Limits...
Function of SREBP1 in the milk fat synthesis of dairy cow mammary epithelial cells.

Li N, Zhao F, Wei C, Liang M, Zhang N, Wang C, Li QZ, Gao XJ - Int J Mol Sci (2014)

Bottom Line: Recent studies have found that mTORC1 (the mammalian target of rapamycin C1) regulates SREBP1 to promote fat synthesis.SREBP1 was found to be a positive regulator of milk fat synthesis and was shown to be regulated by stearic acid and serum.These findings indicate that SREBP1 is the key positive regulator in milk fat synthesis.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Agricultural Biological Functional Genes, Northeast Agricultural University, Harbin 150030, China. linan0829@163.com.

ABSTRACT
Sterol regulatory element-binding proteins (SREBPs) belong to a family of nuclear transcription factors. The question of which is the most important positive regulator in milk fat synthesis in dairy cow mammary epithelial cells (DCMECs) between SREBPs or other nuclear transcription factors, such as peroxisome proliferator-activated receptor γ (PPARγ), remains a controversial one. Recent studies have found that mTORC1 (the mammalian target of rapamycin C1) regulates SREBP1 to promote fat synthesis. Thus far, however, the interaction between the SREBP1 and mTOR (the mammalian target of rapamycin) pathways in the regulation of milk fat synthesis remains poorly understood. This study aimed to identify the function of SREBP1 in milk fat synthesis and to characterize the relationship between SREBP1 and mTOR in DCMECs. The effects of SREBP1 overexpression and gene silencing on milk fat synthesis and the effects of stearic acid and serum on SREBP1 expression in the upregulation of milk fat synthesis were investigated in DCMECs using immunostaining, Western blotting, real-time quantitative PCR, lipid droplet staining, and detection kits for triglyceride content. SREBP1 was found to be a positive regulator of milk fat synthesis and was shown to be regulated by stearic acid and serum. These findings indicate that SREBP1 is the key positive regulator in milk fat synthesis.

Show MeSH
Effect of SREBP1 gene silencing on the subcellular localization of molecules related to milk fat synthesis in DCMECs. Groups of DCMECs were assessed as in Figure 2. (A) Localization and integral optical density analysis of SREBP1 and p-mTOR. SREBP1 and p-mTOR (green), giantin (purple), and DAPI (blue). Scale bars = 10 μm; (B) Integral optical density analysis of SREBP1 and p-mTOR. p-mTOR (green), giantin (purple), and DAPI (blue). Scale bars = 10 μm; and (C,D) Immunofluorescent staining and integral optical density analysis of lipid droplets were performed on DCMECs. Lipid droplet (green) and DAPI (blue). Scale bars = 10 or 15 μm. Values represent means ± SE (n = 3). ** p < 0.01 compared with negative control group.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4200870&req=5

ijms-15-16998-f003: Effect of SREBP1 gene silencing on the subcellular localization of molecules related to milk fat synthesis in DCMECs. Groups of DCMECs were assessed as in Figure 2. (A) Localization and integral optical density analysis of SREBP1 and p-mTOR. SREBP1 and p-mTOR (green), giantin (purple), and DAPI (blue). Scale bars = 10 μm; (B) Integral optical density analysis of SREBP1 and p-mTOR. p-mTOR (green), giantin (purple), and DAPI (blue). Scale bars = 10 μm; and (C,D) Immunofluorescent staining and integral optical density analysis of lipid droplets were performed on DCMECs. Lipid droplet (green) and DAPI (blue). Scale bars = 10 or 15 μm. Values represent means ± SE (n = 3). ** p < 0.01 compared with negative control group.

Mentions: Lower expression levels of SREBP1 (Figure 3A,B) and p-mTOR (Figure 3C,D) in response to SREBP1 gene silencing were also demonstrated by immunofluorescence microscopy. SREBP1 gene silencing in DCMECs was further found to result in significantly decreased lipid droplet content (Figure 3E). These results are in accord with the aforementioned conclusion, further revealing SREBP1 as a key positive regulator in milk fat synthesis in DCMECs.


