IRAK-M is an inhibitor of Toll-like receptor signaling that acts by re-directing IRAK-4 activity to TAK1 independent NF-κB activation and by inhibition of IRAK-1/IRAK-2 activity. IRAK-M is expressed in monocytes/macrophages and lung epithelial cells. Lack of IRAK-M in mice greatly improves the resistance to nosocomial pneumonia and lung tumors, which entices IRAK-M as a potential therapeutic target. IRAK-M consists of an N-terminal death domain (DD), a dysfunctional kinase domain and unstructured C-terminal domain. Little is known however on IRAK-M's structure-function relationships.

RESULTS:

Since death domains provide the important interactions of IRAK-1, IRAK-2 and IRAK-4 molecules, we generated a 3D structure model of the human IRAK-M-DD (residues C5-G119) to guide mutagenesis studies and predict protein-protein interaction points. First we identified the DD residues involved in the endogenous capacity of IRAK-M to activate NF-κB that is displayed upon overexpression in 293T cells. W74 and R97, at distinct interfaces of the IRAK-M-DD, were crucial for this endogenous NF-κB activating capacity, as well as the C-terminal domain (S445-E596) of IRAK-M. Resulting anti-inflammatory A20 and pro-inflammatory IL-8 transcription in 293T cells was W74 dependent, while IL-8 protein expression was dependent on R97 and the TRAF6 binding motif at P478. The IRAK-M-DD W74 and R97 binding interfaces are predicted to interact with opposite sides of IRAK-4-DD's. Secondly we identified DD residues important for the inhibitory action of IRAK-M by stable overexpression of mutants in THP-1 macrophages and H292 lung epithelial cells. IRAK-M inhibited TLR2/4-mediated cytokine production in macrophages in a manner that is largely dependent on W74. R97 was not involved in inhibition of TNF production but was engaged in IL-6 down-regulation by IRAK-M. Protein-interactive residues D19-A23, located in between W74 and R97, were also observed to be crucial for inhibition of TLR2/4 mediated cytokine induction in macrophages. Remarkably, IRAK-M inhibited TLR5 mediated IL-8 production by lung epithelial cells independent of W74 and R97, but dependent on D19-A23 and R70, two surface-exposed regions that harbor predicted IRAK-2-DD interaction points of IRAK-M.

CONCLUSION:

IRAK-M employs alternate residues of its DD to inhibit the different inflammatory mediators induced by varying TLRs and cells.

2014-02-01·Plant signaling & behavior4区 · 生物学

A probable crosstalk between Ca⁺², reactive oxygen species accumulation and scavenging mechanisms and modulation of protein kinase C activity during seed development in sunflower

4区 · 生物学

Article

作者: Thakur, Anita ; Bhatla, Satish C

Seed development in sunflower involves a gradual dehydration and accumulation of oil bodies in the cells of developing cotyledons during transition from 30 to 40 DAA stage. Reactive oxygen species (ROS) content decreased with seed maturation. NO content and NO contributed by putative nitric oxide synthase, however, did not change markedly. Superoxide dismutase (SOD) activity exhibited a peak at 30 DAA stage, indicating its scavenging role at the mid-stage of seed development. H₂O₂ produced as a result of SOD action is subsequently scavenged primarily by elevation of GR activity. Significant temporal differences were evident in GR and POD activity during seed development. Protein kinase C (PKC) activity also showed modulation during early stages of embryo and seed development. Use of PKC-specific fluorescent probe, Fim-1, and PKC inhibitors (staurosporine and bisindoylmaleamide) provided evidence for increase in PKC activity at 40 DAA stage with an increase in protein concentration (50 to 200 µg). Endogenous calcium content also increased with seed maturation. Tissue homogenates from 40 DAA stage showed enhanced fluorescence due to Fim-1-PKC binding in presence of calcium ions and its lowering due to calcium chelating agent (BAPTA). Western blot analysis revealed an increase in the intensity of 2 bands representing PKC with the advancement of seed maturation and their further upregulation by calcium. Present findings, thus, provide new information on the biochemical regulation of seed development in sunflower, with evidence for a possible correlation between calcium, ROS, their scavenging enzymes and "conventional" PKC activity.

