The protozoan parasite Entamoeba histolytica causes an estimated 50 million cases of invasive disease annually. The most common manifestations of amebic infection are colonic disease and liver abscesses. Our goal is to identify novel virulence determinants in E. histolytica with the aim of understanding the molecular basis of amebic pathogenesis. We have previously developed and used microarray technology to identify genes whose expression is restricted to virulent strains and conditions. One such gene, encoding an E. histolytica serine, threonine, isoleucine, rich protein (EhSTIRP) is expressed only in virulent strains and conditions and has very low to no expression in non-virulent strains and conditions. Preliminary data indicate that parasites in which EhSTIRP is downregulated have decreased adhesion and virulence in vitro. Additionally, in EhSTIRP downregulated parasites have reduced expression of cytoskeletal genes. Our hypothesis is that EhSTIRP is a key virulence determinant in E. histolytica with potential roles in parasite adhesion and signaling relevant to amebic pathogenesis. We propose to further characterize the contribution of EhSTIRP to E. histolytica virulence in vitro, determine whether EhSTIRP is necessary for virulence in vivo, identify the localization of EhSTIRP during host invasion, characterize domains of EhSTIRP with relevance to parasite virulence, and identify amebic proteins that interact with EhSTIRP. We will use genetic and biochemical approaches to dissect gene function, live cell imaging to determine EhSTIRP localization during amebic host cell interaction and microarray analysis to define parasite transcriptome changes associated with genetic manipulation of EhSTIRP. These approaches promise to identify the role of EhSTIRP in amebic pathogenesis and dissect the genetic and biochemical network that is associated with EhSTIRP and which regulates virulence in Entamoeba histolytica.

Public Health Relevance

Entamoeba histolytica is an important pathogen and has an impact on human health on a global scale. The main disease manifestations are dysentery and liver abscesses. Although the majority of disease is in developing countries, this parasite can cause infections anywhere that water purification systems get adversely affected. Events such as the Tsunami or upheaval in the political and social infrastructure of a region can allow disease to emerge. We are interested in understanding the molecular mechanisms that the parasite uses to cause disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI053724-10
Application #
8282875
Study Section
Special Emphasis Panel (ZRG1-IDM-H (03))
Program Officer
Mcgugan, Glen C
Project Start
2002-12-01
Project End
2014-05-31
Budget Start
2012-06-01
Budget End
2014-05-31
Support Year
10
Fiscal Year
2012
Total Cost
$387,332
Indirect Cost
$142,307
Name
Stanford University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305
Pompey, Justine M; Morf, Laura; Singh, Upinder (2014) RNAi pathway genes are resistant to small RNA mediated gene silencing in the protozoan parasite Entamoeba histolytica. PLoS One 9:e106477
Pearson, Richard J; Morf, Laura; Singh, Upinder (2013) Regulation of H2O2 stress-responsive genes through a novel transcription factor in the protozoan pathogen Entamoeba histolytica. J Biol Chem 288:4462-74
Zhang, Hanbang; Ehrenkaufer, Gretchen M; Hall, Neil et al. (2013) Small RNA pyrosequencing in the protozoan parasite Entamoeba histolytica reveals strain-specific small RNAs that target virulence genes. BMC Genomics 14:53
Morf, Laura; Pearson, Richard J; Wang, Angelia S et al. (2013) Robust gene silencing mediated by antisense small RNAs in the pathogenic protist Entamoeba histolytica. Nucleic Acids Res 41:9424-37
Lin, Audrie; Bik, Elisabeth M; Costello, Elizabeth K et al. (2013) Distinct distal gut microbiome diversity and composition in healthy children from Bangladesh and the United States. PLoS One 8:e53838
Zhang, Hanbang; Pompey, Justine M; Singh, Upinder (2011) RNA interference in Entamoeba histolytica: implications for parasite biology and gene silencing. Future Microbiol 6:103-17
Zhang, Hanbang; Alramini, Hussein; Tran, Vy et al. (2011) Nucleus-localized antisense small RNAs with 5'-polyphosphate termini regulate long term transcriptional gene silencing in Entamoeba histolytica G3 strain. J Biol Chem 286:44467-79
Pearson, Richard J; Singh, Upinder (2010) Approaches to characterizing Entamoeba histolytica transcriptional regulation. Cell Microbiol 12:1681-90
Baxt, Leigh A; Rastew, Elena; Bracha, Rivka et al. (2010) Downregulation of an Entamoeba histolytica rhomboid protease reveals roles in regulating parasite adhesion and phagocytosis. Eukaryot Cell 9:1283-93
Vicente, Joao B; Ehrenkaufer, Gretchen M; Saraiva, Ligia M et al. (2009) Entamoeba histolytica modulates a complex repertoire of novel genes in response to oxidative and nitrosative stresses: implications for amebic pathogenesis. Cell Microbiol 11:51-69

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