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Zhang W, Zhang C, Luo J, Xu H, Liu J, Loor JJ, Shi H. The LXRB-SREBP1 network regulates lipogenic homeostasis by controlling the synthesis of polyunsaturated fatty acids in goat mammary epithelial cells. J Anim Sci Biotechnol 2022; 13:120. [PMID: 36336695 PMCID: PMC9639257 DOI: 10.1186/s40104-022-00774-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 09/05/2022] [Indexed: 11/09/2022] Open
Abstract
Background In rodents, research has revealed a role of liver X receptors (LXR) in controlling lipid homeostasis and regulating the synthesis of polyunsaturated fatty acids (PUFA). Recent data suggest that LXRB is the predominant LXR subtype in ruminant mammary cells, but its role in lipid metabolism is unknown. It was hypothesized that LXRB plays a role in lipid homeostasis via altering the synthesis of PUFA in the ruminant mammary gland. We used overexpression and knockdown of LXRB in goat primary mammary epithelial cells (GMEC) to evaluate abundance of lipogenic enzymes, fatty acid profiles, content of lipid stores and activity of the stearoyl-CoA desaturase (SCD1) promoter. Results Overexpression of LXRB markedly upregulated the protein abundance of LXRB while incubation with siRNA targeting LXRB markedly decreased abundance of LXRB protein. Overexpression of LXRB plus T0901317 (T09, a ligand for LXR) dramatically upregulated SCD1 and elongation of very long chain fatty acid-like fatty acid elongases 5–7 (ELOVL 5–7), which are related to PUFA synthesis. Compared with the control, cells overexpressing LXRB and stimulated with T09 had greater concentrations of C16:0, 16:1, 18:1n7,18:1n9 and C18:2 as well as desaturation and elongation indices of C16:0. Furthermore, LXRB-overexpressing cells incubated with T09 had greater levels of triacylglycerol and cholesterol. Knockdown of LXRB in cells incubated with T09 led to downregulation of genes encoding elongases and desaturases. Knockdown of LXRB attenuated the increase in triacylglycerol and cholesterol that was induced by T09. In cells treated with dimethylsulfoxide, knockdown of LXRB increased the concentration of C16:0 at the expense of C18:0, while a significant decrease in C18:2 was observed in cells incubated with both siLXRB and T09. The abundance of sterol regulatory element binding transcription factor 1 precursor (pSREBP1) and its mature fragment (nSREBP1) was upregulated by T09, but not LXRB overexpression. In the cells cultured with T09, knockdown of LXRB downregulated the abundance for pSREBP1 and nSREBP1. Luciferase reporter assays revealed that the activities of wild type SCD1 promoter or fragment with SREBP1 response element (SRE) mutation were decreased markedly when LXRB was knocked down. Activity of the SCD1 promoter that was induced by T09 was blocked when the SRE mutation was introduced. Conclusion The current study provides evidence of a physiological link between the LXRB and SREBP1 in the ruminant mammary cell. An important role was revealed for the LXRB-SREBP1 network in the synthesis of PUFA via the regulation of genes encoding elongases and desaturases. Thus, targeting this network might elicit broad effects on lipid homeostasis in ruminant mammary gland. Supplementary Information The online version contains supplementary material available at 10.1186/s40104-022-00774-4.
