Evaluation of the effect of bovine variants of the MSTN gene on pre-mRNA splicing

The myostatin protein is a powerful negative regulator of skeletal muscle growth encoded by the MSTN gene. When this gene malfunctions—due to certain variants—the brake no longer plays its role. Thus, variants that cause a loss of MSTN function lead to a particular bovine phenotype characterized by increased skeletal muscle mass, known as “double muscling” or “double muscularity.”

Several variants of the MSTN gene have been associated with this phenotype, but most of them have not been experimentally validated. This is the case, for example, with five missense variants of MSTN reported in the scientific literature, for which the mechanism by which they negatively impact the gene is unknown. These variants have the potential to disrupt several processes essential for gene expression. Among them, the splicing process is involved in RNA maturation and is essential for the synthesis of functional proteins. During splicing, introns are excised from immature RNAs and exons are fused together to produce mature RNA.

In this study, the researchers developed a functional test to assess the impact of MSTN variants on splicing. They analyzed the five missense variants associated with the “double muscular” phenotype mentioned above, as well as a previously known splicing variant used as a positive control.

They also tested two artificial intelligence-based computational tools capable of predicting whether a variant is likely to disrupt splicing.

The results show that:

• the five false-sense variants studied do not affect RNA splicing;
• the positive control variant does alter splicing as expected;
• the bioinformatic predictions correspond perfectly to the results obtained experimentally.

Researchers from the GBOS team have developed a reliable functional test to analyze splicing variants of the MSTN gene in cattle. They also show that artificial intelligence tools can help to quickly identify variants with a potential effect on MSTN splicing.

Contact : Arnaud Boulling

Reference :
Gaiani N., Rocha D., Boulling A. Assessing the effect of bovine MSTN variants on pre-mRNA splicing Animal Genetics https://doi.org/10.1002/age.70073