The Receptor for Advanced Glycation End Products (RAGE) Affects T Cell Differentiation in OVA Induced Asthma

The receptor for glycation end products (RAGE) has been previously implicated in shaping the adaptive immune response. RAGE is expressed in T cells after activation and constitutively in T cells from patients with diabetes. The effects of RAGE on adaptive immune responses are not clear: Previous reports show that RAGE blockade affects Th1 responses. To clarify the role of RAGE in adaptive immune responses and the mechanisms of its effects, we examined whether RAGE plays a role in T cell activation in a Th2 response involving ovalbumin (OVA)-induced asthma in mice. WT and RAGE deficient wild-type and OT-II mice, expressing a T cell receptor specific for OVA, were immunized intranasally with OVA. Lung cellular infiltration and T cell responses were analyzed by immunostaining, FACS, and multiplex bead analyses for cytokines. RAGE deficient mice showed reduced cellular infiltration in the bronchial alveolar lavage fluid and impaired T cell activation in the mediastinal lymph nodes when compared with WT mice. In addition, RAGE deficiency resulted in reduced OT-II T cell infiltration of the lung and impaired IFNγ and IL-5 production when compared with WT mice and reduced infiltration when transferred into WT hosts. When cultured under conditions favoring the differentiation of T cells subsets, RAGE deficient T cells showed reduced production of IFNγ but increased production of IL-17. Our data show a stimulatory role for RAGE in T activation in OVA-induced asthma. This role is largely mediated by the effects of RAGE on T cell proliferation and differentiation. These findings suggest that RAGE may play a regulatory role in T cell responses following immune activation.     

Protein Tyrosine Phosphatase Receptor Type Z Negatively Regulates Oligodendrocyte Differentiation and Myelination

Background

Fyn tyrosine kinase-mediated down-regulation of Rho activity through activation of p190RhoGAP is crucial for oligodendrocyte differentiation and myelination. Therefore, the loss of function of its counterpart protein tyrosine phosphatase (PTP) may enhance myelination during development and remyelination in demyelinating diseases. To test this hypothesis, we investigated whether Ptprz, a receptor-like PTP (RPTP) expressed abuntantly in oligodendrocyte lineage cells, is involved in this process, because we recently revealed that p190RhoGAP is a physiological substrate for Ptprz.

Methodology/Principal Findings

We found an early onset of the expression of myelin basic protein (MBP), a major protein of the myelin sheath, and early initiation of myelination in vivo during development of the Ptprz-deficient mouse, as compared with the wild-type. In addition, oligodendrocytes appeared earlier in primary cultures from Ptprz-deficient mice than wild-type mice. Furthermore, adult Ptprz-deficient mice were less susceptible to experimental autoimmune encephalomyelitis (EAE) induced by active immunization with myelin/oligodendrocyte glycoprotein (MOG) peptide than were wild-type mice. After EAE was induced, the tyrosine phosphorylation of p190RhoGAP increased significantly, and the EAE-induced loss of MBP was markedly suppressed in the white matter of the spinal cord in Ptprz-deficient mice. Here, the number of T-cells and macrophages/microglia infiltrating into the spinal cord did not differ between the two genotypes after MOG immunization. All these findings strongly support the validity of our hypothesis.

Conclusions/Significance

Ptprz plays a negative role in oligodendrocyte differentiation in early central nervous system (CNS) development and remyelination in demyelinating CNS diseases, through the dephosphorylation of substrates such as p190RhoGAP.     

The Receptor for Advanced Glycation End Products (RAGE) Contributes to the Progression of Emphysema in Mice

Several recent clinical studies have implied a role for the receptor for advanced glycation end products (RAGE) and its variants in chronic obstructive pulmonary disease (COPD). In this study we have defined a role for RAGE in the pathogenesis of emphysema in mice. RAGE deficient mice (RAGE-/-) exposed to chronic cigarette smoke were significantly protected from smoke induced emphysema as determined by airspace enlargement and had no significant reduction in lung tissue elastance when compared to their air exposed controls contrary to their wild type littermates. The progression of emphysema has been largely attributed to an increased inflammatory cell-mediated elastolysis. Acute cigarette smoke exposure in RAGE-/- mice revealed an impaired early recruitment of neutrophils, approximately a 6-fold decrease compared to wild type mice. Hence, impaired neutrophil recruitment with continued cigarette smoke exposure reduces elastolysis and consequent emphysema.     

