bZIP Repression of Adrenergic Receptor RNA in Neurons

描述（由申请人提供）：肾上腺素能受体（AR）是中枢神经系统（CNS）介导的行为和几种神经功能（包括情绪、记忆、神经内分泌控制和自主神经功能刺激）的重要调节剂。神经递质受体功效的调节和神经元可塑性的控制，如受体脱敏和慢性下调机制所证明的，被认为是抑郁症和抗抑郁药治疗期间发生的大脑适应性过程的一部分。β-AR下调发生在抗抑郁药慢性治疗期间，表明β-肾上腺素能受体（β 1-AR）亚型（大脑中的主要β-AR亚型）的失调可能与抑郁症有关。此外，β-AR激动剂异丙肾上腺素在脑中的中枢给药在大鼠中诱导抗抑郁样作用，并且似乎特异性地涉及β 1-AR亚型。我的实验室已经研究了激动剂诱导后β 1 AR mRNA下调的分子机制，并确定了潜在的转录和转录后控制机制。我们最近在β 1-AR基因中发现了一个转录抑制区，包括相对于翻译起始位点的-396至-367位，并将潜在的抑制分子鉴定为一种新的bZIP样转录因子。这种新的转录因子含有一个基本的DNA结合结构域，包括亮氨酸拉链基序（bZIP样），和磷酸酶基序类似的RNA聚合酶II C-末端结构域（CTD）磷酸酶内所含的。本申请的具体目的是验证bZIP样转录因子作为新生大鼠皮层神经元中β 1-AR表达的阻遏物，并检验该因子是激动剂介导的β 1-AR mRNA下调的决定因素的假设。本提案的主要实验目标是：1）验证bZIP样转录因子在新生大鼠皮层神经元中β 1-AR启动子的阻遏中的相互作用，2）诱变转录因子中的磷酸酶基序和碱性DNA结合结构域，以潜在地产生显性负突变体，3）鉴定在β 1-AR转录抑制过程中形成的bZIP样反式激活因子复合物中的其他潜在配偶体，和4）确定bZIP样转录因子在激动剂介导的β 1-AR mRNA下调的分子机制中的作用。调控新生大鼠皮层神经元使用蜕皮激素诱导的表达和RNA干扰系统。这些信息可能为大脑中β-AR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见解。此R21资助申请是根据PA-03-107（“NIH探索/发展资助[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").