Regulation of expression of ribosomal protein L‐21 genes of <i>Entamoeba histolytica</i> and <i>E. dispar</i> is at the post‐transcriptional level

Moshitch-Moshkovitch, S; Petter, R; Levitan, Alexander; Stolarsky, Tamara; Mirelman, David

doi:10.1046/j.1365-2958.1998.00686.x

Cited by 17 publications

(11 citation statements)

References 17 publications

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“…5A). pTS4‐transfected trophozoites (Moshitch‐Moshkovitch et al ., 1997), which contain the CAT reporter gene under the g34 gene promoter, were used here as a control, and they exhibited a cytopathic activity very similar to that of non‐transfected trophozoites of the parent E. histolytica strain. Transfectant pSA20 could not be used as a control because it is inhibited in its virulence (Ankri et al ., 1999a).…”

Section: Resultsmentioning

confidence: 99%

“…Our relative success in inhibiting the synthesis of certain amoeba components by antisense RNA is mainly a result of the use of the 5′ and 3′ regulatory elements of the g34 gene copy of the ribosomal protein RP‐L21 in the transfection plasmids. The transcripts containing the g34 gene regulatory elements are incapable of binding to the polyribosomal fraction of E. histolytica (Petter et al ., 1994; Moshitch‐Moshkovitch et al ., 1997). The antisense transcripts accumulate and form hybrids with the endogenous (sense) transcript, which then become targets for specific nucleases that degrade the dsRNA region (Nellen and Lichtenstein, 1993).…”

Section: Discussionmentioning

confidence: 99%

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Antisense inhibition of amoebapore expression inEntamoeba histolyticacauses a decrease in amoebic virulence

Bracha

Nuchamowitz

Leippe

et al. 1999

Molecular Microbiology

101

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SummaryAmoebapores have been proposed to be a major pathogenicity factor of the protozoan parasite Entamoeba histolytica, which is responsible for the killing of target cells. These 77-residue peptides are structural and functional analogues of NK-lysin and granulysin of porcine and human cytotoxic lymphocytes. Inhibition of amoebapore gene expression in amoebae was obtained following transfection with a hybrid plasmid construct (pAP-R2) containing the Neo resistance gene and the gene coding for amoebapore A, including its 58 and 38 untranslated region (UTR) sequences, in reverse orientation under a promoter (g34) taken from one of the E. histolytica ribosomal protein (RP-L21) gene copies. Transfectants of virulent E. histolytica strain HM-1:IMSS, in which the expression of amoebapore was inhibited by , 60%, were signi®cantly less pathogenic. Cytopathic and cytolytic activities of viable trophozoites against mammalian nucleated cells, as well as lysis of red blood cells, were markedly inhibited. Moreover, trophozoite extracts of pAP-R2 transfectant displayed lower pore-forming activity and were less potent in inhibiting bacterial growth compared with controls. Notably, liver abscess formation in hamsters by the pAP-R2 transfectant was substantially impaired. These results demonstrate for the ®rst time that amoebapore is one of the pathogenicity factors by which trophozoites of E. histolytica exert their remarkable cytolytic and tissue destructive activity.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Antisense inhibition of amoebapore expression inEntamoeba histolyticacauses a decrease in amoebic virulence

Bracha

Nuchamowitz

Leippe

et al. 1999

Molecular Microbiology

101

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“…This success was attributed to the use of one of the ribosomal protein L21 promoters. The accumulation in the trophozoites of free antisense ehcp 5 mRNA, transcribed with an rp‐L21 promoter (Moshitch‐Moshkovitch et al ., 1998), appears to be the reason for the present successful inhibition of CP expression.…”

Section: Discussionmentioning

confidence: 99%

Antisense inhibition of expression of cysteine proteinases does not affect Entamoeba histolytica cytopathic or haemolytic activity but inhibits phagocytosis

Ankri

Stolarsky

Mirelman

1998

Molecular Microbiology

135

118

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SummaryInhibition of most of the expression of the cysteine proteinases of Entamoeba histolytica strain HM-1: IMSS was successfully performed by transcription of ehcp5 antisense RNA using the promoter of ehg34, which encodes a L21 ribosomal protein of E. histolytica. We have generated a stable transfectant in which the overall level of cysteine proteinase activity is strongly reduced (Ϸ 90%). This transfectant has a normal growth rate in Diamond's TYI-S-33 medium, a cytopathic and haemolytic activity similar to the control HM-1:IMSS pEhAct-Neo transfectant but with a significantly lower phagocytic activity.