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Affiliation(s)
- Wenying Zhang
- grid.13402.340000 0004 1759 700XInstitute of Dairy Science, College of Animal Sciences, Zhejiang University, Hangzhou, 310058 China
| | - Changhui Zhang
- grid.144022.10000 0004 1760 4150College of Animal Science and Technology, Northwest A&F University, Yangling, 712100 China
| | - Jun Luo
- grid.144022.10000 0004 1760 4150College of Animal Science and Technology, Northwest A&F University, Yangling, 712100 China
| | - Huifen Xu
- grid.108266.b0000 0004 1803 0494College of Animal Science and Technology, Henan Agricultural University, Zhengzhou, 450046 China ,grid.419897.a0000 0004 0369 313XKey Laboratory of Molecular Animal Nutrition (Zhejiang University), Ministry of Education, Hangzhou, 310058, China
| | - Jianxin Liu
- grid.13402.340000 0004 1759 700XInstitute of Dairy Science, College of Animal Sciences, Zhejiang University, Hangzhou, 310058 China
| | - Juan J. Loor
- grid.35403.310000 0004 1936 9991Mammalian Nutrition Physiology Genomics, Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, IL 61801 USA
| | - Hengbo Shi
- grid.13402.340000 0004 1759 700XInstitute of Dairy Science, College of Animal Sciences, Zhejiang University, Hangzhou, 310058 China ,grid.419897.a0000 0004 0369 313XKey Laboratory of Molecular Animal Nutrition (Zhejiang University), Ministry of Education, Hangzhou, 310058, China
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2
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Malek M, Wawrzyniak AM, Koch P, Lüchtenborg C, Hessenberger M, Sachsenheimer T, Jang W, Brügger B, Haucke V. Inositol triphosphate-triggered calcium release blocks lipid exchange at endoplasmic reticulum-Golgi contact sites. Nat Commun 2021; 12:2673. [PMID: 33976123 PMCID: PMC8113574 DOI: 10.1038/s41467-021-22882-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 04/02/2021] [Indexed: 02/03/2023] Open
Abstract
Vesicular traffic and membrane contact sites between organelles enable the exchange of proteins, lipids, and metabolites. Recruitment of tethers to contact sites between the endoplasmic reticulum (ER) and the plasma membrane is often triggered by calcium. Here we reveal a function for calcium in the repression of cholesterol export at membrane contact sites between the ER and the Golgi complex. We show that calcium efflux from ER stores induced by inositol-triphosphate [IP3] accumulation upon loss of the inositol 5-phosphatase INPP5A or receptor signaling triggers depletion of cholesterol and associated Gb3 from the cell surface, resulting in a blockade of clathrin-independent endocytosis (CIE) of Shiga toxin. This phenotype is caused by the calcium-induced dissociation of oxysterol binding protein (OSBP) from the Golgi complex and from VAP-containing membrane contact sites. Our findings reveal a crucial function for INPP5A-mediated IP3 hydrolysis in the control of lipid exchange at membrane contact sites.
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Affiliation(s)
- Mouhannad Malek
- grid.418832.40000 0001 0610 524XLeibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Anna M. Wawrzyniak
- grid.418832.40000 0001 0610 524XLeibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Peter Koch
- grid.418832.40000 0001 0610 524XLeibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Christian Lüchtenborg
- grid.7700.00000 0001 2190 4373Heidelberg University Biochemistry Center (BZH), Heidelberg University, Heidelberg, Germany
| | - Manuel Hessenberger
- grid.418832.40000 0001 0610 524XLeibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Timo Sachsenheimer
- grid.7700.00000 0001 2190 4373Heidelberg University Biochemistry Center (BZH), Heidelberg University, Heidelberg, Germany
| | - Wonyul Jang
- grid.418832.40000 0001 0610 524XLeibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Britta Brügger
- grid.7700.00000 0001 2190 4373Heidelberg University Biochemistry Center (BZH), Heidelberg University, Heidelberg, Germany
| | - Volker Haucke
- grid.418832.40000 0001 0610 524XLeibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany ,grid.14095.390000 0000 9116 4836Faculty of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Berlin, Germany
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3
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He Q, Luo J, Wu J, Li Z, Yao W, Zang S, Niu H. ELOVL6 promoter binding sites directly targeted by sterol regulatory element binding protein 1 in fatty acid synthesis of goat mammary epithelial cells. J Dairy Sci 2021; 104:6253-6266. [PMID: 33685712 DOI: 10.3168/jds.2020-19292] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 01/07/2021] [Indexed: 11/19/2022]
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.
