Department of Animal and Veterinary Sciences, Clemson University, Clemson, SC 29634-0311, USA.
J Anim Sci. 2012 Oct;90(10):3433-41. doi: 10.2527/jas.2011-4972. Epub 2012 Jul 31.
Our objective was to determine if palmitoleic (C16:1 cis-9) acid supplementation to primary bovine adipocytes regulates lipogenic gene expression and rates of lipogenesis. Stromal vascular cells were isolated from subcutaneous and intermuscular fat, propagated, and frozen for use in this study. Cells were passaged 4 times, allowed to reach confluence, held for 2 d, and then differentiated with a standard hormone cocktail (d 0). At d 2, secondary differentiation media containing 1 of 4 concentrations of palmitoleic acid (0, 50, 150, or 300 μM) were added for 10 d. Cells were harvested on d 6 and 12 to assess fatty acid concentrations and gene expression. In addition, (13)C2 and (13)C18:0 stable isotopes were added on d 6 to measure lipogenesis and desaturase activity, respectively. Concentrations of C16:1 and total fatty acids increased (P < 0.05) linearly in response to palmitoleic acid supplement. Concentrations of C18:1 cis-11 and C20:1 cis-13 also increased (P < 0.01) in response to supplementation, suggesting elongation of palmitoleic acid in vitro. Concentrations of C16:1, C18:1 cis-11, and total fatty acids were also greater (P < 0.05) at d 12 compared with d 6. In contrast, C16:0, C18:0, and C18:1 cis-9 concentrations decreased (P < 0.05) in response to palmitoleic acid supplementation and were not affected (P > 0.05) by harvest day. The ratio of C18:1 cis-9/C18:0 and fractional synthetic rate (FSR) of desaturation decreased (P < 0.05) in response to increasing palmitoleic acid supplementation. In addition, FSR of lipogenesis was reduced (P < 0.05) in palmitoleic acid-treated cells. Messenger RNA abundance as determined by real-time quantitative PCR for stearoyl-CoA desaturase 1 (SCD1), fatty acid synthase (FASN), and elongase protein 6 (ELOVL6) genes were reduced (P < 0.05) by palmitoleic acid supplementation. Expression of a β-oxidation gene, carnitine palmitoyltransferase 1A (CPT1A), was upregulated (P < 0.05) with palmitoleic acid supplementation in a dose-responsive manner. Supplementation of palmitoleic acid to bovine adipocytes results in increased incorporation of this fatty acid and its elongation products into the adipocyte, which downregulates SCD1, FASN, and ELOVL6 to decrease lipogenesis and upregulates CPT1A, potentially increasing β-oxidation. These results suggest that palmitoleic acid, an end product of desaturation, can act as a regulator of lipogenesis, desaturation, and β-oxidation in bovine adipocytes.
我们的目标是确定棕榈油酸（C16:1 cis-9）补充剂对原代牛脂肪细胞的脂生成基因表达和脂生成率是否有调节作用。从皮下和肌肉间脂肪中分离出基质血管细胞，进行传代培养并冷冻保存，用于本研究。细胞传代 4 次，达到汇合后，培养 2 天，然后用标准激素鸡尾酒（d0）进行分化。在 d2 时，加入 4 种浓度（0、50、150 或 300μM）的棕榈油酸的次级分化培养基，持续 10 天。在 d6 和 d12 时收获细胞，以评估脂肪酸浓度和基因表达。此外，在 d6 时添加 (13)C2 和 (13)C18:0 稳定同位素，分别测量脂生成和去饱和酶活性。棕榈油酸的补充使 C16:1 和总脂肪酸的浓度呈线性增加（P<0.05）。C18:1 cis-11 和 C20:1 cis-13 的浓度也呈线性增加（P<0.01），表明棕榈油酸在体外的延伸。与 d6 相比，d12 时 C16:1、C18:1 cis-11 和总脂肪酸的浓度也更高（P<0.05）。相比之下，C16:0、C18:0 和 C18:1 cis-9 的浓度在棕榈油酸补充后呈下降趋势（P<0.05），并且不受收获日的影响（P>0.05）。随着棕榈油酸补充的增加，C18:1 cis-9/C18:0 比值和去饱和酶的分数合成率（FSR）呈下降趋势（P<0.05）。此外，棕榈油酸处理的细胞中脂生成的 FSR 降低（P<0.05）。实时定量 PCR 测定的硬脂酰辅酶 A 去饱和酶 1（SCD1）、脂肪酸合酶（FASN）和延伸酶蛋白 6（ELOVL6）基因的信使 RNA 丰度降低（P<0.05）。棕榈油酸的补充以剂量反应的方式上调了 β-氧化基因肉碱棕榈酰转移酶 1A（CPT1A）的表达（P<0.05）。向牛脂肪细胞中添加棕榈油酸会导致这种脂肪酸及其延伸产物更多地掺入脂肪细胞，从而下调 SCD1、FASN 和 ELOVL6 以减少脂生成，并上调 CPT1A，可能增加 β-氧化。这些结果表明，作为去饱和作用的终产物，棕榈油酸可以作为牛脂肪细胞中脂生成、去饱和作用和 β-氧化的调节剂。