Overexpression of the Receptor for Advanced Glycation Endproducts (RAGE) Is Associated with Poor Prognosis in Gastric Cancer

Background

The receptor for advanced glycation endproducts (RAGE) is an oncogenic multidisciplinary trans-membranous receptor, which is overexpressed in multiple human cancers. Recently, it has been shown that RAGE is also involved in carcinogenesis and tumor invasion. In this study, we investigated the expression levels and prognostic value of RAGE in primary gastric cancers (GC).

Methods

We investigated RAGE expression in primary GC and paired normal gastric tissue by real-time quantitative RT-PCR (n = 30) and Western blotting analysis (n = 30). Additionally, we performed immunohistochemistry on 180 paraffin-embedded GC specimens, 69 matched normal specimens.

Results

RAGE was overexpressed in GC compared with the adjacent noncancerous tissues (P＜0.001), and higher RAGE expression significantly correlated with the histological grade (P = 0.002), nodal status(P = 0.025), metastasis status(P = 0.002), and American Joint Committee on Cancer stage (P = 0.020). Furthermore, upregulation of RAGE expression is an independent prognostic factor in multivariate analysis using the Cox regression model (P = 0.001).

Conclusions

RAGE Overexpression may be a useful marker to predict GC progression and poor prognosis.     

Receptor for Advanced Glycation End Products (RAGE) Serves a Protective Role during Klebsiella pneumoniae - Induced Pneumonia

Klebsiella species is the second most commonly isolated gram-negative organism in sepsis and a frequent causative pathogen in pneumonia. The receptor for advanced glycation end products (RAGE) is expressed on different cell types and plays a key role in diverse inflammatory responses. We here aimed to investigate the role of RAGE in the host response to Klebsiella (K.) pneumoniae pneumonia and intransally inoculated rage gene deficient (RAGE^-/-) and normal wild-type (Wt) mice with K. pneumoniae. Klebsiella pneumonia resulted in an increased pulmonary expression of RAGE. Furthermore, the high-affinity RAGE ligand high mobility group box-1 was upregulated during K. pneumoniae pneumonia. RAGE deficiency impaired host defense as reflected by a worsened survival, increased bacterial outgrowth and dissemination in RAGE^-/- mice. RAGE^-/- neutrophils showed a diminished phagocytosing capacity of live K. pneumoniae in vitro. Relative to Wt mice, RAGE^-/- mice demonstrated similar lung inflammation, and slightly elevated—if any—cytokine and chemokine levels and unchanged hepatocellular injury. In addition, RAGE^-/- mice displayed an unaltered response to intranasally instilled Klebsiella lipopolysaccharide (LPS) with respect to pulmonary cell recruitment and local release of cytokines and chemokines. These data suggest that (endogenous) RAGE protects against K. pneumoniae pneumonia. Also, they demonstrate that RAGE contributes to an effective antibacterial defense during K. pneumoniae pneumonia, at least partly via its participation in the phagocytic properties of professional granulocytes. Additionally, our results indicate that RAGE is not essential for the induction of a local and systemic inflammatory response to either intact Klebsiella or Klebsiella LPS.     

Hydrogen Peroxide Stimulates Exosomal Cathepsin B Regulation of the Receptor for Advanced Glycation End‐Products (RAGE)

Exosomes are nano‐sized vesicles that are secreted into the extracellular environment. These vesicles contain various biological effector molecules that can regulate intracellular signaling pathways in recipient cells. The aim of this study was to examine a correlation between exosomal cathepsin B activity and the receptor for advanced glycation end‐products (RAGE). Type 1 alveolar epithelial (R3/1) cells were treated with or without hydrogen peroxide and exosomes isolated from the cell conditioned media were characterized by NanoSight analysis. Lipidomic and proteomic analysis showed exosomes released from R3/1 cells exposed to oxidative stress induced by hydrogen peroxide or vehicle differ in their lipid and protein content, respectively. Cathepsin B activity was detected in exosomes isolated from hydrogen peroxide treated cells. The mRNA and protein expression of RAGE increased in cultured R3/1 cells treated with exosomes containing active cathepsin B while depletion of exosomal cathepsin B attenuated RAGE mRNA and protein expression. These results suggest exosomal cathepsin B regulates RAGE in type 1 alveolar cells under conditions of oxidative stress. J. Cell. Biochem. 119: 599–606, 2018. © 2017 Wiley Periodicals, Inc.     

