Department of Neuropathology, University of Bonn Medical Center, Sigmund-Freud Str. 25, Bonn 53105, Germany.
Brain Res. 2013 Mar 7;1499:136-44. doi: 10.1016/j.brainres.2012.12.045. Epub 2013 Jan 16.
Many brain disorders, including epilepsy, migraine and depression, manifest with episodic symptoms that may last for various time intervals. Transient alterations of neuronal function such as related to serotonin homeostasis generally underlie this phenomenon. Several nucleotide polymorphisms (SNPs) in gene promoters associated with these diseases have been described. For obvious reasons, their regulatory roles on gene expression particularly in human brain tissue remain largely enigmatic. The rs6295 G-/C-allelic variant is located in the promoter region of the human HTR1a gene, encoding the G-protein-coupled receptor for 5-hydroxytryptamine (5HT1AR). In addition to reported transcriptional repressor binding, our bioinformatic analyses predicted a reduced binding affinity of the transcription factor (TF) c-Jun for the G-allele. In vitro luciferase transfection assays revealed c-Jun to (a) activate the rs6295 C- significantly stronger than the G-allelic variant and (b) antagonize efficiently the repressive effect of Hes5 on the promoter. The G-allele of rs6295 is known to be associated with aspects of major depression and migraine. In order to address a potential role of rs6295 variants in human brain tissue, we have isolated DNA and mRNA from fresh frozen hippocampal tissue of pharmacoresistant temporal lobe epilepsy (TLE) patients (n=140) after epilepsy surgery for seizure control. We carried out SNP genotyping studies and mRNA analyses in order to determine HTR1a mRNA expression in human hippocampal samples stratified according to the rs6295 allelic variant. The mRNA expression of HTR1a was significantly more abundant in hippocampal mRNA of TLE patients homozygous for the rs6295 C-allele as compared to those with the GG-genotype. These data may point to a novel, i.e., rs6295 allelic variant and c-Jun dependent transcriptional 5HT1AR 'receptoropathy'.
许多脑部疾病，包括癫痫、偏头痛和抑郁症，都表现出间歇性症状，这些症状可能持续不同的时间间隔。神经元功能的短暂改变，如与血清素动态平衡有关的改变，通常是这种现象的基础。已经描述了与这些疾病相关的基因启动子中的几个核苷酸多态性（SNP）。由于显而易见的原因，它们对基因表达的调节作用，特别是在人类脑组织中的作用，在很大程度上仍然是个谜。rs6295 的 G-/C-等位基因变体位于人类 HTR1a 基因的启动子区域，该基因编码 5-羟色胺（5HT1AR）的 G 蛋白偶联受体。除了报道的转录抑制因子结合外，我们的生物信息学分析还预测转录因子（TF）c-Jun 对 G-等位基因的结合亲和力降低。体外荧光素酶转染实验显示，c-Jun 能够（a）显著增强 rs6295 C-等位基因的活性，而不是 G-等位基因变体，（b）有效地拮抗 Hes5 对启动子的抑制作用。rs6295 的 G-等位基因与重度抑郁症和偏头痛的某些方面有关。为了研究 rs6295 变异在人类脑组织中的潜在作用，我们从抗药性颞叶癫痫（TLE）患者（n=140）的新鲜冷冻海马组织中分离了 DNA 和 mRNA，这些患者在癫痫手术后进行了癫痫控制。我们进行了 SNP 基因分型研究和 mRNA 分析，以确定根据 rs6295 等位基因变异对人类海马样本中的 HTR1a mRNA 表达进行分层。与 GG 基因型相比，rs6295 C-等位基因纯合的 TLE 患者海马 mRNA 中 HTR1a 的 mRNA 表达明显更为丰富。这些数据可能指向一种新的、即 rs6295 等位基因和 c-Jun 依赖性转录 5HT1AR“受体病”。
