrane anchorage, they may be conditionally secreted as a means to get rid of immune complexes and/or to exchange signals among cells [5].…”

Section: Trypanosoma Cruzi: Dressed For Successmentioning

confidence: 99%

The Trypanosoma cruzi Surface, a Nanoscale Patchwork Quilt

Mucci

Lantos

Buscaglia

et al. 2017

Trends in Parasitology

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The Trypanosoma cruzi trypomastigote membrane provides a major protective role against mammalian host-derived defense mechanisms while allowing the parasite to interact with different cell types and trigger pathogenesis. This surface has been historically appreciated as a rather unstructured ‘coat’, mainly consisting of a continuous layer of glycolipids and heavily O-glycosylated mucins, occasionally intercalated with different developmentally-regulated molecules displaying adhesive and/or enzymatic properties. Recent findings, however, indicate that the trypomastigote membrane is made up of multiple, densely packed and discrete 10–150 nm lipid-driven domains bearing different protein composition; hence resembling a highly organized ‘patchwork quilt’ design. Here, we discuss different aspects underlying the biogenesis, assembly and dynamics of this cutting edge fashion outfit, as well as its functional implications.

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“…GPI-minus variants accumulate in the ER indicating that GPI anchor acts as a forward transport signal for progressing along the secretory pathway as suggested for T. cruzi mucins [73]. Heterologous expression of GP82 into mammalian cells indicated that the requirements for GPI-anchoring are different between T. cruzi and mammalian cells.…”

Section: Concluding Remarks and Perspectivesmentioning

confidence: 99%

Genetic Structure and Expression of the Surface Glycoprotein GP82, the Main Adhesin of Trypanosoma cruzi Metacyclic Trypomastigotes

Corrêa

Cordero

Gentil

et al. 2013

The Scientific World Journal

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T. cruzi improves the likelihood of invading or adapting to the host through its capacity to present a large repertoire of surface molecules. The metacyclic stage-specific surface glycoprotein GP82 has been implicated in host cell invasion. GP82 is encoded by multiple genes from the trans-sialidase superfamily. GP82 shows a modular organization, with some variation of N-terminal region flanking a conserved central core where the binding sites to the mammalian cell and gastric mucin are located. The function of GP82 as adhesin in host cell invasion process could expose the protein to an intense conservative and selective pressure. GP82 is a GPI-anchored surface protein, synthesized as a 70 kDa precursor devoid of N-linked sugars. GPI-minus variants accumulate in the ER indicating that GPI anchor acts as a forward transport signal for progressing along the secretory pathway as suggested for T. cruzi mucins. It has been demonstrated that the expression of GP82 is constitutive and may be regulated at post-transcriptional level, for instance, at translational level and/or mRNA stabilization. GP82 mRNAs are mobilized to polysomes and consequently translated, but only in metacyclic trypomastigotes. Analysis of transgenic parasites indicates that the mechanism regulating GP82 expression involves multiple elements in the 3′UTR.

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Structural Features Affecting Trafficking, Processing, and Secretion of Trypanosoma cruzi Mucins

Cited by 25 publications

References 58 publications

Golgi UDP-GlcNAc:Polypeptide O -α- N -Acetyl- d -Glucosaminyltransferase 2 (TcOGNT2) Regulates Trypomastigote Production and Function in Trypanosoma cruzi

Golgi UDP-GlcNAc:Polypeptide O -α- N -Acetyl- d -Glucosaminyltransferase 2 (TcOGNT2) Regulates Trypomastigote Production and Function in Trypanosoma cruzi

The Trypanosoma cruzi Surface, a Nanoscale Patchwork Quilt

Genetic Structure and Expression of the Surface Glycoprotein GP82, the Main Adhesin of Trypanosoma cruzi Metacyclic Trypomastigotes

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