bZIP Repression of Adrenergic Receptor RNA in Neurons

描述(申请人提供)：肾上腺素能受体(AR)是中枢神经系统(CNS)介导的行为和多种神经功能的重要调节因子，包括情绪、记忆、神经内分泌控制和自主神经功能的刺激。神经递质受体效应的调节和神经元可塑性的控制，在受体脱敏和慢性下调机制中得到证实，被认为是抑郁症和抗抑郁药物治疗期间大脑适应过程的一部分。β-AR的下调发生在抗抑郁药物的慢性治疗过程中，这表明大脑中占主导地位的β-肾上腺素能受体(Beta1-AR)亚型的调节失调可能与抑郁症有关。此外，中枢给药(β-AR激动剂异丙肾上腺素)在大鼠脑内诱导抗抑郁药样效应，并似乎特异性地涉及(β1-AR亚型。我的实验室已经研究了激动剂诱导后β1AR mRNA下调的分子机制，并确定了潜在的转录和转录后调控机制。我们最近在Beta1-AR基因中发现了一个转录抑制区，相对于翻译起始点有-396到-367个位置，并确定这个潜在的抑制分子是一个新的bZIP样转录因子。这个新的转录因子含有一个基本的DNA结合域，包括一个亮氨酸拉链基序(bZIP-like)和一个类似于RNA聚合酶II C末端结构域(CTD)磷酸酶的磷酸酶基序。本应用的具体目的是验证bZIP样转录因子作为新生大鼠皮质神经元β1-AR表达的抑制因子，并验证该因子是激动剂介导的β1-AR mRNAs下调的决定因素的假设。该建议的主要实验目标是：1)验证bZIP样转录因子在抑制新生大鼠皮质神经元Beta1-AR启动子表达中的相互作用；2)突变转录因子中的磷酸酶基序和基本DNA结合结构域，以获得潜在的负性突变体；3)确定在Beta1-AR转录抑制过程中形成的bZIP样反式激活复合体中的其他潜在合作伙伴；以及4)使用econe诱导表达失调和RNA干扰系统，确定bZIP样转录因子在激动剂介导的新生大鼠皮质神经元Beta1-AR mRNA下调的分子机制中所扮演的角色。这一信息可能为大脑中β-受体的调节以及这些神经递质受体在抑郁症中的潜在作用提供重要的见解。本R21拨款申请是根据PA-03-107(“NIH探索/发展拨款[R21]计划”)提交的。

DESCRIPTION (provided by applicant): Adrenergic receptors (ARs) serve as important regulators of central nervous system- (CNS-) mediated behavior and several neural functions, including mood, memory, neuroendocrine control, and stimulation of autonomic function. Regulation of neurotransmitter receptor efficacy and control of neuronal plasticity, as evidenced in receptor desensitization and chronic down-regulation mechanisms, are recognized as part of the adaptive process in the brain that occurs during depression and antidepressant therapy. Beta-AR down-regulation occurs during chronic treatment with antidepressants, suggesting that the dysregulation of the beta`-adrenergic receptor (beta1-AR) subtype, the predominant (beta-AR subtype in the brain, may be associated with depression. Furthermore, the central administration of (beta-AR agonist isoproterenol in the brain induces antidepressant-like effects in the rat, and appears to specifically involve the (beta1-AR subtype. My laboratory has examined the molecular mechanisms underlying beta1AR mRNA down-regulation following agonist induction, and have identified potential transcriptional and post-transcriptional control mechanisms. We have recently identified a transcriptional represser region in the beta1-AR gene, encompassing positions -396 to -367 relative to the translational start site, and have identified the potential represser molecule as a novel bZIP-like transcription factor. This novel transcription factor contains a basic DNA-binding domain, including a leucine zipper motif (bZIP-like), and a phosphatase motif similar to those contained within the RNA polymerase II C-terminal domain (CTD) phosphatases. The specific aims of this application are to validate the bZIP-like transcription factor as a represser of beta1-AR expression in neonatal rat cortical neurons and to test the hypothesis that this factor is a determinant in the agonist-mediated down-regulation of beta1-AR mRNAs. The primary experimental objectives of this proposal are: 1) to verify interaction of the bZIP-like transcription factor in the repression of the beta1-AR promoter in neonatal rat cortical neurons, 2) to mutagenize the phosphatase motif and basic DNA-binding domain in the transcription factor for potential development of a dominant negative mutant, 3) to identify other potential partners in the bZIP-like transactivator complex formed during beta1-AR transcriptional repression, and 4) to determine the role of the bZIP-like transcription factor in molecular mechanisms underlying agonist-mediated beta1-AR mRNA down-regulation in neonatal rat cortical neurons using both ecdysone-inducible expression and RNA interference systems. This information may provide important insights in the regulation of beta-ARs in the brain and the potential role of these neurotransmitter receptors in depression. This R21 grant application is submitted under PA-03-107 ("NIH Exploratory/Developmental Grant [R21] Program").