Mao Guochao, Ren Pengyu, Wang Gang, Yan Feng, Zhang Yuelin
Medical School of Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, People's Republic of China.
Department of Neurosurgery, The Third Affiliated Hospital, Medical School of Xi'an Jiaotong University, 76 Yanta West Road, Xi'an, Shaanxi, 710061, People's Republic of China.
J Mol Neurosci. 2017 Feb;61(2):152-158. doi: 10.1007/s12031-016-0871-z. Epub 2016 Nov 30.
The p38α, also named Mapk14, is a pro-apoptotic protein, which is reported to be downregulated 2 h after cerebral ischemia. However, little is known what causes the downregulation of p38α protein level. Here, we studied the effect of cerebral ischemia on p38α mRNA expression and p38α protein level in brain of mice. We found that p38α protein level is reduced after middle cerebral artery occlusion. However, at the meantime, p38α mRNA expression has no detectable changes, suggesting that the possible posttranscription is regulated by ischemia. To reveal the mechanism for posttranscription of p38α protein, we tested the effect of miR-128-3p. Using luciferase reporter assay, we found that miR-128-3p could directly target p38α 3'UTR. We further tested the effect of miR-128-3p on the p38α protein level. We found that miR-128-3p strongly decreased the p38α protein level in SH-SY5Y cells after the cells were transfected with miR-128-3p using lentivirus vector containing precursor its RNA sequences. We further found that inhibition of miR-128-3p enhanced the infarct volume of brain in mice. Our study thus confirms that miR-128-3p can downregulate p38α protein level through posttranscription and increase of miR-128-3p level may contribute to neuronal survival in ischemia-induced brain injury.
p38α，也称为Mapk14，是一种促凋亡蛋白，据报道在脑缺血2小时后表达下调。然而，p38α蛋白水平下调的原因尚不清楚。在此，我们研究了脑缺血对小鼠脑中p38α mRNA表达和p38α蛋白水平的影响。我们发现大脑中动脉闭塞后p38α蛋白水平降低。然而，与此同时，p38α mRNA表达没有可检测到的变化，这表明转录后可能受缺血调控。为了揭示p38α蛋白转录后的机制，我们测试了miR-128-3p的作用。使用荧光素酶报告基因检测，我们发现miR-128-3p可以直接靶向p38α 3'UTR。我们进一步测试了miR-128-3p对p38α蛋白水平的影响。我们发现，使用含有其RNA序列前体的慢病毒载体将miR-128-3p转染到SH-SY5Y细胞后，miR-128-3p显著降低了p38α蛋白水平。我们进一步发现抑制miR-128-3p会增加小鼠脑梗死体积。因此，我们的研究证实miR-128-3p可以通过转录后下调p38α蛋白水平，miR-128-3p水平的升高可能有助于缺血性脑损伤中的神经元存活。
