A ROLE FOR DYSTONIA-ASSOCIATED GENES IN SPINAL GABAERGIC INTERNEURON CIRCUITRY

Spinal interneurons are critical modulators of locomotor circuit function. In the dorsal spinal cord, a set of interneurons called GABApre presynaptically inhibits proprioceptive sensory afferent terminals, thus negatively regulating sensory-motor signaling. While deficits in presynaptic inhibition have been inferred in human locomotor diseases, including dystonia, it remains unknown whether GABApre circuit components are altered in these conditions. In this study, we use developmental timing to show that GABApre neurons are a late Ptf1a-expressing subclass and localize to the intermediate spinal cord. Using a microarray screen to identify genes expressed in this intermediate population, we find the kelch-like family member Klhl14, implicated in dystonia through its direct binding with torsion-dystonia related protein Tor1a. Furthermore, in Tor1a mutant mice in which Klhl14 and Tor1a binding is disrupted (Dyt1deltaE), GABApre-sensory afferent synapse formation is impaired. Our findings suggest a potential contribution of GABApre neurons to the deficits in presynaptic inhibition observed in dystonia. 9 total samples were analyzed: three replicates (1, 2, and 3) with samples from 3 regions of the spinal cord (D, I, and V) each.脊髓中间神经元（spinal interneurons）是运动环路功能的关键调控因子。在脊髓背侧区域，一类被命名为GABApre的中间神经元可对本体感觉传入神经末梢施加突触前抑制，进而负向调控感觉运动信号传导。尽管已有研究推断人类运动疾病（如肌张力障碍）中存在突触前抑制缺陷，但目前尚不清楚此类疾病中GABApre环路组分是否发生改变。 本研究通过发育时序分析证实，GABApre神经元属于晚期表达Ptf1a的神经元亚类，定位于脊髓中间区域。 我们通过基因芯片（microarray）筛选鉴定该中间区域群体的表达基因时，发现了Kelch样家族成员Klhl14，该蛋白可通过与肌张力障碍相关蛋白Tor1a直接结合而与肌张力障碍发病相关。 此外，在Klhl14与Tor1a结合受到破坏的Tor1a突变小鼠（Dyt1deltaE）中，GABApre与感觉传入神经的突触形成过程受到损伤。 本研究结果提示，GABApre神经元可能与肌张力障碍中观察到的突触前抑制缺陷存在潜在关联。 本研究共分析9份样本：取自脊髓3个区域（背侧D、中间I、腹侧V）的样本各设置3次生物学重复（编号1、2、3）。