Phagocytosis in Entamoeba histolytica

Somlata,; Bhattacharya, Alok

doi:10.1007/978-4-431-55200-0_12

Cited by 2 publications

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“…These genes included amoebapore A, B and C precursors, Gal/GalNAc lectin light subunit and a few of the cysteine proteases (CPs) (isoform EhCP-A5, considered as a virulence determinant [ 5 ]) (see Additional file 6 ). Calcium binding proteins are also important for amoebic virulence, being required for efficient phagocytosis [ 19 , 20 ]. Some of the calcium binding protein genes were also amongst the VH class.…”

Section: Resultsmentioning

confidence: 99%

Transcriptomic analysis reveals novel downstream regulatory motifs and highly transcribed virulence factor genes of Entamoeba histolytica

et al. 2019

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BackgroundPromoter motifs in Entamoeba histolytica were earlier analysed using microarray data with lower dynamic range of gene expression. Additionally, previous transcriptomic studies did not provide information on the nature of highly transcribed genes, and downstream promoter motifs important for gene expression. To address these issues we generated RNA-Seq data and identified the high and low expressing genes, especially with respect to virulence potential. We analysed sequences both upstream and downstream of start site for important motifs.ResultsWe used RNA-Seq data to classify genes according to expression levels, which ranged six orders of magnitude. Data were validated by reporter gene expression. Virulence-related genes (except AIG1) were amongst the highly expressed, while some kinases and BspA family genes were poorly expressed. We looked for conserved motifs in sequences upstream and downstream of the initiation codon. Following enrichment by AME we found seven motifs significantly enriched in high expression- and three in low expression-classes. Two of these motifs (M4 and M6) were located downstream of AUG, were exclusively enriched in high expression class, and were mostly found in ribosomal protein, and translation-related genes. Motif deletion resulted in drastic down regulation of reporter gene expression, showing functional relevance. Distribution of core promoter motifs (TATA, GAAC, and Inr) in all genes revealed that genes with downstream motifs were not preferentially associated with TATA-less promoters. We looked at gene expression changes in cells subjected to growth stress by serum starvation, and experimentally validated the data. Genes showing maximum up regulation belonged to the low or medium expression class, and included genes in signalling pathways, lipid metabolism, DNA repair, Myb transcription factors, BspA, and heat shock. Genes showing maximum down regulation belonged to the high or medium expression class. They included genes for signalling factors, actin, Ariel family, and ribosome biogenesis factors.ConclusionOur analysis has added important new information about the E. histolytica transcriptome. We report for the first time two downstream motifs required for gene expression, which could be used for over expression of E. histolytica genes. Most of the virulence-related genes in this parasite are highly expressed in culture.Electronic supplementary materialThe online version of this article (10.1186/s12864-019-5570-z) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Transcriptomic analysis reveals novel downstream regulatory motifs and highly transcribed virulence factor genes of Entamoeba histolytica

et al. 2019

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PI Kinase-EhGEF2-EhRho5 axis contributes to LPA stimulated macropinocytosis in Entamoeba histolytica

et al. 2022

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Entamoeba histolytica is a protozoan responsible for several pathologies in humans. Trophozoites breach the intestinal site to enter the bloodstream and thus traverse to a secondary site. Macropinocytosis and phagocytosis, collectively accounting for heterophagy, are the two major processes responsible for sustenance of Entamoeba histolytica within the host. Both of these processes require significant rearrangements in the structure to entrap the target. Rho GTPases play an indispensable role in mustering proteins that regulate cytoskeletal remodelling. Unlike phagocytosis which has been studied in extensive detail, information on machinery of macropinocytosis in E. histolytica is still limited. In the current study, using site directed mutagenesis and RNAi based silencing, coupled with functional studies, we have demonstrated the involvement of EhRho5 in constitutive and LPA stimulated macropinocytosis. We also report that LPA, a bioactive phospholipid present in the bloodstream of the host, activates EhRho5 and translocates it from cytosol to plasma membrane and endomembrane compartments. Using biochemical and FRAP studies, we established that a PI Kinase acts upstream of EhRho5 in LPA mediated signalling. We further identified EhGEF2 as a guanine nucleotide exchange factor of EhRho5. In the amoebic trophozoites, EhGEF2 depletion leads to reduced macropinocytic efficiency of trophozoites, thus phenocopying its substrate. Upon LPA stimulation, EhGEF2 is found to sequester near the plasma membrane in a wortmannin sensitive fashion, explaining a possible mode for activation of EhRho5 in the amoebic trophozoites. Collectively, we propose that LPA stimulated macropinocytosis in E. histolytica is driven by the PI Kinase-EhGEF2-EhRho5 axis.

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Phagocytosis in Entamoeba histolytica

Cited by 2 publications

References 81 publications

Transcriptomic analysis reveals novel downstream regulatory motifs and highly transcribed virulence factor genes of Entamoeba histolytica

Transcriptomic analysis reveals novel downstream regulatory motifs and highly transcribed virulence factor genes of Entamoeba histolytica

PI Kinase-EhGEF2-EhRho5 axis contributes to LPA stimulated macropinocytosis in Entamoeba histolytica

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