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Affiliation(s)
- Qiuya He
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, PR China
| | - Jun Luo
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
| | - Jiao Wu
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, PR China
| | - Zhuang Li
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, PR China
| | - Weiwei Yao
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, PR China
| | - Saige Zang
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, PR China
| | - Huimin Niu
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, PR China
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4
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Grinman DY, Careaga VP, Wellberg EA, Dansey MV, Kordon EC, Anderson SM, Maier MS, Burton G, MacLean PS, Rudolph MC, Pecci A. Liver X receptor-α activation enhances cholesterol secretion in lactating mammary epithelium. Am J Physiol Endocrinol Metab 2019; 316:E1136-E1145. [PMID: 30964702 PMCID: PMC6620573 DOI: 10.1152/ajpendo.00548.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 04/01/2019] [Accepted: 04/04/2019] [Indexed: 11/22/2022]
Abstract
Liver X receptors (LXRs) are ligand-dependent transcription factors activated by cholesterol metabolites. These receptors induce a suite of target genes required for de novo synthesis of triglycerides and cholesterol transport in many tissues. Two different isoforms, LXRα and LXRβ, have been well characterized in liver, adipocytes, macrophages, and intestinal epithelium among others, but their contribution to cholesterol and fatty acid efflux in the lactating mammary epithelium is poorly understood. We hypothesize that LXR regulates lipogenesis during milk fat production in lactation. Global mRNA analysis of mouse mammary epithelial cells (MECs) revealed multiple LXR/RXR targets upregulated sharply early in lactation compared with midpregnancy. LXRα is the primary isoform, and its protein levels increase throughout lactation in MECs. The LXR agonist GW3965 markedly induced several genes involved in cholesterol transport and lipogenesis and enhanced cytoplasmic lipid droplet accumulation in the HC11 MEC cell line. Importantly, in vivo pharmacological activation of LXR increased the milk cholesterol percentage and induced sterol regulatory element-binding protein 1c (Srebp1c) and ATP-binding cassette transporter a7 (Abca7) expression in MECs. Cumulatively, our findings identify LXRα as an important regulator of cholesterol incorporation into the milk through key nodes of de novo lipogenesis, suggesting a potential therapeutic target in women with difficulty initiating lactation.
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Affiliation(s)
- Diego Y Grinman
- Instituto de Fisiología, Biología Molecular y Neurociencias, CONICET, Universidad de Buenos Aires , Buenos Aires , Argentina
| | - Valeria P Careaga
- Unidad De Microanálisis Y Métodos Físicos Aplicados a la Química Orgánica, CONICET, Universidad de Buenos Aires , Buenos Aires , Argentina
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires, Buenos Aires , Argentina
| | - Elizabeth A Wellberg
- Department of Pathology, University of Colorado, Anschutz Medical Campus, Denver, Colorado
| | - María V Dansey
- Unidad De Microanálisis Y Métodos Físicos Aplicados a la Química Orgánica, CONICET, Universidad de Buenos Aires , Buenos Aires , Argentina
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires , Buenos Aires , Argentina
| | - Edith C Kordon
- Instituto de Fisiología, Biología Molecular y Neurociencias, CONICET, Universidad de Buenos Aires , Buenos Aires , Argentina
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires , Buenos Aires , Argentina
| | - Steven M Anderson
- Department of Pathology, University of Colorado, Anschutz Medical Campus, Denver, Colorado
| | - Marta S Maier
- Unidad De Microanálisis Y Métodos Físicos Aplicados a la Química Orgánica, CONICET, Universidad de Buenos Aires , Buenos Aires , Argentina
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires, Buenos Aires , Argentina
| | - Gerardo Burton
- Unidad De Microanálisis Y Métodos Físicos Aplicados a la Química Orgánica, CONICET, Universidad de Buenos Aires , Buenos Aires , Argentina
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires, Buenos Aires , Argentina
| | - Paul S MacLean
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado, Anschutz Medical Campus, Denver, Colorado
| | - Michael C Rudolph
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado, Anschutz Medical Campus, Denver, Colorado
| | - Adali Pecci
- Instituto de Fisiología, Biología Molecular y Neurociencias, CONICET, Universidad de Buenos Aires , Buenos Aires , Argentina
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires , Buenos Aires , Argentina
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5
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Xu HF, Luo J, Zhang XY, Li J, Bionaz M. Activation of liver X receptor promotes fatty acid synthesis in goat mammary epithelial cells via modulation of SREBP1 expression. J Dairy Sci 2019; 102:3544-3555. [PMID: 30738675 DOI: 10.3168/jds.2018-15538] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 12/12/2018] [Indexed: 01/04/2023]
Abstract
In bovine mammary tissue and cells, liver X receptor (LXR) regulates lipid synthesis mainly via transactivation of the transcription factor sterol regulatory element binding protein 1 (SREBP1). In the present work, we investigated the role of LXR in controlling lipid synthesis via transactivation of SREBP1 in goat primary mammary cells (GMEC). The GMEC were treated with a synthetic agonist of LXR, T0901317, and transactivation and transcription of SREBP1, expression of lipogenic genes, and fatty acid profiling and triacylglycerol (TAG) content of the cells were measured. A mild increase in the mRNA expression level of LXRα (NR1H3) was observed following treatment with different concentrations of T0901317, and a dose-dependent increase in mRNA and transactivation of SREBP1 was detected. Activation of LXR resulted in a significant increase in the mRNA expression of most of the measured genes related to de novo synthesis, desaturation, and transport of fatty acids; TAG synthesis; and transcription regulators. Compared with the control, total content of cellular TAG increased by more than 20% with T0901317 treatment. Furthermore, addition of T0901317 increased the proportion of unsaturated fatty acids (e.g., C16:1, C18:1, C20:1, and C22:1), and decreased the proportion of saturated fatty acids (e.g., C16:0, C18:0, C20:0, and C22:0). These results provide evidence that LXR regulates the expression and activity of SREBP1. Our results indicated that LXR participate in regulating the transcription of genes involved in milk fat synthesis in GMEC in an SREBP1-dependent fashion.
