A 3' UTR polymorphism g.1618 G > A in the MAFA gene modulates miR-3678-3p binding and enhances meat production in sheep via the MAFA/GHR/JAK2 pathway.

backgroundMAFA (musculoaponeurotic fibrosarcoma oncogene Family A) is a specific transcriptional activator of the insulin gene (INS), playing a critical role in regulating insulin secretion and thereby indirectly influencing growth and development in animals. Previously, MAFA's role in meat production remained speculative, despite its known function in endocrine regulation. However, our recent publication provides direct evidence linking MAFA to muscular phenotypes in sheep. These findings support a direct role for MAFA in muscle growth, complementing its canonical role in insulin-mediated growth regulation. To further investigate this proposition, we conducted genotype-phenotype association analyses to assess the potential impact of MAFA polymorphisms on meat production performance in sheep. In parallel, we employed a combination of dual-luciferase reporter assays, transcriptome profiling, and ChIP-PCR to dissect the underlying molecular mechanisms. These findings were further validated in ovine myoblasts.

resultsWe found that the g.1618 G/A polymorphism in the 3' UTR of the MAFA gene is associated with meat production in sheep. Individuals with the GG genotype exhibited a 36.9% higher proportion of longissimus dorsi muscle mass compared to those with the AA genotype. Further analysis, including binding site prediction and dual-luciferase reporter assays, revealed that this mutation may regulate MAFA translation efficiency by altering the binding affinity of miR-3678-3p. Subsequently, ChIP-PCR experiments confirmed that the growth hormone receptor (GHR) gene is a direct target of the transcription factor MAFA. By conducting miR-3678-3p transfection and MAFA overexpression experiments in sheep myoblasts, we further validated the miR-3678-3p/MAFA/GHR regulatory axis and the classical GHR/JNK signaling pathway. These findings elucidate the molecular mechanism by which the g.1618 G/A polymorphism in the MAFA gene affects meat production in sheep, providing a novel molecular marker with potential application in molecular breeding for improved meat performance in sheep.

conclusionsIn summary, The G/A polymorphism at position g.1618 in the 3' UTR of the MAFA gene affects the binding of miR-3678-3p, thereby regulating the expression of the transcription factor MAFA at the post-transcriptional level. MAFA, in turn, directly influences the transcription of its target gene GHR, which affects JAK2 phosphorylation, ultimately regulating myoblast proliferation and muscle growth.