Characterisation of the COP9 signalosome in Schistosoma mansoni parasites.

The COP9 signalosome (CSN) is an eight-subunit complex found in all eukaryotes and shares structural features with both the 26S proteasome 'lid' and translation factor eIF3. Recent data have demonstrated that the CSN is a regulator of the ubiquitin (Ub) proteasome system (UPS). CSN controls substrate ubiquitination by cullin-RING Ub ligases, a step which determines substrate specificity of the UPS. Here, we reconstructed the CSN complex in Schistosoma mansoni and identified eight homologous components. Among these homologues, five subunits were predicted with their full-length sequences. Phylogenetic analysis confirmed the evolutionary conservation and the architecture of CSN, as well as the 26S proteasome 'lid'. We performed quantitative reverse transcription-polymerase chain reaction to detect the expression of the SmCSN transcripts. The Smcsn1, Smcsn2, Smcsn3, Smcsn4, Smcsn5, Smcsn6, Smcsn7 and Smcsn8 genes were up-regulated in adult worms compared to cercariae, and the expression levels were similar to that of in vitro cultivated schistosomula. Taken together, these results suggest that the CSN complex may be important during cercariae, schistosome and adult worm development and might explain, at least in part, the differences among UPSs during the parasite life cycle.