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Affiliation(s)
- H F Xu
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, 450046, P. R. China
| | - J Luo
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, P. R. China.
| | - X Y Zhang
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, P. R. China
| | - J Li
- College of Animal Science and Technology, Henan University of Animal Husbandry and Economy, Zhengzhou, Henan, 450046, P. R. China
| | - M Bionaz
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis 97331.
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6
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Xu H, Luo J, Tian H, Li J, Zhang X, Chen Z, Li M, Loor JJ. Rapid communication: lipid metabolic gene expression and triacylglycerol accumulation in goat mammary epithelial cells are decreased by inhibition of SREBP-1. J Anim Sci 2018; 96:2399-2407. [PMID: 29846631 DOI: 10.1093/jas/sky069] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 05/23/2018] [Indexed: 12/21/2022] Open
Abstract
In mammals, sterol regulatory element binding protein-1 (SREBP-1) is the master regulator of fatty acid and triacylglycerol synthesis. Recent gene silencing studies in mammary cells indicate that SREBP-1 has a central role in milk fat synthesis. However, SREBP-1 knockdown studies in goat mammary cells have not been performed; hence, its direct role in controlling mRNA expression of lipid metabolism genes and triacylglycerol synthesis remains unknown. Inhibition of SREBP-1 in goat mammary epithelial cells (GMEC) by small interference RNA (siRNA) markedly reduced the content of cellular triacylglycerol (~50% decrease, P < 0.05) and was partly related to downregulation of AGPAT6, LPIN1, and DGAT2 (-23%, -28% and -19%, respectively. P < 0.05), which are key enzymes involved in triacylglycerol synthesis, cellular triacylglycerol content and lipid droplet accumulation all decreased by SREBP-1 inhibition. The expression of lipid droplet formation and secretion genes was not altered in response to treatment. Although the lack of effect on expression of ACACA and FASN (rate-limiting enzymes for de novo fatty acid synthesis) with SREBP-1 knockdown was unexpected (P > 0.05), the downregulation of genes related to synthesis of acetyl-CoA and acetate activation (ACLY, ACSS2, and IDH1, P < 0.05) suggests that lipogenesis was inhibited. SREBP-1 knockdown also resulted in decreased expression of genes associated with fatty acid desaturation and elongation (SCD1 and ELOVL6, P < 0.05), long-chain fatty acid (LCFA) activation and transport (ACSL1, FABP3, and SLC27A6, P < 0.05). The results underscored the essential role of SREBP-1 not only in fatty acid synthesis but also in desaturation, elongation, and esterification in GMEC. Clearly, the lack of effect on ACACA and FASN, both of which are considered the key lipogenic enzymes, implies that there may be different regulatory mechanisms in goat compared with bovine mammary cells.
