硫化氢和脑内铁调素表达调节

Based on the accumulated information about the relationship among Hydrogen sulphide (H2S) and IL-6/STAT3 and hepcidin expression, we hypothesized that H(2)S might have a key role in the regulation of hepcidin expression in the brain by interfering with IL-6 expression, JAK2 and STAT3 activates, thereby affecting the expression of all relevant iron metabolism proteins Fpn1, TfR1 and DMT1 and also iron contents in the brain under the inflammatory conditions as well as under physiological circumstances. The experiments in this project will be designed to test this hypothesis. ..The specific objectives are to determine 1: the effects of H2S on the IL-6, JAK2, STAT3 and hepcidin as well as three major iron transport proteins Fpn1, TfR1 and DMT 1 in the cortex, substantia nigra and hippocampus and liver of the LPS treated or untreated SD rats as well as the CBS knockout mice and age-matched healthy mice in vivo and in the LPS treated or untreated neurons (co-cultured with or without BV-2 microglia) obtained from the cortex, substantia nigra and hippocampus and liver cells of SD rats in vitro; and 2: the relevant mechanisms involved in the effect of H2S on hepcidin expression by inhibiting or stimulating IL-6, JAK2 or STAT3 activities. ..To our knowledge, the proposed study is the first detailed investigation on whether H2S has a role in brain iron metabolism and homeostasis, particularly in the regulation of hepcidin expression. The questions to be addressed are also key aspects of functions of H2S in the brain and have been untouched previously. The study will provide important insights into the understanding of the relationship between H2S and iron metabolism, and also make important contribution to the knowledge on the mechanisms involved in the expression of hepcidin as well as iron metabolism and homeostasis in the brain. It might also lead to creating a novel therapeutic approach to prevent, ameliorate or disrupt the chain of pathological events occurring in patients with iron associated-neurodegenerative disorders. Prof. Qian ZM (PI) has been working in the area of brain iron metabolism and neurodegenerative disorders for more than 20 years and his laboratory has been considered as a key and active one in the area in the world. The relevant experimental methods and techniques are well established in our laboratories. It is anticipated that the project will take about 48 months to complete. By that time, the major goals should be well-reached.

已证明硫化氢能调控IL-6表达和JAK2及STAT3 磷酸化，也已证明催化硫化氢生成酶CBS和硫化氢在脑内分布广泛, 及IL-6/STAT3信号通路参与脑内调节铁调素表达。根据这些研究，我们假设硫化氢能通过影响IL-6表达、JAK2和STAT3磷酸化来调节脑内铁调素表达，进而影响脑内铁转运蛋白表达及脑铁水平。我们假设这种调节可发生在生理，也可在病理（炎症）情况下。本项目主要目的是验证这些假设。拟进行的研究是国际上第一个详细探讨硫化氢是否能调节脑内铁调素表达，进而影响脑铁平衡的计划。将回答的问题是有关硫化氢生理功能极为重要且从没涉及的方面。研究结果将帮助理解硫化氢和脑铁代谢的关系，增加对铁调素表达、脑铁平衡调控机制的认识；同时，也将为回答‘某些神经退行性疾病脑铁为何异常增高’这一关键病理生理学问题，及为研发防治铁相关神经退行性疾病新药物提供重要信息和基础。

我们的工作回答了项目书中列出的所有关键问题：.1：硫化氢是否在脑铁稳态形成中具有生理作用？.铁缺乏被认为是胱硫醚β-合成酶 (CBS) 缺乏病人智力缺陷和精神障碍形成的原因，而CBS参与硫化氢(H2S)的生成。这导致我们假设：H2S可能在脑铁稳态形成中具有生理作用。我们证实，与CBS+/+小鼠相比，雌雄CBS+/-小鼠大脑皮层CBS表达、铁和铁蛋白含量、转铁蛋白受体1 (TfR1)和运铁蛋白1 (Fpn1)蛋白均显著降低，铁调素 mRNA升高。我们也证实H2S在小鼠皮层(体内)和皮层神经元(体外)中下调铁调素mRNA、IL-6 mRNA和pSTAT3，上调TfR1和Fpn1。这些结果证明H2S对脑铁平衡起有重要作用，H2S经IL-6/pSTAT3/途径控制铁调素，进而调节铁转运蛋白表达和脑铁平衡。(结果待发表)..2：CBS是否是体铁体平衡必需的？.鉴于CBS在肝脏中的高表达，及硫化氢和铁调素的调节系统共用白介素-6通路，我们推测CBS也参与体内铁稳态的调控。我们进一步证实CBS-/-小鼠表现出贫血，血清、肝脏、脾脏和心脏的铁含量显著增加，伴发严重损害肝脏外，表现出血色素沉着病样表型。肝和血清铁调素显著升高。全身性铁超载的一个主要原因是由于抑制红细胞生成而减少铁的使用，这与白细胞介素-6的增加和促红细胞生成素的减少相一致。重要的是，在肝脏中，CBS的缺失导致Nrf2的减少和铁调素的上调，导致铁输出蛋白运铁蛋白1减少，因此肝细胞铁释出下降，造成肝细胞损害。给予突变小鼠CBS过表达腺病毒可部分逆转铁相关表型。这些发现指出了CBS在机体尤其是肝脏的铁稳态中的关键作用。我们的工作显示：除了铁调素通路关键分子的表达异常，与CBS相关的关键分子的表达异常也可能导致血色素沉着症表型(Hepatology 2018;67:21-35)..Novikov A 和 Schwartz RE（Editor of Hepatology）高度评价了本研究，指出：总的来说，研究人员证实了此前未知的CBS通过多种机制调节铁代谢的能力 (HEPATOLOGY 2018;67:21-35)..3： CBS的缺失如何导致红细胞生成的抑制？.我们证实：红细胞生成的抑制主要是由于CBS的缺失抑制了血红素生物合成酶和血红素转运蛋白的表达(Cell Death Dis. 2019;10:708)