Novel alternatively spliced isoforms of MEF2A and their mRNA expression patterns in pigs.

The present study aimed to identify the alternatively spliced isoforms of pig MEF2A gene and to determine theirmRNA expression patterns. Four alternatively spliced isoforms of pig MEF2A gene (i.e. MEF2A1, MEF2A2, MEF2A3 and MEF2A4) were cloned according to the results of transcriptome sequencing. The fifth to eighth exons of MEF2A1 were normally spliced. In MEF2A2, the fifth exon was missing; the sixth exon had an extra 138 bp at its 5' end, and the seventh exon had an extra 102 bp at its 3' end. In MEF2A3, the fifth exon was missing, and the sixth exon had an additional 138 bp at its 5' end. In MEF2A4, the seventh exon had an extra 102 bp at its 3' end. Quantitative real-time polymerase chain reaction (qPCR) analysis indicated that the expression profiles of the four alternatively spliced transcripts in the longissimus dorsi differed between the Mashen and Large White pigs. MEF2A1 and MEF2A2 expression levels were the highest at 90 days of age and lowest at 180 days of age. MEF2A3 and MEF2A4 expression levels increased with age (in days). The four alternatively spliced isoforms of MEF2A were also expressed in the small intestine, cerebellum, pancreas, heart and lung. The discovery of new alternatively spliced transcripts of the MEF2A gene may be utilized in understanding its biological functions.