ADAM10 Negatively Regulates Neuronal Differentiation during Spinal Cord Development

Members of the ADAM (a disintegrin and metalloprotease) family are involved in embryogenesis and tissue formation via their proteolytic function, cell-cell and cell-matrix interactions. ADAM10 is expressed temporally and spatially in the developing chicken spinal cord, but its function remains elusive. In the present study, we address this question by electroporating ADAM10 specific morpholino antisense oligonucleotides (ADAM10-mo) or dominant-negative ADAM10 (dn-ADAM10) plasmid into the developing chicken spinal cord as well as by in vitro cell culture investigation. Our results show that downregulation of ADAM10 drives precocious differentiation of neural progenitor cells and radial glial cells, resulting in an increase of neurons in the developing spinal cord, even in the prospective ventricular zone. Remarkably, overexpression of the dn-ADAM10 plasmid mutated in the metalloprotease domain (dn-ADAM10-me) mimics the phenotype as found by the ADAM10-mo transfection. Furthermore, in vitro experiments on cultured cells demonstrate that downregulation of ADAM10 decreases the amount of the cleaved intracellular part of Notch1 receptor and its target, and increases the number of βIII-tubulin-positive cells during neural progenitor cell differentiation. Taken together, our data suggest that ADAM10 negatively regulates neuronal differentiation, possibly via its proteolytic effect on the Notch signaling during development of the spinal cord.     

Tetratricopeptide Repeat Domain 9A Negatively Regulates Estrogen Receptor Alpha Activity

Tetratricopeptide repeat domain 9A (TTC9A) is a target gene of estrogen and progesterone. It is over-expressed in breast cancer. However, little is known about the physiological function of TTC9A. The objectives of this study were to establish a Ttc9a knockout mouse model and to study the consequence of Ttc9a gene inactivation. The Ttc9a targeting vector was generated by replacing the Ttc9a exon 1 with a neomycin cassette. The mice homozygous for Ttc9a exon 1 deletion appear to grow normally and are fertile. However, further characterization of the female mice revealed that Ttc9a deficiency is associated with greater body weight, bigger thymus and better mammary development in post-pubertal mice. Furthermore, Ttc9a deficient mammary gland was more responsive to estrogen treatment with greater mammary ductal lengthening, ductal branching and estrogen target gene induction. Since Ttc9a is induced by estrogen in estrogen target tissues, these results suggest that Ttc9a is a negative regulator of estrogen function through a negative feedback mechanism. This is supported by in vitro evidence that TTC9A over-expression attenuated ERα activity in MCF-7 cells. Although TTC9A does not bind to ERα or its chaperone protein Hsp90 directly, TTC9A strongly interacts with FKBP38 and FKBP51, both of which interact with ERα and Hsp90 and modulate ERα activity. It is plausible therefore that TTC9A negatively regulates ERα activity through interacting with co-chaperone proteins such as FKBP38 and FKBP51.     

Biologically Active Fragment of the Receptor for Advanced Glycation End Products (RAGE) Is Able to Inhibit Oligomerization of the Beta-Amyloid

Russian Journal of Bioorganic Chemistry - It was found earlier that the synthetic fragment corresponding to the 60–76 sequence of the extracellular domain of the receptor for advanced...     

Nucleoredoxin Negatively Regulates Toll-like Receptor 4 Signaling via Recruitment of Flightless-I to Myeloid Differentiation Primary Response Gene (88)

We previously characterized nucleoredoxin (NRX) as a negative regulator of the Wnt signaling pathway through Dishevelled (Dvl). We perform a comprehensive search for other NRX-interacting proteins and identify Flightless-I (Fli-I) as a novel NRX-binding partner. Fli-I binds to NRX and other related proteins, such as Rod-derived cone viability factor (RdCVF), whereas Dvl binds only to NRX. Endogenous NRX and Fli-I in vivo interactions are confirmed. Both NRX and RdCVF link Fli-I with myeloid differentiation primary response gene (88) (MyD88), an important adaptor protein for innate immune response. NRX and RdCVF also potentiate the negative effect of Fli-I upon lipopolysaccharide-induced activation of NF-κB through the Toll-like receptor 4/MyD88 pathway. Embryonic fibroblasts derived from NRX gene-targeted mice show aberrant NF-κB activation upon lipopolysaccharide stimulation. These results suggest that the NRX subfamily of proteins forms a link between MyD88 and Fli-I to mediate negative regulation of the Toll-like receptor 4/MyD88 pathway.     

