Schaeffer Véronique, Patte-Mensah Christine, Eckert Anne, Mensah-Nyagan Ayikoe G
Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique/Université Louis Pasteur, Strasbourg, France.
J Neurobiol. 2006 Jul;66(8):868-81. doi: 10.1002/neu.20267.
Studies performed with animals suggest neurosteroid involvement in neuroprotection. However in humans, the role of neurosteroidogenesis in the regulation of degenerative processes is unknown. To determine whether cellular factors intervening in degenerative mechanisms may interfere with the process of neurosteroidogenesis in humans, we combined pulse-chase experiments with HPLC and continuous flow scintillation detection to compare neurosteroid production in normal and transfected SH-SY5Y cells with key proteins involved in Alzheimer's disease (AD). Microscope analyses revealed that cell morphology was unchanged in stably transfected SH-SY5Y cells overexpressing human native tau (hTau40), mutant tau (P301L), and wild-type amyloid precursor protein (APPwt) compared to controls. Biochemical investigations showed that hTau40 enhanced progesterone (PROG), 17OHPROG, testosterone, and 3alpha-androstanediol neosynthesis from pregnenolone. In contrast, tau with the pathogenic P301L mutation was devoid of action on neurosteroidogenesis. Overexpression of APPwt inhibited PROG formation, did not affect 17OHPROG and testosterone, but increased 3alpha-androstanediol and estradiol synthesis. Extracellular treatment of control cells with aggregated amyloid peptide mimicked the action of APPwt expression on PROG but not on 3alpha-androstanediol and estradiol production. Moreover, PROG biosynthesis in APPwt cells was up-regulated in the presence of a gamma-secretase inhibitor. Our results provide the first evidence for the regulation of neurosteroid biosynthesis by key proteins involved in the etiology of AD. The data suggest that pathogenic factors may induce neurodegeneration in humans through the reduction of the synthesis of endogenous neuroprotective neurosteroids in nerve cells.
对动物进行的研究表明神经甾体参与神经保护。然而，在人类中，神经甾体生成在退行性过程调节中的作用尚不清楚。为了确定干预退行性机制的细胞因子是否会干扰人类神经甾体生成过程，我们将脉冲追踪实验与高效液相色谱和连续流动闪烁检测相结合，以比较正常和转染的SH-SY5Y细胞中与阿尔茨海默病（AD）相关的关键蛋白的神经甾体生成情况。显微镜分析显示，与对照相比，稳定转染的过表达人类天然tau（hTau40）、突变型tau（P301L）和野生型淀粉样前体蛋白（APPwt）的SH-SY5Y细胞的细胞形态没有变化。生化研究表明，hTau40增强了孕烯醇酮向孕酮（PROG）、17-羟孕酮（17OHPROG）、睾酮和3α-雄烷二醇的新合成。相比之下，具有致病性P301L突变的tau对神经甾体生成没有作用。APPwt的过表达抑制了PROG的形成，不影响17OHPROG和睾酮，但增加了3α-雄烷二醇和雌二醇的合成。用聚集的淀粉样肽对对照细胞进行细胞外处理，模拟了APPwt表达对PROG的作用，但对3α-雄烷二醇和雌二醇的产生没有影响。此外，在γ-分泌酶抑制剂存在的情况下，APPwt细胞中的PROG生物合成上调。我们的结果为AD病因中关键蛋白对神经甾体生物合成的调节提供了首个证据。数据表明，致病因素可能通过减少神经细胞中内源性神经保护神经甾体的合成来诱导人类神经退行性变。
