Mechanism of 5HT2AR regulation by Egr3

描述（由申请人提供）：即时早期基因早期生长反应3 （EGR3）与精神分裂症有关，并在死后患者的大脑中表达水平降低。我们之前报道过egr3缺陷（-/-）小鼠表现出许多精神分裂症样行为异常。此外，与野生型（WT）相比，它们对氯氮平镇静作用的敏感性降低，这与无法解释的临床观察相一致，即精神分裂症患者对抗精神病药物副作用的耐受性明显高于健康对照组。我们的初步研究表明，Egr3-/-小鼠前额皮质（PFC）中近70%的5 -羟色胺2A受体（5HT2AR）结合丢失可能是这种效应的机制。由于精神分裂症患者也表现出皮层5HT2ARs的表达减少，这表明5HT2ARs的调节可能是Egr3影响精神分裂症风险的一种机制。本研究的目标是全面表征Egr3调控5HT2AR的解剖定位和分子机制，并确定哪些Egr3-/-精神分裂症样行为异常是由5HT2AR缺乏介导的。在目的1中，我们将使用免疫组织化学和原位杂交来解剖定义5HT2AR在Egr3-/-小鼠中的表达。在Aim 2中，我们将使用定量RT-PCR来确定环境胁迫调节Egr3对Htr2a的调节能力。我们将进行染色质免疫沉淀和荧光素酶报告基因检测来验证Egr3通过启动子结合调节Htr2a表达的假设。目的3提出利用病毒介导的5HT2AR过表达来“拯救”Egr3-/-小鼠的精神分裂症样表型，验证5HT2AR缺陷介导这些异常的假设。确定Egr3调节另一种精神分裂症易感基因的机制将增强我们对众多候选基因如何在生物学途径中影响精神分裂症风险的理解。对这一途径的验证应该阐明开发这种毁灭性疾病的新治疗方法的目标。

DESCRIPTION (provided by applicant): The immediate early gene early growth response 3 (EGR3) is associated with schizophrenia and expressed at reduced levels in postmortem patients' brains. We have previously reported that Egr3-deficient (-/-) mice display numerous schizophrenia-like behavioral abnormalities. Moreover, their reduced sensitivity to the sedating effects of clozapine, compared with wildtype (WT) littermates, parallels the unexplained clinical observation that schizophrenia patients display a markedly heightened tolerance to antipsychotic side effects compared to healthy controls. Our preliminary studies reveal that a nearly 70% loss serotonin 2A receptor (5HT2AR) binding in the prefrontal cortex (PFC) of Egr3-/- mice appears to be the mechanism underlying this effect. Since schizophrenia patients also show a decreased expression of cortical 5HT2ARs, this suggests that regulation of 5HT2ARs may be a mechanism through which Egr3 influences schizophrenia risk. The goal of the current proposal is to fully characterize the anatomic localization and molecular mechanism of 5HT2AR regulation by Egr3, and to establish which of the Egr3-/- schizophrenia-like behavioral abnormalities are mediated by 5HT2AR deficiency. In Aim 1 we will use immunohistochemistry and in situ hybridization to anatomically define 5HT2AR expression in Egr3-/- mice. In Aim 2 we will use quantitative RT-PCR to determine the ability of environmental stress to modulate the regulation of Htr2a by Egr3. We will conduct chromatin immunoprecipitation and luciferase reporter assays to test the hypothesis that Egr3 regulates Htr2a expression through promoter binding. Aim 3 proposes to use virus-mediated overexpression of 5HT2AR to "rescue" the schizophrenia-like phenotypes of Egr3-/- mice, testing the hypothesis that the 5HT2AR-deficiency mediates these abnormalities. Identification of mechanisms by which Egr3 regulates another schizophrenia susceptibility gene will enhance our understanding of how numerous candidate genes may act in a biological pathway to influence risk for schizophrenia. Verification of such a pathway should elucidate targets for development of novel treatments for this devastating disorder.