Article

Emetine resistant mutants of Entamoeba histolytica overexpress mRNAs for multidrug resistance.

Department of Tropical Public Health, Harvard School of Public Health, Boston, MA.
Archivos de investigación médica 02/1990; 21 Suppl 1:183-9.
Source: PubMed

ABSTRACT Although drug therapy is critical for control of amoebiasis, little is known about mechanisms of drug resistance by E. histolytica parasites. Here we tested the hypothesis that multidrug resistant (mdr) amoeba mutants, similar to mdr tumor cells, are drug resistant based upon overexpression of a P-glycoprotein pump that effluxes drugs from the cells. Using primers to conserved regions of the human P-glycoprotein and the polymerase chain reaction (PCR), we identified multiple 344 base par segments of amoeba DNA similar to the mammalian P glycoprotein. The amino acid sequences of amoeba mdr-like PCR products were from 53 to 97 identical with each other, 55 to identical to human mdr1 sequences, and 41-44% identical with P. falciparum mdr-like sequences. On northern blots, the mdr-like PCR products identified amoeba mRNAs 4.5-5 kilobases long, similar to the 5 kilobase mRNAs reported for the mammalian mdr gene. These mRNAs were increased at least seven times in emetine resistant mutant clone C2 amoebae versus wild-type clone A parasites. Further, the expression of the mdr-like mRNAs was increased three to four times when clone C2 mutants were grown under drug pressure versus the same parasites grown without emetine. In contrast, the number of genomic copies of the mdr-like DNA segments was not increased in the mutant clone C2 versus the wild-type clone A amoebae, and no rearrangements of the mdr-like DNA segments by the mutant were identified on Southern blots. In conclusion there appears to be a family of mdr-like genes in E. histolytica, which may be involved in drug resistance by the parasite.

2 Followers
 · 
181 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Developmental switching between life-cycle stages is a common feature among many pathogenic organisms. The protozoan parasite Entamoeba histolytica converts between cysts (essential for disease transmission) and trophozoites (responsible for tissue invasion). Identification of genes involved in the developmental pathway has been severely hindered by the inability to generate E. histolytica cysts in vitro. Using parasite strains derived from recent human infections and whole-genome transcriptional profiling, we determined that 1439 genes (approximately 15% of annotated genes) were potentially developmentally regulated. Genes enriched in cysts (672 in total) included cysteine proteinases and transmembrane protein kinases, which may be involved in signal transduction. Genes enriched in trophozoites (767 in total) included genes typically thought of as important in tissue invasion by trophozoites, including the Gal/GalNAc lectin light subunit and cysteine protease 1. Putative regulators of differentiation including possible G-protein coupled receptors, signal transduction proteins and transcription factors were identified. A number of E. histolytica stage-specific genes were also developmentally regulated in the reptilian parasite E. invadens, indicating that they likely have conserved functions in Entamoeba development. These advances lay the groundwork for dissection of the molecular signals that initiate stage conversion and development of novel diagnostic and therapeutic measures targeting E. histolytica cysts.
    Cellular Microbiology 07/2007; 9(6):1426-44. DOI:10.1111/j.1462-5822.2006.00882.x · 4.82 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To investigate the theoretical model of the three-dimensional structure of multidrug resistance protein 1(P-glycoprotein, expressed by MDR1 gene of E. histolytica) and its molecular docking with anti-amoebic agents. The theoretical model of multidrug resistance protein 1(P-glyoprotein, expressed by MDR1 gene of E. histolytica) was predicted by homology modeling on the structure of the 3G61. Docking studies were performed to investigate the interaction of p-glycoprotein with antiamoebic gents. MRPEH1F is significant model for p-glycoprotein and have total of 114 amino acid residues. The model is well supported by cross validation data generated after analyzing criss-cross residues, local geometry check as well as ramachandran plot. Molecular docking of MRPEH1F revealed that all the test molecules have strong binding affinity along with significant interactions. Henceforth, none of the molecules will probably be effective for the multidrug resistant strains of E. histolytica.
    Current topics in medicinal chemistry 05/2015; 15(10). DOI:10.2174/1568026615666150317222927 · 3.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: With the goal of understanding possible mechanisms of drug resistance by the protozoan parasite Entamoeba histolytica (Eh), two novel Eh P-glycoprotein (Pgp) genes (Eh pgp5 and Eh pgp6) were sequenced, and the expression of four Eh pgp genes determined in wild-type (wt) clone A and emetine-resistant (EmR) clone C2 amebae. The Eh pgp5 gene encodes a 1301-amino acid (aa) protein that is similar to those of Eh pgp1 (64% aa identity), Eh pgp2 (61%), Eh pgp6 (39%) and Homo sapiens MDR (multidrug-resistance-encoding)(Hs MDR1; 38%) genes. The 1282-aa Eh pgp6 open reading frame (ORF), which is 19-28 aa shorter than those encoded by other Eh pgp, is also similar to those of Eh pgp1 (46% aa identity), Eh pgp2 (38%), and Hs MDR1 (39%). Both Eh pgp5 and Eh pgp6 ORF predict two ATP-binding cassettes and twelve hydrophobic alpha-helices, which form the putative transmembrane channel. EmR clone C2 amebae, growing at all concentrations of drug, show increased amounts of Eh pgp1 and Eh pgp6 mRNA when compared to wt clone A amebae. In contrast, only clone C2 amebae selected for growth at the highest concentrations of emetine (100-200 micrograms/ml) show increased Eh pgp5 mRNA, while mRNA of both clone C2 and clone A Eh amebae fail to bind an Eh pgp2-specific probe. It appears then that multiple Pgp may contribute to amebic Em resistance in vitro.
    Gene 11/1995; 164(1):179-84. DOI:10.1016/0378-1119(95)00533-C · 2.08 Impact Factor