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Affiliation(s)
- Huifen Xu
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, P. R. China.,College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, P.R. China
| | - Jun Luo
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, P. R. China
| | - Huibin Tian
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, P. R. China
| | - Jun Li
- College of Animal Science and Technology, Henan University of Animal Husbandry and Economy, Zhengzhou, Henan, P.R. China
| | - Xueying Zhang
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, P. R. China
| | - Zhi Chen
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, P. R. China
| | - Ming Li
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, P.R. China
| | - Juan J Loor
- Mammalian NutriPhysioGenomics, Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, IL
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7
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Osorio JS, Vailati-Riboni M, Palladino A, Luo J, Loor JJ. Application of nutrigenomics in small ruminants: Lactation, growth, and beyond. Small Rumin Res 2017. [DOI: 10.1016/j.smallrumres.2017.06.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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8
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Shi H, Zhang C, Xu Z, Xu X, Lv Z, Luo J, Loor J. Nuclear receptor subfamily 1 group H member 2 (LXRB) is the predominant liver X receptor subtype regulating transcription of 2 major lipogenic genes in goat primary mammary epithelial cells. J Dairy Sci 2017. [DOI: 10.3168/jds.2016-12510] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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9
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Yao DW, Luo J, He QY, Li J, Wang H, Shi HB, Xu HF, Wang M, Loor JJ. Characterization of the liver X receptor-dependent regulatory mechanism of goat stearoyl-coenzyme A desaturase 1 gene by linoleic acid. J Dairy Sci 2017; 99:3945-3957. [PMID: 26947306 DOI: 10.3168/jds.2015-10601] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 01/13/2016] [Indexed: 01/05/2023]
Abstract
Stearoyl-coenzyme A desaturase 1 (SCD1) is a key enzyme in the biosynthesis of palmitoleic and oleic acid. Although the transcriptional regulatory mechanism of SCD1 via polyunsaturated fatty acids (PUFA) has been extensively explored in nonruminants, the existence of such mechanism in ruminant mammary gland remains unknown. In this study, we used goat genomic DNA to clone and sequence a 1,713-bp fragment of the SCD1 5' flanking region. Deletion assays revealed a core region of the promoter located between -415 and -109 bp upstream of the transcription start site, and contained the highly conserved PUFA response region. An intact PUFA response region was required for the basal transcriptional activity of SCD1. Linoleic acid reduced endogenous expression of SCD1 and sterol regulatory element binding factor-1 (SREBF1) in goat mammary epithelial cells. Further analysis indicated that both the sterol response element (SRE) and the nuclear factor Y (NF-Y) binding site in the SCD1 promoter were responsible for the inhibition effect by linoleic acid, whereas the effect was abrogated once NF-Y was deleted. In addition, SRE and NF-Y were partly responsible for the transcriptional activation induced via the liver X receptor agonist T 4506585 (Sigma-Aldrich, St. Louis, MO). When goat mammary epithelial cells were cultured with linoleic acid, addition of T 4506585 markedly increased SCD1 transcription in controls, but had no effect on cells with a deleted SRE promoter. These results demonstrated that linoleic acid can regulate SCD1 expression at the transcriptional level through SRE and NF-Y in a liver X receptor-dependent fashion in the goat mammary gland.
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Affiliation(s)
- D W Yao
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, P. R. China 712100
| | - J Luo
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, P. R. China 712100.
| | - Q Y He
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, P. R. China 712100
| | - J Li
- College of Animal Science and Technology, Henan University of Animal Husbandry and Economy, Zhengzhou, Henan, P. R. China 450046
| | - H Wang
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, P. R. China 712100
| | - H B Shi
- College of Animal Sciences, Zhejiang Sci-Tech University, Hangzhou, P. R. China 310058
| | - H F Xu
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, P. R. China 712100
| | - M Wang
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, P. R. China 712100
| | - J J Loor
- Mammalian NutriPhysioGenomics, Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana 61801.
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10
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Yao DW, Luo J, He QY, Xu HF, Li J, Shi HB, Wang H, Chen Z, Loor JJ. Liver X receptor α promotes the synthesis of monounsaturated fatty acids in goat mammary epithelial cells via the control of stearoyl-coenzyme A desaturase 1 in an SREBP-1-dependent manner. J Dairy Sci 2016; 99:6391-6402. [PMID: 27209141 DOI: 10.3168/jds.2016-10990] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 03/31/2016] [Indexed: 12/30/2022]
Abstract
Stearoyl-coenzyme A desaturase 1 (SCD1) is a pivotal enzyme in the biosynthesis of monounsaturated fatty acids (MUFA). It is tightly regulated by transcription factors that control lipogenesis. In nonruminants, liver X receptor α (LXRα) is a nuclear receptor and transcription factor that acts as a key sensor of cholesterol and lipid homeostasis. However, the mechanism whereby LXRα regulates the expression and transcriptional activity of SCD1 in ruminant mammary cells remains unknown. In this study with goat mammary epithelial cells (GMEC), the LXRα agonist T 4506585 (T09) markedly enhanced the mRNA expression of SCD1 and sterol regulatory element binding factor 1 (SREBF1). The concentrations of C16:1 and C18:1 and their desaturation indices also were increased by LXRα activation. However, knockdown of LXRα did not alter the mRNA expression of SCD1. Although SCD1 was repressed by SREBF1 knockdown, T09 significantly increased SCD1 expression. Further analysis revealed that the SCD1 promoter activity was activated by LXRα overexpression. The goat SCD1 promoter contains 2 LXR response elements (LXRE), 1 sterol response element (SRE), and 1 nuclear factor Y (NF-Y) binding site. Site-directed mutagenesis of LXRE1, LXRE2, or SRE alone did not eliminate the upregulation of SCD1 when LXRα was overexpressed. In contrast, when NF-Y alone or in combination with SRE was mutated simultaneously, the basal transcriptional activity of the SCD1 promoter was markedly decreased and did not respond to LXRα overexpression. Furthermore, when SREBF1 was knocked down, overexpression of LXRα did not affect the promoter activity of SCD1. Together, these data suggest that LXRα regulates the expression of SCD1 through increasing SREBP-1 abundance to promote interaction with SRE and NF-Y binding sites. The present study provides evidence that LXRα is involved in the synthesis of MUFA in the goat mammary gland through an indirect mechanism.