Function of SREBP1 in the milk fat synthesis of dairy cow mammary epithelial cells.

Li N, Zhao F, Wei C, Liang M, Zhang N, Wang C, Li QZ, Gao XJ - Int J Mol Sci (2014)

Effect of SREBP1 gene silencing on the subcellular localization of molecules related to milk fat synthesis in DCMECs. Groups of DCMECs were assessed as in Figure 2. (A) Localization and integral optical density analysis of SREBP1 and p-mTOR. SREBP1 and p-mTOR (green), giantin (purple), and DAPI (blue). Scale bars = 10 μm; (B) Integral optical density analysis of SREBP1 and p-mTOR. p-mTOR (green), giantin (purple), and DAPI (blue). Scale bars = 10 μm; and (C,D) Immunofluorescent staining and integral optical density analysis of lipid droplets were performed on DCMECs. Lipid droplet (green) and DAPI (blue). Scale bars = 10 or 15 μm. Values represent means ± SE (n = 3). ** p < 0.01 compared with negative control group.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4200870&req=5

ijms-15-16998-f003: Effect of SREBP1 gene silencing on the subcellular localization of molecules related to milk fat synthesis in DCMECs. Groups of DCMECs were assessed as in Figure 2. (A) Localization and integral optical density analysis of SREBP1 and p-mTOR. SREBP1 and p-mTOR (green), giantin (purple), and DAPI (blue). Scale bars = 10 μm; (B) Integral optical density analysis of SREBP1 and p-mTOR. p-mTOR (green), giantin (purple), and DAPI (blue). Scale bars = 10 μm; and (C,D) Immunofluorescent staining and integral optical density analysis of lipid droplets were performed on DCMECs. Lipid droplet (green) and DAPI (blue). Scale bars = 10 or 15 μm. Values represent means ± SE (n = 3). ** p < 0.01 compared with negative control group.
Mentions: Lower expression levels of SREBP1 (Figure 3A,B) and p-mTOR (Figure 3C,D) in response to SREBP1 gene silencing were also demonstrated by immunofluorescence microscopy. SREBP1 gene silencing in DCMECs was further found to result in significantly decreased lipid droplet content (Figure 3E). These results are in accord with the aforementioned conclusion, further revealing SREBP1 as a key positive regulator in milk fat synthesis in DCMECs.

Bottom Line: Recent studies have found that mTORC1 (the mammalian target of rapamycin C1) regulates SREBP1 to promote fat synthesis.SREBP1 was found to be a positive regulator of milk fat synthesis and was shown to be regulated by stearic acid and serum.These findings indicate that SREBP1 is the key positive regulator in milk fat synthesis.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Agricultural Biological Functional Genes, Northeast Agricultural University, Harbin 150030, China. linan0829@163.com.

ABSTRACT
Sterol regulatory element-binding proteins (SREBPs) belong to a family of nuclear transcription factors. The question of which is the most important positive regulator in milk fat synthesis in dairy cow mammary epithelial cells (DCMECs) between SREBPs or other nuclear transcription factors, such as peroxisome proliferator-activated receptor γ (PPARγ), remains a controversial one. Recent studies have found that mTORC1 (the mammalian target of rapamycin C1) regulates SREBP1 to promote fat synthesis. Thus far, however, the interaction between the SREBP1 and mTOR (the mammalian target of rapamycin) pathways in the regulation of milk fat synthesis remains poorly understood. This study aimed to identify the function of SREBP1 in milk fat synthesis and to characterize the relationship between SREBP1 and mTOR in DCMECs. The effects of SREBP1 overexpression and gene silencing on milk fat synthesis and the effects of stearic acid and serum on SREBP1 expression in the upregulation of milk fat synthesis were investigated in DCMECs using immunostaining, Western blotting, real-time quantitative PCR, lipid droplet staining, and detection kits for triglyceride content. SREBP1 was found to be a positive regulator of milk fat synthesis and was shown to be regulated by stearic acid and serum. These findings indicate that SREBP1 is the key positive regulator in milk fat synthesis.

Show MeSH