Investigation on the 19S ATPase proteasome subunits (Rpt1–6) conservation and their differential gene expression in Schistosoma mansoni

Abstract

The ubiquitin-proteasome system is responsible for degradation of the majority of intracellular proteins in eukaryotic cells. The 26S proteasome proteolytic complex is composed of a 20S core particle responsible for protein degradation and the 19S lid which plays a role in the recognition of polyubiquitinated substrates. The 19S regulatory particle (Rps) is composed of ATPase (Rpt) and non-ATPase (Rpn) subunits. In this study, we analyzed the expression profile of 19S Rpt subunits in the larvae and adult stage of the Schistosoma mansoni life cycle. Conventional reverse transcriptase polymerase chain reaction (RT-PCR) revealed that the majority of the 19S Rpt subunits amplified at the expected molecular masses for various investigated stages. In addition, SmRpt1, SmRpt2, and SmRpt6 transcript levels were increased in 3 h-cultured schistosomula and reasonably maintained until 5 h in culture, as revealed by qRT-PCR. Phylogenetic analysis of 19S Rpt subunits showed high structural conservation in comparison to other Rpt orthologues. The mRNA expression profile of 19S Rpt subunits did not correlate with 26S proteasome proteolytic activity as judged by a (14)C-casein-degrading assay, in the early cultured schistosomula. Taken together, these results revealed a differential expression profile for 19S Rpt subunits whose transcript levels could not be directly associated to 26S proteasome activity.

Conservation and developmental expression of ubiquitin isopeptidases in Schistosoma mansoni

“…Although UCH-L5 can cleave polyubiquitin when bound to the proteasome, this reaction may require the participation of additional proteasome components to partially unfold the polyubiquitin chain ( Eletr & Wilkinson 2011 ). We detected low levels of UCH-L5 expression in the cercaria stage, in agreement with the previous results from our group that demonstrated decreased 26S proteasome activity in extracts from cercariae relative to adult worms ( Pereira-Júnior et al 2012 ).…”

“…Given that protein homeostasis and cell signalling often require tight temporal and spatial regulation, the DUBs affecting these pathways are also regulated in many different ways. Previous results from our group have demonstrated that the accumulation of ubiquitinated conjugates in cercariae correlated with decreased 26S proteasome activity at this stage ( Guerra-Sá et al 2005 , Pereira-Júnior et al 2012 ).…”

Heat shock protein 70 (Hsp70) in Schistosoma mansoni and its role in decreased adult worm sensitivity to praziquantel

“…Different studies revealed the importance of controlled protein turnover in the ubiquitin-proteasome system during development of Schistosoma worms (Mathieson et al ., 2011; Pereira-Júnior et al ., 2013). Proteasomes are found to be an important system involved in the stress response in S. mansoni adult worms (de Paula et al ., 2015).…”