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Affiliation(s)
- D W Yao
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, P. R. China
| | - J Luo
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, P. R. China.
| | - Q Y He
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, P. R. China
| | - H F Xu
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, P. R. China
| | - J Li
- College of Animal Science and Technology, Henan University of Animal Husbandry and Economy, Zhengzhou, Henan, P. R. China 450046
| | - H B Shi
- College of Animal Sciences, Zhejiang Sci-Tech University, Hangzhou, P. R. China 310058
| | - H Wang
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, P. R. China
| | - Z Chen
- Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, P. R. China
| | - J J Loor
- Mammalian NutriPhysioGenomics, Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana 61801.
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11
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Osorio JS, Lohakare J, Bionaz M. Biosynthesis of milk fat, protein, and lactose: roles of transcriptional and posttranscriptional regulation. Physiol Genomics 2016; 48:231-56. [DOI: 10.1152/physiolgenomics.00016.2015] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The demand for high-quality milk is increasing worldwide. The efficiency of milk synthesis can be improved by taking advantage of the accumulated knowledge of the transcriptional and posttranscriptional regulation of genes coding for proteins involved in the synthesis of fat, protein, and lactose in the mammary gland. Research in this area is relatively new, but data accumulated in the last 10 years provide a relatively clear picture. Milk fat synthesis appears to be regulated, at least in bovines, by an interactive network between SREBP1, PPARγ, and LXRα, with a potential role for other transcription factors, such as Spot14, ChREBP, and Sp1. Milk protein synthesis is highly regulated by insulin, amino acids, and amino acid transporters via transcriptional and posttranscriptional routes, with the insulin-mTOR pathway playing a central role. The transcriptional regulation of lactose synthesis is still poorly understood, but it is clear that glucose transporters play an important role. They can also cooperatively interact with amino acid transporters and the mTOR pathway. Recent data indicate the possibility of nutrigenomic interventions to increase milk fat synthesis by feeding long-chain fatty acids and milk protein synthesis by feeding amino acids. We propose a transcriptional network model to account for all available findings. This model encompasses a complex network of proteins that control milk synthesis with a cross talk between milk fat, protein, and lactose regulation, with mTOR functioning as a central hub.
