Regulation of gastrointestinal neuromuscular function by NIBP/NFkB signaling

描述(申请人提供)：肠道神经系统(ENS)在胃肠道(GI)功能的调节中起着重要作用。成人ENS的形态改变和功能异常与炎症性肠病(IBD)、肠易激综合征(IBS)、胃轻瘫和慢性便秘/腹泻有关。免疫和炎症反应，除了遗传和环境因素外，在这些胃肠道疾病的发病机制中起着关键作用。大多数免疫反应是由核因子kB(NFkB)信号介导的。在目前的资金支持期间，我们证明了NFkB信号在平滑肌中介导炎症诱导的结肠抑制。 平滑的肌肉收缩。在理解来自ENS的NFkB信号如何影响胃肠道疾病方面存在着根本性的差距。长期目标是了解NFkB信号在调节健康和炎症期间胃肠道功能中的作用。这次更新的目的是阐明肠道神经元和星形胶质细胞特异性NFkB信号在调节胃肠道神经肌肉功能中的重要性。核心假设是肠神经NFkB信号是维持胃肠道功能完整性所必需的，而肠神经胶质NFkB信号在正常情况下调节神经功能，但在炎症条件下介导炎症反应。这一假说将通过4个条件性基因敲除或敲除小鼠品系的平行研究来验证，该研究通过在正常和炎症条件下肠道神经元和星形胶质细胞NFkB信号操纵对胃肠收缩的影响进行。在目标1中，我们将分别使用肠内神经元特异性条件基因敲除NIBP或敲除IKK2CA(成分活性形式)小鼠来灭活或过度激活肠神经NFkB信号。在目标2中，我们将使用GFAP-dnIkB？或GFAP-IKK2CA转基因小鼠分别灭活或过度激活肠内星形胶质细胞NFkB信号。在这两个目标中，我们将确定(A)肠神经元和神经胶质细胞的化学编码和形态，(B)神经刺激和激动剂诱导的GI收缩/松弛，以及(C)收缩蛋白和炎症介质在平滑肌肉中的表达模式。这些研究的完成将首次证明神经元NFkB信号在维持ENS功能完整性方面的重要性，以及星形胶质细胞NFkB信号在促进神经胶质和炎症反应中的重要性，这些反应有助于慢性炎症的发生和发展。这一建议在概念上是创新的，包括神经元NIBP调节ENS功能和星形胶质细胞NFkB调节炎症反应，以及新型神经元和星形胶质细胞特异性转基因小鼠的使用。我们的研究将突出ENS NFkB信号的重要性，并为神经胃肠疾病的发病机制提供新的机制。

DESCRIPTION (provided by applicant): The enteric nervous system (ENS) plays an important role in the regulation of gastrointestinal (GI) functions. Morphological changes and functional abnormalities in adult ENS have been associated with inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), gastroparesis and chronic constipation/diarrhea. The immune and inflammatory responses, in addition to genetic and environmental factors, play critical roles in the pathogenesis of these GI diseases. Most of the immune responses are mediated by the signaling of nuclear factor kB (NFkB). During the current funding period, we demonstrated that NFkB signaling in smooth muscle mediates inflammation-induced inhibition of colonic smooth muscle contraction. There is a fundamental gap in understanding how NFkB signaling from the ENS influences GI diseases. The long-term goal is to understand the role of NFkB signaling in the regulation of GI functions in health and during inflammation. The objective of this renewal is to elucidate the importance of enteric neuron- and astroglia-specific NFkB signaling in regulating GI neuromuscular function. The central hypothesis is that enteric neuronal NFkB signaling is required for the maintenance of GI functional integrity while enteric glial NFkB signaling regulates neuronal functions under normal conditions but mediates inflammatory responses under inflamed conditions. This hypothesis will be tested by parallel studies on the effects of enteric neuronal and astroglial NFkB signaling manipulation on GI contractility under normal and inflamed conditions using 4 lines of conditional gene knockout or knockin mice. In aim 1, we will use enteric neuron-specific conditional knockout of NIBP or knockin of IKK2CA (Constitutively Active form) mice to inactivate or overactivate enteric neuronal NFkB signaling, respectively. In aim 2, we will use GFAP-dnIkB? or GFAP-IKK2CA transgenic mice to inactivate or overactivate enteric astroglial NFkB signaling, respectively. In both aims, we will determine changes in (a) chemical coding and morphology of enteric neurons and glial cells, (b) nerve-stimulated and agonist-induced GI contraction/relaxation, and (c) expression patterns of contractile proteins and inflammatory mediators in smooth muscles. Completion of these studies will demonstrate for the first time the importance of neuronal NFkB signaling in the maintenance of ENS functional integrity and astroglial NFkB signaling in facilitating gliotic and inflammatory responses that contribute to the development and progression of chronic inflammation. This proposal is innovative both in concept implicating neuronal NIBP in the regulation of ENS functions and astroglial NFkB in the regulation of inflammation, and in the use of novel neuron- and astroglia-specific transgenic mice. Our studies will highlight the importance of ENS NFkB signaling and provide a novel mechanism for the pathogenesis of neurogastrointestinal disorders.