| Summary: | Long-chain acyl-CoA synthetase 1 (ACSL1) plays an important role in fatty acid metabolism and fat deposition. The transcription of the <i>ACSL1</i> gene is regulated specifically among cells and physiological processes, and transcriptional regulation of <i>ACSL1</i> in adipogenesis remains elusive. Here, we characterize transcription factors (TFs) associated with adipogenesis in the porcine <i>ACSL1</i> gene. CCAAT-enhancer binding protein (C/EBP)α, a well-known adipogenic marker, was found to enhance the expression of the <i>ACSL1</i> gene via binding two tandem motifs in the promoter. Further, we demonstrate that ACSL1 mediates C/EBPα effects on adipogenesis in preadipocytes cultured from subcutaneous fat tissue of pigs via gain- and loss-of-function analyses. The cAMP-response element binding protein, another TF involved in adipogenesis, was also identified in the regulation of <i>ACSL1</i> gene expression. Additionally, single nucleotide polymorphisms (SNPs) were screened in the promoter of <i>ACSL1</i> among four breeds including the Chinese indigenous Min, and Duroc, Berkshire, and Yorkshire pigs through sequencing of PCR products. Two tightly linked SNPs, −517G>T and −311T>G, were found exclusively in Min pigs. The haplotype mutation decreases promoter activity in PK-15 and ST cells, and in vivo the expression of <i>ACSL1</i>, illustrating a possible role in adipogenesis regulated by C/EBPα/ACSL1 axis. Additionally, a total of 24 alternative splicing transcripts were identified, indicating the complexity of alternative splicing in the <i>ACSL1</i> gene. The results will contribute to further revealing the regulatory mechanisms of <i>ACSL1</i> during adipogenesis and to the characterization of molecular markers for selection of fat deposition in pigs.
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