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

描述（由申请人提供）：开创性的研究表明，与炎症相关的敏感性升高可能部分是由神经生长因子（NGF）激活伤害感觉神经元引起的。我的实验室证明，NGF/BDNF可以通过p75神经营养因子受体（p75NTR）激活鞘脂信号级联，迅速增加感觉神经元发射动作电位（APs）的能力。p75NTR激活的细胞机制和下游信号通路尚不清楚。我们的研究结果表明，p75NTR/神经酰胺激活的新型非典型PKC， PKM¿在增强兴奋性中起关键作用，并表明PKM¿可能在急性致敏到持续致敏的过渡中起关键作用，因为PKM¿变得构成活性。拟建的研究将以成年大鼠DRG分离的感觉神经元为模型系统，探索p75NTR激活对膜兴奋性的功能影响。从孤立的神经元中获得的知识将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。这些研究将与哈佛大学的Gary Strichartz博士合作完成。目标1将确定p75NTR的作用及其对PKM¿的合成/激活。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。这项工作将重点关注PKM诱导的离子通道调节及其对神经元兴奋性的调节。与Gary Strichartz博士合作，Aim 2将建立p75NTR-PKM信号级联在完整动物伤害性行为调节中的作用。这种多维方法的优势在于，生物化学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。这些发现将扩展到完整动物的研究，以提供对p75NTR激活导致神经元敏感性提高的机制的理解。对这些事件有一个基本的了解是必要的，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。

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.