ABSTRACT
AMPK is the key switch for providing the energy balance between cellular anabolic and catabolic processes. In this study, we aimed to screen the PRKAG1 (AMPKγ1) gene in high, moderate, and low producing Holstein dairy cows. A sample of 100 pregnant dairy cows, comprising 41 high, 33 moderate, and 26 low milk yields were selected from three large dairy herds in Isfahan province of Iran. Body condition score (BCS) was estimated before parturition while beta hydroxyl butyric acid (BHBA) as a measure of ketone bodies was measured at the fifth day postpartum. In addition, using three primer pairs covering exons 2-11 and 3'-UTR of the PRKAG1 gene, a random sample of 10 high milk yield dairy cows were amplified and sequenced. The sequencing results showed the presence of a T12571C mutation in intron 6 and a T14280C mutation in the 3'-untranslated region (UTR) of the PRKAG1 gene. Following a PCR reaction for amplification of the 3'-UTR amplicons, single strand conformation polymorphism (SSCP) assay was implemented for discrimination of the mutation in the studied population. Then, we evaluated if the mutation associates with the BCS, serum BHBA level, and production traits. The experimental analysis showed that the mutated allele significantly increased the BHBA level, BCS, as well as milk and protein yield. Bioinformatic study revealed that this 3'-UTR mutation distorts the target site of mir-423-5p microRNA which is one of the most highly expressed microRNAs in the bovine mammary gland, liver, and kidney. Given the role of AMPK in energy metabolism, the newly identified 3'-UTR mutation highlights the importance of AMPK and suggests a role of miRNAs for regulation of cellular metabolism, metabolism disorders, and production traits in Holstein dairy cows.
