Abstract
WFIKKN2 may play a role in the regulation of muscle growth and development, but to date there have been no reports on the effect of variation in WFIKKN2 on growth and carcass traits in livestock. In this study, the effect of variation in ovine WFIKKN2 was investigated in 800 New Zealand Romney lambs (395 male and 405 female), with five previously described variants (A to E) being identified. Variation in ovine WFIKKN2 was not found to affect various growth traits in the female lambs, but the presence of variant B was associated (P < 0.05) with decreased birth weight, tailing weight, weaning weight and pre-weaning growth rate; and increased post-weaning growth rate in male lambs. In male lambs, the presence of variant B was associated (P < 0.05) with an increased shoulder yield and proportion shoulder yield. No associations with growth or carcass traits were detected for the presence (or absence) of the other variants. These results suggest that variation in ovine WFIKKN2 may have a differential effect on growth in male and female lambs, and hence that the gene may be expressed in, or act in, a gender-specific fashion.
Highlights
Myostatin is a regulator of myogenesis and acts primarily as a negative regulator of muscle growth in mammals
It has been revealed experimentally that the WFIKKN1 and WFIKKN2 proteins can inhibit the biological activity of myostatin by binding to the extracellular domain (ECD) of the myostatin receptor protein[9,10,11,12]
The observation that WFIKKN2 was found to have a higher affinity than WFIKKN1 for the myostatin receptor, suggests that WFIKKN2 is a more effective receptor agonist[10]
Summary
Myostatin ( known as growth and differentiation factor 8, GDF8) is a regulator of myogenesis and acts primarily as a negative regulator of muscle growth in mammals. Deletions or mutations in the myostatin gene (MSTN) cause an increase in skeletal muscle mass as a result of a combination of hypertrophy (an increase in the size of muscle fibres) and hyperplasia (an increase in the number of muscle fibres) This effect has been recorded in sheep[1], cattle[2,3,4], dogs[5], mice[6] and humans[7]. Investigations into the action of myostatin have led to the discovery of other proteins that affect its activity These include WFIKKN1 ( called growth and differentiation factor associated serum protein-2, GASP2) and WFIKKN2 ( called GASP1). Using surface plasmon resonance assays in a solution-competition format, Szlama et al.[11] revealed that 50 nM WFIKKN1 and WFIKKN2 caused an 80% and 90% decrease respectively in the rate of association of myostatin with its receptor ECD. Studies have revealed that WFIKKN2 has a high level of expression in the skeletal muscle of mice[9,14,15] and in developing human foetal tissues[16]
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