Role of iron in the regulation of PTPs: impact on cell signaling and functions

本研究计划的目的是研究铁在一个名为蛋白酪氨酸磷酸酶（PTP）的酶家族的调节中的含义。ptp通过影响和控制巨噬细胞与激酶的精细平衡，在巨噬细胞（MO）功能的调节中发挥关键作用。通过去磷酸化激酶底物，PTPs可以影响激酶活性水平，从而影响MO功能和先天免疫反应。虽然氧化在PTP的调控中起着重要作用，并且是通过ROS的作用，但我们最近发现铁可以在PTP的调控中发挥关键作用，以单核铁配合物的形式精确地适应PTP的催化口袋，抑制它们的活性。我们认为，这种能力在MO功能调节的背景下，特别是涉及先天免疫反应的能力，可能在控制稳态和异常细胞状况方面发挥关键作用。实际的拨款提案旨在研究这种铁对MO ptp的特异性（目的1），并分析这种铁介导的ptp调节是否发生在体内（目的2）。在Aim 1中，我们建议确定是否所有的MO ptp（经典、DUS ptp和rptp）都类似地受到单核柠檬酸离子的调节，并遵循它们的亚细胞动员到不同的室，以便与参与信号事件的特定底物相互作用，这些信号事件同时调节炎症激动剂对先天免疫的反应。在第2项研究中，上述体外评估的结果将在体内进一步测试，使用特定的ptp抑制剂，接种铁葡聚糖，以及使用生生性铁缺陷小鼠模型。体内铁含量增加或减少的影响将在细胞、分子和先天免疫水平上进行监测。

The goal of this research program is to study the implication of iron in the regulation of a family of enzyme named protein tyrosine phosphatase (PTP). PTPs play a critical role in the regulation of macrophage (MO) functions by influencing and controlling their fine balance with kinases. By dephosphorylating kinase substrates, PTPs can influence the level of kinase activities and consequently the MO functions and innate immune response. Whereas oxidation plays an important role in the regulation of PTPs and this via the action of ROS, we have recently discovered that iron could play a critical in the regulation of PTPs, under the form of a mononuclear dicitrate iron complex precisely fitting itself within PTP's catalytic pocket inhibiting their activity. We believe that such capacity in the context MO function regulations and particuolarly the ones involved in innate immune response could plays a critical role to control homeostatic and abnormal cellular conditions. The actual grant proposal is designed to study the specificity of this iron species toward MO PTPs (Aim 1) and to analyze whether this iron-mediated modulation of PTPs happens in vivo (Aim 2). In Aim 1, we propose to determine whether all MO PTPs (classic, DUS PTPs and RPTPs) are similarly regulated by mononuclear ion-citrate, as well as to follow their sub-cellular mobilization to various compartments in order to interact with specific substrates involved in the signaling events concurring to regulate innate immunity in response to inflammatory agonists. In Aim 2, the findings stemming from in vitro evaluation proposed above, will be further tested in vivo using specific inhibitors for PTPs, inoculation of iron-dextran, as well as to use models with physiologically iron defective mice. Impact of those augmented or reduced availability or iron in vivo will be monitored at cellular, molecular and innate immunity levels. Findings stemming from these studies could permit in a near future to develop new ways to render more resistant animals from industry toward infectious agents by reinforcing their innate immune system, and this by adding newly identified mononuclear dicitrate iron to their diet.