Abstract
Fatty Acid Elongase 7 (ELOVL7) is the newly discovered protein on human that catalyzes the rate-limiting step towards the synthesis of very long-chain fatty acids and exhibits the highest activity toward C18: 3 (n-3) acyl-CoAs, which is the precursor of eicosapentaenoic acid (EPA, 20: 5n-3). However, in ruminants, an overall understanding of ELOVLs gene family and the transcriptional regulation of ELOVL7 remain unknown. The purpose of this study is to investigate the transcriptional regulation and the influence of bovine ELOVL7 in bovine mammary epithelial cells (bMECs). Quantitative real-time PCR analysis demonstrated that ELOVLs gene family had differential expression patterns in bMECs, and bovine ELOVL7 was expressed in a tissue-specific manner, which was high in kidney, followed by in abdominal fat and in bMECs. Promoter analysis of bovine ELOVL7, including bioinformatics analyzes, dual-luciferase reporter assays, protein pull-down assay, Western blot assay, over-expression and RNA interference assay, have independently and synthetically demonstrated that transcription factor Sp1 (SP1) specifically interacted with the GC-box at -143 to -128 base pair on ELOVL7 promoter. Furthermore, the exogenous α-linolenic acid (ALA, 18: 3n-3), strengthened the binding of SP1 to the ELOVL7 proximal promoter, resulting in the accumulation of lipid droplets in bMECs. In conclusion, these data suggest that the transcription of bovine ELOVL7 is affected by the binding of SP1 and the treatment of ALA, moreover, enlightening us the profound role of SP1 in modulating lipid synthesis of the mammary gland in cattle.