Soluble Receptor for Advanced Glycation End-products regulates age-associated Cardiac Fibrosis

Myocardial aging increases the cardiovascular risk in the elderly. The Receptor for Advanced Glycation End-products (RAGE) is involved in age-related disorders. The soluble isoform (sRAGE) acts as a scavenger blocking the membrane-bound receptor activation. This study aims at investigating RAGE contribution to age-related cardiac remodeling.We analyzed the cardiac function of three different age groups of female Rage-/- and C57BL/6N (WT) mice: 2.5- (Young), 12- (Middle-age, MA) and 21-months (Old) old. While aging, Rage-/- mice displayed an increase in left ventricle (LV) dimensions compared to age-matched WT animals, with the main differences observed in the MA groups. Rage-/- mice showed higher fibrosis and a larger number of α-Smooth Muscle Actin (SMA)+ cells with age, along with increased expression of pro-fibrotic Transforming Growth Factor (TGF)-β1 pathway components. RAGE isoforms were undetectable in LV of WT mice, nevertheless, circulating sRAGE declined with aging and inversely associated with LV diastolic dimensions. Human cardiac fibroblasts stimulated with sRAGE exhibited a reduction in proliferation, pro-fibrotic proteins and TGF-beta Receptor 1 (TGFbR1) expression and Smad2-3 activation. Finally, sRAGE administration to MA WT animals reduced cardiac fibrosis.Hence, our work shows that RAGE associates with age-dependent myocardial changes and indicates sRAGE as an inhibitor of cardiac fibroblasts differentiation and age-dependent cardiac fibrosis.     

Modeling the Interaction between Quinolinate and the Receptor for Advanced Glycation End Products (RAGE): Relevance for Early Neuropathological Processes

The receptor for advanced glycation end products (RAGE) is a pattern-recognition receptor involved in neurodegenerative and inflammatory disorders. RAGE induces cellular signaling upon binding to a variety of ligands. Evidence suggests that RAGE up-regulation is involved in quinolinate (QUIN)-induced toxicity. We investigated the QUIN-induced toxic events associated with early noxious responses, which might be linked to signaling cascades leading to cell death. The extent of early cellular damage caused by this receptor in the rat striatum was characterized by image processing methods. To document the direct interaction between QUIN and RAGE, we determined the binding constant (K_b) of RAGE (VC1 domain) with QUIN through a fluorescence assay. We modeled possible binding sites of QUIN to the VC1 domain for both rat and human RAGE. QUIN was found to bind at multiple sites to the VC1 dimer, each leading to particular mechanistic scenarios for the signaling evoked by QUIN binding, some of which directly alter RAGE oligomerization. This work contributes to the understanding of the phenomenon of RAGE-QUIN recognition, leading to the modulation of RAGE function.     

Receptor for Advanced Glycation Endproducts (RAGE): a formidable force in the pathogenesis of the cardiovascular complications of diabetes & aging

Unifying mechanisms for the consequences of aging and chronic diabetes are coming to light with the identification that common to both settings is the production and accumulation of the largely irreversible Advanced Glycation Endproducts (AGEs). AGEs impart multiple consequences in the tissues; a key means by which they exert maladaptive effects is via their interaction with and activation of their chief cell surface receptor, Receptor for AGE or RAGE. Although the time course, rate and extent of AGE generation and accumulation in diabetes and aging may be distinct, unifying outcomes of the ligand-RAGE interaction in the vasculature and heart are linked to upregulation of inflammatory and tissue-destructive mechanisms. Consistent with these concepts, administration of the ligand-binding decoy of RAGE, soluble or sRAGE, suppresses early initiation and progression of atherosclerosis in diabetic mice; suppresses exaggerated neointimal expansion consequent to arterial injury; and mitigates the adverse impact of ischemia/reperfusion injury in the heart. Importantly, the RAGE ligand repertoire upregulated in these settings is not limited to AGEs. The key finding that RAGE was a multi-ligand receptor unified the concept that in diabetes and aging, innate and adaptive inflammatory mechanisms contribute to the pathogenesis of tissue injury. We conclude that antagonism of RAGE may reflect a novel and therapeutically logical and safe target in cardiovascular stress induced by aging and chronic diabetes.     

Effect of Transient Cerebral Ischemia on the Expression of Receptor for Advanced Glycation End Products (RAGE) in the Gerbil Hippocampus Proper

