5'-flanking variants of equine casein genes (CSN1S1, CSN1S2, CSN2, CSN3) and their relationship with gene expression and milk composition.
Jakub Cieslak, Lukasz Wodas, Alicja Borowska, Piotr Pawlak, Grazyna Czyzak-Runowska, Jacek Wojtowski, Kamila Puppel, Beata Kuczynska, Mariusz Mackowski
Author Information
Jakub Cieslak: Department of Horse Breeding, Poznan University of Life Sciences, Wolynska 33, 60-637, Poznan, Poland. jcieslak@up.poznan.pl. ORCID
Lukasz Wodas: Department of Horse Breeding, Poznan University of Life Sciences, Wolynska 33, 60-637, Poznan, Poland.
Alicja Borowska: Department of Horse Breeding, Poznan University of Life Sciences, Wolynska 33, 60-637, Poznan, Poland.
Piotr Pawlak: Department of Genetics and Animal Breeding, Poznan University of Life Sciences, Wolynska 33, 60-637, Poznan, Poland.
Grazyna Czyzak-Runowska: Department of Animal Breeding and Product QualityAssessment, Poznan University of Life Sciences, Sloneczna 1, 62-002, Zlotniki, Poland.
Jacek Wojtowski: Department of Animal Breeding and Product QualityAssessment, Poznan University of Life Sciences, Sloneczna 1, 62-002, Zlotniki, Poland.
Kamila Puppel: Department of Animal Science, Cattle Breeding Division, Warsaw University of Life Sciences, Ciszewskiego 8, 02-786, Warsaw, Poland.
Beata Kuczynska: Department of Animal Science, Cattle Breeding Division, Warsaw University of Life Sciences, Ciszewskiego 8, 02-786, Warsaw, Poland.
Mariusz Mackowski: Department of Horse Breeding, Poznan University of Life Sciences, Wolynska 33, 60-637, Poznan, Poland.
Genes encoding casein proteins are important candidates for milk composition traits in mammals. In the case of the domestic horse, our knowledge of casein genes is limited mainly to coding sequence variants. This study involved screening for polymorphism in 5'-flanking regions of four genes encoding equine caseins (CSN1S1, CSN1S2, CSN2, and CSN3) and making a preliminary assessment of their effect on the gene expression (on the mRNA and protein levels) and milk composition traits in selected horse breeds. Altogether, 23 polymorphisms (21 described previously SNPs and two novel InDels) were found in the studied sequences, the majority of which are common in various horse breeds. Statistical analysis revealed that some are putatively associated with gene expression or milk composition - for example, the c.-2047_-2048insAT polymorphism (CSN1S1) turns out to be related to the total milk protein content in Polish Primitive Horse (p < 0.05), whereas c.-2105C>G SNP (CSN2) is related to beta-casein relative mRNA level and milk lactose concentration in the Polish Coldblood Horse breed (p < 0.05). We have also found significant effects of horse breed and lactation time-point on gene expression and mare's milk composition. Our study indicates that the 5'-regulatory regions of genes encoding casein proteins are interesting targets for functional studies of their expression and the composition traits of mare's milk.
