Targeting alpha7 nAChR for Therapeutic Effects

大脑中有两种主要的尼古丁受体。一种类型的刺激，a7 受体，改善学习，记忆和注意力;可以抑制幻听 精神分裂症;也可能减缓阿尔茨海默病的进展。刺激 另一种尼古丁受体会导致成瘾。因此，α 7烟碱受体 正被十几家制药公司作为药物靶点积极追求。多 这项工作是以我们以前的研究为指导的。例如，直到最近， 没有系统的分析，建立了基本原则，基础的选择性 激活A7。我们现在已经证明，至少有三种不同的结构 可用于修饰核心激动剂结构以实现α 7选择性的基序。许多 A7-选择性药物具有阿那巴aseine或奎宁环作为它们的核心结构，通过 加入大疏水侧基如苯环。精确的化学物质 疏水侧基的结构决定功效和效力。另一个关键 α 7-选择性激动剂彼此之间的区别在于 在短暂的激活阶段之后产生相对稳定的脱敏。的 脱敏是由于与受体的长时间结合，并且脱敏特性 可能会影响其治疗效用。我们已经生成了 各种α 7激动剂如何对接在α 7受体的配体结合结构域中 我们假设这些氨基酸将与 奎宁环类激动剂或阿那巴辛类激动剂的亚苄基上的取代基。 我们将研究氢键和疏水性的潜在重要性 对特异性抗体的结合、门控和脱敏特性的相互作用 受体/配体组合。我们将用定点突变来检验我们的假设， 以及新的α 7-选择性配体， 点对点相互作用，例如，仅能够是H-键供体的试剂，或 受体。野生型和突变型受体将在非洲爪蟾卵母细胞或 瞬时转染的哺乳动物细胞，并且全细胞或单通道电流将 被衡量。我们将使用2型正变构调节剂PNU-120596来测量 特定配体的脱敏特性，克服了固有的开放限制， A7受体的概率，使其单通道电流更适合研究。我们 将进一步操纵开放概率与tkP 3BzPB，一种新的a7选择性 非竞争性拮抗剂，不依赖于使用，高度选择性，有效，缓慢 可逆的我们还将测试从我们的模型中得出的假设， 受体的亚结构域识别三种不同的α 7选择性基序。综合这些 研究将提供重要的进展，导致A7激动剂的未来设计， 药理学特性的优化概况。

There are two main types of nicotine receptors in the brain. Stimulation of one type, the a7 receptor, improves learning, memory, and attention; can suppress the auditory hallucinations of schizophrenics; and may also slow the progression of Alzheimer's disease. Stimulation of the other type of nicotine receptors can cause addiction. Therefore, the a7 nicotinic receptor is being energetically pursued as a drug target by more than a dozen drug companies. Much of that work has been guided by our previous studies. For example, until recently there was no systematic analysis that established the basic principles that underlie the selective activation of a7. We have now demonstrated that there are at least three distinct structural motifs which can be used to modify a core agonist structure to achieve a7 selectivity. Many a7-selective drugs have either anabaseine or quinuclidine as their core structure, modified by the addition of a large hydrophobic side group such as a benzene ring. The precise chemical structure of the hydrophobic side group determines efficacy and potency. Another key feature distinguishing the a7-selective agonists from one another is a varying ability to produce relatively stable desensitization following a transient phase of activation. The desensitization is due to prolonged binding to the receptor, and the desensitizing properties of specific agents are likely to impact their therapeutic utility. We have generated models for how the various a7-agonists dock in the ligand-binding domain of the a7 receptor and have identified amino acids which we hypothesize will have point-to-point interactions with substituents on the benzylidene groups of either quinuclidine or anabaseine-based agonists. We will investigate the potential importance of hydrogen bonding and hydrophobic interactions on the binding, gating, and desensitizing properties of the specific receptor/ligand combinations. We will test our hypotheses with site-directed mutations, as well as with novel a7-selective ligands that will be restricted in their ability to form specific point-to-point interactions, for example, agents which are only able to be H-bond donors or acceptors. Wild-type and mutant receptors will be expressed in either Xenopus oocytes or transiently transfected mammalian cells, and either whole-cell or single-channel currents will be measured. We will use the Type 2 positive allosteric modulator PNU-120596 to measure the desensitizing properties of specific ligands and overcome the intrinsically limited open probability of a7 receptors, making their single-channel currents more amenable to study. We will further manipulate open probability with tkP3BzPB, a novel a7selective noncompetitive antagonist that is use-independent, highly selective, potent, and slowly reversible. We will also test hypotheses derived from our models related to which subdomains of the receptor recognize the three different a7-selectivity motifs. Together these studies will provide important advancements leading to the future design of a7 agonists with optimized profiles of pharmacological properties.