Investigation into pathology of CAG repeat diseases and development of therapies

脊髓延髓肌萎缩症是一种遗传性运动神经元疾病。SBMA的分子基础是雄激素受体（AR）基因中编码多聚谷氨酰胺（polyQ）序列的三核苷酸CAG重复序列的扩增。我们产生了表达全长人AR的转基因小鼠模型，该全长人AR含有在巨细胞病毒增强子和鸡β-肌动蛋白启动子控制下的24或97个CAG重复序列（AR-97 Q小鼠）。首先，我们阉割雄性AR-97 Q小鼠。去势雄性动物的运动功能、体重、寿命和突变体AR的核积累都有显著改善。另一方面，睾酮给药导致其症状显著加重，并增强了雌性小鼠中突变体AR的核蓄积。在大多数polyQ疾病中，突变蛋白与扩展的polyQ束的核积累可能在诱导神经元细胞功能障碍和变性中是重要的。阉割前的男性 ...更多信息 通过降低睾酮水平来排出突变体AR的核积聚，并改善其运动功能。同样，使用亮丙瑞林（一种可减少睾丸睾酮释放的LHRH类似物）的睾酮阻断治疗显示，运动功能和突变体AR的核蓄积显著改善。在这些结果的基础上，我们开始了使用亮丙瑞林的双盲临床试验。接下来，我们将AR-97 Q小鼠与过表达人HSP 70诱导型的小鼠杂交。HSP 70的高表达可明显改善AR-97 Q小鼠的运动功能。在双转基因小鼠中，核突变体AR的积累，特别是大的复杂形式，显着减少。HSP 70过表达也降低了单体突变体AR的量，表明突变体AR的降解增强。这些结果表明，HSP 70过表达改善SBMA表型小鼠通过减少核定位的突变体AR，这可能是由于增强突变体AR降解。少

Spinal and bulbar muscular atrophy (SBMA) is an inherited motor neuron disease. The molecular basis of SBMA is the expansion of a trinucleotide CAG repeat, which encodes the polyglutamine (polyQ) tract, in the androgen receptor (AR) gene. We generated transgenic mouse model expressing the full-length human AR containing either 24 or 97 CAG repeats under the control of a cytomegalovirus enhancer and a chicken β-actin promoter (AR-97Q mice). First, we castrated male AR-97Q mice. Castrated males showed profound improvement of their motor function, body weight, lifespan and nuclear accumulation of the mutant AR. On the other hand, testosterone administration caused a significant aggravation of their symptoms and enhanced nuclear accumulation of the mutant AR in female mice. Nuclear accumulation of the mutant protein with an expended polyQ tract is likely to be important in inducing neuronal cell dysfunction and degeneration in the majority of the polyQ diseases. Castration of the males pre … More vented the nuclear accumulation of the mutant AR by reducing the testosterone level, and improved their motor function. Similarly, testosterone blockade therapy, using leuprorelin, a LHRH analogue which reduces testosterone release from the testis, showed a marked amelioration of motor function and nuclear accumulation of the mutant AR. On the basis of these results, we started the double-blind clinical trial using leuprorelin.Next, we cross-bred AR-97Q mice with mice over-expressing the inducible form of human HSP70. High expression of HSP70 markedly ameliorated motor function of AR-97Q mice. In double transgenic mice, nuclear mutant AR accumulation, particularly that of the large complex form, was significantly reduced. Monomeric mutant AR was also reduced in amount by HSP70 over-expression, suggesting the enhanced degradation of mutant AR. These findings suggest that HSP70 over-expression ameliorates SBMA phenotypes in mice by reducing nuclear-localized mutant AR, which probably due to enhanced mutant AR degradation. Less