The Regulation Of The Alternative Splicing Of Bcl-X Pre-mRNA

The alternative splicing of pre-mRNA is a fundamental mechanism of differential gene expression in terms of giving rise to functionally distinct proteins from single gene, according to the developmental and environmental stimulus states in multicellular organisms. Bcl-X, a member of Bcl-2 family, plays an important role in cell proliferation, differentiation and apoptosis. Alternative splicing of Bcl-X gives rise to several mRNA isoforms, in particular the two variants BcI-X_l and -Xs, which can produce proteins with atagonistic functions in cellular apoptosis. However, it remains unclear how Bcl-X pre-mRNA splicing is regulated by extracellular factors controlling cell growth, apoptosis, and differentiation.In this study, we explored the effect of cytokine IL-6, GM-CSF, IL-11 and TPA on the regulation of the alternative splicing of Bcl-X in K562 cells and U251 cells. At the same time, the effect of TPA and DMSO on the induce-differentiation of human lung adenocarcinoma GLC cells and the alternative splicing of Bcl-X in GLC cells were identified.The results of experiments were as following .(一) The experiment results revealed that the proliferation of GLC cells was apparently inhibited after being treated with TPA and DMSO, the cell growth inhibitory rate was 25%, the mitotic index was decreased to 26‰. Optical microscope, scanning electron microscope and transmission electron microscope observation showed that restorational morphology and structure changes similar to those of normal cell occurred in the GLC cells treated with TPA and DMSO, the volume of cells increased, nucleo-cytoplasmic ratio decreased, the number, volume, structure of mitochondrion appeared consistent, Golgi complex becoming typical, endoplasmic reticulum increased, microvilli and filopodia reduced. Furthermore, RT-PCR and Western blot assay revealed that TPA and DMSO repressed the Bcl-X_L inclusion, and made the shift in splicing from BcI-Xl to Bcl-Xs in GLC cells.(二) TPA activated the PKC signal system increased the Bcl-X_L inclusion in U251 cells, the biological effect of TPA was restored by breviscapin which inhibited the functions of PKC. But breciscapin treatment decreased Bcl-X_L inclusion. To...