Exploration of dairy goat PITX2 alternative splice events and differential isoform expression

•Two novel alternative splicing transcripts of PITX2 gene were identified in dairy goats.•Significant differences of mRNA expression of novel variants were found.•PITX2-V2 expressed higher than PITX2 and PITX2-V1 in several tissues.

Paired-liked homodomain transcription factor 2 (PITX2), an important transcription factor, was vital in cell proliferation and differentiation, organogenesis (including pituitary development) and embryonic development. Alternative splicing events of PITX2 have been detected in zebrafish, Xenopus, chicken, mouse and humans, but not in goats. Herein, by cloning and sequencing, we firstly identified two novel isoforms (namely, PITX2-V1 and PITX2-V2) except the complete transcript PITX2 in dairy goat. The length of complete PITX2 coding sequence (CDS) was 978 base pair (bp), which had three exons. The CDS of PITX2-V1 was 830 bp, which was characterized with partial deletion of internal exon 3 of PITX2 gene. The length of PITX2-V2 CDS was 202 bp, which retained partial 5′ region of exon 1 and 3′ region of exon 3. The quantitative real − time polymerase chain reaction (qRT-PCR) analysis demonstrated that these three transcripts were widely and differently expressed among tissues. The relative expression levels of the three variants in brain, pancreas and testis were higher than other tissues. Different expression analysis suggested that the expression level of PITX2-V2 was significantly higher than PITX2 and PITX2-V1 in liver, lung, kidney, pancreas, adipose, and testis, but not in brain. These differences indicated that the expression of three variants were tissue-specific. This was the first finding on the splice variants of goat PITX2 gene and their mRNA expression patterns, which might provide a novel insight for further study on the function of PITX2 gene.