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

本研究的目的是研究铁在蛋白酪氨酸磷酸酶(PTP)家族的调控中的意义。PTPs通过影响和控制巨噬细胞(MO)与激酶的精细平衡，在巨噬细胞(MO)功能的调节中发挥重要作用。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PTPs的调节中起着重要的作用，并且这是通过ROS的作用，我们最近发现铁在PTPs的调节中发挥关键作用，以单核二柠檬酸铁络合物的形式精确地适合自己在PTP的催化口袋中抑制它们的活性。我们认为，在MO功能调节的背景下，这种能力，特别是参与先天性免疫反应的能力，可能在控制体内平衡和异常细胞状况方面发挥关键作用。实际的赠款提案旨在研究这种铁物种对MO PTPs的特异性(目标1)，并分析这种铁介导的PTPs的调节是否在体内发生(目标2)。在目标1中，我们建议确定是否所有的MO PTPs(Classic，DUS PTPs和RPTPs)都受到单核离子柠檬酸盐的类似调节，并跟随它们的亚细胞动员到不同的隔室，以便与参与信号事件的特定底物相互作用，从而调节对炎症激动剂的天然免疫。在目标2中，来自上述体外评估的结果将使用PTPs的特定抑制剂、接种葡聚糖铁以及使用生理性铁缺陷小鼠的模型进行进一步的体内测试。将在细胞、分子和先天免疫水平上监测体内铁的有效性增加或减少的影响。

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.