Construction of a eukaryotic expression vector for pEGFP-FST and its biological activity in duck myoblasts

Background Follistatin (FST), a secreted glycoprotein, is intrinsically linked to muscle hypertrophy. To explore the function of duck FST in myoblast proliferation and differentiation, the pEGFP-FST eukaryotic expression vector was constructed and identified. The biological activities of this vector were analyzed by transfecting pEGFP-FST into cultured duck myoblasts using Lipofectamine™ 2000 and subsequently determining the mRNA expression profiles of FST and myostatin (MSTN). Results The duck pEGFP-FST vector was successfully constructed and was confirmed to have high liposome-mediated transfection efficiency in duck myoblasts. Additionally, myoblasts transfected with pEGFP-FST had a higher biological activity. Significantly, the overexpression of FST in these cells significantly inhibited the mRNA expression of MSTN (a target gene that is negatively regulated by FST). Conclusions The duck pEGFP-FST vector has been constructed successfully and exhibits biological activity by promoting myoblast proliferation and differentiation in vitro.

Molecular cloning and expression pattern of duck Six1 and its preliminary functional analysis in myoblasts transfected with eukaryotic expression vector.

Skeletal muscle development is regulated by Six1, an important myogenic transcription factor. However, the functional analysis of duck Six1 has not been reported. Here, we cloned the coding domain sequence (CDS) region of the duck Six1 gene using RT-PCR and RACE methods. Bioinformatics analysis revealed that duck Six1 CDS region comprised of 849 bp and encoded 282 amino acids and had a high degree of homology with other species, suggesting that the functions of duck Six1 gene are conserved among other animals. Real-time PCR used to determine the mRNA expression profiles of duck Six1 in different tissues and different developmental stages showed that Six1 was highly expressed in skeletal muscle and the embryonic stage. Furthermore, the eukaryotic expression vector pEGFP-duSix1 was constructed and transfected into the duck myoblasts; the MTT assay revealed an obvious increase of cell proliferation after transfection. The expression profiles of Six1, Myf5 and MyoD showed that their expression levels were significantly increased. These results together suggested that pEGFP-duSix1 vector was constructed successfully and overexpression of duck Six1 in the myoblasts could promote cell proliferation activity and significant up-regulate expression of Myf5 and MyoD.

Molecular cloning and in silico analysis of the duck (Anas platyrhynchos) MEF2A gene cDNA and its expression profile in muscle tissues during fetal development

The role of myogenic enhancer transcription factor 2a (MEF2A) in avian muscle during fetal development is unknown. In this work, we cloned the duck MEF2A cDNA sequence (GenBank accession no. HM460752) and examined its developmental expression profiles in cardiac muscle, non-vascular smooth muscle and skeletal muscle. Duck MEF2A cDNA comprised 1479 bp encoding 492 amino acid residues. In silico analysis showed that MEF2A contained MADS (MCM1, AGAMOUS, DEFICIENS and SRF -serum response factor), MEF2 and mitogen-activated protein kinase (MAPK) transcription domains with high homology to related proteins in other species. Modified sites in these domains were conserved among species and several variants were found. Quantitative PCR showed that MEF2A was expressed in all three muscles at each developmental stage examined, with the expression in smooth muscle being higher than in the other muscles. These results indicate that the conserved domains of duck MEF2A, including the MADS and MEF2 domains, are important for MEF2A transcription factor function. The expression of MEF2A in duck smooth muscle and cardiac muscle suggests that MEF2A plays a role in these two tissues.