Novel alternative splicing by exon skipping in KIT associated with whole-body roan in an intercrossed population of Landrace and Korean Native pigs

Abstract

The KIT locus has been suggested to be a strong candidate region linked with whole-body roan in the F-2 population produced by intercrosses between Landrace and Korean Native pigs. In this manuscript, we report the finding of a novel alternative splicing event in the porcine KIT gene that results in the skipping of exon 5 in the I-Rn allele. KIT mRNAs that lack exon 5 were identified in the large intestine and skin, suggesting that the mechanism responsible for the skipping of exon 5 may be tissue specific. A U-26 repeat in intron 5 showed complete linkage (LOD = 11.8) with the roan phenotype and absolute association with the black phenotype of the Korean Native pig (KNP) population samples, inferring that the repeat pattern may alter the complementary base-pairing-mediated looping-out of introns 4 and 5, which may mediate the exon 5-skipping event. Although the sample size in our study was relatively small, we speculate that the R3 allele containing the U-26 repeat is a causative element for the roan phenotype via alternative control of the exon skipping in our roan pedigree.