Henry R R, Abrams L, Nikoulina S, Ciaraldi T P
Department of Medicine, University of California, San Diego, La Jolla, USA.
Diabetes. 1995 Aug;44(8):936-46. doi: 10.2337/diab.44.8.936.
Myoblasts from human skeletal muscle were isolated from needle biopsy samples of vastus lateralis and fused to differentiated multinucleated myotubes. Specific high-affinity insulin and insulin-like growth factor I (IGF-I) binding, glucose transporter proteins GLUT1 and GLUT4, glycogen synthase and pyruvate dehydrogenase proteins, and their specific mRNAs were identified in fused myotubes. Insulin and IGF-I stimulated 2-deoxyglucose uptake twofold with half-maximal stimulation by insulin at 0.98 +/- 0.12 nmol/l and maximal stimulation at 17.5 nmol/l. Acute insulin treatment (33 nmol/l) doubled glycogen synthase activity and glucose incorporation into glycogen while increasing pyruvate dehydrogenase approximately 30%. In cells cultured from NIDDM subjects, both basal (6.9 +/- 1.0 vs. 13.0 +/- 1.7 pmol.mg protein-1.min-1) and acute insulin-stimulated transport (13.5 +/- 2.0 vs. 22.4 +/- 1.3 pmol.mg protein-1.min-1) were significantly reduced compared with nondiabetic control subjects (both P < or = 0.005). GLUT1 protein content of total membranes from NIDDM subjects was decreased compared with control subjects, while GLUT4 levels were similar between groups. A significant correlation (r = 0.65, P < or = 0.05) was present when maximal rates of insulin-stimulated glucose transport in cell culture from subjects were compared with their corresponding in vivo glucose disposal determined by hyperinsulinemic glucose clamp. In summary, differentiated human skeletal muscle cultures exhibit biochemical and molecular features of insulin-stimulated glucose transport and intracellular enzyme activity comparable with the in vivo situation. Defective insulin-stimulated glucose transport persists in muscle cultures from NIDDM subjects and resembles the reduced insulin-mediated glucose uptake present in vivo. We conclude that this technique provides a relevant cellular model to study insulin action and glucose metabolism in normal subjects and determine the mechanisms of insulin resistance in NIDDM.
从股外侧肌的针吸活检样本中分离出人类骨骼肌成肌细胞，并使其融合形成分化的多核肌管。在融合的肌管中鉴定出了特异性高亲和力胰岛素和胰岛素样生长因子I（IGF-I）结合蛋白、葡萄糖转运蛋白GLUT1和GLUT4、糖原合酶和丙酮酸脱氢酶蛋白及其特异性mRNA。胰岛素和IGF-I使2-脱氧葡萄糖摄取增加了两倍，胰岛素在0.98±0.12 nmol/l时产生半数最大刺激，在17.5 nmol/l时产生最大刺激。急性胰岛素处理（33 nmol/l）使糖原合酶活性和葡萄糖掺入糖原的量增加了一倍，同时使丙酮酸脱氢酶增加了约30%。在非胰岛素依赖型糖尿病（NIDDM）患者培养的细胞中，基础状态下（6.9±1.0对13.0±1.7 pmol·mg蛋白⁻¹·min⁻¹）和急性胰岛素刺激的转运（13.5±2.0对22.4±1.3 pmol·mg蛋白⁻¹·min⁻¹）与非糖尿病对照患者相比均显著降低（P均≤0.005）。与对照患者相比，NIDDM患者总膜中的GLUT1蛋白含量降低，而两组间GLUT4水平相似。将患者细胞培养中胰岛素刺激的葡萄糖转运最大速率与其通过高胰岛素葡萄糖钳夹测定的相应体内葡萄糖处置情况进行比较时，存在显著相关性（r = 0.65，P≤0.05）。总之，分化的人类骨骼肌培养物表现出胰岛素刺激的葡萄糖转运和细胞内酶活性的生化及分子特征，与体内情况相当。NIDDM患者的肌肉培养物中存在胰岛素刺激的葡萄糖转运缺陷，且类似于体内胰岛素介导的葡萄糖摄取减少。我们得出结论，该技术为研究正常受试者的胰岛素作用和葡萄糖代谢以及确定NIDDM中胰岛素抵抗的机制提供了一个相关的细胞模型。
