Long form PRLR (lPRLR) regulates genes involved in the triacylglycerol synthesis in goat mammary gland epithelial cells

Abstract

The prolactin receptor (PRLR) is a single-pass transmembrane receptor belonging to the class-1 cytokine receptor superfamily and known to play a crucial role in lactation and milk synthesis. However, very little information is available on the roles of PRLR in the regulation of lipid metabolism in the goat mammary gland. In this study, we cloned the whole cDNA of goat long form PRLR (lPRLR). The full-length cDNA of lPRLR was comprised of a 327-bp 5′-untranslated region, 1746-bp open reading frame and 183-bp 3′-UTR. The deduced amino acid sequence encoded 581 amino acids (aa) with signal peptide (24 aa) and single transmembrane domain (22 aa). Homology alignments revealed that the goat lPRLR was highly conserved among sheep, bovine, and buffalo. Real-time quantitative PCR suggested that goat lPRLR was predominantly expressed in the muscle and liver. Treatment of goat mammary epithelial cells (GMECs) with prolactin resulted in Protein Kinase B (AKT) phosphorylation, elevated Peroxisome Proliferator-Activated Receptor γ (PPARG), Sterol Regulatory Element-Binding Protein-1 (SREBP1), Fatty Acid Synthesis (FASN), and Acetyl-Coenzyme A Carboxylase Alpha (ACACA) mRNA levels, and significantly increased the triglyceride content (P<0.05). The decreases in expression observed after knockdown of PRLR relative to the control group averaged 76%, 55%, 52%, and 68% of PPARG, SREBP1, FASN and ACACA, respectively. These results possibly provide direct evidence that lPRLR is an extensive-distribution transmembrane protein, involved in regulating the triacylglycerol synthesis in GMECs during lactation.