Birge R B, Wadsworth S, Akakura R, Abeysinghe H, Kanojia R, MacIelag M, Desbarats J, Escalante M, Singh K, Sundarababu S, Parris K, Childs G, August A, Siekierka J, Weinstein D E
Laboratory of Molecular Oncology, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
Neuroscience. 2004;124(2):351-66. doi: 10.1016/j.neuroscience.2003.10.013.
FK506 and its non-immunosuppressive derivatives represent a class of pharmacological agents referred to as immunophilin ligands that have been reported to promote neuroregeneration and survival in several experimental models; however their cellular and molecular mechanisms of action have not been well established. Here we characterize a new immunophilin ligand that interacts with both FK506 binding protein 12 (FKBP12) and FKBP52, and demonstrate that JNJ460 induces neurite outgrowth from freshly explanted dorsal root ganglia (DRG) in a Schwann cell-dependent manner. Purified cultures of neurons fail to respond to these drugs, but cultures containing Schwann cells and neurons respond with neurite outgrowth, as do neurons grown in conditioned medium from JNJ460-treated Schwann cells. Using microarray analysis and a transcription reporter assay, we show that JNJ460 induces a series of transcriptional changes that occur in a temporal cascade. Among the Schwann cell-expressed genes upregulated following JNJ460 treatment is the POU transcription factor SCIP, which has been shown to regulate Schwann cell gene transcription and differentiation. JNJ460 potentiated transforming growth factor beta (TGF-beta)-induced transcriptional activation and SCIP induction in Schwann cells, by altering the interaction between FKBP12 and the TGF-beta type I receptor, TbetaR1. Finally, to test whether JNJ460 enhances neurite regeneration in vivo, we treated animals with JNJ460 for 30 days following mechanical transection of the sciatic nerve and demonstrated myelin and axonal hypertrophy at the ultrastructural level. Collectively, these data suggest that Schwann cells play an important role in the biological effects of immunophilin ligands by affecting neuron-glial signaling during regeneration.
The cellular and molecular mechanisms responsible for the regenerative effects of immunophilin ligands are not well understood. Here we show that the neuritogenic effects of JNJ460 in a DRG model depend on interactions between neurons and Schwann cells. Treatment of purified Schwann cells with JNJ460 alters Schwann cell gene expression, and promotes the generation of factors that act on neurons. These data indicate that Schwann cells play an important role in the actions of immunophilin ligands.
FK506及其非免疫抑制衍生物代表一类被称为亲免素配体的药理剂，据报道在几种实验模型中可促进神经再生和存活；然而，它们的细胞和分子作用机制尚未完全明确。在此，我们鉴定了一种新的亲免素配体，它可与FK506结合蛋白12（FKBP12）和FKBP52相互作用，并证明JNJ460以雪旺细胞依赖性方式诱导新鲜分离的背根神经节（DRG）长出神经突。纯化的神经元培养物对这些药物无反应，但含有雪旺细胞和神经元的培养物会以神经突生长做出反应，用JNJ460处理的雪旺细胞的条件培养基中培养的神经元也是如此。通过微阵列分析和转录报告基因检测，我们表明JNJ460诱导了一系列按时间顺序级联发生的转录变化。JNJ460处理后上调的雪旺细胞表达基因中包括POU转录因子SCIP，它已被证明可调节雪旺细胞基因转录和分化。JNJ460通过改变FKBP12与转化生长因子β（TGF-β）I型受体TβR1之间的相互作用，增强了TGF-β诱导的雪旺细胞转录激活和SCIP诱导。最后，为了测试JNJ460是否能在体内增强神经突再生，我们在坐骨神经机械横断后用JNJ460处理动物30天，并在超微结构水平上证明了髓鞘和轴突肥大。总体而言，这些数据表明雪旺细胞在亲免素配体的生物学效应中通过在再生过程中影响神经元-神经胶质信号传导发挥重要作用。
亲免素配体再生作用的细胞和分子机制尚未得到充分理解。在此我们表明，JNJ460在DRG模型中的促神经突生成作用取决于神经元和雪旺细胞之间的相互作用。用JNJ460处理纯化的雪旺细胞会改变雪旺细胞基因表达，并促进作用于神经元的因子的产生。这些数据表明雪旺细胞在亲免素配体的作用中发挥重要作用。
