Laboratory of Neuroinflammation, Hospital Nacional de Parapléjicos-SESCAM, 45071, Toledo, Spain,
J Neuroimmune Pharmacol. 2015 Jun;10(2):309-17. doi: 10.1007/s11481-015-9609-x. Epub 2015 Apr 22.
A basal tone of the endocannabinoid 2-arachidonoylglycerol (2-AG) enhances late oligodendrocyte progenitor cell (OPC) differentiation. Here, we investigated whether endogenous 2-AG may also promote OPC proliferation in earlier stages. We found that the blockade of 2-AG synthesizing enzymes, sn-1-diacylglycerol lipases α and β (DAGLs), with RHC-80267 or the antagonism of either CB1 or CB2 cannabinoid receptors with AM281 and AM630, respectively, impaired early OPC proliferation stimulated by platelet-derived growth factor (PDGF-AA) and basic fibroblast growth factor (bFGF). On the contrary, increasing the levels of endogenous 2-AG by blocking the degradative enzyme monoacylglycerol lipase (MAGL) with JZL-184, significantly increased OPC proliferation as did agonists of cannabinoid receptor CB1 (ACEA), CB2 (JWH133) or both (HU-210). To elucidate signaling pathways underlying OPC proliferation, we studied the involvement of phosphatidylinositol 3-kinase (PI3K)/Akt and its downstream target mammalian target of rapamycin (mTOR). We show that phosphorylation of Akt and mTOR is required for OPC proliferation stimulated by growth factors (PDGF-AA and bFGF) or by CB1/CB2 agonists (ACEA/JWH133), since it was strongly decreased after LY294002 or rapamycin treatment. In line with this, blockade of CB1 (AM281), CB2 (AM630) or DAGLs (RHC-80267), decreased phosphorylation of Akt, mTOR and 4E-BP1, diminished cyclin E-cdk2 complex association and increased p27(kip1) levels. Our data suggest that proliferation of early OPCs stimulated by PDGF-AA and bFGF depends on the tonic activation of cannabinoid receptors by endogenous 2-AG and provide further evidence on the role of endocannabinoids in oligodendrocyte development, being important for the maintenance and self-renewal of the OPCs. The results highlight the therapeutic potential of the endocannabinoid signaling in the emerging field of brain repair.
内源性大麻素 2-花生四烯酰甘油（2-AG）的基础水平增强了晚期少突胶质前体细胞（OPC）的分化。在这里，我们研究了内源性 2-AG 是否也可以促进早期 OPC 的增殖。我们发现，使用 RHC-80267 阻断 2-AG 合成酶 sn-1-二酰基甘油脂肪酶α和β（DAGL），或分别使用 AM281 和 AM630 拮抗大麻素受体 CB1 和 CB2，会损害血小板衍生生长因子（PDGF-AA）和碱性成纤维细胞生长因子（bFGF）刺激的早期 OPC 增殖。相反，通过阻断分解酶单酰基甘油脂肪酶（MAGL）用 JZL-184 增加内源性 2-AG 的水平，显著增加了 OPC 的增殖，大麻素受体 CB1（ACEA）、CB2（JWH133）或两者的激动剂（HU-210）也是如此。为了阐明 OPC 增殖的信号通路，我们研究了磷脂酰肌醇 3-激酶（PI3K）/Akt 及其下游靶标哺乳动物雷帕霉素靶蛋白（mTOR）的参与情况。我们表明，Akt 和 mTOR 的磷酸化是由生长因子（PDGF-AA 和 bFGF）或 CB1/CB2 激动剂（ACEA/JWH133）刺激的 OPC 增殖所必需的，因为在用 LY294002 或雷帕霉素处理后，其强烈降低。与此一致，阻断 CB1（AM281）、CB2（AM630）或 DAGL（RHC-80267）降低了 Akt、mTOR 和 4E-BP1 的磷酸化，减少了细胞周期蛋白 E-cdk2 复合物的结合并增加了 p27(kip1)的水平。我们的数据表明，PDGF-AA 和 bFGF 刺激的早期 OPC 增殖依赖于内源性 2-AG 对大麻素受体的紧张激活，并为内源性大麻素在少突胶质细胞发育中的作用提供了进一步证据，这对于 OPC 的维持和自我更新很重要。这些结果突出了内源性大麻素信号在新兴的大脑修复领域中的治疗潜力。
