Departments of Anatomy/Neurobiology, Pediatrics, and Neurology, University of California-Irvine, Irvine, CA, USA.
Ann Neurol. 2011 Sep;70(3):454-64. doi: 10.1002/ana.22479.
Enduring, abnormal expression and function of the ion channel hyperpolarization-activated cyclic adenosine monophosphate gated channel type 1 (HCN1) occurs in temporal lobe epilepsy (TLE). We examined the underlying mechanisms, and investigated whether interfering with these mechanisms could modify disease course.
Experimental TLE was provoked by kainic acid-induced status epilepticus (SE). HCN1 channel repression was examined at mRNA, protein, and functional levels. Chromatin immunoprecipitation was employed to identify the transcriptional mechanism of repressed HCN1 expression, and the basis for their endurance. Physical interaction of the repressor, NRSF, was abolished using decoy oligodeoxynucleotides (ODNs). Video/electroencephalographic recordings were performed to assess the onset and initial pattern of spontaneous seizures.
Levels of NRSF and its physical binding to the Hcn1 gene were augmented after SE, resulting in repression of HCN1 expression and HCN1-mediated currents (I(h) ), and reduced I(h) -dependent resonance in hippocampal CA1 pyramidal cell dendrites. Chromatin changes typical of enduring, epigenetic gene repression were apparent at the Hcn1 gene within a week after SE. Administration of decoy ODNs comprising the NRSF DNA-binding sequence (neuron restrictive silencer element [NRSE]), in vitro and in vivo, reduced NRSF binding to Hcn1, prevented its repression, and restored I(h) function. In vivo, decoy NRSE ODN treatment restored theta rhythm and altered the initial pattern of spontaneous seizures.
Acquired HCN1 channelopathy derives from NRSF-mediated transcriptional repression that endures via chromatin modification and may provide insight into the mechanisms of a number of channelopathies that coexist with, and may contribute to, the conversion of a normal brain into an epileptic one.
在颞叶癫痫（TLE）中，离子通道超极化激活环核苷酸门控通道 1（HCN1）持续异常表达和功能。我们研究了潜在的机制，并探讨了干扰这些机制是否可以改变疾病进程。
通过红藻氨酸诱导的癫痫持续状态（SE）引起实验性 TLE。在 mRNA、蛋白质和功能水平上检查 HCN1 通道抑制。采用染色质免疫沉淀技术鉴定 HCN1 表达受抑制的转录机制及其持续存在的基础。使用诱饵寡脱氧核苷酸（ODNs）消除抑制剂 NRSF 的物理相互作用。进行视频/脑电图记录以评估自发性癫痫发作的发作和初始模式。
SE 后 NRSF 及其与 Hcn1 基因的物理结合水平增加，导致 HCN1 表达和 HCN1 介导的电流（I(h)）受到抑制，以及海马 CA1 锥体神经元树突中 I(h)依赖性共振减少。SE 后一周内，Hcn1 基因中出现了典型的持久表观遗传基因抑制染色质变化。体外和体内给予包含 NRSF DNA 结合序列（神经元限制沉默元件[NRSE]）的诱饵 ODN，可减少 NRSF 与 Hcn1 的结合，防止其抑制，并恢复 I(h)功能。体内，诱饵 NRSE ODN 治疗可恢复θ节律并改变自发性癫痫发作的初始模式。
获得性 HCN1 通道病源自 NRSF 介导的转录抑制，通过染色质修饰持续存在，这可能为许多与正常大脑转化为癫痫大脑有关并可能有助于这种转化的通道病的机制提供了新的认识。