The receptor for advanced glycation end products (RAGE) is a multi-ligand receptor of the immunoglobulin superfamily that has been implicated in multiple neuronal and inflammatory stress processes. In this study, we examined changes in RAGE immunoreactivity and its protein levels in the gerbil hippocampus (CA1-3 regions) after 5 min of transient global cerebral ischemia. The ischemic hippocampus was stained with cresyl violet, neuronal nuclei (a neuron-specific soluble nuclear antigen) antibody and Fluoro-Jade B (a marker for neuronal degeneration). 5 days after ischemia–reperfusion, delayed neuronal death occurred in the stratum pyramidale of the CA1 region. RAGE immunoreactivity was not detected in any regions of the CA1-3 regions of the sham-group; the immunoreactivity was markedly increased only in the CA1 region from 3 days after ischemia–reperfusion. On the other hand, RAGE immunoreactivity was newly expressed in astrocytes, not in microglia. Western blot analysis showed that RAGE protein level was highest at 5 days post-ischemia. In brief, both the RAGE immunoreactivity and protein level were distinctively increased in astrocytes in the ischemic CA1 region from 3 days after transient cerebral ischemia. These results indicate that the increase of RAGE expression in astrocytes after ischemia–reperfusion may be related to the ischemia-caused activation of astrocytes in the ischemic CA1 region.     

RAGE 与阿尔茨海默病关系的研究进展

阿尔茨海默病属于神经系统退行性疾病,该类疾病给社会和家庭带来了沉重的负担,且目前尚无一疗效突破性药物,已经 成为一个严重的社会问题和经济问题。A茁是阿尔茨海默病的重要发病机制之一,通过多种途径介导神经损伤,其中与细胞表面 的结合位点结合而引发的病理损害成为当今的前沿认识。一方面,它们可以使A茁聚集,造成细胞膜的直接损伤;另一方面,它们 可以以受体的形式,参与细胞内的信号传导;另外,还可以激活细胞内吞作用,通过溶酶体途径造成细胞损伤。关于与A茁结合的 细胞表面结合位点,晚期糖基化终末产物受体备受瞩目。它是一种多功能受体,属于细胞表面免疫球蛋白家族成员, 在神经元、小 胶质细胞以及血管内皮细胞上都有表达,A茁是它的配体之一。研究已证实,它与A茁相互作用,通过激活细胞内不同的信号通路, 对阿尔茨海默病的发生发展发挥重要作用。随着对它的不断深入研究,有望在防治退行性疾病方面产生新的治疗策略与措施。     

晚期糖基化终产物通过其受体促进内皮细胞分泌IL-8的研究

探讨晚期糖基化终产物(AGE)修饰蛋白对内皮细胞生成白介素8(IL-8)的作用,及晚期糖基化终产物受体(RAGE)在此病理过程中的作用.内皮细胞来自培养的人脐静脉内皮细胞(HUVEC).将内皮细胞与不同浓度的AGE修饰人血清白蛋白(AGE-HSA)在体外共同培养,或以可溶性晚期糖基化终产物受体(sRAGE)对AGE-HSA进行预处理后再与HUVEC共同培养.用蛋白质液相芯片法检测HUVEC培养上清中IL-8水平,并提取细胞RNA,进行RT-PCR反应,检测细胞中IL-8 mRNA的表达水平.结果表明,AGE-HSA以时间和剂量依赖的方式刺激HUVEC生成IL-8,未经修饰的HSA无此作用.AGE-HSA用sRAGE预处理后,刺激HUVEC生成IL-8的作用被抑制,并且此抑制作用呈剂量依赖的方式.AGE-HSA刺激HUVEC使IL-8 mRNA表达增高,未经修饰的HSA无此作用.sRAGE能够阻断AGE-HSA诱导HUVEC表达IL-8mRNA的作用.整个变化趋势与蛋白质水平一致.研究首次证实,AGE-HSA与细胞表面受体RAGE相互作用可刺激内皮细胞分泌IL-8,并上调IL-8 mRNA的表达.这为研究加速型血管病变的发病机制提供了新视角,也为治疗由AGE增多和潴留所引起的病理损害提供了新靶点.     

The Receptor for Advanced Glycation End-Products (RAGE) Is Only Present in Mammals,and Belongs to a Family of Cell Adhesion Molecules (CAMs)

The human receptor for advanced glycation endproducts (RAGE) is a multiligand cell surface protein belonging to the immunoglobulin superfamily, and is involved in inflammatory and immune responses. Most importantly, RAGE is considered a receptor for HMGB1 and several S100 proteins, which are Damage-Associated Molecular Pattern molecules (DAMPs) released during tissue damage. In this study we show that the Ager gene coding for RAGE first appeared in mammals, and is closely related to other genes coding for cell adhesion molecules (CAMs) such as ALCAM, BCAM and MCAM that appeared earlier during metazoan evolution. RAGE is expressed at very low levels in most cells, but when expressed at high levels, it mediates cell adhesion to extracellular matrix components and to other cells through homophilic interactions. Our results suggest that RAGE evolved from a family of CAMs, and might still act as an adhesion molecule, in particular in the lung where it is highly expressed or under pathological conditions characterized by an increase of its protein levels.