Kole H K, Garant M J, Kole S, Bernier M
Diabetes Section, Laboratory of Clinical Physiology, NIA, National Institutes of Health, Baltimore, Maryland 21224, USA.
J Biol Chem. 1996 Jun 14;271(24):14302-7. doi: 10.1074/jbc.271.24.14302.
3S-peptide-I is a synthetic tris-sulfotyrosyl dodecapeptide corresponding to the major site of insulin receptor autophosphorylation that potently inhibits dephosphorylation of the insulin receptor in a cell-free system and in digitonin-permeabilized Chinese hamster ovary (CHO) cells overexpressing the human insulin receptors (CHO/HIRc cells) (Liotta, A. S., Kole, H. K., Fales, H. M., Roth, J., and Bernier, M. (1994) J. Biol. Chem. 269, 22996-23001). In the present study, we found that 3S-peptide-I was not capable of inhibiting dephosphorylation of the epidermal growth factor (EGF) receptors in digitonin-permeabilized CHO cells that overexpress human EGF receptors (CHO/EGF-R cells). Moreover, the addition of a N-stearyl derivative of 3S-peptide-I to intact CHO/HIRc cells caused a concentration-dependent increase in insulin-stimulated phosphorylation of the insulin receptor, with a maximum effect (approximately 2.7-fold) at 50 microM. In contrast, ligand-stimulated EGF receptor phosphorylation in CHO/EGF-R cells was not affected by the presence of stearyl 3S-peptide-I. Furthermore, treatment of CHO/HIRc cells with this N-stearyl peptide led to a significant enhancement of the insulin-induced association of phosphatidylinositol (PI) 3-kinase activity with insulin receptor substrate 1 and the activation of mitogen-activated protein kinase. However, stearyl 3S-peptide-I had no effect on the EGF-stimulated activation of PI-3-kinase and mitogen-activated protein kinase in CHO/EGF-R cells. These data indicate that this tris-sulfotyrosyl dodecapeptide selectively enhances insulin signal transduction by specifically inhibiting dephosphorylation of the insulin receptor in intact cells.
3S-肽-I是一种合成的三磺基酪氨酸十二肽，对应于胰岛素受体自身磷酸化的主要位点，在无细胞系统和过表达人胰岛素受体的洋地黄皂苷通透化中国仓鼠卵巢（CHO）细胞（CHO/HIRc细胞）中能有效抑制胰岛素受体的去磷酸化（Liotta, A. S., Kole, H. K., Fales, H. M., Roth, J., and Bernier, M. (1994) J. Biol. Chem. 269, 22996 - 23001）。在本研究中，我们发现3S-肽-I不能抑制过表达人表皮生长因子（EGF）受体的洋地黄皂苷通透化CHO细胞（CHO/EGF-R细胞）中EGF受体的去磷酸化。此外，将3S-肽-I 的N-硬脂酰衍生物添加到完整的CHO/HIRc细胞中会导致胰岛素刺激的胰岛素受体磷酸化呈浓度依赖性增加，在50 μM时达到最大效应（约2.7倍）。相比之下，硬脂酰3S-肽-I的存在并不影响CHO/EGF-R细胞中配体刺激的EGF受体磷酸化。此外，用这种N-硬脂酰肽处理CHO/HIRc细胞会导致胰岛素诱导的磷脂酰肌醇（PI）3-激酶活性与胰岛素受体底物1的结合显著增强，以及丝裂原活化蛋白激酶的激活。然而，硬脂酰3S-肽-I对CHO/EGF-R细胞中EGF刺激的PI-3-激酶和丝裂原活化蛋白激酶的激活没有影响。这些数据表明，这种三磺基酪氨酸十二肽通过特异性抑制完整细胞中胰岛素受体的去磷酸化来选择性增强胰岛素信号转导。
