Article,
Molecular characterization of a serum-responsive, DAF-12-like nuclear hormone receptor of the fox-tapeworm Echinococcus multilocularis
Journal of Cellular Biochemistry, (February 2011)PMID: 21328613.
DOI: 10.1002/jcb.23073
Abstract
As the primary mediators of lipophilic and steroid hormone signalling, the family of nuclear receptors plays a central role in the regulation of metazoan development. Lipophilic hormones are also thought to be important players in the molecular interaction between larval cestodes and their hosts but no member of the nuclear receptor family has yet been characterized in this group of parasites. In this work, we provide for the first time evidence for the presence of nuclear receptors in cestodes of the genus Echinococcus. By bioinformatic analyses, we identified a set of 17 nuclear receptors in the genomes of E. multilocularis and E. granulosus which broadly overlapped with the set of nuclear receptors that is expressed by schistosomes, but also contained several members that are unique to cestodes. One of these receptors, EmNHR1, displayed structural homologies to the DAF-12/HR-96 subfamily of nuclear receptors that regulates cholesterol homeostasis and longevity in metazoans. By RT-PCR analyses, we demonstrate that the EmNHR1 encoding gene is expressed in all Echinococcus larval stages that are involved in the infection of the intermediate host. By yeast two-hybrid analyses, we further demonstrate cross-communication between EmNHR1 and TGF-ß signalling pathways in Echinococcus and that mammalian serum contains a ligand that induces homodimerization of the EmNHR1 ligand binding domain. EmNHR1 could thus play an important role in hormonal host-parasite cross-communication mechanisms during an infection. On the basis of our results, further investigations into the role of nuclear receptor signalling in cestode development and host-parasite interaction will be greatly facilitated. J. Cell. Biochem. © 2011 Wiley-Liss, Inc.
