Inhibition of encystation of Entamoeba invadens by wortmannin

Makioka, Asao; Kumagai, Masahiro; Ohtomo, Hiroshi; Kobayashi, Seiki; Takeuchi, Tsutomu

doi:10.1007/s004360000339

Cited by 19 publications

(15 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…7A). These data are consistent with previous findings (31). The immunofluorescence assay showed that the formation of Atg8-associated structures was abolished by wortmannin ( Fig.…”

Section: Conservation Of the Atg8 Conjugation Pathway In Relatedsupporting

confidence: 93%

Autophagy during Proliferation and Encystation in the Protozoan Parasite Entamoeba invadens

2008

View full text Add to dashboard Cite

Autophagy is one of the three systems responsible for the degradation of cytosolic proteins and organelles. Autophagy has been implicated in the stress response to starvation, antigen cross-presentation, the defense against invading bacteria and viruses, differentiation, and development. Saccharomyces cerevisiae Atg8 and its mammalian ortholog, LC3, play an essential role in autophagy. The intestinal protozoan parasite Entamoeba histolytica and a related reptilian species, Entamoeba invadens, possess the Atg8 conjugation system, consisting of Atg8, Atg4, Atg3, and Atg7, but lack the Atg5-to-Atg12 conjugation system. Immunofluorescence imaging revealed that polymorphic Atg8-associated structures emerged in the logarithmic growth phase and decreased in the stationary phase and also increased in the early phase of encystation in E. invadens. Immunoblot analysis showed that the increase in phosphatidylethanolamine-conjugated membrane-associated Atg8 was also accompanied by the emergence of Atg8-associated structures during the proliferation and differentiation mentioned above. Specific inhibitors of class I and III phosphatidylinositol 3-kinases simultaneously inhibited both the growth of trophozoites and autophagy and also both encystation and autophagy in E. invadens. These results suggest that the core machinery for autophagy is conserved and plays an important role during proliferation and differentiation in Entamoeba.

show abstract

“…7A). These data are consistent with previous findings (31). The immunofluorescence assay showed that the formation of Atg8-associated structures was abolished by wortmannin ( Fig.…”

Section: Conservation Of the Atg8 Conjugation Pathway In Relatedsupporting

confidence: 93%

Autophagy during Proliferation and Encystation in the Protozoan Parasite Entamoeba invadens

2008

View full text Add to dashboard Cite

show abstract

“…CaM is associated with the secretion of electron-dense granules containing collagenase, as well as the growth and encystation of Entamoeba spp. [47, 48]. Makioka et al [49] demonstrated the function of CaM in the excystation and metacystic development of E. invadens as a model for E. histolytica.…”

Section: Resultsmentioning

confidence: 99%

Proteome analysis of excretory-secretory proteins of Entamoeba histolytica HM1:IMSS via LC–ESI–MS/MS and LC–MALDI–TOF/TOF

et al. 2016

View full text Add to dashboard Cite

BackgroundExcretory-secretory (ES) proteins of E. histolytica are thought to play important roles in the host invasion, metabolism, and defence. Elucidation of the types and functions of E. histolytica ES proteins can further our understanding of the disease pathogenesis. Thus, the aim of this study is to use proteomics approach to better understand the complex ES proteins of the protozoa.Methods E. histolytica ES proteins were prepared by culturing the trophozoites in protein-free medium. The ES proteins were identified using two mass spectrometry tools, namely, LC–ESI–MS/MS and LC–MALDI–TOF/TOF. The identified proteins were then classified according to their biological processes, molecular functions, and cellular components using the Panther classification system (PantherDB).ResultsA complementary list of 219 proteins was identified; this comprised 201 proteins detected by LC–ESI–MS/MS and 107 proteins by LC–MALDI–TOF/TOF. Of the 219 proteins, 89 were identified by both mass-spectrometry systems, while 112 and 18 proteins were detected exclusively by LC–ESI–MS/MS and LC–MALDI–TOF/TOF respectively. Biological protein functional analysis using PantherDB showed that 27% of the proteins were involved in metabolic processes. Using molecular functional and cellular component analyses, 35% of the proteins were found to be involved in catalytic activity, and 21% were associated with the cell parts.ConclusionThis study showed that complementary use of LC–ESI–MS/MS and LC–MALDI–TOF/TOF has improved the identification of ES proteins. The results have increased our understanding of the types of proteins excreted/secreted by the amoeba and provided further evidence of the involvement of ES proteins in intestinal colonisation and evasion of the host immune system, as well as in encystation and excystation of the parasite.Electronic supplementary materialThe online version of this article (doi:10.1186/s12014-016-9135-8) contains supplementary material, which is available to authorized users.

