Trans-splicing

Trans-splicing is a special form of RNA processing where exons from two different primary RNA transcripts are joined end to end and ligated. It is usually found in eukaryotes and mediated by the spliceosome, although some bacteria and archaea also have 'half-genes' for tRNAs. Trans-splicing is a special form of RNA processing where exons from two different primary RNA transcripts are joined end to end and ligated. It is usually found in eukaryotes and mediated by the spliceosome, although some bacteria and archaea also have 'half-genes' for tRNAs. Whereas 'normal' (cis-)splicing processes a single molecule, trans-splicing generates a single RNA transcript from multiple separate pre-mRNAs. This phenomenon can be exploited for molecular therapy to address mutated gene products. Trans-splicing can be the mechanism behind certain oncogenic fusion transcripts. Some fusion transcripts also occur via trans-splicing in normal human cells. Trans-splicing is used by certain microbial organisms, notably protozoa of the Kinetoplastae class to express genes. In these organisms, a capped splice leader (SL) RNA is transcribed; simultaneously, genes are transcribed in long polycistrons. The capped splice leader is trans-spliced onto each gene to generate monocistronic capped and polyadenylated transcripts. These early-diverging eukaryotes use few introns, and the spliceosome they possess show some unusual variations in their structure assembly. They also possess multiple eIF4E isoforms with specialized roles in capping. Some other eukaryotes, notably nematodes, also frequently use trans-splicing.