Transcriptional Regulation of the Bovine Fatty Acid Transport Protein 1 Gene by Krüppel-Like Factors 15.

Abstract

Simple SummaryThe nutritional value and qualities of beef are enhanced when the unsaturated fatty acid content is increased. Fatty acid transport protein 1 (FATP1), also called SLC27A1, an integral membrane protein that facilitates long-chain fatty acid influx, is involved in the genetic network for oleic acid synthesis in beef. Polymorphisms in bovine SLC27A1 gene are most significantly associated with oleic acid. Its expression exhibits significant positive correlations with bovine intramuscular fat content in the longissimus thoracis muscle. However, the transcription factors that contribute to the control and regulation of its expression have not been characterized extensively. In this study, we determined the tissue distribution of SLC27A1 mRNA and found that bovine SLC27A1 was highly expressed in subcutaneous adipose tissue and the longissimus thoracis muscle. Furthermore, we analyzed the molecular mechanisms involved in SLC27A1 regulation and found that the transcriptional activity of SLC27A1 gene was dependent on KLF15 transcription factor. These results may lead to an enhanced understanding of the regulation of SLC27A1 expression in other models, as well as provide new insights into the regulatory mechanism and biological functions of the SLC27A1 gene in determining the lipid composition in beef.Oleic acid is a major monounsaturated fatty acid, which accounts for about 33% of the fatty acid content in beef and is considered to have the least negative effect on serum cholesterol levels. Fatty acid transport protein 1 (FATP1), an integral membrane protein that facilitates long-chain fatty acid (LCFA) influx, is involved in the genetic network for oleic acid synthesis in beef. Its expression exhibits significant positive correlations with intramuscular fat (IMF) content in the longissimus thoracis. However, the expression mechanism of SLC27A1 or FATP1 is still unclear. To elucidate the molecular mechanisms involved in bovine SLC27A1 regulation, we cloned and characterized the promoter region of SLC27A1. By applying 5′-rapid amplification of cDNA end analysis, we identified two alternative splice variants of this gene. Using a series of 5′ deletion promoter plasmids in luciferase reporter assays, we found that the core promoter was 96 base pairs upstream from the transcription initiation site. Electrophoretic mobility shift assay combined with a site-directed mutation experiment demonstrated that KLF15 binding to the promoter region drives the SLC27A1 transcription. KLF15 plays an essential role in adipogenesis and skeletal muscle lipid flux. Thus, these results might provide further information on the regulatory roles of SLC27A1 gene in mediating the lipid composition in beef.