PDF(Pubmed)
Abstract：
Genetic analyses have linked BTBD9 to restless legs syndrome (RLS) and sleep regulation. Btbd9 knockout mice show RLS-like motor restlessness. Previously, we found hyperactivity of cerebellar Purkinje cells (PCs) in Btbd9 knockout mice, which may contribute to the motor restlessness observed. However, underlying mechanisms for PC hyperactivity in Btbd9 knockout mice are unknown. Here, we used dissociated PC recording, brain slice recording and western blot to address this question. Our dissociated recording shows that knockout PCs had increased TEA-sensitive, Ca2+-dependent K+ currents. Applying antagonist to large conductance Ca2+-activated K+ (BK) channels further isolated the increased current as BK current. Consistently, we found increased amplitude of afterhyperpolarization and elevated BK protein levels in the knockout mice. Dissociated recording also shows a decrease in TEA-insensitive, Ca2+-dependent K+ currents. The result is consistent with reduced amplitude of tail currents, mainly composed of small conductance Ca2+-activated K+ (SK) currents, in slice recording. Our results suggest that BK and SK channels may be responsible for the hyperactivity of knockout PCs. Recently, BTBD9 protein was shown to associate with SYNGAP1 protein. We found a decreased cerebellar level of SYNGAP1 in Btbd9 knockout mice. However, Syngap1 heterozygous knockout mice showed nocturnal, instead of diurnal, motor restlessness. Our results suggest that SYNGAP1 deficiency may not contribute directly to the RLS-like motor restlessness observed in Btbd9 knockout mice. Finally, we found that PC-specific Btbd9 knockout mice exhibited deficits in motor coordination and balance similar to Btbd9 knockout mice, suggesting that the motor effect of BTBD9 in PCs is cell-autonomous.
摘要：
遗传分析已将BTBD9与不安腿综合征（RLS）和睡眠调节联系起来。Btbd9敲除小鼠显示RLS样运动躁动。以前,我们发现Btbd9基因敲除小鼠的小脑浦肯野细胞（PC）过度活跃，这可能有助于观察到的运动躁动。然而,Btbd9基因敲除小鼠PC过度活跃的潜在机制尚不清楚.这里,我们用分离的电脑录音，脑片记录和蛋白质印迹来解决这个问题。我们的分离记录显示敲除的PC对TEA的敏感性增加，Ca2+-依赖性K+电流。将拮抗剂应用于大电导Ca2激活的K（BK）通道，进一步将增加的电流隔离为BK电流。始终如一，我们发现基因敲除小鼠的后超极化幅度增加和BK蛋白水平升高。分离的录音也显示了对TEA不敏感的减少，Ca2+-依赖性K+电流。结果与尾电流幅度减小一致，主要由小电导Ca2+激活的K+(SK)电流组成，在切片记录中。我们的结果表明，BK和SK通道可能是敲除PC过度活跃的原因。最近,显示BTBD9蛋白与SYNGAP1蛋白缔合。我们发现Btbd9基因敲除小鼠的小脑SYNGAP1水平降低。然而,Syngap1杂合子敲除小鼠显示夜间，而不是昼夜，电机躁动。我们的结果表明，SYNGAP1缺乏可能不会直接导致Btbd9基因敲除小鼠中观察到的RLS样运动躁动。最后,我们发现PC特异性Btbd9基因敲除小鼠表现出与Btbd9基因敲除小鼠相似的运动协调和平衡缺陷,表明BTBD9在PC中的运动效应是细胞自主的。
