Gondret F, Guitton N, Guillerm-Regost C, Louveau I
Institut National de la Recherche Agronomique (INRA), Unité Mixte de Recherches (UMR) 1079 Systèmes d'Elevage Nutrition Animale et Humaine, Saint-Gilles, 35590, France.
J Anim Sci. 2008 Sep;86(9):2115-25. doi: 10.2527/jas.2007-0750. Epub 2008 Feb 29.
The content and distribution of body lipids are of special interest for production efficiency and meat quality in the farm animal industry. Triglycerides represent the most variable fraction of tissue lipids, and are mainly stored in adipocytes. Although several studies have reported regional differences in the expression of genes and their products in adipocytes from various species, the characteristics of i.m. adipocytes remain poorly described. To evaluate adipocyte features according to muscle and other fat locations, adipocyte proteins were isolated from trapezius skeletal muscle, and intermuscular, s.c., or perirenal adipose tissues from 6 female pigs (80 d of age). Protein extracts were labeled and analyzed by 2-dimensional, fluorescent, differential gel electrophoresis. The comparisons revealed that 149 spots were always differentially expressed (P < 0.05, ratio exceeding |2|-fold difference) between i.m. adipocytes and the fat cells derived from the 3 other adipose locations. The proteins that were downregulated in i.m. fat cells belonged to various metabolic pathways, such as lipogenesis (cytosolic malate dehydrogenase and isocitrate dehydrogenase, P < 0.01), glycolysis (enolases and aldolase, P </= 0.01), lipolysis (perilipin, P < 0.01), fatty acid oxidation (long-chain fatty-acyl CoA dehydrogenase, P < 0.01), and energy transfer (catalase, voltage-dependent anion channel 1, and electron-transfer flavoprotein, P < 0.05). In contrast, both prohibitin-1 and cell division cycle 42 homolog, with possible roles in cell growth, were up-regulated (P < 0.05) in i.m. adipocytes compared with other fat cells. Fewer differences were observed when adipocytes isolated from s.c., perirenal, and intermuscular fat tissues were compared, with a maximum of 17 spots differing significantly in abundance between perirenal and s.c. adipose tissues. The findings that proteins involved in both anabolic and energy-yielding catabolic pathways are downregulated in i.m. adipocytes compared with s.c., visceral, or intermuscular adipocytes, suggest that the metabolic activity of i.m. adipocytes is low. Thus, triggering adipogenesis rather than cell metabolism per se might be a valuable strategy to control lipid deposition in pig skeletal muscles.
在畜牧养殖业中，动物体内脂质的含量和分布对于生产效率和肉质具有特殊意义。甘油三酯是组织脂质中变化最大的部分，主要储存在脂肪细胞中。尽管已有多项研究报道了不同物种脂肪细胞中基因及其产物表达的区域差异，但关于肌内脂肪细胞的特性仍知之甚少。为了根据肌肉和其他脂肪部位评估脂肪细胞的特征，从6头80日龄的雌性猪的斜方肌骨骼肌、肌间、皮下或肾周脂肪组织中分离出脂肪细胞蛋白。对蛋白质提取物进行标记，并通过二维荧光差异凝胶电泳进行分析。比较结果显示，在肌内脂肪细胞与来自其他3个脂肪部位的脂肪细胞之间，始终有149个斑点存在差异表达（P < 0.05，差异倍数超过|2|倍）。在肌内脂肪细胞中下调的蛋白质属于多种代谢途径，如脂肪生成（胞质苹果酸脱氢酶和异柠檬酸脱氢酶，P < 0.01）、糖酵解（烯醇化酶和醛缩酶，P ≤ 0.01）、脂肪分解（ perilipin，P < 0.01）、脂肪酸氧化（长链脂肪酰基辅酶A脱氢酶，P < 0.01）以及能量转移（过氧化氢酶、电压依赖性阴离子通道1和电子传递黄素蛋白，P < 0.05）。相比之下，与其他脂肪细胞相比，在肌内脂肪细胞中可能在细胞生长中发挥作用的抑制素-1和细胞分裂周期蛋白42同源物均上调（P < 0.05）。当比较从皮下、肾周和肌间脂肪组织分离的脂肪细胞时，观察到的差异较少，肾周和皮下脂肪组织之间最多有17个斑点在丰度上存在显著差异。与皮下、内脏或肌间脂肪细胞相比，肌内脂肪细胞中参与合成代谢和产生能量的分解代谢途径的蛋白质均下调，这一发现表明肌内脂肪细胞的代谢活性较低。因此，触发脂肪生成而非细胞代谢本身可能是控制猪骨骼肌脂质沉积的一种有价值的策略。
