gms | German Medical Science

Introduction: Posttranscriptional modification by alternative splicing plays a crucial role in the fine-tuning of programmed cell death. This process has been identified to play also a role in several members of the human TRAIL (TNF-related apoptosis inducing ligand) – system. Here we report the identification of a novel alternative splice variant of the antiapoptotic TRAIL receptor 4.

Materials and methods: The expression of TRAIL and the TRAIL receptors TRAIL-R2 and –R4 was analysed by RT-PCR in 10 RCC cell lines of different histological types. The amplification products were subsequently sequenced. Splice donor and –acceptor sites were identified by running the NetGene2 server. Sites of protein modification were analysed by PROSITE scan. Results: All investigated RCC cell lines irrespective of their histological types expressed TRAIL-alpha, -beta, -gamma as well as TRICK2A and 2B.Interestingly, besides the expected TRAIL-R4 amplification product one additional band was coamplified in one of the 10 RCC cell lines. Sequencing, identification of the genomic organisation and computational analysis revealed that the shortened product was a altenative splice variant of TRAIL-R4 which was characterised by a deletion of 114 nucleotides corresponding to exon 3 and therefore designated as TRAIL-R4-beta.

Discussion: The novel TRAIL-R4 splice variant is characterised by the loss of exon 3 which modifies the protein structure due to the lack of the cystein rich domain CRD 1 which seems to play a crucial role in ligand-receptor binding in other TNF family members. This might influence the binding capacity and by this way the signal transduction as well as the antiapoptotic potential in human malignancy.