Mechanisms of TNFa Enhancement of Nicotinic Receptor Upregulation

性状（由申请方提供）：尼古丁通过与神经元烟碱乙酰胆碱受体（nAChR）相互作用对细胞功能产生影响。其中一些受体，特别是那些组成？四个？2亚基，通过上调过程对持续的配体暴露做出反应，如高亲和力尼古丁结合位点密度的大幅增加所定义的。上调的生理后果与许多不同的过程有关，从成瘾到导致阿尔茨海默病早期阶段的病理生理过程。一个令人兴奋的和相对较新的作用nAChR正在出现与促炎细胞因子的相互作用。事实上，尼古丁的抗炎特性，通过各种nAChR起作用，现在被广泛报道影响许多炎症病因学疾病。然而，相对知之甚少的机制控制炎症：nAChR的相互作用。该提案的总体目标是定义调节关键促炎细胞因子和nAChR亚型的定义组合之间的相互作用的细胞内机制。具体目标1.假设：TNF？- p38 MAPK通路和/或IL-1的激活？激活PKA通路增强？四个？2的表达，并且这些被涉及PI 3 K/Akt信号传导的途径拮抗。在这个目标中，我们将追求的TNF？和/或IL-1？增强尼古丁介导的nAChR上调？？四个？2.具体目标2.假设：直接磷酸化？4和其他nAChR亚单位的存在下修改的促炎细胞因子信号介导增强上调？四个？2.这一目标将确定的影响：1）修改PKA磷酸化位点？4; 2）引入（或删除）其他nAChR（具体？7或？5）;和3）确定TNF？还是IL-1？细胞内信号传导导致增强？四个？2在培养的神经元中上调。具体目标3.假设：中枢神经系统细胞（如神经元和小胶质细胞（Mg））之间的相互作用指导了总体炎症反应的结果：nAChR反应。神经元和小胶质细胞将以不同的比例共培养，以解剖旁分泌，自分泌或非分泌相互作用在调节TNF？IL-1？介导的增强？四个？2-在混合细胞系统中上调。 公共卫生相关性：我们有兴趣了解尼古丁和炎症之间的相互作用。我们将确定细胞因子用于促进或抑制烟碱受体上调的信号转导途径。两种主要的细胞因子，肿瘤坏死因子α（TNF？）白细胞介素-1？(IL-1?)增强尼古丁诱导的高亲和力尼古丁受体上调称为nAChR？四个？2.上调反应与成瘾行为和多种大脑病理学如阿尔茨海默病相关。了解炎症系统和对尼古丁的反应如何相互作用将影响我们如何用治疗药物解决这些问题。

DESCRIPTION (provided by applicant): Nicotine imparts its effects on cellular function through interaction with neuronal nicotinic acetylcholine receptors (nAChR). Some of these receptors, especially those composed of ?4?2 subunits, respond to sustained ligand exposure through the process of upregulation as defined by a substantial increase in the density of high affinity nicotine binding sites. The physiological consequences of upregulation have been linked to many diverse processes ranging from addiction to pathophysiological processes contributing to early phases of Alzheimer's disease. An exciting and relatively new role for nAChRs is emerging with regard to the interaction with pro-inflammatory cytokines. In fact, the anti-inflammatory properties of nicotine, acting through various nAChRs, is now widely reported to influence many diseases of inflammatory etiology. However, relatively little is known about the mechanisms controlling the inflammatory:nAChR interaction. The overall goal of this proposal is to define intracellular mechanisms that regulate the interactions between key pro-inflammatory cytokines and defined combinations of nAChR subtypes. SPECIFIC AIM 1. Hypothesis: TNF?-activation of the p38MAPK pathway and/or IL-1? activation of PKA pathways enhance ?4?2 expression and these are antagonized by pathways involving PI3K/Akt signaling. In this Aim we will pursue the definition of intracellular pathways initiated by TNF? and/or IL-1? to enhance nicotine-mediated upregulation of nAChR??4?2. SPECIFIC AIM 2. Hypothesis: Direct phosphorylation of ?4 and the presence of other nAChR subunits modify the pro-inflammatory cytokine signals mediating enhanced upregulation of ?4?2. This Aim will determine the impact of: 1) modifying PKA phosphorylation sites in ?4; 2) introducing (or deleting) other nAChRs (specifically ?7 or ?5); and 3) determining effects of TNF? or IL-1? intracellular signaling leading to enhanced ?4?2 upregulation in cultured neurons. SPECIFIC AIM 3. Hypothesis: Interactions between cells of the CNS such as neurons and microglia (Mg) direct the outcome of the overall inflammatory:nAChR response. Neurons and microglia will be co-cultured in different ratios to dissect the relative contribution of paracrine, autocrine or juxtacrine interactions in modulating the TNF? and IL-1?-mediated enhancement of ?4?2-upregulation in a mixed cell system. PUBLIC HEALTH RELEVANCE: We are interested in understanding the interaction between nicotine and inflammation. We will determine the signal transduction pathways cytokines use to promote or inhibit enhanced upregulation of nicotinic receptors. Two major cytokines, tumor necrosis factor alpha (TNF?) and interleukin-1? (IL-1?) enhance nicotine-induced upregulation of the high affinity nicotine receptor termed nAChR?4?2. The upregulation response is correlated with addiction behaviors and multiple pathologies of the brain such as Alzheimer's disease. Understanding how the inflammatory system and response to nicotine interact will impact upon how we approach these problems with therapeutic agents.