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Characterization of genes encoding members of the nuclear hormone receptor superfamily from Onchocerca volvulus
R A Yates1, R S Tuan, K J Shepley
1Division of Geographic Medicine, University of Alabama at Birmingham 35294, USA.
Abstract:
Several lines of evidence suggest that molting in parasitic nematodes is controlled through the action of steroid molting hormones, or ecdysones. In other organisms, the central mediator of steroid hormone action is the hormone receptor. These receptor molecules are members of a superfamily of proteins called the nuclear hormone receptor family. Using an oligonucleotide derived from the amino-acid sequence of the Drosophila melanogaster ecdysone receptor, genes encoding homologues of the nuclear hormone receptor family were identified in the genome of the human filarial parasite Onchocerca volvulus. The O. volvulus genome contains at least three genes that encode putative members of the nuclear hormone receptor superfamily. A complete cDNA for one of these genes, designated OvNHR-1, has been isolated and characterized. The OvNHR-1 cDNA was 2378 bp in length, and contained a single open reading frame of 1104 bp. The open reading frame encoded a peptide with all of the features characteristic of a member of the nuclear hormone receptor superfamily of proteins. OVNHR-1 appeared to be encoded by a single-copy gene. Expression of the mRNA corresponding to OvNHR-1 was developmentally regulated, with maximal expression occurring during early embryogenesis. The polypeptide encoded by the OvNHR-1 open reading frame is antigenic in a minority of individuals exposed to O. volvulus.
Insights
Researchers identified a novel nuclear hormone receptor gene, OvNHR-1, in the parasitic worm Onchocerca volvulus. This gene is crucial for development and may be involved in the parasite's molting process.
Area of Science:
- Parasitology
- Molecular Biology
- Genomics
Background:
- Molting in parasitic nematodes is regulated by steroid hormones like ecdysones.
- Nuclear hormone receptors mediate steroid hormone action in various organisms.
- Understanding these pathways is key to controlling parasitic infections.
Purpose of the Study:
- To identify and characterize nuclear hormone receptor family members in the filarial parasite Onchocerca volvulus.
- To investigate the role of these receptors in parasite development and molting.
Main Methods:
- Oligonucleotide probes based on the Drosophila melanogaster ecdysone receptor were used.
- Gene identification and sequencing were performed on the O. volvulus genome.
- cDNA isolation and characterization of OvNHR-1 were conducted.
- Analysis of gene expression and protein antigenicity.
Main Results:
- At least three nuclear hormone receptor superfamily genes were found in O. volvulus.
- A complete cDNA for OvNHR-1 was isolated and characterized (2378 bp).
- OvNHR-1 encodes a protein with characteristic nuclear hormone receptor features and is likely a single-copy gene.
- OvNHR-1 mRNA expression is developmentally regulated, peaking during early embryogenesis.
- The OvNHR-1 protein is antigenic in some individuals infected with O. volvulus.
Conclusions:
- The discovery of OvNHR-1 provides a potential target for understanding and controlling Onchocerca volvulus development.
- OvNHR-1's developmentally regulated expression suggests a critical role in parasite life cycle progression.
- The antigenicity of OvNHR-1 indicates its potential relevance for diagnostics or vaccine development against filariasis.