Department of Pediatrics, Center for Molecular Genetics, University of California, San Diego School of Medicine, La Jolla, California 92093-0634, USA.
Mol Ther. 2010 Jan;18(1):54-62. doi: 10.1038/mt.2009.178. Epub 2009 Aug 11.
Neuronal transcription factors play vital roles in the specification and development of neurons, including dopaminergic (DA) neurons. Mutations in the gene encoding the purine biosynthetic enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT) cause the resulting intractable and largely untreatable neurological impairment of Lesch-Nyhan disease (LND). The disorder is associated with a defect in basal ganglia DA pathways. The mechanisms connecting the purine metabolic defect and the central nervous system (CNS) phenotype are poorly understood but have been presumed to reflect a developmental defect of DA neurons. We have examined the effect of HPRT deficiency on the differentiation of neurons in the well-established human (NT2) embryonic carcinoma neurogenesis model. We have used a retrovirus expressing a small hairpin RNA (shRNA) to knock down HPRT gene expression and have examined the expression of a number of transcription factors essential for neuronal differentiation and marker genes involved in DA biosynthetic pathway. HPRT-deficient NT2 cells demonstrate aberrant expression of several transcription factors and DA markers. Although differentiated HPRT-deficient neurons also demonstrate a striking deficit in neurite outgrowth during differentiation, resulting neurons demonstrate wild-type electrophysiological properties. These results represent direct experimental evidence for aberrant neurogenesis in HPRT deficiency and suggest developmental roles for other housekeeping genes in neurodevelopmental disease.
神经元转录因子在神经元的特化和发育中发挥着重要作用，包括多巴胺能（DA）神经元。嘌呤生物合成酶次黄嘌呤-鸟嘌呤磷酸核糖转移酶（HPRT）基因编码突变导致难以治疗且基本无法治疗的莱希-尼汉病（LND）。该疾病与基底神经节 DA 通路的缺陷有关。嘌呤代谢缺陷与中枢神经系统（CNS）表型之间的联系机制尚未完全了解，但据推测反映了 DA 神经元的发育缺陷。我们已经检查了 HPRT 缺乏对已建立的人类（NT2）胚胎癌细胞神经发生模型中神经元分化的影响。我们使用表达短发夹 RNA（shRNA）的逆转录病毒来敲低 HPRT 基因表达，并检查了许多对神经元分化至关重要的转录因子和参与 DA 生物合成途径的标记基因的表达。HPRT 缺陷型 NT2 细胞表现出几种转录因子和 DA 标记物的异常表达。尽管分化的 HPRT 缺陷型神经元在分化过程中也表现出突起生长的明显缺陷，但这些神经元表现出野生型的电生理特性。这些结果代表了 HPRT 缺乏时异常神经发生的直接实验证据，并表明其他管家基因在神经发育疾病中的发育作用。
