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Open Access Research article

Functional effect of mir-27b on myostatin expression: a relationship in piedmontese cattle with double-muscled phenotype

Silvia Miretti, Eugenio Martignani, Paolo Accornero and Mario Baratta*

Author Affiliations

Department of Veterinary Science, University of Torino, via Leonardo da Vinci 44, Grugliasco, 10095, Italy

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BMC Genomics 2013, 14:194  doi:10.1186/1471-2164-14-194

Published: 19 March 2013

Abstract

Background

In Piedmontese cattle the double-muscled phenotype is an inherited condition associated to a point mutation in the myostatin (MSTN) gene. The Piedmontese MSTN missense mutation G938A is translated to C313Y myostatin protein. This mutation alters MSTN function as a negative regulator of muscle growth, thereby inducing muscle hypertrophy. MiRNAs could play a role in skeletal muscle hypertrophy modulation by down-regulating gene expression.

Results

After identifying a 3-UTR consensus sequence of several negative and positive modulator genes involved in the skeletal muscle hypertrophy pathway, such as IGF1, IGF1R, PPP3CA, NFATc1, MEF2C, GSK3b, TEAD1 and MSTN, we screened miRNAs matching to it. This analysis led to the identification of miR-27b, miR-132, miR-186 and miR-199b-5p as possible candidates. We collected samples of longissimus thoracis from twenty Piedmontese and twenty Friesian male bovines. In Piedmontese group miR-27b was up-regulated 7.4-fold (p < 0.05). Further, we report that the level of MSTN mRNA was about 5-fold lower in Piedmontese cattle vs Friesian cattle (p < 0.0001) and that less mature MSTN protein was detected in the Piedmontese one (p < 0.0001). Cotransfection of miR-27b and psi-check2 vector with the luciferase reporter gene linked to the bovine wild-type 3-UTR of MSTN strongly inhibited the luciferase activity (79%, p < 0.0001).

Conclusions

These data demonstrate that bovine MSTN is a specific target of miR-27b and that miRNAs contribute to explain additive phenotypic hypertrophy in Piedmontese cattle selected for the MSTN gene mutation, possibly outlining a more precise genetic signature able to elucidate differences in muscle conformation.

Keywords:
MicroRNA; Bovine; Skeletal muscle; Hypertrophy