2012-07-01·Journal of immunology (Baltimore, Md. : 1950)2区 · 医学

TLR Signaling Prevents Hyperoxia-Induced Lung Injury by Protecting the Alveolar Epithelium from Oxidant-Mediated Death

2区 · 医学

Article

作者: Flavell, Richard A. ; Zeng, Xianying ; Newstead, Michael W. ; Pinsky, David J. ; Bhan, Urvashi ; Moore, Bethany B. ; Standiford, Theodore J. ; Horowitz, Jeffrey C. ; Ballinger, Megan N.

Abstract:

Mechanical ventilation using high oxygen tensions is often necessary to treat patients with respiratory failure. Recently, TLRs were identified as regulators of noninfectious oxidative lung injury. IRAK-M is an inhibitor of MyD88-dependent TLR signaling. Exposure of mice deficient in IRAK-M (IRAK-M−/−) to 95% oxygen resulted in reduced mortality compared with wild-type mice and occurred in association with decreased alveolar permeability and cell death. Using a bone marrow chimera model, we determined that IRAK-M’s effects were mediated by structural cells rather than bone marrow-derived cells. We confirmed the expression of IRAK-M in alveolar epithelial cells (AECs) and showed that hyperoxia can induce the expression of this protein. In addition, IRAK-M−/− AECs exposed to hyperoxia experienced a decrease in cell death. IRAK-M may potentiate hyperoxic injury by suppression of key antioxidant pathways, because lungs and AECs isolated from IRAK-M−/− mice have increased expression/activity of heme oxygenase-1, a phase II antioxidant, and NF (erythroid-derived)-related factor-2, a transcription factor that initiates antioxidant generation. Treatment of IRAK-M−/− mice in vivo and IRAK-M−/− AECs in vitro with the heme oxygenase-1 inhibitor, tin protoporphyrin, substantially decreased survival and significantly reduced the number of live cells after hyperoxia exposure. Collectively, our data suggest that IRAK-M inhibits the induction of antioxidants essential for protecting the lungs against cell death, resulting in enhanced susceptibility to hyperoxic lung injury.

