How is everything controlled?
How is everything controlled? - Regulation of alternative splicing
During an alternative splicing event, different exons are combined in various ways. Which splice sites are chosen depends on interactions between sequences or signals on the mRNA and protein factors which then recruit the spliceosome. Therefore, the process of alternative splicing reflects a complex network of regulatory steps, influenced by a large number of factors and sequences. Splicing enhancers and silencers are sequences on the pre-mRNA which can either lead to the use of a particular splice site or the skipping of this site. These sequences can be located in exons as well as in introns.
Additionally external signals and factors influence the selection of splice sites. Proteins that bind to the pre-mRNA and / or the spliceosome can influence the splicing mechanism. Due to the presence of tissue specific splicing factors (proteins) that promote or inhibit splicing, the pre-mRNA is often spliced differently in different types of tissues, depending on the pattern of regulatory factors expressed in these cells. The same principle is used in different developmental stages of organisms, also providing a different pattern of regulatory factors which control splicing.
