Laboratory of Biochemistry and Molecular Biology of the Exercise, School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil.
Med Sci Sports Exerc. 2012 Aug;44(8):1453-62. doi: 10.1249/MSS.0b013e31824e8a36.
MicroRNA (miRNA)-126 is angiogenic and has two validated targets: Sprouty-related protein 1 (Spred-1) and phosphoinositol-3 kinase regulatory subunit 2 (PI3KR2), negative regulators of angiogenesis by VEGF pathway inhibition. We investigated the role of swimming training on cardiac miRNA-126 expression related to angiogenesis.
Female Wistar rats were assigned to three groups: sedentary (S), training 1 (T1, moderate volume), and training 2 (T2, high volume). T1 consisted of 60 min·d of swimming, five times per week for 10 wk with 5% body overload. T2 consisted of the same protocol of T1 until the eighth week; in the ninth week, rats trained for two times a day, and in the 10th week, rats trained for three times a day. MiRNA and PI3KR2 gene expression analysis was performed by real-time polymerase chain reaction in heart muscle. We assessed markers of training, the cardiac capillary-fiber ratio, cardiac protein expression of VEGF, Spred-1, Raf-1/ERK 1/2, and PI3K/Akt/eNOS.
The cardiac capillary-fiber ratio increased in T1 (58%) and T2 (101%) compared with S. VEGF protein expression was increased 42% in T1 and 108% in T2. Cardiac miRNA-126 expression increased 26% (T1) and 42% (T2) compared with S, correlated with angiogenesis. The miRNA-126 target Spred-1 protein level decreased 41% (T1) and 39% (T2), which consequently favored an increase in angiogenic signaling pathway Raf-1/ERK 1/2. On the other hand, the gene expression of PI3KR2, the other miRNA-126 target, was reduced 39% (T1) and 78% (T2), and there was an increase in protein expression of components of the PI3K/Akt/eNOS signaling pathway in the trained groups.
This study showed that aerobic training promotes an increase in the expression of miRNA-126 and that this may be related to exercise-induced cardiac angiogenesis, by indirect regulation of the VEGF pathway and direct regulation of its targets that converged in an increase in angiogenic pathways, such as MAPK and PI3K/Akt/eNOS.
微小 RNA（miRNA）-126 具有血管生成作用，有两个经过验证的靶点：Spred-1 和磷酸肌醇-3 激酶调节亚基 2（PI3KR2），它们是通过 VEGF 通路抑制来抑制血管生成的负调节剂。我们研究了游泳训练对心脏 miRNA-126 表达与血管生成相关的作用。
将雌性 Wistar 大鼠分为三组：安静组（S）、训练 1 组（T1，中等量）和训练 2 组（T2，大量）。T1 组包括 60 分钟·天的游泳，每周 5 次，持续 10 周，外加 5%的身体负荷。T2 组前 8 周的方案与 T1 组相同；第 9 周，大鼠每天训练两次；第 10 周，大鼠每天训练三次。通过实时聚合酶链反应分析心肌中的 miRNA 和 PI3KR2 基因表达。我们评估了训练标志物、心脏毛细血管-纤维比、心脏 VEGF、Spred-1、Raf-1/ERK 1/2 和 PI3K/Akt/eNOS 蛋白表达。
与 S 组相比，T1 组（58%）和 T2 组（101%）心脏毛细血管-纤维比增加。T1 组 VEGF 蛋白表达增加 42%，T2 组增加 108%。与 S 组相比，T1 组和 T2 组心脏 miRNA-126 表达分别增加 26%和 42%，与血管生成相关。miRNA-126 的靶标 Spred-1 蛋白水平降低 41%（T1）和 39%（T2），这有利于血管生成信号通路 Raf-1/ERK 1/2 的增加。另一方面，另一个 miRNA-126 靶点 PI3KR2 的基因表达降低 39%（T1）和 78%（T2），训练组中 PI3K/Akt/eNOS 信号通路的蛋白表达增加。
本研究表明，有氧运动训练可促进 miRNA-126 的表达增加，这可能与运动诱导的心脏血管生成有关，通过间接调节 VEGF 通路和直接调节其靶点，这些靶点集中在 MAPK 和 PI3K/Akt/eNOS 等血管生成途径上。