项与 FIM-001 相关的新闻（医药）

2024-07-07

·医药观澜

开发“first-in-class”药物的关键！6月哪些前沿靶点值得关注？

▎药明康德内容团队编辑药明康德内容团队盘点了2024年6月发布于国际知名科研期刊中的潜力靶点，供各位医药界的朋友们参考。它们有的是肿瘤中的生物力学检查点，有的是视网膜色素上皮中的关键免疫调节因子，有的在多囊卵巢综合征发生过程中具有重要作用。这些潜力靶点涵盖癌症、代谢类疾病、中枢神经系统疾病、传染病等多个方向，都具有潜在转化价值。在这篇文章中，我们优选5个值得关注的靶点做详细报道。点击“阅读原文”或扫描文中二维码并填写文中调查问卷，留下您的邮箱，即可申请获得完整靶点列表。 ▲点击“阅读原文”或扫描以上二维码并填写问卷，以申请获得《2024年6月潜在可转化创新靶点》分析报告靶点：LONP1 应用：治疗多囊卵巢综合征的靶点期刊/ PMID：《科学》 / 38870290 发现：多囊卵巢综合征（PCOS）是育龄妇女常见的内分泌疾病，表现包括雄激素过多和其他激素变化、月经周期改变、不孕和代谢异常。尽管发病率很高，但由于PCOS的复杂性，研发有效的药物极具挑战。这项研究发现青蒿素衍生物可以通过抑制卵巢雄激素合成来控制高雄激素血症，缓解啮齿动物模型和人类患者的PCOS症状。进一步的机制探索发现青蒿素促进P450家族成员CYP11A1蛋白的降解，从而阻止雄激素的过度生成。而青蒿素直接靶向LONP1，通过增强LONP1与CYP11A1的相互作用，促进LONP1催化的CYP11A1降解。过表达LONP1复制了青蒿素的降雄激素效果。这表明LONP1-CYP11A1相互作用在控制高雄激素血症和PCOS的发生中有关键作用。靶向LONP1-CYP11A1相互作用可能为PCOS治疗开辟新途径。 ▲青蒿素可抑制卵巢雄激素合成并缓解多囊卵巢综合征（图片来源：参考资料[1]）靶点：Osr2 应用：加剧T细胞耗竭的生物力学检查点期刊/ PMID：《细胞》/ 38744281 发现：细胞外基质（ECM）的结构和刚性改变是癌症的标志性特征之一。但ECM的生物力学特性是否影响抗肿瘤CD8+ T细胞的功能仍然未知。这项研究发现Osr2可以整合生物力学信号，促进肿瘤CD8+ T细胞的终末耗竭。通过T细胞受体信号和由Piezo1/钙/CREB轴介导的生物力学应力，Osr2在终末耗竭的肿瘤特异性CD8+ T细胞亚群中被选择性诱导。敲除Osr2可以减轻肿瘤特异性CD8+ T细胞或CAR-T细胞的耗竭，过表达Osr2则在实体瘤模型中加剧了它们的耗竭。机制上，Osr2招募HDAC3重塑表观遗传程序，以抑制细胞毒性基因的表达，促进CD8+ T细胞的耗竭。这揭示Osr2是生物力学检查点，功能上加剧CD8+ T细胞耗竭，有潜力成为增强癌症免疫治疗疗效的靶点。 ▲Osr2作为生物力学检查点，加剧肿瘤中的CD8+T细胞耗竭（图片来源：参考资料[2]）靶点：NAT8L 应用：增强抗癌药物疗效的潜在靶点期刊/ PMID：Cancer Cell / 38821061 发现：肿瘤细胞有多种逃避免疫监视的策略。中枢神经系统（CNS）也有限制免疫反应的特征。但尚不清楚肿瘤和CNS是否共享相似的免疫抑制程序。这项研究通过分析肿瘤多组学数据，发现CNS富集的N-乙酰基转移酶8样物质（NAT8L），而其代谢产物N-乙酰天冬氨酸（NAA）在耐药肿瘤中也有高表达。在CNS中，NAA在脑部发生炎症期间释放。NAT8L通过NAA抑制NK细胞和CD8+ T细胞的细胞毒性，这既能减轻脑部炎症，也可以削弱抗肿瘤免疫反应。在机制上，NAA通过促进PCAF诱导的核纤层蛋白A-K542的乙酰化，破坏免疫突触的形成，破坏胞溶性颗粒的极化。该研究成果意味着肿瘤细胞存在模仿CNS抗炎机制的免疫逃逸策略，而NAT8L是一个增强抗癌药物疗效的潜在靶点。 ▲NAT8L通过NAA抑制NK细胞和CD8+ T细胞的细胞毒性（图片来源：参考资料[3]）靶点：IRAK-M 应用：减轻视网膜变性的潜在靶点期刊/ PMID：Science Translational Medicine / 38838135 发现：年龄相关性黄斑变性（AMD）的进展与慢性炎症有关，但AMD中，TLR和IL-1R炎症信号通路中必要的Myddosome复合物的作用尚未阐明。这项研究发现抑制性Myddosome的成分IRAK-M是视网膜色素上皮（RPE）的关键免疫调节因子。研究人员发现编码IRAK-M的IRAK3基因中的罕见变异与晚期AMD风险增加有关。人体样本和小鼠模型中，RPE的IRAK-M随着年龄增长或氧化应激减少，在AMD中进一步降低。Irak3基因敲除小鼠在较早年龄就表现出更高的外视网膜变性发病率，氧化应激使这种情况进一步恶化。缺乏IRAK-M导致RPE细胞稳态被破坏，表现为线粒体功能受损、细胞衰老和异常的细胞因子生产。