Neurogenetics Branch, NINDS, NIH, Bethesda, MD, USA.
J Neurosci Res. 2010 Aug 1;88(10):2207-16. doi: 10.1002/jnr.22389.
Expanded polyglutamine tracts cause neurodegeneration through a toxic gain-of-function mechanism. Generation of inclusions is a common feature of polyglutamine diseases and other protein misfolding disorders. Inclusion formation is likely to be a defensive response of the cell to the presence of unfolded protein. Recently, the compound B2 has been shown to increase inclusion formation and decrease toxicity of polyglutamine-expanded huntingtin in cultured cells. We explored the effect of B2 on spinal and bulbar muscular atrophy (SBMA). SBMA is caused by expansion of polyglutamine in the androgen receptor (AR) and is characterized by the loss of motor neurons in the brainstem and spinal cord. We found that B2 increases the deposition of mutant AR into nuclear inclusions, without altering the ligand-induced aggregation, expression, or subcellular distribution of the mutant protein. The effect of B2 on inclusions was associated with a decrease in AR transactivation function. We show that B2 reduces mutant AR toxicity in cell and fly models of SBMA, further supporting the idea that accumulation of polyglutamine-expanded protein into inclusions is protective. Our findings suggest B2 as a novel approach to therapy for SBMA.
扩展的多聚谷氨酰胺链通过毒性获得性功能机制导致神经退行性变。包涵体的生成是多聚谷氨酰胺疾病和其他蛋白质错误折叠疾病的共同特征。包涵体的形成可能是细胞对未折叠蛋白质存在的防御反应。最近，化合物 B2 已被证明可增加培养细胞中多聚谷氨酰胺扩展的 huntingtin 的包涵体形成并降低其毒性。我们研究了 B2 对脊髓延髓肌萎缩症（SBMA）的影响。SBMA 是由雄激素受体（AR）中多聚谷氨酰胺的扩展引起的，其特征是脑桥和脊髓中的运动神经元丧失。我们发现 B2 增加了突变型 AR 沉积到核包涵体中，而不改变配体诱导的突变蛋白聚集、表达或亚细胞分布。B2 对包涵体的影响与 AR 转录激活功能的降低有关。我们表明 B2 降低了 SBMA 细胞和果蝇模型中突变型 AR 的毒性，进一步支持了将多聚谷氨酰胺扩展蛋白积累到包涵体中具有保护作用的观点。我们的发现表明 B2 是治疗 SBMA 的一种新方法。
