Isenovic Esma R, Divald Andras, Milivojevic Nikola, Grgurevic Tamara, Fisher Stanley E, Sowers James R
Department of Medicine, SUNY-Health Science Center, Brooklyn 11203, USA.
Metabolism. 2003 Apr;52(4):482-7. doi: 10.1053/meta.2003.50079.
Insulin-like growth factor-1 (IGF-1) and beta-estradiol (E2) have vasodilatory effects, in part, through stimulation of vascular nitric oxide (NO) production. However, their interactive effects on endothelial nitric oxide synthase (eNOS) and NO production have not been previously studied in endothelial cells (EC). Employing rat aortic EC (RAEC), the effects of acute (20 and 30 minutes) and prolonged (4 hours) stimulation with 100 nmol/L IGF-1 and 1 nmol/L E2 (alone or in combination) were assessed with respect to protein levels and enzymatic activities for phosphatidyl inositol 3-kinase (PI3K) and serine/threonine kinase Akt (Akt), enzymes involved in eNOS activation. Exposure to IGF-1 for 30 minutes or E2 for 20 minutes increased insulin receptor substrate-1 (IRS-1) association with the regulatory (p85) subunit of PI3K, enhanced tyrosine phosphorylation of p85, and increased PI3K activity. Combined treatment had a greater effect on p85 phosphorylation and PI3K activity then either agonist alone. Moreover, IGF-1 and E2 enhanced Akt Ser(473) phosphorylation, with the effect of IGF-1 being much greater. Acute expose to both E2 (20 minutes) and IGF-1 (30 minutes) were associated with an increase in eNOS activity. Prolonged exposure (4 hours) to either IGF-1 or E2 increased expression of the p85 subunit as well as eNOS activity. Pretreatment with PI3K antagonist wortmannin (WT) prevented this increase in eNOS activity. The results suggest that IGF-1 and E2 may interact through PI3K/Akt-related pathways to increase eNOS activity.
胰岛素样生长因子-1（IGF-1）和β-雌二醇（E2）具有血管舒张作用，部分是通过刺激血管一氧化氮（NO）的产生来实现的。然而，它们对内皮型一氧化氮合酶（eNOS）和NO产生的相互作用效应此前尚未在内皮细胞（EC）中进行研究。利用大鼠主动脉内皮细胞（RAEC），评估了用100 nmol/L IGF-1和1 nmol/L E2（单独或联合使用）进行急性（20和30分钟）和长时间（4小时）刺激对参与eNOS激活的磷脂酰肌醇3激酶（PI3K）和丝氨酸/苏氨酸激酶Akt（Akt）的蛋白质水平和酶活性的影响。暴露于IGF-1 30分钟或E2 20分钟会增加胰岛素受体底物-1（IRS-1）与PI3K调节（p85）亚基的结合，增强p85的酪氨酸磷酸化，并增加PI3K活性。联合处理对p85磷酸化和PI3K活性的影响比单独使用任何一种激动剂都更大。此外，IGF-1和E2增强了Akt Ser（473）的磷酸化，其中IGF-1的作用更大。急性暴露于E2（20分钟）和IGF-1（3分钟）均与eNOS活性增加有关。长时间暴露（4小时）于IGF-1或E2会增加p85亚基的表达以及eNOS活性。用PI3K拮抗剂渥曼青霉素（WT）预处理可阻止eNOS活性的这种增加。结果表明，IGF-1和E2可能通过PI3K/Akt相关途径相互作用以增加eNOS活性。