过表达IRAK-M能保护RPE细胞免受氧化或免疫应激的损害。通过AAV在野生型小鼠视网膜下递送人IRAK3基因挽救了光诱导的外视网膜变性，并减轻Irak3基因敲除小鼠的年龄相关自发性视网膜变性。这些数据表明，在RPE中补充IRAK-M可以纠正AMD中失调的炎症反应，是视网膜变性的潜在治疗方法。图片来源：123RF 靶点：OTUD5 应用：糖尿病肾病的潜在治疗靶点期刊/ PMID：Nature Communications / 38937512 发现：足细胞损伤在糖尿病肾病（DKD）发展中起着至关重要的作用。这项研究探索了一种去泛素化酶OTUD5在足细胞损伤和DKD中的作用及其调控机制。研究人员通过RNA-seq分析，发现在高糖高脂刺激的足细胞中，OTUD5表达显著降低。特异性敲除足细胞中的Otud5基因会加重1型和2型糖尿病小鼠的足细胞损伤和DKD。在足细胞中过表达OTUD5则对DKD显示出治疗效果。质谱和共免疫沉淀实验揭示在足细胞中，炎症调节蛋白TAK1是OTUD5的底物。OTUD5通过其活性位点C224对K63连接的TAK1的K158位点去泛素化，阻止TAK1磷酸化，进而减少下游炎症反应。该研究发现OTUD5-TAK1通路在足细胞炎症和损伤中起关键作用，揭示了OTUD5作为DKD治疗靶点的潜力。 ▲OTUD5足细胞特异性过表达可减轻2型糖尿病小鼠的足细胞损伤和DKD（图片来源：参考资料[5]）潜在靶点众多，限于篇幅，本文不一一进行介绍。请点击“阅读原文”或扫描文中二维码并填写文中调查问卷，留下您的邮箱，即可申请获得完整靶点列表。 ▲点击“阅读原文”或扫描以上二维码并填写问卷，以申请获得《2024年6月潜在可转化创新靶点》分析报告参考资料： [1] Liu, Yang et al. “Artemisinins ameliorate polycystic ovarian syndrome by mediating LONP1-CYP11A1 interaction.” Science (New York, N.Y.) vol. 384,6701 (2024): eadk5382. doi:10.1126/science.adk5382 [2] Zhang, Jinjia et al. “Osr2 functions as a biomechanical checkpoint to aggravate CD8+ T cell exhaustion in tumor.” Cell vol. 187,13 (2024): 3409-3426.e24. doi:10.1016/j.cell.2024.04.023 [3] Li, Yihong et al. “Tumor cells impair immunological synapse formation via central nervous system-enriched metabolite.” Cancer cell vol. 42,6 (2024): 985-1002.e18. doi:10.1016/j.ccell.2024.05.006 [4] Liu, Jian et al. “Replenishing IRAK-M expression in retinal pigment epithelium attenuates outer retinal degeneration.” Science translational medicine vol. 16,750 (2024): eadi4125. doi:10.1126/scitranslmed.adi4125 [5] Zhao, Ying et al. “Podocyte OTUD5 alleviates diabetic kidney disease through deubiquitinating TAK1 and reducing podocyte inflammation and injury.” Nature communications vol. 15,1 5441. 27 Jun. 2024, doi:10.1038/s41467-024-49854-1 本文来自药明康德内容团队，欢迎个人转发至朋友圈，谢绝媒体或机构未经授权以任何形式转载至其他平台。转载授权请在「药明康德」微信公众号留言联系我们。其他合作需求，请联系wuxi_media@wuxiapptec.com。免责声明：药明康德内容团队专注介绍全球生物医药健康研究进展。本文仅作信息交流之目的，文中观点不代表药明康德立场，亦不代表药明康德支持或反对文中观点。本文也不是治疗方案推荐。如需获得治疗方案指导，请前往正规医院就诊。

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