DcpS, a general modulator of cap-binding protein-dependent processes?

The DcpS scavenger decapping enzyme carries out the final step of the 3' to 5' end mRNA decay pathway by clearing the cell of residual cap structure that would otherwise accumulate. Its ability to modulate cap structure accumulation in a cell implies that DcpS could influence the pool of available cap-binding proteins and in turn impact their downstream functions. Since the 5' cap and corresponding cap-binding proteins are integral components of various aspects of mRNA metabolism including pre-mRNA splicing, nuclear export, translation and decay, DcpS has been proposed as a possible regulator of these processes. There is now increasing evidence that DcpS could impact at least some of these events. Indeed, DcpS can regulate the cap-dependent first intron pre-mRNA splicing in mammalian cells and a DcpS ortholog is important for 5' to 3' exonucleolytic activity in yeast. Moreover, the nucleocytoplasmic shuttling property of DcpS indicates that it could function as a regulator of cap-dependent processes in both cellular compartments by buffering cap structure concentrations and the resulting availability of cap-binding proteins in a cell. In this review, we discuss known and potential roles of DcpS in mRNA metabolism.