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Affiliation(s)
| | - Jayant Lohakare
- Oregon State University, Corvallis, Oregon; and
- Kangwon National University, Chuncheon, South Korea
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12
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Xu H, Luo J, Wang H, Wang H, Zhang T, Tian H, Yao D, Loor J. Sterol regulatory element binding protein-1 (SREBP-1)c promoter: Characterization and transcriptional regulation by mature SREBP-1 and liver X receptor α in goat mammary epithelial cells. J Dairy Sci 2016; 99:1595-1604. [DOI: 10.3168/jds.2015-10353] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 10/30/2015] [Indexed: 01/22/2023]
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13
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Xu H, Luo J, Zhao W, Yang Y, Tian H, Shi H, Bionaz M. Overexpression of SREBP1 (sterol regulatory element binding protein 1) promotes de novo fatty acid synthesis and triacylglycerol accumulation in goat mammary epithelial cells. J Dairy Sci 2016; 99:783-95. [DOI: 10.3168/jds.2015-9736] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 09/22/2015] [Indexed: 01/13/2023]
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14
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Bionaz M, Osorio J, Loor JJ. TRIENNIAL LACTATION SYMPOSIUM: Nutrigenomics in dairy cows: Nutrients, transcription factors, and techniques1,2. J Anim Sci 2015; 93:5531-53. [DOI: 10.2527/jas.2015-9192] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- M. Bionaz
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis 97333
| | - J. Osorio
- Department of Animal and Rangeland Sciences, Oregon State University, Corvallis 97333
| | - J. J. Loor
- Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana 61801
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15
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Regulation of the fatty acid synthase promoter by liver X receptor α through direct and indirect mechanisms in goat mammary epithelial cells. Comp Biochem Physiol B Biochem Mol Biol 2015; 184:44-51. [DOI: 10.1016/j.cbpb.2015.02.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 02/20/2015] [Accepted: 02/23/2015] [Indexed: 11/20/2022]
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16
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Ma L, Lengi A, McGilliard M, Bauman D, Corl B. Short communication: Effect of trans-10,cis-12 conjugated linoleic acid on activation of lipogenic transcription factors in bovine mammary epithelial cells. J Dairy Sci 2014; 97:5001-6. [DOI: 10.3168/jds.2013-7555] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 04/30/2014] [Indexed: 12/25/2022]
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17
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Harvatine KJ, Boisclair YR, Bauman DE. Liver x receptors stimulate lipogenesis in bovine mammary epithelial cell culture but do not appear to be involved in diet-induced milk fat depression in cows. Physiol Rep 2014; 2:e00266. [PMID: 24760520 PMCID: PMC4002246 DOI: 10.1002/phy2.266] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Abstract Milk fat synthesis of ruminants can be inhibited by intermediates of ruminal fatty acid biohydrogenation including trans-10, cis-12 conjugated linoleic acid (CLA). These biohydrogenation intermediates signal a coordinated downregulation of genes involved in mammary FA synthesis, transport, and esterification. We have previously reported decreased mammary expression of sterol response element-binding protein 1 (SREBP1), SREBP1-activating proteins, and thyroid hormone-responsive spot 14 (S14) in the cow during diet-induced milk fat depression (MFD), and treatment with trans-10, cis-12 CLA. Liver x receptors (LXR) and retinoid x receptors (RXR) regulate lipogenesis and are known to bind polyunsaturated FA and LXR agonist increases lipid synthesis in mammary epithelial cell culture. The current studies investigated if biohydrogenation products of rumen origin inhibit mammary lipogenesis through LXR and/or RXR. Expression of LXRs was not different in lactating compared to nonlactating bovine mammary tissue, and expression of LXRs, RXRα, and selected LXR and RXR target genes was not changed in mammary tissue during diet-induced or CLA-induced MFD in the cow. In bovine mammary epithelial cell culture, LXR agonist stimulated lipogenesis and expression of LXRß, ATP-binding cassette 1 (ABCA1), SREBP1c, and S14, but LXR activation did not overcome CLA inhibition of lipogenesis and downregulation of LXRß, SREBP1c, and S14 expression. Lastly, expression of the LXR-regulated carbohydrate-responsive element-binding protein (ChREBP) was higher in lactating than nonlactating tissue and was decreased during CLA-induced MFD. We conclude that changes in mammary LXR expression in dairy cows are not involved in MFD and that trans-10, cis-12 CLA inhibition of lipogenesis and diet-induced MFD appears independent of direct LXR signaling.
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Affiliation(s)
- Kevin J Harvatine
- Department of Animal Science, Penn State University, University Park, Pennsylvania
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18
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Oppi-Williams C, Suagee J, Corl B. Regulation of lipid synthesis by liver X receptor α and sterol regulatory element-binding protein 1 in mammary epithelial cells. J Dairy Sci 2013; 96:112-21. [DOI: 10.3168/jds.2011-5276] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 09/07/2012] [Indexed: 01/29/2023]
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19
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Angulo J, Hiller B, Albrecht E, Olivera M, Mahecha L, Nuernberg G, Dannenberger D, Nuernberg K. Effect of different dietary fats on protein expression of sterol regulatory element-binding protein 1 (SREBP-1) in mammary gland tissue of lactating cows. Livest Sci 2012. [DOI: 10.1016/j.livsci.2011.10.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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20
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Effects of polyunsaturated fatty acids from plant oils and algae on milk fat yield and composition are associated with mammary lipogenic and SREBF1 gene expression. Animal 2012; 6:1961-72. [DOI: 10.1017/s1751731112000845] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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