mRNA trans-splicing in the human parasitic cestode Echinococcus multilocularis.

Area of Science:

• Molecular Biology
• Parasitology
• Genetics

Background:

• Trans-splicing is a gene expression mechanism where exons from different RNA molecules are joined.
• Spliced leader (SL) RNAs are involved in trans-splicing in various organisms, including some parasites.
• The parasitic cestode Echinococcus multilocularis serves as a model for studying flatworm biology.

Purpose of the Study:

• To identify and characterize the spliced leader (SL) system in Echinococcus multilocularis.
• To investigate the evolutionary origins and conservation of SL sequences in flatworms.
• To explore the mechanisms of alternative cis/trans-splicing in Echinococcus gene expression.

Main Methods:

• Identification of a conserved 36-nucleotide exon at the 5' termini of Echinococcus multilocularis mRNAs.
• Characterization of a 104-nucleotide SL RNA precursor.
• Sequence comparisons between cestode and trematode SL sequences.
• Analysis of alternative splicing patterns for the echinococcal elp gene.

Main Results:

• A novel 36-nucleotide SL exon was identified in Echinococcus multilocularis, trans-spliced to pre-mRNAs from a SL RNA.
• Cestode and trematode SLs share a common evolutionary origin, but the spectrum of trans-spliced mRNAs differs.
• Alternative cis/trans-splicing of the elp gene depends on the presence or absence of an upstream splice donor site.
• A putative SL gene was found in Echinococcus granulosus, suggesting broad use of trans-splicing in the genus.

Conclusions:

• Trans-splicing is a significant mechanism for gene expression in Echinococcus cestodes.
• The regulation of alternative cis/trans-splicing is linked to intron-exon boundary elements.
• Comparative analysis reveals conserved origins but divergent functions of SL systems in flatworms.