title: Cloning of Schistosoma mansoni Seven in Absentia (SmSINA)(+) homologue cDNA, a gene involved in ubiquitination of SmRXR1 and SmRXR2.
abstract: Drosophila (SINA) and human Seven in Absentia (SIAH-1 and SIAH-2) have been implicated in ubiquitin-mediated proteolysis of different target proteins. Using the Schistosoma mansoni nuclear receptor SmRXR2 as bait in a yeast two-hybrid system, we identified a DNA fragment that encodes part of the schistosome homologue of the Seven in Absentia protein (SmSINA). Screening of S. mansoni cDNA expression library resulted in the isolation of a cDNA containing the full-length coding region of SmSINA. SmSINA contains the characteristic structural features of other SINA proteins including a conserved N-terminal RING finger domain and a cysteine-rich C-terminus. We demonstrate that SmSINA associates with SmRXR2 and SmRXR1 both in vivo and in vitro, and define the binding domains in SmRXR2 and SmRXR1 that mediate their interaction. Schistosome SINA co-localizes with SmRXR2 and SmRXR1 in vitelline cells. In addition, we show that SmSINA stimulates the ubiquination of both SmRXR2 and SmRXR1 in vitro. Our findings suggest that SmSINA regulates ubiquitination and ubiquitin-induced degradation of schistosome nuclear receptors (RXR1 and RXR2) via the ubiquitin-proteasome pathway.
authors.affiliation: Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, School of Medicine and Biomedical Sciences, 138 Farber Hall, State University of New York, Buffalo, NY 14214, USA.
authors.forename: Marcelo R
authors.initials: MR
authors.lastname: Fantappié
authors.forename: Ahmed
authors.initials: A
authors.lastname: Osman
authors.forename: Christer
authors.initials: C
authors.lastname: Ericsson
authors.forename: Edward G
authors.initials: EG
authors.lastname: Niles
authors.forename: Philip T
authors.initials: PT
authors.lastname: LoVerde
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005786:Gene Expression Regulation; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D018168:Receptors, Retinoic Acid / Q000378:metabolism*; D047488:Retinoid X Receptors; D012550:Schistosoma mansoni / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000378:metabolism*
chemical_list: D018076:DNA, Complementary; D015801:Helminth Proteins; C120371:RXR-2 protein, Schistosoma mansoni; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D014157:Transcription Factors; D025801:Ubiquitin; C480686:seven in absentia protein, Schistosoma mansoni