Departament de Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona Barcelona, Spain.
Front Endocrinol (Lausanne). 2012 Apr 26;3:55. doi: 10.3389/fendo.2012.00055. eCollection 2012.
Primary cultures of gilthead sea bream myocytes were performed in order to examine the relative metabolic function of insulin compared with IGF-I and IGF-II (insulin-like growth factors, IGFs) at different stages in the cell culture. In these cells, the in vitro effects of insulin and IGFs on 2-deoxyglucose (2-DG) and l-alanine uptake were studied in both myocytes (day 4) and small myotubes (day 9). 2-DG uptake in gilthead sea bream muscle cells was increased in the presence of insulin and IGFs in a time dependent manner and along with muscle cell differentiation. On the contrary, l-alanine uptake was also stimulated by insulin and IGFs but showed an inverse pattern, being the uptake higher in small myocytes than in large myotubes. The results of preincubation with inhibitors (PD-98059, wortmannin, and cytochalasin B) on 2-DG uptake indicated that insulin and IGFs stimulate glucose uptake through the same mechanisms, and evidenced that mitogenesis activator protein kinase (MAPK) and PI3K-Akt transduction pathways mediate the metabolic function of these peptides. In the same way, we observed that GLUT4 protein synthesis was stimulated in the presence of insulin and IGFs in gilthead sea bream muscle cells in a different manner at days 4 or 9 of the culture. In summary we describe here, for the first time, the effects of insulin and IGFs on 2-DG and l-alanine uptake in primary culture of gilthead sea bream muscle cells. We show that both MAPK and PI3K-Akt transduction pathways are needed in order to control insulin and IGFs actions in these cells. Moreover, changes in glucose uptake can be explained by the action of the GLUT4 transporter, which is stimulated in the presence of insulin and IGFs throughout the cell culture.
为了研究胰岛素与 IGF-I 和 IGF-II（胰岛素样生长因子，IGFs）在细胞培养不同阶段的相对代谢功能，我们进行了金头鲷肌细胞的原代培养。在这些细胞中，研究了胰岛素和 IGFs 对 2-脱氧葡萄糖（2-DG）和 l-丙氨酸摄取的体外作用，分别在肌细胞（第 4 天）和小肌管（第 9 天）中进行。2-DG 在金头鲷肌肉细胞中的摄取随时间呈依赖性增加，并伴随着肌肉细胞分化。相反，胰岛素和 IGFs 也刺激了 l-丙氨酸的摄取，但呈相反的模式，即在小肌细胞中的摄取高于大肌管。用抑制剂（PD-98059、wortmannin 和细胞松弛素 B）预孵育对 2-DG 摄取的结果表明，胰岛素和 IGFs 通过相同的机制刺激葡萄糖摄取，并证明丝裂原激活蛋白激酶（MAPK）和 PI3K-Akt 转导途径介导这些肽的代谢功能。同样，我们观察到在金头鲷肌肉细胞培养的第 4 天或第 9 天，胰岛素和 IGFs 以不同的方式刺激 GLUT4 蛋白的合成。总之，我们在这里首次描述了胰岛素和 IGFs 对金头鲷肌肉细胞原代培养中 2-DG 和 l-丙氨酸摄取的影响。我们表明，MAPK 和 PI3K-Akt 转导途径都需要控制这些细胞中胰岛素和 IGFs 的作用。此外，葡萄糖摄取的变化可以通过 GLUT4 转运体的作用来解释，该转运体在胰岛素和 IGFs 的存在下整个细胞培养过程中都受到刺激。
