1 Laboratory of Neuroimmunoendocrinology, National Institute of Neurology and Neurosurgery Manuel Velasco Suarez, Mexico.
*These authors contributed equally to this work.
ASN Neuro. 2019 Jan-Dec;11:1759091419832444. doi: 10.1177/1759091419832444.
Phosphodiesterases (PDEs) have previously been implicated in oligodendrocyte maturation and myelination of central nervous system axons. Sildenafil citrate is a phosphodiesterase inhibitor known to block PDE5, which also reduces inflammation in the experimental autoimmune encephalomyelitis demyelinating model. To find out whether this inhibitor might exert beneficial effects on central nervous system myelin repair activities, we investigated to what degree sildenafil modulates differentiation and maturation of cultured primary rat oligodendroglial precursor cells (OPCs). To this end, gene and protein expression of 2',3'-cyclic-nucleotide 3'-phosphodiesterase, myelin basic protein, and myelin oligodendrocyte glycoprotein, as well as of negative regulators of myelin expression (Hes1, Hes5, Id2, Id4, Rock2, and p57Kip2) were measured in OPCs treated with sildenafil. Moreover, the subcellular distribution of the p57kip2 protein was determined after sildenafil treatment, as this revealed to be an early predictor of the oligodendroglial differentiation capacity. In vitro myelination assays were done to measure the myelination capacity of oligodendrocytes treated with sildenafil. We found that sildenafil significantly diminished myelin gene expression and protein expression. Moreover, sildenafil also increased the expression of Id2 and Id4 negative transcriptional regulators, and the degree of OPCs with cytoplasmic p57kip2 protein localization was reduced, providing evidence that the PDE blocker impaired the differentiation capacity. Finally, sildenafil also interfered with the establishment of internodes as revealed by in vitro myelination assays. We therefore conclude that blocking PDE5 activities exerts a negative impact on intrinsic oligodendroglial differentiation processes.
磷酸二酯酶（PDEs）先前被认为参与少突胶质细胞成熟和中枢神经系统轴突髓鞘形成。枸橼酸西地那非是一种磷酸二酯酶抑制剂，已知可阻断 PDE5，从而减少实验性自身免疫性脑脊髓炎脱髓鞘模型中的炎症。为了确定这种抑制剂是否对中枢神经系统髓鞘修复活动有有益作用，我们研究了西地那非在多大程度上调节培养的原代大鼠少突胶质前体细胞（OPC）的分化和成熟。为此，我们测量了西地那非处理的 OPC 中 2'，3'-环核苷酸 3'-磷酸二酯酶、髓鞘碱性蛋白和髓鞘少突胶质糖蛋白的基因和蛋白表达，以及髓鞘表达的负调节因子（Hes1、Hes5、Id2、Id4、Rock2 和 p57Kip2）。此外，还测定了西地那非处理后 p57kip2 蛋白的亚细胞分布，因为这是少突胶质细胞分化能力的早期预测指标。进行体外髓鞘形成测定以测量经西地那非处理的少突胶质细胞的髓鞘形成能力。我们发现西地那非显著降低了髓鞘基因和蛋白的表达。此外，西地那非还增加了 Id2 和 Id4 负转录调节因子的表达，并且具有细胞质 p57kip2 蛋白定位的 OPC 比例降低，这表明 PDE 阻断剂损害了分化能力。最后，体外髓鞘形成测定还表明，西地那非还干扰了节间的建立。因此，我们得出结论，阻断 PDE5 活性对内在的少突胶质细胞分化过程产生负面影响。