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“…For antisense RNA inhibition, a series of plasmid vectors both inducible and constitutive has been successfully used to study the in vivo effects of certain genes in Entamoeba spp. (2,3,6,19,21,24,32). In this study a cloned fragment of the E. histolytica eh29 gene was inserted in the antisense orientation in a tetracycline-inducible expression vector (18,27,29).…”

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confidence: 99%

The 29-Kilodalton Thiol-Dependent Peroxidase of Entamoeba histolytica Is a Factor Involved in Pathogenesis and Survival of the Parasite during Oxidative Stress

et al. 2007

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The 29-kDa surface antigen (thiol-dependent peroxidase; Eh29) of Entamoeba histolytica exhibits peroxidative and protective antioxidant activities. During tissue invasion, the trophozoites are exposed to oxidative stress and need to deal with highly toxic reactive oxygen species (ROS). In this investigation, attempts have been made to understand the role of the 29-kDa peroxidase gene in parasite survival and pathogenesis. Inhibition of eh29 gene expression by antisense RNA technology has shown approximately 55% inhibition in eh29 expression, maximum ROS accumulation, and significantly lower viability in 29-kDa downregulated trophozoites during oxidative stress. The cytopathic and cytotoxic activities were also found to decrease effectively in the 29-kDa downregulated trophozoites. Size of liver abscesses was substantially lower in hamsters inoculated with 29-kDa downregulated trophozoites compared to the normal HM1:IMSS. These findings clearly suggest that the 29-kDa protein of E. histolytica has a role in both survival of trophozoites in the presence of ROS and pathogenesis of amoebiasis.Entamoeba histolytica, the enteric protozoa, is a well-established causative agent of amoebic dysentery and liver abscesses in humans (37). E. histolytica is well known for its high potential for invading and destroying human tissue, leading to diseases such as hemorrhagic colitis and extraintestinal abscesses (30). The parasite usually lives and multiplies within the human gut, which constitutes an environment of reduced oxygen pressure. During tissue invasion, E. histolytica is exposed to elevated amounts of exogenous reactive oxygen species (ROS), such as superoxide radical anions (O 2 ⅐ Ϫ ) and hydrogen peroxide (H 2 O 2 ) (14, 26). These highly toxic molecules cause severe damage to biological macromolecules, leading to metabolic malfunctions. In addition, E. histolytica has to inactivate the ROS produced by endogenous enzymes for its survival. Several defense mechanisms exist in which a wide array of enzymatic and nonenzymatic antioxidants, including superoxide dismutase (SOD), glutathione peroxidase, catalase, and glutathione, play an active role in cell survival during oxidative stress. E. histolytica produces an iron-containing SOD that is induced by superoxide anions to produce H 2 O 2 (9). Hydroperoxides produced during oxidative stress could be detoxified by a bifunctional NADPH:flavin oxidoreductase containing NADPH-dependent disulfide reductase and a H 2 O 2 -forming NADPH oxidase activity (10, 12). Catalase and glutathione reductase systems are absent in E. histolytica, but it encodes a 29-kDa cysteine-rich antigen (thiol-dependent peroxiredoxin) located on the surface of the trophozoites (8). The 29-kDa thiol-dependent peroxiredoxin of E. histolytica (Eh29) is homologous to AhpC (alkyl hydroperoxide C-22 protein) of Salmonella enterica serovar Typhimurium and Saccharomyces cerevisiae thiol-specific antioxidant protein (17). In our previous study it was clearly demonstrated that the enzymes SOD and Eh29 increased...

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Regulation of expression of ribosomal protein L‐21 genes of Entamoeba histolytica and E. dispar is at the post‐transcriptional level

Cited by 17 publications

References 17 publications

Antisense inhibition of amoebapore expression inEntamoeba histolyticacauses a decrease in amoebic virulence

Antisense inhibition of amoebapore expression inEntamoeba histolyticacauses a decrease in amoebic virulence

Antisense inhibition of expression of cysteine proteinases does not affect Entamoeba histolytica cytopathic or haemolytic activity but inhibits phagocytosis

The 29-Kilodalton Thiol-Dependent Peroxidase of Entamoeba histolytica Is a Factor Involved in Pathogenesis and Survival of the Parasite during Oxidative Stress

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