The role of atypical PKCs in sensitization of sensory neurons by NGF

描述(申请人提供)：开创性研究表明，与炎症相关的高敏感性可能部分是由于神经生长因子(NGF)激活了伤害性感觉神经元。我的实验室证明，NGF/BDNF可以通过p75神经营养素受体(P75NTR)激活鞘磷脂信号级联，迅速增加感觉神经元对放电动作电位(AP)的能力。P75NTR激活所导致的细胞机制和下游信号通路尚不清楚。我们的结果表明，p75NTR/神经酰胺激活新的非典型PKC PKM？在增强兴奋性方面起着关键作用，并提示PKM？可能在由于PKM？变得结构性活性而导致的急性敏感化向持续性敏化的转变中起关键作用。拟用成年大鼠背根神经节分离的感觉神经元作为模型系统，探讨p75NTR激活对膜兴奋性的功能影响。从分离的神经元获得的知识将被扩展到探索这些效应分子在调节伤害性行为反应中的作用的研究。这些研究将与哈佛大学的加里·斯特里哈茨博士合作完成。具体目标是：目标1将确定p75NTR及其合成/激活PKM的作用。此外，p75NTR与支架蛋白的相互作用将决定它们调节PKM活性的能力。这项工作将集中在PKM诱导的离子通道的调节及其对神经元兴奋性的调节。在与Gary Strichartz博士的合作中，Aim 2将确定p75NTR-PKM信号级联在完整动物伤害行为调节中的作用。这种多维方法的优势在于，生化和分子技术将建立新的蛋白质-蛋白质关联，电生理学将建立这些关联的功能结果。这些发现将扩展到对完整动物的研究，以了解激活p75NTR导致神经元敏感性增强的机制。有必要对这些事件有一个基本的了解，这样才能设计出更好的化合物和疗法来促进慢性炎症的治疗。 公共卫生相关性：组织损伤和炎症导致损伤部位附近的各种细胞释放化学物质，导致对疼痛刺激的敏感性增加。其中一种关键的化学物质是神经生长因子。在这一应用中提出的研究试图了解神经生长因子激活的细胞内信号通路如何增加神经敏感性，从而导致疼痛反应的增加。

DESCRIPTION (provided by applicant): Seminal studies suggested that the heightened sensitivity associated with inflammation may, in part, result from nerve growth factor (NGF) activation of nociceptive sensory neurons. My laboratory demonstrated that NGF/BDNF can rapidly increase the ability of sensory neurons to fire action potentials (APs) via p75 neurotrophin receptor (p75NTR) activation of the sphingolipid signaling cascade. The cellular mechanisms and downstream signaling pathways resulting from p75NTR activation are poorly understood. Our results demonstrate that p75NTR/ceramide activation of the novel atypical PKC, PKM¿ plays a key role in augmenting excitability and suggest that PKM¿ may have a critical role in the transition of acute to persistent sensitization as a result of PKM¿ becoming constitutively active. Proposed studies will use sensory neurons isolated from DRG of adult rats as a model system to explore the functional impact of p75NTR activation on membrane excitability. Knowledge gained from isolated neurons will be extended to studies exploring the role of these effector molecules in regulating nociceptive behavioral responses. These studies will be done in collaboration with Dr. Gary Strichartz at Harvard University. The specific aims are: Aim 1 will establish the role of p75NTR and its synthesis/activation of PKM¿. Also, p75NTR interaction with scaffolding proteins will determine their ability to regulate the activity of PKM¿ This work will focus on PKM¿-induced modulation of ion channels and their regulation of neuronal excitability. In collaboration with Dr. Gary Strichartz Aim 2 will establish the role of p75NTR-PKM¿ signaling cascades in the regulation of nociceptive behaviors in the intact animal. The strength of this multi-dimensional approach is that biochemical and molecular techniques will establish novel protein-protein associations and electrophysiology will establish the functional outcomes of those associations. These findings will be extended to studies in the intact animal to provide an understanding of the mechanisms whereby activation of p75NTR leads to heightened neuronal sensitivity. A fundamental understanding of these events is necessary so that better compounds and therapies can be designed to facilitate treatment of chronic inflammatory conditions. PUBLIC HEALTH RELEVANCE: Tissue injury and inflammation cause release of chemicals from a variety of cells near the injury site that results in increased sensitivity to painful stimulation. One of those key chemicals is nerve growth factor. Studies proposed in this application seek to understand how intracellular signaling pathways activated by nerve growth factor increase nerve sensitivity and thus lead to the increased pain responses.