Alternative Splicing

Term in genetics. Alternative splicing is a process that occurs in gene expression and allows a single gene copy to generate several different mRNA transcripts. This leads to the formation of different protein variants from the same gene, which increases genetic diversity and functional diversity in cells. Thanks to alternative splicing, the approximately 23,000 human genes can produce around 90,000 different proteins. The secret behind the genetic flexibility provided by alternative splicing is the so-called Alu elements (short sequences of about 300 base pairs) that can be spliced in and out of genes.

In eukaryotes, a gene is transcribed in a first step in the form of a pre-mRNA. This pre-mRNA contains both exons (the coding sequences) and introns (the non-coding sequences). Before the pre-mRNA is transported into the cytoplasm as so-called mature mRNA, the introns must be removed. This process is called splicing.

In alternative splicing,different exons can be included or excluded from the mature mRNA. This is done by different splicing variants in which introns and pre-mRNA exons are selectively removed or combined at different sites of the pre-mRNA. This results in different mRNA transcripts, which are subsequently translated into different protein variants.

Regulation of splicing: The process of alternative splicing is regulated by a variety of factors, including specific splicing factors and RNA-binding proteins. These factors recognize specific sequences in the pre-mRNA and thus influence which exons are included in the final mRNA.

1. Zhang Y et al. (2021) Alternative splicing and cancer: a systematic review. Signal Transduct Target Ther 6:78.