ELOVL6 promoter binding sites directly targeted by sterol regulatory element binding protein 1 in fatty acid synthesis of goat mammary epithelial cells

Abstract

The elongation of long-chain fatty acid family member 6 (ELOVL6) gene plays an important role in the synthesis of long-chain saturated and monounsaturated fatty acids. Although some studies have revealed that ELOVL6 is the target of sterol regulatory element binding protein 1 (SREBP1; gene name SREBF1) in rodents, the mechanism underlying ELOVL6 regulation during lactation in dairy goats remains unknown. The present study aimed to investigate the transcriptional regulation mechanism of ELOVL6 in goat mammary epithelial cells (GMEC). We used PCR to clone and sequenced a 2,370 bp fragment of the ELOVL6 5′ flanking region from goat genomic DNA. Deletion analysis revealed a core promoter region located −105 to −40 bp upstream of the transcriptional start site. Mutant sterol regulatory elements (SRE) 1 and 3 significantly reduced the ELOVL6 promoter activities in GMEC. Both SRE1 and SRE3 binding sites were required for the basal transcriptional activity of ELOVL6. Luciferase reporter assays showed that SREBF1 knockdown decreased ELOVL6 promoter activities in GMEC. Furthermore, SRE1 and SRE3 sites were simultaneously mutated completely abolished the stimulatory effect of SREBF1 and the repressive effect of linoleic acid on ELOVL6 gene promoter activities. Furthermore, chromatin immunoprecipitation assays confirmed that SREBP1 directly bound to SRE sites in the ELOVL6 promoter. In conclusion, these results indicate that SREBP1 regulates ELOVL6 transcription via the SRE elements located in the ELOVL6 promoter in goat mammary gland.

Mutation of Signal Transducer and Activator of Transcription 5 (STAT5) Binding Sites Decreases Milk Allergen αS1-Casein Content in Goat Mammary Epithelial Cells

“…In this case, prolactin could also not activate its transcriptional activity, indicating that these two sites were the main binding sites of STAT5 in the CSN1S1 promoter. Compared with the site mutation analysis, the ChIP assay is the direct evidence to confirm the binding of transcription factors to the promoter region [40,42]. In the present study, ChIP assays showed that STAT5 could directly bind to GAS1 and GAS2 sites and promote the transcription of the CSN1S1 gene.…”

“…In order to determine the core promoter region of the CSN1S1 gene in dairy goats, we performed a segment-by-step deletion analysis starting from −2018 bp upstream of transcription start site [41]. When the CSN1S1 promoter fragment was deleted from −110 to −18 bp, the promoter activity decreased by 89%; therefore, −110~−18 bp upstream of transcription start site was identified as the active center of the goat CSN1S1 promoter [42]. The core promoter region contains two STAT5 binding sites (GAS1 and GAS2), thus we hypothesized that STAT5 may have a great effect on the transcriptional activity of the CSN1S1 gene.…”

Effects of the epidermal growth factor receptor inhibitor, gefitinib, on lipid and hyaluronic acid synthesis in cultured HaCaT keratinocytes

“…The data are representatives of at least three independent experiments activates both the pathways. 33 The expression of ACCα, FASN, ELOVL5 and ELOVL6 is regulated by SREBP-1a or SREBP-1c, [34][35][36] while the expression of HMGCR is known to be regulated by SREBP-2. 37 However, the enzymes involved in ceramide synthesis are not regulated by SREBPs; conversely, SREBPs are regulated by ceramide synthesis.…”

The LXRB-SREBP1 network regulates lipogenic homeostasis by controlling the synthesis of polyunsaturated fatty acids in goat mammary epithelial cells

“…It is evident that sterol regulatory element binding transcription factor 1 (SREBP1) and liver X receptor (LXR) play a crucial role in regulating the expression of SCD1 [ 10 , 11 ]. Although some evidence suggests that ELOVL promoters are targets of SREBP1 in rodents [ 12 , 13 ] and goat [ 14 ], knowledge of how the synthesis of PUFA is regulated in the ruminant mammary gland is unclear.…”

“…Data in rodents underscored an important role for SREBP1 in altering elongation of long chain fatty acids [ 18 , 19 ]. For instance, in mouse [ 12 ] and goats [ 14 ], ELOVL6 is suggested to be a target of SREBP1 because its promoter contains SREBP1 response element (SRE). Besides SREBP1, at least in non-ruminants, the transcription factor liver X receptor (LXR) is also involved in lipogenesis in an SREBP-dependent and -independent manner [ 20 ].…”