Transciption-independent Signaling by IL1 in Neurons

描述（由申请方提供）：促炎细胞因子白细胞介素1-β（IL-1 β）在体内和体外抑制下丘脑中温敏感神经元的活性，该作用似乎是其作为热原（发热诱导剂）活性的基础。抑制发生在IL-1 β应用后的100-300毫秒内，信号传导机制尚不清楚。这种作用的速度表明，NF κ B介导的转录变化，这是研究最多的IL-1 β作用的信号传导途径，不太可能是IL-1 β这种快速作用的原因。本研究以温度敏感的下丘脑神经元为模型，探讨IL-1 β快速信号转导的分子机制。我们将使用生物化学和分子生物学，细胞，电生理学和体内遥测方法来确定第二信使系统参与下丘脑温敏神经元的快速IL-1 β效应，随后对发热反应。我们有初步的数据表明，IL-1 β通过1型IL-1受体刺激鞘磷脂酶活性可能参与了IL-1 β的快速信号传导。鞘磷脂酶产物C2神经酰胺的细胞穿透类似物引起快速发热反应，使人想起IL-1 β诱导发热的早期阶段。体外C2神经酰胺激活下丘脑神经元中ERK的磷酸化，类似于IL-1 β。我们将检验IL-1 β的快速效应涉及神经酰胺介导的蛋白磷酸化依赖性神经元活性变化以及神经酰胺作为IL-1 β快速非转录依赖性作用的第二信使的假设。由于IL-1受体在下丘脑中组成性表达，确定其作用的分子机制将有助于更好地理解IL-1 β在下丘脑中的神经元效应，在下丘脑中，IL-1 β调节HPA轴、温度设定点和发热反应

DESCRIPTION (provided by applicant): The pro-inflammatory cytokine interleukin 1-Beta (IL-1Beta) suppresses the activity of warm sensitive neurons in the hypothalamus in vivo and in vitro, and this action appears to underlie its activity as a pyrogen (fever-inducing agent). The suppression occurs within 100-300 milliseconds after application of IL-1Beta, and the signaling mechanisms are not known. The speed of the effects suggest that NFKB mediated transcriptional changes, which are the most studied signaling pathways for IL-1Beta action, are not likely to be responsible for this rapid action of IL-1Beta. The goal of this study is to identify the molecular mechanisms of rapid IL-1Beta signaling, using thermosensitive hypothalamic neurons as a model. We will use biochemical and molecular biological, cellular, electrophysiological, and in vivo telemetrical approaches to identify the second messenger system involved in the rapid IL-1Beta effects on hypothalamic warm-sensitive neurons, and subsequently on the fever response. We have preliminary data indicating that IL-1Beta stimulation of sphingomyelinase activity through the type 1 IL-1 receptor may be involved in the rapid signaling of IL-1Beta. The cell penetrating analog of the sphingomyelinase product C2 ceramide causes rapid fever response reminiscent of the early phase of IL-1Beta induced fever. In vitro C2 ceramide activates phosphorylation of ERK in hypothalamic neurons similar to IL-1Beta. We will test the hypothesis that rapid effects of IL-1Beta involve ceramide-mediated protein phosphorylation-dependent changes in neuronal activity and that ceramide acts as second messenger of the rapid non-transcription dependent actions of IL-1Beta. Since IL-1 receptors are constitutively expressed in the hypothalamus, defining their molecular mechanisms of action will contribute to a better understanding of the neuronal effects of IL-1Beta in the hypothalamus, where it regulates the HPA axis, the temperature setpoint, and fever response