show abstract

“…In contrast, localization of PI3P to phagosomes in mammalian cells is observed only after their closure (17). Finally, although not much is known about encystation in E. histolytica, wortmannin inhibits encystation in a related reptilian pathogen, E. invadens (18). Therefore, it is possible that E. histolytica encystation also requires PI3K activity.…”

mentioning

confidence: 99%

A Genomewide Overexpression Screen Identifies Genes Involved in the Phosphatidylinositol 3-Kinase Pathway in the Human Protozoan Parasite Entamoeba histolytica

et al. 2014

View full text Add to dashboard Cite

Entamoeba histolytica is a protozoan parasite that causes amoebic dysentery and liver abscess. E. histolytica relies on motility, phagocytosis, host cell adhesion, and proteolysis of extracellular matrix for virulence. In eukaryotic cells, these processes are mediated in part by phosphatidylinositol 3-kinase (PI3K) signaling. Thus, PI3K may be critical for virulence. We utilized a functional genomics approach to identify genes whose products may operate in the PI3K pathway in E. histolytica. We treated a population of trophozoites that were overexpressing genes from a cDNA library with a near-lethal dose of the PI3K inhibitor wortmannin. This screen was based on the rationale that survivors would be overexpressing gene products that directly or indirectly function in the PI3K pathway. We sequenced the overexpressed genes in survivors and identified a cDNA encoding a Rap GTPase, a protein previously shown to participate in the PI3K pathway. This supports the validity of our approach. Genes encoding a coactosin-like protein, EhCoactosin, and a serine-rich E. histolytica protein (SREHP) were also identified. Cells overexpressing EhCoactosin or SREHP were also less sensitive to a second PI3K inhibitor, LY294002. This corroborates the link between these proteins and PI3K. Finally, a mutant cell line with an increased level of phosphatidylinositol (3,4,5)-triphosphate, the product of PI3K activity, exhibited increased expression of SREHP and EhCoactosin. This further supports the functional connection between these proteins and PI3K in E. histolytica. To our knowledge, this is the first forward-genetics screen adapted to reveal genes participating in a signal transduction pathway in this pathogen. E ntamoeba histolytica is an enteric protozoan parasite that causes amoebiasis and amoebic liver abscess in humans (1). It is prevalent in developing countries that cannot prevent its fecaloral spread. E. histolytica enters the human host upon ingestion of water or food contaminated with environmentally stable cysts. After passing through the stomach, excystation leads to the release of trophozoites, which migrate to the bowel lumen for colonization. In 10% of infected individuals, infection can progress from a noninvasive stage to an invasive stage (2), during which the parasite binds to and destroys colonic epithelium. From here, the parasites enter the circulatory system and translocate to other organs. The most common site of extraintestinal infection is the liver, characterized by the formation of amebic liver abscess (ALA).E. histolytica relies on cell motility, phagocytosis, proteolysis of host extracellular matrix, and host cell adhesion for virulence (3). In other eukaryotic cells, these processes are mediated in part by phosphatidylinositol 3-kinase (PI3K) signaling (4). PI3Ks phosphorylate phosphatidylinositol (PI) and its derivatives to generate signaling lipids such as phosphatidylinositol 3-phosphate (PI3P), phosphatidylinositol 3,4-bisphosphate [PI(3,4)P 2 ], phosphatidylinositol 3,5-bisphosphate [PI(3,5)P 2 ]...

show abstract

Inhibition of encystation of Entamoeba invadens by wortmannin

Cited by 19 publications

References 14 publications

Autophagy during Proliferation and Encystation in the Protozoan Parasite Entamoeba invadens

Autophagy during Proliferation and Encystation in the Protozoan Parasite Entamoeba invadens

Proteome analysis of excretory-secretory proteins of Entamoeba histolytica HM1:IMSS via LC–ESI–MS/MS and LC–MALDI–TOF/TOF

A Genomewide Overexpression Screen Identifies Genes Involved in the Phosphatidylinositol 3-Kinase Pathway in the Human Protozoan Parasite Entamoeba histolytica

Contact Info

Product

Resources

About