The research “SR Proteins Induce Alternative Exon Skipping through Their Activities on the Flanking Constitutive Exons” conducted by Joonhee Han, and other analysts present a study of SR proteins involved in RNA splicing. The hypothesis of the study was stated as follows: whether SR protein-mediated exon inclusion or skipping events have the same or different mechanisms. Researchers also intended to study the impact of SR proteins on a kinetic coupling between transcription and cotranscriptional RNA splicing because there was a proven effect of SR proteins on transcriptional elongation. The hypothesis was based on the assumption that SR proteins contribute to exon insertion in controlled splicing through exonic splicing enhancers. Moreover, the evaluation of studies revealed that other researchers proved that SR proteins trigger exon skipping but did not discuss the mechanism of these proteins.
To research the hypothesis, analysts utilized the CaMKIIδ gene as a sample to investigate the function of SR protein-mediated exon inclusion or skipping. Besides, researchers used mouse embryonic fibroblasts (MEFs) deduced from conditional SRSF1 and SRSF2 knockout mice to assess CaMKIIδ mRNA isoform change in reaction to SR protein exhaustion. The CaMKIIδ gene was also used to study which how SR proteins participate in tissue-specific alternative splicing in cooperation with other tissue-specific RNA linking splicing controllers.
There were several steps of analysis; the results of those were illustrated in figures. Firstly, CaMKIIδ gene differential (or alternative) splicing in reaction to SR protein reduction in MEFs was investigated. Afterward, analysts proposed an exon strength examination on a splicing reporter. The third figure presented a mutational study of CaMKIIδ gene differential splicing. Fourthly, an evocation of exon skipping or inclusion process by a tied RS domain was shown. The fifth figure illustrated the induction of CaMKIIδ alternative splicing by ectopic expression of tissue-specific splicing controllers and their synergetic effect with SR protein reduction.
Overall, the results of the research show that there is a growth in exon inclusion in reaction to the transient reduction of SR proteins in MEFs. Therefore, it was found out that SR proteins are included in regulated CaMKIIδ splicing in various kinds of cells. Furthermore, it was discovered that in MEFs reduction of SRSF2 is more efficient than SRSF1 in impelling CaMKIIδ splicing, while SRSF1 reduction had a more significant impact on evolving heart. Besides, it was detected that the hyperexpression of RBFOX protein or exhaustion of an SR protein both fractionally caused CaMKIIδ alternative splicing in MEFs. Mouse embryo fibroblasts obtained from conditional SR protein of knockout mice demonstrated that SR protein-caused exon skipping varies by their dominant actions on a flanking constitutive exon and demands synergy of several SR proteins.
To conclude, findings of the mechanism of SR proteins splicing connected with researched guidelines for SR proteins contributed to the development of a framework that explains the complex impact of SR protein-controlled splicing in mammals. Researchers also proved that unique heart-related CaMKIIδ gene splicing could be reproduced in fibroblasts with the help of adjusting SR proteins down and an RBFOX protein adjusting up. Furthermore, the hyperexpression of SR protein reduces controlled CaMKIIδ splicing and differentiation of neurons in P19 cells. These findings show that SR protein-dependent exon skipping may represent the most significant way for gaining synergetic effect with other splicing regulators in creating tissue-specific alternative splicing that is inevitable for cell differentiation processes.
Reference
Han, J., Ding, J., Byeon, C. W., Kim, J. H., Hertel, K. J., Jeong, S., & Fu, X. (2011). SR proteins induce alternative exon skipping through their activities on the flanking constitutive exons. Molecular and Cellular Biology, 31(4), 793-802. Web.