Regulation of alternative splicing of Bcl-x by IL-6, GM-CSF and TPA.

The splicing of many alternative exons in the precursor messenger RNA (pre-mRNA) is regulated by extracellular factors but the underlying molecular bases remain unclear. Here we report the differential regulation of Bcl-x pre-mRNA splicing by extracellular factors and their distinct requirements for pre-mRNA elements. In K562 leukemia cells, treatment with interleukin-6 (IL-6) or granulocyte-macrophage colony stimulating factor (GM-CSF) reduced the proportion of the Bcl-xL variant mRNA while treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) had no effect.

[Regulation of pre-mRNA alternative spicing in U251 cells by TPA].

By using the mini-gene construct containing partial sequence of Bcl-X gene as model, we examined the function of TPA on Bcl-X pre-mRNA alternative splicing in vivo and vitro with RT-PCR and site-directed mutagesis assay. The results show that PKA signaling system can regulate Bcl-X pre-mRNA alternative splicing, the possible mechanism is that the responsible sequence affect the choice of the 5'-downstream or upstream splice site of Bcl-X pre-mRNA.