Novel alternative splice variants of NFIX and their diverse mRNA expression patterns in dairy goat

•Two novel alternative splice variants of NFIX gene were detected in dairy goats.•Significant differences of mRNA expression of novel variants were revealed.•NFIXa showed higher mRNA expression level than NFIXb in several tissues (P < 0.05 or P < 0.01).

The nuclear factor I/X (NFIX) is a member of NFI family and contributes to muscle and brain development. Numerous genes coding for alternative splicing isoforms play potential but different roles in the biological process. To date, transcript variants of NFIX gene and their expression profiles have never been elucidated in dairy goat. Herein, we identified and verified the expression of two novel transcripts (NFIXa and NFIXb) of NFIX gene in dairy goat. Compared with the normal transcript (NFIX), the NFIXa variant lacked the first and ninth exons, while the NFIXb variant lacked the first, seventh and ninth exons; the NFIXa variant was 69 nt longer than the normal transcript in the 5′ end site of the seventh exon, while the NFIXb variant was 66 nt longer in the 5′ end site of the seventh exon. Quantitative real-time PCR results showed that the expression levels of the three variants were significantly different. The normal NFIX variant was abundantly expressed in the lungs, the NFIXa variant was highly expressed in the pancreas, and the NFIXb variant was abundantly expressed in both the lung and the pancreas. Additionally, the NFIXa variant showed a significantly higher expression level than those of the normal NFIX and the alternative NFIXb variants in the liver, spleen, adipose, intestine and the testis (P < 0.01 or P < 0.05), respectively. Expression of the NFIXa variant in the brain was significantly higher than that of the NFIXb variant (P < 0.01). These findings suggest that the NFIXa isoform is the most abundant isoform in certain tissues of the dairy goat. This study represents the first report on alternative splicing variants of the goat NFIX gene and their expression profiles. It should help elucidate the function of NFIX gene in dairy goat.