Function of hCG/LH and their receptor in the mammalian nervous system

双能细胞系，PC12，来自大鼠肾上腺嗜铬细胞瘤被用作我们的研究的体外模型。 为研究人绒毛膜促性腺激素（hCG）对PC12细胞分化的影响，将野生型人促黄体生成素/绒毛膜促性腺激素受体（LH/CG-R）转导入PC12细胞，并将稳定表达转基因的亚克隆用于实验。 激活转导LH/CG-R与hCG/LH或表达的组成性激活突变的LH/CG-R在PC12细胞诱导不同的形态和生化变化的神经元分化的特点。 hCG的诱导分化作用具有剂量和时间依赖性。Western blot分析显示，细胞外信号调节激酶（ERK）和p38丝裂原活化蛋白激酶（MAPK）被激活后，hCG处理。抑制剂研究表明ERK和p38 MAPK信号转导通路在分化过程中是不可缺少的。此外，磷脂酶C（PLC）途径部分参与hCG诱导的PC 12分化。这些发现暗示了hCG/LH和LH/CG-R在哺乳动物神经系统的神经发生中的潜在作用。我们进一步研究了hCG在髓鞘形成起始中的可能作用。髓磷脂零蛋白（P0）是周围神经系统髓鞘的主要成分，在髓鞘形成的初始阶段被诱导。hCG与Forskolin联合使用可显著增加体外瞬时表达LH/CG-R的小鼠雪旺细胞系中P0 mRNA的表达。P0蛋白表达的检测正在进行中。提示hCG可能通过诱导P0表达促进髓鞘形成。hCG诱导P0表达的机制可能是通过几种转录因子如krox-20，目前正在研究中。这些研究表明，hCG/LH及其受体参与哺乳动物神经系统的发育和维持。 hCG可能是未来治疗急性神经损伤或神经退行性疾病的潜在再生药物。

The bipotent cell line, PC12, derived from rat adrenal pheochromocytoma was used as an in vitro model for our studies. To examine the effect of human chorionic gonadotropin (hCG) on PC12 differentiation, wild type human luteinizing hormone/chorionic gonadotropin receptor (LH/CG-R) was transduced into PC12 cells and stable transgene-expressing subclones were used for experiments. Activation of transduced LH/CG-R with hCG/LH or expression of a constitutively activated mutated LH/CG-R in PC12 cells induced distinct morphological and biochemical changes characteristic of neuronal differentiation. The differentiation effect of hCG was ligand dose- and time-dependent. Western blot analysis revealed that both the extracellular signal-regulated kinases (ERKs) and p38 mitogen-activated protein kinase (MAPK) were activated after hCG treatment. Inhibitor studies showed both the ERK and p38 MAPK signal transduction pathway were indispensable for the differentiation process. In addition, the Phospholipase C (PLC) pathway was partially involved in hCG induced PC12 differentiation. These findings imply a potential role of hCG/LH and LH/CG-R in the neurogenesis of the mammalian nervous system. We further investigated the possible effect of hCG in the initiation of myelination. Myelin protein zero (P0) is the major component of the myelin sheath of the peripheral nervous system and is induced at the initial phase of myelination. hCG when combined with Forskolin dramatically increased P0 mRNA expression in a mouse Schwann cell line transiently expressing LH/CG-R in vitro. Examination of P0 protein expression is underway. The result suggests hCG may promotes myelination through inducing P0 expression. The mechanism of hCG induced P0 expression could be through several transcription factors such as krox-20 and is under investigation. These studies show that hCG/LH and its receptor participate in the development and maintenance of the mammalian nervous system. hCG could be a potential regeneration drug for future treatment of acute neural injuries or neurodegenerative disorders.